2,024 research outputs found
Supporting Peer Help and Collaboration in Distributed Workplace Environments
Special Issue on Computer Supported Collaborative LearningIncreasingly, organizations are geographically distributed with activities coordinated and integrated through the use of information technology. Such organizations face constant change and the corresponding need for continual learning and renewal of their workers. In this paper we describe a prototype system called PHelpS (Peer Help System) that facilitates workers in carrying out such "life long learning". PHelpS supports workers as they perform their tasks, offers assistance in finding peer helpers when required, and mediates communication on task-related topics. When a worker runs into difficulty in carrying out a task, PHelpS provides a list of other workers who are ready, willing and able to help him or her. The worker then selects a particular helper with PHelpS supporting the subsequent help interaction. The PHelpS system acts as a facilitator to stimulate learning and collaboration, rather than as a directive agent imposing its perspectives on the workers. In this way PHelpS facilitates the creation of extensive informal peer help networks, where workers help one another with tasks and opens up new research avenues for further exploration of AI-based computer-supported collaborative learning. (http://aied.inf.ed.ac.uk/members98/archive/vol_9/greer/full.html
The spread of influenza A(H1N1)pdm09 in Victorian school children in 2009:iImplications for revised pandemic planning
Background
Victoria was the first state in Australia to experience community transmission of influenza A(H1N1)pdm09. We undertook a descriptive epidemiological analysis of the first 1,000 notified cases to describe the epidemic associated with school children and explore implications for school closure and antiviral distribution policy in revised pandemic plans.
Methods
Records of the first 1,000 laboratory-confirmed cases of influenza A(H1N1)pdm09 notified to the Victorian Government Department of Health between 20 May and 5 June 2009 were extracted from the stateâs notifiable infectious diseases database. Descriptive analyses were conducted on case demographics, symptoms, case treatment, prophylaxis of contacts and distribution of cases in schools.
Results
Two-thirds of the first 1,000 cases were school-aged (5â17 years) with cases in 203 schools, particularly along the north and western peripheries of the metropolitan area. Cases in one school accounted for nearly 8% of all cases but the school was not closed until nine days after symptom onset of the first identified case. Amongst all cases, cough (85%) was the most commonly reported symptom followed by fever (68%) although this was significantly higher in primary school children (76%). The risk of hospitalisation was 2%. The median time between illness onset and notification of laboratory confirmation was four days, with only 10% of cases notified within two days of onset and thus eligible for oseltamivir treatment. Nearly 6,000 contacts were followed up for prophylaxis.
Conclusions
With a generally mild clinical course and widespread transmission before its detection, limited and short-term school closures appeared to have minimal impact on influenza A(H1N1)pdm09 transmission. Antiviral treatment could rarely be delivered to cases within 48 hours of symptom onset. These scenarios and lessons learned from them need to be incorporated into revisions of pandemic plans
Mineral deposition and vascular invasion of hydroxyapatite reinforced collagen scaffolds seeded with human adipose-derived stem cells
Background:
Collagen-based scaffolds reinforced with hydroxyapatite (HA) are an attractive choice for bone tissue engineering because their composition mimics that of bone. We previously reported the development of compression-molded collagen-HA scaffolds that exhibited high porosity, interconnected pores, and mechanical properties that were well-suited for surgical handling and fixation. The objective of this study was to investigate these novel collagen-HA scaffolds in combination with human adipose-derived stem cells (hASCs) as a template for bone formation in a subcutaneous athymic mouse model.
Methods:
Collagen-HA scaffolds and collagen-only scaffolds were fabricated as previously described, and a clinically approved bone void filler was used as a control for the material. Constructs were seeded with hASCs and were pre-treated with either control or osteogenic media. A cell-free group was also included. Scaffolds were implanted subcutaneously in the backs of athymic nude mice for 8âweeks. Mineral deposition was quantified via micro-computed tomography. Histological and immunofluorescence images of the explants were used to analyze their vascular invasion, remodeling and cellularity.
Results:
Cell-free collagen-HA scaffolds and those that were pre-seeded with osteogenically differentiated hASCs supported mineral deposition and vascular invasion at comparable rates, while cell-seeded constructs treated with the control medium showed lower mineralization after implantation. HA-reinforcement allowed collagen constructs to maintain their shape, provided improved cell-tissue-scaffold integration, and resulted in a more organized tissue when pre-treated in an osteogenic medium. Scaffold type and pre-treatment also determined osteoclast activity and therefore potential remodeling of the constructs.
Conclusions:
The results of this study cumulatively indicate that treatment medium and scaffold composition direct mineralization and angiogenic tissue formation in an ectopic model. The data suggest that it may be necessary to match the scaffold with a particular cell type and cell-specific pre-treatment to achieve optimal bone formation
Nighttime removal of NOx in the summer marine boundary layer
The nitrate radical, NO3, and dinitrogen pentoxide, N2O5, are two important components of nitrogen oxides that occur predominantly at night in the lower troposphere. Because a large fraction of NO2 reacts to form NO3 and N2O5 during the course of a night, their fate is an important determining factor to the overall fate of NOx (=NO and NO2). As a comprehensive test of nocturnal nitrogen oxide chemistry, concentrations of O3, NO, NO2, NO3, N2O5, HNO3 and a host of other relevant compounds, aerosol abundance and composition, and meteorological conditions were measured in the marine boundary layer from the NOAA research vessel Ronald H. Brown off the East Coast of the United States as part of the New England Air Quality Study (NEAQS) during the summer of 2002. The results confirm the prominent role of NO3 and N2O5 in converting NOx to HNO3 at night with an efficiency on par with daytime photochemical conversion. The findings demonstrate the large role of nighttime chemistry in determining the NOx budget and consequent production of ozone. INDEX TERMS: 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0345 Atmospheric Composition and Structure: Pollutionâurban and regional (0305); 0365 Atmospheric Composition and Structure: Troposphereâcomposition and chemistry. Citation: Brown, S. S., et al. (2004), Nighttime removal of NOx in the summer marine boundary layer, Geophys. Res. Lett., 31, L07108, doi:10.1029/2004GL01941
On handling urban informality in southern Africa
In this article I reconsider the handling of urban informality by urban planning and management systems in southern Africa. I argue that authorities have a fetish about formality and that this is fuelled by an obsession with urban modernity. I stress that the desired city, largely inspired by Western notions of modernity, has not been and cannot be realized. Using illustrative cases of topâdown interventions, I highlight and interrogate three strategies that authorities have deployed to handle informality in an effort to create or defend the modern city. I suggest that the fetish is built upon a desire for an urban modernity based on a concept of formal order that the authorities believe cannot coexist with the âdisorderâ and spatial âunrulinessâ of informality. I question the authorities' conviction that informality is an abomination that needs to be âconvertedâ, dislocated or annihilated. I conclude that the very configuration of urban governance and socio-economic systems in the region, like the rest of sub-Saharan Africa, renders informality inevitable and its eradication impossible
End-of-Life Delirium: Issues Regarding Recognition, Optimal Management and the Role of Sedation in the Dying Phase.
CONTEXT:
In end-of-life care, delirium is often not recognized and poses unique management challenges, especially in the case of refractory delirium in the terminal phase. OBJECTIVES:
To review: delirium in the terminal phase context, specifically in relation to recognition issues; the decision-making processes and management strategies regarding its reversibility; the potential refractoriness of delirium to symptomatic treatment; and the role of sedation in refractory delirium. METHODS:
We combined multidisciplinary input from delirium researchers and knowledge users at an international delirium study planning meeting and relevant electronic database literature searches (Ovid Medline, Embase, PsycINFO and CINAHL) to inform this narrative review. RESULTS:
The overall management strategy for delirium at the end of life is directed by the patient\u27s prognosis in association with the patient\u27s goals of care. As symptoms of delirium are often refractory in the terminal phase, especially in the case of agitated delirium, the judicious use of palliative sedation is frequently required. However, there remains a lack of high level evidence for the management of delirium in the terminal phase, including the role of antipsychotics and optimal sedation strategies. For the family and health care staff, clear communication, education and emotional support are vital components to assist with decision making and direct the treatment care plan. CONCLUSION:
Further research on the effectiveness of delirium management strategies in the terminal phase for patients and their families is required. Further validation of assessment tools for diagnostic screening and severity measurement are needed in this patient population
Optimizing end-labeled free-solution electrophoresis by increasing the hydrodynamic friction of the drag-tag
We study the electrophoretic separation of polyelectrolytes of varying
lengths by means of end-labeled free-solution electrophoresis (ELFSE). A
coarse-grained molecular dynamics simulation model, using full electrostatic
interactions and a mesoscopic Lattice Boltzmann fluid to account for
hydrodynamic interactions, is used to characterize the drag coefficients of
different label types: linear and branched polymeric labels, as well as
transiently bound micelles.
It is specifically shown that the label's drag coefficient is determined by
its hydrodynamic size, and that the drag per label monomer is largest for
linear labels. However, the addition of side chains to a linear label offers
the possibility to increase the hydrodynamic size, and therefore the label
efficiency, without having to increase the linear length of the label, thereby
simplifying synthesis. The third class of labels investigated, transiently
bound micelles, seems very promising for the usage in ELFSE, as they provide a
significant higher hydrodynamic drag than the other label types.
The results are compared to theoretical predictions, and we investigate how
the efficiency of the ELFSE method can be improved by using smartly designed
drag-tags.Comment: 32 pages, 11 figures, submitted to Macromolecule
Green Plants in the Red: A Baseline Global Assessment for the IUCN Sampled Red List Index for Plants
Plants provide fundamental support systems for life on Earth and are the basis for all terrestrial ecosystems; a decline in plant diversity will be detrimental to all other groups of organisms including humans. Decline in plant diversity has been hard to quantify, due to the huge numbers of known and yet to be discovered species and the lack of an adequate baseline assessment of extinction risk against which to track changes. The biodiversity of many remote parts of the world remains poorly known, and the rate of new assessments of extinction risk for individual plant species approximates the rate at which new plant species are described. Thus the question âHow threatened are plants?â is still very difficult to answer accurately. While completing assessments for each species of plant remains a distant prospect, by assessing a randomly selected sample of species the Sampled Red List Index for Plants gives, for the first time, an accurate view of how threatened plants are across the world. It represents the first key phase of ongoing efforts to monitor the status of the worldâs plants. More than 20% of plant species assessed are threatened with extinction, and the habitat with the most threatened species is overwhelmingly tropical rain forest, where the greatest threat to plants is anthropogenic habitat conversion, for arable and livestock agriculture, and harvesting of natural resources. Gymnosperms (e.g. conifers and cycads) are the most threatened group, while a third of plant species included in this study have yet to receive an assessment or are so poorly known that we cannot yet ascertain whether they are threatened or not. This study provides a baseline assessment from which trends in the status of plant biodiversity can be measured and periodically reassessed
A Search for Very High-Energy Gamma Rays from the Missing Link Binary Pulsar J1023+0038 with VERITAS
The binary millisecond radio pulsar PSR J1023+0038 exhibits many
characteristics similar to the gamma-ray binary system PSR B1259--63/LS 2883,
making it an ideal candidate for the study of high-energy non-thermal emission.
It has been the subject of multi-wavelength campaigns following the
disappearance of the pulsed radio emission in 2013 June, which revealed the
appearance of an accretion disk around the neutron star. We present the results
of very high-energy gamma-ray observations carried out by VERITAS before and
after this change of state. Searches for steady and pulsed emission of both
data sets yield no significant gamma-ray signal above 100 GeV, and upper limits
are given for both a steady and pulsed gamma-ray flux. These upper limits are
used to constrain the magnetic field strength in the shock region of the PSR
J1023+0038 system. Assuming that very high-energy gamma rays are produced via
an inverse-Compton mechanism in the shock region, we constrain the shock
magnetic field to be greater than 2 G before the disappearance of the
radio pulsar and greater than 10 G afterwards.Comment: 7 pages, 3 figures, accepted for publication in Ap
Flavones induce neutrophil apoptosis by down-regulation of Mcl-1 via a proteasomal-dependent pathway
Neutrophil apoptosis and subsequent nonphlogistic clearance by surrounding phagocytes are key to the successful resolution of neutrophilic inflammation, with dysregulated apoptosis reported in multiple human inflammatory diseases. Enhancing neutrophil apoptosis has proresolution and anti-inflammatory effects in preclinical models of inflammation. Here we investigate the ability of the flavones apigenin, luteolin, and wogonin to induce neutrophil apoptosis in vitro and resolve neutrophilic inflammation in vivo. Human neutrophil apoptosis was assessed morphologically and by flow cytometry following incubation with apigenin, luteolin, and wogonin. All three flavones induced time- and concentration-dependent neutrophil apoptosis (apigenin, EC(50)=12.2 ÎŒM; luteolin, EC(50)=14.6 ÎŒM; and wogonin, EC(50)=28.9 ÎŒM). Induction of apoptosis was caspase dependent, as it was blocked by the broad-spectrum caspase inhibitor Q-VD-OPh and was associated with both caspase-3 and caspase-9 activation. Flavone-induced apoptosis was preceded by down-regulation of the prosurvival protein Mcl-1, with proteasomal inhibition preventing flavone-induced Mcl-1 down-regulation and apoptosis. The flavones abrogated the survival effects of mediators that prolong neutrophil life span, including lipoteichoic acid, peptidoglycan, dexamethasone, and granulocyte-macrophage colony stimulating factor, by driving apoptosis. Furthermore, wogonin enhanced resolution of established neutrophilic inflammation in a zebrafish model of sterile tissue injury. Wogonin-induced resolution was dependent on apoptosis in vivo as it was blocked by caspase inhibition. Our data show that the flavones induce neutrophil apoptosis and have potential as neutrophil apoptosis-inducing anti-inflammatory, proresolution agents.âLucas, C. D., Allen, K. C., Dorward, D. A., Hoodless, L. J., Melrose, L. A., Marwick, J. A., Tucker, C. S., Haslett, C., Duffin, R., Rossi, A. G. Flavones induce neutrophil apoptosis by down-regulation of Mcl-1 via a proteasomal-dependent pathway
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