Interpulse Interval Distribution in the Environment of N Periodic Radars

We have studied the stochastic behavior of Fitzhugh–Nagumo neuron-like model (FN) induced by subthreshold external stimuli. Our analysis based on three standard measures: the power spectrum, interspike interval distribution (ISI) and autocorrelation function shows that it is possible to define a characteristic time scale which can be identified in the response of the system for a wide range of frequencies. In contrast to previous studies we have focused our attention on high frequency signals which could be of interest for real systems such as nervous fibers in the auditory system. We report behaviors which resemble those of classical deterministic oscillators but never the stochastic resonance phenomenon typical of low frequency signals.

Download Full-text

Sitagliptin decreases visceral fat and blood glucoses in women with polycystic ovarian syndrome

10.1101/19001685 ◽

2019 ◽

Author(s):

Jessica K. Devin ◽

Hui Nian ◽

Jorge E. Celedonio ◽

Patricia Wright ◽

Nancy J. Brown

Keyword(s):

Body Composition ◽

Half Life ◽

Vascular Function ◽

Polycystic Ovarian Syndrome ◽

Interpulse Interval ◽

Oral Glucose ◽

Insulinogenic Index ◽

Glucose Response ◽

Gh Secretion ◽

Ovarian Syndrome

ContextWomen with polycystic ovarian syndrome (PCOS) have decreased growth hormone (GH), which can increase visceral adiposity (VAT) and impair vascular function. GH releasing hormone, a dipeptidyl peptidase-4 (DPP4) substrate, stimulates GH secretion.ObjectiveWe tested the hypothesis that DPP4 inhibition increases GH and improves glucose levels and vascular function in women with PCOS.MethodsEighteen women with PCOS participated in a double-blinded, cross-over study. They received sitagliptin 100 mg vs. placebo daily for one month separated by an eight-week washout. During each treatment, women underwent a 75-gram oral glucose tolerance test (OGTT), assessment of vascular function and body composition. Overnight GH secretion was assessed via venous sampling every 10 minutes for 12 hours and analyzed using an automated deconvolution algorithm.ResultsDuring OGTT, sitagliptin increased GLP-1 (p<0.001), early insulin secretion (from mean insulinogenic index 1.9±1.2 (SD) to 3.2±3.1; p=0.02) and decreased peak glucose (mean −17.2 mg/dL [95% CI −27.7, −6.6]; p<0.01). At one month, sitagliptin decreased VAT (from 1141.9±700.7 to 1055.1±710.1 g; p=0.02) but did not affect vascular function. Sitagliptin increased GH half-life (from 13.9±3.6 to 17.0±6.8 min, N=16; p=0.04) and interpulse interval (from 53.2±20.0 to 77.3±38.2 min, N=16; p<0.05) but did not increase mean overnight GH (p=0.92 vs. placebo).ConclusionsSitagliptin decreased the maximal glucose response to OGTT and VAT. Sitagliptin did not increase overnight GH but increased GH half-life and the interpulse interval.PrecisSitagliptin improved body composition and blood glucoses following oral glucose load in women with PCOS. Sitagliptin potentiated GH half-life but did not increase overnight GH levels.

Download Full-text

Genetic variability of the interpulse interval of courtship song among some European populations of Drosophila melanogaster

Heredity ◽

10.1038/hdy.1994.64 ◽

1994 ◽

Vol 72 (5) ◽

pp. 459-464 ◽

Cited By ~ 32

Author(s):

Michael G Ritchie ◽

Vikki H Yate ◽

Charalambos P Kyriacou

Keyword(s):

Drosophila Melanogaster ◽

Genetic Variability ◽

Courtship Song ◽

Interpulse Interval ◽

European Populations

Download Full-text

Single-channel analysis of a K channel at basolateral membrane of rabbit proximal convoluted tubule

AJP Renal Physiology ◽

10.1152/ajprenal.1988.254.1.f105 ◽

1988 ◽

Vol 254 (1) ◽

pp. F105-F113 ◽

Cited By ~ 4

Author(s):

L. Parent ◽

J. Cardinal ◽

R. Sauve

Keyword(s):

Single Channel ◽

Basolateral Membrane ◽

Proximal Convoluted Tubule ◽

Time Interval ◽

Distribution Analysis ◽

Patch Clamp Technique ◽

Bathing Medium ◽

Patch Pipette ◽

K Concentration ◽

Interval Distribution

The basolateral membrane of the rabbit proximal convoluted tubule (PCT) is known to be largely permeable to K ions. The patch-clamp technique was used to investigate the molecular basis of this K permeability. At room temperature and with a high-K solution (127 mM) in both the bathing medium and the patch pipette, current jumps associated with an inward-rectifying channel could be detected in every active cell-attached experiment. When the K concentration in the pipette was changed from 200 to 5 mM KCl (NaCl replacement), the single-channel conductance for inward currents changed from 54 to 10 pS. The observed shift in the zero current potential measured as a function of the patch pipette K concentration could be fitted using the Goldman-Hodgkin-Katz equation with a permeability ratio PNa/PK = 0.06. The channel was found to be moderately voltage dependent (e-fold per 56 mV depolarization). For instance, the open-channel probability (Po) increased from 0.06 to 0.16 following a membrane depolarization from -50 to +50 mV. A time interval distribution analysis showed for the open state a dominant single time constant of 14 and 10 ms at 50 and -50 mV, respectively. Two time constants equal to 1 (flickering) and 26 ms at +50 mV and to 0.6 and 300 ms at -50 mV were obtained for the closed-state interval distribution. Based on this analysis, it was concluded that the decrease of Po at negative potentials was due more to the appearance of prolonged silent periods than from a change in the channel mean open time.

Download Full-text

Selective interaction between two independent stationary recurrent point processes

Journal of Applied Probability ◽

10.1017/s0021900200035099 ◽

1970 ◽

Vol 7 (02) ◽

pp. 476-482 ◽

Cited By ~ 1

Author(s):

S. K. Srinivasan ◽

G. Rajamannar

Keyword(s):

Point Process ◽

Point Processes ◽

Short Note ◽

Secondary Process ◽

Statistical Features ◽

Inhibitory Process ◽

Primary Event ◽

Recurrent Point ◽

Selective Interaction ◽

Interval Distribution

In an earlier contribution to this Journal, Ten Hoopen and Reuver [5] have studied selective interaction of two independent recurrent processes in connection with the unitary discharges of neuronal spikes. They have assumed that the primary process called excitatory is a stationary renewal point process characterised by the interval distribution ϕ(t). The secondary process called the inhibitory process also consists of a series of events governed by a stationary renewal point process characterised by the interval distribution Ψ(t). Each secondary event annihilates the next primary event. If there are two or more secondary events without a primary event, only one subsequent primary event is deleted. Every undeleted event gives rise to a response. For this reason, undeleted events may be called registered events. Ten Hoopen and Reuver have studied the interval distribution between two successive registered events. As is well-known, the interval distribution does not fully characterise a point process in general and in this case it would be interesting to obtain other statistical features like the moments of the number of undeleted events in a given interval as well as correlations of these events. The object of this short note is to point out that the point process consisting of the undeleted events can be studied directly by the recent techniques of renewal point processes ([1], [3]).

Download Full-text

The basic reproduction number and prediction of the epidemic size of the novel coronavirus (COVID-19) in Shahroud, Iran

Epidemiology and Infection ◽

10.1017/s0950268820001247 ◽

2020 ◽

Vol 148 ◽

Cited By ~ 1

Author(s):

A. Khosravi ◽

R. Chaman ◽

M. Rohani-Rasaf ◽

F. Zare ◽

S. Mehravaran ◽

...

Keyword(s):

Basic Reproduction Number ◽

Reproduction Number ◽

Early Stage ◽

Screening Tests ◽

The Novel ◽

Epidemic Size ◽

Serial Interval ◽

Novel Coronavirus ◽

Interval Distribution ◽

The Basic Reproduction Number

Abstract The aim of this study was to estimate the basic reproduction number (R0) of COVID-19 in the early stage of the epidemic and predict the expected number of new cases in Shahroud in Northeastern Iran. The R0 of COVID-19 was estimated using the serial interval distribution and the number of incidence cases. The 30-day probable incidence and cumulative incidence were predicted using the assumption that daily incidence follows a Poisson distribution determined by daily infectiousness. Data analysis was done using ‘earlyR’ and ‘projections’ packages in R software. The maximum-likelihood value of R0 was 2.7 (95% confidence interval (CI): 2.1−3.4) for the COVID-19 epidemic in the early 14 days and decreased to 1.13 (95% CI 1.03–1.25) by the end of day 42. The expected average number of new cases in Shahroud was 9.0 ± 3.8 cases/day, which means an estimated total of 271 (95% CI: 178–383) new cases for the period between 02 April to 03 May 2020. By day 67 (27 April), the effective reproduction number (Rt), which had a descending trend and was around 1, reduced to 0.70. Based on the Rt for the last 21 days (days 46–67 of the epidemic), the prediction for 27 April to 26 May is a mean daily cases of 2.9 ± 2.0 with 87 (48–136) new cases. In order to maintain R below 1, we strongly recommend enforcing and continuing the current preventive measures, restricting travel and providing screening tests for a larger proportion of the population.

Download Full-text