4,856 research outputs found
Single Event Effects (SEE) Testing of Embedded DSP Cores within Microsemi RTAX4000D Field Programmable Gate Array (FPGA) Devices
Motivation for this work is: (1) Accurately characterize digital signal processor (DSP) core single-event effect (SEE) behavior (2) Test DSP cores across a large frequency range and across various input conditions (3) Isolate SEE analysis to DSP cores alone (4) Interpret SEE analysis in terms of single-event upsets (SEUs) and single-event transients (SETs) (5) Provide flight missions with accurate estimate of DSP core error rates and error signatures
Star Formation in a Stellar Mass Selected Sample of Galaxies to z=3 from the GOODS NICMOS Survey (GNS)
We present a study of the star-forming properties of a stellar mass-selected
sample of galaxies in the GOODS NICMOS Survey (GNS), based on deep Hubble Space
Telescope imaging of the GOODS North and South fields. Using a stellar mass
selected sample, combined with HST/ACS and Spitzer data to measure both UV and
infrared derived star formation rates (SFR), we investigate the star forming
properties of a complete sample of ~1300 galaxies down to log M*=9.5 at
redshifts 1.5<z<3. Eight percent of the sample is made up of massive galaxies
with M*>10^11 Msun. We derive optical colours, dust extinctions, and
ultraviolet and infrared SFR to determine how the star formation rate changes
as a function of both stellar mass and time. Our results show that SFR
increases at higher stellar mass such that massive galaxies nearly double their
stellar mass from star formation alone over the redshift range studied, but the
average value of SFR for a given stellar mass remains constant over this 2 Gyr
period. Furthermore, we find no strong evolution in the SFR for our sample as a
function of mass over our redshift range of interest, in particular we do not
find a decline in the SFR among massive galaxies, as is seen at z < 1. The most
massive galaxies in our sample (log M*>11) have high average SFRs with values,
SFR(UV,corr) = 103+/-75 Msun/yr, yet exhibit red rest-frame (U-B) colours at
all redshifts. We conclude that the majority of these red high-redshift massive
galaxies are red due to dust extinction. We find that A(2800) increases with
stellar mass, and show that between 45% and 85% of massive galaxies harbour
dusty star formation. These results show that even just a few Gyr after the
first galaxies appear, there are strong relations between the global physical
properties of galaxies, driven by stellar mass or another underlying feature of
galaxies strongly related to the stellar mass.Comment: 18 pages, 10 figures, accepted for publication in MNRA
Early queen infection shapes developmental dynamics and induces long-term disease protection in incipient ant colonies
Infections early in life can have enduring effects on an organism's development and immunity. In this study, we show that this equally applies to developing ‘superorganisms’––incipient social insect colonies. When we exposed newly mated Lasius niger ant queens to a low pathogen dose, their colonies grew more slowly than controls before winter, but reached similar sizes afterwards. Independent of exposure, queen hibernation survival improved when the ratio of pupae to workers was small. Queens that reared fewer pupae before worker emergence exhibited lower pathogen levels, indicating that high brood rearing efforts interfere with the ability of the queen's immune system to suppress pathogen proliferation. Early-life queen pathogen exposure also improved the immunocompetence of her worker offspring, as demonstrated by challenging the workers to the same pathogen a year later. Transgenerational transfer of the queen's pathogen experience to her workforce can hence durably reduce the disease susceptibility of the whole superorganism
Relativistic Diskoseismology. I. Analytical Results for 'Gravity Modes'
We generalize previous calculations to a fully relativistic treatment of
adiabatic oscillations which are trapped in the inner regions of accretion
disks by non-Newtonian gravitational effects of a black hole. We employ the
Kerr geometry within the scalar potential formalism of Ipser and Lindblom,
neglecting the gravitational field of the disk. This approach treats
perturbations of arbitrary stationary, axisymmetric, perfect fluid models. It
is applied here to thin accretion disks. Approximate analytic eigenfunctions
and eigenfrequencies are obtained for the most robust and observable class of
modes, which corresponds roughly to the gravity (internal) oscillations of
stars. The dependence of the oscillation frequencies on the mass and angular
momentum of the black hole is exhibited. These trapped modes do not exist in
Newtonian gravity, and thus provide a signature and probe of the strong-field
structure of black holes. Our predictions are relevant to observations which
could detect modulation of the X-ray luminosity from stellar mass black holes
in our galaxy and the UV and optical luminosity from supermassive black holes
in active galactic nuclei.Comment: 31 pages, 6 figures, uses style file aaspp4.sty, prepared with the
AAS LATEX macros v4.0, significant revision of earlier submission to include
modes with axial index m>
Online health information for penile prosthesis implants lacks quality and is unreadable to the average US patient
BACKGROUND: Online health information (OHI) has become widely accessible and affects patient decisions regarding their healthcare. The purpose of this study was to assess the readability, quality, and accuracy of information available to patients online about penile prosthesis implants (PPIs).
METHODS: We performed a Google search using the keywords penile implant and penile prosthesis. The first 30 search results for both terms were analyzed, and advertisements, news articles, duplicates, and videos were excluded. Websites were categorized as institutional, commercial, and personal/patient support. Readability of each website was determined using the Flesch-Kincaid grade level (FKGL) readability formula within the readable tool. Quality was measured by Health On the Net (HON) certification status and the DISCERN scoring method. For website accuracy, a score of 1-4 (1=0-25%, 2=25-50%, 3=50-75%, and 4=75-100%) was assigned.
RESULTS: Forty-four websites met the criteria (23 institutional, 12 commercial, and 9 personal/patient support). The mean total FKGL score was 9.55. No statistical difference was detected between mean FKGL for each website category (p=0.69). Only eight websites (18%) scored ≤8th-grade reading level (average US adult level), while 36 (82%) were \u3e8th-grade level. Mean total DISCERN sum score was 39.74/75, with no statistical difference in mean DISCERN score between website types (p=0.08). Over half (55%) of the websites were defined as very poor or poor quality by DISCERN scoring. Mean total overall quality rating was 2.67/5. HON certification was verified for only nine websites (20%). Twenty-five percent of websites were classified as 0-25% accurate, 23% were 25-50% accurate, 30% were 50-75% accurate, and 23% were 75-100% accurate.
CONCLUSION: Most information on the Internet about PPIs is reasonably accurate; however, the majority of websites are deficient in quality and unreadable to the average patient, irrespective of website type
Genetic Structure of Faucet Snail, Bithynia tentaculata Populations in North America, Based on Microsatellite Markers
Bithynia tentaculata is believed to have been extirpated from North America during the last glacial maximum. It was reintroduced into North America via the Great Lakes basin in the 1800’s and has recently been expanding its geographic range. This snail serves as intermediate host for three trematodes that cause extensive recurring morbidity and mortality events in migratory water birds along the Mississippi River. Using twelve microsatellite loci for ~200 individual snails from 11populations in North America and Europe, we examined one of the three major geographic regions from which founding populations into the Great Lakes typically originate. Our data supports a single colonization of North America into the Great Lakes Basin followed by subsequent introduction events from the Great Lakes to other large watersheds in North America. However, additional watersheds in Europe require sampling to confirm this result. No populations with genetic signatures indicative of North American glacial relics were found. The initial invasion of North America was likely not from the Ponto-Caspian basin, the usual source of freshwater invasive species to the Laurentian Great Lake
Effects of Inherent Tissue Anisotropy on Measurements Obtained with a Clinical Ultrasonic Imaging System
Our overall goal is to develop clinically applicable tissue characterization methods, based on quantitative analyses of backscattered ultrasound, which can differentiate normal from diseased heart segments. In implementing these methods there is a need to compensate for the inherent anisotropic properties of the heart that are exhibited in echocardiographic images. [1–4] Furthermore, quantitative tissue characterization methods may be able to exploit the inherent anisotropy of the myocardium to achieve assessment of cardiac properties.[5–9] The specific aims of this investigation were to measure the spectral properties of backscattered ultrasound using a clinical imaging system and to determine effects of inherent tissue anisotropy on measured spectral properties of backscattered ultrasound
Phase change dynamics and 2-dimensional 4-bit memory in Ge2Sb2Te5 via telecom-band encoding
As modern computing gets continuously pushed up against the von Neumann
Bottleneck -- limiting the ultimate speeds for data transfer and computation --
new computing methods are needed in order to bypass this issue and keep our
computer's evolution moving forward, such as hybrid computing with an optical
co-processor, all-optical computing, or photonic neuromorphic computing. In any
of these protocols, we require an optical memory: either a
multilevel/accumulator memory, or a computational memory. Here, we propose and
demonstrate a 2-dimensional 4-bit fully optical non-volatile memory using
Ge2Sb2Te5 (GST) phase change materials, with encoding via a 1550 nm laser.
Using the telecom-band laser, we are able to reach deeper into the material due
to the low-loss nature of GST at this wavelength range, hence increasing the
number of optical write/read levels compared to previous demonstrations, while
simultaneously staying within acceptable read/write energies. We verify our
design and experimental results via rigorous numerical simulations based on
finite element and nucleation theory, and we successfully write and read a
string of characters using direct hexadecimal encoding
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