683 research outputs found
Hydroclimatic changes in the British Isles through the Last-Glacial-Interglacial Transition:Multiproxy reconstructions from the Vale of Pickering, NE England
European paleoenvironmental records through the Last Glacial-Interglacial Transition (LGIT; ca 16-8 cal ka BP) record a series of climatic events occurring over decadal to multi-centennial timescales. Changes in components of the climatic system other than temperature (e.g. hydrology) through the LGIT are relatively poorly understood however, and further records of hydroclimatic changes are required in order to develop a more complete understanding on the phasing of environmental and anthropogenic responses in Europe to abrupt climate change. Here, we present a multiproxy palaeoenvironmental record (macroscale and microscale sedimentology, macrofossils, and carbonate stable isotopes) from a palaeolake sequence in the Vale of Pickering (VoP), NE England, which enables the reconstruction of hydroclimatic changes constrained by a radiocarbon-based chronology. Relative lake-level changes in the VoP occurred in close association (although not necessarily in phase) to threshold shifts across abrupt climate change transitions, most notably lowering during cooling intervals of the LGIT (âźGI-1d, âźGI-1b, and âźGS-1). This reflects more arid hydroclimates associated with these cooling episodes in the British Isles. Comparisons to hydrological records elsewhere in Europe show a latitudinal bifurcation, with Northern Europe (50â60°N) becoming more arid (humid), and Southern Europe (40â50°N) becoming more humid (arid) in response to these cooling (warming) intervals. We attribute these bifurcating signals to the relative positions of the Atlantic storm tracks, sea-ice margin, and North Atlantic Polar Front (NAPF) during the climatic events of the LGIT
Specific refolding pathway of viscumin A chain in membrane-like medium reveals a possible mechanism of toxin entry into cell
How is a water-soluble globular protein able to spontaneously cross a cellular membrane? It is commonly accepted that it undergoes significant structural rearrangements on the lipid-water interface, thus acquiring membrane binding and penetration ability. In this study molecular dynamics (MD) simulations have been used to explore large-scale conformational changes of the globular viscumin A chain in a complex environment - comprising urea and chloroform/methanol (CHCl /MeOH) mixture. Being well-packed in aqueous solution, viscumin A undergoes global structural rearrangements in both organic media. In urea, the protein is "swelling" and gradually loses its long-distance contacts, thus resembling the "molten globule" state. In CHCl /MeOH, viscumin A is in effect turned "inside out". This is accompanied with strengthening of the secondary structure and surface exposure of hydrophobic epitopes originally buried inside the globule. Resulting solvent-adapted models were further subjected to Monte Carlo simulations with an implicit hydrophobic slab membrane. In contrast to only a few point surface contacts in water and two short regions with weak protein-lipid interactions in urea, MD-derived structures in CHCl /MeOH reveal multiple determinants of membrane interaction. Consequently it is now possible to propose a specific pathway for the structural adaptation of viscumin A with respect to the cell membrane - a probable first step of its translocation into cytoplasmic targets
Dynamical properties of liquid Al near melting. An orbital-free molecular dynamics study
The static and dynamic structure of liquid Al is studied using the orbital
free ab-initio molecular dynamics method. Two thermodynamic states along the
coexistence line are considered, namely T = 943 K and 1323 K for which X-ray
and neutron scattering data are available. A new kinetic energy functional,
which fulfills a number of physically relevant conditions is employed, along
with a local first principles pseudopotential. In addition to a comparison with
experiment, we also compare our ab-initio results with those obtained from
conventional molecular dynamics simulations using effective interionic pair
potentials derived from second order pseudopotential perturbation theory.Comment: 15 pages, 12 figures, 2 tables, submitted to PR
Tomato: a crop species amenable to improvement by cellular and molecular methods
Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures.
In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.
A gene variant near ATM is significantly associated with metformin treatment response In type 2 diabetes: A replication and meta-analysis of five cohorts
_Aims/hypothesis:_ In this study we aimed to replicate the previously reported association between the glycaemic response to metformin and the SNP rs11212617 at a locus that includes the ataxia telangiectasia mutated (ATM) gene in multiple additional populations.
_Methods:_ Incident users of metformin selected from the Diabetes Care System West-Friesland (DCS, n=929) and the Rotterdam Study (n=182) from the Netherlands, and the CARDS Trial (n=254) from the UK were genotyped for rs11212617 and tested for an association with both HbA1c reduction and treatment success, defined as the ability to reach the treatment target of an HbA1c â¤7 % (53 mmol/mol). Finally, a meta-analysis including data from literature was performed.
_Results:_ In the DCS cohort, we observed an association between rs11212617 genotype and treatment success on metformin (OR 1.27, 95% CI 1.03, 1.58, p=0.028); in the smaller Rotterdam Study cohort, a numerically similar but non-significant trend was observed (OR 1.45, 95% CI 0.87, 2.39, p=0.15); while in the CARDS cohort there was no significant association. In meta-analyses of these three cohorts separately or combined with the previously published cohorts, rs11212617 genotype is associated with metformin treatment success (OR 1.24, 95% CI 1.04, 1.49, p=0.016 and OR 1.25, 95% CI 1.33, 1.38, p=7.8Ă10-6, respectively).
_ Conclusions/inte
Schottky levels and thermodynamic contributions of light lanthanide sesquisulfides having the Th3P4 structure
Heat capacity measurements were made by adiabatic calorimetry over the range 7-350 K on [gamma] phase preparations of four lanthanide sesquisulfides, and the heat capacities were resolved into lattice, magnetic, Schottky and other components. The entropy at 298.15 K for La2S3 which is written as S[deg]/R is 19.51 while values of S[deg] -- S[deg](7 K) for Ce2S3, Nd2S3, Gd2S3 and Dy2S3 are 21.34, 22.38, 20.05 and 22.58 respectively. IR and visible optical spectra of La2S3, Ce2S3, Nd2S3 and Dy2S3 and lattice sum crystal field splitting calculations for Nd2S3, Ce2S3 and Dy2S3 are compared with Raman scattering data and Schottky contributions derived from calorimetry.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25086/1/0000517.pd
E-retailing ethics in Egypt and its effect on customer repurchase intention
The theoretical understanding of online shopping behaviour has received much attention. Less focus has been given to the formation of the ethical issues that result from online shopper interactions with e-retailers. The vast majority of earlier research on this area is conceptual in nature and limited in scope by focusing on consumersâ privacy issues. Therefore, the purpose of this paper is to propose a theoretical model explaining what factors contribute to online retailing ethics and its effect on customer repurchase intention. The data were analysed using variance-based structural equation modelling, employing partial least squares regression. Findings indicate that the five factors of the online retailing ethics (security, privacy, non- deception, fulfilment/reliability, and corporate social responsibility) are strongly predictive of online consumersâ repurchase intention. The results offer important implications for e-retailers and are likely to stimulate further research in the area of e-ethics from the consumersâ perspective
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
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