9,759 research outputs found
Contribution of Intrinsic and Extrinsic Factors to Teacher Motivation
Teachers feel their work is becoming increasingly stressful and their status is falling leading to less job satisfaction with a concomitant loss in motivation. This study sought to find out in quantitative terms, the amount of motivation that the intrinsic and extrinsic socio-economic factors make to teacher motivation. The research design employed for this research is quasi-experimental. Two thousand and ninety-eight (2,098) teachers were selected from the Upper East Region of Ghana. Both quantitative and qualitative data was collected. The results showed that intrinsic and extrinsic socio-economic factors do motivate teachers in the execution of their work. However, not a strong association exist between teacher motivation and the intrinsic and extrinsic socio-economic variables. Not much of teacher motivation depends on socio-economic factors. Per the findings of the study, the association between the degree of motivation that teachers receive from the intrinsic and extrinsic socio-economic factors, MâŹ, and the percentage of respondents that claim they are motivated by the factors, fâŹ, could be represented by the polynomial relation, M⏠= ”3(fâŹ)3 - ”2(fâŹ)2 + ”1(fâŹ) - ”0. Intrinsic and extrinsic (socio-economic) factors cannot sustain the motivation of teachers permanently, even though the lack of them will lead to demotivation of teachers
Complex pattern of genetic structuring in the Atlantic salmon (Salmo salar L.) of the River Foyle system in northwest Ireland: disentangling the evolutionary signal from population stochasticity
Little is known about the microevolutionary processes shaping within river population genetic structure of aquatic organisms characterized by high levels of homing and spawning site fidelity. Using a microsatellite panel, we observed complex and highly significant levels of intrariver population genetic substructure and Isolation-by-Distance, in the Atlantic salmon stock of a large river system. Two evolutionary models have been considered explaining mechanisms promoting genetic substructuring in Atlantic salmon, the member-vagrant and metapopulation models. We show that both models can be simultaneously used to explain patterns and levels of population structuring within the Foyle system. We show that anthropogenic factors have had a large influence on contemporary population structure observed. In an analytical development, we found that the frequently used estimator of genetic differentiation, FST, routinely underestimated genetic differentiation by a factor three to four compared to the equivalent statistic Jost's Dest (Jost 2008). These statistics also showed a near-perfect correlation. Despite ongoing discussions regarding the usefulness of âadjustedâFST statistics, we argue that these could be useful to identify and quantify qualitative differences between populations, which are important from management and conservation perspectives as an indicator of existence of biologically significant variation among tributary populations or a warning of critical environmental damage
Toward Cooling Uniformity: Investigation of Spiral, Sweeping Holes, and Unconventional Cooling Paradigms
Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. Ways to quantify the efficacy of novel cooling holes that are asymmetric, not uniformly spaced or that show variation from hole to hole are presented. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and square holes. A patent-pending spiral hole design showed the highest potential of the nondiffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing ratios of 1.0, 1.5, 2.0, and 2.5 at a density ratio of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS. A section on ideas for future work is included that addresses issues of quantifying cooling uniformity and provides some ideas for changing the way we think about cooling such as changing the direction of cooling or coupling acoustic devices to cooling holes to regulate frequency
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Vitamin A Metabolism by Dendritic Cells Triggers an Antimicrobial Response against Mycobacterium tuberculosis.
Epidemiological evidence correlates low serum vitamin A (retinol) levels with increased susceptibility to active tuberculosis (TB); however, retinol is biologically inactive and must be converted into its bioactive form, all-trans retinoic acid (ATRA). Given that ATRA triggers a Niemann-Pick type C2 (NPC2)-dependent antimicrobial response against Mycobacterium tuberculosis, we investigated the mechanism by which the immune system converts retinol into ATRA at the site of infection. We demonstrate that granulocyte-macrophage colony-stimulating factor (GM-CSF)-derived dendritic cells (DCs), but not macrophages, express enzymes in the vitamin A metabolic pathway, including aldehyde dehydrogenase 1 family, member a2 (ALDH1A2) and short-chain dehydrogenase/reductase family, member 9 (DHRS9), enzymes capable of the two-step conversion of retinol into ATRA, which is subsequently released from the cell. Additionally, mRNA and protein expression levels of ALDH1A2 and DC marker CD1B were lower in tuberculosis lung tissues than in normal lung. The conditioned medium from DCs cultured with retinol stimulated antimicrobial activity from M. tuberculosis-infected macrophages, as well as the expression of NPC2 in monocytes, which was blocked by specific inhibitors, including retinoic acid receptor inhibitor (RARi) or N,N-diethylaminobenzaldehyde (DEAB), an ALDH1A2 inhibitor. These results indicate that metabolism of vitamin A by DCs transactivates macrophage antimicrobial responses.IMPORTANCE Tuberculosis (TB) is the leading cause of death by a single infectious agent worldwide. One factor that contributes to the success of the microbe is the deficiency in immunomodulatory nutrients, such as vitamin A (retinol), which are prevalent in areas where TB is endemic. Clinical trials show that restoration of systemic retinol levels in active TB patients is ineffective in mitigating the disease; however, laboratory studies demonstrate that activation of the vitamin A pathway in Mycobacterium tuberculosis-infected macrophages triggers an antimicrobial response. Therefore, the goal of this study was to determine the link between host retinol levels and retinoic acid-mediated antimicrobial responses against M. tuberculosis By combining established in vitro models with in situ studies of lung tissue from TB patients, this study demonstrates that the innate immune system utilizes transcellular metabolism leading to activation between dendritic cells and macrophages as a means to combat the pathogen
Quiescent adult neural stem cells are exceptionally sensitive to cosmic radiation
Generation of new neurons in the adult brain, a process that is likely to be essential for learning, memory, and mood regulation, is impaired by radiation. Therefore, radiation exposure might have not only such previously expected consequences as increased probability of developing cancer, but might also impair cognitive function and emotional stability. Radiation exposure is encountered in settings ranging from cancer therapy to space travel; evaluating the neurogenic risks of radiation requires identifying the at-risk populations of stem and progenitor cells in the adult brain. Here we have used a novel reporter mouse line to find that early neural progenitors are selectively affected by conditions simulating the space radiation environment. This is reflected both in a decrease in the number of these progenitors in the neurogenic regions and in an increase in the number of dying cells in these regions. Unexpectedly, we found that quiescent neural stem cells, rather than their rapidly dividing progeny, are most sensitive to radiation. Since these stem cells are responsible for adult neurogenesis, their death would have a profound impact on the production of new neurons in the irradiated adult brain. Our finding raises an important concern about cognitive and emotional risks associated with radiation exposure
Glioblastoma and Increased Survival with Longer Chemotherapy Duration
Introduction
The five-year survival rate for patients with glioblastoma (GBM) is low at approximately 4.7%. Radiotherapy plus concomitant and adjuvant temozolomide (TMZ) remains the standard of care. The optimal duration of therapy with TMZ is unknown. This study sought to evaluate the survival benefit of two years of treatment.
Methods
This was a retrospective chart review of all patients diagnosed with GBM and treated with TMZ for up to two years between January 1, 2002 and December 31, 2011. The Kaplan-Meier method with log-rank test was used to estimate the progression-free survival (PFS) and the overall survival (OS). The results were compared to historical controls and data from previous clinical trials of patients treated up to one year.
Results
Data from 56 patients with confirmed GBM were evaluated. The OS probability was 54% (SE = 0.068) at one year, 28.3% (SE = 0.064) at two years, 17.8% (SE = 0.059) at three years, and 4% (SE = 0.041) at five years. Seven patients (12.5%) were treated with TMZ for two years. Their median time-to-progression was 28 months (95% CI = 5.0 - 28.0), and they had an increased survival probability at three years compared to other patients (log-rank test Ï2 (1, N = 56) = 19.2, p < 0.0001).
Conclusions
There may be an advantage for a longer duration of TMZ therapy among patients with GBM, but the sample size was too small for generalization. A multicenter prospective study is needed to dentify optimal duration of TMZ therapy
A Guide for Using NIH Image J for Single Slice Cross-Sectional Area and Composition Analysis of the Thigh from Computed Tomography
Reports using computed tomography (CT) to estimate thigh skeletal muscle cross-sectional area and mean muscle attenuation are often difficult to evaluate due to inconsistent methods of quantification and/or poorly described analysis methods. This CT tutorial provides step-by-step instructions in using free, NIH Image J software to quantify both muscle size and composition in the mid-thigh, which was validated against a robust commercially available software, SliceOmatic. CT scans of the mid-thigh were analyzed from 101 healthy individuals aged 65 and older. Mean cross-sectional area and mean attenuation values are presented across seven defined Hounsfield unit (HU) ranges along with the percent contribution of each region to the total mid-thigh area. Inter-software correlation coefficients ranged from R2 = 0.92â0.99 for all specific area comparisons measured using the Image J method compared to SliceOmatic. We recommend reporting individual HU ranges for all areas measured. Although HU range 0â100 includes the majority of skeletal muscle area, HU range -29 to 150 appears to be the most inclusive for quantifying total thigh muscle. Reporting all HU ranges is necessary to determine the relative contribution of each, as they may be differentially affected by age, obesity, disease, and exercise. This standardized operating procedure will facilitate consistency among investigators reporting computed tomography characteristics of the thigh on single slice images.
Trial Registration: ClinicalTrials.gov NCT02308228
Polls and the political process: the use of opinion polls by political parties and mass media organizations in European postâcommunist societies (1990â95)
Opinion polling occupies a significant role within the political process of most liberal-capitalist societies, where it is used by governments, parties and the mass media alike. This paper examines the extent to which polls are used for the same purposes in the post-communist countries of Central and Eastern Europe, and in particular, for bringing political elites and citizens together. It argues that these political elites are more concerned with using opinion polls for gaining competitive advantage over their rivals and for reaffirming their political power, than for devolving political power to citizens and improving the general processes of democratization
Space Exploration: A Risk for Neural Stem Cells
During spaceflights beyond low Earth orbit, astronauts are exposed to potentially carcinogenic and tissue damaging galactic cosmic rays, solar proton events, and secondary radiation that includes neutrons and recoil nuclei produced by nuclear reactions in spacecraft walls or in tissue (1). Such radiation risk may present a significant health risk for human exploration of the moon and Mars. Emerging evidence that generation of new neurons in the adult brain may be essential for learning, memory, and mood (2) and that radiation is deleterious to neurogenesis (3-5) underscores a previously unappreciated possible risk to the cognitive functions and emotional stability of astronauts exposed to radiation in space. Here we use a novel reporter mouse line to identify at-risk populations of stem and progenitor cells in the brain and find, unexpectedly, that quiescent stem-like cells (rather than their rapidly dividing progeny) in the hippocampus constitute the most vulnerable cell population. This finding raises concerns about the possible risks facing astronauts on long duration space missions
A tangled start:The link between childhood maltreatment, psychopathology, and relationships in adulthood
Background: Adults with a history of childhood maltreatment are more likely to experience distrust, feel distant from others, and develop an insecure attachment style which may also affect relationship quality. Furthermore, childhood maltreatment has been linked to several mental health problems; including, depression, anxiety, and alcohol dependance severity, that are also known to relationship quality. Objective: The current study was designed to investigate to what extent childhood maltreatment is associated with adult insecure attachment and intimate relationships and whether this association is mediated by psychopathology. Participants and Method: In a study comprised of 2035 adults aged 18-65, we investigated whether childhood maltreatment was associated with insecure adult attachment styles and the quality of intimate relationships and whether this was mediated by depression, anxiety, and alcohol dependence severity (based on repeated assessments of the Inventory of Depressive Symptomatology-Self Report, Beck Anxiety Index, and Alcohol Use Disorders Identification Test respectively). Results: The path model showed an acceptable fit, RMSEA = 0.05, and suggested full mediation of the association of childhood maltreatment with quality of intimate relationships by depression severity and a) anxious attachment (13 = -4.0 * 10-2; 95% CI = -5.5 * 10-2, -2.7 * 10-2) and b) avoidant attachment (13 = -7.2 * 10-2; 95% CI = -9.6 * 10-2, -4.9 * 10-2). Anxiety and alcohol dependence severity were not significant mediators. Conclusions: Childhood maltreatment is associated with a lower quality of intimate relationships, which is fully mediated by depression severity and insecure attachment styles.Prevention, Population and Disease management (PrePoD)Public Health and primary car
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