1,473 research outputs found
Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars
We report the results for rotational velocities, Vrot sin i, and macroturbulence dispersions, ζRT, for 12 metal-poor field red giant branch (RGB) stars and 7 metal-poor field red horizontal branch (RHB) stars. The results are based on Fourier transform
Chloroplast two-component systems: evolution of the link between photosynthesis and gene expression
Two-component signal transduction, consisting of sensor kinases and response regulators, is the predominant signalling mechanism in bacteria. This signalling system originated in prokaryotes and has spread throughout the eukaryotic domain of life through endosymbiotic, lateral gene transfer from the bacterial ancestors and early evolutionary precursors of eukaryotic, cytoplasmic, bioenergetic organelles—chloroplasts and mitochondria. Until recently, it was thought that two-component systems inherited from an ancestral cyanobacterial symbiont are no longer present in chloroplasts. Recent research now shows that two-component systems have survived in chloroplasts as products of both chloroplast and nuclear genes. Comparative genomic analysis of photosynthetic eukaryotes shows a lineage-specific distribution of chloroplast two-component systems. The components and the systems they comprise have homologues in extant cyanobacterial lineages, indicating their ancient cyanobacterial origin. Sequence and functional characteristics of chloroplast two-component systems point to their fundamental role in linking photosynthesis with gene expression. We propose that two-component systems provide a coupling between photosynthesis and gene expression that serves to retain genes in chloroplasts, thus providing the basis of cytoplasmic, non-Mendelian inheritance of plastid-associated characters. We discuss the role of this coupling in the chronobiology of cells and in the dialogue between nuclear and cytoplasmic genetic systems
The perseverance of Pacioli's goods inventory accounting system
This paper details sources of the 'undoubtedly strange' (Yamey, 1994a, p.119) system of goods inventory records described in Pacioli’s 1494 bookkeeping treatise and traces the longevity and widespread use of this early perpetual inventory recording (EPIR) system in English language texts. By doing so and contrasting this system with the bookkeeping treatment of modern texts, it is shown that the EPIR system persisted as the dominant form of goods inventory accounting for between 400 and 500 years and that the reasons for its demise are worthy of further consideration and research
Adiabatic following criterion, estimation of the nonadiabatic excitation fraction and quantum jumps
An accurate theory describing adiabatic following of the dark, nonabsorbing
state in the three-level system is developed. An analytical solution for the
wave function of the particle experiencing Raman excitation is found as an
expansion in terms of the time varying nonadiabatic perturbation parameter. The
solution can be presented as a sum of adiabatic and nonadiabatic parts. Both
are estimated quantitatively. It is shown that the limiting value to which the
amplitude of the nonadiabatic part tends is equal to the Fourier component of
the nonadiabatic perturbation parameter taken at the Rabi frequency of the
Raman excitation. The time scale of the variation of both parts is found. While
the adiabatic part of the solution varies slowly and follows the change of the
nonadiabatic perturbation parameter, the nonadiabatic part appears almost
instantly, revealing a jumpwise transition between the dark and bright states.
This jump happens when the nonadiabatic perturbation parameter takes its
maximum value.Comment: 33 pages, 8 figures, submitted to PRA on 28 Oct. 200
Species-specific kinetics and zonation of hepatic DNA synthesis induced by ligands of PPAR?
PPAR? ligands evoke a profound mitogenic response in rodent liver, and the aim of this studywas to characterise the kinetics of induction of DNA synthesis. The CAR ligand, 1,4-bis[2-(3,5-dichoropyridyloxy)]benzene, caused induction of hepatocyte DNA synthesis within 48 hours in129S4/SvJae mice, but the potent PPAR? ligand, ciprofibrate, induced hepatocyte DNA synthesisonly after 3 or 4 days dosing; higher or lower doses did not hasten the DNA synthesisresponse. This contrasted with the rapid induction (24 hours) reported by Styles et al. (Carcinogenesis9:1647-1655). C57BL/6 and DBA/2J mice showed significant induction of DNA synthesisafter 4, but not 2, days ciprofibrate treatment. Alderley Park and 129S4/SvJae mice dosedwith methylclofenapate induced hepatocyte DNA synthesis at 4, but not 2, days after dosing,and proved that inconsistency with prior work was not due to a difference in mouse strain orPPAR? ligand. Ciprofibrate-induced liver DNA synthesis and growth was absent in PPAR?-null mice, and are PPAR?-dependent. In the Fisher344 rat, hepatocyte DNA synthesis was inducedat 24 hours after dosing, with a second peak at 48 hours. Lobular localisation of hepatocyteDNA synthesis showed preferential periportal induction of DNA synthesis in rat, butpanlobular zonation of hepatocyte DNA synthesis in mouse. These results characterise a markedlylater hepatic induction of panlobular DNA synthesis by PPAR? ligands in mouse, comparedto rapid induction of periportal DNA synthesis in rat
Meson screening masses from lattice QCD with two light and the strange quark
We present results for screening masses of mesons built from light and
strange quarks in the temperature range of approximately between 140 MeV to 800
MeV. The lattice computations were performed with 2+1 dynamical light and
strange flavors of improved (p4) staggered fermions along a line of constant
physics defined by a pion mass of about 220 MeV and a kaon mass of 500 MeV. The
lattices had temporal extents Nt = 4, 6 and 8 and aspect ratios of Ns / Nt \geq
4. At least up to a temperature of 140 MeV the pseudo-scalar screening mass
remains almost equal to the corresponding zero temperature pseudo-scalar (pole)
mass. At temperatures around 3Tc (Tc being the transition temperature) the
continuum extrapolated pseudo-scalar screening mass approaches very close to
the free continuum result of 2 \pi T from below. On the other hand, at high
temperatures the vector screening mass turns out to be larger than the free
continuum value of 2 \pi T. The pseudo-scalar and the vector screening masses
do not become degenerate even for a temperature as high as 4Tc. Using these
mesonic spatial correlation functions we have also investigated the restoration
of chiral symmetry and the effective restoration of the axial symmetry. We have
found that the vector and the axial-vector screening correlators become
degenerate, indicating chiral symmetry restoration, at a temperature which is
consistent with the QCD transition temperature obtained in previous studies. On
the other hand, the pseudo-scalar and the scalar screening correlators become
degenerate only at temperatures larger than 1.3Tc, indicating that the
effective restoration of the axial symmetry takes place at a temperature larger
than the QCD transition temperature.Comment: Published versio
Longitudinal medical resources and costs among type 2 diabetes patients participating in the Trial Evaluating Cardiovascular Outcomes with Sitagliptin (TECOS)
Aims: TECOS, a cardiovascular safety trial (ClinicalTrials.gov identifier: NCT00790205) involving 14 671 patients with type 2 diabetes and cardiovascular disease, demonstrated that sitagliptin was non-inferior to placebo for the primary composite cardiovascular outcome when added to best usual care. This study tested hypotheses that medical resource use and costs differed between these 2 treatment strategies. Materials and methods: Information concerning medical resource use was collected on case report forms throughout the trial and was valued using US costs for: Medicare payments for hospitalizations, medical procedures and outpatient visits, and wholesale acquisition costs (WAC) for diabetes-related medications. Hierarchical generalized linear models were used to compare resource use and US costs, accounting for variable intercountry practice patterns. Sensitivity analyses included resource valuation using English costs for a UK perspective. Results: There were no significant differences in hospitalizations, inpatient days, medical procedures, or outpatient visits during follow-up (mean and median 3.0 years in both groups). Hospitalization rates appeared to diverge after 2 years, with lower rates among sitagliptin-treated vs placebo patients after 2.5 years (relative rate, 0.90 [95% CI, 0.83-0.97]; P =.01). Mean medical costs, exclusive of study medication, were 11 937 USD in the sitagliptin arm and 12 409 USD in the placebo arm (P =.06). Mean sitagliptin costs based on undiscounted WAC were 9978 USD per patient. Differential UK total costs including study drug costs were smaller (911 GBP), primarily because of lower mean costs for sitagliptin (1072 GBP). Conclusions: Lower hospitalization rates across time with sitagliptin slightly offset sitagliptin treatment costs over 3 years in type 2 diabetes patients at high risk for cardiovascular events
Momentum-resolved electronic structure at a buried interface from soft x-ray standing-wave angle-resolved photoemission
Angle-resolved photoemission spectroscopy (ARPES) is a powerful technique for
the study of electronic structure, but it lacks a direct ability to study
buried interfaces between two materials. We address this limitation by
combining ARPES with soft x-ray standing-wave (SW) excitation (SWARPES), in
which the SW profile is scanned through the depth of the sample. We have
studied the buried interface in a prototypical magnetic tunnel junction
La0.7Sr0.3MnO3/SrTiO3. Depth- and momentum-resolved maps of Mn 3d eg and t2g
states from the central, bulk-like and interface-like regions of La0.7Sr0.3MnO3
exhibit distinctly different behavior consistent with a change in the Mn
bonding at the interface. We compare the experimental results to
state-of-the-art density-functional and one-step photoemission theory, with
encouraging agreement that suggests wide future applications of this technique.Comment: 18 pages, 4 figures and Supplementary Informatio
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A high repetition rate beam profile monitor
A high repetition rate beam profile monitor is needed to measure the momentum distribution of each bunch in a 200 bunch train at the Brookhaven Accelerator Test Facility. We have designed a monitor using secondary emission from a microstrip delay line. The delay line converts position information into discrete time delays synchronous with the sampling rate of a fast transient digitizer. We present the results of initial electrical testing here
Health-related quality of life in people with type 2 diabetes participating in the LEADER trial
Aims: To assess health-related quality of life (HRQoL) in people with type 2 diabetes (T2D) participating in the LEADER cardiovascular outcomes trial using the five-dimension European Quality of Life questionnaire (EQ-5D). Materials and methods: The EQ-5D was administered every 12 months in a subset of patients from Canada, Denmark, Germany, Ireland, Italy, Netherlands, Spain, Sweden, the United Kingdom and the United States. We compared changes in utility index scores and visual analogue scale (VAS) scores from baseline to 36 months in participants treated with liraglutide and placebo. We also assessed which complications had the greatest impact on quality of life. Results: At 36 months, less deterioration in EQ-5D utility index score was seen in the liraglutide group (−0.058) than in the placebo group (−0.082; estimated treatment difference [ETD] 0.023, 95% confidence interval [CI] 0.004;0.043; P = 0.020). A smaller decrease in EQ-5D VAS score was also demonstrated in the liraglutide group (−3.51) vs. the placebo group (−5.45; ETD 1.94, 95% CI 0.32;3.57; P = 0.019). The benefits of liraglutide treatment compared with placebo were driven primarily by shifts in the domains of mobility and self-care. The most influential events contributing to poorer HRQoL were stroke, heart failure, malignant neoplasm and confirmed hypoglycaemia. Conclusions: Liraglutide demonstrated a modest but significant benefit in patient-reported health status using the EQ-5D, compared with placebo. This benefit may be of clinical relevance and requires further study
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