4,761 research outputs found
Total reaction cross sections from 141Pr(,)Pr elastic scattering and -induced reaction cross sections at low energies
Elastic scattering data for Pr(,)Pr have been
analyzed to derive a new energy-dependent local potential for the
Pr- system. This potential is used successfully to predict the
cross section of the Pr(,n)Pm reaction at low energies
where new experimental data have become available very recently. Contrary to
various global potentials, this new potential is able to reproduce
simultaneously elastic scattering data around and above the Coulomb barrier and
reaction data below the Coulomb barrier for the Pr- system.
Reasons for the partial failure of the global potentials are explained by
intrinsic properties of the scattering matrix and their variation with energy.
The new local potential may become the basis for the construction of a new
global -nucleus potential.Comment: 12 pages, 8 figures, Phys. Rev. C, accepte
The Roles Of Plant Hormones In Style And Stigma Growth In Gaillardia Grandiflora (Asteraceae)
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141167/1/ajb207896.pd
Quark-Novae Ia in the Hubble diagram: Implications For Dark Energy
The accelerated expansion of the Universe was proposed through the use of
Type-Ia SNe as standard candles. The standardization depends on an empirical
correlation between the stretch/color and peak luminosity of the light curves.
The use of Type Ia SN as standard candles rests on the assumption that their
properties (and this correlation) do not vary with red-shift. We consider the
possibility that the majority of Type-Ia SNe are in fact caused by a Quark-Nova
detonation in a tight neutron-star-CO-white-dwarf binary system; a Quark-Nova
Ia. The spin-down energy injected by the Quark Nova remnant (the quark star)
contributes to the post-peak light curve and neatly explains the observed
correlation between peak luminosity and light curve shape. We demonstrate that
the parameters describing Quark-Novae Ia are NOT constant in red-shift.
Simulated Quark-Nova Ia light curves provide a test of the stretch/color
correlation by comparing the true distance modulus with that determined using
SN light curve fitters. We determine a correction between the true and fitted
distance moduli which when applied to Type-Ia SNe in the Hubble diagram
recovers the Omega_M = 1 cosmology. We conclude that Type-Ia SNe observations
do not necessitate the need for an accelerating expansion of the Universe (if
the observed SNe-Ia are dominated by QNe-Ia) and by association the need for
Dark Energy.Comment: 22 pages, 6 figures. Accepted for publication in Research in
Astronomy and Astrophysic
The effect of a multispecies probiotic on the composition of the faecal microbiota and bowel habits in chronic obstructive pulmonary disease patients treated with antibiotics
Short-term antibiotic treatment profoundly affects the intestinal microbiota, which may lead to sustained changes in microbiota composition. Probiotics may restore such a disturbance. The objective of the present study was to investigate the effect of a multispecies probiotic on the faecal microbiota during and after antibiotic intake in patients with a history of frequent antibiotic use. In this randomised, placebo-controlled, double-blind study, thirty chronic obstructive pulmonary disease (COPD) patients treated with antibiotics for a respiratory tract infection received 5 g of a multispecies probiotic or placebo twice daily for 2 weeks. Faecal samples were collected at 0, 7, 14 and 63 d. Changes in the composition of the dominant faecal microbiota were determined by PCR-denaturing gradient gel electrophoresis (DGGE). Changes in bacterial subgroups were determined by quantitative PCR and culture. Bowel movements were scored daily according to the Bristol stool form scale. During and after antibiotic treatment, DGGE-based similarity indices (SI) were high ( >/= 84 %) and band richness was relatively low, both remaining stable over time. No difference in SI was observed between patients with and without diarrhoea-like bowel movements. The multispecies probiotic had a modest effect on the bacterial subgroups. Nevertheless, it affected neither the composition of the dominant faecal microbiota nor the occurrence of diarrhoea-like bowel movements. The dominant faecal microbiota was not affected by antibiotics in this COPD population, suggesting an existing imbalance of the microbiota, which may also have contributed to the lack of effect by probiotic intak
Genotypic status of the TbAT1/P2 adenosine transporter of Trypanosoma brucei gambiense isolates from northwestern Uganda following melarsoprol withdrawal
Human African trypanosomiasis (HAT) manifests as a chronic infection caused by <i>Trypanosoma brucei gambiense</i>, or as a more acute form due to <i>T. b. rhodesiense</i>. Both manifestations occur in Uganda and melarsoprol use against the former was jeopardised in the 1990s as reports of reduced efficacy increased to the point where it was dismissed as first-line treatment at some treatment centers. Previous work to elucidate possible mechanisms leading to melarsoprol resistance pointed to a P2 type adenosine transporter known to mediate melarsoprol uptake and previously shown to be mutated in significant numbers of patients not responding to the drug. Our present findings indicate that there is a low prevalence of mutants in foci where melarsoprol relapses are infrequent. In addition we observe that at the Omugo focus where the drug was withdrawn as first line over 6 years ago, the mutant alleles have disappeared, suggesting that drug pressure is responsible for fuelling their spread. Thus constant monitoring for mutants could play a key role in cost-effective HAT management by identifying which foci can still use the less logistically demanding melarsoprol as opposed to the alternative drug eflornithine. What is required now is a simple method for identifying such mutants at the point of care, enabling practitioners to make informed prescriptions at first diagnosis
High-resolution permeability determination and two-dimensional porewater flow in sandy sediment
A new, inexpensive method is proposed to measure permeability in natural sandy sediment with high spatial resolution. This methodology allows for a reconstruction of the vertical permeability anisotropy in natural sediments, with a depth resolution of a few millimeters. Thus, the possible intrusion depth of advective flow over the water-sediment interface of sandy sediments can be deduced. Shipboard measurements on five natural sandy sediment cores taken from North Sea sediments are used to demonstrate that both the direction and magnitude of the second-order permeability tensor can be calculated from direct measurements using this method. This presents a major improvement over previous methods particularly in the context of quantifying flow and reaction in permeable sediments.info:eu-repo/semantics/publishedVersio
Discussion of the results of the boundary-layer tests of an airfoil fitted with a rotary cylinder
The results of the velocity measurements in the boundary layer described in NACA-TM 411 are here discussed in greater detail. The measurements made were of the velocity distribution in the vicinity of an airfoil model fitted with a rotary cylinder and were undertaken for the purpose of obtaining a closer insight into the phenomena observed in experimenting with this model
Evaluation of the CO2 sequestration potential of afforestation projects and secondary forests in two different climate zones of South America
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