53 research outputs found
Reflection of electrons from a domain wall in magnetic nanojunctions
Electronic transport through thin and laterally constrained domain walls in
ferromagnetic nanojunctions is analyzed theoretically. The description is
formulated in the basis of scattering states. The resistance of the domain wall
is calculated in the regime of strong electron reflection from the wall. It is
shown that the corresponding magnetoresistance can be large, which is in a
qualitative agreement with recent experimental observations. We also calculate
the spin current flowing through the wall and the spin polarization of electron
gas due to reflections from the domain wall.Comment: 7 pages, 4 figure
Improving womenâs diet quality pre-conceptionally and during gestation: effects on birth weight and prevalence of low birth weight; a randomized controlled efficacy trial in India (Mumbai Maternal Nutrition Project)
BACKGROUND: Low birth weight (LBW) is an important public health problem in undernourished populations.OBJECTIVE: We tested whether improving women's dietary micronutrient quality before conception and throughout pregnancy increases birth weight in a high-risk Indian population.DESIGN: The study was a nonblinded, individually randomized controlled trial. The intervention was a daily snack made from green leafy vegetables, fruit, and milk (treatment group) or low-micronutrient vegetables (potato and onion) (control group) from ? 90 d before pregnancy until delivery in addition to the usual diet. Treatment snacks contained 0.69 MJ of energy (controls: 0.37 MJ) and 10-23% of WHO Reference Nutrient Intakes of ?-carotene, riboflavin, folate, vitamin B-12, calcium, and iron (controls: 0-7%). The primary outcome was birth weight.RESULTS: Of 6513 women randomly assigned, 2291 women became pregnant, 1962 women delivered live singleton newborns, and 1360 newborns were measured. In an intention-to-treat analysis, there was no overall increase in birth weight in the treatment group (+26 g; 95% CI: -15, 68 g; P = 0.22). There was an interaction (P < 0.001) between the allocation group and maternal prepregnant body mass index (BMI; in kg/m(2)) [birth-weight effect: -23, +34, and +96 g in lowest (<18.6), middle (18.6-21.8), and highest (>21.8) thirds of BMI, respectively]. In 1094 newborns whose mothers started supplementation ? 90 d before pregnancy (per-protocol analysis), birth weight was higher in the treatment group (+48 g; 95% CI: 1, 96 g; P = 0.046). Again, the effect increased with maternal BMI (-8, +79, and +113 g; P-interaction = 0.001). There were similar results for LBW (intention-to-treat OR: 0.83; 95% CI: 0.66, 1.05; P = 0.10; per-protocol OR = 0.76; 95% CI: 0.59, 0.98; P = 0.03) but no effect on gestational age in either analysis.CONCLUSIONS: A daily snack providing additional green leafy vegetables, fruit, and milk before conception and throughout pregnancy had no overall effect on birth weight. Per-protocol and subgroup analyses indicated a possible increase in birth weight if the mother was supplemented ? 3 mo before conception and was not underweight. This trial was registered at www.controlled-trials.com/isrctn/ as ISRCTN62811278<br/
Evidence of Color Coherence Effects in W+jets Events from ppbar Collisions at sqrt(s) = 1.8 TeV
We report the results of a study of color coherence effects in ppbar
collisions based on data collected by the D0 detector during the 1994-1995 run
of the Fermilab Tevatron Collider, at a center of mass energy sqrt(s) = 1.8
TeV. Initial-to-final state color interference effects are studied by examining
particle distribution patterns in events with a W boson and at least one jet.
The data are compared to Monte Carlo simulations with different color coherence
implementations and to an analytic modified-leading-logarithm perturbative
calculation based on the local parton-hadron duality hypothesis.Comment: 13 pages, 6 figures. Submitted to Physics Letters
Search for electroweak production of single top quarks in collisions.
We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ~90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DZero detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an upper limit at the 95% confidence level on the cross section for the s-channel process ppbar->tb+X of 39 pb. The upper limit for the t-channel process ppbar->tqb+X is 58 pb. (arXiv
Helicity of the W Boson in Lepton+Jets ttbar Events
We examine properties of ttbar candidates events in lepton+jets final states
to establish the helicities of the W bosons in t->W+b decays. Our analysis is
based on a direct calculation of a probability that each event corresponds to a
ttbar final state, as a function of the helicity of the W boson. We use the 125
events/pb sample of data collected by the DO experiment during Run I of the
Fermilab Tevatron collider at sqrt{s}=1.8 TeV, and obtain a longitudinal
helicity fraction of F_0=0.56+/-0.31, which is consistent with the prediction
of F_0=0.70 from the standard model
Hard Single Diffraction in pbarp Collisions at root-s = 630 and 1800 GeV
Using the D0 detector, we have studied events produced in proton-antiproton
collisions that contain large forward regions with very little energy
deposition (``rapidity gaps'') and concurrent jet production at center-of-mass
energies of root-s = 630 and 1800 Gev. The fractions of forward and central jet
events associated with such rapidity gaps are measured and compared to
predictions from Monte Carlo models. For hard diffractive candidate events, we
use the calorimeter to extract the fractional momentum loss of the scattered
protons.Comment: 11 pages 4 figures. submitted to PR
Precursor Shear Elastic Pseudo-Isotropy in Near Second Order Martensitic Phase Transitions
In contrast to the behavior of the isentropic elastic constants both isothermal constants, C' and C44, of In-Cd, In-Tl and Fe-Pd alloys soften on approaching the martensite start temperature. The isothermal, i.e. low frequency, â500Hz, anisotropy ratio approaches a value of unity as the martensitic transformation is approached from above. The parent phase becomes shear elastically pseudo-isotropic. Close to the transition, this shear pseudo-isotropy reflects the reorientation of incipient variants in the cubic phase under the influence of the dynamic measuring stress. It represents a true dynamical precursor of this fcc fct near second order martensitic phase transition
- âŠ