2,238 research outputs found
It Seemed Like Such a Good Idea: Making Sense of How Two Schools, a Major Philanthropy, and a Prestigious Teacher Training Program Agreed on a School Reform Strategy that Was Bound to Fail.
This Capstone project is a reflection on the process through which a major Jewish Philanthropy, two Jewish Day Schools, and a major Teacher Training Program worked together to craft an agenda for school reform and technological progress. That four-month process is carefully narrated in a portion of this document, as is a postscript that explains subsequent events and outcomes. The analytical portion of this document follows, in which concepts drawn from Actor-Network Theory and sensemaking theory are used to make sense of how each institution contributed to the creation of inherently unworkable and impractical plans for school reform
Psychologists Collaborating With Clergy
If a patient adheres to religious values and practices, should the treating psychologist get input from a clergyperson? How frequent is clergy-psychologist collaboration? What obstacles impede such collaboration? An exploratory survey questionnaire was sent to 200 clergy, 200 psychologists interested in religious issues, and 200 psychologists selected without regard to religious interests or values. Four themes were assessed: types of collaborative activities, frequency of collaboration, obstacles to collaboration, and ways to enhance collaboration. Strategies for promoting clergy-psychologist collaboration include challenging unidirectional referral assumptions, building trust through proximity and familiarity, and considering the importance of shared values and beliefs
Cortical and spinal mechanisms of task failure of sustained submaximal fatiguing contractions
In this and the subsequent companion paper, results are presented that collectively seek to delineate the contribution that supraspinal circuits have in determining the time to task failure (TTF) of sustained submaximal contractions. The purpose of this study was to compare adjustments in supraspinal and spinal excitability taken concurrently throughout the performance of two different fatigue tasks with identical mechanical demands but different TTF (i.e., force-matching and position-matching tasks). On separate visits, ten healthy volunteers performed the force-matching or position-matching task at 15% of maximum strength with the elbow flexors to task failure. Single-pulse transcranial magnetic stimulation (TMS), paired-pulse TMS, paired cortico-cervicomedullary stimulation, and brachial plexus electrical stimulation were delivered in a 6-stimuli sequence at baseline and every 2–3 minutes throughout fatigue-task performance. Contrary to expectations, the force-matching task TTF was 42% shorter (17.5±7.9 min) than the position-matching task (26.9±15.11 min; p0.05). Therefore, failure occurred after a similar mean decline in motorneuron excitability developed (p0.10) and an index of upstream excitation of the motor cortex remained constant (p>0.40). Together, these results suggest that as fatigue develops prior to task failure, the increase in corticospinal excitability observed in relationship to the decrease in spinal excitability results from a combination of decreasing intracortical inhibition with constant levels of intracortical facilitation and upstream excitability that together eventually fail to provide the input to the motor cortex necessary for descending drive to overcome the spinal cord resistance, thereby contributing to task failure
Preliminary evidence that anodal transcranial direct current stimulation enhances time to task failure of a sustained submaximal contraction.
The purpose of this study was to determine whether anodal transcranial direct current stimulation (tDCS) delivered while performing a sustained submaximal contraction would increase time to task failure (TTF) compared to sham stimulation. Healthy volunteers (n = 18) performed two fatiguing contractions at 20% of maximum strength with the elbow flexors on separate occasions. During fatigue task performance, either anodal or sham stimulation was delivered to the motor cortex for up to 20 minutes. Transcranial magnetic stimulation (TMS) was used to assess changes in cortical excitability during stimulation. There was no systematic effect of the anodal tDCS stimulation on TTF for the entire subject set (n = 18; p = 0.64). Accordingly, a posteriori subjects were divided into two tDCS-time groups: Full-Time (n = 8), where TTF occurred prior to the termination of tDCS, and Part-Time (n = 10), where TTF extended after tDCS terminated. The TTF for the Full-Time group was 31% longer with anodal tDCS compared to sham (p = 0.04), whereas TTF for the Part-Time group did not differ (p = 0.81). Therefore, the remainder of our analysis addressed the Full-Time group. With anodal tDCS, the amount of muscle fatigue was 6% greater at task failure (p = 0.05) and the amount of time the Full-Time group performed the task at an RPE between 8–10 (“very hard”) increased by 38% (p = 0.04) compared to sham. There was no difference in measures of cortical excitability between stimulation conditions (p = 0.90). That the targeted delivery of anodal tDCS during task performance both increased TTF and the amount of muscle fatigue in a subset of subjects suggests that augmenting cortical excitability with tDCS enhanced descending drive to the spinal motorpool to recruit more motor units. The results also suggest that the application of tDCS during performance of fatiguing activity has the potential to bolster the capacity to exercise under conditions required to derive benefits due to overload
Modeling buoyant droplet plumes in a stratified environment
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.Includes bibliographical references (p. 138-146).This work describes the formulation and application of a novel two-phase integral plume model. This model describes the characteristics of a vertical plume driven by the continuous release of dissolving buoyant droplets from a fixed point in a stratified, stagnant environment. Model development is motivated by a specific application, the injection of CO 2 into the deep ocean by means of a buoyant droplet plume. This application is one method of sequestering anthropogenic C02 emissions from the atmosphere. The goal of such measures is to reduce the environmental risks associated with atmospheric emissions. Of course, sequestration of C02 in the ocean introduces other environmental concerns, as dissolved CO 2 tends to lower seawater pH. It is also necessary to ensure that the CO2 is delivered to a depth where it will not be transported to the surface over short time scales. To assess the feasibility and begin to estimate the potential for environmental impacts, a multinational group of researchers plans to conduct a pilot-scale field experiment in 2001. The aim of this work is to build a model of a buoyant droplet plume that will aid both design and interpretation of the field experiment, as well as any production-scale C02 releases. Such a model is also applicable to other two-phase plume flows. To that end, an integral model is formulated which accounts for the dynamics of the primary processes associated with a droplet plume: buoyant forces acting upon the droplets and plume water, dissolution of the droplets, turbulent entrainment of ambient water into the plume, and buoyant detrainment, or "peeling." The resulting model, at its core, is expressed as a set of nonlinear, coupled differential equations. Typical integral plume models are one-dimensional, initial-value problems which require a single integration to solve the governing equations. The particular nature of the class of plumes under investigation (droplet plumes where droplet buoyancy decreases with height due to dissolution, and dissolved C02 increases fluid density), however, is characterized by regions of upward flow, driven by the buoyant droplets, and downward flow, driven by stratification and other density effects. As these flows are coupled, solution of the governing equations for flow in each direction is iterative, increasing the complexity of the solution scheme. One implicit model assumption is that plume fluid in the vicinity of the droplets advects in the same direction as the droplets. As some coarse grid models predict that the fluid actually flows in the opposite direction, some scoping experiments were carried out to verify the nature of the velocity profile in a countercurrent droplet plume. The model is analyzed for sensitivity to both design variables, such as the flow rate of droplets at the source, and parameters which are uncertain, such as turbulent entrainment coefficients and droplet dissolution rates. In the case of C02 droplets, the dissolution rate is quite uncertain due to the formation of hydrates on the droplet surface, whose effect on mass transfer is poorly understood. Fortunately, it is clear that reduced mass transfer rates can be offset by reducing the size of the droplets. Also, while plume characteristics such as plume height are sensitive to parameter uncertainty, the dilution of C02 is strongly controlled by quantifiable factors such as the C02 mass flux and the ambient stratification. This is attributable to the density effect of dissolved C02; high concentrations of dissolved C02 creates negative buoyancy which induces mixing. This mixing aids dilution. The model is also compared to datasets describing different plume regimes in order to assess its validity. Though, when tuned to a given situation, the model agrees well with the data, there is no set of parameters which is universally applicable. Although the reasons why some parameters, such as the entrainment coefficients, change from case to case are partially understood, parameter uncertainty limits the accuracy of the model. In the case of a C02 droplet plume, the rise height predictions are estimated to be accurate to within ±30 percent.by Brian Crounse.S.M
On-site treatment of exertional heat stroke
Background: Exertional heat stroke is a devastating condition that can cause significant morbidity and mortality. Rapid cooling is the most effective means of treating heat stroke, but little is published on the safety and logistics of cooling patients on site at a major sporting event.
Purpose: To describe an on-site exertional heat stroke treatment protocol and to compare the outcomes of patients treated on site to those transferred to hospitals.
Study Design: Descriptive epidemiological study.
Methods: Using race-day medical records and ambulance run sheets, patients who developed exertional heat stroke at the Indianapolis half-marathon from 2005 to 2012 were identified. Exertional heat stroke was defined as runners with a core temperature measured with a rectal thermometer greater than 102°F and altered mental status. Clinical information and patient outcomes were abstracted from the race medical tent and hospital charts by 3 separate trained reviewers using structured methods and a data collection form. Two reviewers, using a RedCAP database and dual-data entry, abstracted records for each patient. A third arbitrated all discrepancies between reviewers. Clinical signs, treatments, and outcomes were calculated using descriptive statistics, and data were grouped and compared for patients treated on site or transferred to local hospitals for treatment.
Results: Over 235,000 athletes participated in the event over the 8-year period, with 696 seeking medical care. A total of 32 heat stroke victims were identified during the study period; of these, 22 were treated on site. Of these, 68% were treated with cold-water immersion and 59% were discharged home from the race. Ten exertional heat stroke patients were transported from the race course to local hospitals. None of them underwent cold-water immersion, and 40% of them were subsequently discharged home. No patients in the study died.
Conclusion: On-site treatment of athletes who develop exertional heat stroke appears to be both safe and effective. On-site treatment may decrease the local burden of critically ill patients to emergency departments during large athletic events
Sleeping time is associated with functional limitations in a national sample of older Americans
Background: Engaging in healthy behaviors may help to preserve function during aging; however, it is not well understood how sleeping time is associated with functional capacity in older adults.
Aims: We sought to determine the association of sleeping time on functional limitation in a national sample of older Americans.
Methods: The analytical sample included 6,020 adults aged at least 65 years who participated in the 2007-2016 waves of the National Health and Nutrition Examination Survey. Respondents indicated their hours of sleep/week night and were categorized as \u3c5, 5-6.5, 7-8, 8.5-9, and \u3e9 hours of sleep/week night. Ability to complete 19 functional tasks including basic activities of daily living, instrumental activities of daily living, leisure and social activities, lower extremity mobility activities, and general physical activities were also self-reported. A covariate-adjusted logistic model analyzed the associations between each sleeping time category and functional limitation.
Results: Relative to those reporting 7-8 hours of sleep/week night, older Americans reporting \u3c5, 5-6.5, 8.5-9, and \u3e9 hours of sleep/week night had 2.02 (95% confidence interval (CI): 1.26, 3.21), 1.25 (CI: 1.02, 1.53), 1.60 (CI: 1.21, 2.12), and 3.21 (CI: 2.12, 4.87) greater odds for functional limitation, respectively.
Discussion: Sleep should be recognized as a health factor that may reflect functional capacity in older adults. Healthcare providers should discuss the importance of optimal sleep with their older patients and older adults should practice healthy sleeping behaviors for preserving function.
Conclusions: Not meeting optimal sleep recommendations is associated with functional limitations in older Americans
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