2,083 research outputs found
Physiological responses to prolonged bed rest in humans: A compendium of research, 1981-1988
Clinical observations and results form more basic studies that help to elucidate the physiological mechanisms of the adaptation of humans to prolonged bed rest. If the authors' abstract or summary was appropriate, it was included. In some cases a more detailed synopsis was provided under the subheadings of purpose, methods, results, and conclusions
Pi-K Scattering in Full QCD with Domain-Wall Valence Quarks
We calculate the pi+ K+ scattering length in fully-dynamical lattice QCD with
domain-wall valence quarks on MILC lattices with rooted staggered sea-quarks at
a lattice spacing of b=0.125 fm, lattice spatial size of L =2.5 fm and at pion
masses of m_pi=290, 350, 490 and 600 MeV. The lattice data, analyzed at
next-to-leading order in chiral perturbation theory, allows an extraction of
the full pi K scattering amplitude at threshold. Extrapolating to the physical
point gives m_pi a_3/2 = -0.0574 (+- 0.0016)(+0.0024 -0.0058) and m_pi a_1/2 =
0.1725 (+- 0.0017)(+0.0023 -0.0156) for the I=3/2 and I=1/2 scattering lengths,
respectively, where the first error is statistical and the second error is an
estimate of the systematic due to truncation of the chiral expansion.Comment: 14 pages, 9 figure
Multi-Pion Systems in Lattice QCD and the Three-Pion Interaction
The ground-state energies of 2, 3, 4 and 5 \pi^+'s in a spatial volume V (2.5
fm)^3 are computed with lattice QCD. By eliminating the leading contribution
from three-\pi^+ interactions, particular combinations of these n-\pi^+
ground-state energies provide precise extractions of the \pi^+\pi^+ scattering
length in agreement with that obtained from calculations involving only two
\pi^+'s. The three-\pi^+ interaction can be isolated by forming other
combinations of the n-\pi^+ ground-state energies. We find a result that is
consistent with a repulsive three-\pi^+ interaction for m_\pi < 352 MeV.Comment: 4 pages, 5 figure
Perturbative Effective Theory in an Oscillator Basis?
The effective interaction/operator problem in nuclear physics is believed to
be highly nonperturbative, requiring extended high-momentum spaces for accurate
solution. We trace this to difficulties that arise at both short and long
distances when the included space is defined in terms of a basis of harmonic
oscillator Slater determinants. We show, in the simplest case of the deuteron,
that both difficulties can be circumvented, yielding highly perturbative
results in the potential even for modest (~6hw) included spaces.Comment: 10 pages, 4 figure
High Statistics Analysis using Anisotropic Clover Lattices: (I) Single Hadron Correlation Functions
We present the results of high-statistics calculations of correlation
functions generated with single-baryon interpolating operators on an ensemble
of dynamical anisotropic gauge-field configurations generated by the Hadron
Spectrum Collaboration using a tadpole-improved clover fermion action and
Symanzik-improved gauge action. A total of 292,500 sets of measurements are
made using 1194 gauge configurations of size 20^3 x 128 with an anisotropy
parameter \xi= b_s/b_t = 3.5, a spatial lattice spacing of b_s=0.1227\pm 0.0008
fm, and pion mass of m_\pi ~ 390 MeV. Ground state baryon masses are extracted
with fully quantified uncertainties that are at or below the ~0.2%-level in
lattice units. The lowest-lying negative-parity states are also extracted
albeit with a somewhat lower level of precision. In the case of the nucleon,
this negative-parity state is above the N\pi threshold and, therefore, the
isospin-1/2 \pi N s-wave scattering phase-shift can be extracted using
Luescher's method. The disconnected contributions to this process are included
indirectly in the gauge-field configurations and do not require additional
calculations. The signal-to-noise ratio in the various correlation functions is
explored and is found to degrade exponentially faster than naive expectations
on many time-slices. This is due to backward propagating states arising from
the anti-periodic boundary conditions imposed on the quark-propagators in the
time-direction. We explore how best to distribute computational resources
between configuration generation and propagator measurements in order to
optimize the extraction of single baryon observables
The K+K+ Scattering Length from Lattice QCD
The K+K+ scattering length is calculated in fully-dynamical lattice QCD with
domain-wall valence quarks on the MILC asqtad-improved gauge configurations
with rooted staggered sea quarks. Three-flavor mixed-action chiral perturbation
theory at next-to-leading order, which includes the leading effects of the
finite lattice spacing, is used to extrapolate the results of the lattice
calculation to the physical value of m_{K+}/f_{K+}. We find m_{K+} a_{K+K+} =
-0.352 +- 0.016, where the statistical and systematic errors have been combined
in quadrature.Comment: 17 pages, 12 figures. NPLQCD collaboratio
Precise Determination of the I=2 pipi Scattering Length from Mixed-Action Lattice QCD
The I=2 pipi scattering length is calculated in fully-dynamical lattice QCD
with domain-wall valence quarks on the asqtad-improved coarse MILC
configurations (with fourth-rooted staggered sea quarks) at four light-quark
masses. Two- and three-flavor mixed-action chiral perturbation theory at
next-to-leading order is used to perform the chiral and continuum
extrapolations. At the physical charged pion mass, we find m_pi a_pipi(I=2) =
-0.04330 +- 0.00042, where the error bar combines the statistical and
systematic uncertainties in quadrature.Comment: 20 pages, 7 figure
Development and comparison of novel multiple cross displacement amplification (MCDA) assays with other nucleic acid amplification methods for SARS-CoV-2 detection
The development of alternative isothermal amplification assays including multiple cross displacement amplification (MCDA) may address speed and portability limitations of real-time PCR (rt-PCR) methods for SARS-CoV-2 detection. We developed a novel SARS-CoV-2 MCDA assay and compared its speed and sensitivity to loop-mediated isothermal amplification (LAMP) and rt-PCR. Two MCDA assays targeting SARS-CoV-2 N gene and ORF1ab were designed. The fastest time to detection and sensitivity of MCDA was compared to LAMP and rt-PCR using DNA standards and transcribed RNA. For the N gene, MCDA was faster than LAMP and rt-PCR by 10 and 20 min, respectively with fastest time to detection at 5.2 min. rt-PCR had the highest sensitivity with the limit of detection at 10 copies/µl compared with MCDA (100 copies/µl) and LAMP (500 copies/µl). For ORF1ab, MCDA and LAMP had similar speed with fastest time to detection at 9.7 and 8.4 min, respectively. LAMP was more sensitive for ORF1ab detection with 50 copies/µl compared to MCDA (500 copies/µl). In conclusion, different nucleic acid amplification methods provide different advantages. MCDA is the fastest nucleic acid amplification method for SARS-CoV-2 while rt-PCR is the most sensitive. These advantages should be considered when determining the most suitable nucleic acid amplification methods for different applications
Comparative Phosphoproteomics of Classical Bordetellae Elucidates the Potential Role of Serine, Threonine and Tyrosine Phosphorylation in Bordetella Biology and Virulence.
The Bordetella genus is divided into two groups: classical and non-classical. Bordetella pertussis, Bordetella bronchiseptica and Bordetella parapertussis are known as classical bordetellae, a group of important human pathogens causing whooping cough or whooping cough-like disease and hypothesized to have evolved from environmental non-classical bordetellae. Bordetella infections have increased globally driving the need to better understand these pathogens for the development of new treatments and vaccines. One unexplored component in Bordetella is the role of serine, threonine and tyrosine phosphorylation. Therefore, this study characterized the phosphoproteome of classical bordetellae and examined its potential role in Bordetella biology and virulence. Applying strict identification of localization criteria, this study identified 70 unique phosphorylated proteins in the classical bordetellae group with a high degree of conservation. Phosphorylation was a key regulator of Bordetella metabolism with proteins involved in gluconeogenesis, TCA cycle, amino acid and nucleotide synthesis significantly enriched. Three key virulence pathways were also phosphorylated including type III secretion system, alcaligin synthesis and the BvgAS master transcriptional regulatory system for virulence genes in Bordetella. Seven new phosphosites were identified in BvgA with 6 located in the DNA binding domain. Of the 7, 4 were not present in non-classical bordetellae. This suggests that serine/threonine phosphorylation may play an important role in stabilizing/destabilizing BvgA binding to DNA for fine-tuning of virulence gene expression and that BvgA phosphorylation may be an important factor separating classical from non-classical bordetellae. This study provides the first insight into the phosphoproteome of classical Bordetella species and the role that Ser/Thr/Tyr phosphorylation may play in Bordetella biology and virulence
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Loss of testosterone impairs anti-tumor neutrophil function.
In men, the incidence of melanoma rises rapidly after age 50, and nearly two thirds of melanoma deaths are male. The immune system is known to play a key role in controlling the growth and spread of malignancies, but whether age- and sex-dependent changes in immune cell function account for this effect remains unknown. Here, we show that in castrated male mice, neutrophil maturation and function are impaired, leading to elevated metastatic burden in two models of melanoma. Replacement of testosterone effectively normalized the tumor burden in castrated male mice. Further, the aberrant neutrophil phenotype was also observed in prostate cancer patients receiving androgen deprivation therapy, highlighting the evolutionary conservation and clinical relevance of the phenotype. Taken together, these results provide a better understanding of the role of androgen signaling in neutrophil function and the impact of this biology on immune control of malignancies
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