678 research outputs found
Asymptotic eigenfunctions for Schrödinger operators on a vector bundle
In the limit , we analyze a class of Schr\"odinger operators acting on sections of a vector bundle over a Riemannian manifold where is a Laplace type operator, is an endomorphism field and the potential energy has a non-degenerate minimum at some point . We construct quasimodes of WKB-type near for eigenfunctions associated with the low lying eigenvalues of . These are obtained from eigenfunctions of the associated harmonic oscillator at , acting on smooth functions on the tangent space
Warum rauchen Schizophreniepatienten?
Zusammenfassung: Patienten mit schizophrenen Störungen zeigen eine erhöhte PrĂ€valenz der NikotinabhĂ€ngigkeit. Diese Arbeit beleuchtet die ZusammenhĂ€nge zwischen Schizophrenie und Nikotinkonsum. Es gibt deutliche Hinweise dafĂŒr, dass wesentliche Bereiche kognitiver Funktionen bei Patienten mit schizophrenen Erkrankungen durch Nikotin verbessert werden, insbesondere Daueraufmerksamkeit, gerichtete Aufmerksamkeit, ArbeitsgedĂ€chtnis, KurzzeitgedĂ€chtnis und Wiedergabe aus dem GedĂ€chtnis. Auch konnten in einigen Studien mittels ereigniskorrelierten Potenzialen (P50-Paradigma) und der PrĂ€pulsinhibition des akustisch ausgelösten Schreckreflexes gezeigt werden, dass prĂ€attentive MaĂe der Informationsverarbeitung, die eine zentrale Rolle in der Schizophrenie spielen, durch Gabe von Nikotin verbessert werden können. Weiterhin kann Rauchen die durch antipsychotische Medikamente hervorgerufenen extrapyramidalen Nebenwirkungen verbessern, und es induziert das Zytochrom P4501A2, das auch an der Metabolisierung einiger Neuroleptika beteiligt ist. Zusammenfassend kann festgestellt werden, dass die Nikotinzufuhr bei Patienten mit schizophrenen Störungen eine Form der "Selbstmedikation" darstellen könnte, um Defizite im Bereich Aufmerksamkeit, Kognition und Informationsverarbeitung zu verbessern und um Nebenwirkungen von Antipsychotika zu reduzieren. Mögliche pharmakotherapeutische AnsĂ€tze zur Behandlung der gestörten Neurotransmission am nikotinergen Azetylcholinrezeptor werden diskutier
Design and construction of 2 transonic airfoil models for tests in the NASA Langley C.3-M TCT
As part of a NASA/DFVLR cooperation program two transonic airfoils were tested in the NASA Langley 0.3-m TCT. Model design and construction was carried out by DFVLR. The models designed and constructed performed extremely well under cryogenic conditions. Essentially no permanent changes in surface quality and geometric dimensions occurred during the tests. The aerodynamic results from the TCT tests which demonstrate the large sensitivity of the airfoil CAST 10-Z/DOAZ to Reynolds number changes compared well with results from other facilities at ambient temperatures
The Relationship between Brachycephalic Head Features in Modern Persian Cats and Dysmorphologies of the Skull and Internal Hydrocephalus
Background: Cat breeders observed a frequent occurrence of internal hydrocephalus in Persian cats with extreme brachycephalic head morphology. Objective: To investigate a possible relationship among the grade of brachycephaly, ventricular dilatation, and skull dysmorphologies in Persian cats. Animals: 92 Persian-, 10 Domestic shorthair cats. Methods: The grade of brachycephaly was determined on skull models based on CT datasets. Cranial measurements were examined with regard to a possible correlation with relative ventricular volume, and cranial capacity. Persians with high (peke-face Persians) and lower grades of brachycephaly (doll-face Persians) were investigated for the presence of skull dysmorphologies.
Results: The mean cranial index of the peke-face Persians (0.97 ± 0.14) was significantly higher than the mean cranial index of doll-face Persians (0.66 ± 0.04; P < 0.001). Peke-face Persians had a lower relative nasal bone length (0.15 ± 0.04) compared to doll-face (0.29 ± 0.08; P < 0.001). The endocranial volume was significantly lower in doll-face than peke-face Persians (89.6 ± 1.27% versus 91.76 ± 2.07%; P < 0.001). The cranial index was significantly correlated with this variable (SpearmanŽs r: 0.7; P < 0.0001).
Mean ventricle: Brain ratio of the peke-face group (0.159 ± 0.14) was significantly higher compared to doll-face Persians (0.015 ± 0.01; P < 0.001). Conclusion and Clinical Relevance: High grades of brachycephaly are also associated with malformations of the calvarial and facial bones as well as dental malformations. As these dysmorphologies can affect animal welfare, the selection for extreme forms of brachycephaly in Persian cats should be reconsidered
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Neutronic data in support of space nuclear propulsion
The thermophysical properties of lithium hydride ({sup 7}LiH), particularly small density (0.775 gm/cc), high melting point (688 C) and relatively high hydrogen atomic number density makes it an attractive material for use as a neutron moderator and shield (for LiH) in space nuclear thermal propulsion. However, the unavailability of neutronic cross section data in the thermal energy range for {sup 7}LiH in the ENDF/B library necessitated the generation of the relevant data which is required in criticality studies and for the determination of temperature-dependent feedback coefficients in the moderator and fuel regions. Here, the scattering kernel data for {sup 7}LiH have been generated for the first time in the temperature range 50--1,000 K. This is based on a phonon distribution function derived from both experimental data and theoretical calculations. A detailed study of the variation of the moderator temperature coefficient {alpha}{sub m}(T) with temperature, T, is carried out for a typical space nuclear reactor of the particle bed type. It is established that the moderator temperature coefficient is proportional to T{sup {minus}1.65} where T is the moderator temperature in Kelvin units
MHC class II-restricted antigen presentation by plasmacytoid dendritic cells drives proatherogenic T cell immunity
BackgroundâPlasmacytoid dendritic cells (pDCs) bridge innate and adaptive immune responses and are important regulators of immuno-inflammatory diseases. However, their role in atherosclerosis remains elusive.
Methods and ResultsâHere, we used genetic approaches to investigate the role of pDCs in atherosclerosis. Selective pDC deficiency in vivo was achieved using CD11c-Cre Ă Tcf4â/flox bone marrow transplanted into Ldlrâ/â mice. Compared with control Ldlrâ/â chimeric mice, CD11c-Cre Ă Tcf4â/flox mice had reduced atherosclerosis levels. To begin to understand the mechanisms by which pDCs regulate atherosclerosis, we studied chimeric Ldlrâ/â mice with selective MHCII deficiency on pDCs. Significantly, these mice also developed reduced atherosclerosis compared with controls without reductions in pDC numbers or changes in conventional DCs. MHCII-deficient pDCs showed defective stimulation of apolipoprotein B100âspecific CD4+ T cells in response to native low-density lipoprotein, whereas production of interferon-α was not affected. Finally, the atheroprotective effect of selective MHCII deficiency in pDCs was associated with significant reductions of proatherogenic T cellâderived interferon-Îł and lesional T cell infiltration, and was abrogated in CD4+ T cellâdepleted animals.
ConclusionsâThis study supports a proatherogenic role for pDCs in murine atherosclerosis and identifies a critical role for MHCII-restricted antigen presentation by pDCs in driving proatherogenic T cell immunity
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Collimator design for the NSNS accumulator ring
Collimators are used to remove halo or off-momentum particles from the main proton beam. Off-momentum particles are removed by situating collimators in high dispersion areas of the beam. In addition to removing halo particles collimators will also act as shielding for the remainder of the accelerator structures. Thus, collimators reduce uncontrolled losses around the ring and reduce activation of the accelerator components. Requirements and performance goals for the collimator are summarized. In order to meet these goals a self-shielding collimator configuration will be designed. An arrangement consisting of a layered structure will be considered. The initial layers (in the direction of the proton beam) are transparent to protons, and become progressively less transparent (blacker) with depth into the collimator. In addition, a high density (iron) shield will be added around this structure, particularly in the backward direction, to attenuate any reflected protons. The protons are stopped in the approximate center of the collimator, and thus the bulk of the secondary particles will also be generated there. Since these secondary particles are primarily produced isotropically their leakage path length will be maximized in this manner (high probability of capture or attenuation). In the case of neutrons a black layer is included at each end in order to further minimize their leakage in the direction of the beam. This design will therefore minimize the activation of surrounding accelerator components
Indikatoren einer tiergerechten Mastputenhaltung unter den Bedingungen der ökologischen GeflĂŒgelmast
Ziel der Studie war eine Analyse der HĂ€ufigkeit und des AusprĂ€gungsgrades tierschutzrelevanter VerĂ€nderungen bei Puten, die gemÀà den Bedingungen der EU-Verordnung 889/2008 fĂŒr den ökologischen Landbau gehalten wurden. In zwei DurchgĂ€ngen wurden in neun Aufzucht- und 14 Mastbetrieben 32 Herden mit insgesamt 105.483 Tieren erfasst. Der Tiergesundheitsstatus der einzelnen Herden wurde stichprobenartig an fĂŒnf Zeitpunkten durch Beurteilung von 60 Einzeltieren dokumentiert. Bei jedem Bestandsbesuch wurden auĂerdem Einstreuproben entnommen und ihr Feuchtigkeitsgehalt thermogravimetrisch bestimmt.
Die mittlere kumulierte Verlustrate in der Aufzuchtphase lag bei 3,3 % und in der 16. Lebenswoche bei 4,5%. Am Ende der Aufzuchtphase wiesen bis zu 44 % der untersuchten Tiere Epithelnekrosen an den FuĂballen auf. HĂ€ufigkeit und Schweregrad von BallenverĂ€nderungen nahmen im Verlauf der Mastphase weiter zu. So wurden in der 16. Lebenswoche bei ĂŒber 80 % der untersuchten Puten Ballennekrosen festgestellt.
Am Schlachthof erfolgte eine Aufnahme allgemeiner Daten zur Schlachtung und folgend die visuelle Beschau von 60 Puten je Herde. Der ĂŒberwiegende Teil der Tiere (97,7%) wies zum Zeitpunkt der Schlachtung VerĂ€nderungen der FuĂballen auf, wĂ€hrend BrusthautverĂ€nderungen nur selten dokumentiert wurden. Vermehrt traten weiterhin LeberverĂ€nderungen, insbesondere GrĂŒnfĂ€rbungen auf, wobei deutliche Unterschiede zwischen verschiedenen Betrieben sowie zwischen den einzelnen DurchgĂ€ngen festgestellt wurden. Auch GelenksverĂ€nderungen waren hĂ€ufige Befunde.
Als ein maĂgeblicher Faktor fĂŒr die Gesunderhaltung eines Putenbestandes ist die BefĂ€higung des bestandsbetreuenden Personenkreises anzusehen, gesundheitliche Probleme frĂŒhzeitig zu erkennen und zeitnah darauf zu reagieren. Neben der QualitĂ€t des Einstreusubstrates inklusive Beurteilung der Kotkonsistenz können HĂ€ufigkeit und AusprĂ€gung von BallenverĂ€nderungen wertvolle Hinweise fĂŒr eine EinschĂ€tzung des Tierhaltungsstandards in einem Bestand liefern und sind als wichtige, einfach erfassbare Tierschutzindikatoren einzustufen . Auch Gelenks- und LeberverĂ€nderungen sind aufgrund hoher PrĂ€valenzen als relevante Tiergesundheitsparameter zu betrachten, die im Rahmen eines Monitorings routinemĂ€Ăig erfasst werden sollten
Coincidence of paroxysmal supraventricular tachycardia and panic disorder: two case reports
Panic disorder (PD) is characterised by sudden attacks of intense fear with somatic symptoms including palpitations and tachycardia. Reciprocally, palpitations caused by paroxysmal supraventricular tachycardia (PSVT) are commonly associated with anxiety and may therefore be misdiagnosed as PD. As demonstrated by two case reports, PSVT and PD can occur comorbidly in a chronological sequence, with PSVT possibly precipitating and maintaining PD via interoceptive processes or, alternatively, with PD increasing the risk for PSVT by elevating stress levels. As both PSVT and PD require different treatments, potentially helpful differential clinical diagnostic criteria are proposed
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