797 research outputs found
Keyframe-based visual–inertial odometry using nonlinear optimization
Combining visual and inertial measurements has become popular in mobile robotics, since the two sensing modalities offer complementary characteristics that make them the ideal choice for accurate visual–inertial odometry or simultaneous localization and mapping (SLAM). While historically the problem has been addressed with filtering, advancements in visual estimation suggest that nonlinear optimization offers superior accuracy, while still tractable in complexity thanks to the sparsity of the underlying problem. Taking inspiration from these findings, we formulate a rigorously probabilistic cost function that combines reprojection errors of landmarks and inertial terms. The problem is kept tractable and thus ensuring real-time operation by limiting the optimization to a bounded window of keyframes through marginalization. Keyframes may be spaced in time by arbitrary intervals, while still related by linearized inertial terms. We present evaluation results on complementary datasets recorded with our custom-built stereo visual–inertial hardware that accurately synchronizes accelerometer and gyroscope measurements with imagery. A comparison of both a stereo and monocular version of our algorithm with and without online extrinsics estimation is shown with respect to ground truth. Furthermore, we compare the performance to an implementation of a state-of-the-art stochastic cloning sliding-window filter. This competitive reference implementation performs tightly coupled filtering-based visual–inertial odometry. While our approach declaredly demands more computation, we show its superior performance in terms of accuracy
Timing of antiretroviral therapy in Cambodian hospital after diagnosis of tuberculosis: impact of revised WHO guidelines
OBJECTIVE: To determine if implementation of 2010 World Health Organization (WHO) guidelines on antiretroviral therapy (ART) initiation reduced delay from tuberculosis diagnosis to initiation of ART in a Cambodian urban hospital. METHODS: A retrospective cohort study was conducted in a nongovernmental hospital in Phnom Penh that followed new WHO guidelines in patients with human immunodeficiency virus (HIV) and tuberculosis. All ART-naïve, HIV-positive patients initiated on antituberculosis treatment over the 18 months before and after guideline implementation were included. A competing risk regression model was used. FINDINGS: After implementation of the 2010 WHO guidelines, 190 HIV-positive patients with tuberculosis were identified: 53% males; median age, 38 years; median baseline CD4+ T-lymphocyte (CD4+ cell) count, 43 cells/µL. Before implementation, 262 patients were identified; 56% males; median age, 36 years; median baseline CD4+ cell count, 59 cells/µL. With baseline CD4+ cell counts ≤ 50 cells/µL, median delay to ART declined from 5.8 weeks (interquartile range, IQR: 3.7–9.0) before to 3.0 weeks (IQR: 2.1–4.4) after implementation (P < 0.001); with baseline CD4+ cell counts > 50 cells/µL, delay dropped from 7.0 (IQR: 5.3–11.3) to 3.6 (IQR: 2.9–5.3) weeks (P < 0.001). The probability of ART initiation within 4 and 8 weeks after tuberculosis diagnosis rose from 23% and 65%, respectively, before implementation, to 62% and 90% after implementation. A non-significant increase in 6-month retention and antiretroviral substitution was seen after implementation. CONCLUSION: Implementation of 2010 WHO recommendations in a routine clinical setting shortens delay to ART. Larger studies with longer follow-up are needed to assess impact on patient outcomes
Effect of Flow on Caloric Curve for Finite Nuclei
In a finite temperature Thomas-Fermi theory, we construct caloric curves for
finite nuclei enclosed in a freeze-out volume few times the normal nuclear
volume, with and without inclusion of flow. Without flow, the caloric curve
indicates a smooth liquid-gas phase transition whereas with flow, the
transition may be very sharp. We discuss these results in the context of two
recent experiments, one for heavy symmetric system (Au + Au at 600A MeV) and
the other for highly asymmetric system (Au + C at 1A GeV) where different
behaviours in the caloric curves are seen.Comment: 11 pages revtex; 4 figs; version to appear in Phys. Rev. Let
Bacterial sepsis in patients with visceral leishmaniasis in Northwest Ethiopia
Background and Objectives. Visceral leishmaniasis (VL) is one of the neglected diseases affecting the poorest segment of world populations. Sepsis is one of the predictors for death of patients with VL. This study aimed to assess the prevalence and factors associated with bacterial sepsis, causative agents, and their antimicrobial susceptibility patterns among patients with VL. Methods. A cross-sectional study was conducted among parasitologically confirmed VL patients suspected of sepsis admitted to the University of Gondar Hospital, Northwest Ethiopia, from February 2012 to May 2012. Blood cultures and other clinical samples were collected and cultured following the standard procedures. Results. Among 83 sepsis suspected VL patients 16 (19.3%) had culture confirmed bacterial sepsis. The most frequently isolated organism was Staphylococcus aureus (68.8%; 11/16), including two methicillin-resistant isolates (MRSA). Patients with focal bacterial infection were more likely to have bacterial sepsis (P<0.001). Conclusions. The prevalence of culture confirmed bacterial sepsis was high, predominantly due to S. aureus. Concurrent focal bacterial infection was associated with bacterial sepsis, suggesting that focal infections could serve as sources for bacterial sepsis among VL patients. Careful clinical evaluation for focal infections and prompt initiation of empiric antibiotic treatment appears warranted in VL patients
Effect of Conjugated Linoleic Acids on Nutritional Status and Lipid Metabolism in Rats Fed Linoleic-Acid-Deprived Diets
This study aims to investigate the effect of conjugated linoleic acid (CLA) on nutritional parameters and triacylglycerol (TAG) regulation in male Wistar rats fed linoleic acid (LA)-deprived (−LA) diets compared to LA-enriched (+LA) diets. In both +LA and −LA groups, CLA are incorporated into the tissues, showing higher levels in the adipose tissue. However, different metabolic and nutritional effects are observed depending on the LA status. CLA markedly reduces fat depots in the −LA group, associated with an increased lipoprotein lipase (LPL) and lipogenic enzyme activities as compensatory mechanisms. Moreover, CLA restores the hepatic TAG levels in −LA animals, associated with a normalized triacylglycerol-secretion rate (TAG-SR), an increased lipogenic enzyme activity and higher mRNA levels of fatty acid synthase. Serum TAG levels are not affected by CLA in the +LA group. However, in the −LA group, CLA decreases the TAG levels associated with a reduced TAG-SR and a higher adipose tissue LPL activity. Thus, the CLA effects on the nutritional parameters and TAG metabolism differs depending on the LA status. CLA causes certain beneficial biological and nutritional effects in LA-deprived but not in LA-enriched animals. Practical Applications: The approach by the authors involve growing animals in healthy physiological conditions fed with diets containing recommended levels of dietary fats, moderate amounts of commercial CLA mixture obtained from industrial synthesis (equimolecular amounts of 9c,11t- and 10t,12c-isomers), and unbalanced LA levels. These variables constitute a situation observed in the human population. The present study might contribute to understanding the role of CLA on nutritional parameters and TAG metabolism depending on the nutritional milieu. Conjugated linoleic acid effects on nutritional parameters and triacylglycerol metabolism in rats fed linoleic-acid-enriched and linoleic-acid-deprived diets are determined.Fil: Fariña, Ana Clara. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas. Cátedra de Bromatología y Nutrición; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Lavandera, Jimena Veronica. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas. Cátedra de Bromatología y Nutrición; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: González, Marcela Aída. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas. Cátedra de Bromatología y Nutrición; ArgentinaFil: Bernal, Claudio Adrian. Universidad Nacional del Litoral. Facultad de Bioquímica y Ciencias Biológicas. Departamento de Ciencias Biológicas. Cátedra de Bromatología y Nutrición; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentin
Breakup Conditions of Projectile Spectators from Dynamical Observables
Momenta and masses of heavy projectile fragments (Z >= 8), produced in
collisions of 197Au with C, Al, Cu and Pb targets at E/A = 600 MeV, were
determined with the ALADIN magnetic spectrometer at SIS. An analysis of
kinematic correlations between the two and three heaviest projectile fragments
in their rest frame was performed. The sensitivity of these correlations to the
conditions at breakup was verified within the schematic SOS-model. The data
were compared to calculations with statistical multifragmentation models and to
classical three-body calculations. Classical trajectory calculations reproduce
the dynamical observables. The deduced breakup parameters, however, differ
considerably from those assumed in the statistical multifragmentation models
which describe the charge correlations. If, on the other hand, the analysis of
kinematic and charge correlations is performed for events with two and three
heavy fragments produced by statistical multifragmentation codes, a good
agreement with the data is found with the exception that the fluctuation widths
of the intrinsic fragment energies are significantly underestimated. A new
version of the multifragmentation code MCFRAG was therefore used to investigate
the potential role of angular momentum at the breakup stage. If a mean angular
momentum of 0.75/nucleon is added to the system, the energy fluctuations
can be reproduced, but at the same time the charge partitions are modified and
deviate from the data.
PACS numbers: 25.70.Mn, 25.70.Pq, 25.75.Ld, 25.75.-qComment: 38 pages, RevTeX with 21 included figures; Also available from
http://www-kp3.gsi.de/www/kp3/aladin_publications.htm
Pion radii in nonlocal chiral quark model
The electromagnetic radius of the charged pion and the transition radius of
the neutral pion are calculated in the framework of the nonlocal chiral quark
model. It is shown in this model that the contributions of vector mesons to the
pion radii are noticeably suppressed in comparison with a similar contribution
in the local Nambu--Jona-Lasinio model. The form-factor for the process
gamma*pi+pi- is calculated for the -1 GeV^2<q^2<1.6 GeV^2. Our results are in
satisfactory agreement with experimental data.Comment: 7 pages, 7 figure
Multiplicity correlations of intermediate-mass fragments with pions and fast protons in 12C + 197Au
Low-energy pi+ (E < 35 MeV) from 12C+197Au collisions at incident energies
from 300 to 1800 MeV per nucleon were detected with the Si-Si(Li)-CsI(Tl)
calibration telescopes of the INDRA multidetector. The inclusive angular
distributions are approximately isotropic, consistent with multiple
rescattering in the target spectator. The multiplicity correlations of the
low-energy pions and of energetic protons (E > 150 MeV) with intermediate-mass
fragments were determined from the measured coincidence data. The deduced
correlation functions 1 + R \approx 1.3 for inclusive event samples reflect the
strong correlations evident from the common impact-parameter dependence of the
considered multiplicities. For narrow impact-parameter bins (based on
charged-particle multiplicity), the correlation functions are close to unity
and do not indicate strong additional correlations. Only for pions at high
particle multiplicities (central collisions) a weak anticorrelation is
observed, probably due to a limited competition between these emissions.
Overall, the results are consistent with the equilibrium assumption made in
statistical multifragmentation scenarios. Predictions obtained with
intranuclear cascade models coupled to the Statistical Multifragmentation Model
are in good agreement with the experimental data.Comment: 9 pages, 11 figures, subm. to EPJ
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