884 resultados para Concept inventories


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The aim of this brief is to present an original design methodology that permits implementing latch-up-free smart power circuits on a very simple, cost-effective technology. The basic concept used for this purpose is letting float the wells of the MOS transistors most susceptible to initiate latch-up.

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The paper addresses the concept of multicointegration in panel data frame- work. The proposal builds upon the panel data cointegration procedures developed in Pedroni (2004), for which we compute the moments of the parametric statistics. When individuals are either cross-section independent or cross-section dependence can be re- moved by cross-section demeaning, our approach can be applied to the wider framework of mixed I(2) and I(1) stochastic processes analysis. The paper also deals with the issue of cross-section dependence using approximate common factor models. Finite sample performance is investigated through Monte Carlo simulations. Finally, we illustrate the use of the procedure investigating inventories, sales and production relationship for a panel of US industries.

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Colleagues, Ladies and Gentlemen. My presence here is due to accidental circumstances and I must confess that I feel a little embarassed by the fact Both your scientific quality and the worlwide acceptance of the results achieved by you in your research fields make me prudent and, to a certain extent, cautious.

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Abstract Empirical testing of candidate vaccines has led to the successful development of a number of lifesaving vaccines. The advent of new tools to manipulate antigens and new methods and vectors for vaccine delivery has led to a veritable explosion of potential vaccine designs. As a result, selection of candidate vaccines suitable for large-scale efficacy testing has become more challenging. This is especially true for diseases such as dengue, HIV, and tuberculosis where there is no validated animal model or correlate of immune protection. Establishing guidelines for the selection of vaccine candidates for advanced testing has become a necessity. A number of factors could be considered in making these decisions, including, for example, safety in animal and human studies, immune profile, protection in animal studies, production processes with product quality and stability, availability of resources, and estimated cost of goods. The "immune space template" proposed here provides a standardized approach by which the quality, level, and durability of immune responses elicited in early human trials by a candidate vaccine can be described. The immune response profile will demonstrate if and how the candidate is unique relative to other candidates, especially those that have preceded it into efficacy testing and, thus, what new information concerning potential immune correlates could be learned from an efficacy trial. A thorough characterization of immune responses should also provide insight into a developer's rationale for the vaccine's proposed mechanism of action. HIV vaccine researchers plan to include this general approach in up-selecting candidates for the next large efficacy trial. This "immune space" approach may also be applicable to other vaccine development endeavors where correlates of vaccine-induced immune protection remain unknown.

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We study the interaction between two independent nonlinear oscillators competing through a neutral excitable element. The first oscillator, completely deterministic, acts as a normal pacemaker sending pulses to the neutral element which fires when it is excited by these pulses. The second oscillator, endowed with some randomness, though unable to make the excitable element to beat, leads to the occasional suppression of its firing. The missing beats or errors are registered and their statistics analyzed in terms of the noise intensity and the periods of both oscillators. This study is inspired in some complex rhythms such as a particular class of heart arrhythmia.

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This report documents Phase IV of the Highway Maintenance Concept Vehicle (HMCV) project, a pooled fund study sponsored by the Departments of Transportation of Iowa, Pennsylvania, and Wisconsin. This report provides the background, including a brief history of the earlier phases of the project, a systems overview, and descriptions of the research conducted in Phase IV. Finally, the report provides conclusions and recommendations for future research. Background The goal of the Highway Maintenance Concept Vehicle Pooled Fund Study is to provide travelers with the level of service defined by policy during the winter season at the least cost to taxpayers. This goal is to be accomplished by using information regarding actual road conditions to facilitate and adjust snow and ice control activities. The approach used in this study was to bring technology applications from other industries to the highway maintenance vehicle. This approach is evolutionary in that as emerging technologies and applications are found to be acceptable to the pooled fund states and as they appear that to have potential for supporting the study goals they become candidates for our research. The objective of Phase IV is to: Conduct limited deployment of selected technologies from Phase III by equipping a vehicle with proven advanced technologies and creating a mobile test laboratory for collecting road weather data. The research quickly pointed out that investments in winter storm maintenance assets must be based on benefit/cost analysis and related to improving level of service. For example, Iowa has estimated the average cost of fighting a winter storm to be about $60,000 to $70,000 per hour typically. The maintenance concept vehicle will have advanced technology equipment capable of applying precisely the correct amount of material, accurately tailored to the existing and predicted pavement conditions. Hence, a state using advanced technology could expect to have a noticeable impact on the average time taken to establish the winter driving service level. If the concept vehicle and data produced by the vehicle are used to support decision-making leading to reducing material usage and the average time by one hour, a reasonable benefit/cost will result. Data from the friction meter can be used to monitor and adjust snow and ice control activities and inform travelers of pavement surface conditions. Therefore, final selection of successfully performing technologies will be based on the foundation statements and criteria developed by the study team.

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The rationale of this study was to investigate molecular flexibility and its influence on physicochemical properties with a view to uncovering additional information on the fuzzy concept of dynamic molecular structure. Indeed, it is now known that computed molecular interaction fields (MIFs) such as molecular electrostatic potentials (MEPs) and lipophilicity potentials (MLPs) are conformation-dependent, as are dipole moments. A database of 125 compounds was used whose conformational space was explored, while conformation-dependent parameters were computed for each non-redundant conformer found in the conformational space of the compounds. These parameters were the virtual log P (log P(MLP), calculated by a MLP approach), the apolar surface area (ASA), polar surface area (PSA), and solvent-accessible surface (SAS). For each compound, the range taken by each parameter (its property space) was divided by the number of rotors taken as an index of flexibility, yielding a parameter termed 'molecular sensitivity'. This parameter was poorly correlated with others (i.e., it contains novel information) and showed the compounds to fall into two broad classes. 'Sensitive' molecules are those whose computed property ranges are markedly sensitive to conformational effects, whereas 'insensitive' (in fact, less sensitive) molecules have property ranges which are comparatively less affected by conformational fluctuations. A pharmacokinetic application is presented.

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Popularisée par l'usage extensif (et de ce fait quelque peu galvaudé) qu'en fit Gérard Genette en narratologie littéraire, la « diégèse » constitue certes la notion vedette des filmologues, mais elle fut pendant plusieurs décennies le lieu d'une certaine occultation de son champ originel en raison des appropriations non référencées qu'en firent poéticiens et sémiologues. En suivant le fil historiographique des différents emplois et acceptions de cette notion associée à Etienne Souriau dans l'espace francophone, le présent article propose un état des lieux qui, par la petite porte d'une entrée terminologique, entend s'interroger sur les conséquences théoriques des variations que le terme « diégèse » a subies et, plus généralement, sur la question du statut octroyé au courant filmologique. En examinant les différentes implications de la définition première qu'il s'agit parfois de délester de sens dont on l'a ultérieurement investie, cet article tente de montrer que le cadre dans lequel la diégèse a été conceptualisée contient des potentialités théoriques qui n'ont pas encore été épuisées aujourd'hui, et qui convergent avec certains champs d'étude récents (comme celui de la logique des mondes possibles) dont l'application au cinéma n'a probablement jamais été aussi pertinent qu'à l'ère des images de synthèse, des mondes virtuels et des environnements de jeux vidéo.

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The function of DNA-binding proteins is controlled not just by their abundance, but mainly at the level of their activity in terms of their interactions with DNA and protein targets. Moreover, the affinity of such transcription factors to their target sequences is often controlled by co-factors and/or modifications that are not easily assessed from biological samples. Here, we describe a scalable method for monitoring protein-DNA interactions on a microarray surface. This approach was designed to determine the DNA-binding activity of proteins in crude cell extracts, complementing conventional expression profiling arrays. Enzymatic labeling of DNA enables direct normalization of the protein binding to the microarray, allowing the estimation of relative binding affinities. Using DNA sequences covering a range of affinities, we show that the new microarray-based method yields binding strength estimates similar to low-throughput gel mobility-shift assays. The microarray is also of high sensitivity, as it allows the detection of a rare DNA-binding protein from breast cancer cells, the human tumor suppressor AP-2. This approach thus mediates precise and robust assessment of the activity of DNA-binding proteins and takes present DNA-binding assays to a high throughput level.