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Appropriate Sample (appropriate + sample)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Is there a SSRI dose response in treating major depression?

DEPRESSION AND ANXIETY, Issue 1 2003
The case for re-analysis of current data, for enhancing future study design
Abstract It has been widely stated that the available research data has not demonstrated a SSRI dose response for major depression. We re-evaluated the methods used to analyze the SSRI data by clarifying two key alternative definitions of dose response and their implications for enhancing analysis of currently available data as well as future study design. We differentiated "potential" dose response, which focuses exclusively on response excluding tolerability effects and asks whether differences in dose can result in significant differences in response, from "expressed" dose response, which incorporates all tolerability effects currently associated with dose (including those caused by study protocol or treatment practice) and asks whether differences in dose do result in significant differences in response. To analyze potential dose response for all studies, one should use a "dose-tolerant" sample, i.e., an ITT sample from which dropouts due to adverse events have been removed. To analyze an expressed dose response, an ITT sample is the optimum sample if the study conforms to several design specifications. In the absence of conformance to these specifications, an ITT sample may be an approximation of the appropriate sample. Given design limitations of currently available studies, a dose-tolerant sample may provide a more informative approximation of an optimal sample to be used in evaluating the expressed dose response that could be expected in the best clinical practice. Future studies of dose-response relations could be enhanced by taking into account the principles noted above, and currently available data should be reanalyzed based on these principles. This re-analysis is performed in a companion article [Baker et al. 2003, Depress Anxiety 17:1-9]. Depression and Anxiety 17:10,18, 2003. © 2003 Wiley-Liss, Inc. [source]

Guaranteed Cost Sampled-Data Control for Refining Process

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1-2 2001
Yingquan Lu
This paper presents a synthetic design procedure of guaranteed cost sampled-data control (GCSDC) for refining process. When a digital controller controls the refining process with appropriate sample and hold devices, the closed loop system is periodic time varying. Based on this sampled-data system, considering the uncertainties in the continuous-time plant, we define the guaranteed cost control and a controller that not only stabilizes the closed loop system but also guarantees an adequate level of the performance. Simulation results show that the control scheme is effective and practicable. [source]

Hemostatic Changes in Dogs with Naturally Occurring Sepsis

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 5 2003
Armelle M. de Laforcade
Sepsis is a frequent source of morbidity and mortality in critically ill patients. The goal of this case control study was to measure hemostatic changes in dogs with naturally occurring sepsis. Blood was collected within 24 hours of admission from 20 dogs that fulfilled the criteria for sepsis. Sepsis was defined as histologic or microbiological confirmation of infection and 2 or more of the following criteria: hypo- or hyperthermia, tachycardia, tachypnea, or leukopenia, leukocytosis, or >3% bands. Culture and sensitivities were performed on appropriate samples from all septic dogs. Twenty-eight control dogs were enrolled on the basis of normal results of physical examination, CBC, serum biochemistry, and coagulation profile. Plasma samples were analyzed for prothrombin time (PT), partial thromboplastin time (PTT), fibrin(ogen) degradation products (FDP), D-dimer (DD) concentrations, antithrombin (AT) activity, and protein C (PC) activity. Data were compared between groups by chi-square or independent t -tests. PC (P < .001) and AT (P < .001) activities were significantly lower in dogs with sepsis compared to controls. Dogs with sepsis had significantly higher PT (P= .007), PTT (P= .005), D-dimer (P= .005), and FDP (P= .001) compared to controls. Platelet counts were not significantly different between groups. Ten of the 20 septic dogs (50%) died, but no association was identified between any of the measured variables and outcome. These findings are consistent with previous studies in animals with experimentally induced disease and in clinical studies of humans. On the basis of these results, further investigation of the role of AT and PC in canine sepsis is warranted. [source]

Besonderheiten bei Alkali-Kieselsäure-Reaktionen in Betonfahrbahndecken

BETON- UND STAHLBETONBAU, Issue 8 2007
Rolf Breitenbücher Prof. Dr.-Ing.
In den letzten Jahren sind Rissbildungen in Betonfahrbahndecken mehrfach mit einer Alkali-Kieselsäure-Reaktion (AKR) in Verbindung gebracht worden. Die Risse sind nur in den seltensten Fällen einzig auf eine AKR zurückzuführen. Vielmehr ist davon auszugehen, dass sie durch Überlagerung mehrerer Spannungsquellen hervorgerufen wurden. Dennoch sind Alkali-Kieselsäure-Reaktionen bei Betonfahrbahndecken nicht zu vernachlässigen. Als Besonderheit kommt hier einer externen Alkalizufuhr eine wesentliche Bedeutung zu. Die in den Wintermonaten aufgestreuten alkalihaltigen Taumittel werden durch den nachfolgenden Verkehr mehr oder weniger intensiv in den Beton eingewalkt. Dabei kann das Eindringen der Alkalien durch Vorschädigungen (Risse) nachhaltig begünstigt werden. Unter diesen Randbedingungen sind bei Betonfahrbahndecken zur Vermeidung von schädigenden Alkali-Kieselsäure-Reaktionen weiterreichendere Maßnahmen als bei herkömmlichen Betonbauteilen notwendig. Solche wurden zwischenzeitlich vom BMVBS mit einem einschlägigen Rundschreiben erlassen. Die darin enthaltenen Vorgaben beziehen sich insbesondere auf die Bewertung von kritischen Gesteinskörnungen und auf den zulässigen Alkaligehalt der Zemente. Die Regelungen dieses Erlasses beruhen zunächst auf allgemeinen empirisch gewonnenen Erkenntnissen. Der tatsächliche Einfluss der Alkali-Kieselsäure-Reaktion auf die Rissbildung in Betonfahrbahndecken wird derzeit in Forschungsprojekten untersucht. Characteristics of Alkali Silica Reactions in Concrete Pavements In the last few years cracking in concrete pavements was often associated with an alkali silica reaction (ASR). Even if relevant reaction products were detected in appropriate samples, cracks result only in the rarest cases from an ASR solely. Rather it is assumed, that cracks were caused by a superposition of several stress impacts. Beside restraint stresses due to disabled thermal and hygric self-deformations, concrete pavements are also stressed by traffic. However, the influence of the alkali silica reaction in concrete pavements can not be neglected. Here especially the infiltration of alkalis from external resources is of a substantial importance. Alkaline deicing agents applied in the winter months are more or less intensively penetrating into the concrete by the following traffic, which leads to a continuous increase of the alkali potential in the concrete. The penetration of the alkalis is forwarded by already existent damages (cracks). Within these circumstances more extensive measures are necessary to avoid damaging alkali silica reactions for concrete pavements in comparison to conventional concrete constructions. In the meantime such measures were decreed by the BMVBS in a relevant circular. The contained requirements refer in particular to the evaluation of critical aggregates and to the permitted alkali content of the cements. The regulations of this decree are initially based on general empirically revealed findings. The actual influence of the alkali silica reaction referring to cracking in concrete pavements is examined in current research projects. [source]