211 research outputs found
Evolution of the magnetic properties and magnetic structures along the RmMIn3m+2 (R = Ce, Nd, Gd, Tb; M = Rh, Ir; and m=1,2) series of intermetallic compounds
We discuss the evolution of the magnetic properties and magnetic structures along the series of intermetallic compounds RmMIn3m+2 (R=Ce, Nd, Gd, Tb; M=Rh, Ir; and m=1,2). The m=1,2 are, respectively, the single layer and bilayer tetragonal derivatives of their cubic RIn3 relatives. Using a mean field model including an isotropic first-neighbors Ruderman-Kittel-Kasuya-Yoshida interaction (K) and the tetragonal crystalline electrical field (CEF), we demonstrated that, for realistic values of K and CEF parameters, one can qualitatively describe the direction of the ordered moments and the behavior of the ordering temperature for these series. The particular case, where the rare-earth ordered moments lie in the ab plane or are tilted from the c axis and T-N can be reduced by tuning the CEF parameters, revealed an interesting kind of frustration that may be relevant to the physical properties of complex classes of materials such as the RmMIn3m+2 (M=Rh, Ir, and Co; m=1,2) heavy-fermion superconductors. (C) 2006 American Institute of Physics.99
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Factors associated with unintended pregnancy in Brazil: cross-sectional results from the Birth in Brazil National Survey, 2011/2012
Background
Unintended pregnancy, a pregnancy that have been either unwanted or mistimed, is a serious public health issue in Brazil. It is reported for more than half of women who gave birth in the country, but the characteristics of women who conceive unintentionally are rarely documented. The aim of this study is to analyse the prevalence and the association between unintended pregnancy and a set of sociodemographic characteristics, individual-level variables and history of obstetric outcomes.
Methods
Birth in Brazil is a cross-sectional study with countrywide representation that interviewed 23,894 women after birth. The information about intendedness of pregnancy was obtained after birth at the hospital and classified into three categories: intended, mistimed or unwanted. Multinomial regression analysis was used to estimate the associations between intendedness of a pregnancy, and sociodemographic and obstetric variables, calculating odds ratios and 95 % confidence intervals. All significant variables in the bivariate analysis were included in the multinomial multivariate model and the final model retaining variables that remained significant at the 5 % level.
Results
Unintended pregnancy was reported by 55.4 % of postpartum women. The following variables maintained positive and significant statistical associations with mistimed pregnancy: maternal ageâ<â20 years (ORâ=â1.89, 95 % CI: 1.68â2.14); brown (ORâ=â1.15, 95 % CI: 1.04â1.27) or yellow skin color (ORâ=â1.56, 95 % CI: 1.05â2.32); having no partner (ORâ=â2.32, 95 % CI: 1.99â2.71); having no paid job (ORâ=â1.15, 95 % CI: 1.04â1.27); alcohol abuse with risk of alcoholism (ORâ=â1.25, 95 % CI: 1.04â1.50) and having had three or more births (ORâ=â2.01, 95 % CI: 1.63â2.47). The same factors were associated with unwanted pregnancy, though the strength of the associations was generally stronger. Women with three or more births were 14 times more likely to have an unwanted pregnancy, and complication in the previous pregnancies and preterm birth were 40 % and 19 % higher, respectively. Previous neonatal death was a protective factor for both mistimed (ORâ=â0.61, 95 % CI: 0.44â0.85) and unwanted pregnancy (ORâ=â0.44, 95 % CI: 0.34â0.57).
Conclusions
This study confirms findings from previous research about the influence of socioeconomic and individual risk factors on unintended pregnancy. It takes a new approach to the problem by showing the importance of previous neonatal death, preterm birth and complication during pregnancy as risk factors for unintended pregnancy
Study of decays to the final state and evidence for the decay
A study of decays is performed for the first time
using data corresponding to an integrated luminosity of 3.0
collected by the LHCb experiment in collisions at centre-of-mass energies
of and TeV. Evidence for the decay
is reported with a significance of 4.0 standard deviations, resulting in the
measurement of
to
be .
Here denotes a branching fraction while and
are the production cross-sections for and mesons.
An indication of weak annihilation is found for the region
, with a significance of
2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html,
link to supplemental material inserted in the reference
A terrestrial planet candidate in a temperate orbit around Proxima Centauri
At a distance of 1.295 parsecs, the red dwarf Proxima Centauri (α Centauri C, GL 551, HIP 70890 or simply Proxima) is the Sunâs closest stellar neighbour and one of the best-studied low-mass stars. It has an effective temperature of only around 3,050 kelvin, a luminosity of 0.15 per cent of that of the Sun, a measured radius of 14 per cent of the radius of the Sun and a mass of about 12 per cent of the mass of the Sun. Although Proxima is considered a moderately active star, its rotation period is about 83 days and its quiescent activity levels and X-ray luminosity are comparable to those of the Sun. Here we report observations that reveal the presence of a small planet with a minimum mass of about 1.3 Earth masses orbiting Proxima with a period of approximately 11.2 days at a semi-major-axis distance of around 0.05 astronomical units. Its equilibrium temperature is within the range where water could be liquid on its surface
Health impact of US military service in a large population-based military cohort: findings of the Millennium Cohort Study, 2001-2008
<p>Abstract</p> <p>Background</p> <p>Combat-intense, lengthy, and multiple deployments in Iraq and Afghanistan have characterized the new millennium. The US military's all-volunteer force has never been better trained and technologically equipped to engage enemy combatants in multiple theaters of operations. Nonetheless, concerns over potential lasting effects of deployment on long-term health continue to mount and are yet to be elucidated. This report outlines how findings from the first 7 years of the Millennium Cohort Study have helped to address health concerns related to military service including deployments.</p> <p>Methods</p> <p>The Millennium Cohort Study was designed in the late 1990s to address veteran and public concerns for the first time using prospectively collected health and behavioral data.</p> <p>Results</p> <p>Over 150 000 active-duty, reserve, and National Guard personnel from all service branches have enrolled, and more than 70% of the first 2 enrollment panels submitted at least 1 follow-up survey. Approximately half of the Cohort has deployed in support of operations in Iraq and Afghanistan.</p> <p>Conclusion</p> <p>The Millennium Cohort Study is providing prospective data that will guide public health policymakers for years to come by exploring associations between military exposures and important health outcomes. Strategic studies aim to identify, reduce, and prevent adverse health outcomes that may be associated with military service, including those related to deployment.</p
Chagasic Thymic Atrophy Does Not Affect Negative Selection but Results in the Export of Activated CD4+CD8+ T Cells in Severe Forms of Human Disease
Extrathymic CD4+CD8+ double-positive (DP) T cells are increased in some pathophysiological conditions, including infectious diseases. In the murine model of Chagas disease, it has been shown that the protozoan parasite Trypanosoma cruzi is able to target the thymus and induce alterations of the thymic microenvironment and the lymphoid compartment. In the acute phase, this results in a severe atrophy of the organ and early release of DP cells into the periphery. To date, the effect of the changes promoted by the parasite infection on thymic central tolerance has remained elusive. Herein we show that the intrathymic key elements that are necessary to promote the negative selection of thymocytes undergoing maturation during the thymopoiesis remains functional during the acute chagasic thymic atrophy. Intrathymic expression of the autoimmune regulator factor (Aire) and tissue-restricted antigen (TRA) genes is normal. In addition, the expression of the proapoptotic Bim protein in thymocytes was not changed, revealing that the parasite infection-induced thymus atrophy has no effect on these marker genes necessary to promote clonal deletion of T cells. In a chicken egg ovalbumin (OVA)-specific T-cell receptor (TCR) transgenic system, the administration of OVA peptide into infected mice with thymic atrophy promoted OVA-specific thymocyte apoptosis, further indicating normal negative selection process during the infection. Yet, although the intrathymic checkpoints necessary for thymic negative selection are present in the acute phase of Chagas disease, we found that the DP cells released into the periphery acquire an activated phenotype similar to what is described for activated effector or memory single-positive T cells. Most interestingly, we also demonstrate that increased percentages of peripheral blood subset of DP cells exhibiting an activated HLA-DR+ phenotype are associated with severe cardiac forms of human chronic Chagas disease. These cells may contribute to the immunopathological events seen in the Chagas disease
Mechanisms and therapeutic applications of electromagnetic therapy in Parkinson's disease
© 2015 Vadalà et al. Electromagnetic therapy is a non-invasive and safe approach for the management of several pathological conditions including neurodegenerative diseases. Parkinson's disease is a neurodegenerative pathology caused by abnormal degeneration of dopaminergic neurons in the ventral tegmental area and substantia nigra pars compacta in the midbrain resulting in damage to the basal ganglia. Electromagnetic therapy has been extensively used in the clinical setting in the form of transcranial magnetic stimulation, repetitive transcranial magnetic stimulation, high-frequency transcranial magnetic stimulation and pulsed electromagnetic field therapy which can also be used in the domestic setting. In this review, we discuss the mechanisms and therapeutic applications of electromagnetic therapy to alleviate motor and non-motor deficits that characterize Parkinson's disease
Observation of B(s)0âJ/ÏppÂŻ decays and precision measurements of the B(s)0 masses
The first observation of the decays
B
0
(
s
)
â
J
/
Ï
p
ÂŻ
p
is reported, using proton-proton collision data corresponding to an integrated luminosity of
5.2
â
â
fb
â
1
, collected with the LHCb detector. These decays are suppressed due to limited available phase space, as well as due to Okubo-Zweig-Iizuka or Cabibbo suppression. The measured branching fractions are
B
(
B
0
â
J
/
Ï
p
ÂŻ
p
)
=
[
4.51
±
0.40
(
stat
)
±
0.44
(
syst
)
]
Ă
10
â
7
,
B
(
B
0
s
â
J
/
Ï
p
ÂŻ
p
)
=
[
3.58
±
0.19
(
stat
)
±
0.39
(
syst
)
]
Ă
10
â
6
. For the
B
0
s
meson, the result is much higher than the expected value of
O
(
10
â
9
)
. The small available phase space in these decays also allows for the most precise single measurement of both the
B
0
mass as
5279.74
±
0.30
(
stat
)
±
0.10
(
syst
)
â
â
MeV
and the
B
0
s
mass as
5366.85
±
0.19
(
stat
)
±
0.13
(
syst
)
â
â
MeV
Measurement of the B0s âJ/Ïη lifetime
Using a data set corresponding to an integrated luminosity of 3 fbâ1, collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV, the effective lifetime in the Bs0âJ/Ïη decay mode, Ïeff, is measured to be
Ïeff=1.479±0.034 (stat)±0.011 (syst) ps. Assuming CP conservation, Ïeff corresponds to the lifetime of the light Bs0 mass eigenstate. This is the first measurement of the effective lifetime in this decay mode
Measurement of the differential branching fraction
The branching fraction of the rare decay is measured for the first time, in the squared dimuon mass
intervals, , excluding the and regions. The data
sample analyzed was collected by the LHCb experiment at center-of-mass energies
of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of $9\
\mathrm{fb}^{-1}q^{2}q^{2} >15.0\
\mathrm{GeV}^2/c^4$, where theoretical predictions have the smallest model
dependence, agrees with the predictions.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-050.html (LHCb
public pages
- âŠ