9,269 research outputs found
Fluctuations in a coupled-oscillator model of the cardiovascular system
We present a model of the cardiovascular system (CVS) based on a system of coupled oscillators. Using this approach we can describe several complex physiological phenomena that can have a range of applications. For instance, heart rate variability (HRV), can have a new deterministic explanation. The intrinsic dynamics of the HRV is controlled by deterministic couplings between the physiological oscillators in our model and without the need to introduce external noise as is commonly done. This new result provides potential applications not only for physiological systems but also for the design of very precise electronic generators where the frequency stability is crucial. Another important phenomenon is that of oscillation death. We show that in our CVS model the mechanism leading to the quenching of the oscillations can be controlled, not only by the coupling parameter, but by a more general scheme. In fact, we propose that a change in the relative current state of the cardiovascular oscillators can lead to a cease of the oscillations without actually changing the strength of the coupling among them. We performed real experiments using electronic oscillators and show them to match the theoretical and numerical predictions. We discuss the relevance of the studied phenomena to real cardiovascular systems regimes, including the explanation of certain pathologies, and the possible applications in medical practice
A system of three transiting super-Earths in a cool dwarf star
We present the detection of three super-Earths transiting the cool star
LP415-17, monitored by K2 mission in its 13th campaign. High resolution spectra
obtained with HARPS-N/TNG showed that the star is a mid-late K dwarf. Using
spectral synthesis models we infer its effective temperature, surface gravity
and metallicity and subse- quently determined from evolutionary models a
stellar radius of 0.58 R Sun. The planets have radii of 1.8, 2.6 and 1.9 R
Earth and orbital periods of 6.34, 13.85 and 40.72 days. High resolution images
discard any significant contamination by an intervening star in the line of
sight. The orbit of the furthest planet has radius of 0.18 AU, close to the
inner edge of the habitable zone. The system is suitable to improve our
understanding of formation and dynamical evolution of super-Earth systems in
the rocky - gaseous threshold, their atmospheres, internal structure,
composition and interactions with host stars.Comment: Accepted for publication in MNRAS Letter
Abundance trend with condensation temperature for stars with different Galactic birth places
During the past decade, several studies reported a correlation between
chemical abundances of stars and condensation temperature (also known as Tc
trend). However, the real astrophysical nature of this correlation is still
debated. The main goal of this work is to explore the possible dependence of
the Tc trend on stellar Galactocentric distances, Rmean. We used high-quality
spectra of about 40 stars observed with the HARPS and UVES spectrographs to
derive precise stellar parameters, chemical abundances, and stellar ages. A
differential line-by-line analysis was applied to achieve the highest possible
precision in the chemical abundances. We confirm previous results that [X/Fe]
abundance ratios depend on stellar age and that for a given age, some elements
also show a dependence on Rmean. When using the whole sample of stars, we
observe a weak hint that the Tc trend depends on Rmean. The observed dependence
is very complex and disappears when only stars with similar ages are
considered. To conclude on the possible dependence of the Tc trend on the
formation place of stars, a larger sample of stars with very similar
atmospheric parameters and stellar ages observed at different Galactocentric
distances is neededComment: Accepted by A&
Rapid Phenotype-Driven Gene Sequencing with the NeoSeq Panel: A Diagnostic Tool for Critically Ill Newborns with Suspected Genetic Disease
New genomic sequencing techniques have shown considerable promise in the field of neonatology, increasing the diagnostic rate and reducing time to diagnosis. However, several obstacles have hindered the incorporation of this technology into routine clinical practice. We prospectively evaluated the diagnostic rate and diagnostic turnaround time achieved in newborns with suspected genetic diseases using a rapid phenotype-driven gene panel (NeoSeq) containing 1870 genes implicated in congenital malformations and neurological and metabolic disorders of early onset (<2 months of age). Of the 33 newborns recruited, a genomic diagnosis was established for 13 (39.4%) patients (median diagnostic turnaround time, 7.5 days), resulting in clinical management changes in 10 (76.9%) patients. An analysis of 12 previous prospective massive sequencing studies (whole genome (WGS), whole exome (WES), and clinical exome (CES) sequencing) in newborns admitted to neonatal intensive care units (NICUs) with suspected genetic disorders revealed a comparable median diagnostic rate (37.2%), but a higher median diagnostic turnaround time (22.3 days) than that obtained with NeoSeq. Our phenotype-driven gene panel, which is specific for genetic diseases in critically ill newborns is an affordable alternative to WGS and WES that offers comparable diagnostic efficacy, supporting its implementation as a first-tier genetic test in NICUs
Dimensions of Religiousness and Cancer Screening Behaviors among Church-Going Latinas
Churches are a promising setting through which to reach Latinas with cancer control efforts. A better understanding of the dimensions of religiousness that impact health behaviors could inform efforts to tailor cancer control programs for this setting. The purpose of this study was to explore relationships between dimensions of religiousness with adherence to cancer screening recommendations among church-going Latinas. Female Spanish-speaking members, aged 18 and older from a Baptist church in Boston, Massachusetts (N = 78), were interviewed about cancer screening behaviors and dimensions of religiousness. We examined adherence to individual cancer screening tests (mammography, Pap test, and colonoscopy), as well as adherence to all screening tests for which participants were age-eligible. Dimensions of religiousness assessed included church participation, religious support, active and passive spiritual health locus of control, and positive and negative religious coping. Results showed that roughly half (46 %) of the sample had not received all of the cancer screening tests for which they were age-eligible. In multivariate analyses, positive religious coping was significantly associated with adherence to all age-appropriate screening (OR = 5.30, p \u3c .01). Additional research is warranted to replicate these results in larger, more representative samples and to examine the extent to which enhancement of religious coping could increase the impact of cancer control interventions for Latinas
Barred-beach morphological control on infragravity motion
A conceptual analysis of the coupling between bars and infragravity waves is performed combining laboratory experiments and numerical modeling. Experiments are carried out in a wave flume with a barred profile. The Boussinesq fully-nonlinear model SERR1D is validated with the laboratory data and a sensitivity analysis is performed next to study the influence on the infragravity wave dynamics of bar amplitude and location, and swash zone slope. A novel technique of incident and reflected motions separation that conserves temporal characteristics is applied. We observe that changing bar characteristics induces substantial variations in trapped energy. Interestingly, a modification of swash zone slope has a large influence on the reflected component, controlling amplitude and phase time-lag, and consequently on the resonant pattern. Variations of trapped infragravity energy induced by changes of swash zone slope reach 25 %. These changes in infragravity pattern consequently affect short-wave dynamics by modifying the breakpoint location and the breaking intensity. Our conceptual investigation suggests the existence of a morphological feedback through the action of evolving morphology on infragravity structures which modulates the action of short-waves on the morphology itself
Response to HAART according to sex and origin (immigrant vs autochthonous) in a cohort of patients who initiate antiretroviral treatment
Pedunculopontine arousal system physiology—Effects of psychostimulant abuse
This review describes the interactions between the pedunculopontine nucleus (PPN), the ventral tegmental area (VTA), and the thalamocortical system. Experiments using modulators of cholinergic receptors in the PPN clarified its role on psychostimulant-induced locomotion. PPN activation was found to be involved in the animal?s voluntary search for psychostimulants. Every PPN neuron is known to generate gamma band oscillations. Voltage-gated calcium channels are key elements in the generation and maintenance of gamma band activity of PPN neurons. Calcium channels are also key elements mediating psychostimulant-induced alterations in the thalamic targets of PPN output. Thus, the PPN is a key substrate for maintaining arousal and REM sleep, but also in modulating psychostimulant self-administrationFil: Urbano Suarez, Francisco Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Bisagno, Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas (i); ArgentinaFil: Gonzalez, Betina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas (i); ArgentinaFil: Rivero Echeto, Maria Celeste Solange. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Muñiz, Javier A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas (i); ArgentinaFil: Luster, Brennon. University Of Arkansas For Medical Sciences; Estados UnidosFil: D'onofrio, Stasia. University Of Arkansas For Medical Sciences; Estados UnidosFil: Mahaffey, Susan. University Of Arkansas For Medical Sciences; Estados UnidosFil: Garcia Rill, E. University Of Arkansas For Medical Sciences; Estados Unido
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