2,277 research outputs found
Low Frequency Radio Constraints on the Synchrotron Cosmic Web
We present a search for the synchrotron emission from the synchrotron cosmic
web by cross correlating 180MHz radio images from the Murchison Widefield Array
with tracers of large scale structure (LSS). We use two versions of the radio
image covering degrees with point sources brighter than
0.05 Jy subtracted, with and without filtering of Galactic emission. As tracers
of the LSS we use the Two-Micron-All-Sky-Survey (2MASS) and the Widefield
InfraRed Explorer (WISE) redshift catalogues to produce galaxy number density
maps. The cross correlation functions all show peak amplitudes at zero degrees,
decreasing with varying slopes towards zero correlation over a range of one
degree. The cross correlation signals include components from point source,
Galactic, and extragalactic diffuse emission. We use models of the diffuse
emission from smoothing the density maps with Gaussians of sizes 1-4 Mpc to
find limits on the cosmic web components. From these models we find surface
brightness 99.7 per cent upper limits in the range of 0.09-2.20 mJy beam
(average beam size of 2.6 arcmin), corresponding to 0.01-0.30 mJy
arcmin. Assuming equipartition between energy densities of cosmic rays
and the magnetic field, the flux density limits translate to magnetic field
strength limits of 0.03-1.98 G, depending heavily on the spectral index.
We conclude that for a 3 detection of 0.1 G magnetic field
strengths via cross correlations, image depths of sub-mJy to sub-Jy are
necessary. We include discussion on the treatment and effect of extragalactic
point sources and Galactic emission, and next steps for building on this work.Comment: 25 pages, 18 figures, 4 tables, accepted for publication in MNRA
Automated Discovery of Flight Track Anomalies
As new technologies are developed to handle the complexities of the Next Generation Air Transportation System (NextGen), it is increasingly important to address both current and future safety concerns along with the operational, environmental, and efficiency issues within the National Airspace System (NAS). In recent years, the Federal Aviation Administrations (FAA) safety offices have been researching ways to utilize the many safety databases maintained by the FAA, such as those involving flight recorders, radar tracks, weather, and many other high- volume sensors, in order to monitor this unique and complex system. Although a number of current technologies do monitor the frequency of known safety risks in the NAS, very few methods currently exist that are capable of analyzing large data repositories with the purpose of discovering new and previously unmonitored safety risks. While monitoring the frequency of known events in the NAS enables mitigation of already identified problems, a more proactive approach of finding unidentified issues still needs to be addressed. This is especially important in the proactive identification of new, emergent safety issues that may result from the planned introduction of advanced NextGen air traffic management technologies and procedures. Development of an automated tool that continuously evaluates the NAS to discover both events exhibiting flight characteristics indicative of safety-related concerns as well as operational anomalies will heighten the awareness of such situations in the aviation community and serve to increase the overall safety of the NAS. This paper discusses the extension of previous anomaly detection work to identify operationally significant flights within the highly complex airspace encompassing the New York area of operations, focusing on the major airports of Newark International (EWR), LaGuardia International (LGA), and John F. Kennedy International (JFK). In addition, flight traffic in the vicinity of Denver International (DEN) airport/airspace is also investigated to evaluate the impact on operations due to variances in seasonal weather and airport elevation. From our previous research, subject matter experts determined that some of the identified anomalies were significant, but could not reach conclusive findings without additional supportive data. To advance this research further, causal examination using domain experts is continued along with the integration of air traffic control (ATC) voice data to shed much needed insight into resolving which flight characteristic(s) may be impacting an aircraft's unusual profile. Once a flight characteristic is identified, it could be included in a list of potential safety precursors. This paper also describes a process that has been developed and implemented to automatically identify and produce daily reports on flights of interest from the previous day
Shoshoni Conceptualizations of Plant Relationships
Interviews were conducted with 10 Shoshoni-speaking people to investigate conceptualizations of plant relationships. A card-sort technique and informal questioning were employed in an attempt to elicit plant classifications and taxonomic relationships. Results indicate classifications are based on multiple criteria including morphology, cultural utilization, geographic setting and growth habit. A paradigm which postulates conceptualizations based on prototypic images fits the data better than the supposition that memory is composed of extensive taxonomic structures
Impact of acamprosate on plasma amyloid-β precursor protein in youth: a pilot analysis in fragile X syndrome-associated and idiopathic autism spectrum disorder suggests a pharmacodynamic protein marker
BACKGROUND: Understanding of the pathophysiology of autism spectrum disorder (ASD) remains limited. Brain overgrowth has been hypothesized to be associated with the development of ASD. A derivative of amyloid-β precursor protein (APP), secreted APPα (sAPPα), has neuroproliferative effects and has been shown to be elevated in the plasma of persons with ASD compared to control subjects. Reduction in sAPPα holds promise as a novel molecular target of treatment in ASD. Research into the neurochemistry of ASD has repeatedly implicated excessive glutamatergic and deficient GABAergic neurotransmission in the disorder. With this in mind, acamprosate, a novel modulator of glutamate and GABA function, has been studied in ASD. No data is available on the impact of glutamate or GABA modulation on sAPPα function.
METHODS: Plasma APP derivative levels pre- and post-treatment with acamprosate were determined in two pilot studies involving youth with idiopathic and fragile X syndrome (FXS)-associated ASD. We additionally compared baseline APP derivative levels between youth with FXS-associated or idiopathic ASD.
RESULTS: Acamprosate use was associated with a significant reduction in plasma sAPP(total) and sAPPα levels but no change occurred in Aβ40 or Aβ42 levels in 15 youth with ASD (mean age: 11.1 years). Youth with FXS-associated ASD (n = 12) showed increased sAPPα processing compared to age-, gender- and IQ-match youth with idiopathic ASD (n = 11).
CONCLUSIONS: Plasma APP derivative analysis holds promise as a potential biomarker for use in ASD targeted treatment. Reduction in sAPP (total) and sAPPα may be a novel pharmacodynamic property of acamprosate. Future study is required to address limitations of the current study to determine if baseline APP derivative analysis may predict subgroups of persons with idiopathic or FXS-associated ASD who may respond best to acamprosate or to potentially other modulators of glutamate and/or GABA neurotransmission
Enumerative geometry of Calabi-Yau 4-folds
Gromov-Witten theory is used to define an enumerative geometry of curves in
Calabi-Yau 4-folds. The main technique is to find exact solutions to moving
multiple cover integrals. The resulting invariants are analogous to the BPS
counts of Gopakumar and Vafa for Calabi-Yau 3-folds. We conjecture the 4-fold
invariants to be integers and expect a sheaf theoretic explanation.
Several local Calabi-Yau 4-folds are solved exactly. Compact cases, including
the sextic Calabi-Yau in CP5, are also studied. A complete solution of the
Gromov-Witten theory of the sextic is conjecturally obtained by the holomorphic
anomaly equation.Comment: 44 page
Angiotensin-(1-7) and angiotensin-(1-9): function in cardiac and vascular remodeling
The renin angiotensin system (RAS) is integral to cardiovascular physiology, however, dysregulation of this system largely contributes to the pathophysiology of cardiovascular disease (CVD). It is well established that angiotensin II (Ang II), the main effector of the RAS, engages the angiotensin type 1 receptor and promotes cell growth, proliferation, migration and oxidative stress, all processes which contribute to remodeling of the heart and vasculature, ultimately leading to the development and progression of various CVDs including heart failure and atherosclerosis. The counter-regulatory axis of the RAS, which is centered on the actions of angiotensin converting enzyme 2 (ACE2) and the resultant production of angiotensin-(1-7) (Ang-(1-7) from Ang II, antagonizes the actions of Ang II via the receptor Mas, thereby providing a protective role in CVD. More recently, another ACE2 metabolite, Ang-(1-9), has been reported to be a biologically active peptide within the counter-regulatory axis of the RAS. This review will discuss the role of the counter-regulatory RAS peptides, Ang-(1-7) and Ang-(1-9) in the cardiovascular system, with a focus on their effects in remodeling of the heart and vasculature
Variables Affecting Motivation For Father Involvement: A Self-Determination Approach
The present study was designed to assess the predictive relationships between motivation and father involvement from the perspective of Self-Determination Theory (Ryan & Deci, 2000) for married fathers with at least one elementary-aged child. A sample (N=260) composed primarily of Caucasian and middle-class fathers provided information regarding their motivation to be involved in various fathering tasks and their perceived involvement with their child(ren). Path analysis was used to assess predictive relationships between the innate needs in Self-Determination Theory (Autonomy, Competence, and Relatedness) with the Motivation for Father Involvement Scale (MFIS) (Bouchard & Lee, 2007) as well as the relationship between motivation and father involvement and parental satisfaction. An ad hoc path model revealed predictive relationships between relatedness and competence with internalized motivation. In addition, scores of internalized motivation were predictive of perceived father involvement and parental satisfaction
The HST/ACS Coma Cluster Survey. II. Data Description and Source Catalogs
The Coma cluster was the target of a HST-ACS Treasury program designed for
deep imaging in the F475W and F814W passbands. Although our survey was
interrupted by the ACS instrument failure in 2007, the partially completed
survey still covers ~50% of the core high-density region in Coma. Observations
were performed for 25 fields that extend over a wide range of cluster-centric
radii (~1.75 Mpc) with a total coverage area of 274 arcmin^2. The majority of
the fields are located near the core region of Coma (19/25 pointings) with six
additional fields in the south-west region of the cluster. In this paper we
present reprocessed images and SExtractor source catalogs for our survey
fields, including a detailed description of the methodology used for object
detection and photometry, the subtraction of bright galaxies to measure faint
underlying objects, and the use of simulations to assess the photometric
accuracy and completeness of our catalogs. We also use simulations to perform
aperture corrections for the SExtractor Kron magnitudes based only on the
measured source flux and half-light radius. We have performed photometry for
~73,000 unique objects; one-half of our detections are brighter than the
10-sigma point-source detection limit at F814W=25.8 mag (AB). The slight
majority of objects (60%) are unresolved or only marginally resolved by ACS. We
estimate that Coma members are 5-10% of all source detections, which consist of
a large population of unresolved objects (primarily GCs but also UCDs) and a
wide variety of extended galaxies from a cD galaxy to dwarf LSB galaxies. The
red sequence of Coma member galaxies has a constant slope and dispersion across
9 magnitudes (-21<M_F814W<-13). The initial data release for the HST-ACS Coma
Treasury program was made available to the public in 2008 August. The images
and catalogs described in this study relate to our second data release.Comment: Accepted for publication in ApJS. A high-resolution version is
available at http://archdev.stsci.edu/pub/hlsp/coma/release2/PaperII.pd
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