Refine
Year of publication
- 2020 (2163) (remove)
Document Type
- Article (1408)
- Part of Periodical (253)
- Preprint (169)
- Doctoral Thesis (127)
- Working Paper (99)
- Part of a Book (58)
- Book (31)
- Conference Proceeding (6)
- Master's Thesis (3)
- Review (3)
Language
- English (2163) (remove)
Is part of the Bibliography
- no (2163) (remove)
Keywords
- taxonomy (87)
- new species (50)
- Spracherwerb (33)
- Sprachtest (33)
- COVID-19 (23)
- morphology (20)
- inflammation (18)
- ECB (16)
- SARS-CoV-2 (15)
- biodiversity (15)
Institute
- Medizin (636)
- Physik (248)
- Wirtschaftswissenschaften (157)
- Biowissenschaften (149)
- Frankfurt Institute for Advanced Studies (FIAS) (149)
- Sustainable Architecture for Finance in Europe (SAFE) (117)
- Informatik (115)
- Biochemie, Chemie und Pharmazie (97)
- Center for Financial Studies (CFS) (72)
- House of Finance (HoF) (62)
Direct nanoscopic observation of plasma waves in the channel of a graphene field-effect transistor
(2020)
Plasma waves play an important role in many solid-state phenomena and devices. They also become significant in electronic device structures as the operation frequencies of these devices increase. A prominent example is field-effect transistors (FETs), that witness increased attention for application as rectifying detectors and mixers of electromagnetic waves at gigahertz and terahertz frequencies, where they exhibit very good sensitivity even high above the cut-off frequency defined by the carrier transit time. Transport theory predicts that the coupling of radiation at THz frequencies into the channel of an antenna-coupled FET leads to the development of a gated plasma wave, collectively involving the charge carriers of both the two-dimensional electron gas and the gate electrode. In this paper, we present the first direct visualization of these waves. Employing graphene FETs containing a buried gate electrode, we utilize near-field THz nanoscopy at room temperature to directly probe the envelope function of the electric field amplitude on the exposed graphene sheet and the neighboring antenna regions. Mapping of the field distribution documents that wave injection is unidirectional from the source side since the oscillating electrical potentials on the gate and drain are equalized by capacitive shunting. The plasma waves, excited at 2 THz, are overdamped, and their decay time lies in the range of 25-70 fs. Despite this short decay time, the decay length is rather long, i.e., 0.3-0.5 μm, because of the rather large propagation speed of the plasma waves, which is found to lie in the range of 3.5-7 × 106 m/s, in good agreement with theory. The propagation speed depends only weakly on the gate voltage swing and is consistent with the theoretically predicted 1/4 power law.
Management of decompensated cirrhosis is currently geared towards the treatment of complications once they occur. To date there is no established disease-modifying therapy aimed at halting progression of the disease and preventing the development of complications in patients with decompensated cirrhosis. The design of clinical trials to investigate new therapies for patients with decompensated cirrhosis is complex. The population of patients with decompensated cirrhosis is heterogeneous (i.e., different etiologies, comorbidities and disease severity), leading to the inclusion of diverse populations in clinical trials. In addition, primary endpoints selected for trials that include patients with decompensated cirrhosis are not homogeneous and at times may not be appropriate. This leads to difficulties in comparing results obtained from different trials. Against this background, the LiverHope Consortium organized a meeting of experts, the goal of which was to develop recommendations for the design of clinical trials and to define appropriate endpoints, both for trials aimed at modifying the natural history and preventing progression of decompensated cirrhosis, as well as for trials aimed at managing the individual complications of cirrhosis.
Many species of plants and a few species of animals are believed to have resulted from hybridization of parental species, and the ability of species to occasionally hybridize in captivity and in nature is even more widespread. In the present study, we describe a hybridization experiment conducted in the laboratory between the sexually dimorphic Automeris io (Fabricius), a widespread, variable species ranging from Canada to Costa Rica, and its congener A. louisiana (Ferguson and Brou), a more local, sexually monomorphic species (Lepidoptera: Saturniidae). The A. louisiana populations occur in a highly specialized habitat—the coastal marshland along the Gulf of Mexico in Louisiana and Texas and is nested inside the broad distribution of A. io, demonstrating strong differences from the latter in its ecology and morphology. No natural hybridization between the two species has been described. While the separate species status of A. io and A. louisiana is supported by morphology and ecology of their populations, we were able to create a hybrid lineage in the laboratory and maintained it for three generations. The hybrids were phenotypically intermediate between the parental species. Under a stricter reading of the biological species concept, such an ability to hybridize would be interpreted by some as a sign of conspecificity. Our experiments once again demonstrate the complexity of ‘species’ as a concept, which may need major redefinition in the popular interpretation of sciences.
Capparis macrantha Souvannakhoummane, Fici & Lanorsavanh sp. nov., a new shrub species characterized by erect or ascending habit, stipular thorns, large lanceolate-elliptic leaves and large flowers in supra-axillary rows, is described and illustrated from the deciduous forest in Nam Kading National Protected Area (central Lao PDR). The new species belongs to Capparis sect. Monostichocalyx Radlk. and is morphologically similar to C. radula Gagnep., a shrub widespread in the Indochinese area, differing in the shorter, straight stipular thorns, larger leaves, larger sepals and petals, higher number of stamens with longer filaments and longer gynophore and ovary. Its affinities with related taxa are discussed and a key is provided for the species of Capparis L. known from Lao PDR. The conservation status of the new species is provisionally assessed as Vulnerable (VU D1).
High-pressure single-crystal to 20 GPa and powder diffraction measurements to 50 GPa, show that the structure of Pb2SnO4 strongly distorts on compression with an elongation of one axis. A structural phase transition occurs between 10 GPa and 12 GPa, with a change of space group from Pbam to Pnam. The resistivity decreases by more than six orders of magnitude when pressure is increased from ambient conditions to 50 GPa. This insulator-to-semiconductor transition is accompanied by a reversible appearance change from transparent to opaque. Density functional theory-based calculations show that at ambient conditions the channels in the structure host the stereochemically-active Pb 6s2 lone electron pairs. On compression the lone electron pairs form bonds between Pb2+ ions. Also provided is an assignment of irreducible representations to the experimentally observed Raman bands.
The recruitment processes and resulting distribution pattern of bird-dispersed Canary Island Date Palm, Phoenix canariensis (family Arecaceae) in a riverine forest setting are described. All palms on a near-urban peninsula of the Murrumbidgee River near Hay, New South Wales were GPS mapped and classified into height-dependent age categories. The distribution of the plants was examined spatially in relation to possible source palms and in relation to elevation with regard to flooding levels. Successful recruitment is subject to a range of environmental parameters, primarily palatability to vectors and seedling mortality due to lack of moisture, frost or grazing by herbivores. If a seedling survives that critical period of the first 18 months, long-term success is (almost) guaranteed, unless catastrophic events (bushfires, prolonged flooding) intervene. Based on the findings, a conceptual model for the recruitment of Phoenix canariensis palms is provided. Even though the palms produce fruit for much of the year (March–December), the time window for successful recruitment is restricted to a period from August to mid-September with short shoulder periods on either side.
Radiating exposures
(2020)
The brief explorations of radiation exposures presented within this essay draw primarily from nuclear art and culture and contribute to the field of nuclear aesthetics, which has long been fixated on the problem of visibility and the representation of nuclear residues. The examples draw primarily from photographic technologies and other aesthetic registers that capture visual residues of radiation. The challenges of nuclear aesthetics are also political and social. This constellation of objects and inquiries is meant to explore the fraught political, environmental, and social relations between radiation, visibility, toxicity, through the concept of exposure. They offer feminist glimpses into other ways of thinking exposure, as it develops in relation to (often imperceptible) toxicity that is not inscribed into a logic that partitions the passive victim of suffering from some pure or unaffected subject. They are examples that are both forms of exposure specific to the nuclear while also, perhaps, helping to expose more nuanced and complex ways of understanding forms of exposure that extend beyond nuclearity.
The issue of data security has become increasingly complex in the age of the internet and artificial intelligence. The developments seem to be almost unmanageable in some areas. Cooperation between jurisprudence and information technology is the only thing that can protect the individual and certain social groups from discrimination.
A new millipede species of the genus Sechelleptus Mauriès, 1980 is described and illustrated from Mayotte Island, Indian Ocean. This new species, S. arborivagus sp. nov., found on trees, looks particularly similar to the sympatric S. variabilis VandenSpiegel & Golovatch, 2007, but is much larger and has a very different ecological behavior. Phylogenetic analyses based on a concatenated dataset of the COI and 16S rRNA genes and including nine species of Spirostreptidae (including Sechelleptus, Doratogonus Attems, 1914, Bicoxidens Attems, 1928 and Spirostreptus Brandt, 1833), strongly support the monophyly of Sechelleptus. Despite the similarity of their genitalia, the molecular analyses also reveal a clear-cut genetic divergence between S. arborivagus sp. nov. and S. variabilis (22.55% for COI and 6.63% for 16SrRNA) and further suggest the presence of a higher diversity within the genus Sechelleptus on Mayotte.
A link between populism and social media is often suspected. This paper spells out a set of possible mechanisms underpinning this link: that social media changes the communication structure of the public sphere, making it harder for citizens to obtain evidence that refutes populist assumptions. By developing a model of the public sphere, four core functions of the public sphere are identified: exposing citizens to diverse information, promoting equality of deliberative opportunity, creating deliberative transparency, and producing common knowledge. A wellworking public sphere allows citizens to learn that there are genuine disagreements among citizens that are held in good faith. Social media makes it harder to gain this insight, opening the door for populist ideology.
We investigate hadronic particle spectra and flow characteristics of heavy-ion reactions in the FAIR/NICA energy range of 1 AGeV ≤ Elab ≤ 10 AGeV within a relativistic ideal hydrodynamic one-fluid approach. The particlization is realized by sampling the Cooper-Frye distribution for a grand canonical hadron gas on a hypersurface of constant energy density. Results of the hydrodynamic calculations for different underlying equations of state are presented and compared with experimental data and microscopic transport simulations. The sensitivity of the approach to physical model inputs concerning the initial state and the particlization is studied.
Virtual reality (VR) headsets offer a large and immersive workspace for displaying visualizations with stereoscopic vision, as compared to traditional environments with monitors or printouts. The controllers for these devices further allow direct three-dimensional interaction with the virtual environment. In this paper, we make use of these advantages to implement a novel multiple and coordinated view (MCV) system in the form of a vertical stack, showing tilted layers of geospatial data. In a formal study based on a use-case from urbanism that requires cross-referencing four layers of geospatial urban data, we compared it against more conventional systems similarly implemented in VR: a simpler grid of layers, and one map that allows for switching between layers. Performance and oculometric analyses showed a slight advantage of the two spatial-multiplexing methods (the grid or the stack) over the temporal multiplexing in blitting. Subgrouping the participants based on their preferences, characteristics, and behavior allowed a more nuanced analysis, allowing us to establish links between e.g., saccadic information, experience with video games, and preferred system. In conclusion, we found that none of the three systems are optimal and a choice of different MCV systems should be provided in order to optimally engage users.
Fragment-based screening has evolved as a remarkable approach within the drug discovery process both in the industry and academia. Fragment screening has become a more structure-based approach to inhibitor development, but also towards development of pathway-specific clinical probes. However, it is often witnessed that the availability, immediate and long-term, of a high quality fragment-screening library is still beyond the reach of most academic laboratories. Within iNEXT (Infrastructure for NMR, EM and X-rays for Translational research), a EU-funded Horizon 2020 program, a collection of 782 fragments were assembled utilizing the concept of “poised fragments” with the aim to facilitate downstream synthesis of ligands with high affinity by fragment ligation. Herein, we describe the analytical procedure to assess the quality of this purchased and assembled fragment library by NMR spectroscopy. This quality assessment requires buffer solubility screening, comparison with LC/MS quality control and is supported by state-of-the-art software for high throughput data acquisition and on-the-fly data analysis. Results from the analysis of the library are presented as a prototype of fragment progression through the quality control process.
Neutron-induced fission cross sections of isotopes involved in the nuclear fuel cycle are vital for the design and safe operation of advanced nuclear systems. Such experimental data can also provide additional constraints for the adjustment of nuclear model parameters used in the evaluation process, resulting in the further development of fission models. In the present work, the 237Np(n,f) cross section was studied at the EAR2 vertical beam-line at CERN's n_TOF facility, over a wide range of neutron energies, from meV to MeV, using the time-of-flight technique and a set-up based on Micromegas detectors, in an attempt to provide accurate experimental data. Preliminary results in the 200 keV – 14 MeV neutron energy range as well as the experimental procedure, including a description of the facility and the data handling and analysis, will be presented.
Under the Kigali Amendment to the Montreal Protocol, new controls are being implemented to reduce emissions of HFC-23 (CHF3), a by-product during the manufacture of HCFC-22 (CHClF2). Starting in 2015, China and India, who dominate global HCFC-22 production (75% in 2017), set out ambitious programs to reduce HFC-23 emissions. Here, we estimate that these measures should have seen global emissions drop by 87% between 2014 and 2017. Instead, atmospheric observations show that emissions have increased and in 2018 were higher than at any point in history (15.9 ± 0.9 Gg yr−1). Given the magnitude of the discrepancy between expected and observation-inferred emissions, it is likely that the reported reductions have not fully materialized or there may be substantial unreported production of HCFC-22, resulting in unaccounted-for HFC-23 by-product emissions. The difference between reported and observation-inferred estimates suggests that an additional ~309 Tg CO2-equivalent emissions were added to the atmosphere between 2015 and 2017.
Recent research has identified significant correlations between traumatic events and depression in refugees. However, few studies have addressed the role of acculturation strategies in this relationship. This study explored the relationship between cultural orientation, traumatic events and depression in female refugees from Syria, Afghanistan, Eritrea, Iran, Iraq, and Somalia living in Germany. We expected acculturation strategies to moderate the effect of traumatic experiences on depression. The sample included 98 female refugees in Germany. The depression scale of the Hopkins Symptom Checklist (HSCL) represented the dependent measure. The trauma checklists derived from the Post-traumatic Diagnostic Scale (PDS) and the Harvard Trauma Questionnaire (HTQ) as well as the Frankfurt Acculturation Scale (FRACC) were used as independent measures for traumatic events and orientation toward the host culture as well as orientation toward the culture of origin, respectively. A moderation analysis was conducted to examine whether the relationship between the number of traumatic events and depression was influenced by the women’s orientation toward the culture of origin and the host culture. We identified a significant model explaining 26.85% of the variance in depressive symptoms (Cohen’s f2 = 0.37). The number of traumatic events and the orientation toward the host culture exerted significant effects on depressive symptoms. The moderating effect was not significant, indicating that the effect of the number of traumatic events was not influenced by cultural orientation. Based on our results, orientation toward the host culture as well as traumatic experiences exert independent effects on depressive symptoms in refugees.
Chronic inflammation is considered to be a cause of the autoimmune diseases such as rheumatoid arthritis, Alzheimer’s disease, multiple sclerosis, etc. The search for effective compounds with anti-inflammatory properties to combat these diseases is still ongoing. Natural compound narciclasine, derived from plants of Narcissus species, demonstrated its anti-inflammatory activity in in vivo arthritis models. Further investigation of narciclasine’s anti-inflammatory activity together with its impact on the interaction between leukocytes and endothelial cells was the main focus of this PhD thesis.
Narciclasine reduced the infiltration of monocytes and neutrophils to the abdomen and the concentration of the pro-inflammatory cytokines TNF, IL-6 and IL-1β. Together with this, it reduced acute visceral pain caused by zymosan injection. Narciclasine interfered with leukocyte-endothelial cell interaction in both in vivo and in vitro models. In vivo microscopy revealed that the compound reduced rolling, adhesion and transmigration of leukocytes in the vessels of an injured murine cremaster muscle. This observation was confirmed in the in vitro models for adhesion and transmigration where narciclasine reduced the level of leukocyte’s interaction with HUVECs. Narciclasine demonstrated profound anti-inflammatory properties based on its interference with leukocyte-endothelium interaction by downregulation of endothelial cell adhesion molecules expression (ICAM-1, VCAM-1, E-selectin, CX3CL1) and shutdown of NF-κB pathway. All these effects were a result of the TNF receptor 1 protein translation blocking by narciclasine.
In this work the ability of the compound to reduce visceral pain, downregulate the expression of the endothelial cell adhesion molecules and to interfere with the interaction between leukocytes and endothelial cells was demonstrated for narciclasine for the first time. Obtained results open a promising insight into the understanding of narciclasine’s anti-inflammatory properties and justify further investigation of its potential for treatment of inflammatory diseases.
In this paper we describe Macrobiotus engbergi sp. nov. and Tenuibiotus zandrae sp. nov. from Greenland. Our study has involved both classical taxonomic methods, which include morphological and morphometric analyses conducted with the use of light and scanning electron microscopy, and genetic analysis based on four molecular markers (three nuclear: 18S rRNA, 28S rRNA, ITS-2, and one mitochondrial: COI). Moreover, we re-examined the type series of Tenuibiotus voronkovi (Tumanov, 2007) as well as the original sample where the species was found and we provide new morphological data from light and scanning electron microscopy which enabled us to amend its description. Finally, we also analysed slides with animals and egg of two populations from Nordaustlandet and Edgeøya (archipelago of Svalbard, Norway) designated as T. voronkovi within its recent redescription. The results and comparisons presented in our study question the validity of this designation.
Objective: Combination antiretroviral therapy (cART) has markedly increased survival and quality of life in people living with HIV. With the advent of new treatment options, including single-tablet regimens, durability and efficacy of first-line cART regimens are evolving.
Methods: We analyzed data from the prospective multicenter German Clinical Surveillance of HIV Disease (ClinSurv) cohort of the Robert-Koch Institute. Kaplan–Meier and Cox proportional hazards models were run to examine the factors associated with treatment modification. Recovery after treatment initiation was analyzed comparing pre-cART viral load and CD4+ T-cell counts with follow-up data.
Results: We included 8788 patients who initiated cART between 2005 and 2017. The sample population was predominantly male (n = 7040; 80.1%), of whom 4470 (63.5%) were reporting sex with men as the transmission risk factor. Overall, 4210 (47.9%) patients modified their first-line cART after a median time of 63 months (IQR 59–66). Regimens containing integrase strand transfer inhibitors (INSTI) were associated with significantly lower rates of treatment modification (adjusted hazard ratio 0.44; 95% CI 0.39–0.50) compared to protease inhibitor (PI)-based regimens. We found a decreased durability of first-line cART significantly associated with being female, a low CD4+ T-cell count, cART initiation in the later period (2011–2017), being on a multi-tablet regimen (MTR).
Conclusions: Drug class and MTRs are significantly associated with treatment modification. INSTI-based regimens showed to be superior compared to PI-based regimens in terms of durability.
The first Oriental species of the genus Trichopsomyia Williston, 1888, Trichopsomyia pilosa sp. nov. (Java), has been discovered and is now described. This Oriental species of Trichopsomyia has several characters strongly differing from the other species within this genus. It is hypothesized that it forms a separate group within Trichopsomyia. One species, Trichopsomyia formiciphila Downes, Skevington & Thompson, 2017, from Australia, is similar to the Oriental species described here, and the group is named after this first described species, hence the formiciphila group. The characters for a future phylogenetic analysis are discussed. The character states of the pilosity of the katepisternum and the shape of the metasternum hitherto used in a phylogenetic analysis of Syrphidae Latreille, 1802 are discussed too.