997 research outputs found
Social structures depend on innate determinants and chemosensory processing in Drosophila
Flies display transient social interactions in groups. However, whether flyâfly interactions are stochastic or structured remains unknown. We hypothesized that groups of flies exhibit patterns of social dynamics that would manifest as nonrandom social interaction networks. To test this, we applied a machine vision system to track the position and orientation of flies in an arena and designed a classifier to detect interactions between pairs of flies. We show that the vinegar fly, Drosophila melanogaster, forms nonrandom social interaction networks, distinct from virtual network controls (constructed from the intersections of individual locomotor trajectories). In addition, the formation of interaction networks depends on chemosensory cues. Gustatory mutants form networks that cannot be distinguished from their virtual network controls. Olfactory mutants form networks that are greatly disrupted compared with control flies. Different wild-type strains form social interaction networks with quantitatively different properties, suggesting that the genes that influence this network phenotype vary across and within wild-type populations. We have established a paradigm for studying social behaviors at a group level in Drosophila and expect that a genetic dissection of this phenomenon will identify conserved molecular mechanisms of social organization in other species
Social structures depend on innate determinants and chemosensory processing in Drosophila
Flies display transient social interactions in groups. However, whether flyâfly interactions are stochastic or structured remains unknown. We hypothesized that groups of flies exhibit patterns of social dynamics that would manifest as nonrandom social interaction networks. To test this, we applied a machine vision system to track the position and orientation of flies in an arena and designed a classifier to detect interactions between pairs of flies. We show that the vinegar fly, Drosophila melanogaster, forms nonrandom social interaction networks, distinct from virtual network controls (constructed from the intersections of individual locomotor trajectories). In addition, the formation of interaction networks depends on chemosensory cues. Gustatory mutants form networks that cannot be distinguished from their virtual network controls. Olfactory mutants form networks that are greatly disrupted compared with control flies. Different wild-type strains form social interaction networks with quantitatively different properties, suggesting that the genes that influence this network phenotype vary across and within wild-type populations. We have established a paradigm for studying social behaviors at a group level in Drosophila and expect that a genetic dissection of this phenomenon will identify conserved molecular mechanisms of social organization in other species
Concurrent Outbreak of Norovirus Genotype I and Enterotoxigenic Escherichia coli on a U.S. Navy Ship following a Visit to Lima, Peru
An outbreak of norovirus (NoV) genotype I and Enterotoxigenic Escherichia coli (ETEC) occurred among US Navy Ship personnel following a visit to Lima, Peru, in June 2008. Visiting a specific area in Lima was significantly associated with illness. While ETEC and NoV are commonly recognized as causative agents of outbreaks, co-circulation of both pathogens has been rarely observed in shipboard outbreaks
A Tabletop X-Ray Tomography Instrument for Nanometer-Scale Imaging: Integration of a Scanning Electron Microscope with a Transition-Edge Sensor Spectrometer
X-ray nanotomography is a powerful tool for the characterization of nanoscale
materials and structures, but is difficult to implement due to competing
requirements on X-ray flux and spot size. Due to this constraint,
state-of-the-art nanotomography is predominantly performed at large synchrotron
facilities. Compact X-ray nanotomography tools operated in standard analysis
laboratories exist, but are limited by X-ray optics and destructive sample
preparation techniques. We present a laboratory-scale nanotomography instrument
that achieves nanoscale spatial resolution while changing the limitations of
conventional tomography tools. The instrument combines the electron beam of a
scanning electron microscope (SEM) with the precise, broadband X-ray detection
of a superconducting transition-edge sensor (TES) microcalorimeter. The
electron beam generates a highly focused X-ray spot in a metal target, while
the TES spectrometer isolates target photons with high signal-to-noise. This
combination of a focused X-ray spot, energy-resolved X-ray detection, and
unique system geometry enable nanoscale, element-specific X-ray imaging in a
compact footprint. The proof-of-concept for this approach to X-ray
nanotomography is demonstrated by imaging 160 nm features in three dimensions
in a Cu-SiO2 integrated circuit, and a path towards finer resolution and
enhanced imaging capabilities is discussed.Comment: The following article has been submitted to Physical Review Applie
A tabletop x-ray tomography instrument for nanometer-scale imaging: demonstration of the 1,000-element transition-edge sensor subarray
We report on the 1,000-element transition-edge sensor (TES) x-ray
spectrometer implementation of the TOMographic Circuit Analysis Tool (TOMCAT).
TOMCAT combines a high spatial resolution scanning electron microscope (SEM)
with a highly efficient and pixelated TES spectrometer to reconstruct
three-dimensional maps of nanoscale integrated circuits (ICs). A 240-pixel
prototype spectrometer was recently used to reconstruct ICs at the 130 nm
technology node, but to increase imaging speed to more practical levels, the
detector efficiency needs to be improved. For this reason, we are building a
spectrometer that will eventually contain 3,000 TES microcalorimeters read out
with microwave superconducting quantum interference device (SQUID)
multiplexing, and we currently have commissioned a 1,000 TES subarray. This
still represents a significant improvement from the 240-pixel system and allows
us to begin characterizing the full spectrometer performance. Of the 992
maximimum available readout channels, we have yielded 818 devices, representing
the largest number of TES x-ray microcalorimeters simultaneously read out to
date. These microcalorimeters have been optimized for pulse speed rather than
purely energy resolution, and we measure a FWHM energy resolution of 14 eV at
the 8.0 keV Cu K line.Comment: 5 pages, 4 figures, submitted to IEEE Transactions on Applied
Superconductivit
A Model-Based Analysis of Chemical and Temporal Patterns of Cuticular Hydrocarbons in Male Drosophila melanogaster
Drosophila Cuticular Hydrocarbons (CH) influence courtship behaviour, mating, aggregation, oviposition, and resistance to desiccation. We measured levels of 24 different CH compounds of individual male D. melanogaster hourly under a variety of environmental (LD/DD) conditions. Using a model-based analysis of CH variation, we developed an improved normalization method for CH data, and show that CH compounds have reproducible cyclic within-day temporal patterns of expression which differ between LD and DD conditions. Multivariate clustering of expression patterns identified 5 clusters of co-expressed compounds with common chemical characteristics. Turnover rate estimates suggest CH production may be a significant metabolic cost. Male cuticular hydrocarbon expression is a dynamic trait influenced by light and time of day; since abundant hydrocarbons affect male sexual behavior, males may present different pheromonal profiles at different times and under different conditions
Human Uterine Wall Tension Trajectories and the Onset of Parturition
Uterine wall tension is thought to be an important determinant of the onset of labor in pregnant women. We characterize human uterine wall tension using ultrasound from the second trimester of pregnancy until parturition and compare preterm, term and twin pregnancies. A total of 320 pregnant women were followed from first antenatal visit to delivery during the period 2000â2004 at the John Hunter Hospital, NSW, Australia. The uterine wall thickness, length, anterior-posterior diameter and transverse diameter were determined by serial ultrasounds. Subjects were divided into three groups: women with singleton pregnancies and spontaneous labor onset, either preterm or term and women with twin pregnancies. Intrauterine pressure results from the literature were combined with our data to form trajectories for uterine wall thickness, volume and tension for each woman using the prolate ellipsoid method and the groups were compared at 20, 25 and 30 weeks gestation. Uterine wall tension followed an exponential curve, with results increasing throughout pregnancy with the site of maximum tension on the anterior wall. For those delivering preterm, uterine wall thickness was increased compared with term. For twin pregnancies intrauterine volume was increased compared to singletons (), but wall thickness was not. There was no evidence for increased tension in those delivering preterm or those with twin gestations. These data are not consistent with a role for high uterine wall tension as a causal factor in preterm spontaneous labor in singleton or twin gestations. It seems likely that hormonal differences in multiple gestations are responsible for increased rates of preterm birth in this group rather than increased tension
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
Host-Based Th2 Cell Therapy for Prolongation of Cardiac Allograft Viability
Donor T cell transfusion, which is a long-standing approach to prevent allograft rejection, operates indirectly by alteration of host T cell immunity. We therefore hypothesized that adoptive transfer of immune regulatory host Th2 cells would represent a novel intervention to enhance cardiac allograft survival. Using a well-described rat cardiac transplant model, we first developed a method for ex vivo manufacture of rat host-type Th2 cells in rapamycin, with subsequent injection of such Th2.R cells prior to class I and class II disparate cardiac allografting. Second, we determined whether Th2.R cell transfer polarized host immunity towards a Th2 phenotype. And third, we evaluated whether Th2.R cell therapy prolonged allograft viability when used alone or in combination with a short-course of cyclosporine (CSA) therapy. We found that host-type Th2.R cell therapy prior to cardiac allografting: (1) reduced the frequency of activated T cells in secondary lymphoid organs; (2) shifted post-transplant cytokines towards a Th2 phenotype; and (3) prolonged allograft viability when used in combination with short-course CSA therapy. These results provide further support for the rationale to use âdirectâ host T cell therapy for prolongation of allograft viability as an alternative to âindirectâ therapy mediated by donor T cell infusion
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