1,823 research outputs found
Investigation of environmental effects on coatings for thermal control
Accomplishments made during study of coatings are reported. Development of structure/property theory for selecting most appropriate pigments for space vehicle paints is discussed along with improvements made in zinc-oxide pigmented potassium silicate paint
Development of a space stable thermal control coatings for use in large space vehicles
The preparation and evaluation of zinc orthotitanate and of several new pigments and the environmental testing and evaluation of these pigments and of coatings made from them constitute the bulk of the work accomplished. New pigments were prepared and EPR spectra of pigments and their precursor compounds studied. Results of extensive testing of commercially-available, strippable, protective coatings are reported; Owens-Illinois 650 glass resin has been stabilized against progressive mechanical failures; and definite improvements have been noted. A zinc oxide pigmented lithium silicate paint has demonstrated very good ultraviolet stability
Development of space stable thermal control coatings for use on large space vehicles
The evaluation and environmental testing of zinc orthotitanate pigments for use as space stable thermal control coatings on large space vehicles are discussed. Electron paramagnetic resonance spectra of the pigments and their precursor compounds are examined. A continuing study of the spectral intensity of mercury-argon and mercury-xenon sources in reported. Results of long term environmental testing of commercially available, strippable, protective coatings are discussed
Clinical Characterization of Alzheimer's Disease: Reliability of 'Age at Onset' and a New Descriptor, 'Age at Shift'
To determine the interrater reliability of clinical descriptors for Alzheimer's disease (AD), we assessed the degree of agree ment among four clinicians who rated 21 patients during a longitudinal study. Despite variability in response patterns, degree of agreement for determining age at onset of dementia was statistically significant (P < 0.005). We also found significant agreement (P < 0.0001) among three clinicians for the clinical descriptor, "age at shift" from questionable to probable AD, according to the National Institutes of Health Consensus Criteria. These data demonstrate that both retro spective and prospective descriptors can be reliably determined in the clinical assessment of AD. (J Geriatr Psychiatry Neurol 1988;1:207-211).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68908/2/10.1177_089198878800100404.pd
Age and Growth of Scotia Sea Icefish, Chaenocephalus aceratus, From the South Shetland Islands
Samples of Chaenocephalus aceratus (Lönnberg) were collected during a trawl survey carried out around the South Shetland Islands in January–February 2002. Fish were caught by commercial bottom trawl fishing down to 500 m depth, using a stratified randomized sampling design. As observed in other recent surveys within the same area, C. aceratus represented one of the predominant species. Overall, 357 specimens ranging from 13 and 67 cm (TL) were selected for the present study. Ages were estimated by counting annuli present in the sagittal otoliths, exposed by grinding and polishing along their sagittal plane. To estimate the precision of age data, we compared blind readings by readers from different institutions. The age range was 1–17 years for females and 1–15 years for males. Von Bertalanffy growth curves were fitted to the estimated age-length data for each sex. The estimated values of asymptotic length L∞ (cm) and K (year-1) were respectively 79.8 and 0.07 for females and 60.0 and 0.09 for males. The growth performance index ranged between 2 and 2.5, similar to that reported in other icefish. Sexual maturity was attained by females and males at about 10 and 9 years old respectively, at about 60% of their maximum estimated age. These results are compared with age and growth data available in the literature for C. aceratus, and discussed in the light of recent commercial exploitation
Voice Flows To And Around Leaders: Understanding When Units Are Helped Or Hurt By Employee Voice
In two studies, we develop and test theory about the relationship between speaking up, one type of organizational citizenship behavior, and unit performance by accounting for where employee voice is flowing. Results from a qualitative study of managers and professionals across a variety of industries suggest that voice to targets at different formal power levels (peers or superiors) and locations in the organization (inside or outside a focal unit) differs systematically in terms of its usefulness in generating actions to a unit's benefit on the issues raised and in the likely information value of the ideas expressed. We then theorize how distinct voice flows should be differentially related to unit performance based on these core characteristics and test our hypotheses using time-lagged field data from 801 employees and their managers in 93 units across nine North American credit unions. Results demonstrate that voice flows are positively related to a unit's effectiveness when they are targeted at the focal leader of that unitwho should be able to take actionwhether from that leader's own subordinates or those in other units, and negatively related to a unit's effectiveness when they are targeted at coworkers who have little power to effect change. Together, these studies provide a structural framework for studying the nature and impact of multiple voice flows, some along formal reporting lines and others that reflect the informal communication structure within organizations. This research demonstrates that understanding the potential performance benefits and costs of voice for leaders and their units requires attention to the structure and complexity of multiple voice flows rather than to an undifferentiated amount of voice.Business Administratio
Proactivity with image in mind: How employee and manager characteristics affect evaluations of proactive behaviours
This paper investigates image cost as a potential downside of proactivity. Drawing on attribution theory, we examine how people construct subjective evaluations of one manifestation of proactivity, feedback-seeking behaviour. Using a scenario methodology, we examined how employees' performance history, their manager's implicit person theory (IPT), and the frequency of their feedback-seeking affect how managers evaluate employees' feedback seeking. Results indicate that manager attribute average performers' feedback seeking significantly less to performance-enhancement motives than superior performers' seeking. Results further show that the frequency of feedback seeking and a manager's IPT interact in influencing managers' attributions for feedback seeking, with more entity oriented managers attributing frequent feedback seeking significantly more to impression-management motives than infrequent feedback requests. These results highlight the importance of not only the instrumental benefits of employee proactivity, but also its potential costs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79279/1/096317909X479529.pd
Mouse hypothalamic GT1-7 cells demonstrate AMPK-dependent intrinsic glucose-sensing behaviour.
AIMS/HYPOTHESIS: Hypothalamic glucose-excited (GE) neurons contribute to whole-body glucose homeostasis and participate in the detection of hypoglycaemia. This system appears defective in type 1 diabetes, in which hypoglycaemia commonly occurs. Unfortunately, it is at present unclear which molecular components required for glucose sensing are produced in individual neurons and how these are functionally linked. We used the GT1-7 mouse hypothalamic cell line to address these issues. METHODS: Electrophysiological recordings, coupled with measurements of gene expression and protein levels and activity, were made from unmodified GT1-7 cells and cells in which AMP-activated protein kinase (AMPK) catalytic subunit gene expression and activity were reduced. RESULTS: Hypothalamic GT1-7 neurons express the genes encoding glucokinase and ATP-sensitive K(+) channel (K(ATP)) subunits K ( ir ) 6.2 and Sur1 and exhibit GE-type glucose-sensing behaviour. Lowered extracellular glucose concentration hyperpolarised the cells in a concentration-dependent manner, an outcome that was reversed by tolbutamide. Inhibition of glucose uptake or metabolism hyperpolarised cells, showing that energy metabolism is required to maintain their resting membrane potential. Short hairpin (sh)RNA directed to Ampkα2 (also known as Prkaa2) reduced GT1-7 cell AMPKα2, but not AMPKα1, activity and lowered the threshold for hypoglycaemia-induced hyperpolarisation. shAmpkα1 (also known as Prkaa1) had no effect on glucose-sensing or AMPKα2 activity. Decreased uncoupling protein 2 (Ucp2) mRNA was detected in AMPKα2-reduced cells, suggesting that AMPKα2 regulates UCP2 levels. CONCLUSIONS/INTERPRETATION: We have demonstrated that GT1-7 cells closely mimic GE neuron glucose-sensing behaviour, and reducing AMPKα2 blunts their responsiveness to hypoglycaemic challenge, possibly by altering UCP2 activity. These results show that suppression of AMPKα2 activity inhibits normal glucose-sensing behaviour and may contribute to defective detection of hypoglycaemia.This study was funded by: grants from the Wellcome Trust
(grant numbers 068692 and 086989) and Diabetes UK (grant number
RD08/0003681) to M.L.J. Ashford; a Juvenile Diabetes Research
Foundation (JDRF) Postdoctoral Fellowship to C. Beall (grant number
3-576-2010); grants from JDRF and European Foundation for the
study of Diabetes to R.J. McCrimmon, and from the British Heart
Foundation to A. Jovanović
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Disability in Basic Activities of Daily Living Is Associated With Symptom Burden in Older People With Advanced Cancer or Chronic Obstructive Pulmonary Disease: A Secondary Data Analysis.
CONTEXT: Managing activities of daily living is important to people with advanced cancer or chronic obstructive pulmonary disease (COPD). Understanding disability in activities of daily living may inform service planning. OBJECTIVE: To identify the prevalence of disability in activities of daily living, associations and change over time, in older people with advanced cancer or COPD. METHODS: Secondary analysis of International Access, Rights and Empowerment (IARE) studies in adults aged ≥65 years with advanced disease in the United Kingdom, Ireland, and United States, using cross-sectional (IARE I & II) and longitudinal (IARE II, 3 timepoints over 6 months) data. Measures included disability in activities of daily living (Barthel Index), symptom severity (Palliative Outcome Scale), and assistive device use (self-reported). Logistic regression was used to identify relationships between disability and age, sex, living alone, diagnosis, and symptom burden; visual graphical analysis explores individual disability trajectories. RESULTS: One hundred fifty-nine participants were included (140 cancer, 19 COPD). Sixty-five percent had difficulty climbing stairs, 48% bathing, 39% dressing, and 36% mobilizing. Increased disability was independently associated with increased symptom burden (odds ratio, 1.08 [95% CI:1.02-1.15], P = 0.01) and walking unaided (z = 2.35, P = 0.02), but not with primary diagnosis (z = -0.47, P = 0.64). Disability generally increased over time but with wide interindividual variation. CONCLUSION: Disability in activities of daily living in advanced cancer or COPD is common, associated with increased symptom burden, and may be attenuated by use of assistive devices. Individual disability trajectories vary widely, with diverse disability profiles. Services should include rehabilitative interventions, guided by disability in individual activities of daily living
Avian malaria is absent in juvenile colonial herons (Ardeidae) but not Culex pipiens mosquitoes in the Camargue, Southern France
Apicomplexan blood parasites Plasmodium and Haemoproteus (together termed “Avian malaria”) and Leucocytozoon are widespread, diverse vector-transmitted blood parasites of birds, and conditions associated with colonial nesting in herons (Ardeidae) and other waterbirds appear perfect for their transmission. Despite studies in other locations reporting high prevalence of parasites in juvenile herons, juvenile Little Egrets (Egretta garzetta) previously tested in the Camargue, Southern France, had a total absence of malaria parasites. This study tested the hypotheses that this absence was due to insufficient sensitivity of the tests of infection; an absence of infective vectors; or testing birds too early in their lives. Blood was sampled from juveniles of four species shortly before fledging: Little Egret (n = 40), Cattle Egret (Bubulcus ibis; n = 40), Black-crowned Night-Heron (Nycticorax nycticorax, n = 40), and Squacco Heron (Ardeola ralloides; n = 40). Sensitive nested-Polymerase Chain Reaction was used to test for the presence of parasites in both birds and host-seeking female mosquitoes captured around the colonies. No malaria infection was found of in any of the heron species. Four different lineages of Plasmodium were detected in pooled samples of female Culex pipiens mosquitoes, including two in potentially infective mosquitoes. These results confirm that the absence of malaria parasites previously demonstrated in Little Egret is not due to methodological limitations. Although the prevalence of infection in mosquitoes was low, conditions within the colonies were suitable for transmission of Plasmodium. These colonial heron species may have evolved strategies for resisting malaria infection through physiological or behavioral mechanisms
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