3,302 research outputs found
Classical-quantum correspondence in bosonic two-mode conversion systems: polynomial algebras and Kummer shapes
Bosonic quantum conversion systems can be modeled by many-particle
single-mode Hamiltonians describing a conversion of molecules of type A
into molecules of type B and vice versa. These Hamiltonians are analyzed in
terms of generators of a polynomially deformed algebra. In the
mean-field limit of large particle numbers, these systems become classical and
their Hamiltonian dynamics can again be described by polynomial deformations of
a Lie algebra, where quantum commutators are replaced by Poisson brackets. The
Casimir operator restricts the motion to Kummer shapes, deformed Bloch spheres
with cusp singularities depending on and . It is demonstrated that the
many-particle eigenvalues can be recovered from the mean-field dynamics using a
WKB type quantization condition. The many-particle state densities can be
semiclassically approximated by the time-periods of periodic orbits, which show
characteristic steps and singularities related to the fixed points, whose
bifurcation properties are analyzed.Comment: 13 pages, 13 figure
Quasiclassical analysis of Bloch oscillations in non-Hermitian tight-binding lattices
Many features of Bloch oscillations in one-dimensional quantum lattices with
a static force can be described by quasiclassical considerations for example by
means of the acceleration theorem, at least for Hermitian systems. Here the
quasiclassical approach is extended to non-Hermitian lattices, which are of
increasing interest. The analysis is based on a generalised non-Hermitian phase
space dynamics developed recently. Applications to a single-band tight-binding
system demonstrate that many features of the quantum dynamics can be understood
from this classical description qualitatively and even quantitatively. Two
non-Hermitian and -symmetric examples are studied, a Hatano-Nelson lattice
with real coupling constants and a system with purely imaginary couplings, both
for initially localised states in space or in momentum. It is shown that the
time-evolution of the norm of the wave packet and the expectation values of
position and momentum can be described in a classical picture.Comment: 20 pages, 8 figures, typos corrected, slightly extended, accepted for
publication in New Journal of Physics in Focus Issue on Parity-Time Symmetry
in Optics and Photonic
A Global Hypothesis for Women in Journalism and Mass Communications: The Ratio of Recurrent and Reinforced Residuum
This paper examines the status of women in communications industries and on university faculties. It specifically tests the Ratio of Recurrent and Reinforced Residuum or R3 hypothesis, as developed by Rush in the early 1980s [Rush, Buck & Ogan,1982]. The R3 hypothesis predicts that the percentage of women in the communications industries and on university faculties will follow the ratio residing around 1/4:3/4 or 1/3:2/3 proportion females to males. This paper presents data from a nationwide U.S. survey and compares them to data from global surveys and United Nations reports. The evidence is overwhelming and shows the relevance and validity of the R3 hypothesis across different socio-economic and cultural contexts. The paper argues that the ratio is the outcome of systemic discrimination that operates at multiple levels. The obstacles to achieving equality in the academy as well as media industries are discussed and suggestions for breaking out of the R3 ratio are included.
A Global Hypothesis for Women in Journalism and Mass Communications: The Ratio of Recurrent and Reinforced Residuum
This paper examines the status of women in communications industries and on university faculties. It specifically tests the Ratio of Recurrent and Reinforced Residuum or R3 hypothesis, as developed by Rush in the early 1980s [Rush, Buck & Ogan,1982]. The R3 hypothesis predicts that the percentage of women in the communications industries and on university faculties will follow the ratio residing around 1/4:3/4 or 1/3:2/3 proportion females to males. This paper presents data from a nationwide U.S. survey and compares them to data from global surveys and United Nations reports. The evidence is overwhelming and shows the relevance and validity of the R3 hypothesis across different socio-economic and cultural contexts. The paper argues that the ratio is the outcome of systemic discrimination that operates at multiple levels. The obstacles to achieving equality in the academy as well as media industries are discussed and suggestions for breaking out of the R3 ratio are included.
Stability of Glutamate-Aspartate Cardioplegia Additive Solution in Polyolefin IV Bags
Objective: Glutamate-aspartate cardioplegia additive solution (GACAS) is used to enhance myocardial preservation and left ventricular function during some cardiac surgeries. This study was designed to evaluate the stability of compounded GACAS stored in sterile polyolefin intravenous (IV) bags. The goal is to extend the default USP beyond-use date (BUD) and reduce unnecessary inventory waste.
Methods: GACAS was compounded and packaged in sterile polyolefin 250 mL IV bags. The concentration was 232 mM for each amino acid. The samples were stored under refrigeration (2°C-8°C) and analyzed at 0, 1, and 2 months. At each time point, the samples were evaluated by pH measurement and visual inspection for color, clarity, and particulates. The samples were also analyzed by high-performance liquid chromatography (HPLC) for potency and degradation products. Due to the lack of ultraviolet (UV) chromophores of glutamate and aspartate, the samples were derivatized by ortho-phthalaldehyde prior to HPLC analysis.
Results: The time zero samples of GACAS passed the physical, chemical, and microbiological tests. Over 2 months of storage, there was no significant change in pH or visual appearance for any of the stability samples. The HPLC results also indicated that the samples retained 101% to 103% of the label claim strengths for both amino acids.
Conclusion: The physical and chemical stability of extemporaneously prepared GACAS has been confirmed for up to 2 months in polyolefin IV bags stored under refrigeration. With proper sterile compounding practice and microbiology testing, the BUD of this product can be extended to 2 months
An Analysis of Archival Observations Made of Galactic Supernova Remnants by the Chandra X-ray Observatory
Since its launch in 1999, the Chandra X-ray Observatory has spurred explosive growth in the study of Galactic supernova remnants (SNRs) due to its unsurpassed angular resolution (1 arcsecond at 1 keV) and its moderate sensitivity. We are currently analyzing archival observations made by Chandra of two particular classes of SNRs: mixed-morphology SNRs (which feature contrasting center-filled thermal X-ray morphologies with shell-like radio morphologies) and synchrotron X-ray SNRs (which feature X-ray spectra dominated by synchrotron emission). To illustrate some of our initial results, we present spatially resolved spectroscopic analyses of the mixed-morphology SNR 3C 397 and the synchrotron X-ray dominated SNR G353.6-0.7. In the former case, we have fit extracted spectra with a recombination-dominated thermal plasma model to determine the ionization state of the plasma associated with this SNR. In the latter case, we have fit extracted spectra with synchrotron models to determine the maximum energies of cosmic-ray electrons accelerated by the SNR
Recommended from our members
Feline Hypertrophic Cardiomyopathy: A Spontaneous Large Animal Model of Human HCM.
Hypertrophic cardiomyopathy (HCM) is a common disease in pet cats, affecting 10-15% of the pet cat population. The similarity to human HCM, the rapid progression of disease, and the defined and readily determined endpoints of feline HCM make it an excellent natural model that is genotypically and phenotypically similar to human HCM. The Maine Coon and Ragdoll cats are particularly valuable models of HCM because of myosin binding protein-C mutations and even higher disease incidence compared to the overall feline population. The cat overcomes many of the limitations of rodent HCM models, and can provide enhanced translation of information from in vitro and induced small animal models to human clinical trials. Physicians and veterinarians working together in a collaborative and interdisciplinary approach can accelerate the discovery of more effective treatments for this and other cardiovascular diseases affecting human and veterinary patients
Differentiation of Cardiac from Noncardiac Pleural Effusions in Cats using Second-Generation Quantitative and Point-of-Care NT-proBNP Measurements
BACKGROUND: Pleural effusion is a common cause of dyspnea in cats. Nâterminal proâBâtype natriuretic peptide (NTâproBNP) measurement, using a firstâgeneration quantitative ELISA, in plasma and pleural fluid differentiates cardiac from noncardiac causes of pleural effusion. HYPOTHESIS/OBJECTIVES: To determine whether NTâproBNP measurements using secondâgeneration quantitative ELISA and pointâofâcare (POC) tests in plasma and pleural fluid distinguish cardiac from noncardiac pleural effusions and how results compare to the firstâgeneration ELISA. ANIMALS: Thirtyâeight cats (US cohort) and 40 cats (UK cohort) presenting with cardiogenic or noncardiogenic pleural effusion. METHODS: Prospective cohort study. Twentyâone and 17 cats in the US cohort, and 22 and 18 cats in the UK cohort were classified as having cardiac or noncardiac pleural effusion, respectively. NTâproBNP concentrations in paired plasma and pleural fluid samples were measured using secondâgeneration ELISA and POC assays. RESULTS: The secondâgeneration ELISA differentiated cardiac from noncardiac pleural effusion with good diagnostic accuracy (plasma: sensitivity, 95.2%, specificity, 82.4%; pleural fluid: sensitivity, 100%, specificity, 76.5%). NTâproBNP concentrations were greater in pleural fluid (719 pmol/L (134â1500)) than plasma (678 pmol/L (61â1500), P = 0.003), resulting in different cutâoff values depending on the sample type. The POC test had good sensitivity (95.2%) and specificity (87.5%) when using plasma samples. In pleural fluid samples, the POC test had good sensitivity (100%) but low specificity (64.7%). Diagnostic accuracy was similar between firstâ and secondâgeneration ELISA assays. CONCLUSIONS AND CLINICAL IMPORTANCE: Measurement of NTâproBNP using a quantitative ELISA in plasma and pleural fluid or POC test in plasma, but not pleural fluid, distinguishes cardiac from noncardiac causes of pleural effusion in cats
Pharmacometabolomic mapping of early biochemical changes induced by sertraline and placebo.
In this study, we characterized early biochemical changes associated with sertraline and placebo administration and changes associated with a reduction in depressive symptoms in patients with major depressive disorder (MDD). MDD patients received sertraline or placebo in a double-blind 4-week trial; baseline, 1 week, and 4 weeks serum samples were profiled using a gas chromatography time of flight mass spectrometry metabolomics platform. Intermediates of TCA and urea cycles, fatty acids and intermediates of lipid biosynthesis, amino acids, sugars and gut-derived metabolites were changed after 1 and 4 weeks of treatment. Some of the changes were common to the sertraline- and placebo-treated groups. Changes after 4 weeks of treatment in both groups were more extensive. Pathway analysis in the sertraline group suggested an effect of drug on ABC and solute transporters, fatty acid receptors and transporters, G signaling molecules and regulation of lipid metabolism. Correlation between biochemical changes and treatment outcomes in the sertraline group suggested a strong association with changes in levels of branched chain amino acids (BCAAs), lower BCAAs levels correlated with better treatment outcomes; pathway analysis in this group revealed that methionine and tyrosine correlated with BCAAs. Lower levels of lactic acid, higher levels of TCA/urea cycle intermediates, and 3-hydroxybutanoic acid correlated with better treatment outcomes in placebo group. Results of this study indicate that biochemical changes induced by drug continue to evolve over 4 weeks of treatment and that might explain partially delayed response. Response to drug and response to placebo share common pathways but some pathways are more affected by drug treatment. BCAAs seem to be implicated in mechanisms of recovery from a depressed state following sertraline treatment
Fall-related injury in the hospital
Background: 2 â 9% of adult patients who fall in the hospital suffer serious injury. There is little evidence-based literature to guide physicians when assessing hospitalized patients for fall-related injury. This study was designed to (1) identify demographic and/or clinical factors which predict serious fall-related injury among hospitalized adults, and (2) judge the adequacy of physician documentation related to adult patients who fell in the hospital. Methods: Nursing staff are required to report all hospital falls through our hospitals computerized Patient Safety Network (PSN). We performed a retrospective chart review of all PSN reported falls that occurred during 2010 in our 431-bed university acute care hospital. Patients less than18 years old, pregnant women, and prisoners were excluded. Results: Medical records were available for 286/293 (98%) of PSN-reported falls in 251 eligible patients. Falls occurred in 152 males (61%), and 99 females (39%). 48% of falls occurred while toileting. 25% (63/286) of falls were associated with injury, and 4% (11/286) with serious injury (laceration requiring closure or fracture). Compared to all fallers, patients with injury did not differ by gender (males 38/152 vs. females 25/99, p=0.96). Patients older than 64 years who fell were no more likely to suffer injury that younger adults (13/64 vs. 50/187, p = 0.31). In univariate analysis, patients who reported hitting their head, patients with pre-fall confusion, and patients who received narcotics on the day of fall were more likely to suffer injury (estimated odds ratios 6.04, 2.00 and 5.1, respectfully). In multivariate analysis, receiving a narcotic on the day of fall was the strongest predictor of injury (Table). 33% (21/63) of falls with injury had no physician documentation in the hospital record, and in only 21% (13/63) of cases, were falls with injury mentioned in the discharge summary. Conclusions: In this single-institution study, injury occurred in 25% of patients who fell, and serious injury in 4%. Compared to all falls, falls with injury did not vary by gender or age. Receiving a narcotic of the day of fall was the strongest predictor of injury. Physicians inconsistently provided medical record documentation of hospitalized patients who fell with injury.\u2
- âŠ