Search results for "sigmoid"
showing 10 items of 80 documents
Dynamical Models of Interrelation in a Class of Artificial Networks
2020
The system of ordinary differential equations that models a type of artificial networks is considered. The system consists of a sigmoidal function that depends on linear combinations of the arguments minus the linear part. The linear combinations of the arguments are described by the regulatory matrix W. For the three-dimensional cases, several types of matrices W are considered and the behavior of solutions of the system is analyzed. The attractive sets are constructed for most cases. The illustrative examples are provided. The list of references consists of 12 items.
Drugs and the Colon
1983
It is not our intention to review drug effects in the colon, which was done extensively and profoundly by Forth and Rummel1 and Powell.2 Our contribution will present studies of drug effects on physiological absorption and secretion processes obtained in the intact human colon and based on results of intestinal perfusion studies of the whole colon and measurements of transepithelial electrical potential difference (PD) in the rectosigmoid colon. These are at present the practiced and—regarding perfusion studies—most accurate techniques in the hands of clinicians to directly study drug effects on a local dose-response scale in the intact human colon. Since these methods are relatively new an…
Cancer-Related Venous Thrombosis: Residual Vein Thrombosis Improves Screening for Occult Cancer.
2007
Abstract Background. Clinical advantages of extensive screening for occult cancer in patients with idiopathic Deep Vein Thrombosis (DVT) is still debated since this approach improves early detection of cancer but not cancer-related mortality. Recently, we have demonstrated that patients with Residual Vein Thrombosis (RVT), 3 months after DVT, have a high risk for cancer in the subsequent 2 years (Siragusa S et al. Blood2005;106(11):OC262). At the present it is unknown whether RVT assessment may be used to select patients, with idiopathic DVT, who require screening for occult cancer. Objective of the study. We conducted a prospective study evaluating whether a RVT-based screening for cancer …
Using the Hermite Regression Formula to Design a Neural Architecture with Automatic Learning of the “Hidden” Activation Functions
2000
The value of the output function gradient of a neural network, calculated in the training points, plays an essential role for its generalization capability. In this paper a feed forward neural architecture (αNet) that can learn the activation function of its hidden units during the training phase is presented. The automatic learning is obtained through the joint use of the Hermite regression formula and the CGD optimization algorithm with the Powell restart conditions. This technique leads to a smooth output function of αNet in the nearby of the training points, achieving an improvement of the generalization capability and the flexibility of the neural architecture. Experimental results, ob…
Pneumatosis cystoides intestinalis
1977
Bei der Pneumatosis cystoides intestinalis handelt es sich um Gascysten von Stecknadelkopf- bis Kirschgrose, die sich in der Wand des Dunndarms, des Coecums und im linksseitigen Dickdarm finden. Aber auch ein Befall des gesamten Colons ist beschrieben worden. Die Erkrankung kann in jeder Altersstufe auftreten. Histologisch lassen sich bei Serienschnitten kommunizierende Systeme von Gascysten nachweisen, die bei Jugendlichen submucos und im hoheren Alter subseros liegen. Die Zusammensetzung des Gases entspricht der der Atemluft.
Technik der Mesohepatektomie
2016
Bei Patienten mit einer primar oder sekundar malignen zentralen Leberraumforderung stellt die Resektion im Sinne einer erweiterten Hemihepatektomie rechts bzw. links das Standardverfahren dar. Unter Berucksichtigung der erhohten Morbiditat und Mortalitat bei erweiterten Resektionen und dem Aspekt des hohen Verlusts an gesundem Lebergewebe stellt die zentrale Leberresektion oder Mesohepatektomie (Resektion der Segmente 4a/4b, 5 und 8) mit oder ohne Resektion des Segments 1 eine technisch anspruchsvolle und weiterhin selten genutzte Alternative dar. Die Resektionsgrenzen liegen rechtsseitig des Lig. falciforme und auf der oft schwierig zu identifizierenden Grenze zwischen den Segmenten 5/6 so…
Spatially localized solutions of the Hammerstein equation with sigmoid type of nonlinearity
2016
Abstract We study the existence of fixed points to a parameterized Hammerstein operator H β , β ∈ ( 0 , ∞ ] , with sigmoid type of nonlinearity. The parameter β ∞ indicates the steepness of the slope of a nonlinear smooth sigmoid function and the limit case β = ∞ corresponds to a discontinuous unit step function. We prove that spatially localized solutions to the fixed point problem for large β exist and can be approximated by the fixed points of H ∞ . These results are of a high importance in biological applications where one often approximates the smooth sigmoid by discontinuous unit step function. Moreover, in order to achieve even better approximation than a solution of the limit proble…
The occlusive tourniquet: a simple method for rectal stump washout during open and laparoscopic surgery.
2007
Rectal stump washout with cytolytic agents is recommended and usually performed during anterior rectal or rectosigmoid resection. The use of a linear stapler instrument during ultralow anterior resection makes the placement of pelvic clamps difficult for rectal stump washout prior to resection. The objective of this work is to demonstrate the use of a simple procedure, the occlusive tourniquet for rectal stump washout. Occlusive tourniquet applied to open technique: after complete dissection of the rectum and sigmoid colon according to the usual technique, a simple piece of tubing from an intravenous line is passed behind and around the rectum/sigmoid colon at some point distal to the tumor…
The problem of spatial homogeneity in an LCoS projector
2019
Abstract Video projectors allow interesting applications in vision sciences since they provide a large projection area. We have colorimetrically characterized a LCoS projector using a mathematical model requiring additivity and constancy of the primaries -a sigmoid function in our case. Significant differences in chromaticity in the CIELAB space, but not in lightness, were found between the center and the corners of the screen. The lack of spatial homogeneity led us to estimate the parameters of the model as a function of spatial position, using different strategies. The best result was obtained by interpolating the values of the parameters of the model determined from experimental measurem…
Trends in colorectal cancer incidence: a period and birth-cohort analysis in a well-defined French population.
2011
Abstract Background France stands among high-risk areas for colorectal cancer. Different trends in CRC incidence are reported around the world. The aim of this study was to provide temporal trends in CRC incidence over a 30-year period in a French well-defined population. Methods Between 1976 and 2005, 17,028 new cases were registered by the Burgundy digestive cancer registry. The mean variations in age-standardized incidence rates were estimated using a Poisson regression adjusted for age for each gender and location. The cumulative risk by birth cohort of developing a cancer over the age range 0-74 years was estimated using an age-cohort model. Results Incidence rates for right and left c…