6,622 research outputs found
Mid-Infrared line diagnostics of Active Galaxies -- A spectroscopic AGN survey with ISO-SWS
We present medium resolution (R approx. 1500) ISO-SWS 2.4--45 micron spectra
of a sample of 29 galaxies with active nuclei. This data set is rich in fine
structure emission lines tracing the narrow line regions and (circum-)nuclear
star formation regions, and it provides a coherent spectroscopic reference for
future extragalactic studies in the mid-infrared. We use the data set to
briefly discuss the physical conditions in the narrow line regions (density,
temperature, excitation, line profiles) and to test for possible differences
between AGN sub-types. Our main focus is on new tools for determining the
propertibes of dusty galaxies and on the AGN-starburst connection. We present
mid-IR line ratio diagrams which can be used to identify composite (starburst +
AGN) sources and to distinguish between emission excited by active nuclei and
emission from (circum-nuclear) star forming regions. For instance, line ratios
of high to low excitation lines like [O IV]25.9um/[Ne II]12.8um, that have been
used to probe for AGNs in dusty objects, can be examined in more detail and
with better statistics now. In addition, we present two-dimensional diagnostic
diagrams that are fully analogous to classical optical diagnostic diagrams, but
better suited for objects with high extinction. Finally, we discuss
correlations of mid-infrared line fluxes to the mid- and far-infrared
continuum. We compare these relations to similar relations in starburst
galaxies in order to examine the contribution of AGNs to the bolometric
luminosities of their host galaxies. The spectra are available in electronic
form from the authors.Comment: 24 pages, 23 figures, 5 tables. Accepted for A&
Issues in the Design of a Pilot Concept-Based Query Interface for the Neuroinformatics Information Framework
This paper describes a pilot query interface that has been constructed to help us explore a "concept-based" approach for searching the
Neuroscience Information Framework (NIF). The query interface is
concept-based in the sense that the search terms submitted through the
interface are selected from a standardized vocabulary of terms
(concepts) that are structured in the form of an ontology. The NIF
contains three primary resources: the NIF Resource Registry, the NIF
Document Archive, and the NIF Database Mediator. These NIF resources
are very different in their nature and therefore pose challenges when
designing a single interface from which searches can be automatically
launched against all three resources simultaneously. The paper first
discusses briefly several background issues involving the use of
standardized biomedical vocabularies in biomedical information
retrieval, and then presents a detailed example that illustrates how
the pilot concept-based query interface operates. The paper concludes
by discussing certain lessons learned in the development of the current
version of the interface
«Prozessintelligenz» : Gegenstand und Ziele der Studie
«Intelligente Prozesse, «intelligentes Prozessmanagement», «iBPM» sind Schlagworte, die in erster Linie eingesetzt werden, um Technologien zu vermarkten. Die Begriffe lassen viel Raum fĂŒr Interpretation und Assoziationen. Können Unternehmen den Hype ignorieren oder bietet «Prozessintelligenz» die Chance, das Prozessmanagement aus einem anderen Blickwinkel zu betrachten und weiterzuentwickeln? Doch was ist Prozessintelligenz? Welche LösungsansĂ€tze, Erfahrungen und Erfolgsmuster gibt es bereits in Unternehmen? Welche Methoden und Werkzeuge kommen zum Einsatz, um Prozesse «intelligenter» zu machen? Diesen Fragen hat sich die Business-Process-Management-Studie 2015 gestellt, mit der das Institut fĂŒr Wirtschaftsinformatik der ZĂŒrcher Hochschule fĂŒr Angewandte Wissenschaften School of Management and Law seit 2011 regelmĂ€ssig Status quo und Best Practices im deutschsprachigen Raum erhebt
Central Nervous System Parasitosis and Neuroinflammation Ameliorated by Systemic IL-10 Administration in Trypanosoma brucei-Infected Mice
Peer reviewedPublisher PD
Malaria transmission potential could be reduced with current and future climate change
Several studies suggest the potential for climate change to increase malaria incidence in cooler, marginal transmission environments. However, the effect of increasing temperature in warmer regions where conditions currently support endemic transmission has received less attention. We investigate how increases in temperature from optimal conditions (27â°C to 30â°C and 33â°C) interact with realistic diurnal temperature ranges (DTR:â±â0â°C, 3â°C, and 4.5â°C) to affect the ability of key vector species from Africa and Asia (Anopheles gambiae and An. stephensi) to transmit the human malaria parasite, Plasmodium falciparum. The effects of increasing temperature and DTR on parasite prevalence, parasite intensity, and mosquito mortality decreased overall vectorial capacity for both mosquito species. Increases of 3â°C from 27â°C reduced vectorial capacity by 51-89% depending on species and DTR, with increases in DTR alone potentially halving transmission. At 33â°C, transmission potential was further reduced for An. stephensi and blocked completely in An. gambiae. These results suggest that small shifts in temperature could play a substantial role in malaria transmission dynamics, yet few empirical or modeling studies consider such effects. They further suggest that rather than increase risk, current and future warming could reduce transmission potential in existing high transmission settings
[The Impact of Nuclear Star Formation on Gas Inflow to AGN
Our adaptive optics observations of nearby AGN at spatial resolutions as
small as 0.085arcsec show strong evidence for recent, but no longer active,
nuclear star formation. We begin by describing observations that highlight two
contrasting methods by which gas can flow into the central tens of parsecs. Gas
accumulation in this region will inevitably lead to a starburst, and we discuss
the evidence for such events. We then turn to the impact of stellar evolution
on the further inflow of gas by combining a phenomenological approach with
analytical modelling and hydrodynamic simulations. These complementary
perspectives paint a picture in which all the processes are ultimately
regulated by the mass accretion rate into the central hundred parsecs, and the
ensuing starburst that occurs there. The resulting supernovae delay accretion
by generating a starburst wind, which leaves behind a clumpy interstellar
medium. This provides an ideal environment for slower stellar outflows to
accrete inwards and form a dense turbulent disk on scales of a few parsecs.
Such a scenario may resolve the discrepancy between the larger scale structure
seen with adaptive optics and the small scale structure seen with VLTI.Comment: to appear in: Co-Evolution of Central Black Holes and Galaxies; 7
page
Spatially and genetically distinct African trypanosome virulence variants defined by host interferon-g response
We describe 2 spatially distinct foci of human African trypansomiasis in eastern Uganda. The Tororo and Soroti foci of <i>Trypanosoma brucei rhodesiense</i> infection were genetically distinct as characterized by 6 microsatellite and 1 minisatellite polymorphic markers and were characterized by differences in disease progression and host-immune response. In particular, infections with the Tororo genotype exhibited an increased frequency of progression to and severity of the meningoencephalitic stage and higher plasma interferon (IFN)âÎł concentration, compared with those with the Soroti genotype. We propose that the magnitude of the systemic IFN-Îł response determines the time at which infected individuals develop central nervous system infection and that this is consistent with the recently described role of IFN-Îł in facilitating blood-brain barrier transmigration of trypanosomes in an experimental model of infection. The identification of trypanosome isolates with differing disease progression phenotypes provides the first field-based genetic evidence for virulence variants in T. <i>brucei rhodesiense</i>
Direct scheme for measuring the geometric quantum discord
We propose a scheme to directly measure the exact value of geometric quantum
discord of an arbitrary two-qubit state. We only need to perform the projective
measurement in the all anti-symmetric subspace and our scheme is parametrically
efficient in contrast to the widely adopted quantum state tomography scheme in
the sense of less parameter estimations and projectors. Moreover, the present
scheme can be easily realized with the current experimental techniques.Comment: 9 pages,1 figure, submitted to J. Phys. A: Math. Theo
PTF11kx: A Type-Ia Supernova with a Symbiotic Nova Progenitor
There is a consensus that Type-Ia supernovae (SNe Ia) arise from the
thermonuclear explosion of white dwarf stars that accrete matter from a binary
companion. However, direct observation of SN Ia progenitors is lacking, and the
precise nature of the binary companion remains uncertain. A temporal series of
high-resolution optical spectra of the SN Ia PTF 11kx reveals a complex
circumstellar environment that provides an unprecedentedly detailed view of the
progenitor system. Multiple shells of circumsteller are detected and the SN
ejecta are seen to interact with circumstellar material (CSM) starting 59 days
after the explosion. These features are best described by a symbiotic nova
progenitor, similar to RS Ophiuchi.Comment: 27 pages, 5 figures. In pres
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