Thermodynamics of Thermoelectric Phenomena and Applications

Fifty years ago, the optimization of thermoelectric devices was analyzed by considering the relation between optimal performances and local entropy production. Entropy is produced by the irreversible processes in thermoelectric devices. If these processes could be eliminated, entropy production would be reduced to zero, and the limiting Carnot efficiency or coefficient of performance would be obtained. In the present review, we start with some fundamental thermodynamic considerations relevant for thermoelectrics. Based on a historical overview, we reconsider the interrelation between optimal performances and local entropy production by using the compatibility approach together with the thermodynamic arguments. Using the relative current density and the thermoelectric potential, we show that minimum entropy production can be obtained when the thermoelectric potential is a specific, optimal value

Establishment of pluripotent cell lines from vertebrate species - Present status and future prospects

Pluripotent embryonic stem (ES) cells are undifferentiated cell lines derived from early embryos and are capable of unlimited undifferentiated proliferation in vitro. They retain the ability to differentiate into all cell types including germ cells in chimeric animals in vivo, and can be induced to form derivatives of all three germ layers in vitro. Mouse ES cells represent one of the most important tools in genetic research. Major applications include the targeted mutation of specific genes by homologous recombination and the discovery of new genes by gene trap strategies. These applications would be of high interest for other model organisms and also for livestock species, However, in spite of tremendous research activities, no proven ES cells colonizing the germ line have been established for vertebrate species other than mouse a nd chicken thus far. This review summarizes the current status of deriving pluripotent embryonic stem cell lines from vertebrates and recent developments in nuclear transfer technology, which may provide an alternative tool for genetic modification of livestock animals. Copyright (C) 1999 S. Karger AG, Basel

Periderm invasion contributes to epithelial formation in the teleost pharynx

The gnathostome pharyngeal cavity functions in food transport and respiration. In amniotes the mouth and nares are the only channels allowing direct contact between internal and external epithelia. In teleost fish, gill slits arise through opening of endodermal pouches and connect the pharynx to the exterior. Using transgenic zebrafish lines, cell tracing, live imaging and different markers, we investigated if pharyngeal openings enable epithelial invasion and how this modifies the pharyngeal epithelium. We conclude that in zebrafish the pharyngeal endoderm becomes overlain by cells with a peridermal phenotype. In a wave starting from pouch 2, peridermal cells from the outer skin layer invade the successive pouches until halfway their depth. Here the peridermal cells connect to a population of cells inside the pharyngeal cavity that express periderm markers, yet do not invade from outside. The latter population expands along the midline from anterior to posterior until the esophagus-gut boundary. Together, our results show a novel role for the periderm as an internal epithelium becomes adapted to function as an external surface.Agência financiadora Ghent University Research Fund - BOF24J2015001401 Cancer Prevention Research Institute of Texas - RR140077info:eu-repo/semantics/publishedVersio

Analysis of a short tail type in farmed Atlantic salmon (Salmo salar)

The short tail phenotype represents one of the main causes for downgrading of farmed Atlantic salmon (Salmo salar) at slaughterhouses. Prevalence of short tail is variable and the aetiology is suspected to be multi-factorial. Risk factors have been identified but descriptions of the aetiology and the pathology of the condition are still rare. In the current study, a radiological and histological analysis of short tails has been performed, examining six normal and six downgraded individuals from a slaughterhouse in southern Norway. In the short tail phenotype, vertebral bodies were shifted and bent at the contact zone of adjacent vertebral bodies. Changes either affected the entire spine or were located at the medial caudal-spine. While the internal bone structure of the vertebrae was similar in deformed and non-deformed animals, a lack of intervertebral space apparently caused a shortening of the vertebral column and corresponded to an elevated condition factor in deformed individuals. Histological analysis revealed different degrees of proliferation of cartilaginous tissues, which replaced the intervertebral notochord tissue. The displacement of adjacent vertebral bodies and the development of cartilage in between vertebral bodies suggest mechanical forces as a possible cause for the observed deformations, since mechanically-induced overload and a subsequent direct contact of bones are factors that can stimulate heterotopic cartilage development and pseudoarthrosi

Light microscopic studies on the development of Beauveria bassiana and other putative endophytes in leaf tissues

Die vorliegende Untersuchung beinhaltete sechs Testpilze, über die in der Literatur Berichte als Endophyten vorliegen (Beauveria bassiana, Metarhizium anisopliae, Isaria fumosorosea, Trichoderma harzianum, Fusarium proliferatum, Chaetomium globosum), zwei phytopathogene Pilze (Ascochyta fabae, Plenodomus lingam) und vier Wirtspflanzen (Vicia faba, Brassica napus, Phaseolus vulgaris, Zea mays). Die Konidien oder Blastosporen bzw. Ascosporen der Testpilze wurden durch Sprühen auf die Blatt­ober­fläche oder durch Infiltration durch die Spaltöffnungen appliziert. Die lichtmikroskopische Untersuchung zeigte, dass die Sporen auf der Blattoberfläche auskeimten, aber nicht aktiv in die Blätter eindrangen. Im Blatt­inneren schienen Sporenkeimung und Hyphenwachstum auf Bereiche mit Zell- bzw. Gewebeschädigung beschränkt zu sein. Verschiedene Wirtsreaktionen wurden beobachtet, wie die Verbräunung von Epidermiszellen und die Bildung von Papillen. Eine Besiedlung des Gewebes vergleichbar der mit den Pathogenen A. fabae (bei Ackerbohne) und P. lingam (bei Raps) wurde nicht beobachtet. Erst nach Auslegen von inokuliertem Blattmaterial auf Agarmedium setzten Sporenkeimung und Hyphenwachstum im Blattinneren ein. Die Ergebnisse deuten eher auf eine saprotrophe als auf eine endophytische Lebensweise der untersuchten Pilze im Blattgewebe der untersuchten Wirtspflanzen hin.The study involved six test fungi previously recorded in the literature as being endophytes (Beauveria bassiana, Metarhizium anisopliae, Isaria fumosorosea, Trichoderma harzianum, Fusarium proliferatum, Chaetomium globosum), two plant pathogenic fungi (Ascochyta fabae, Plenodomus lingam) and four host plants (Vicia faba, Bras­sica napus, Phaseolus vulgaris, Zea mays). Aerial conidia, blastospores, or ascospores, respectively were applied to leaf surfaces by spraying or by infiltrating spore suspensions through stomata directly into the leaves. Obser­vations using light microscopy showed that the test fungi germinated on the leaf surface but did not enter actively into the leaves. Within the leaves, germination of spores and growth of hyphae appeared to depend on the presence of damaged plant tissue. Various host reactions such as browning of epidermal cells and formation of papillae were observed. Colonization of healthy leaves by the test fungi in a manner similar to the pathogens A. fabae (on Faba bean) and P. lingam (on oilseed rape) was not observed. Spore germination and hyphal growth commenced when inoculated leaves were placed on agar medium. The results indicate that the test fungi possessed a saprotrophic rather than an endo­phytic life style when associated with leaf tissue of the studied hosts

Biology of the black rot pathogen, Guignardia bidwellii, its development in susceptible leaves of grapevine Vitis vinifera

Seit 2002 / 2003 tritt die durch den Ascomyceten Guignardia bidwellii hervorgerufene Schwarzfäule regelmäßig in ökologisch bewirtschafteten Weinbergen an Mosel, Nahe und im Mittelrheintal auf. Obwohl die Krankheit, ursprünglich aus den USA kommend, schon seit über 100 Jahren in Südeuropa bekannt ist, ist das Wissen über die Biologie von G. bidwellii noch immer lückenhaft. In der vorliegenden Arbeit wird der Lebenszyklus von G. bidwellii mit histologisch-mikroskopischen Methoden (Durchlicht-, Fluoreszenz- und Elektronenmikroskopie) untersucht. Die Entwicklung des Pilzes in einer anfälligen Rebsorte (Riesling) wird von der Sporenkeimung bis zur Ausbildung der Pyknidien und Pseudothezien verfolgt. Der Schwerpunkt der Arbeit liegt auf der Entwicklung nach dem Eindringen in den Wirt, die durch subcuticuläres Wachstum charakterisiert ist. Ziel ist die Verbreiterung der Wissensbasis über die Biologie von G. bidwelli sowie die Erarbeitung einer Grundlage für die Entwicklung effizienter Bekämpfungsmethoden und eine histologische Charakterisierung der Sortenresistenz.Since 2002 / 2003 black rot caused by Guignardia bidwellii is regularly occurring in organic viticulture in the wine growing areas at the Mosel and Nahe River and in the Middle Rhine valley in Germany. Though the disease originates from the USA and is known in Europe already for more than 100 years, the knowledge about the biology of its causal organism is still scanty. In the present study the life cycle of G. bidwellii is analysed with histological microscopical methods (bright field, phase contrast, fluorescence and electron microscopy). The development of the fungus on a susceptible grapevine variety (Riesling) is followed from spore germination up to the development of pycnidia and pseudothecia. The study is focused on the phase after penetration of the fungus which is characterized by subcuticular spread. The aim is to broaden the knowledge of the biology of G. bidwellii, to provide the basis for efficient control measures and to enable the histological characterization of varietal resistance

The VISTA Science Archive

We describe the VISTA Science Archive (VSA) and its first public release of data from five of the six VISTA Public Surveys. The VSA exists to support the VISTA Surveys through their lifecycle: the VISTA Public Survey consortia can use it during their quality control assessment of survey data products before submission to the ESO Science Archive Facility (ESO SAF); it supports their exploitation of survey data prior to its publication through the ESO SAF; and, subsequently, it provides the wider community with survey science exploitation tools that complement the data product repository functionality of the ESO SAF. This paper has been written in conjunction with the first public release of public survey data through the VSA and is designed to help its users understand the data products available and how the functionality of the VSA supports their varied science goals. We describe the design of the database and outline the database-driven curation processes that take data from nightly pipeline-processed and calibrated FITS files to create science-ready survey datasets. Much of this design, and the codebase implementing it, derives from our earlier WFCAM Science Archive (WSA), so this paper concentrates on the VISTA-specific aspects and on improvements made to the system in the light of experience gained in operating the WSA.Comment: 22 pages, 16 figures. Minor edits to fonts and typos after sub-editting. Published in A&