3,416 research outputs found
True airspeed measured by airborne laser Doppler velocimeter
Velocimeter utilizing carbon dioxide laser measures true airspeed of aircraft. Results of flight tests indicate that clear-weather airspeeds can be measured with accuracy better than 0.1% at altitudes up to 3000 meters; measurements can be made at much greater altitudes in cloudy or turbid air
The Great Reconciliation
The Great Reconciliation is truly the core and center of the entire system of Christian doctrine. All other teachings of the Bible either lead up thereto, or they proceed therefrom. Thus the doctrine of the Law and of sin shows us the need of a reconciliation. The doctrine of grace and of the redemption through Christ shows us how this reconciliation was effected. The doctrine of the means of grace and of faith teaches us how this reconciliation is made known and offered to sinners and how the individual personally apprehends the same. The doctrine of the Church shows that all those who through faith have accepted this reconciliation constitute one large body in this world, the family of God\u27s children among men. The doctrine of sanctification shows us that all those who by faith are personally reconciled to God will gratefully consecrate their lives to His service. The doctrine of the last things, finally, tells us that all who have remained faithful unto the end will enter into the full communion with their heavenly Father
Modeling pN2 through Geological Time: Implications for Planetary Climates and Atmospheric Biosignatures
Nitrogen is a major nutrient for all life on Earth and could plausibly play a
similar role in extraterrestrial biospheres. The major reservoir of nitrogen at
Earth's surface is atmospheric N2, but recent studies have proposed that the
size of this reservoir may have fluctuated significantly over the course of
Earth's history with particularly low levels in the Neoarchean - presumably as
a result of biological activity. We used a biogeochemical box model to test
which conditions are necessary to cause large swings in atmospheric N2
pressure. Parameters for our model are constrained by observations of modern
Earth and reconstructions of biomass burial and oxidative weathering in deep
time. A 1-D climate model was used to model potential effects on atmospheric
climate. In a second set of tests, we perturbed our box model to investigate
which parameters have the greatest impact on the evolution of atmospheric pN2
and consider possible implications for nitrogen cycling on other planets. Our
results suggest that (a) a high rate of biomass burial would have been needed
in the Archean to draw down atmospheric pN2 to less than half modern levels,
(b) the resulting effect on temperature could probably have been compensated by
increasing solar luminosity and a mild increase in pCO2, and (c) atmospheric
oxygenation could have initiated a stepwise pN2 rebound through oxidative
weathering. In general, life appears to be necessary for significant
atmospheric pN2 swings on Earth-like planets. Our results further support the
idea that an exoplanetary atmosphere rich in both N2 and O2 is a signature of
an oxygen-producing biosphere.Comment: 33 pages, 11 figures, 2 tables (includes appendix), published in
Astrobiolog
Transverse excitations of ultracold matter waves upon propagation past abrupt waveguide changes
The propagation of ultracold atomic gases through abruptly changing waveguide
potentials is examined in the limit of non-interacting atoms. Time-independent
scattering calculations of microstructured waveguides with discontinuous
changes in the transverse harmonic binding potentials are used to mimic
waveguide perturbations and imperfections. Three basic configurations are
examined: step-like, barrier-like and well-like with waves incident in the
ground mode. At low energies, the spectra rapidly depart from single-moded,
with significant transmission and reflection of excited modes. The high-energy
limit sees 100 percent transmission, with the distribution of the transmitted
modes determined simply by the overlap of the mode wave functions and
interference.Comment: 20 pages, 7 figures, under review PR
Magnetic behavior of EuCu2As2: Delicate balance between antiferromagnetic and ferromagnetic order
The Eu-based compound, EuCu2As2, crystallizing in the ThCr2Si2-type
tetragonal structure, has been synthesized and its magnetic behavior has been
investigated by magnetization (M), heat-capacity (C) and electrical resistivity
(rho) measurements as a function of temperature (T) and magnetic field (H) as
well as by 151Eu Moessbauer measurements. The results reveal that Eu is
divalent ordering antiferromagnetically below 15 K in the absence of magnetic
field, apparently with the formation of magnetic Brillouin-zone boundary gaps.
A fascinating observation is made in a narrow temperature range before
antiferromagnetism sets in: That is, there is a remarkable upturn just below 20
K in the plot of magnetic susceptibility versus T even at low fields, as though
the compound actually tends to order ferromagnetically. There are corresponding
anomalies in the magnetocaloric effect data as well. In addition, a small
application of magnetic field (around 1 kOe at 1.8 K) in the antiferromagnetic
state causes spin-reorientation effect. These results suggest that there is a
close balance between antiferromagnetism and ferromagnetism in this compoundComment: Phys. Rev. B, in pres
Effect of dipolar interactions on the magnetization of a cubic array of nanomagnets
We investigated the effect of intermolecular dipolar interactions on a cubic
3D ensemble of 5X5X4=100 nanomagnets, each with spin . We employed the
Landau-Lifshitz-Gilbert equation to solve for the magnetization curves
for several values of the damping constant , the induction sweep rate,
the lattice constant , the temperature , and the magnetic anisotropy
field . We find that the smaller the , the stronger the maximum
induction required to produce hysteresis. The shape of the hysteresis loops
also depends on the damping constant. We find further that the system
magnetizes and demagnetizes at decreasing magnetic field strengths with
decreasing sweep rates, resulting in smaller hysteresis loops. Variations of
within realistic values (1.5 nm - 2.5 nm) show that the dipolar interaction
plays an important role in the magnetic hysteresis by controlling the
relaxation process. The dependencies of and of are presented
and discussed with regard to recent experimental data on nanomagnets.
enhances the size of the hysteresis loops for external fields parallel to the
anisotropy axis, but decreases it for perpendicular external fields. Finally,
we reproduce and test an curve for a 2D-system [M. Kayali and W. Saslow,
Phys. Rev. B {\bf 70}, 174404 (2004)]. We show that its hysteretic behavior is
only weakly dependent on the shape anisotropy field and the sweep rate, but
depends sensitively upon the dipolar interactions. Although in 3D systems,
dipole-dipole interactions generally diminish the hysteresis, in 2D systems,
they strongly enhance it. For both square 2D and rectangular 3D lattices with
, dipole-dipole interactions can cause
large jumps in the magnetization.Comment: 15 pages 14 figures, submitted to Phys. Rev.
Repair of giant paraesophageal hernias routinely produces improvement in respiratory function
ObjectiveAssessment of the clinical impact of giant paraesophageal hernias have historically focused on upper gastrointestinal symptoms. This study assesses the effect of paraesophageal hernia repair on respiratory function.MethodsAll patients undergoing repair of giant paraesophageal hernia were prospectively entered into a database approved by the institutional review board. Patients had symptoms documented preoperatively, including dyspnea. Pulmonary function tests (PFTs) were done preoperatively and repeated a median of 106 days after repair (range, 16-660 days).ResultsPreoperative and postoperative PFTs were obtained in 120 unselected patients treated for paraesophageal hernia between 2000 and 2010. Patients’ median age was 74 years (range, 45-91 years), 74 (62%) were female, and median body mass index was 28.0 (range, 16.8-46.6). Median length of stay was 4 days (range, 3-10 days), and perioperative mortality was zero. Hernias were classified as type II in 3 (3%) patients, III in 92 (77%), and IV in 25 (21%). Percent of intrathoracic stomach was assigned from preoperative contrast studies and grouped as less than 50% (n = 6; 5%), 50% to 74% (n = 35; 29%), 75% to 99% (n = 29; 24%), and 100% (n = 50; 42%). Preoperative symptoms included heartburn 71 (59%), early satiety 65 (54%), dyspnea 63 (52%), chest pain 48 (40%), dysphagia 56 (47%), regurgitation 47 (39%), and anemia 44 (37%). PFTs significantly improved after paraesophageal hernia repair (mean volume change, percent reference change): forced vital capacity +0.30 L,+10.3%pred; FEV1 +0.23 L,+10.4%pred (all P < .001); diffusion capacity of the lung for carbon monoxide +0.58 mL · mm Hg−1 · min−1 (P = .004), and +2.9%pred (P = .002). Greater improvements were documented in older patients with significant subjective respiratory symptoms and higher percent of intrathoracic stomach (P < .01).ConclusionsParaesophageal hernia has a significant effect on respiratory function, which is largely underappreciated. This study demonstrates that these repairs can be done safely and supports routine consideration for elective repair; older patients with borderline respiratory function may achieve substantial improvements in their respiratory status and quality of life
Identification of genetic markers for productive life in commercial sows
Escalating replacement rates and production costs warrant attention on sow productive life (SPL). Increasing average SPL by one-tenth of 1 parity would result in an annual revenue increase of over $15 million in the United States. Research in model organisms has revealed conserved genes and gene pathways that lead to longer lifespan. The most prominent gene pathways are those involved in growth, most notably genes in the IGF pathway that serve to mimic the response of caloric restriction. The objective of this research was to test the hypothesis that these well conserved genes and gene pathways could also play a role in SPL, even though the productive life of sows is both a measure of longevity and their reproductive performance. Preliminary research on 3 distinct populations of over 2,000 animals suggested that several genes were associated with components of SPL. Genetic markers were then analyzed against the corresponding records of the sows for reproductive and longevity traits using a validation population of 2,000 commercial females. Right censored data were used to test associations of genetic markers with survival to defined time points. Three distinct models of survival analysis were implemented using nonparametric estimates of the survival distribution in a sequential order, using a parametric accelerated failure time model with a Weibull distribution of the error term, and a Cox proportional hazards model, which is a semiparametric model that uses an unspecified baseline hazard function. The genetic markers CCR7 and CPT1A were significantly associated (P \u3c 0.05) with survival using the nonparametric model and tended (P \u3c 0.1) toward significance using the parametric and semiparametric models with significantly different effects (P \u3c 0.05) between some genotype classes. Genetic markers for MBL2, IGFBP3, and WARS2 also tended (P \u3c 0.1) toward significance for survival traits, but were not consistent. Mixed model analyses were used to determine the associations of these genetic markers with reproductive traits. The genetic markers for IGFBP1, MBL2, CPT1A, CCR7, SLC22A5, and ACE were significantly (P \u3c 0.05) associated with at least 1 reproductive trait. These results show that molecular markers should be considered for use in marker-assisted selection to improve SPL
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