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Results for “Environment, Controlled”

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At least 307 records · Page 17Linked to original sources
PubMed1997

Using the radial distributions of physical features to compare amino acid environments and align amino acid sequences.

We have performed a comprehensive analysis of the microenvironments surrounding the twenty amino acids. Our analysis includes comparison of amino acid environments with random control environments as well as with each of the other amino acid environments. We describe the amino acid environments with a set of 21 features summarizing atomic, chemical group, residue, and secondary structural features. The environments are divided into radial shells of 1 A thickness to represent the distance of the features from the amino acid C beta atoms. We make the results of our analysis available graphically over the world wide web. To illustrate the validity and utility of our analysis, we used the amino acid comparative profiles to construct a substitution matrix, the WAC matrix, based on a simple summary of the computed environmental differences. We compared our matrix to BLOSUM62 and PAM250 in BLAST searches with query sequences selected from 39 protein families found in the PROSITE database. Although BLOSUM62 was the most sensitive matrix overall, our matrix was more sensitive for some families, and exhibited overall performance similar to PAM250. Our results suggest that the radial distribution of biochemical and biophysical features is useful for comparing amino acid environments, and that similarity matrices based on the geometric distribution of features around amino acids may produce improved search sensitivity.

Amino Acid Sequence↗
PubMed2003

[Environmental control and life support system of spacecraft].

Environment control and life support system is a very complicated and important subsystem of manned spacecraft. It is a key technology must be broken through for the realization of manned space flight. Its functions, technical requirements and main technology were reviewed in this paper. Its test verification was also discussed.

Ecological Systems, Closed↗
PubMed1995

[Control of the work environment in Sweden. I. Instances of control].

The authors discuss the system of the working environment control in Sweden. They presented the organizational structure, objectives, range of activities and priorities of the Labour Inspectorate--a state administration organ responsible for a direct supervision of individual establishments. Basic figures on the control and supervising activities of the Inspection for 1994 are given. The system how the National Board of Occupational Safety, Hygiene and Workers' Health--a body superior to the Labour Inspectorate--coordinates and monitors its activities, is also presented.

Environmental Monitoring↗
PubMedDate not supplied

Digitized infrared segmental thermometry: time requirements for stable recordings.

OBJECTIVES: Digitized infrared segmental thermometry (DIST) is a method for measuring and recording skin surface body temperatures. The project evaluated the required length of time for patients to acclimatize their core body temperature to ambient conditions to obtain stable DIST readings. METHODS: Seventeen subjects were allowed a 20-minute acclimatizing period in a temperature-controlled room. The bilateral DIST temperature was measured with thermistors in combination with infrared cameras (IRCs) at the C4 and L4 levels. All IRC temperatures were recorded after a 20-minute stabilization period. The room temperature and relative humidity were recorded throughout all trials. The acclimatization trend was computed from the 20- to 24-minute period for the IRCs, and the acclimatization trend was computed continuously for a total of 30 minutes (at 2-minute intervals) for 5 days. RESULTS: We discovered a stabilization trend in the early trial stages, with the thermistor recordings between 8 and 16 minutes. The IRC trend was also conclusive for the core temperature requirements. CONCLUSIONS: This study determined a core body temperature acclimatization trend tested among patients using thermistor recordings in a controlled environment. Based on these findings, we recommend acclimatization in a temperature- and humidity-controlled environment for a minimum 8-minute period, followed by an 8-minute maximum recording period with the patient in a prone position to obtain accurate DIST recordings.

Acclimatization↗
PubMed1984

The impact of radionuclides in the environment: assessment, control and perspective.

The objective of this brief paper is to highlight the way in which we assess and control the impact of environmentally dispersed radionuclides. It touches on the assessment of dispersion of radionuclides in the environment, their transfer to man, the resultant dose to man and the presumed health consequences, the control of releases based on such assessments and some perspective against which to judge the results of control policies.

Humans↗
PubMed2006

Environment-mediated control of a quantum system.

Recently, a new approach for the controllability of a two-dimensional quantum system S has been proposed, based on its interaction with an initially uncorrelated two-dimensional probe P whose initial state can be arbitrarily modified. Following this scheme and considering a particular model for the environment, we show that, in some specific cases, the environment-induced entanglement is rich enough to completely control the dynamics of S. Under suitable conditions on the interaction of S, P, and the environment, we prove that the state of S can be driven to an arbitrary target state by varying the initial state of P.

Journal Article↗
PubMed2005

Features and uses of high-fidelity medical simulations that lead to effective learning: a BEME systematic review.

REVIEW DATE: 1969 to 2003, 34 years. BACKGROUND AND CONTEXT: Simulations are now in widespread use in medical education and medical personnel evaluation. Outcomes research on the use and effectiveness of simulation technology in medical education is scattered, inconsistent and varies widely in methodological rigor and substantive focus. OBJECTIVES: Review and synthesize existing evidence in educational science that addresses the question, 'What are the features and uses of high-fidelity medical simulations that lead to most effective learning?'. SEARCH STRATEGY: The search covered five literature databases (ERIC, MEDLINE, PsycINFO, Web of Science and Timelit) and employed 91 single search terms and concepts and their Boolean combinations. Hand searching, Internet searches and attention to the 'grey literature' were also used. The aim was to perform the most thorough literature search possible of peer-reviewed publications and reports in the unpublished literature that have been judged for academic quality. INCLUSION AND EXCLUSION CRITERIA: Four screening criteria were used to reduce the initial pool of 670 journal articles to a focused set of 109 studies: (a) elimination of review articles in favor of empirical studies; (b) use of a simulator as an educational assessment or intervention with learner outcomes measured quantitatively; (c) comparative research, either experimental or quasi-experimental; and (d) research that involves simulation as an educational intervention. DATA EXTRACTION: Data were extracted systematically from the 109 eligible journal articles by independent coders. Each coder used a standardized data extraction protocol. DATA SYNTHESIS: Qualitative data synthesis and tabular presentation of research methods and outcomes were used. Heterogeneity of research designs, educational interventions, outcome measures and timeframe precluded data synthesis using meta-analysis. HEADLINE RESULTS: Coding accuracy for features of the journal articles is high. The extant quality of the published research is generally weak. The weight of the best available evidence suggests that high-fidelity medical simulations facilitate learning under the right conditions. These include the following: providing feedback--51 (47%) journal articles reported that educational feedback is the most important feature of simulation-based medical education; repetitive practice--43 (39%) journal articles identified repetitive practice as a key feature involving the use of high-fidelity simulations in medical education; curriculum integration--27 (25%) journal articles cited integration of simulation-based exercises into the standard medical school or postgraduate educational curriculum as an essential feature of their effective use; range of difficulty level--15 (14%) journal articles address the importance of the range of task difficulty level as an important variable in simulation-based medical education; multiple learning strategies--11 (10%) journal articles identified the adaptability of high-fidelity simulations to multiple learning strategies as an important factor in their educational effectiveness; capture clinical variation--11 (10%) journal articles cited simulators that capture a wide variety of clinical conditions as more useful than those with a narrow range; controlled environment--10 (9%) journal articles emphasized the importance of using high-fidelity simulations in a controlled environment where learners can make, detect and correct errors without adverse consequences; individualized learning--10 (9%) journal articles highlighted the importance of having reproducible, standardized educational experiences where learners are active participants, not passive bystanders; defined outcomes--seven (6%) journal articles cited the importance of having clearly stated goals with tangible outcome measures that will more likely lead to learners mastering skills; simulator validity--four (3%) journal articles provided evidence for the direct correlation of simulation validity with effective learning. CONCLUSIONS: While research in this field needs improvement in terms of rigor and quality, high-fidelity medical simulations are educationally effective and simulation-based education complements medical education in patient care settings.

Clinical Competence↗
PubMed1996

A comparison of morphine, pethidine and fentanyl in the postsurgical patient-controlled analgesia environment.

This study was designed to evaluate whether there is any scientific basis for clinicians' preferences for selecting opioids for use in patient-controlled analgesia (PCA) and to determine whether there are any patients' preferences for being treated with any of these opioids. Results were obtained for 55 postoperative patients recruited to investigate putatively equivalent doses of 3 commonly used opioids--morphine, pethidine and fentanyl--when self-administered postoperatively. No significant differences in the incidence of side effects between groups were found with the exception of more pruritus reported in the group given morphine. Patients who experienced vomiting or pruritus reported a greater intensity of these side effects if receiving morphine and fentanyl than if receiving pethidine. The majority of patients reported being very satisfied with their postoperative pain management and with PCA, with no differences in satisfaction between the 3 opioid-treated groups. A senior consultant anaesthetist, when asked to make a judgement, was not able to identify which agent each patient was receiving with a better than chance accuracy. These findings suggest that while there may be subtle differences in patient response to these 3 commonly used opioids, none was obviously superior when used for postoperative PCA.

Adult↗
PubMed1998

Generating controlled reducing environments in aerobic recombinant Escherichia coli fermentations: effects on cell growth, oxygen uptake, heat shock protein expression, and in vivo CAT activity.

The independent control of culture redox potential (CRP) by the regulated addition of a reducing agent, dithiothreitol (DTT) was demonstrated in aerated recombinant Escherichia coli fermentations. Moderate levels of DTT addition resulted in minimal changes to specific oxygen uptake, growth rate, and dissolved oxygen. Excessive levels of DTT addition were toxic to the cells resulting in cessation of growth. Chloramphenicol acetyltransferase (CAT) activity (nmoles/microgram total protein min.) decreased in batch fermentation experiments with respect to increasing levels of DTT addition. To further investigate the mechanisms affecting CAT activity, experiments were performed to assay heat shock protein expression and specific CAT activity (nmoles/microgram CAT min.). Expression of such molecular chaperones as GroEL and DnaK were found to increase after addition of DTT. Additionally, sigma factor 32 (sigma32) and several proteases were seen to increase dramatically during addition of DTT. Specific CAT activity (nmoles/microgram CAT min. ) varied greatly as DTT was added, however, a minimum in activity was found at the highest level of DTT addition in E. coli strains RR1 [pBR329] and JM105 [pROEX-CAT]. In conjunction, cellular stress was found to reach a maximum at the same levels of DTT. Although DTT addition has the potential for directly affecting intracellular protein folding, the effects felt from the increased stress within the cell are likely the dominant effector. That the effects of DTT were measured within the cytoplasm of the cell suggests that the periplasmic redox potential was also altered. The changes in specific CAT activity, molecular chaperones, and other heat shock proteins, in the presence of minimal growth rate and oxygen uptake alterations, suggest that the ex vivo control of redox potential provides a new process for affecting the yield and conformation of heterologous proteins in aerated E. coli fermentations.

Aerobiosis↗
PubMed1983

Operating characteristics of the vaginal photoplethysmograph: some implications for its use.

Two operating characteristics of the vaginal photoplethysmograph were examined in an attempt to explain some of the methodological variance in the data produced by this device. Both the original Sintchak and Geer (1975) vaginal probe and a modified LED probe were examined for response consistency and temperature sensitivity. The results reveal that, for both types of probes, there is a considerable drift over time when the device is operated on DC in a temperature and light-controlled environment. This drift was not consistent across devices or trials, thus eliminating the possibility of experimentally or statistically controlling for it. In addition, both types of device were found to be extremely temperature sensitive when operated on DC in a light-controlled environment. Implications for continued use of the vaginal photoplethysmograph in research and clinical settings are discussed and recommendations are made regarding alternative genital measures of sexual arousal in women.

Female↗
PubMed2000

In vitro cell shearing device to investigate the dynamic response of cells in a controlled hydrodynamic environment.

Mechanical stresses and strains play important roles in the normal growth and development of biological tissues, yet the cellular mechanisms of mechanotransduction have not been identified. A variety of in vitro systems for applying mechanical loads to cell populations have been developed to gain insight into these mechanisms. However, limitations in the ability to control precisely relevant aspects of the mechanical stimuli have obscured the physical relationships between mechanical loading and the biochemical signals that mediate the cellular response. We present a novel in vitro cell shearing device based on the principles of a cone and plate viscometer that utilizes microstepper motor technology to control independently the dynamic and steady components of a hydrodynamic shear-stress environment. Physical measurements of the cone velocity demonstrated faithful reproduction of user-defined input wave forms. Computational modeling of the fluid environment for the unsteady startup confirmed small inertial contributions and negligible secondary flows. Finally, we present experimental results demonstrating the onset rate dependence of functional and structural responses of endothelial cell cultures to dynamically applied shear stress. The controlled cell shearing device is a novel tool for elucidating mechanisms by which mechanical forces give rise to the biological signals that modulate cellular morphology and metabolism.

Animals↗
PubMed2006

Relationship between blood lead level and work related factors using the NIIH questionnaire system.

Over an 11-yr period (1990-2000), a questionnaire survey on work environmental management and environmental improvement was conducted on 259 lead-handling factories and 7,623 subjects. Labour Inspection Offices identified these factories as requiring environmental improvement, or possessing a desire to improve their working environment. We analyzed factors affecting blood lead levels (PbBs). These factors were gender, age, employment duration, factory size, work environment control (WEC) class, and job categories. The PbB of men was found to be higher than that of women, and may be due to the differences in job distribution. PbB increased along with increasing age and employment duration. PbB declined as the factory size increased. The odds ratio (OR) of PbB higher than 20 microg/dl according to factory size was significantly high even after adjusting for WEC class. This demonstrates that not only the working environment but also safety management was poorer among small-scale factories that large-scale factories. The rise of PbB along with the increase of WEC class confirmed that the results of work environment measurement are correlated with individual exposure levels. The risk of having a 20 microg/dl or higher PbB was different for various lead handling jobs. Smelting or refining lead had the highest risk for lead exposure while painting or baking had the lowest risk. As our study population was not a randomly selected sample, we are unable to generalize our results for workers across Japan. However, we were able to indicate which jobs pose a high-risk and the effectiveness of using the work environment control class as an index of worksite environment levels.

Adult↗