The efficiency of the adaptive immune system is dependent on the diversity of T- and B-cell receptors, which is created by random rearrangement of receptor gene segments. AmpliCot is an experimental technique that allows the measurement of the diversity of the T- and B-cell repertoire. This procedure has the advantage over other cloning and sequencing techniques of being time- and expense-effective. In previous studies, receptor diversity, measured with AmpliCot, has been inferred assuming a second-order kinetics model. The latter implies that the relation between diversity and concentration × time (Cot) values is linear. We show that a more detailed model, involving heteroduplex and transient-duplex formation, leads to significantly better fits of experimental data and to nonlinear diversity-Cot relations. We propose an alternative fitting procedure, which is straightforward to apply and which gives an improved description of the relationship between Cot values and diversity.
In CDMA mobile networks, callers that are transmitting through a power station may cause interference at other power stations. When many users are already connected in the network, a new call may cause the signal to noise ratio to drop below a tolerance threshold. This phenomenon is called "outage" and it provides an important measure of performance, useful in the design and control of the system. Evaluating this probability analytically has proven unsuccessful and only approximations exist today. Direct simulation of such networks is at present very slow because outage occurs infrequently-it may take hours to simulate directly a realistic model if a reasonable precision is desired. Thus this approach is not useful for design problems where one wishes to evaluate and compare performance of many different network models. In this work we implement a change of measure to estimate the outage probability using Importance Sampling. We present a functional estimator and a stochastic approximation method that are capable of learning the best parameters for the change of measure.Dans les résaux CDMA de téléphones mobiles, les utilisateurs transmettantà travers une station de base peuvent créer de l'interférence aux autres stations. Lorsque plusieurs mobiles sont déja connectés au réseau, un nouvel appel peut faire en sorte que le rapport "signal-bruit" descende sous le seuil de tolérance. Ce phénomène est appelé "outage" (blocage) et c'est un critère de performance utile pour la conception et le contrôle du système.Évaluer cette probabilié de façon analytique s'étant avéré sans succès, il n'existe de nos jours que des approximations. Or, une simulation directe de tels réseaux est présentement très lente, car le blocage est unévénement rare. Parfois, des heures de simulation sont nécessaires afin d'obtenir une précision raisonable.Ainsi, cette approche n'est pas très utile lorsqu'il s'agit de comparer la performance de différents modèles. Dans ce travail, nous développons un changement de mesure nous permettant d'estimer la probabilité de blocage. Nous présentons un estimateur fonctionnel et une méthode d'approximation stochastique par le gradient qui sont capables de trouver les paramètres optimaux du changement de mesure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.