14,956 research outputs found
On Dirac-like Monopoles in a Lorentz- and CPT-violating Electrodynamics
We study magnetic monopoles in a Lorentz- and CPT-odd electrodynamical
framework in (3+1) dimensions. This is the standard Maxwell model extended by
means of a Chern-Simons-like term, (
constant), which respects gauge invariance but violates both Lorentz and CPT
symmetries (as a consequence, duality is also lost). Our main interest concerns
the analysis of the model in the presence of Dirac monopoles, so that the
Bianchi identity no longer holds, which naively yields the non-conservation of
electric charge. Since gauge symmetry is respected, the issue of charge
conservation is more involved. Actually, the inconsistency may be circumvented,
if we assume that the appearance of a monopole induces an extra electric
current. The reduction of the model to (2+1) dimensions in the presence of both
the magnetic sources and Lorentz-violating terms is presented. There, a
quantization condition involving the scalar remnant of , say, the mass
parameter, is obtained. We also point out that the breaking of duality may be
associated with an asymmetry between electric and magnetic sources in this
background, so that the electromagnetic force experienced by a magnetic pole is
supplemented by an extra term proportional to , whenever compared to the
one acting on an electric charge.Comment: 10 pages, no figures, typed in te
HIV in pregnancy: a 9 year study of the seroprevalence, sociodemographic factors and pregnancy outcomes of seropositive women at a tertiary care hospital in Mumbai, Maharashtra, India
Background: HIV can cause considerable morbidity and mortality in those affected. An effective PPTCT programme helps in reducing the spread of HIV by vertical transmission and improving the life of the women and her baby.Methods: A retrospective study was done at a tertiary care hospital, including pregnant women registered and delivered at the hospital during a period of 9 years from January 2010 to December 2018. Pretest counseling, HIV testing, Post-test counseling were done and antiretroviral prophylaxis given as per the NACP guidelines. Sociodemographic characteristics, obstetric and maternal-foetal outcome of seropositive women and efficacy of PPTCT services were analyzed.Results: Out of the 58,205 antenatal mothers included, 55,256 (94.93%) accepted HIV testing. 171 of these tested positive (0.31%). 70 spouses of the 171 seropositive women tested positive, 53 tested negative and 48 did not undergo the HIV test. Majority of seropositive women were primigravidas; housewives from urban areas, from low income and educational background and with no history of any contraceptive use. 7.6% had an MTP, 1.75% a spontaneous abortion and 0.58% an ectopic pregnancy. Of the 154 births, 35.71% underwent caesarean sections. There were 96.7% live births in our study and the perinatal mortality rate was 5.19%. After 2013, all mother-baby pairs were given ARV prophylaxis.Conclusions: Utilization of PPTCT services has increased through the years, decreasing the vertical transmission and seroprevalence rate. Increasing the acceptance rates of HIV testing, both by patients and partners may further help in curbing the spread of this condition
A rare case of abdominal pregnancy: diagnostic and therapeutic challenges
Abdominal pregnancy refers to a pregnancy that has implanted in the abdominal cavity, the estimated incidence being 1 per 30,000 births. A 36-year-old primigravida with term pregnancy with fetal demise was referred to us. Examination was suggestive of single foetus of 30 weeks’ gestation with longitudinal lie and cephalic presentation with absent foetal heart sounds. The cervical os was closed, uneffaced. Ultrasound done at 18 weeks’ gestation had reported pregnancy in a bicornuate uterus. Present ultrasound revealed intrauterine foetal demise of 28.4 weeks. Cervical ripening, done using prostaglandins, mechanical dilation with Foley’s catheter and oxytocin, had failed, and thus patient was taken up for surgery. Findings revealed an abdominal pregnancy with a macerated fetus of 1070 grams (severely growth restricted). Placenta was found to be implanted on multiple areas of both small and large intestine and posterior peritoneum. Placenta was left in situ. Postoperative recovery was uneventful. She was given higher antibiotics, 4 doses of tablet mifepristone 200 mg and monitored regularly with ultrasound/ MRI and bHCG which showed slow placental resorption. Conclusion- Abdominal pregnancies, associated with a high maternal and perinatal morbidity and mortality, are diagnosed preoperatively only in 45% of cases. Thus, a high index of suspicion and improvement in diagnosis is the need of the hour. Successful management includes prompt intraoperative recognition and management of the placenta (we advocate leaving the placenta in situ), multidisciplinary approach with involvement of surgeons and interventional radiologists, access to blood products, meticulous postoperative care and close observation during the subsequent delayed reabsorption
The pinewood nematode, Bursaphelenchus xylophilus, in Madeira Island
The environmental conditions in Madeira Island are favorable
for the presence and dissemination of the pinewood
nematode (PWN), Bursaphelenchus xylophilus. Five hundred
Pinus pinaster wood samples were collected in several
forest areas and PWN was detected in 22.8 % of the
samples. Bursaphelenchus xylophilus isolates from Madeira
Island displayed the species-specific diagnostic characters.
A morphological variation in the female tail terminus was
detected. In most females, the tail presented a broadly
rounded terminus and, occasionally, a digitate terminus with
a terminal nipple-like extension resembling a mucro. PCR
ITS-RFLP analysis revealed that Madeira Island isolates
exhibited patterns specific to the species B. xylophilus and
similar to virulent isolates. Amplified ITS regions were
further sequenced and no genetic diversity was found for
this genomic region among 17 Portuguese isolates (Madeira
Island and Continental Portugal). Phylogenetic analysis
revealed that Portuguese isolates grouped with isolates from
China, Korea and one isolate from Japa
Screening covalent immobilization of a recombinant cutinase for Esterification and Hydrolysis reactions in solvent-free reaction media
Trabalho apresentado em ISySYCat, setembro 2019, Évora, PortugalN/
Rank-(n – 1) convexity and quasiconvexity for divergence free fields
No description supplie
Metabolic factors in obesity
Obesity has a rising prevalence in children and adolescents, affecting 30% of the paediatric population in Portugal. Leptin is an important hormone involved in the pathogenesis of obesity and has been under investigation as a risk marker for future complications.
AIMS:
1. To evaluate the relation between serum leptin levels and body mass index (BMI) and height. 2. To compare leptin levels in obese and non-obese children. 3. To evaluate the relation between leptin levels and insulin resistance index.
METHODS:
Cross-sectional study, using a sample of 70 obese children and a control group of 53 non-obese children. Obesity was defined as BMI standard deviation > 2 for age and sex. In the obese group we assessed sex, age, BMI SDS and height SDS for age and sex, and serum levels of glucose, insulin and leptin. In the control group were obtained BMI SDS and height SDS for age and sex and leptin levels. Data were analysed using SPSS 12.
RESULTS:
The mean age of obese and non-obese children was 10.3 +/- 2.9 versus 10.9 +/- 3.5 years. In the obese group, 32 (45.7%) were boys versus 18 (31.0%) in the non-obese group. BMI SDS in the obese group was 3.12 +/- 0.60 versus 0.20 +/- 0.99 in the non-obese group (p < 0.001). Leptin levels showed a positive correlation with BMI SDS (r = 0.69; p < 0.001) and height SDS (r = 0.31; p < 0.001). When comparing leptin levels between obese and non-obese groups, we found a significant difference in boys (50.7 +/- 27.3 versus 7.0 +/- 6.8 ng/ml; p < 0.001) and in girls (57.6 +/- 25.5 versus 16.5 +/- 10.3 ng/ml; p < 0.001). In the nonobese group, leptin levels were lower in boys. This difference was not seen in the obese group. Leptin showed a positive correlation with insulin resistance index in boys (r = 0.45, p = 0.05), but not in girls.
CONCLUSIONS:
This study has confirmed a positive correlation between leptin levels and BMI SDS. In obese children elevated leptin is associated with central resistance to its action. The positive correlation of leptin with insulin resistance index may suggest a major role of leptin in insulin resistance.info:eu-repo/semantics/publishedVersio
Teaching robot modelling and control with RobLib
The paper presents a program for robotics education that runs on standard PC's under the Microsoft Windows environment. The RobLib package is designed for undergraduate students and emphasis the fundamental aspects of robot modelling and control. The software is self-explanatory and uses menus, dialog boxes with figures and context-dependent on-line help. In this perpective, students are motivated to investigate on the workspace, kinematics, dynamics, trajectory planning, position and force control of manipulators. Based on this first experience, further studies on robotics, using more sophisticated packages and concepts, are, then, more attractive from the students point of view.N/
Fractional-order position/force control of two cooperating manipulators
In this paper it is studied the implementation of fractional-order algorithms in the position/force control of two cooperating robotic manipulators. The system performance is analyzed in terms of time and frequency response for different operating condicitons.N/
Young Measures Generated by Ideal Incompressible Fluid Flows
In their seminal paper "Oscillations and concentrations in weak solutions of
the incompressible fluid equations", R. DiPerna and A. Majda introduced the
notion of measure-valued solution for the incompressible Euler equations in
order to capture complex phenomena present in limits of approximate solutions,
such as persistence of oscillation and development of concentrations.
Furthermore, they gave several explicit examples exhibiting such phenomena. In
this paper we show that any measure-valued solution can be generated by a
sequence of exact weak solutions. In particular this gives rise to a very
large, arguably too large, set of weak solutions of the incompressible Euler
equations.Comment: 35 pages. Final revised version. To appear in Arch. Ration. Mech.
Ana
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