1,497 research outputs found
Nonlinear dynamics of Bose-condensed gases by means of a low- to high-density variational approach
We propose a versatile variational method to investigate the spatio-temporal
dynamics of one-dimensional magnetically-trapped Bose-condensed gases. To this
end we employ a \emph{q}-Gaussian trial wave-function that interpolates between
the low- and the high-density limit of the ground state of a Bose-condensed
gas. Our main result consists of reducing the Gross-Pitaevskii equation, a
nonlinear partial differential equation describing the T=0 dynamics of the
condensate, to a set of only three equations: \emph{two coupled nonlinear
ordinary differential equations} describing the phase and the curvature of the
wave-function and \emph{a separate algebraic equation} yielding the generalized
width. Our equations recover those of the usual Gaussian variational approach
(in the low-density regime), and the hydrodynamic equations that describe the
high-density regime. Finally, we show a detailed comparison between the
numerical results of our equations and those of the original Gross-Pitaevskii
equation.Comment: 11 pages, 12 figures, submitted to Phys. Rev. A, January 200
11-Deoxycorticosterone Producing Adrenal Hyperplasia as a Very Unusual Cause of Endocrine Hypertension: Case Report and Systematic Review of the Literature
Background and Objectives: 11-deoxycorticosterone overproduction due to an adrenal tumor or hyperplasia is a very rare cause of mineralocorticoid-induced hypertension. The objective is to provide the most relevant clinical features that clinicians dealing with patients presenting with the hallmarks of hypertension due to 11-deoxycorticosterone-producing adrenal lesions should be aware of. Design and Methods: We report the case of a patient with an 11-deoxycorticosterone-producing adrenal lesion and provide a systematic review of all published cases (PubMed, Web of Science and EMBASE) between 1965 and 2021. Results: We identified 46 cases (including ours). Most cases (31, 67%) affected women with a mean age of 42.9 +/- 15.2 years and presented with high blood pressure and hypokalemia (average of 2.68 +/- 0.62 mmol/L). Median (interquartile range) time from onset of first suggestive symptoms to diagnosis was 24 (55) months. Aldosterone levels were low or in the reference range in 98% of the cases when available. 11-deoxycorticosterone levels were a median of 12.5 (18.9) times above the upper limit of the normal reference range reported in each article and overproduction of more than one hormone was seen in 31 (67%). Carcinoma was the most common histological type (21, 45.7%). Median tumor size was 61.5 (60) mm. Malignant lesions were larger, had higher 11-deoxycorticosterone levels and shorter time of evolution at diagnosis compared to benign lesions. Conclusion: 11-deoxycorticosterone-producing adrenal lesions are very rare, affecting mostly middle-aged women with a primary aldosteronism-like clinical presentation and carcinoma is the most frequent histological diagnosis. Measuring 11-deoxycorticosterone levels, when low aldosterone levels or in the lower limit of the reference range are present in hypertensive patients, is advisable. Systematic Review Registration:Open Science Framework, 10.17605/OSF.IO/NR7UV
Atom--Molecule Coherence in a Bose-Einstein Condensate
Coherent coupling between atoms and molecules in a Bose-Einstein condensate
(BEC) has been observed. Oscillations between atomic and molecular states were
excited by sudden changes in the magnetic field near a Feshbach resonance and
persisted for many periods of the oscillation. The oscillation frequency was
measured over a large range of magnetic fields and is in excellent quantitative
agreement with the energy difference between the colliding atom threshold
energy and the energy of the bound molecular state. This agreement indicates
that we have created a quantum superposition of atoms and diatomic molecules,
which are chemically different species.Comment: 7 pages, 6 figure
PP1 promotes cyclin B destruction and the metaphase–anaphase transition by dephosphorylating CDC20
Ubiquitin-dependent proteolysis of cyclin B and securin initiates sister chromatid segregation and anaphase. The anaphase-promoting complex/cyclosome and its coactivator CDC20 (APC/CCDC20) form the main ubiquitin E3 ligase for these two proteins. APC/CCDC20 is regulated by CDK1-cyclin B and counteracting PP1 and PP2A family phosphatases through modulation of both activating and inhibitory phosphorylation. Here, we report that PP1 promotes cyclin B destruction at the onset of anaphase by removing specific inhibitory phosphorylation in the N-terminus of CDC20. Depletion or chemical inhibition of PP1 stabilizes cyclin B and results in a pronounced delay at the metaphase-to-anaphase transition after chromosome alignment. This requirement for PP1 is lost in cells expressing CDK1 phosphorylation–defective CDC206A mutants. These CDC206A cells show a normal spindle checkpoint response and rapidly destroy cyclin B once all chromosomes have aligned and enter into anaphase in the absence of PP1 activity. PP1 therefore facilitates the metaphase-to-anaphase transition by promoting APC/CCDC20-dependent destruction of cyclin B in human cells
A computational model of open-irrigated radiofrequency catheter ablation accounting for mechanical properties of the cardiac tissue
Radiofrequency catheter ablation (RFCA) is an effective treatment for cardiac arrhythmias. Although generally safe, it is not completely exempt from the risk of complications. The great flexibility of computational models can be a major asset in optimizing interventional strategies, if they can produce sufficiently precise estimations of the generated lesion for a given ablation protocol. This requires an accurate description of the catheter tip and the cardiac tissue. In particular, the deformation of the tissue under the catheter pressure during the ablation is an important aspect that is overlooked in the existing literature, that resorts to a sharp insertion of the catheter into an undeformed geometry. As the lesion size depends on the power dissipated in the tissue, and the latter depends on the percentage of the electrode surface in contact with the tissue itself, the sharp insertion geometry has the tendency to overestimate the lesion obtained, especially when a larger force is applied to the catheter. In this paper we introduce a full 3D computational model that takes into account the tissue elasticity, and is able to capture the tissue deformation and realistic power dissipation in the tissue. Numerical results in FEniCS-HPC are provided to validate the model against experimental data, and to compare the lesions obtained with the new model and with the classical ones featuring a sharp electrode insertion in the tissue.La Caixa 2016 PhD grant to M. Leoni, and Abbott non-conditional grant to J.M. Guerra Ramo
Evaluation of dengue fever reports during an epidemic, Colombia
OBJECTIVE To assess the validity of dengue fever reports and how they relate to the definition of case and severity. METHODS Diagnostic test assessment was conducted using cross-sectional sampling from a universe of 13,873 patients treated during the fifth epidemiological period in health institutions from 11 Colombian departments in 2013. The test under analyses was the reporting to the National Public Health Surveillance System, and the reference standard was the review of histories identified by active institutional search. We reviewed all histories of patients diagnosed with dengue fever, as well as a random sample of patients with febrile syndromes. The specificity and sensitivity of reports were estimated for this purpose, considering the inverse of the probability of being selected for weighting. The concordance between reporting and the findings of the active institutional search was calculated using Kappa statistics. RESULTS We included 4,359 febrile patients, and 31.7% were classified as compatible with dengue fever (17 with severe dengue fever; 461 with dengue fever and warning signs; 904 with dengue fever and no warning signs). The global sensitivity of reports was 13.2% (95%CI 10.9;15.4) and specificity was 98.4% (95%CI 97.9;98.9). Sensitivity varied according to severity: 12.1% (95%CI 9.3;14.8) for patients presenting dengue fever with no warning signs; 14.5% (95%CI 10.6;18.4) for those presenting dengue fever with warning signs, and 40.0% (95%CI 9.6;70.4) for those with severe dengue fever. Concordance between reporting and the findings of the active institutional search resulted in a Kappa of 10.1%. CONCLUSIONS Low concordance was observed between reporting and the review of clinical histories, which was associated with the low reporting of dengue fever compatible cases, especially milder cases
Star-forming cores embedded in a massive cold clump: Fragmentation, collapse and energetic outflows
The fate of massive cold clumps, their internal structure and collapse need
to be characterised to understand the initial conditions for the formation of
high-mass stars, stellar systems, and the origin of associations and clusters.
We explore the onset of star formation in the 75 M_sun SMM1 clump in the region
ISOSS J18364-0221 using infrared and (sub-)millimetre observations including
interferometry. This contracting clump has fragmented into two compact cores
SMM1 North and South of 0.05 pc radius, having masses of 15 and 10 M_sun, and
luminosities of 20 and 180 L_sun. SMM1 South harbours a source traced at 24 and
70um, drives an energetic molecular outflow, and appears supersonically
turbulent at the core centre. SMM1 North has no infrared counterparts and shows
lower levels of turbulence, but also drives an outflow. Both outflows appear
collimated and parsec-scale near-infrared features probably trace the
outflow-powering jets. We derived mass outflow rates of at least 4E-5 M_sun/yr
and outflow timescales of less than 1E4 yr. Our HCN(1-0) modelling for SMM1
South yielded an infall velocity of 0.14 km/s and an estimated mass infall rate
of 3E-5 M_sun/yr. Both cores may harbour seeds of intermediate- or high-mass
stars. We compare the derived core properties with recent simulations of
massive core collapse. They are consistent with the very early stages dominated
by accretion luminosity.Comment: Accepted for publication in ApJ, 14 pages, 7 figure
Evaluation of the efficacy and safety of text messages targeting adherence to cardiovascular medications in secondary prevention: the txt2heart Colombia randomised controlled trial (Preprint)
Background:
Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of mortality in the world. Prevalence is estimated at around 100 million patients worldwide. There is evidence that antiplatelet agents and antihypertensive medication reduce the risk of new vascular events in this population, but treatment adherence is very low.
Objective:
We developed an intervention based on behavioral modification techniques delivered via mobile short message services (SMS) to increase the adherence to pharmacologic treatment on patients with prior history of ASCVD.
Methods:
We conducted a randomized controlled clinical trial for patients with a prior diagnosis of cardiovascular event such as acute myocardial infarction, unstable angina, cerebrovascular disease or peripheral artery disease in one centre in Colombia. Patients randomized to the intervention arm were assigned to receive SMS daily for the first 4 weeks, five SMS on week 5: three SMS per week from week 6, and one SMS from 8th week until 52nd week. Patients in the control arm received a monthly SMS reminding them of the next study appointment, requesting information about changes in phone number, thanking them for participating in the study and reminding them of the importance of the study. Primary endpoint was change in Low Density Lipoprotein-Cholesterol (LDL-C) and the secondary endpoints were change in thromboxane B2 levels, heart rate, systolic and diastolic blood pressure. Medication adherence was measured with the Medication Adherence Report Scale (MARS 5), mortality and new cardiac hospitalization were assessed at one year end point. A logistic regression analysis and bivariate testing was performed.
Results:
Nine hundred and thirty patients were randomized, 805 (87%) completed follow up, and were analyzed for the primary endpoint. There was no difference between arms in change of LDL-C at 12 months (P=.41). or for any of the secondary outcomes. No adverse events were reported.
Conclusions:
In our study we did not find evidence that a behavior modification intervention delivered by SMS improved LDL-C, blood pressure levels or adherence at 12 months. More research is needed to evaluate whether different SMS strategies including personalized messages and with different timing are effective; future studies should include mixed methods to understand better why, for whom and in which context (e.g. health system, social environment) SMS interventions work (or not) to improve adherence in patients with ASCVD. Clinical Trial: Clinicaltrial.gov NCT03098186. Date of registration: March 31st 201
- …