1,115 research outputs found
Long-term results between interval surgery and follow-up after percutaneous cholecystostomy: a retrospective cohort study
Introduction:
Although cholecystectomy is the treatment of choice for acute cholecystitis (AC), in patients with high surgical risk percutaneous cholecystostomy (PC) is chosen in some cases. The aim of this report is to follow up these patients and evaluate biliary recurrences after PC.
Methods:
A descriptive retrospective study was carried out in a third level hospital from August 2005 to December 2014. All patients diagnosed with acute lithiasis cholecystitis who were indicated as initial treatment with antibiotic therapy and PC echo-guided were included. Patients requiring emergent cholecystectomy during hospital and those who died during the AC episode were excluded. After hospital discharge, the patients were divided into two groups group 1 (interval cholecystectomy) and group 2 (no surgery).
Results:
From the 86 healed patients, there were 8 losses in the follow-up, so 78 patients were analyzed group 1 (n = 12) and group 2 (n = 66
Interaction Between Convection and Pulsation
This article reviews our current understanding of modelling convection
dynamics in stars. Several semi-analytical time-dependent convection models
have been proposed for pulsating one-dimensional stellar structures with
different formulations for how the convective turbulent velocity field couples
with the global stellar oscillations. In this review we put emphasis on two,
widely used, time-dependent convection formulations for estimating pulsation
properties in one-dimensional stellar models. Applications to pulsating stars
are presented with results for oscillation properties, such as the effects of
convection dynamics on the oscillation frequencies, or the stability of
pulsation modes, in classical pulsators and in stars supporting solar-type
oscillations.Comment: Invited review article for Living Reviews in Solar Physics. 88 pages,
14 figure
TEAD and YAP regulate the enhancer network of human embryonic pancreatic progenitors.
The genomic regulatory programmes that underlie human organogenesis are poorly understood. Pancreas development, in particular, has pivotal implications for pancreatic regeneration, cancer and diabetes. We have now characterized the regulatory landscape of embryonic multipotent progenitor cells that give rise to all pancreatic epithelial lineages. Using human embryonic pancreas and embryonic-stem-cell-derived progenitors we identify stage-specific transcripts and associated enhancers, many of which are co-occupied by transcription factors that are essential for pancreas development. We further show that TEAD1, a Hippo signalling effector, is an integral component of the transcription factor combinatorial code of pancreatic progenitor enhancers. TEAD and its coactivator YAP activate key pancreatic signalling mediators and transcription factors, and regulate the expansion of pancreatic progenitors. This work therefore uncovers a central role for TEAD and YAP as signal-responsive regulators of multipotent pancreatic progenitors, and provides a resource for the study of embryonic development of the human pancreas
Techniques for temporal detection of neural sensitivity to external stimulation
We propose a simple measure of neural sensitivity for characterizing stimulus coding. Sensitivity is defined as the fraction of neurons that show positive responses to n stimuli out of a total of N. To determine a positive response, we propose two methods: Fisherian statistical testing and a data-driven Bayesian approach to determine the response probability of a neuron. The latter is non-parametric, data-driven, and captures a lower bound for the probability of neural responses to sensory stimulation. Both methods are compared with a standard test that assumes normal probability distributions. We applied the sensitivity estimation based on the proposed method to experimental data recorded from the mushroom body (MB) of locusts. We show that there is a broad range of sensitivity that the MB response sweeps during odor stimulation. The neurons are initially tuned to specific odors, but tend to demonstrate a generalist behavior towards the end of the stimulus period, meaning that the emphasis shifts from discrimination to feature learning
A mathematical and computational review of Hartree-Fock SCF methods in Quantum Chemistry
We present here a review of the fundamental topics of Hartree-Fock theory in
Quantum Chemistry. From the molecular Hamiltonian, using and discussing the
Born-Oppenheimer approximation, we arrive to the Hartree and Hartree-Fock
equations for the electronic problem. Special emphasis is placed in the most
relevant mathematical aspects of the theoretical derivation of the final
equations, as well as in the results regarding the existence and uniqueness of
their solutions. All Hartree-Fock versions with different spin restrictions are
systematically extracted from the general case, thus providing a unifying
framework. Then, the discretization of the one-electron orbitals space is
reviewed and the Roothaan-Hall formalism introduced. This leads to a exposition
of the basic underlying concepts related to the construction and selection of
Gaussian basis sets, focusing in algorithmic efficiency issues. Finally, we
close the review with a section in which the most relevant modern developments
(specially those related to the design of linear-scaling methods) are commented
and linked to the issues discussed. The whole work is intentionally
introductory and rather self-contained, so that it may be useful for non
experts that aim to use quantum chemical methods in interdisciplinary
applications. Moreover, much material that is found scattered in the literature
has been put together here to facilitate comprehension and to serve as a handy
reference.Comment: 64 pages, 3 figures, tMPH2e.cls style file, doublesp, mathbbol and
subeqn package
The implementation evaluation of primary care groups of practice: a focus on organizational identity
<p>Abstract</p> <p>Background</p> <p>Since 2002 the Health Ministry of Québec (Canada) has been implementing a primary care organizational innovation called 'family medicine groups'. This is occurring in a political context in which the reorganization of primary care is considered necessary to improve health care system performance. More specifically, the purpose of this reform has been to overcome systemic deficiencies in terms of accessibility and continuity of care. This paper examines the first years of implementation of the family medicine group program, with a focus on the emergence of the organizational identity of one of the pilot groups located in the urban area of Montreal.</p> <p>Methods</p> <p>An in-depth longitudinal case study was conducted over two and a half years. Face to face individual interviews with key informants from the family medicine group under study were conducted over the research period considered. Data was gathered throuhg observations and documentary analysis. The data was analyzed using temporal bracketing and Fairclough's three-dimensional critical discourse analytical techniques.</p> <p>Results</p> <p>Three different phases were identified over the period under study. During the first phase, which corresponded to the official start-up of the family medicine group program, new resources and staff were only available at the end of the period, and no changes occurred in medical practices. Power struggles between physicians and nurses characterized the second phase, resulting in a very difficult integration of advanced nurse practitioners into the group. Indeed, the last phase was portrayed by initial collaborative practices associated with a sensegiving process prompted by a new family medicine group director.</p> <p>Conclusions</p> <p>The creation of a primary care team is a very challenging process that goes beyond the normative policy definitions of who is on the team or what the team has to do. To fulfil expectations of quality improvement through team-based care, health care professionals who are required to work together need shared time/space contexts to communicate; to overcome interprofessional and interpersonal conflicts; and to make sense of and define who they collectively are and what they do as a clinical team.</p
The Evolution of Compact Binary Star Systems
We review the formation and evolution of compact binary stars consisting of
white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and
BHs are thought to be the primary astrophysical sources of gravitational waves
(GWs) within the frequency band of ground-based detectors, while compact
binaries of WDs are important sources of GWs at lower frequencies to be covered
by space interferometers (LISA). Major uncertainties in the current
understanding of properties of NSs and BHs most relevant to the GW studies are
discussed, including the treatment of the natal kicks which compact stellar
remnants acquire during the core collapse of massive stars and the common
envelope phase of binary evolution. We discuss the coalescence rates of binary
NSs and BHs and prospects for their detections, the formation and evolution of
binary WDs and their observational manifestations. Special attention is given
to AM CVn-stars -- compact binaries in which the Roche lobe is filled by
another WD or a low-mass partially degenerate helium-star, as these stars are
thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure
Foundations of Black Hole Accretion Disk Theory
This review covers the main aspects of black hole accretion disk theory. We
begin with the view that one of the main goals of the theory is to better
understand the nature of black holes themselves. In this light we discuss how
accretion disks might reveal some of the unique signatures of strong gravity:
the event horizon, the innermost stable circular orbit, and the ergosphere. We
then review, from a first-principles perspective, the physical processes at
play in accretion disks. This leads us to the four primary accretion disk
models that we review: Polish doughnuts (thick disks), Shakura-Sunyaev (thin)
disks, slim disks, and advection-dominated accretion flows (ADAFs). After
presenting the models we discuss issues of stability, oscillations, and jets.
Following our review of the analytic work, we take a parallel approach in
reviewing numerical studies of black hole accretion disks. We finish with a few
select applications that highlight particular astrophysical applications:
measurements of black hole mass and spin, black hole vs. neutron star accretion
disks, black hole accretion disk spectral states, and quasi-periodic
oscillations (QPOs).Comment: 91 pages, 23 figures, final published version available at
http://www.livingreviews.org/lrr-2013-
Men and Women Exhibit a Differential Bias for Processing Movement versus Objects
Sex differences in many spatial and verbal tasks appear to reflect an inherent low-level processing bias for movement in males and objects in females. We explored this potential movement/object bias in men and women using a computer task that measured targeting performance and/or color recognition. The targeting task showed a ball moving vertically towards a horizontal line. Before reaching the line, the ball disappeared behind a masking screen, requiring the participant to imagine the movement vector and identify the intersection point. For the color recognition task, the ball briefly changed color before disappearing beneath the mask and participants were required only to identify the color shade. Results showed that targeting accuracy for slow and fast moving balls was significantly better in males compared to females. No sex difference was observed for color shade recognition. We also studied a third, dual attention task comprised of the first two, where the moving ball briefly changed color randomly just before passing beneath the masking screen. When the ball changed color, participants were required only to identify the color shade. If the ball didn't change color, participants estimated the intersection point. Participants in this dual attention condition were first tested with the targeting and color tasks alone and showed results that were similar to the previous groups tested on a single task. However, under the dual attention condition, male accuracy in targeting, as well as color shade recognition, declined significantly compared to their performance when the tasks were tested alone. No significant changes were found in female performance. Finally, reaction times for targeting and color choices in both sexes correlated highly with ball speed, but not accuracy. Overall, these results provide evidence of a sex-related bias in processing objects versus movement, which may reflect sex differences in bottom up versus top-down analytical strategies
Modeling a mobile group recommender system for tourism with intelligent agents and gamification
To provide recommendations to groups of people is a complex task, especially due to the groupâs heterogeneity and conflicting preferences and personalities. This heterogeneity is even deeper in occasional groups formed for predefined tour packages in tourism. Group Recommender Systems (GRS) are being designed for helping in situations like those. However, many limitations can still be found, either on their time-consuming configurations and excessive intrusiveness to build the touristsâ profile, or in their lack of concern for the touristsâ interests during the planning and tours, like feeling a greater liberty, diminish the sense of fear/being lost, increase their sense of companionship, and promote the social interaction among them without losing a personalized experience. In this paper, we propose a conceptual model that intends to enhance GRS for tourism by using gamification techniques, intelligent agents modeled with the touristsâ context and profile, such as psychological and socio-cultural aspects, and dialogue games between the agents for the post-recommendation process. Some important aspects of a GRS for tourism are also discussed, opening the way for the proposed conceptual model, which we believe will help to solve the identified limitations.This work was supported by the GrouPlanner Project (POCI-01-0145-FEDER-29178) and by National Funds through the FCT âFundação para a CiĂȘncia e a Tecnologia (Portuguese Foundation for Science and Technology) within the Projects UID/CEC/00319/2019 and UID/EEA/00760/2019
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