3,674 research outputs found
Temporal profile and mechanisms of the prompt sympathoexcitation following coronary ligation in Wistar rats
Our aim was to assess the timing and mechanisms of the sympathoexcitation that occurs immediately after coronary ligation. We recorded thoracic sympathetic (tSNA) and phrenic activities, heart rate (HR) and perfusion pressure in Wistar rats subjected to either ligation of the left anterior descending coronary artery (LAD) or Sham operated in the working heart-brainstem preparation. Thirty minutes after LAD ligation, tSNA had increased (basal: 2.5±0.2 µV, 30 min: 3.5±0.3 µV), being even higher at 60 min (5.2±0.5 µV, P<0.01); while no change was observed in Sham animals. HR increased significantly 45 min after LAD (P<0.01). Sixty minutes after LAD ligation, there was: (i) an augmented peripheral chemoreflex - greater sympathoexcitatory response (50, 45 and 27% of increase to 25, 50 and 75 µL injections of NaCN 0.03%, respectively, when compared to Sham, P<0.01); (ii) an elevated pressor response (32±1 versus 23±1 mmHg in Sham, P<0.01) and a reduced baroreflex sympathetic gain (1.3±0.1 versus Sham 2.0±0.1%.mmHg-1, P<0.01) to phenylephrine injection; (iii) an elevated cardiac sympathetic tone (ΔHR after atenolol: -108±8 versus -82±7 bpm in Sham, P<0.05). In contrast, no changes were observed in cardiac vagal tone and bradycardic response to both baroreflex and chemoreflex between LAD and Sham groups. The immediate sympathoexcitatory response in LAD rats was dependent on an excitatory spinal sympathetic cardiocardiac reflex, whereas at 3 h an angiotensin II type 1 receptor mechanism was essential since Losartan curbed the response by 34% relative to LAD rats administered saline (P<0.05). A spinal reflex appears key to the immediate sympathoexcitatory response after coronary ligation. Therefore, the sympathoexcitatory response seems to be maintained by an angiotensinergic mechanism and concomitant augmentation of sympathoexcitatory reflexes
Metal-Insulator transition in the Generalized Hubbard model
We present the exact ground-state wave function and energy of the generalized
Hubbard model, subjected to the condition that the number of double occupied
sites is conserved, for a wide, physically relevant range of parameters. For
one hole and one double occupied site the existence of the ferromagnetic
ground-state is proved which allow one to determine the critical value of the
on-site repulsion corresponding to the point of metal-insulator transition. For
the one dimensional model the exact solution for special values of the
parameters is obtained.Comment: 20 pages, LaTex. Mod.Phys.Lett.B 7 (1993) 1397; Journal of Physics:
Condensed Matter (to appear
The smallest Mealy automaton of intermediate growth
In this paper we study the smallest Mealy automaton of intermediate growth,
first considered by the last two authors. We describe the automatic
transformation monoid it defines, give a formula for the generating series for
its (ball volume) growth function, and give sharp asymptotics for its growth
function, namely [ F(n) \sim 2^{5/2} 3^{3/4} \pi^{-2} n^{1/4}
\exp{\pi\sqrt{n/6}} ] with the ratios of left- to right-hand side tending to 1
as
"Infiltrators" or refugees? An analysis of Israel's policy towards African asylum seekers
This article adopts a genealogical approach in examining Israeli immigration policy by focusing on the situation confronting African asylum seekers who have been forced back into Egypt, detained and deported but who have not had their asylum claims properly assessed. Based on immigration policies formulated at the time of Israeli independence, whose principle objective was to secure a Jewish majority state, we argue that Israel’s treatment of African asylum seekers as ‘infiltrators’/economic migrants stems from an insistence on maintaining immigration as a sovereign issue formally isolated from other policy domains. Such an
approach is not only in violation of Israel’s commitment to the Refugee Convention, it directly contributes to policies which are ineffective and unduly harsh
A systematic review protocol examining workplace interventions that aim to improve employee health and wellbeing in male-dominated industries
Are advanced methods necessary to improve infant fNIRS data analysis? An assessment of baseline-corrected averaging, general linear model (GLM) and multivariate pattern analysis (MVPA) based approaches
In the last decade, fNIRS has provided a non-invasive method to investigate
neural activation in developmental populations. Despite its increasing use in
developmental cognitive neuroscience, there is little consistency or consensus
on how to pre-process and analyse infant fNIRS data. With this registered
report, we investigated the feasibility of applying more advanced statistical
analyses to infant fNIRS data and compared the most commonly used
baseline-corrected averaging, General Linear Model (GLM)-based univariate, and
Multivariate Pattern Analysis (MVPA) approaches, to show how the conclusions
one would draw based on these different analysis approaches converge or differ.
The different analysis methods were tested using a face inversion paradigm
where changes in brain activation in response to upright and inverted face
stimuli were measured in thirty 4-to-6-month-old infants. By including more
standard approaches together with recent machine learning techniques, we aim to
inform the fNIRS community on alternative ways to analyse infant fNIRS
datasets
Variable Point Sources in Sloan Digital Sky Survey Stripe 82. I. Project Description and Initial Catalog (0 h < R.A. < 4 h)
We report the first results of a study of variable point sources identified
using multi-color time-series photometry from Sloan Digital Sky Survey (SDSS)
Stripe 82 over a span of nearly 10 years (1998-2007). We construct a
light-curve catalog of 221,842 point sources in the R.A. 0-4 h half of Stripe
82, limited to r = 22.0, that have at least 10 detections in the ugriz bands
and color errors of < 0.2 mag. These objects are then classified by color and
by cross-matching them to existing SDSS catalogs of interesting objects. We use
inhomogeneous ensemble differential photometry techniques to greatly improve
our sensitivity to variability. Robust variable identification methods are used
to extract 6520 variable candidates in this dataset, resulting in an overall
variable fraction of ~2.9% at the level of 0.05 mag variability. A search for
periodic variables results in the identification of 30 eclipsing/ellipsoidal
binary candidates, 55 RR Lyrae, and 16 Delta Scuti variables. We also identify
2704 variable quasars matched to the SDSS Quasar catalog (Schneider et al.
2007), as well as an additional 2403 quasar candidates identified by their
non-stellar colors and variability properties. Finally, a sample of 11,328
point sources that appear to be nonvariable at the limits of our sensitivity is
also discussed. (Abridged.)Comment: 67 pages, 27 figures. Accepted for publication in ApJS. Catalog
available at http://shrike.pha.jhu.edu/stripe82-variable
Revealing the role of the autonomic nervous system in the development and maintenance of Goldblatt hypertension in rats
Despite extensive use of the renovascular/Goldblatt model of hypertension-2K-1C, and the use of renal denervation to treat drug resistant hypertensive patients, autonomic mechanisms that underpin the maintenance of this hypertension are important yet remain unclear. Our aim was to analyse cardiovascular autonomic function by power spectral density analysis of both arterial pressure and pulse interval measured continuously by radio telemetry for 6 weeks after renal artery clipping. Mean arterial pressure increased from 106 +/- 5 to 185 +/- 2 mm Hg during 5 weeks post clipping when it stabilized. A tachycardia developed during the 4th week, which plateaued between weeks 5 and 6. the gain of the cardiac vagal baroreflex decreased immediately after clipping and continued to do so until the 5th week when it plateaued (from -2.4 +/- 0.09 to -0.8 +/- 0.04 bpm/mm Hg; P < 0.05). A similar time course of changes in the high frequency power spectral density of the pulse interval was observed (decrease from 13.4 +/- 0.6 to 8.3 +/- 0.01 ms(2); P < 0.05). There was an increase in both the very low frequency and low frequency components of systolic blood pressure that occurred 3 and 4 weeks after clipping, respectively. Thus, we show for the first time the temporal profile of autonomic mechanisms underpinning the initiation, development and maintenance of renovascular hypertension including: an immediate depression of cardiac baroreflex gain followed by a delayed cardiac sympathetic predominance; elevated sympathetic vasomotor drive occurring after the initiation of the hypertension but coinciding during its mid-development and maintenance. (C) 2014 the Authors. Published by Elsevier B.V.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)British Heart FoundationNIHUniv Bristol, Sch Physiol & Pharmacol, Bristol BS8 1TD, Avon, EnglandUniversidade Federal de São Paulo, UNIFESP, Dept Physiol, BR-04023062 São Paulo, BrazilUniversidade Federal de São Paulo, UNIFESP, Dept Physiol, BR-04023062 São Paulo, BrazilWeb of Scienc
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