129 research outputs found
Spherical Hartree-Fock calculations with linear momentum projection before the variation.Part I: Energies, form factors, charge densities and mathematical sum rules
Spherical Hartree--Fock calculations with projection onto zero total linear
momentum before the variation are performed for the nuclei 4He, 12C, 16O, 28Si,
32S and 40Ca using a density--independent effective nucleon--nucleon
interaction. The results are compared to those of usual spherical Hartree--Fock
calculations subtracting the kinetic energy of the center of mass motion either
before or after the variation and to the results obtained analytically with
oscillator occupations. Total energies, hole--energies, elastic charge form
factors and charge densities and the mathematical Coulomb sum rules are
discussed.Comment: 16 pages, 13 postscript figure
Scalar Field Cosmology II: Superfluidity, Quantum Turbulence, and Inflation
We generalize the big-bang model in a previous paper by extending the real
vacuum scalar field to a complex vacuum scalar field, within the FLRW
framework. The phase dynamics of the scalar field, which makes the universe a
superfluid, is described in terms of a density of quantized vortex lines, and a
tangle of vortex lines gives rise to quantum turbulence. We propose that all
the matter in the universe was created in the turbulence, through reconnection
of vortex lines, a process necessary for the maintenance of the vortex tangle.
The vortex tangle grows and decays, and its lifetime is the era of inflation.
These ideas are implemented in a set of closed cosmological equations that
describe the cosmic expansion driven by the scalar field on the one hand, and
the vortex-matter dynamics on the other. We show how these two aspects decouple
from each other, due to a vast difference in energy scales. The model is not
valid beyond the inflation era, but the universe remains a superfluid
afterwards. This gives rise to observable effects in the present universe,
including dark matter, galactic voids, non-thermal filaments, and cosmic jets.Comment: 29 pages, 7 figures, published versio
Novel Endochin-Like Quinolones Exhibit Potent In Vitro Activity against Plasmodium knowlesi but Do Not Synergize with Proguanil.
Quinolones, such as the antimalarial atovaquone, are inhibitors of the malarial mitochondrial cytochrome bc1 complex, a target critical to the survival of both liver- and blood-stage parasites, making these drugs useful as both prophylaxis and treatment. Recently, several derivatives of endochin have been optimized to produce novel quinolones that are active in vitro and in animal models. While these quinolones exhibit potent ex vivo activity against Plasmodium falciparum and Plasmodium vivax, their activity against the zoonotic agent Plasmodium knowlesi is unknown. We screened several of these novel endochin-like quinolones (ELQs) for their activity against P. knowlesiin vitro and compared this with their activity against P. falciparum tested under identical conditions. We demonstrated that ELQs are potent against P. knowlesi (50% effective concentration, <117?nM) and equally effective against P. falciparum We then screened selected quinolones and partner drugs using a longer exposure (2.5 life cycles) and found that proguanil is 10-fold less potent against P. knowlesi than P. falciparum, while the quinolones demonstrate similar potency. Finally, we used isobologram analysis to compare combinations of the ELQs with either proguanil or atovaquone. We show that all quinolone combinations with proguanil are synergistic against P. falciparum However, against P. knowlesi, no evidence of synergy between proguanil and the quinolones was found. Importantly, the combination of the novel quinolone ELQ-300 with atovaquone was synergistic against both species. Our data identify potentially important species differences in proguanil susceptibility and in the interaction of proguanil with quinolones and support the ongoing development of novel quinolones as potent antimalarials that target multiple species
Improved tensor-product expansions for the two-particle density matrix
We present a new density-matrix functional within the recently introduced
framework for tensor-product expansions of the two-particle density matrix. It
performs well both for the homogeneous electron gas as well as atoms. For the
homogeneous electron gas, it performs significantly better than all previous
density-matrix functionals, becoming very accurate for high densities and
outperforming Hartree-Fock at metallic valence electron densities. For isolated
atoms and ions, it is on a par with previous density-matrix functionals and
generalized gradient approximations to density-functional theory. We also
present analytic results for the correlation energy in the low density limit of
the free electron gas for a broad class of such functionals.Comment: 4 pages, 2 figure
Observation of vortex formation in an oscillating trapped Bose-Einstein condensate
We report on the observation of vortex formation in a Bose-Einstein
condensate of Rb-87 atoms. Vortices are generated by superimposing an
oscillating excitation to the trapping potential introduced by an external
magnetic field. For small amplitudes of the external excitation field we
observe a bending of the cloud axis. Increasing the amplitude we observe
formation of a growing number of vortices in the sample. Shot-to-shot
variations in both vortex number and position within the condensed cloud are
observed, probably due to the intrinsic vortex nucleation dynamics. We discuss
the possible formation of vortices and anti-vortices in the sample as well as
possible mechanisms for vortex nucleation.Comment: 1 figure added, text modified, accepted for publication Phys. Rev.
The physics of dipolar bosonic quantum gases
This article reviews the recent theoretical and experimental advances in the
study of ultracold gases made of bosonic particles interacting via the
long-range, anisotropic dipole-dipole interaction, in addition to the
short-range and isotropic contact interaction usually at work in ultracold
gases. The specific properties emerging from the dipolar interaction are
emphasized, from the mean-field regime valid for dilute Bose-Einstein
condensates, to the strongly correlated regimes reached for dipolar bosons in
optical lattices.Comment: Review article, 71 pages, 35 figures, 350 references. Submitted to
Reports on Progress in Physic
Metabolic responses to the acute ingestion of two commercially available carbonated beverages: A pilot study
<p>Abstract</p> <p>Background</p> <p>The purpose of this placebo-controlled, double-blind cross-over study was to compare the effects of two commercially available soft drinks on metabolic rate.</p> <p>Methods</p> <p>After giving informed consent, twenty healthy men and women were randomly assigned to ingest 12 ounces of Celsiusâą and, on a separate day, 12 ounces of Diet CokeÂź. All subjects completed both trials using a randomized, counterbalanced design. Metabolic rate (via indirect calorimetry) and substrate oxidation (via respiratory exchange ratio) were measured at baseline (pre-ingestion) and at the end of each hour for 3 hours post-ingestion.</p> <p>Results</p> <p>Two-way ANOVA revealed a significant interaction (p < 0.001) between trials in metabolic rate. Scheffe post-hoc testing indicated that metabolic rate increased by 13.8% (+ 0.6 L/min, p < 0.001) 1 hr post, 14.4% (+0.63 L/min, p < 0.001) 2 hr post, and 8.5% (+0.37 L/min, p < 0.004) 3 hr post Celsiusâą ingestion. In contrast, small (~4â6%) but statistically insignificant increases in metabolic rate were noted following Diet Coke<sup>Âź </sup>ingestion. No differences in respiratory exchange ratio were noted between trials.</p> <p>Conclusion</p> <p>These preliminary findings indicate Celsiusâą has thermogenic properties when ingested acutely. The effects of repeated, chronic ingestion of Celsiusâą on body composition are unknown at this time.</p
Master's level in primary health care education - students' and preceptors' perceptions and experiences of the alteration in the clinical areas
Semi-synthetic analogues of cryptolepine as a potential source of sustainable drugs for the treatment of malaria, human African trypanosomiasis, and cancer
The prospect of eradicating malaria continues to be challenging in the face of increasing parasite resistance to antimalarial drugs so that novel antimalarials active against asexual, sexual, and liver-stage malaria parasites are urgently needed. In addition, new antimalarials need to be affordable and available to those most in need and, bearing in mind climate change, should ideally be sustainable. The West African climbing shrub Cryptolepis sanguinolenta is used traditionally for the treatment of malaria; its principal alkaloid, cryptolepine (1), has been shown to have antimalarial properties, and the synthetic analogue 2,7-dibromocryptolepine (2) is of interest as a lead toward new antimalarial agents. Cryptolepine (1) was isolated using a two-step Soxhlet extraction of C. sanguinolenta roots, followed by crystallization (yield 0.8% calculated as a base with respect to the dried roots). Semi-synthetic 7-bromo- (3), 7, 9-dibromo- (4), 7-iodo- (5), and 7, 9-dibromocryptolepine (6) were obtained in excellent yields by reaction of 1 with N-bromo- or N-iodosuccinimide in trifluoroacetic acid as a solvent. All compounds were active against Plasmodia in vitro, but 6 showed the most selective profile with respect to Hep G2 cells: P. falciparum (chloroquine-resistant strain K1), IC50 = 0.25 ”M, SI = 113; late stage, gametocytes, IC50 = 2.2 ”M, SI = 13; liver stage, P. berghei sporozoites IC50 = 6.13 ”M, SI = 4.6. Compounds 3â6 were also active against the emerging zoonotic species P. knowlesi with 5 being the most potent (IC50 = 0.11 ”M). In addition, 3â6 potently inhibited T. brucei in vitro at nM concentrations and good selectivity with 6 again being the most selective (IC50 = 59 nM, SI = 478). These compounds were also cytotoxic to wild-type ovarian cancer cells as well as adriamycin-resistant and, except for 5, cisplatin-resistant ovarian cancer cells. In an acute oral toxicity test in mice, 3â6 did not exhibit toxic effects at doses of up to 100 mg/kg/dose Ă 3 consecutive days. This study demonstrates that C. sanguinolenta may be utilized as a sustainable source of novel compounds that may lead to the development of novel agents for the treatment of malaria, African trypanosomiasis, and cancer.UK Medical Research Council (MRC) and a Medicines for
Malaria Venture Grant.http://www.frontiersin.org/Pharmacologyhj2022BiochemistryGeneticsMicrobiology and Plant PathologyUP Centre for Sustainable Malaria Control (UP CSMC
Measuring single cell divisions in human tissues from multi-region sequencing data.
Both normal tissue development and cancer growth are driven by a branching process of cell division and mutation accumulation that leads to intra-tissue genetic heterogeneity. However, quantifying somatic evolution in humans remains challenging. Here, we show that multi-sample genomic data from a single time point of normal and cancer tissues contains information on single-cell divisions. We present a new theoretical framework that, applied to whole-genome sequencing data of healthy tissue and cancer, allows inferring the mutation rate and the cell survival/death rate per division. On average, we found that cells accumulate 1.14 mutations per cell division in healthy haematopoiesis and 1.37 mutations per division in brain development. In both tissues, cell survival was maximal during early development. Analysis of 131 biopsies from 16 tumours showed 4 to 100 times increased mutation rates compared to healthy development and substantial inter-patient variation of cell survival/death rates
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