3,810 research outputs found

    Improved Time-Domain Accuracy Standards for Model Gravitational Waveforms

    Get PDF
    Model gravitational waveforms must be accurate enough to be useful for detection of signals and measurement of their parameters, so appropriate accuracy standards are needed. Yet these standards should not be unnecessarily restrictive, making them impractical for the numerical and analytical modelers to meet. The work of Lindblom, Owen, and Brown [Phys. Rev. D 78, 124020 (2008)] is extended by deriving new waveform accuracy standards which are significantly less restrictive while still ensuring the quality needed for gravitational-wave data analysis. These new standards are formulated as bounds on certain norms of the time-domain waveform errors, which makes it possible to enforce them in situations where frequency-domain errors may be difficult or impossible to estimate reliably. These standards are less restrictive by about a factor of 20 than the previously published time-domain standards for detection, and up to a factor of 60 for measurement. These new standards should therefore be much easier to use effectively.Comment: 10 pages, 5 figure

    EFFECT OF GENETIC POTENTIAL AND FEED ON GROWTH OF YOUNG BULLS FOR FUTURE BREEDING

    Get PDF
    Over a five-year period (1985-1989), a total of 239 bull calves (Angus=119, Hereford=120) were weaned and placed on summer pasture or fed grain concentrate in a feedlot for purpose of studying growth rate of body weight, hip height, and scrotal circumference over 189 days. Average daily gain [ADG, (final wt - weaning wt) / days in period] has been the standard measure of gwwth. However, this does not address how well a particular bull might have performed. ADG values were ranked at each measurement period (0, 21,49,77, 105, 133,161 and 189 days after weaning), changes in rank were determined for each bull, and the data analyzed. Bulls with higher genetic potential and those on the grain-fed diet showed positive rank changes over the 189 days. It was concluded that rank changes would be the best measure of superior growth for future breeding purposes. It ,vas discovered that a bull, poorly prepared (genetic or environmental) prior to weaning, could overcome this if placed on the grain-fed diet

    A modified Oster-Murray-Harris mechanical model of morphogenesis

    Get PDF
    There are two main modeling paradigms for biological pattern formation in developmental biology: chemical prepattern models and cell aggregation models. This paper focuses on an example of a cell aggregation model, the mechanical model developed by Oster, Murray, and Harris [Development, 78 (1983), pp. 83--125]. We revisit the Oster--Murray--Harris model and find that, due to the infinitesimal displacement assumption made in the original version of this model, there is a restriction on the types of boundary conditions that can be prescribed. We derive a modified form of the model which relaxes the infinitesimal displacement assumption. We analyze the dynamics of this model using linear and multiscale nonlinear analysis and show that it has the same linear behavior as the original Oster--Murray--Harris model. Nonlinear analysis, however, predicts that the modified model will allow for a wider range of parameters where the solution evolves to a bounded steady state. The results from both analyses are verified through numerical simulations of the full nonlinear model in one and two dimensions. The increased range of boundary conditions that are well-posed, as well as a wider range of parameters that yield bounded steady states, renders the modified model more applicable to, and more robust for, comparisons with experiments

    Implant-Based Reconstruction following Mastectomy in Patients Who Have Had a Previous Breast Augmentation:Lessons from the National Multicenter Implant Breast Reconstruction Evaluation Study

    Get PDF
    Background: Breast augmentation is the most commonly performed cosmetic procedure, and increasingly women in this group present with breast cancer or request risk-reducing surgery, but their optimal management is unclear. The authors explored the clinical and patient-reported outcomes of patients undergoing immediate implant-based breast reconstruction following previous augmentation and compared these with outcomes of patients who had not had cosmetic implants in the Implant Breast Reconstruction Evaluation (iBRA) Study.   Methods: Patients undergoing immediate implant-based breast reconstruction were prospectively recruited from breast and plastic surgical units across the United Kingdom. Demographic, operative, and oncologic data, and information regarding complications within 3 postoperative months were collected. Patient-reported outcomes at 18 months were assessed using the BREAST-Q. The clinical and patient-reported outcomes of patients undergoing immediate implant-based breast reconstruction with and without previous breast augmentation were compared.   Results: A total of 2108 women were included in the iBRA Study, of whom 49 had undergone a previous augmentation. Women in the augmentation group were younger (median age, 45 years versus 50 years; p = 0.01), had a lower body mass index (22.8 kg/m2 versus 24.9 kg/m2; p < 0.01), and had smaller tumors (15 mm versus 25 mm; p = 0.01) than patients without augmentation. No differences were seen in operative technique between the groups. Complications at 3 months were similar in both groups and there were no significant differences in patient-reported outcomes at 18 months.   Conclusions: The clinical and patient-reported outcomes of patients undergoing immediate implant-based breast reconstruction following previous augmentation are consistent with those observed in the wider iBRA Study cohort, supporting the safety of this approach

    Uncertainties in Theoretical HeI Emissivities: HII Regions, Primordial Abundance, and Cosmological Recombination

    Get PDF
    A number of recent works in astronomy and cosmology have relied upon theoretical He I emissivities, but we know of no effort to quantify the uncertainties in the atomic data. We analyze and assign uncertainties to all relevant atomic data, perform Monte Carlo analyses, and report standard deviations in the line emissivities. We consider two sets of errors, which we call "optimistic" and "pessimistic." We also consider three different conditions, corresponding to prototypical Galactic and extragalactic H II regions and the epoch of cosmological recombination. In the extragalactic H II case, the errors we obtain are comparable to or larger than the errors in some recent YpY_p calculations, including those derived from CMB observations. We demonstrate a systematic effect on primordial abundance calculations; this effect cannot be reduced by observing a large number of objects. In the cosmological recombination case, the errors are comparable to many of the effects considered in recent calculations.Comment: 5 pages, 3 figures, accepted to MNRAS Letter

    Trends in Decline of Antiretroviral Resistance among ARV-Experienced Patients in the HIV Outpatient Study: 1999–2008

    Get PDF
    Background. Little is known about temporal trends in frequencies of clinically relevant ARV resistance mutations in HIV strains from U.S. patients undergoing genotypic testing (GT) in routine HIV care. Methods. We analyzed cumulative frequency of HIV resistance among patients in the HIV Outpatient Study (HOPS) who, during 1999–2008 and while prescribed antiretrovirals, underwent GT with plasma HIV RNA >1,000 copies/mL. Exposure ≥4 months to each of three major antiretroviral classes (NRTI, NNRTI and PI) was defined as triple-class exposure (TCE). Results. 906 patients contributed 1,570 GT results. The annual frequency of any major resistance mutations decreased during 1999–2008 (88% to 79%, P = 0.05). Resistance to PIs decreased among PI-exposed patients (71% to 46%, P = 0.010) as exposure to ritonavir-boosted PIs increased (6% to 81%, P < 0.001). Non-significant declines were observed in resistance to NRTIs among NRTI-exposed (82% to 67%), and triple-class-resistance among TCE patients (66% to 41%), but not to NNRTIs among NNRTI-exposed. Conclusions. HIV resistance was common but declined in HIV isolates from subgroups of ARV-experienced HOPS patients during 1999–2008. Resistance to PIs among PI-exposed patients decreased, possibly due to increased representation of patients whose only PI exposures were to boosted PIs

    Transcriptomic analysis of field-droughted sorghum from seedling to maturity reveals biotic and metabolic responses.

    Get PDF
    Drought is the most important environmental stress limiting crop yields. The C4 cereal sorghum [Sorghum bicolor (L.) Moench] is a critical food, forage, and emerging bioenergy crop that is notably drought-tolerant. We conducted a large-scale field experiment, imposing preflowering and postflowering drought stress on 2 genotypes of sorghum across a tightly resolved time series, from plant emergence to postanthesis, resulting in a dataset of nearly 400 transcriptomes. We observed a fast and global transcriptomic response in leaf and root tissues with clear temporal patterns, including modulation of well-known drought pathways. We also identified genotypic differences in core photosynthesis and reactive oxygen species scavenging pathways, highlighting possible mechanisms of drought tolerance and of the delayed senescence, characteristic of the stay-green phenotype. Finally, we discovered a large-scale depletion in the expression of genes critical to arbuscular mycorrhizal (AM) symbiosis, with a corresponding drop in AM fungal mass in the plants' roots

    Ultrafast all-optical chalcogenide glass photonic circuits

    No full text
    Chalcogenide glasses offer large ultrafast third-order nonlinearities, low two-photon absorption and the absence of free carrier absorption in a photosensitive medium. This unique combination of properties is nearly ideal for all-optical signal processing devices. In this paper we review the key properties of these materials, outline progress in the field and focus on several recent highlights: high quality gratings, signal regeneration, pulse compression and wavelength conversion

    Searching for Sharp Drops in the Incidence of Pandemic A/H1N1 Influenza by Single Year of Age

    No full text
    BACKGROUND During the 2009 H1N1 pandemic (pH1N1), morbidity and mortality sparing was observed among the elderly population; it was hypothesized that this age group benefited from immunity to pH1N1 due to cross-reactive antibodies generated from prior infection with antigenically similar influenza viruses. Evidence from serologic studies and genetic similarities between pH1N1 and historical influenza viruses suggest that the incidence of pH1N1 cases should drop markedly in age cohorts born prior to the disappearance of H1N1 in 1957, namely those at least 52-53 years old in 2009, but the precise range of ages affected has not been delineated. METHODS AND FINDINGS To test for any age-associated discontinuities in pH1N1 incidence, we aggregated laboratory-confirmed pH1N1 case data from 8 jurisdictions in 7 countries, stratified by single year of age, sex (when available), and hospitalization status. Using single year of age population denominators, we generated smoothed curves of the weighted risk ratio of pH1N1 incidence, and looked for sharp drops at varying age bandwidths, defined as a significantly negative second derivative. Analyses stratified by hospitalization status and sex were used to test alternative explanations for observed discontinuities. We found that the risk of laboratory-confirmed infection with pH1N1 declines with age, but that there was a statistically significant leveling off or increase in risk from about 45 to 50 years of age, after which a sharp drop in risk occurs until the late fifties. This trend was more pronounced in hospitalized cases and in women and was independent of the choice in smoothing parameters. The age range at which the decline in risk accelerates corresponds to the cohort born between 1951-1959 (hospitalized) and 1953-1960 (not hospitalized). CONCLUSIONS The reduced incidence of pH1N1 disease in older individuals shows a detailed age-specific pattern consistent with protection conferred by exposure to influenza A/H1N1 viruses circulating before 1957.The project described was supported by the National Institute Of General Medical Sciences [Award Number U54GM088558], http://www.nigms.nih. gov/. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute Of General Medical Sciences or the National Institutes of Health. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
    corecore