3,327 research outputs found
Dietary patterns and non-communicable disease risk in Indian adults : secondary analysis of Indian Migration Study data
Acknowledgements The authors thank the IMS study team members and field staff involved in the generation and processing of IMS data. Financial support: This study forms part of the Sustainable and Healthy Diets in India (SAHDI) project supported by the Wellcome Trust ‘Our Planet, Our Health’ programme (grant number 103932). The Wellcome Trust had no role in the design, analysis or writing of this article. The IMS was funded by Wellcome Trust (grant number GR070797MF). L.A.’s PhD studentship is funded by the Leverhulme Centre for Integrative Research on Agriculture and Health (LCIRAH).Peer reviewedPublisher PD
Exact ground states for the four-electron problem in a Hubbard ladder
The exact ground state of four electrons in an arbitrary large two leg
Hubbard ladder is deduced from nine analytic and explicit linear equations. The
used procedure is described, and the properties of the ground state are
analyzed. The method is based on the construction in r-space of the different
type of orthogonal basis wave vectors which span the subspace of the Hilbert
space containing the ground state. In order to do this, we start from the
possible microconfigurations of the four particles within the system. These
microconfigurations are then rotated, translated and spin-reversed in order to
build up the basis vectors of the problem. A closed system of nine analytic
linear equations is obtained whose secular equation, by its minimum energy
solution, provides the ground state energy and the ground state wave function
of the model.Comment: 10 pages, 7 figure
Transformation of spin information into large electrical signals via carbon nanotubes
Spin electronics (spintronics) exploits the magnetic nature of the electron,
and is commercially exploited in the spin valves of disc-drive read heads.
There is currently widespread interest in using industrially relevant
semiconductors in new types of spintronic devices based on the manipulation of
spins injected into a semiconducting channel between a spin-polarized source
and drain. However, the transformation of spin information into large
electrical signals is limited by spin relaxation such that the magnetoresistive
signals are below 1%. We overcome this long standing problem in spintronics by
demonstrating large magnetoresistance effects of 61% at 5 K in devices where
the non-magnetic channel is a multiwall carbon nanotube that spans a 1.5 micron
gap between epitaxial electrodes of the highly spin polarized manganite
La0.7Sr0.3MnO3. This improvement arises because the spin lifetime in nanotubes
is long due the small spin-orbit coupling of carbon, because the high nanotube
Fermi velocity permits the carrier dwell time to not significantly exceed this
spin lifetime, because the manganite remains highly spin polarized up to the
manganite-nanotube interface, and because the interfacial barrier is of an
appropriate height. We support these latter statements regarding the interface
using density functional theory calculations. The success of our experiments
with such chemically and geometrically different materials should inspire
adventure in materials selection for some future spintronicsComment: Content highly modified. New title, text, conclusions, figures and
references. New author include
Explaining the t tbar forward-backward asymmetry without dijet or flavor anomalies
We consider new physics explanations of the anomaly in the top quark
forward-backward asymmetry measured at the Tevatron, in the context of flavor
conserving models. The recently measured LHC dijet distributions strongly
constrain many otherwise viable models. A new scalar particle in the
antitriplet representation of flavor and color can fit the t tbar asymmetry and
cross section data at the Tevatron and avoid both low- and high-energy bounds
from flavor physics and the LHC. An s-channel resonance in uc to uc scattering
at the LHC is predicted to be not far from the current sensitivity. This model
also predicts rich top quark physics for the early LHC from decays of the new
scalar particles. Single production gives t tbar j signatures with high
transverse momentum jet, pair production leads to t tbar j j and 4 jet final
states.Comment: 7 pages, 6 figures; v2: notation clarified, references adde
Interleukin-6 gene (IL-6): a possible role in brain morphology in the healthy adult brain
Background: Cytokines such as interleukin 6 (IL-6) have been implicated in dual functions in neuropsychiatric disorders. Little is known about the genetic predisposition to neurodegenerative and neuroproliferative properties of cytokine genes. In this study the potential dual role of several IL-6 polymorphisms in brain morphology is investigated. Methodology: In a large sample of healthy individuals (N = 303), associations between genetic variants of IL-6 (rs1800795; rs1800796, rs2069833, rs2069840) and brain volume (gray matter volume) were analyzed using voxel-based morphometry (VBM). Selection of single nucleotide polymorphisms (SNPs) followed a tagging SNP approach (e.g., Stampa algorigthm), yielding a capture 97.08% of the variation in the IL-6 gene using four tagging SNPs. Principal findings/results: In a whole-brain analysis, the polymorphism rs1800795 (−174 C/G) showed a strong main effect of genotype (43 CC vs. 150 CG vs. 100 GG; x = 24, y = −10, z = −15; F(2,286) = 8.54, puncorrected = 0.0002; pAlphaSim-corrected = 0.002; cluster size k = 577) within the right hippocampus head. Homozygous carriers of the G-allele had significantly larger hippocampus gray matter volumes compared to heterozygous subjects. None of the other investigated SNPs showed a significant association with grey matter volume in whole-brain analyses. Conclusions/significance: These findings suggest a possible neuroprotective role of the G-allele of the SNP rs1800795 on hippocampal volumes. Studies on the role of this SNP in psychiatric populations and especially in those with an affected hippocampus (e.g., by maltreatment, stress) are warranted.Bernhard T Baune, Carsten Konrad, Dominik Grotegerd, Thomas Suslow, Eva Birosova, Patricia Ohrmann, Jochen Bauer, Volker Arolt, Walter Heindel, Katharina Domschke, Sonja Schöning, Astrid V Rauch, Christina Uhlmann, Harald Kugel and Udo Dannlowsk
Charge asymmetries of top quarks at hadron colliders revisited
A sizeable difference in the differential production cross section of top-
compared to antitop-quark production, denoted charge asymmetry, has been
observed at the Tevatron. The experimental results seem to exceed the theory
predictions based on the Standard Model by a significant amount and have
triggered a large number of suggestions for "new physics". In the present paper
the Standard Model predictions for Tevatron and LHC experiments are revisited.
This includes a reanalysis of electromagnetic as well as weak corrections,
leading to a shift of the asymmetry by roughly a factor 1.1 when compared to
the results of the first papers on this subject. The impact of cuts on the
transverse momentum of the top-antitop system is studied. Restricting the ttbar
system to a transverse momentum less than 20 GeV leads to an enhancement of the
asymmetries by factors between 1.3 and 1.5, indicating the importance of an
improved understanding of the -momentum distribution. Predictions for
similar measurements at the LHC are presented, demonstrating the sensitivity of
the large rapidity region both to the Standard Model contribution and effects
from "new physics".Comment: 23 pages. Final version to appear in JHE
Proactive environmental strategy in a supply chain context: The mediating role of investments
Abstract: There is a growing body of knowledge on the link between environmental management and supply
chain management, but there is contradicting evidence on the impact of a proactive environmental strategy on environmental performance. Therefore, this paper investigates the impact of proactive environmental strategy on environmental performance as mediated by environmental investments.
We also consider the antecedents of the adoption of proactive environmental strategy. We develop and test hypotheses, using data collected from 96 Turkish manufacturers through an online questionnaire. The model was tested using Partial Least Squares (PLS), a structural equation modelling method. The results show that a proactive environmental strategy leads to higher environmental investments; both internally and externally in collaboration with suppliers. Our findings support our hypothesis that environmental investments acts as a mediating variable between proactive environmental strategy and environmental performance. The results also show that customer pressure and, particularly, organizational commitment positively impact the extent to which firms adopt a proactive environmental strategy
Isolated and dynamical horizons and their applications
Over the past three decades, black holes have played an important role in
quantum gravity, mathematical physics, numerical relativity and gravitational
wave phenomenology. However, conceptual settings and mathematical models used
to discuss them have varied considerably from one area to another. Over the
last five years a new, quasi-local framework was introduced to analyze diverse
facets of black holes in a unified manner. In this framework, evolving black
holes are modeled by dynamical horizons and black holes in equilibrium by
isolated horizons. We review basic properties of these horizons and summarize
applications to mathematical physics, numerical relativity and quantum gravity.
This paradigm has led to significant generalizations of several results in
black hole physics. Specifically, it has introduced a more physical setting for
black hole thermodynamics and for black hole entropy calculations in quantum
gravity; suggested a phenomenological model for hairy black holes; provided
novel techniques to extract physics from numerical simulations; and led to new
laws governing the dynamics of black holes in exact general relativity.Comment: 77 pages, 12 figures. Typos and references correcte
In vitro mycorrhization of micropropagated plants: studies on Castanea sativa Mill.
In vitro mycorrhization can be made by several axenic and nonaxenic
techniques but criticism exists about their artificiality and inability to
reproduce under natural conditions. However, artificial mycorrhization under
controlled conditions can provide important information about the physiology
of symbiosis. Micropropagated Castanea sativa plants were inoculated with
the mycorrhizal fungus Pisolithus tinctorius after in vitro rooting. The
mycorrhizal process was monitored at regular intervals in order to evaluate the
mantle and hartig net formation, and the growth rates of mycorrhizal and
nonmycorrhizal plants. Plant roots show fungal hyphae adhesion at the surface
after 24 hours of mycorrhizal induction. After 20 days a mantle can be
observed and a hartig net is forming although the morphology of the epidermal
cells remains unaltered. At 30 days of root–fungus contact the hartig net is
well developed and the epidermal cells are already enlarged. After 50 days of
mycorrhizal induction, growth was higher for mycorrhizal plants than for
nonmycorrhizal ones. The length of the major roots was lower in mycorrhizal
plants after 40 days. Fresh and dry weights were higher in mycorrhizal plants
after 30 days. The growth rates of chestnut mycorrhizal plants are in agreement
with the morphological development of the mycorrhizal structures observed at
each mycorrhizal time. The assessment of symbiotic establishment takes into
account the formation of a mantle and a hartig net that were already developed
at 30 days, when differences between fresh and dry weights of mycorrhizal and
nonmycorrhizal plants can be quantified. In vitro conditions, mycorrhization
influences plant physiology after 20 days of root–fungus contact, namely in
terms of growth rates. Fresh and dry weights, heights, stem diameter and
growth rates increased while major root growth rate decreased in mycorrhizal
plants.Springe
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