Refine
Year of publication
- 2014 (1214) (remove)
Document Type
- Article (588)
- Part of Periodical (163)
- Working Paper (149)
- Book (134)
- Doctoral Thesis (86)
- Report (27)
- Part of a Book (23)
- Conference Proceeding (18)
- Review (10)
- Preprint (8)
Language
- English (1214) (remove)
Keywords
- taxonomy (21)
- new species (19)
- Syntax (11)
- Inversionsfigur (10)
- Multistability (10)
- Multistable figures (10)
- Wahrnehmungswechsel (10)
- morphology (8)
- Bantusprachen (7)
- Benjamin, Walter (7)
Institute
- Medizin (231)
- Wirtschaftswissenschaften (149)
- Center for Financial Studies (CFS) (131)
- Physik (101)
- Biowissenschaften (88)
- Sustainable Architecture for Finance in Europe (SAFE) (86)
- House of Finance (HoF) (82)
- Biochemie und Chemie (48)
- Geowissenschaften (41)
- Gesellschaftswissenschaften (33)
The U-turn is a classical three-dimensional RNA folding motif first identified in the anticodon and T-loops of tRNAs. It also occurs frequently as a building block in other functional RNA structures in many different sequence and structural contexts. U-turns induce sharp changes in the direction of the RNA backbone and often conform to the 3-nt consensus sequence 5'-UNR-3' (N = any nucleotide, R = purine). The canonical U-turn motif is stabilized by a hydrogen bond between the N3 imino group of the U residue and the 3' phosphate group of the R residue as well as a hydrogen bond between the 2'-hydroxyl group of the uridine and the N7 nitrogen of the R residue. Here, we demonstrate that a protonated cytidine can functionally and structurally replace the uridine at the first position of the canonical U-turn motif in the apical loop of the neomycin riboswitch. Using NMR spectroscopy, we directly show that the N3 imino group of the protonated cytidine forms a hydrogen bond with the backbone phosphate 3' from the third nucleotide of the U-turn analogously to the imino group of the uridine in the canonical motif. In addition, we compare the stability of the hydrogen bonds in the mutant U-turn motif to the wild type and describe the NMR signature of the C+-phosphate interaction. Our results have implications for the prediction of RNA structural motifs and suggest simple approaches for the experimental identification of hydrogen bonds between protonated C-imino groups and the phosphate backbone.
A consistent muscle activation strategy underlies crawling and swimming in Caenorhabditis elegans
(2014)
Although undulatory swimming is observed in many organisms, the neuromuscular basis for undulatory movement patterns is not well understood. To better understand the basis for the generation of these movement patterns, we studied muscle activity in the nematode Caenorhabditis elegans. Caenorhabditis elegans exhibits a range of locomotion patterns: in low viscosity fluids the undulation has a wavelength longer than the body and propagates rapidly, while in high viscosity fluids or on agar media the undulatory waves are shorter and slower. Theoretical treatment of observed behaviour has suggested a large change in force–posture relationships at different viscosities, but analysis of bend propagation suggests that short-range proprioceptive feedback is used to control and generate body bends. How muscles could be activated in a way consistent with both these results is unclear. We therefore combined automated worm tracking with calcium imaging to determine muscle activation strategy in a variety of external substrates. Remarkably, we observed that across locomotion patterns spanning a threefold change in wavelength, peak muscle activation occurs approximately 45° (1/8th of a cycle) ahead of peak midline curvature. Although the location of peak force is predicted to vary widely, the activation pattern is consistent with required force in a model incorporating putative length- and velocity-dependence of muscle strength. Furthermore, a linear combination of local curvature and velocity can match the pattern of activation. This suggests that proprioception can enable the worm to swim effectively while working within the limitations of muscle biomechanics and neural control.
D2.1. provides further elaboration of the original research design and informs about ideas for the final Volume II of bEUcitizen. It is closely connected to task 1 of work package 2: specifying various concrete tasks for the different work packages and formulating overarching questions suitable to provide substantive cohesion and integration of the overall project. The elaboration of 10 crosscutting topics (to become chapters in the “horizontal” book, D2.3.) is a first step towards this goal. Discussing these cross-cutting topics is supposed to feed, infuse and inspire the work done in the different work packages and to build cross-cutting connections between them. Themes 1-10 merge into a valuable overview of the multi-faceted research on (EU) citizenship. They access the main issues of EU-citizenship and citizenship in general from different angles and different disciplines. Taken together these contributions help to identify barriers towards EU citizenship and ways to overcome them. Each Theme formulates questions how it might feed and be fed by further information and findings in the other work packages.
D2.1. is mainly meant for internal use. Its functions are firstly to inform about preliminary ideas, eventual contributions to planned final results and secondly to make out some more of less specific guiding questions that connect the work done by the single researchers in every different work package to the project as a whole. This task implies a normative yardstick, a clear picture of what would be a "good" EU citizenship practice. Elaborating on such a normative yardstick is a meta-topic that cuts across the range of cross-cutting topics presented in this working paper.
This article focuses on the opportunities and challenges of implementing an extensive reading project in an English as a foreign language classroom in Germany. Studies such as PISA have shown that comparatively poor German and foreign language reading skills are still a prevalent issue in German society today. Consequently, the question of how these poor results can be improved is of utmost importance. Reading motivation is often described as the ‘driving force of reading’. Research has shown that if reading motivation and reading for pleasure are supported, interest in reading in a foreign language can be created, which may in turn have a positive impact on the other influential factors in reading and related skills. Dörnyei’s framework of L2 motivation sums up the current thinking on reading motivation. With its constituents ‘language’, ‘learner’, and ‘learning situation’, it shows the aspects to be taken into consideration when it comes to the improvement of motivation. Within this theoretical framework, an ER project was conducted at a grammar school (Gymnasium) in Frankfurt/Main, Germany. On the basis of the gathered data, gained from questionnaires, worksheets and the transcript of a focus group discussion, six main categories could be identified. They point to the development of a positive attitude towards reading among the students and the potential of graphic novels as a motivating factor. It was also confirmed that a successful application of reading strategies led to increased motivation. Generally, the project showed that reading is still an issue amongst many teenagers and that an ER project can affect learners, their motivation and related language skills in a positive way.
Aim: The cytokine receptor tumor necrosis factor receptor superfamily member 9 (TNFRSF9) is mainly considered to be a co-stimulatory activation marker in hematopoietic cells. Several preclinical models have shown a dramatic beneficial effect of treatment approaches targeting TNFRSF9 with agonistic antibodies. However, preliminary clinical phase I/II studies were stopped after the occurrence of several severe deleterious side effects. In a previous study, it was demonstrated that TNFRSF9 was strongly expressed by reactive astrocytes in primary central nervous system (CNS) tumors, but was largely absent from tumor or inflammatory cells. The aim of the present study was to address the cellular source of TNFRSF9 expression in the setting of human melanoma brain metastasis, a highly immunogenic tumor with a prominent tropism to the CNS.
Methods: Melanoma brain metastasis was analyzed in a cohort of 78 patients by immunohistochemistry for TNFRSF9 and its expression was correlated with clinicopathological parameters including sex, age, survival, tumor size, number of tumor spots, and BRAF V600E expression status.
Results: Tumor necrosis factor receptor superfamily member 9 was frequently expressed independently on both melanoma and endothelial cells. In addition, TNFRSF9 was also present on smooth muscle cells of larger vessels and on a subset of lymphomonocytic tumor infiltrates. No association between TNFRSF9 expression and patient survival or other clinicopathological parameters was seen. Of note, several cases showed a gradual increase in TNFRSF9 expression on tumor cells with increasing distance from blood vessels, an observation that might be linked to hypoxia-driven TNFRSF9 expression in tumor cells.
Conclusion: The findings indicate that the cellular source of TNFRSF9 in melanoma brain metastasis largely exceeds the lymphomonocytic pool, and therefore further careful (re-) assessment of potential TNFRSF9 functions in cell types other than hematopoietic cells is needed. Furthermore, the hypothesis of hypoxia-driven TNFRSF9 expression in brain metastasis melanoma cells requires further functional testing.
Speolepta leptogaster (Winnertz, 1863) is frequently occurring in European subterranean environments. As for most cave animals, studies addressing non-anatomical aspects are sparse. Here we present the first molecular study on S. leptogaster. We investigated the demographic structure (i.e. COI locus) of 69 specimens from 36 underground populations in Hesse (Central German Uplands) to get first insights into the species’ dispersal ability.
In total, 14 haplotypes were revealed. Haplotype diversity was relatively high, whereas nucleotide diversity was low. Furthermore, a significant but low pattern of isolation-by-distance and (a) past population expansion event(s) were detected.
Our genetic results suggest a (good) active dispersal ability for Speolepta leptogaster. The occurrence of several surface records of adult specimens corroborates this hypothesis. We discuss the developmental stages of S. leptogaster in the context of the ecological classification system and regard the species as a eutroglophile. Evidence has been found to distinguish two larval types. A reconstructed life-cycle of the species is provided.
Does the rotten child spoil his companion? : spatial peer effects among children in rural India
(2014)
This paper identifies the effect of neighborhood peer groups on childhood skill acquisition using observational data. We incorporate spatial peer interaction, defined as a child's nearest geographical neighbors, into a production function of child cognitive development in Andhra Pradesh, India. Our peer group definition takes the form of networks, whose structure allows us to identify endogenous peer effects and contextual effects separately. We exploit variation over time to avoid confounding correlated with social effects. Our results suggest that spatial peer and neighborhood effects are strongly positively associated with a child's cognitive skill formation. Further, we explore the effect of peer groups in helping to provide insurance against the negative impact of idiosyncratic shocks to child learning. We find that the data reject full risk-sharing, but cannot rule out the existence of partial risk-sharing on behalf of peers. We show that peer effects are robust to different specifications of peer interactions and investigate the sensitivity of our estimates to potential misspecification of the network structure using Monte Carlo experiments.
Research in the field of Digital Humanities, also known as Humanities Computing, has seen a steady increase over the past years. Situated at the intersection of computing science and the humanities, present efforts focus on making resources such as texts, images, musical pieces and other semiotic artifacts digitally available, searchable and analysable. To this end, computational tools enabling textual search, visual analytics, data mining, statistics and natural language processing are harnessed to support the humanities researcher. The processing of large data sets with appropriate software opens up novel and fruitful approaches to questions in the traditional humanities. This report summarizes the Dagstuhl seminar 14301 on “Computational Humanities - bridging the gap between Computer Science and Digital Humanities”.
1998 ACM Subject Classification I.2.7 Natural Language Processing, J.5 Arts and Humanities
Ultrafast protein dynamics are of great interest for understanding the molecular basis of biochemical function. One method to study structural changes with highest time-resolution starting in the femtosecond regime is 2D-IR spectroscopy. However its application to investigate protein dynamics both with high temporal and spatial resolution is currently limited to few biological systems with intrinsic chromophores. Spectral congestion, the contribution of many similar oscillators to the same signals, makes it difficult to draw conclusions about local structural dynamics in most other proteins.
The aim of this thesis is to extend the application of 2D-IR spectroscopy to a wider range of proteins by introducing unnatural amino acids (UAAs) with azide or nitrile groups as site-specific vibrational probes, which absorb in the free spectral window between 1800 to 3000 cm-1 by using methods from chemical biology.
In a comparative experimental study using FTIR and 2D-IR spectroscopy of single amino acids azidohomoalanine (Aha), a methionine analogue, was identified as preferred label. To demonstrate the application potential of UAAs as site-specific probes, Aha was then incorporated into different positions in a small globular protein. By using both FTIR and ultrafast 2D-IR it was shown, that indeed the local microenvironment as well as conformational fluctuations on picosecond timescale could be monitored with high spatial information. The azide moiety shows a shift of its absorption frequency depending on the polarity of its surrounding. Using this approach, different subensembles for the protein conformations with more polar and less polar environment around the vibrational probe can be distinguished.
A second major application of site-specific labels is the study of vibrational energy transfer processes (VET), predicted to be relevant for allosteric communication in protein domains such as the PDZ domain. VET can be tracked with high spatial resolution using time-resolved IR spectroscopy by exciting a localized vibrational mode and probing separate modes in a two-colour 2D-IR experiment. To extend this kind of experiment to proteins, a specific donor-acceptor pair of two UAAs was introduced. It uses an azulene moiety as donor that can be excited in the visible range but deposits the excess energy by internal conversion into the vibrational modes of the ground state. In small peptides this VET pair was applied successfully, showing a distance-dependent energy transfer induced signal for VET through covalent bonds. These findings bare great promise for the direct observation of vibrational energy flow in proteins in real-time.
Overall this thesis is the basis for extending the usability of 2D-IR spectroscopy to study structural dynamics in a wide range of proteins systems both with high temporal and spatial resolution.
Benjamin's early reception in the United States can be broken into eight phases: 1) a few notices of his work in the 1930s; 2) the appearance of two major works, without translation, in the 'Zeitschrift für Sozialforschung', when it was published in New York and mimeographed in Los Angeles; 3) several reports of his suicide along with the death of other Jewish and left-wing writers who fell victim to Nazi terror; 4) scattered use of his work in the late 1940s and 1950s; 5) a growing realization in the early 1960s that American literary and cultural criticism was missing something of significance by neglecting Benjamin's work; 6) the appearance in the 1960s of competing portraits of Benjamin by four of his surviving friends, including Hannah Arendt, who edited and introduced the first collection of his writings in English; 7) an uncanny repetition of the earlier neglect, as a significant number of Benjamin's texts are published in Great Britain during the 1970s and early 1980s but remain unavailable in the States; 8) the beginning of a sustained critical engagement with Benjamin in the late 1970s.
At the forefront of those who tenaciously pondered this issue are, I would claim, Walter Benjamin and Ludwig Wittgenstein. Benjamin and Wittgenstein both are philosophers of language who tried to establish in unique ways the doctrine of resemblance respectively: "Lehre vom Ähnlichen" and "[Lehre der] Familienähnlichkeit." What they see and find in language are not communication and mutual understanding but instead one of the weirdest phenomena in/of the world, viz., resemblance (likeness) in/of language. This phenomenon, I would insist, indicates the correlation of appearing and disappearing, of differentiating and integrating, and of dividing and imparting of language as such. For Benjamin and Wittgenstein, to sum up, language is a paradigmatic paradoxical site of (dis)appearance, differentiating integrity, and divisive imparting. For this reason, it is worthwhile to pin down where their thoughts on language converge and where they diverge.
To explicate what distinguishes pain, Benjamin elaborates: "Of all corporeal feelings, pain alone is like a navigable river which never dries up and which leads man down to the sea. [...] Pain [...] is a link between worlds. This is why organic pleasure is intermittent, whereas pain can be permanent. This comparison of pleasure and pain explains why the cause of pain is irrelevant for the understanding of man's nature, whereas the source of his greatest pleasure is extremely important. For every pain, even the most trivial one, can lead upward to the highest religious suffering, whereas pleasure is not capable of any enhancement, and owes any nobility it possesses to the grace of its birth - that is to say, its source. (SW I, 397)" In these important lines, pain's unique strength is linked not to its origin (this is reserved for pleasure), but rather to the way that its strenuous flow throughout the suffering body has the power to lead it to infinite heights. In contrast to pleasure, which is forever seeking out its sources, pain manifests itself most consummately when it is intensified; it fulfills itself most deeply by gradually reenforcing its own fortitude. To make sense of pain, therefore, we must understand the nature of its 'movement': and in Benjamin's metaphor of the "navigable river" - its flow. In what follows, I develop Benjamin's idea of the nature of pain as manifested in the internal law of its ,ow in two other of Benjamin's texts: 'Berlin Childhood Around 1900' (1934) and 'Thought Figures' (1933).
One of the cruxes of Walter Benjamin’s work is the tension between an indebting and an expiating "memoria", i. e. the afflicting and the salvific insistence of history within the present moment. On the one hand, memory inscribes itself onto spaces and bodies in the violent and painful fashion of Kafka's "Penal Colony" apparatus. On the other hand, it can, in the form of rememoration ('Eingedenken'), sublate these very inscriptions. This sublation usually involves some form of redemptive, timely (re-)verbalization, but Benjamin’s conception of it varies. To gain a better insight into this inherent, varying tension, the article will take a closer look at the connection between pain, memory and law-positing violence in some Benjaminian texts, occasionally relating them to the historical background of his discussion.
Walter Benjamin had a revealing fascination with the legend of a Chinese artist who entered his painting and disappeared in it. In his writings this character becomes an emblematic figure that enables the philosopher to discuss the nature of representation in its various infections (in games and in painting, in theater and in cinema); to explore the status of the image and of the threshold that simultaneously separates and connects image and reality; to analyse the different bodily (i. e. "aesthetic") attitudes of the beholder in his/her close or distant relationship to the image; to investigate the manifold implications of empathy ('Einfühlung ') toward the figurative world; and finally, to approach a peculiar kind of dialectics, namely the "Chinese". My paper aims at considering such varied aspects in Benjamin's interpretation of the Chinese painter, understanding it as a true "dialectical image" that in its 'non-coincidentia oppositorum' provokes not only significant hermeneutic oscillations, but even a radical inversion of its fundamental meaning.
If we take Benjamin's definitions to their logical conclusion, then the monad and the reproduced copy are set unequivocally into binary opposition, as we, the masses capable and most needful of action, are implicitly denied the potential for liberation through aesthetic experience. This denial could not have been his long-term intention. When we take into account the breadth of his writings in response to Fascism, and we look at the artistic movements, Dada in particular, that Benjamin defines as 'politicizing art,' it seems as though we risk too narrow a reading of Benjamin's theories by assuming the aura can be, or must be, done away with. Rather, I would argue that this moment of auratic interaction is crucial to effectively politicizing art at all. Mechanically-produced art, in order to function politically, must allow its audience the space necessary to step back, awaken their 'Geistesgegenwart', and take action 'before' the present moment is finished and past. The elimination of aura - as per Benjamin’s own definitions of aura - neuters the interaction this awakening requires. While Benjamin provides the framework and asks the right questions, when determining what will allow his definitions to realize their aims most fully, I submit that he draws his line in the wrong place.
The flourishing of literature and thought during the age of Goethe may have inspired German nationalism in the 1930s, but Walter Benjamin identified other values in the period worth defending. 'Deutsche Menschen' is a short collection of edited letters by well-known German authors which Benjamin published in 1936 under the pseudonym Detlef Holz in order to hide his Jewish identity. In his inscription to Scholem's copy of the book, Benjamin wrote, "May you, Gerhard, find a chamber in this ark - which I built when the Fascist flood started to rise - for the memories of your youth," and in his sister’s copy Benjamin wrote, "This ark, built after a Jewish model, for Dora - From Walter." This essay considers what Benjamin may have meant by those inscriptions. Looking beyond discussions of "German," "Jewish," and even "German-Jewish" identity, this essay explores Benjamin's descriptions of his letter collection, asking how he conceptualized and framed it at first and how it may have changed between 1931 and 1936. The categories of tradition and agency will be my focus, which I will develop in the context of Benjamin's other writings and his particular interests in quotation and materialism. &e formation and reception of 'Deutsche Menschen' reveal a complex, ambitious project that combines many of Benjamin's ideas and goals.
Two alternative hypotheses – referred to as opportunity- and stigma-based behavior – suggest that the magnitude of the link between unemployment and crime also depends on preexisting local crime levels. In order to analyze conjectured nonlinearities between both variables, we use quantile regressions applied to German district panel data. While both conventional OLS and quantile regressions confirm the positive link between unemployment and crime for property crimes, results for assault differ with respect to the method of estimation. Whereas conventional mean regressions do not show any significant effect (which would confirm the usual result found for violent crimes in the literature), quantile regression reveals that size and importance of the relationship are conditional on the crime rate. The partial effect is significantly positive for moderately low and median quantiles of local assault rates.
Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species’ threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project – and avert – future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups – including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems – www.predicts.org.uk). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.
With Architecture Since 1400 another volume has been added to the list of authoritative surveys of architectural history published in recent years. With 30 bit-like chapters and some 300 illustrations, this book is an ambitious attempt to write a global history of architecture that focuses on the arrival of modernity. The central idea of this survey is the shift away from the Weberian approach that views modernization as emanating from the West. Instead, in this book modern architecture is rewritten according to a global approach that allows for multiple perspectives in a multipolar world. This decentring approach is also pivotal for other parts of the book. For example, there is the much-needed effort to include women in the canon. In addition, the author exchanges a stylistic history for a social history and combines this with a narrative that maps the agents of the built environment, thus complementing the narrative of the genius-architect with that of the role played by clients, patrons and critics. In this way, Lina Bo Bardi or Zaha Hadid not only take their place next to Le Corbusier or Brunelleschi, but in addition Eleanor of Toledo is mentioned as an influential sixteenth-century ruler next to her husband Cosimo I, and Hardwick Hall in England is now considered the outcome of the cooperation between the architect Robert Smythson and the landowner Bess of Hardwick.
Heterogenous subtypes of breast cancer need to be analyzed separately. Pooling of datasets can provide reasonable sample sizes but dataset bias is an important concern. We assembled a combined dataset of 579 Affymetrix microarrays from triple negative breast cancer (TNBC) in Gene Expression Omnibus (GEO) series GSE31519. We developed a method for selecting comparable datasets and to control for the amount of dataset bias of individual probesets.
"I Am a Hottentot" : africanist mimicry and green xenophilia in Hans Paasche and Karen Blixen
(2014)
Claims that industrialized western countries must reform their environmental practices have often been made with reference to less-developed non-western societies living in greater "harmony" or "balance" with the natural world. Examples of what I call green xenophilia (from the Greek "xenos", meaning strange, unknown or foreign, and "philia", meaning love or attraction), are myriad, wide-ranging and culturally dispersed. They range from the appearance of the iconic "crying Indian" in anti-pollution TV and newspaper spots in the months leading up to the first Earth Day on April 22 1970 to numerous environmentalist individuals' and groups' use of the fabricated "Chief Seattle's Speech" as an authoritative touchstone of ecological consciousness, and from the British Schumacher College's endorsement of India as a source of simplicity, holism, humility, vegetarianism etc. to leading deep ecologists' advocacy of East Asian religions (especially Buddhism, Jainism and Taoism) as "biocentric" alternatives to "anthropocentric" Christianity (Rolston 1987; Dunaway 2008; Krupat 2011; Corrywright 2010). Invocations of non-western cultures, identities and worldviews have proved potent heuristic devices, enabling greens both to critique the status quo and to gesture (however schematically) towards the possibility of alternatives. Pervasive media-borne ideas and images like "the Green Tibet" (Huber 1997) and "the ecological Indian" (Krech 1999) have given environmentalist ideas about the good life physical incarnation, making them seem less remote and abstract. Yet the prevalence of xenophile dis course has also made environmentalism vulnerable to recurrent accusations of romantic primitivism, orientalism and exoticism, as western greens have sometimes (though not always) appeared to buttress traditional socio-cultural norms in the very act of challenging them (Guha 1989; Lohmann 1993; Bartholomeusz 1998). What is gained and what is risked when western greens speak about, with, for or as "the other"? In this essay I engage with two early-twentieth-century North European writers, the German Hans Paasche (1881-1921) and the Dane Karen Blixen (1885-1962), whose works bring this question to the forefront. Critical of European industrialization, and awkwardly positioned vis-a-vis their upper-class social milieus, Paasche and Blixen wrote as self-made "Africans", testing the limits between colonialism, anti-colonialism and emergent forms of environmentalism and green" lifestyle reform. More precisely, Paasche in "Die Forschungsreise des Afrikaners Lukanga Kukara ins Innerste Deutschland" ("The African Lukanga Mukara's Research Joumey into the Innermost of Germany" (1912-1913) and Blixen in "Out of Africa" (1937) deploy the ambiguous form of mimicry that Susan Gubar labels "racechange", impersonating or appropriating culturally other voices and perspectives on animals, food, physical embodiment and human-natural relations (Gubar 1997). Paasche and Blixen, I argue, used their considerable intercultural insight to construct images of Africa that they hoped would stand in redemptive contrast to the humanly and environmentally ruinous beliefs and practices of European modernity. I am interested in the acts of ethnic and textual self-alienation that these writers perform because they highlight the discursive, ethical and political ambiguities of green xenophilia - ambiguities that can be explored from different positions within the developing field of ecocritical studies.
The present article analyzes a prominent yet relatively understudied contact space among Native American, New Zealand Maori, and aboriginal Taiwanese literatures: the struggle of indigenous peoples to negotiate optimal relationships between themselves and the natural world, particularly in light of capitalist modernity and globalization. Many indigenous narratives draw sharp distinctions between native peoples and outsiders, predictably portraying the former as protectors and the latter as destroyers of both nature and indigenous local cultures. The Native American Chickasaw writer Linda Hogan's (1947-) novel 'People of the Whale' (2008), the Maori writer Patricia Grace's (1937-) novel 'Patiki' (1986), and the aboriginal Taiwanese writer Topas Tamapima's short story "Zuihou de lieren" are no exception. But these texts also problematize notions of the so-called "ecological native." They do so most conspicuously by revealing the ambiguous relationships those peoples believed closest to nature have with the nonhuman world, that is to say their environmental ambiguity ('ecoambiguity') (Thornber 2012).
Ecocriticism started out in the early 1990s in the framework of American literary studies - in the Anglo sense that equates "America" with the "United States." In fact, the new field's first professional organization, the Association for the Study of Literature and the Environment, was founded as an offshoot of academic interest focused on a particular region of the United States, in the backroom of a casino in Reno, Nevada, during the 1992 annual convention of the Western Literature Association. During its first decade, the bulk of ecocritical attention focused on American literature as shaped by Thoreau and British literature as shaped by Wordsworth - a limited but powerful concentration on nature writing in the genres of poetry, nonfiction prose, and the noveI, with particular attention to Native American literature. By the turn of the millennium, in a story that has by now been told repeatedly, interest in the literature-environment nexus had grown and diversified enough that ecocriticism almost literally exploded into a much broader research area encompassing multiple historical periods (from the Middle Ages to postmodernism), genres (from poetry to the graphic novel and narrative film), and regions: the Caribbean, Latin America, East Asia, and Western Europe all emerged as new areas of ecocritical exploration. New encounters between postcolonial theory and ecocritical analysis proved particularly productive for both fields: linking historical exploration and political ecology with literary analysis, the emergent "poco-eco" matrix opened new perspectives on the connections and disjunctures between imperialism, ecological crisis, and conservation. Over the last few years, the concept of "Environmental Humanities" has increasingly co me to accompany and to superimpose itself as an umbrella term on ecocriticism and comparable research areas in neighboring disciplines: environmental history, environmental anthropology, environmental philosophy, cultural geography, and political ecology. Driven by the impulse to connect environmental research across the humanities, to justify humanistic research at institutions often prone to cut first in the humanities, and to bring the knowledge generated through humanistic research into the public sphere, environmentally oriented scholars have used the term "Environmental Humanities" as a shorthand for what they hope will be a new vision of their discipline. As of this writing, the concept remains somewhat more aspirational than real. While ecocritics and environmental philosophers have long collaborated in Australia, and environmental historians and ecocritics sometimes collaborate in the United States, the disciplines that make up the Environmental Humanities have to date largely pursued their own disciplinary trajectories. But there are signs that the tide may have begun to turn. Various universities and research organizations have started programs in the field. The Swedish environmental historian Sverker Sörlin published a brief outline of the new interdisciplinary matrix in the journal 'BioScience' in 2012, and a longer manifesto followed from the editorial collective of the newly established journal 'Environmental Humanities' at Macquarie University in Australia (Rose et al. 2012). Another journal focusing on the environmental humanities began publication in early 2014 from the University of Oregon under the title 'Resilience'.
Background and Purpose. Leukocyte migration into alveolar space plays a critical role in pulmonary inflammation resulting in lung injury. Acute ethanol (EtOH) exposure exerts anti-inflammatory effects. The clinical use of EtOH is critical due to its side effects. Here, we compared effects of EtOH and ethyl pyruvate (EtP) on neutrophil adhesion and activation of cultured alveolar epithelial cells (A549). Experimental Approach. Time course and dose-dependent release of interleukin- (IL-) 6 and IL-8 from A549 were measured after pretreatment of A549 with EtP (2.5–10 mM), sodium pyruvate (NaP, 10 mM), or EtOH (85–170 mM), and subsequent lipopolysaccharide or IL-1beta stimulation. Neutrophil adhesion to pretreated and stimulated A549 monolayers and CD54 surface expression were determined. Key Results. Treating A549 with EtOH or EtP reduced substantially the cytokine-induced release of IL-8 and IL-6. EtOH and EtP (but not NaP) reduced the adhesion of neutrophils to monolayers in a dose- and time-dependent fashion. CD54 expression on A549 decreased after EtOH or EtP treatment before IL-1beta stimulation. Conclusions and Implications. EtP reduces secretory and adhesive potential of lung epithelial cells under inflammatory conditions. These findings suggest EtP as a potential treatment alternative that mimics the anti-inflammatory effects of EtOH in early inflammatory response in lungs.
Malignant gliomas are intrinsic brain tumors with a dismal prognosis. They are well-adapted to hypoxic conditions and poorly immunogenic. NKG2D is one of the major activating receptors of natural killer (NK) cells and binds to several ligands (NKG2DL).
Here we evaluated the impact of miRNA on the expression of NKG2DL in glioma cells including stem-like glioma cells. Three of the candidate miRNA predicted to target NKG2DL were expressed in various glioma cell lines as well as in glioblastomas in vivo: miR-20a, miR-93 and miR-106b. LNA inhibitor-mediated miRNA silencing up-regulated cell surface NKG2DL expression, which translated into increased susceptibility to NK cell-mediated lysis. This effect was reversed by neutralizing NKG2D antibodies, confirming that enhanced lysis upon miRNA silencing was mediated through the NKG2D system. Hypoxia, a hallmark of glioblastomas in vivo, down-regulated the expression of NKG2DL on glioma cells, associated with reduced susceptibility to NK cell-mediated lysis. This process, however, was not mediated through any of the examined miRNA. Accordingly, both hypoxia and the expression of miRNA targeting NKG2DL may contribute to the immune evasion of glioma cells at the level of the NKG2D recognition pathway. Targeting miRNA may therefore represent a novel approach to increase the immunogenicity of glioblastoma.
The Cueva del Azufre in Tabasco, Mexico, is a nutrient-rich cave and its inhabitants need to cope with high levels of dissolved hydrogen sulfide and extreme hypoxia. One of the successful colonizers of this cave is the poeciliid fish Poecilia mexicana, which has received considerable attention as a model organism to examine evolutionary adaptations to extreme environmental conditions. Nonetheless, basic ecological data on the endemic cave molly population are still missing; here we aim to provide data on population densities, size class compositions and use of different microhabitats. We found high overall densities in the cave and highest densities at the middle part of the cave with more than 200 individuals per square meter. These sites have lower H2S concentrations compared to the inner parts where most large sulfide sources are located, but they are annually exposed to a religious harvesting ceremony of local Zoque people called La Pesca. We found a marked shift in size/age compositions towards an overabundance of smaller, juvenile fish at those sites. We discuss these findings in relation to several environmental gradients within the cave (i.e., differences in toxicity and lighting conditions), but we also tentatively argue that the annual fish harvest during a religious ceremony (La Pesca) locally diminishes competition (and possibly, cannibalism by large adults), which is followed by a phase of overcompensation of fish densities.
The Future of the Noosphere
(2014)
In this article, a Koselleckian approach to the issue of time will be employed. In Koselleck's view, modernity has been characterized by a multiplicity of synchronous times, or as Helge Jordheim puts it, by "multiple temporalities". By temporality, Koselleck means something different than epochs or periodizations. More precisely, Jordheim asserts, Koselleck uses this term to reach for experiences of time, such as "progress, decadence, acceleration, or delay, the 'not yet' and the 'no longer', the 'earlier' or 'later than', the 'too early' and the 'too late', situation and the duration". Especially pertinent for this article is Koselleck's category of a horizon of expectations (Erwartungshorizont), understood as perceived prospects for the future. In both the noosphere and the Anthropocene discussion, the notion of an Age of Man seems to merge different timescales into one another, or, as stated by one of the most prominent scientists in the early debate, "The division of historical and geological time is levelled out for us". This article examines the temporality implied in the noosphere concept in order to formulate a specific question regarding the Anthropocene. The article is thus intended to contribute to the on-going examination of the Anthropocene concept by way of historicising its temporality.
For more than two decades, the National Planning Office for Philosophy and Social Sciences (NPOPSS) has been managing official funding of social science research in China under the orbit of the Communist Party of China’s (CPC) propaganda system. By focusing on “Major Projects”, the most prestigious and well-funded program initiated by the NPOPSS in 2004, this contribution outlines the political and institutional ramifications of this line of official funding and attempts to identify larger shifts during the past decade in the “ideologics” of official social science research funding – the changing ideological circumscriptions of research agendas in the more narrow sense of echoing party theory and rhetoric and – in the broader sense – of adapting to an increasingly dominant official discourse of cultural and national self-assertion. To conclude, this article offers reflections on the potential repercussions of these shifts for international academic collaboration.
In my paper I take issue with proponents of ‘intersectionality’ which believe that a theoretical concept cannot/should not be detached from its original context of invention. Instead, I argue that the traveling of theory in a global context automatically involves appropriations, amendment and changes in response to the original meaning. However, I reject the idea that ‘intersectionality’ can be used as a freefloating signifier; on the contrary, it has to be embedded in the respective (historical, social, cultural) context in which it is used. I will start by mapping some of the current debates engaging with the pros and cons of the global implementation of the concept (the controversy about master categories, the dispute about the centrality of ‘race’, and the argument about the amendment of categories). I will then turn to my own use of ‘intersectionality’ as a methodological tool (elaborated in Lutz and Davis 2005). Here, we shifted attention from how structures of racism, class discrimination and sexism determine individuals’ identities and practices to how individuals ongoingly and flexibly negotiate their multiple and converging identities in the context of everyday life. Introducing the term doing intersectionality we explored how individuals creatively and often in surprising ways draw upon various aspects of their multiple identities as a resource to gain control over their lives.
In my paper I will show how ‘gender’ or ‘ethnicity’ are invariably linked to structures of domination, but can also mobilize or deconstruct disempowering discourses, even undermine and transform oppressive practices.
Obstetrical care as a matter of time: ultrasound screening in anticipatory regimes of pregnancy
(2014)
This article explores the ways in which ultrasound screening influences the temporal dimensions of prevention in the obstetrical management of pregnancy. Drawing on praxeographic perspectives and empirically based on participant observation of ultrasound examinations in obstetricians’ offices, it asks how ultrasound scanning facilitates anticipatory modes of pregnancy management, and investigates the entanglement of different notions of time and temporality in the highly risk-oriented modes of prenatal care in Germany. Arguing that the paradoxical temporality of prevention – acting now in the name of the future – is intensified by ultrasound screening, I show how the attribution of risk regarding foetal growth in prenatal check-ups is based on the fragmentation of procreative time and ask how time standards come into play, how pregnancy is located in calendrical time, and how notions of foetal time and the everyday life times of pregnant women clash during negotiations between obstetricians and pregnant women about the determination of the due date. By analysing temporality as a practical accomplishment via technological devices such as ultrasound, the paper contributes to debates in feminist STS studies on the role of time in reproduction technologies and the management of pregnancy and birth in contemporary societies.
Based on a non-rigorous formalism called the “cavity method”, physicists have made intriguing predictions on phase transitions in discrete structures. One of the most remarkable ones is that in problems such as random k-SAT or random graph k-coloring, very shortly before the threshold for the existence of solutions there occurs another phase transition called condensation [Krzakala et al., PNAS 2007]. The existence of this phase transition seems to be intimately related to the difficulty of proving precise results on, e. g., the k-colorability threshold as well as to the performance of message passing algorithms. In random graph k-coloring, there is a precise conjecture as to the location of the condensation phase transition in terms of a distributional fixed point problem. In this paper we prove this conjecture, provided that k exceeds a certain constant k0.
In order to achieve climate change mitigation, long-term decisions are required that must be reconciled with other societal goals that draw on the same resources. For example, ensuring food security for a growing population may require an expansion of crop land, thereby reducing natural carbon sinks or the area available for bio-energy production. Here, we show that current impact-model uncertainties pose an important challenge to long-term mitigation planning and propose a new risk-assessment and decision framework that accounts for competing interests.
Based on cross-sectorally consistent simulations generated within the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP) we discuss potential gains and limitations of additional irrigation and trade-offs of the expansion of agricultural land as two possible response measures to climate change and growing food demand. We describe an illustrative example in which the combination of both measures may close the supply demand gap while leading to a loss of approximately half of all natural carbon sinks.
We highlight current limitations of available simulations and additional steps required for a comprehensive risk assessment.
Noise-induced hearing loss is one of the most common auditory pathologies, resulting from overstimulation of the human cochlea, an exquisitely sensitive micromechanical device. At very low frequencies (less than 250 Hz), however, the sensitivity of human hearing, and therefore the perceived loudness is poor. The perceived loudness is mediated by the inner hair cells of the cochlea which are driven very inadequately at low frequencies. To assess the impact of low-frequency (LF) sound, we exploited a by-product of the active amplification of sound outer hair cells (OHCs) perform, so-called spontaneous otoacoustic emissions. These are faint sounds produced by the inner ear that can be used to detect changes of cochlear physiology. We show that a short exposure to perceptually unobtrusive, LF sounds significantly affects OHCs: a 90 s, 80 dB(A) LF sound induced slow, concordant and positively correlated frequency and level oscillations of spontaneous otoacoustic emissions that lasted for about 2 min after LF sound offset. LF sounds, contrary to their unobtrusive perception, strongly stimulate the human cochlea and affect amplification processes in the most sensitive and important frequency range of human hearing.
BACKGROUND: Acetogenic bacteria are able to use CO2 as terminal electron acceptor of an anaerobic respiration, thereby producing acetate with electrons coming from H2. Due to this feature, acetogens came into focus as platforms to produce biocommodities from waste gases such as H2+CO2 and/or CO. A prerequisite for metabolic engineering is a detailed understanding of the mechanisms of ATP synthesis and electron-transfer reactions to ensure redox homeostasis. Acetogenesis involves the reduction of CO2 to acetate via soluble enzymes and is coupled to energy conservation by a chemiosmotic mechanism. The membrane-bound module, acting as an ion pump, was of special interest for decades and recently, an Rnf complex was shown to couple electron flow from reduced ferredoxin to NAD+ with the export of Na+ in Acetobacterium woodii. However, not all acetogens have rnf genes in their genome. In order to gain further insights into energy conservation of non-Rnf-containing, thermophilic acetogens, we sequenced the genome of Thermoanaerobacter kivui.
RESULTS: The genome of Thermoanaerobacter kivui comprises 2.9 Mbp with a G+C content of 35% and 2,378 protein encoding orfs. Neither autotrophic growth nor acetate formation from H2+CO2 was dependent on Na+ and acetate formation was inhibited by a protonophore, indicating that H+ is used as coupling ion for primary bioenergetics. This is consistent with the finding that the c subunit of the F1FO ATP synthase does not have the conserved Na+ binding motif. A search for potential H+-translocating, membrane-bound protein complexes revealed genes potentially encoding two different proton-reducing, energy-conserving hydrogenases (Ech).
CONCLUSIONS: The thermophilic acetogen T. kivui does not use Na+ but H+ for chemiosmotic ATP synthesis. It does not contain cytochromes and the electrochemical proton gradient is most likely established by an energy-conserving hydrogenase (Ech). Its thermophilic nature and the efficient conversion of H2+CO2 make T. kivui an interesting acetogen to be used for the production of biocommodities in industrial micobiology. Furthermore, our experimental data as well as the increasing number of sequenced genomes of acetogenic bacteria supported the new classification of acetogens into two groups: Rnf- and Ech-containing acetogens.
Biodiversity is unevenly distributed on Earth and hotspots of biodiversity are often associated with areas that have undergone orogenic activity during recent geological history (i.e. tens of millions of years). Understanding the underlying processes that have driven the accumulation of species in some areas and not in others may help guide prioritization in conservation and may facilitate forecasts on ecosystem services under future climate conditions. Consequently, the study of the origin and evolution of biodiversity in mountain systems has motivated growing scientific interest. Despite an increasing number of studies, the origin and evolution of diversity hotspots associated with the Qinghai-Tibetan Plateau (QTP) remains poorly understood. We review literature related to the diversification of organisms linked to the uplift of the QTP. To promote hypothesis-based research, we provide a geological and palaeoclimatic scenario for the region of the QTP and argue that further studies would benefit from providing a complete set of complementary analyses (molecular dating, biogeographic, and diversification rates analyses) to test for a link between organismic diversification and past geological and climatic changes in this region. In general, we found that the contribution of biological interchange between the QTP and other hotspots of biodiversity has not been sufficiently studied to date. Finally, we suggest that the biological consequences of the uplift of the QTP would be best understood using a meta-analysis approach, encompassing studies on a variety of organisms (plants and animals) from diverse habitats (forests, meadows, rivers), and thermal belts (montane, subalpine, alpine, nival). Since the species diversity in the QTP region is better documented for some organismic groups than for others, we suggest that baseline taxonomic work should be promoted.
The LPJ-GUESS dynamic vegetation model uniquely combines an individual- and patch-based representation of vegetation dynamics with ecosystem biogeochemical cycling from regional to global scales. We present an updated version that includes plant and soil N dynamics, analysing the implications of accounting for C–N interactions on predictions and performance of the model. Stand structural dynamics and allometric scaling of tree growth suggested by global databases of forest stand structure and development were well reproduced by the model in comparison to an earlier multi-model study. Accounting for N cycle dynamics improved the goodness of fit for broadleaved forests. N limitation associated with low N-mineralisation rates reduces productivity of cold-climate and dry-climate ecosystems relative to mesic temperate and tropical ecosystems. In a model experiment emulating free-air CO2 enrichment (FACE) treatment for forests globally, N limitation associated with low N-mineralisation rates of colder soils reduces CO2 enhancement of net primary production (NPP) for boreal forests, while some temperate and tropical forests exhibit increased NPP enhancement. Under a business-as-usual future climate and emissions scenario, ecosystem C storage globally was projected to increase by ca. 10%; additional N requirements to match this increasing ecosystem C were within the high N supply limit estimated on stoichiometric grounds in an earlier study. Our results highlight the importance of accounting for C–N interactions in studies of global terrestrial N cycling, and as a basis for understanding mechanisms on local scales and in different regional contexts.
Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in Northern Australia. However, how such changes affect the soil–atmosphere exchange of nitrous oxide (N2O), nitric oxide (NO) and dinitrogen (N2) is still 5 not well explored. By incubating intact soil cores from four sites (3 savanna, 1 pasture) under controlled soil temperatures (ST) and soil moisture (SM) we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2). Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emission were very low (< 7.0± 5.0 μgNO-Nm−2 h−1; < 0.0± 1.4 μgN2O-Nm−2 h−1) or in case of N2O, even a net soil uptake was observed. Substantial NO (max: 306.5 μgNm−2 h−1) and relatively small N2O pulse emissions (max: 5.8±5.0 μgNm−2 h−1) were recorded following soil wetting, but these pulses were short-lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was dominated by N2 emissions (82.4–99.3% of total N lost), although NO emissions contributed almost 43.2% at 50% SM and 30 °C ST. N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. Emissions were controlled by SM and ST for N2O and CO2, ST and pH for NO, and SM and pH for N2.
Strong seasonal variability of hygric and thermal soil conditions are a defining environmental feature in northern Australia. However, how such changes affect the soil–atmosphere exchange of nitrous oxide (N2O), nitric oxide (NO) and dinitrogen (N2) is still not well explored. By incubating intact soil cores from four sites (three savanna, one pasture) under controlled soil temperatures (ST) and soil moisture (SM) we investigated the release of the trace gas fluxes of N2O, NO and carbon dioxide (CO2). Furthermore, the release of N2 due to denitrification was measured using the helium gas flow soil core technique. Under dry pre-incubation conditions NO and N2O emissions were very low (<7.0 ± 5.0 μg NO-N m−2 h−1; <0.0 ± 1.4 μg N2O-N m−2 h−1) or in the case of N2O, even a net soil uptake was observed. Substantial NO (max: 306.5 μg N m−2 h−1) and relatively small N2O pulse emissions (max: 5.8 ± 5.0 μg N m−2 h−1) were recorded following soil wetting, but these pulses were short lived, lasting only up to 3 days. The total atmospheric loss of nitrogen was generally dominated by N2 emissions (82.4–99.3% of total N lost), although NO emissions contributed almost 43.2% to the total atmospheric nitrogen loss at 50% SM and 30 °C ST incubation settings (the contribution of N2 at these soil conditions was only 53.2%). N2O emissions were systematically higher for 3 of 12 sample locations, which indicates substantial spatial variability at site level, but on average soils acted as weak N2O sources or even sinks. By using a conservative upscale approach we estimate total annual emissions from savanna soils to average 0.12 kg N ha−1 yr−1 (N2O), 0.68 kg N ha−1 yr−1 (NO) and 6.65 kg N ha−1 yr−1 (N2). The analysis of long-term SM and ST records makes it clear that extreme soil saturation that can lead to high N2O and N2 emissions only occurs a few days per year and thus has little impact on the annual total. The potential contribution of nitrogen released due to pulse events compared to the total annual emissions was found to be of importance for NO emissions (contribution to total: 5–22%), but not for N2O emissions. Our results indicate that the total gaseous release of nitrogen from these soils is low and clearly dominated by loss in the form of inert nitrogen. Effects of seasonally varying soil temperature and moisture were detected, but were found to be low due to the small amounts of available nitrogen in the soils (total nitrogen <0.1%).
Questions about how human-environment-relations can be conceptualized in a non-dualistic way have been intensively discussed throughout the last decades. The majority of the established realist and constructivist perspectives aim at explaining a given situation by analytically dissecting it. Unfortunately, such an interactionist perspective systematically reproduces the dualistic division between humans, environment and nature.
In contrast, this paper offers a transactive perspective origin in classical pragmatism and discusses its meta-theoretical consequences for human-environment-research. A transactionist perspective interprets the world as a flow of unique and entangled events. Instead of ontologically separating humans and environment, it advocates to look at their relations as being part of a "connatural world". Such a point of view raises new ethical and political questions for geographical human-environment research, argues for a renaissance of ideographic methodologies and hints to a fruitful unity of geographical inquiry.
The prediction of climate on time scales of years to decades is attracting the interest of both climate researchers and stakeholders. The German Ministry for Education and Research (BMBF) has launched a major research programme on decadal climate prediction called MiKlip (Mittelfristige Klimaprognosen, Decadal Climate Prediction) in order to investigate the prediction potential of global and regional climate models (RCMs). In this paper we describe a regional predictive hindcast ensemble, its validation, and the added value of regional downscaling. Global predictions are obtained from an ensemble of simulations by the MPI-ESM-LR model (baseline 0 runs), which were downscaled for Europe using the COSMO-CLM regional model. Decadal hindcasts were produced for the 5 decades starting in 1961 until 2001. Observations were taken from the E-OBS data set. To identify decadal variability and predictability, we removed the long-term mean, as well as the long-term linear trend from the data. We split the resulting anomaly time series into two parts, the first including lead times of 1–5 years, reflecting the skill which originates mainly from the initialisation, and the second including lead times from 6–10 years, which are more related to the representation of low frequency climate variability and the effects of external forcing. We investigated temperature averages and precipitation sums for the summer and winter half-year. Skill assessment was based on correlation coefficient and reliability. We found that regional downscaling preserves, but mostly does not improve the skill and the reliability of the global predictions for summer half-year temperature anomalies. In contrast, regionalisation improves global decadal predictions of half-year precipitation sums in most parts of Europe. The added value results from an increased predictive skill on grid-point basis together with an improvement of the ensemble spread, i.e. the reliability.
In old and heavily weathered soils, the availability of P might be so small that the primary production of plants is limited. However, plants have evolved several mechanisms to actively take up P from the soil or mine it to overcome this limitation. These mechanisms involve the active uptake of P mediated by mycorrhiza, biotic de-occlusion through root clusters, and the biotic enhancement of weathering through root exudation. The objective of this paper is to investigate how and where these processes contribute to alleviate P limitation on primary productivity. To do so, we propose a process-based model accounting for the major processes of the carbon, water, and P cycles including chemical weathering at the global scale. Implementing P limitation on biomass synthesis allows the assessment of the efficiencies of biomass production across different ecosystems. We use simulation experiments to assess the relative importance of the different uptake mechanisms to alleviate P limitation on biomass production. We find that active P uptake is an essential mechanism for sustaining P availability on long timescales, whereas biotic de-occlusion might serve as a buffer on timescales shorter than 10 000 yr. Although active P uptake is essential for reducing P losses by leaching, humid lowland soils reach P limitation after around 100 000 yr of soil evolution. Given the generalized modelling framework, our model results compare reasonably with observed or independently estimated patterns and ranges of P concentrations in soils and vegetation. Furthermore, our simulations suggest that P limitation might be an important driver of biomass production efficiency (the fraction of the gross primary productivity used for biomass growth), and that vegetation on old soils has a smaller biomass production rate when P becomes limiting. With this study, we provide a theoretical basis for investigating the responses of terrestrial ecosystems to P availability linking geological and ecological timescales under different environmental settings.
Introduction
(2014)
BACKGROUND: Micro-RNAs (miRNA) are attributed to the systems biological role of a regulatory mechanism of the expression of protein coding genes. Research has identified miRNAs dysregulations in several but distinct pathophysiological processes, which hints at distinct systems-biology functions of miRNAs. The present analysis approached the role of miRNAs from a genomics perspective and assessed the biological roles of 2954 genes and 788 human miRNAs, which can be considered to interact, based on empirical evidence and computational predictions of miRNA versus gene interactions.
RESULTS: From a genomics perspective, the biological processes in which the genes that are influenced by miRNAs are involved comprise of six major topics comprising biological regulation, cellular metabolism, information processing, development, gene expression and tissue homeostasis. The usage of this knowledge as a guidance for further research is sketched for two genetically defined functional areas: cell death and gene expression. Results suggest that the latter points to a fundamental role of miRNAs consisting of hyper-regulation of gene expression, i.e., the control of the expression of such genes which control specifically the expression of genes.
CONCLUSIONS: Laboratory research identified contributions of miRNA regulation to several distinct biological processes. The present analysis transferred this knowledge to a systems-biology level. A comprehensible and precise description of the biological processes in which the genes that are influenced by miRNAs are notably involved could be made. This knowledge can be employed to guide future research concerning the biological role of miRNA (dys-) regulations. The analysis also suggests that miRNAs especially control the expression of genes that control the expression of genes.
Recently a considerable amount of effort has been put into quantifying how interactions of the carbon and nitrogen cycle affect future terrestrial carbon sinks. Dynamic vegetation models, representing the nitrogen cycle with varying degree of complexity, have shown diverging constraints of nitrogen dynamics on future carbon sequestration. In this study, we use LPJ-GUESS, a dynamic vegetation model employing a detailed individual- and patch-based representation of vegetation dynamics, to evaluate how population dynamics and resource competition between plant functional types, combined with nitrogen dynamics, have influenced the terrestrial carbon storage in the past and to investigate how terrestrial carbon and nitrogen dynamics might change in the future (1850 to 2100; one representative "business-as-usual" climate scenario). Single-factor model experiments of CO2 fertilisation and climate change show generally similar directions of the responses of C–N interactions, compared to the C-only version of the model as documented in previous studies using other global models. Under an RCP 8.5 scenario, nitrogen limitation suppresses potential CO2 fertilisation, reducing the cumulative net ecosystem carbon uptake between 1850 and 2100 by 61%, and soil warming-induced increase in nitrogen mineralisation reduces terrestrial carbon loss by 31%. When environmental changes are considered conjointly, carbon sequestration is limited by nitrogen dynamics up to the present. However, during the 21st century, nitrogen dynamics induce a net increase in carbon sequestration, resulting in an overall larger carbon uptake of 17% over the full period. This contrasts with previous results with other global models that have shown an 8 to 37% decrease in carbon uptake relative to modern baseline conditions. Implications for the plausibility of earlier projections of future terrestrial C dynamics based on C-only models are discussed.
Cryptochrome 1a, located in the UV/violet-sensitive cones in the avian retina, is discussed as receptor molecule for the magnetic compass of birds. Our previous immunohistochemical studies of chicken retinae with an antiserum that labelled only activated cryptochrome 1a had shown activation of cryptochrome 1a under 373 nm UV, 424 nm blue, 502 nm turquoise and 565 nm green light. Green light, however, does not allow the first step of photoreduction of oxidized cryptochromes to the semiquinone. As the chickens had been kept under ‘white’ light before, we suggested that there was a supply of the semiquinone present at the beginning of the exposure to green light, which could be further reduced and then re-oxidized. To test this hypothesis, we exposed chickens to various wavelengths (1) for 30 min after being kept in daylight, (2) for 30 min after a 30 min pre-exposure to total darkness, and (3) for 1 h after being kept in daylight. In the first case, we found activated cryptochrome 1a under UV, blue, turquoise and green light; in the second two cases we found activated cryptochrome 1a only under UV to turquoise light, where the complete redox cycle of cryptochrome can run, but not under green light. This observation is in agreement with the hypothesis that activated cryptochrome 1a is found as long as there is some of the semiquinone left, but not when the supply is depleted. It supports the idea that the crucial radical pair for magnetoreception is generated during re-oxidation.
It is common practice to use a 30-year period to derive climatological values, as recommended by the World Meteorological Organization. However this convention relies on important assumptions, of which the validity can be examined by deriving the uncertainty inherent to using a limited time-period for deriving climatological values. In this study a new method, aiming at deriving this uncertainty, has been developed with an application to precipitation for a station in Europe (Westdorpe) and one in Africa (Gulu). The weather generator framework is used to produce synthetic daily precipitation time-series that can also be regarded as alternative climate realizations. The framework consists of an improved Markov model, which shows good performance in reproducing the 5-day precipitation variability. The sub-seasonal, seasonal and the inter-annual signals are introduced in the weather generator framework by including covariates. These covariates are derived from an empirical mode decomposition analysis with an improved stability and significance assessment. Introducing covariates was found to substantially improve the monthly precipitation variability for Gulu. From the weather generator, 1,000 synthetic time-series were produced. The divergence between these time-series demonstrates an uncertainty, inherent to using a 30-year period for mean precipitation, of 11 % for Westdorpe and 15 % for Gulu. The uncertainty for precipitation 10-year return levels was found to be 37 % for both sites.
Endoscopic retrograde cholangiopancreatography (ERCP) offers an effective interventional option for treating symptomatic chronic pancreatitis. Endoscopic pancreatic sphincterotomy is performed to facilitated endoscopic treatment. Pancreatic duct strictures can be treated by inserting plastic stents, and a 10 Fr endoprosthesis is adequate in many cases. Before stent insertion, hydrostatic balloon dilation is needed in some cases. Pancreatic stones can be removed with a dormia basket, but combining ERCP and extracorporeal shockwave lithotripsy (ESWL) is often most effective.
Standard and advanced endoscopic treatment approaches are delineated in this article and include stricture dilation with a Soehendra retriever, cSEMS placement and multi-stenting.
Most available knowledge on fungal arginine metabolism is derived from studies on Saccharomyces cerevisiae, in which arginine catabolism is initiated by releasing urea via the arginase reaction. Orthologues of the S. cerevisiae genes encoding the first three enzymes in the arginase pathway were cloned from Kluyveromyces lactis and shown to functionally complement the corresponding deletion in S. cerevisiae. Surprisingly, deletion of the single K. lactis arginase gene KlCAR1 did not completely abolish growth on arginine as nitrogen source. Growth rate of the deletion mutant strongly increased during serial transfer in shake-flask cultures. A combination of RNAseq-based transcriptome analysis and 13C-15N-based flux analysis was used to elucidate the arginase-independent pathway. Isotopic 13C15N-enrichment in γ-aminobutyrate revealed succinate as the entry point in the TCA cycle of the alternative pathway. Transcript analysis combined with enzyme activity measurements indicated increased expression in the Klcar1Δ mutant of a guanidinobutyrase (EC.3.5.3.7), a key enzyme in a new pathway for arginine degradation. Expression of the K. lactis KLLA0F27995g (renamed KlGBU1) encoding guanidinobutyrase enabled S. cerevisiae to use guanidinobutyrate as sole nitrogen source and its deletion in K. lactis almost completely abolish growth on this nitrogen source. Phylogenetic analysis suggests that this enzyme activity is widespread in fungi.
The first cultural influences come out in Dobruja together with the appearance of the first German colonists, beginning from 1840 till 1891. The colonization process develops itself in three stages and colonies in places like Tulcea, Malcoci, Almagea, Ciucurova, Cogealac, Tariverde, M. Kogălniceanu and others set up as a result. The German population has created an original culture, an ethnic and spiritual communication being deeply set up, but at the same time a communication struck by the specific conditions imposed by the history of this south-eastern European area. On the other side, the Turkish invasion of Dobruja started earlier, in 1388, when it was actually defeated by Mircea cel Bătrân. In 1393 the Turks succeeded in taking Dobruja and Silistra, but in 1404 Micea cel Bătrân re-conquered the greatest part of these regions. Many Turkish and Tartars moved into Dobruja during the long period of Ottoman rule. The 19th century ethnographic maps show a mainly Turkish population in the area of modern day Dobruja, Tartars and Turks in the southern part of Dobruja and Romanians dominating the north of Dobruja. The paper aims at presenting aspects regarding these two different identities and cultures which are to be found in Dobruja, as well as their integration process within the Romanian Dobrujan modern society.