250 research outputs found
Assessing the spatio-temporal spread of COVID-19 via compartmental models with diffusion in Italy, USA, and Brazil
The outbreak of COVID-19 in 2020 has led to a surge in interest in the
mathematical modeling of infectious diseases. Such models are usually defined
as compartmental models, in which the population under study is divided into
compartments based on qualitative characteristics, with different assumptions
about the nature and rate of transfer across compartments. Though most commonly
formulated as ordinary differential equation (ODE) models, in which the
compartments depend only on time, recent works have also focused on partial
differential equation (PDE) models, incorporating the variation of an epidemic
in space. Such research on PDE models within a Susceptible, Infected, Exposed,
Recovered, and Deceased (SEIRD) framework has led to promising results in
reproducing COVID-19 contagion dynamics. In this paper, we assess the
robustness of this modeling framework by considering different geometries over
more extended periods than in other similar studies. We first validate our code
by reproducing previously shown results for Lombardy, Italy. We then focus on
the U.S. state of Georgia and on the Brazilian state of Rio de Janeiro, one of
the most impacted areas in the world. Our results show good agreement with
real-world epidemiological data in both time and space for all regions across
major areas and across three different continents, suggesting that the modeling
approach is both valid and robust.Comment: 23 pages, 19 figure
A Cluster-Randomised Trial to Compare Home-Based with Health Facility-Based Antiretroviral Treatment in Uganda: Study Design and Baseline Findings
The scale-up of antiretroviral therapy is progressing rapidly in Africa but with a limited evidence-base. We report the baseline results from a large pragmatic cluster-randomised trial comparing different strategies of ART delivery. The trial is integrated in normal health service delivery.
1453 subjects were recruited into the study. Significantly more women (71%) than men (29%) were recruited. The WHO HIV clinical stage at presentation did not differ significantly between men and women: 58% and 53% respectively were at WHO stage III or IV (p=0.9). Median CD4 counts (IQR) x 106cells/l were 98 (28, 160) among men and 111 (36, 166) among women. Sixty-four percent of women and 61% men had plasma viral load ≥100,000 copies. Baseline characteristics did not change over time.
Considerably fewer men than women presented for treatment. Both men and women presented at an advanced stage with very low median CD4 count and high plasma viral load
3-3-1 Models at Electroweak Scale
We show that in 3-3-1 models there exist a natural relation among the
coupling constant , the electroweak mixing angle , the
mass of the , and one of the vacuum expectation values, which implies that
those models can be realized at low energy scales and, in particular, even at
the electroweak scale. So that, being that symmetries realized in Nature, new
physics may be really just around the corner.Comment: 10 pages, version to be published in Physics Letters
Developing independent investigators for clinical research relevant for Africa
Sustainable research capacity building requires training individuals at multiple levels within a supportive institutional infrastructure to develop a critical mass of independent researchers. At many African medical institutions, a PhD is important for academic promotion and is, therefore, an important focal area for capacity building programs. We examine the training at the Infectious Diseases Institute (IDI) as a model for in-country training based on systems capacity building and attention to the academic environment. PhD training in Africa should provide a strong research foundation for individuals to perform independent, original research and to mentor others. Training the next generation of researchers within excellent indigenous academic centers of excellence with strong institutional infrastructure will empower trainees to ask regionally relevant research questions that will benefit Africans
The impact on nurses and nurse managers of introducing PEPFAR clinical services in urban government clinics in Uganda
BACKGROUND: Improving provider performance is central to strengthening health services in developing countries. Because of critical shortages of physicians, many clinics in sub-Saharan Africa are led by nurses. In addition to clinical skills, nurse managers need practical managerial skills and adequate resources to ensure procurement of essential supplies, quality assurance implementation, and productive work environment. Giving nurses more autonomy in their work empowers them in the workplace and has shown to create positive influence on work attitudes and behaviors. The Infectious Disease Institute, an affiliate of Makerere University College of Health Science, in an effort to expand the needed HIV services in the Ugandan capital, established a community-university partnership with the Ministry of Health to implement an innovative model to build capacity in HIV service delivery. This paper evaluates the impact on the nurses from this innovative program to provide more health care in six nurse managed Kampala City Council (KCC) Clinics. METHODS: A mixed method approach was used. The descriptive study collected key informant interviews from the six nurse managers, and administered a questionnaire to 20 staff nurses between September and December 2009. Key themes were manually identified from the interviews, and the questionnaire data were analyzed using SPSS. RESULTS: Introducing new HIV services into six KCC clinics was positive for the nurses. They identified the project as successful because of perceived improved environment, increase in useful in-service training, new competence to manage patients and staff, improved physical infrastructure, provision of more direct patient care, motivation to improve the clinic because the project acted on their suggestions, and involvement in role expansion. All of these helped empower the nurses, improving quality of care and increasing job satisfaction. CONCLUSIONS: This community-university HIV innovative model was successful from the point of view of the nurses and nurse managers. This model shows promise in increasing effective, quality health service; HIV and other programs can build capacity and empower nurses and nurse managers to directly implement such services. It also demonstrates how MakCHS can be instrumental through partnerships in designing and testing effective strategies, building human health resources and improving Ugandan health outcomes
Search for the rare decays and
A search for the rare decay of a or meson into the final
state is performed, using data collected by the LHCb experiment
in collisions at and TeV, corresponding to an integrated
luminosity of 3 fb. The observed number of signal candidates is
consistent with a background-only hypothesis. Branching fraction values larger
than for the decay mode are
excluded at 90% confidence level. For the decay
mode, branching fraction values larger than are excluded at
90% confidence level, this is the first branching fraction limit for this
decay.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-2015-044.htm
Study of the production of and hadrons in collisions and first measurement of the branching fraction
The product of the () differential production
cross-section and the branching fraction of the decay () is
measured as a function of the beauty hadron transverse momentum, ,
and rapidity, . The kinematic region of the measurements is and . The measurements use a data sample
corresponding to an integrated luminosity of collected by the
LHCb detector in collisions at centre-of-mass energies in 2011 and in 2012. Based on previous LHCb
results of the fragmentation fraction ratio, , the
branching fraction of the decay is
measured to be \begin{equation*} \mathcal{B}(\Lambda_b^0\rightarrow J/\psi
pK^-)= (3.17\pm0.04\pm0.07\pm0.34^{+0.45}_{-0.28})\times10^{-4},
\end{equation*} where the first uncertainty is statistical, the second is
systematic, the third is due to the uncertainty on the branching fraction of
the decay , and the
fourth is due to the knowledge of . The sum of the
asymmetries in the production and decay between and
is also measured as a function of and .
The previously published branching fraction of , relative to that of , is updated.
The branching fractions of are determined.Comment: 29 pages, 19figures. 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-2015-032.htm
Evidence for the strangeness-changing weak decay
Using a collision data sample corresponding to an integrated luminosity
of 3.0~fb, collected by the LHCb detector, we present the first search
for the strangeness-changing weak decay . No
hadron decay of this type has been seen before. A signal for this decay,
corresponding to a significance of 3.2 standard deviations, is reported. The
relative rate is measured to be
, where and
are the and fragmentation
fractions, and is the branching
fraction. Assuming is bounded between 0.1 and
0.3, the branching fraction would lie
in the range from to .Comment: 7 pages, 2 figures, 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-2015-047.htm
Measurements of long-range near-side angular correlations in TeV proton-lead collisions in the forward region
Two-particle angular correlations are studied in proton-lead collisions at a
nucleon-nucleon centre-of-mass energy of TeV, collected
with the LHCb detector at the LHC. The analysis is based on data recorded in
two beam configurations, in which either the direction of the proton or that of
the lead ion is analysed. The correlations are measured in the laboratory
system as a function of relative pseudorapidity, , and relative
azimuthal angle, , for events in different classes of event
activity and for different bins of particle transverse momentum. In
high-activity events a long-range correlation on the near side, , is observed in the pseudorapidity range . This
measurement of long-range correlations on the near side in proton-lead
collisions extends previous observations into the forward region up to
. The correlation increases with growing event activity and is found
to be more pronounced in the direction of the lead beam. However, the
correlation in the direction of the lead and proton beams are found to be
compatible when comparing events with similar absolute activity in the
direction analysed.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-2015-040.htm
The Complete Genome of Teredinibacter turnerae T7901: An Intracellular Endosymbiont of Marine Wood-Boring Bivalves (Shipworms)
Here we report the complete genome sequence of Teredinibacter turnerae T7901. T. turnerae is a marine gamma proteobacterium that occurs as an intracellular endosymbiont in the gills of wood-boring marine bivalves of the family Teredinidae (shipworms). This species is the sole cultivated member of an endosymbiotic consortium thought to provide the host with enzymes, including cellulases and nitrogenase, critical for digestion of wood and supplementation of the host's nitrogen-deficient diet. T. turnerae is closely related to the free-living marine polysaccharide degrading bacterium Saccharophagus degradans str. 2–40 and to as yet uncultivated endosymbionts with which it coexists in shipworm cells. Like S. degradans, the T. turnerae genome encodes a large number of enzymes predicted to be involved in complex polysaccharide degradation (>100). However, unlike S. degradans, which degrades a broad spectrum (>10 classes) of complex plant, fungal and algal polysaccharides, T. turnerae primarily encodes enzymes associated with deconstruction of terrestrial woody plant material. Also unlike S. degradans and many other eubacteria, T. turnerae dedicates a large proportion of its genome to genes predicted to function in secondary metabolism. Despite its intracellular niche, the T. turnerae genome lacks many features associated with obligate intracellular existence (e.g. reduced genome size, reduced %G+C, loss of genes of core metabolism) and displays evidence of adaptations common to free-living bacteria (e.g. defense against bacteriophage infection). These results suggest that T. turnerae is likely a facultative intracellular ensosymbiont whose niche presently includes, or recently included, free-living existence. As such, the T. turnerae genome provides insights into the range of genomic adaptations associated with intracellular endosymbiosis as well as enzymatic mechanisms relevant to the recycling of plant materials in marine environments and the production of cellulose-derived biofuels
- …