1,153 research outputs found
Nanoengineered Curie Temperature in Laterally-Patterned Ferromagnetic Semiconductor Heterostructures
We demonstrate the manipulation of the Curie temperature of buried layers of
the ferromagnetic semiconductor (Ga,Mn)As using nanolithography to enhance the
effect of annealing. Patterning the GaAs-capped ferromagnetic layers into
nanowires exposes free surfaces at the sidewalls of the patterned (Ga,Mn)As
layers and thus allows the removal of Mn interstitials using annealing. This
leads to an enhanced Curie temperature and reduced resistivity compared to
unpatterned samples. For a fixed annealing time, the enhancement of the Curie
temperature is larger for narrower nanowires.Comment: Submitted to Applied Physics Letters (minor corrections
An Observational Pursuit for Population III Stars in a Ly_alpha Emitter at z=6.33 through HeII Emission
We present a very deep near-infrared spectroscopic observation of a strong
Ly_alpha emitter at z=6.33, SDF J132440.6+273607, which we used to search for
HeII 1640. This emission line is expected if the target hosts a significant
number of population III stars. Even after 42 ksec of integration with the
Subaru/OHS spectrograph, no emission-line features are detected in the JH band,
which confirms that SDF J132440.6+273607 is neither an active galactic nucleus
nor a low- emission-line object. We obtained a 2sigma upper-limit of
9.06e-18 ergs/s/cm^2 on the HeII 1640 emission line flux, which corresponds to
a luminosity of 4.11e42 ergs/s. This upper-limit on the HeII 1640 luminosity
implies that the upper limit on population III star-formation rate is in the
range 4.9--41.2 M_sun/yr if population III stars suffer no mass loss, and in
the range 1.8--13.2 M_sun/yr if strong mass loss is present. The non-detection
of HeII in SDF J132440.6+273607 at z=6.33 may thus disfavor weak feedback
models for population III stars.Comment: 13 pages, 3 figures, to appear in The Astrophysical Journal Letter
Quality Evaluation of Feed Resources at the Newly Reclaimed Area in Egypt
The objective of this study was to examine the productivity of Egyptian clover (Trifolium alexandrinum L.) interseeded with ryegrass (Lolium multiflorum) and alfalfa (Medicaga sativa L.). These species were planted in newly reclaimed land in Ismailia, Egypt under two fertilization systems; organic (OF) or chemical (CF) during winter season of (1994-1995) using a split plot design. Feeding quality of forages was evaluated by conducting digestibility trials with rams and feeding trials with growing lambs where forage was offered ad. libitum with 1% of LBW concentrate. Productivity data indicated that organic fertilization yielded significantly more DM. Chemical analysis showed that DM content with (CF) was higher than with (OF) and it was found that alfalfa had higher CP content than that of E. Clover mixture. Digestibility of nutrients was higher with (CF) than with (OF) and it was found that CP was more digested in alfalfa than the Egyptian clover mixture. TDN values for both forages were determined by proximate analysis. Group of lambs fed chemically fertilized alfalfa attained significantly better weight gain which was attributed to high forage DM intake
Equation of state for -stable hot nuclear matter
We provide an equation of state for hot nuclear matter in -equilibrium
by applying a momentum-dependent effective interaction. We focus on the study
of the equation of state of high-density and high-temperature nuclear matter,
containing leptons (electrons and muons) under the chemical equilibrium
condition in which neutrinos have left the system. The conditions of charge
neutrality and equilibrium under -decay process lead first to the
evaluation of proton and lepton fractions and afterwards of internal energy,
free energy, pressure and in total to the equation of state of hot nuclear
matter. Thermal effects on the properties and equation of state of nuclear
matter are assesed and analyzed in the framework of the proposed effective
interaction model. Special attention is dedicated to the study of the
contribution of the components of -stable nuclear matter to the entropy
per particle, a quantity of great interest for the study of structure and
collapse of supernova.Comment: 28 pages, 18 figure
Exchange Biasing of the Ferromagnetic Semiconductor Ga1-xMnxAs
We demonstrate the exchange coupling of a ferromagnetic semiconductor
(Ga1-xMnxAs) with an overgrown antiferromagnet (MnO). Unlike most conventional
exchange biased systems, the blocking temperature of the antiferromagnet (T_B =
48 +- 2 K) and the Curie temperature of the ferromagnet (T_C = 55.1 +- 0.2 K)
are comparable. The resulting exchange bias manifests itself as a clear shift
in the magnetization hysteresis loop when the bilayer is cooled in the presence
of an applied magnetic field and an enhancement of the coercive field.Comment: pdf file only; submitted to Applied Physics Letter
A photometric survey for Lyalpha-HeII dual emitters: Searching for Population III stars in high-redshift galaxies
We present a new photometric search for high-z galaxies hosting Population
III (PopIII) stars based on deep intermediate-band imaging observations
obtained in the Subaru Deep Field (SDF), by using Suprime-Cam on the Subaru
Telescope. By combining our new data with the existing broad-band and
narrow-band data, we searched for galaxies which emit strongly both in Ly_alpha
and in HeII 1640 (``dual emitters'') that are promising candidates for
PopIII-hosting galaxies, at 3.93<z<4.01 and 4.57<z<4.65. Although we found 10
``dual emitters'', most of them turn out to be [OII]-[OIII] dual emitters or
H_beta-(H_alpha+[NII]) dual emitters at z<1, as inferred from their broad-band
colors and from the ratio of the equivalent widths. No convincing candidate of
Ly_alpha-HeII dual emitter of SFR_PopIII > 2 Msun/yr was found by our
photometric search in 4.03 x 10^5 Mpc^3 in the SDF. This result disfavors low
feedback models for PopIII star clusters, and implies an upper-limit of the
PopIII SFR density of SFRD_PopIII < 5 x 10^-6 Msun/yr/Mpc^3. This new selection
method to search for PopIII-hosting galaxies should be useful in future
narrow-band surveys to achieve the first observational detection of
PopIII-hosting galaxies at high redshifts.Comment: 24 pages, 10 figures, accepted for publication in Ap
Exchange Biasing of the Ferromagnetic Semiconductor (Ga,Mn)As by MnO
We provide an overview of progress on the exchange biasing of a ferromagnetic
semiconductor (Ga1-xMnxAs) by proximity to an antiferromagnetic oxide layer
(MnO). We present a detailed characterization study of the antiferromagnetic
layer using Rutherford backscattering spectrometry, x-ray photoelectron
spectroscopy, transmission electron microscopy, and x-ray reflection. In
addition, we describe the variation of the exchange and coercive fields with
temperature and cooling field for multiple samples.Comment: To appear in J. Appl. Phys. (invited paper in Proceedings of the 49th
Annual Conference on Magnetism & Magnetic Materials); pdf file onl
The Availability Of Full Match Sibling Donors And Feasibility Of Allogeneic Bone Marrow Transplantation In Brazil.
The feasibility of allogeneic bone marrow transplantation (alloBMT) in a developing country has not yet been demonstrated. Many adverse factors including social and economic limitations may reduce the overall results of this complex and expensive procedure. Our objective was to characterize the most important clinical, social and economic features of candidates for transplantation and their potential donors as well as the influence of these factors on overall survival in a retrospective and exploratory analysis at a university hospital. From July 1993 to July 2001, candidates for BMT were referred to the Bone Marrow Transplantation Unit by Hematology and Oncology Centers from several regions of Brazil. A total of 1138 patients were referred to us as candidates for alloBMT. Median age was 25 years (range: 2 months-60 years), 684 (60.1%) were males and 454 (39.9%) were females. The clinical indications were severe aplastic anemia and hematological malignancies. From the total of 1138 patients, 923 had HLA-typing; 497/923 (53.8%) candidates had full match donors; 352/1138 (30.8%) were eligible for alloBMT. Only 235 of 352 (66.7%) were transplanted. Schooling was 1st to 8th grade for 123/235 (52.3%); monthly family income ranged from US400 (36%). Overall survival for patients with chronic myeloid leukemia, severe aplastic anemia and acute myeloid leukemia was 58, 60 and 30%, respectively. Thus, overall survival rates for the most frequent hematological diseases were similar to those reported in the International Registry, except for acute myeloid leukemia. This descriptive and exploratory analysis suggests the feasibility of alloBMT in a developing country like Brazil.36315-2
Can the relationship between overweight/obesity and sleep quality be explained by affect and behaviour?
Purpose Sleep impairment is reported to be a consequence of overweight and obesity. However, the weight–sleep relationship can alternately be explained by demographics (e.g. age) and covariates (i.e. mood/affect and behaviour in overweight/ obese people; e.g. night-eating). Thus, we examined the weight–sleep quality relationship after controlling for the effects of affect and common behaviour (i.e. night-eating, insufficient exercise, alcohol and electronic device use).Methods Online questionnaires asked 161 overweight, obese or normal-weight participants about their sleep quality, night-eating, physical activity, alcohol use, electronic device use and anxiety and depression at T0 (baseline) and T1 (3 months later). Height and weight and waist and hip circumference were objectively measured at T0 and T1, and physical activity was assessed over 24 h (using actigraphy) at T0 and T1. Hierarchical multiple regression analyses evaluated whether the weight measures (i.e. body-mass-index [BMI], waist-to-hip ratio [WHR] and obesity category [overweight/obese vs. normal-weight]) predicted sleep quality and its components at T0 and T1, after controlling demographics (at step 1) and covariates (affective distress and behaviour) at step 2, and entering weight measures at step 3; maximum 8 variables in the analyses.Results High BMI predicted several aspects of sleep quality after taking into account co-existing behaviour, affect and demographics: sleep disturbances at T0 and lower sleep efficiency at T1. WHR and obesity category did not predict any aspects of sleep quality. Several co-existing behaviour were related to or predicted sleep quality score and aspects of sleep quality including night-eating, alcohol use and electronic device use and affective symptoms (i.e. anxiety, depression).Conclusion Results suggest that a person's weight may impact on their sleep quality above and beyond the effects of their co-existing behaviour and affect, although their co-existing behaviour and affect may also adversely impact on sleep quality.Level of evidence Level III, evidence obtained from well-designed cohort
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