693 research outputs found
The Native American Graves Protection and Repatriation Act: Unresolved Issues Between Material Culture and Legal Definitions
Anomalous diffusion and collapse of self-gravitating Langevin particles in D dimensions
We address the generalized thermodynamics and the collapse of a system of
self-gravitating Langevin particles exhibiting anomalous diffusion in a space
of dimension D. The equilibrium states correspond to polytropic distributions.
The index n of the polytrope is related to the exponent of anomalous diffusion.
We consider a high-friction limit and reduce the problem to the study of the
nonlinear Smoluchowski-Poisson system. We show that the associated Lyapunov
functional is the Tsallis free energy. We discuss in detail the equilibrium
phase diagram of self-gravitating polytropes as a function of D and n and
determine their stability by using turning points arguments and analytical
methods. When no equilibrium state exists, we investigate self-similar
solutions describing the collapse. These results can be relevant for
astrophysical systems, two-dimensional vortices and for the chemotaxis of
bacterial populations. Above all, this model constitutes a prototypical
dynamical model of systems with long-range interactions which possesses a rich
structure and which can be studied in great detail.Comment: Submitted to Phys. Rev.
Optical coherence tomography in the assessment of acute changes in cutaneous vascular diameter induced by heat stress.
There are limited imaging technologies available that can accurately assess or provide surrogate markers of the in vivo cutaneous microvessel network in humans. In this study, we establish the use of optical coherence tomography (OCT) as a novel imaging technique to assess acute changes in cutaneous microvessel area density and diameter in humans. OCT speckle decorrelation images of the skin on the ventral side of the forearm up to a depth of 500 Όm were obtained prior to and following 20-25 mins of lower limb heating in eight healthy males (30.3±7.6 yrs). Skin red blood cell flux was also collected using laser Doppler flowmetry probes immediately adjacent to the OCT skin sites, along with skin temperature. OCT speckle decorrelation images were obtained at both baseline and heating time points. Forearm skin flux increased significantly (0.20±0.15 to 1.75±0.38 CVC, P<0.01), along with forearm skin temperature (32.0±1.2 to 34.3±1.0°C, P<0.01). Quantitative differences in the automated calculation of vascular area densities (26±9 to 49±19%, P<0.01) and individual microvessel diameters (68±17 to 105±25 Όm, P<0.01) were evident following the heating session. This is the first in vivo within-subject assessment of acute changes in the cutaneous microvasculature in response to heating in humans and highlights the use of OCT as an exciting new imaging approach for skin physiology and clinical research
The National Childrens Study: An Introduction and Historical Overview
The National Childrenâs Study (NCS) was an ambitious attempt to map childrenâs health and development in a large representative group of children in the United States. In this introduction, we briefly review the background of the NCS and the history of the multiple strategies that were tested to recruit women and children. Subsequent articles then detail the protocols and outcomes of 4 of the recruitment strategies. It is hoped that lessons learned from these attempts to define a study protocol that could achieve the initial aims of the NCS will inform future efforts to conceptualize and execute strategies to provide generalizable insights on the longitudinal health of our nationâs children
Spectrum monitoring and analysis with the AMD RFSoC
The Radio Frequency (RF) spectrum is a finite resource that requires strict regulation to prevent illegitimate use and unauthorised transmissions. Spectrum monitoring (measurement and analysis) is key to supporting regulation by determining usage and occupancy in real-time as well as establishing temporal trends. Spectrum monitoring technology can also enable Dynamic Spectrum Access (DSA) solutions, which improve the efficiency of the radio spectrum by autonomously adjusting wireless communication networks in real-time. DSA techniques require knowledge of real-time spectrum occupancy and a historical database of past usage. Engineers from the University of Strathclyde and Advanced Micro Devices (AMD) have developed an innovative spectrum monitoring solution that aims to improve spectrum regulation and enable real-time DSA techniques. This solution features an open-source software stack and hardware design to measure the power of ambient radio signals and record the frequency spectrum over time. The system is also able to combine spectrum measurements alongside a local database of frequency band allocations published by Ofcom (UK regulator). Thus, the spectrum monitoring solution can identify in-use frequency bands and the organisation(s) that can legitimately use them. The solution is implemented entirely on AMDâs Radio Frequency System on Chip (RFSoC) device, which features high-speed data converters for accurately performing wide-bandwidth measurements of the frequency spectrum. Autonomous vehicles, media and broadcast technologies, and smart manufacturing environments increasingly require DSA to overcome wireless communication congestion. DSA techniques are essential to improve the efficient allocation of the RF spectrum. This spectrum monitoring solution addresses the challenge of implementing DSA techniques by providing a cost-effective, real-time solution for efficiently measuring and recording the ambient radio spectrum. For example, the spectrum monitor can be deployed alongside a 4G/5G mobile base station and can probe the local radio spectrum to inform the base station as to the most suitable frequency bands for wireless communication
Spitzer reveals what's behind Orion's Bar
We present Spitzer Space Telescope observations of 11 regions SE of the
Bright Bar in the Orion Nebula, along a radial from the exciting star
theta1OriC, extending from 2.6 to 12.1'. Our Cycle 5 programme obtained deep
spectra with matching IRS short-high (SH) and long-high (LH) aperture grid
patterns. Most previous IR missions observed only the inner few arcmin. Orion
is the benchmark for studies of the ISM particularly for elemental abundances.
Spitzer observations provide a unique perspective on the Ne and S abundances by
virtue of observing the dominant ionization states of Ne (Ne+, Ne++) and S
(S++, S3+) in Orion and H II regions in general. The Ne/H abundance ratio is
especially well determined, with a value of (1.01+/-0.08)E-4. We obtained
corresponding new ground-based spectra at CTIO. These optical data are used to
estimate the electron temperature, electron density, optical extinction, and
the S+/S++ ratio at each of our Spitzer positions. That permits an adjustment
for the total gas-phase S abundance because no S+ line is observed by Spitzer.
The gas-phase S/H abundance ratio is (7.68+/-0.30)E-6. The Ne/S abundance ratio
may be determined even when the weaker hydrogen line, H(7-6) here, is not
measured. The mean value, adjusted for the optical S+/S++ ratio, is Ne/S =
13.0+/-0.6. We derive the electron density versus distance from theta1OriC for
[S III] and [S II]. Both distributions are for the most part decreasing with
increasing distance. A dramatic find is the presence of high-ionization Ne++
all the way to the outer optical boundary ~12' from theta1OriC. This IR result
is robust, whereas the optical evidence from observations of high-ionization
species (e.g. O++) at the outer optical boundary suffers uncertainty because of
scattering of emission from the much brighter inner Huygens Region.Comment: 60 pages, 16 figures, 10 tables. MNRAS accepte
A Descriptive, Multiyear Examination of Positive Behavior Support
A major goal of positive behavior support (PBS) is to produce broad-based, long-term improvements in adaptive behavior; however, the empirical base, at present, is mainly composed of relatively short-term studies carried out in circumscribed contexts. Therefore, a need exists for reliable data that can inform the field regarding the comprehensive lifestyle effects of PBS implementation in natural community contexts over extended periods of time. The current investigation was conducted to provide a descriptive analysis of PBS with diverse participants and broad measurement strategies over multiple years. Using extensive data portfolios for 21 participants, we employed rating scales to quantify changes in key variables from baseline through 2 years of intervention. The data revealed variable levels of intervention integrity, generalized reductions in problem behavior with occasional relapses, and encouraging enhancements across six domains of quality of life. This study represents an initial attempt to understand the processes and outcomes of behavioral support by documenting behavioral patterns across full days, entire years, and all environments. We discuss the need to consider new conceptual and methodological frameworks for further study of efficacious and sustainable behavior support
BBF RFC 112: Synthetic Biology Open Language (SBOL) Version 2.1.0
BBF RFC 112 (the SBOL 2.1.0 standard) replaces BBF RFC 108 (the SBOL 2.0 standard), as well as the minor update SBOL 2.0.1.The Synthetic Biology Open Language (SBOL) has been developed as a standard to support the specification and exchange of biological design information
Multi-Messenger Gravitational Wave Searches with Pulsar Timing Arrays: Application to 3C66B Using the NANOGrav 11-year Data Set
When galaxies merge, the supermassive black holes in their centers may form
binaries and, during the process of merger, emit low-frequency gravitational
radiation in the process. In this paper we consider the galaxy 3C66B, which was
used as the target of the first multi-messenger search for gravitational waves.
Due to the observed periodicities present in the photometric and astrometric
data of the source of the source, it has been theorized to contain a
supermassive black hole binary. Its apparent 1.05-year orbital period would
place the gravitational wave emission directly in the pulsar timing band. Since
the first pulsar timing array study of 3C66B, revised models of the source have
been published, and timing array sensitivities and techniques have improved
dramatically. With these advances, we further constrain the chirp mass of the
potential supermassive black hole binary in 3C66B to less than using data from the NANOGrav 11-year data set. This
upper limit provides a factor of 1.6 improvement over previous limits, and a
factor of 4.3 over the first search done. Nevertheless, the most recent orbital
model for the source is still consistent with our limit from pulsar timing
array data. In addition, we are able to quantify the improvement made by the
inclusion of source properties gleaned from electromagnetic data to `blind'
pulsar timing array searches. With these methods, it is apparent that it is not
necessary to obtain exact a priori knowledge of the period of a binary to gain
meaningful astrophysical inferences.Comment: 14 pages, 6 figures. Accepted by Ap
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