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We use detailed data on exporters from Costa Rica, Ecuador and Uruguay as well as on their buyers to show that: aggregate exports are disproportionally driven by few multi-buyers exporters; and each multi-buyer exporter's foreign sales of any product are in turn accounted for by few dominant buyers. We propose an analytically solvable multi-country model of endogenous selection in which dominant exporters, dominant products and dominant buyers emerge in parallel as multi-product sellers with heterogeneous technologies compete for buyers with heterogeneous needs. The model not only provides an explanation of the existence of dominant buyers but also makes specific predictions on how the relative importance of dominant buyers should vary across export destinations depending on their market size and accessibility. We show that these predictions are borne out by our data and discuss their welfare implications in terms of gains from trade.
For the transport of high-intensity hadron beams in low-energy beam lines of linear accelerators, the compensation of space charge forces by the accumulation of particles of opposite charge is an important effect, reducing the required focusing strength and potentially the emittance growth due to space charge forces. In this thesis, space charge compensation was studied by including the secondary particles in particle-in-cell simulations.
For this purpose, a new electrostatic particle-in-cell code named bender was developed. The software was tested using known self-consistent solutions for an electron plasma confined in an external potential as well as for a KV distributed beam in a periodic focusing lattice. For the simulation of compensation, models for residual gas ionisation by proton and electron impact were implemented.
The compensation process was studied for a 120 keV, 100 mA proton beam transported through a short drift section. Various features in the particle distributions were identified, which can not explained by a uniform reduction in the electric field of the beam. These were tied to the presence of thermal electrons confined within the beam potential. Using the Poisson-Boltzmann equation, their distribution could be reproduced and their influence on the beam for a wider range of parameters studied. However, the observed temperatures show a significant numerical influence. The hypothesis was formed, that stochastical heating present in particle-in-cell simulations is the mechanism leading to the formation of the observed (partial) thermal equilibrium.
For the low-energy beam transport line of the Frankfurt neutron source FRANZ, bender was used to predict the pulse shaping in the novel ExB chopper system. The code was also used for the design and the study of an electron lens for the Integrable Optics Test Accelerator at Fermi National Accelerator Laboratory. Aberrations due to guiding center drifts and the strong electric field of the electron beam as well as the current limits in such a system were investigated.
This paper explores the impact of immigrants on the imports, exports and productivity of service- producing firms in the U.K. Immigrants may substitute for imported intermediate inputs (offshore production) and they may impact the productivity of the firm as well as its export behavior. The first effect can be understood as the re-assignment of offshore productive tasks to immigrant workers. The second can be seen as a productivity or cost cutting effect due to immigration, and the third as the effect of immigrants on specific bilateral trade costs. We test the predictions of our model using differences in immigrant inflows across U.K. labor markets, instrumented with an enclave-based instrument that distinguishes between aggregate and bilateral immigration, as well as immigrant diversity. We find that immigrants increase overall productivity in service-producing firms, revealing a cost cutting impact on these firms. Immigrants also reduce the extent of country-specific offshoring, consistent with a reallocation of tasks and, finally, they increase country-specific exports, implying an important role in reducing communication and trade costs for services.
In light of increasing division of labour in healthcare, the training and acquisition of both profession-specific and interprofessional competencies have been attributed growing significance, creating the need to test and establish specific teaching formats. Despite ever more complex and interconnected healthcare systems, an increase in patients’ active self-responsibility and innumerable pedagogical and technological innovations, educational systems have not reacted adequately to these new demands. Many authors, not lease the German Council of Science and Humanities, have therefore urged a rethinking of traditional medical education. Student-centred learning activities, such as problem-based and research-based learning, are becoming increasingly significant in view of the numbers of students achieving unsatisfactory levels of competence in critical thinking, communication and writing abilities and complex clinical decision making, for example. The Council of Science and Humanities arrived at a positive evaluation of the various model and reformed courses of study attempting to effectuate a comprehensive reorganisation of medical studies in content and structure as well as methods and didactics. The persistent pervasiveness of instructor-centred learning formats is not only to be found in medical education but in all of the health professions. Although alternative teaching and instruction formats have already been designed and their effectiveness deemed positive in empirical evaluation, the lecture remains the most practised means of transmitting knowledge. In its essence, however, learning is not a question of transmitting information but, moreover, a question of processing information. In traditional instruction units, referred to as “chalk and talk classes” by Becker and Watts, the teaching party presents material in the form of a lecture. As appropriate, questions may be permitted or short processing periods for the students may be integrated into the lecture. The knowledge-assimilating and most essential analysis of the lecture’s contents takes place in the subsequent self-instruction phase, in which the student works alone on concrete tasks. It is during the transfer of knowledge conveyed in the lectures, however, that most questions arise. Of further disadvantage in the traditional lecture is the low level of motivation among students to attend lectures as well as their often heterogeneous knowledge. The Inverted Classroom Model seems to be an eligible instrument for greater facilitation of student-centred and interprofessional learning.
Dieser Artikel beschreibt die Inverted-Classroom-Methode(ICM) im Sinne einer Einführung in die Thematik und soll als Praxisleitleitfaden für diejenigen dienen, die diese Methode in der medizinischen Aus-, Fort- und Weiterbildung einsetzen möchten. Es handelt sich bei der ICM um einen Blended-Learning-Methode, bei dem eine Selbstlernphase (individuelle Phase) vor die Präsenzunterrichtsphase gesetzt wird. In der Online-Phase wird Faktenwissen vermittelt, das als Grundlage für die Präsenzphase dient. Die Präsenzphase soll anschließend dafür genutzt werden, das erlernte Wissen zu vertiefen und anzuwenden. Dem gegenüber stehen die traditionellen Kurskonzepte, in denen das Faktenwissen beispielsweise in Vorlesungen oder in anderen Präsenzunterricht-Formaten vermittelt wird und die Vertiefung dieses Wissens durch die Studierenden im Anschluss daran im Selbststudium stattfinden soll. Das Ziel der ICM ist die Verschiebung des passiven Lernens hin zum aktivierenden Lernen, um das Lernen auf kognitiv anspruchvollen Ebenen wie Analyse, Synthese und Evaluation zu unterstützen. Dabei haben die gestiegene Produktion und Nutzung von Screencasts und Lernvideos, die „Bewegung“ der „Open Educational Resources“ und die verbreitete Nutzung von „Massive Open Online Courses“ (MOOCs) zu einer gestiegenen Verbreitung der Inverted-Classroom-Methode beigetragen. Der Artikel soll als Einführung in die Thematik dienen und dabei eine kurze Übersicht über wichtige Projekte und Forschungsergebnisse in der medizinischen Ausbildung und in weiteren Gesundheitsberufen geben. Außerdem werden die Vor- und Nachteile der Methode und ihr potentieller Nutzen für die zukünftige medizinische Aus- und Weiterbildung dargestellt.
Himaloaesalus gaoligongshanus Huang and Chen, new species (Coleoptera: Lucanidae: Aesalinae) is described from the Gaoligongshan Mts., Yunnan, China. It is the fi fth species of the genus Himaloaesalus Huang and Chen. This new species is similar to the Himalayan species Himaloaesalus himalayicus Kurosawa and H. saburoi Araya et al., from which it is distinguished. The male and female genitalia of all the known species of Himaloaesalus are illustrated. Dorcus yongreni Huang and Chen, new species (Coleoptera: Lucanidae: Lucaninae) is described from Ruili area, Yunnan, China. It belongs to the elegans group (Huang and Chen 2013). This new species is similar to the Indian species Dorcus apatani (Okuda and Maeda), new combination, originally described in Digonophorus Waterhouse. The male genitalia of both species are compared and illustrated.
El género Oogenius Solier, 1851, es revisado y ahora incluye siete especies: O. arrowi Gutiérrez (Argentina), O. castilloi Martínez y Peña (Chile), O. chilensis Ohaus (Chile), O. kuscheli Gutiérrez (Chile), O. lariosae Martínez (Argentina), O. penai Mondaca (Chile), y O. virens Solier (Chile). El género es redescrito, adultos macho y hembra de cada una de las especies son caracterizados, fotografi ados, y los caracteres morfológicos de valor diagnóstico ilustrados. Se incluye una clave de identifi cación, un mapa de distribución e información general sobre la biología de las especies. Basado en el estudio del material tipo, O. chilensis barrosi Gutiérrez, 1949, es considerado un nuevo sinónimo de O. chilensis Ohaus, 1905. Se designan lectotipos para Oogenius chilensis Ohaus, 1905 y Oogenius virens Solier, 1851.
Four species of the genus Enoclerus (Coleoptera: Cleridae) are reported to prey on chemically protected Coccinellidae in North America. The possibility that aposematically colored Enoclerus also mimic prey ladybird species is discussed, and the further possibility that clerid predators acquire chemical protection through sequestration of ladybird prey’s toxic alkaloids is suggested as an important avenue of investigation. The data presented are primarily based on photographs taken by non-specialists, discovered through Internet search. The crowdsourcing of natural history observations can reveal aspects of animal behavior heretofore unreported and even unsuspected.
Two new species of Eburiini (Coleoptera, Cerambycidae, Cerambycinae) are described from Mexico (Guerrero): Susuacanga boteroi; and Eburia (Eburia) girouxae. Both are included in previous keys.
The Republic of Panama currently has 300 recorded species of Trichoptera distributed among 14 families. Herein we add 42 new country records for Panama, including one new family (Anomalopsychidae) and three new genera (Anomalopsychidae: Contulma; Hydroptilidae: Byrsopteryx and Cerasmatrichia). The newly recorded caddisfly taxa increase Panama’s total known fauna to 342 species, distributed among 15 families and 50 genera. These results are part of an ongoing effort to characterize the caddisfly fauna of Panama, and to evaluate that country’s major watersheds (cuencas).
A new species of Neostenoptera (Diptera: Cecidomyiidae: Winnertziinae) from eastern North America
(2016)
A new species of paedogenetic gall midge, Neostenoptera appalachiensis sp. nov., (Diptera: Cecidomyiidae: Winnertziinae: Heteropezini) from the eastern United States is described and illustrated, and pertinent collection and biological data are also provided. It is compared to its congeners, N. kiefferi (Meunier), a subfossil described from African copal, and N. congoensis Gagné, from the Congo. This rare, exciting discovery is the first record of the genus Neostenoptera in the New World.
Parajulid milliped studies XI : Initial assessment of the tribe Gosiulini (Diplopoda: Julida)
(2016)
The parajulid milliped tribe Gosiulini (Diplopoda: Julida) comprises two genera – Gosiulus Chamberlin, with three projections on the posterior gonopod and two species in the southcentral/southwestern United States (US) [Arizona, Colorado, New Mexico, and Texas], and monotypic Minutissimiulus Shelley, n. gen., with two projections, in Nuevo León, Mexico. Gosiulus conformatus Chamberlin occupies the plains/fl atlands of Texas, while its congener inhabits high elevations to the west in all four US states. Both are anticipated in Mexico (Coahuila, Chihuahua, and Sonora), and G. conformatus is expected in southeastern Colorado, eastern New Mexico, and the Oklahoma panhandle. The eastern boundary of G. conformatus and the genus/tribe conforms to the western border of the Piney Woods biome in eastern Texas. As shown by the posterior gonopod drawing in the original description, Parajulus timpius Chamberlin, previously considered of “uncertain generic position or validity,” is unquestionably the oldest name for the western species. The anteriormost posterior gonopod projection, absent from Minutissimiulus, is considered the “prefemoral process,” while the “solenomere” and a third branch arise from a common base.
Because of positional homology with “process ‘C’” in Nesoressini, the last projection is accorded this name, which may also apply to the “prefemoral process” in Aniulini. Minutissimiulus biramus Shelley, n. sp., is proposed along with the following new subjective synonymies: Apacheiulus Loomis under Gosiulus; Ziniulus aethes and Z. medicolens, both by Chamberlin, and Z. ambiguus and Z. nati, both by Loomis, under G. conformatus; and A. pinalensis and A. guadelupensis, both by Loomis, under G. timpius, new combination. Ziniulus navajo Chamberlin becomes an objective synonym of P. timpius because its holotype is designated neotype of the latter. Minutissimiulus biramus Shelley is the fi rst Mexican gosiuline and “mainland” Mexican parajulid not in the tribe Parajulini.
Sandrart.net
(2014)
Sandrart.net describes itself as a ‘research platform for the history of art and culture of the 17th century’. It is a digital edition of Joachim von Sandrart’s magnum opus, the ‘Teutsche Academie’, published between 1675 and 1680 in a German and between 1680 and 1684 in a Latin version. Facsimiles and full texts for both publications are provided as well as a bibliography and additional texts. Browse and search functionalities allow for easy access. Particular emphasis lies on commenting the text and identifying entities such as places, works of art or persons, for which extensive dossiers are provided. These kind of information can also be downloaded as raw XML and as semantic data expressed in RDF. The project undoubtedly marks the state of the art in the critically digitizing and editing 17th century prints.
Es wird davon ausgegangen, dass das ehemalige Larven-Mikrohabitat der Asiatische Tigermücke Aedes albopictus (synonym: Stegomyia albopicta) die Phytotelmata in den Waldgebieten von Südostasien darstellte. In den letzten vier Jahrzehnten adaptierte sich die Art jedoch an urbanere Regionen und ihre Antrotelmata. Dank ihrer Eigenschaft, Eier mit einer gewissen Trocken- und Kältetoleranz zu produzieren, verbreitete sich die Art zusammen mit den international gehandelten Waren weltweit. Zudem ist Ae. albopictus ein theoretischer Vektor für mindestens 27 Viren sowie Parasiten und spielt eine Hauptrolle bei der Übertragung von Dengue-Viren und Chikungunya-Viren und Zika-Vieren. Daher wird die Art als große Gefahr für die öffentliche Gesundheit betrachtet.
Die vorliegende Arbeit thematisiert drei Untersuchungen zum Anpassungs- und Etablierungs-potential der invasiven Asiatischen Tigermücke.
In einem ersten Ansatz wurde das Problem behandelt, dass es lediglich zwei standardisierte toxikologische Testverfahren für Culicidae gab. Daher wurde ein Dosis-Wirkungs-Testsystem entwickelt, das den Weg für weitere biologische Endpunkte und ihre integrativen Parameter freimachte und dadurch ein besseres Verständnis für die Wirkweisen von Insektiziden ermöglicht. Hierdurch konnte nun der Frage nachgegangen werden, ob es Unterschiede in der ökotoxikologischen Reaktion zwischen der invasiven tropisch-subtropischen Asiatischen Tigermücke und der einheimischen nördlichen Hausstechmücke Culex pipiens auf das Insektizid λ-Cyhalothrin gibt. Weiter wurde der Einfluss von Temperatur und die Verfügbarkeit von Nahrung auf die Insektizidsensitivitäten der Arten getestet. Schließlich konnte in einer Risikobewertung festgestellt werden, dass bei falsch angewendeten Bekämpfungsmaßnahmen höhere Temperaturen sowie der Ausfall von aquatischen Top-Prädatoren zu Fitnessvorteilen für die Art führen können.
In einer zweiten Untersuchung wurde der Mechanismus der Kältetoleranz der Eier (Kälteakklimatisierung und Diapause) näher untersucht, da dieser für die erfolgreiche Invasion in gemäßigten Breitengraden verantwortlich gemacht wird. Nachdem eine lang vorherrschende Hypothese verworfen wurde, dass die Einlagerung von Polyolen die Frosttoleranz bewirken würde, war der aktuelle Stand der Wissenschaft, dass eine Verdickung der Wachsschicht des Chorions dafür verantwortlich sei. Jedoch lag keine detaillierte Evaluierung von Stechmücken-Eihüllen vor. Mittels einer transmissionselektronenmikroskopischen Studie konnte gezeigt werden, dass nicht nur die Wachsschicht nicht in der Serosa-Cuticula zu verorten ist, sondern im Endochorion und sie zudem im Zuge der Diapause in der Mächtigkeit schrumpft. Daher wird auf Basis der gewonnenen Erkenntnisse auf eine Kompaktierung der Schicht geschlossen.
Die dritte Untersuchung schließlich hatte das hohe Adaptationspotential in gemäßigten Breiten zum Gegenstand. Eine Adaptation auf genetischen Level gilt als unwahrscheinlich, da Gründerpopulationen in den neu besiedelten Gebieten eine niedrige genetische Diversität aufwiesen und ein regelmäßiger Neueintrag von Allelen unwahrscheinlich ist. Jedoch bietet das Konzept der epigenetischen Temperatur-Adaptation einen Erklärungsansatz für dieses Phänomen. Daher wurde die Frage gestellt, ob es möglich ist, eine vererbbare Diversifizierung dieses kältetoleranten Phänotyps nach einer randomisierten epigenetischen Behandlung der DNA zu detektieren. Es wurde eine transgenerationale Untersuchung der Effekte von zwei epigenetischen Agenzien (und einem Lösemittel) auf die Kältetoleranz der Eier durchgeführt. Die Ergebnisse zeigten ein Korrelationsmuster, das den durch die Agenzien veränderten Methylierungsgrad der DNA mit der Forsttoleranz verband, was die gestellte Hypothese unterstützte.
In Folge dieser drei Untersuchungen wurde festgestellt, dass Ae. albopictus ein hohes Potential hat, in weiteren Ländern – vor allem in gemäßigten Breiten – ein Gesundheitsrisiko darzustellen. Da die Art einerseits Fitnessvorteile durch falsche Bekämpfungsmaßnahmen und andererseits möglicherweise eine hohes epigenetisches Adaptationspotential besitzt, kann zusammenfassend empfohlen werden, dass der Fokus für weitere Forschung maßgeblich auf der Entwicklung von Impfstoffen für die übertragenen Viren und Pathogene liegen sollte. Dadurch kann die Bevölkerung geschützt werden, ohne Ökosysteme und ihre Dienstleistungen zu gefährden, und dies wäre zudem ökonomisch gesehen die effektivere Lösung.