2,154 research outputs found
Future Possibilities for Observing HI at High Redshift
We briefly review the beginnings of HI astronomy, proceed to an assessment of
our current capabilities in this area, and continue by considering what will be
necessary to push back the frontier to cosmological distances. We then consider
how such a leap in performance might be realized.Comment: 8 page LaTeX requires crckapb.sty and psfig.sty, 9 compressed and
tarred postscript figures (750kB) available at
ftp://ftp.nfra.nl/pub/outgoing/rbraun/futposhi/figs.tar.Z Complete compressed
postscript paper (790kB) available at
ftp://ftp.nfra.nl/pub/outgoing/rbraun/futposhi/paper.ps.Z To appear in "Cold
Gas at High Redshift", Eds. M.Bremer et al. (Kluwer, Dordrecht
Fisheries in the Development of Indian Economy
Fisheries sector plays a vital role in Indian economy through substantial forex earnings, employment generation and
ensuring nutritional and food security. Contribution of fisheries to total Gross Domestic Product (GDP) at current prices is about
1.3 percent. The fisheries economy of our country has undergone rapid structural changes during the last few decades. The vast
technological options available to fishers led them for a fast shift from traditional to mechanised and motorised fishing methods
in marine fisheries and from traditional to improved seed production and culture practices in inland fisheries
Testing Ecological Theory with Lianas
Lianas constitute a diverse polyphyletic plant group that is advancing our understanding of ecological theory. Specifically, lianas are providing new insights into the mechanisms that control plant distribution and diversity maintenance. For example, there is now evidence that a single, scalable mechanism may explain local, regional, and pan‐tropical distribution of lianas, as well as the maintenance of liana species diversity. The ability to outcompete trees under dry, stressful conditions in seasonal forests provides lianas a growth advantage that, over time, results in relatively high abundance in seasonal forests and low abundance in aseasonal forests. Lianas may also gain a similar growth advantage following disturbance, thus explaining why liana density and diversity peak following disturbance at the local, forest scale. The study of ecology, however, is more than the effect of the environment on organisms; it also includes the effects of organisms on the environment. Considerable empirical evidence now indicates that lianas substantially alter their environment by consuming resources, suppressing tree performance, and influencing emergent properties of forests, such as ecosystem functioning, plant and animal diversity, and community composition. These recent studies using lianas are transcending classical tropical ecology research and are now providing novel insights into fundamental ecological theory
A method for sensitivity analysis to assess the effects of measurement error in multiple exposure variables using external validation data
Measurement error in self-reported dietary intakes is known to bias the association between dietary intake and a health outcome of interest such as risk of a disease. The association can be distorted further by mismeasured confounders, leading to invalid results and conclusions. It is, however, difficult to adjust for the bias in the association when there is no internal validation data
Graveyards on the Move: The Spatio-Temporal Distribution of Dead Ophiocordyceps-Infected Ants
Parasites are likely to play an important role in structuring host populations. Many adaptively manipulate host behaviour, so that the extended phenotypes of these parasites and their distributions in space and time are potentially important ecological variables. The fungus Ophiocordyceps unilateralis, which is pan-tropical in distribution, causes infected worker ants to leave their nest and die under leaves in the understory of tropical rainforests. Working in a forest dynamic plot in Southern Thailand we mapped the occurrence of these dead ants by examining every leaf in 1,360 m2 of primary rainforest. We established that high density aggregations exist (up to 26 dead ants/m2), which we coined graveyards. We further established that graveyards are patchily distributed in a landscape with no or very few O. unilateralis-killed ants. At some, but not all, spatial scales of analysis the density of dead ants correlated with temperature, humidity and vegetation cover. Remarkably, having found 2243 dead ants inside graveyards we only found 2 live ants of the principal host, ant Camponotus leonardi, suggesting that foraging host ants actively avoid graveyards. We discovered that the principal host ant builds nests in high canopy and its trails only occasionally descend to the forest floor where infection occurs. We advance the hypothesis that rare descents may be a function of limited canopy access to tree crowns and that resource profitability of such trees is potentially traded off against the risk of losing workers due to infection when forest floor trails are the only access routes. Our work underscores the need for an integrative approach that recognises multiple facets of parasitism, such as their extended phenotypes
Insights into the Mechanism of Bovine CD38/NAD+Glycohydrolase from the X-Ray Structures of Its Michaelis Complex and Covalently-Trapped Intermediates
Bovine CD38/NAD+glycohydrolase (bCD38) catalyses the hydrolysis of NAD+ into nicotinamide and ADP-ribose and the formation of cyclic ADP-ribose (cADPR). We solved the crystal structures of the mono N-glycosylated forms of the ecto-domain of bCD38 or the catalytic residue mutant Glu218Gln in their apo state or bound to aFNAD or rFNAD, two 2′-fluorinated analogs of NAD+. Both compounds behave as mechanism-based inhibitors, allowing the trapping of a reaction intermediate covalently linked to Glu218. Compared to the non-covalent (Michaelis) complex, the ligands adopt a more folded conformation in the covalent complexes. Altogether these crystallographic snapshots along the reaction pathway reveal the drastic conformational rearrangements undergone by the ligand during catalysis with the repositioning of its adenine ring from a solvent-exposed position stacked against Trp168 to a more buried position stacked against Trp181. This adenine flipping between conserved tryptophans is a prerequisite for the proper positioning of the N1 of the adenine ring to perform the nucleophilic attack on the C1′ of the ribofuranoside ring ultimately yielding cADPR. In all structures, however, the adenine ring adopts the most thermodynamically favorable anti conformation, explaining why cyclization, which requires a syn conformation, remains a rare alternate event in the reactions catalyzed by bCD38 (cADPR represents only 1% of the reaction products). In the Michaelis complex, the substrate is bound in a constrained conformation; the enzyme uses this ground-state destabilization, in addition to a hydrophobic environment and desolvation of the nicotinamide-ribosyl bond, to destabilize the scissile bond leading to the formation of a ribooxocarbenium ion intermediate. The Glu218 side chain stabilizes this reaction intermediate and plays another important role during catalysis by polarizing the 2′-OH of the substrate NAD+. Based on our structural analysis and data on active site mutants, we propose a detailed analysis of the catalytic mechanism
Interpersonal psychotherapy (IPT) for late-life depression in general practice: uptake and satisfaction by patients, therapists and physicians
<p>Abstract</p> <p>Background</p> <p>Interpersonal Psychotherapy (IPT) is recommended in most depression treatment guidelines and proved to be a suitable treatment for elderly depressed patients. Despite the favorable results of IPT in research populations, the dissemination to general practice is surprisingly limited. Little is known about uptake and satisfaction when this therapy is introduced into real-life general practice.</p> <p>Methods</p> <p>Motivation and evaluation of patients, GPs and therapists were recorded and organizational barriers described alongside a randomized controlled trial. IPT, given by mental health workers, was compared with usual general practitioner (GP) care. Included were patients (≥55 years) who met the DSM-IV criteria for major depressive disorder.</p> <p>Results</p> <p>Patients were motivated for the psychotherapy intervention: of the 205 eligible patients, 143 (70%) entered the study, and of the 69 patients who were offered IPT, 77% complied with the treatment. IPT proved to be an attractive therapy for patients as well as for therapists from mental health organizations. General practitioners evaluated the intervention positively afterwards, mainly because of the time-limited and structured approach. Organizational barriers: no IPT therapists were available; an IPT trainer and supervisor had to be trained and training materials had to be developed and translated. Additionally, there was a lack of office space in some general practices; for therapists from private practices it was not feasible to participate because of financial reasons. IPT was superior to usual care in patients with moderate to severe depression.</p> <p>Conclusion</p> <p>As we succeeded in delivering IPT in primary care practice, and as IPT was superior to usual care, there are grounds to support the implementation of IPT for depressed elderly patients within general practice, as long as the practices have room for the therapists and financial barriers can be overcome. Consolidation may be achieved by making this intervention available through practice nurses or community psychiatric nurses who deliver IPT as part of a more comprehensive depression management program.</p
Are Apathy and Depressive Symptoms Related to Vascular White Matter Hyperintensities in Severe Late Life Depression?
OBJECTIVE:
Apathy symptoms are defined as a lack of interest and motivation. Patients with late-life depression (LLD) also suffer from lack of interest and motivation and previous studies have linked apathy to vascular white matter hyperintensities (WMH) of the brain in depressed and nondepressed patients. The aim of this study was to investigate the relationship between apathy symptoms, depressive symptoms, and WMH in LLD. We hypothesize that late-onset depression (LOD; first episode of depression after 55 years of age) is associated with WMH and apathy symptoms.
METHODS:
Apathy scores were collected for 87 inpatients diagnosed with LLD. Eighty patients underwent brain magnetic resonance imaging. Associations between depressive and apathy symptoms and WMH were analyzed using linear regression.
RESULTS:
All 3 subdomains of the 10-item Montgomery–Åsberg Depression Rating Scale correlated significantly with the apathy scale score (all P < .05). In the total sample, apathy nor depressive symptoms were related to specific WMH. In LOD only, periventricular WMH were associated with depression severity (β = 5.21, P = .04), while WMH in the left infratentorial region were associated with apathy symptoms (β coefficient = 5.89, P = .03).
CONCLUSION:
Apathy and depressive symptoms are highly overlapping in the current cohort of older patients with severe LLD, leading to the hypothesis that apathy symptoms are part of depressive symptoms in the symptom profile of older patients with severe LLD. Neither apathy nor depressive symptoms were related to WMH, suggesting that radiological markers of cerebrovascular disease, such as WMH, may not be useful in predicting these symptoms in severe LLD
Catastrophizing mediates the relationship between the personal belief in a just world and pain outcomes among chronic pain support group attendees
Health-related research suggests the belief in a just world can act as a personal resource that protects against the adverse effects of pain and illness. However, currently, little is known about how this belief, particularly in relation to one’s own life, might influence pain. Consistent with the suggestions of previous research, the present study undertook a secondary data analysis to investigate pain catastrophizing as a mediator of the relationship between the personal just world belief and chronic pain outcomes in a sample of chronic pain support group attendees. Partially supporting the hypotheses, catastrophizing was negatively correlated with the personal just world belief and mediated the relationship between this belief and pain and disability, but not distress. Suggestions for future research and intervention development are made
Collaborative Enhancement of Antibody Binding to Distinct PECAM-1 Epitopes Modulates Endothelial Targeting
Antibodies to platelet endothelial cell adhesion molecule-1 (PECAM-1) facilitate targeted drug delivery to endothelial cells by “vascular immunotargeting.” To define the targeting quantitatively, we investigated the endothelial binding of monoclonal antibodies (mAbs) to extracellular epitopes of PECAM-1. Surprisingly, we have found in human and mouse cell culture models that the endothelial binding of PECAM-directed mAbs and scFv therapeutic fusion protein is increased by co-administration of a paired mAb directed to an adjacent, yet distinct PECAM-1 epitope. This results in significant enhancement of functional activity of a PECAM-1-targeted scFv-thrombomodulin fusion protein generating therapeutic activated Protein C. The “collaborative enhancement” of mAb binding is affirmed in vivo, as manifested by enhanced pulmonary accumulation of intravenously administered radiolabeled PECAM-1 mAb when co-injected with an unlabeled paired mAb in mice. This is the first demonstration of a positive modulatory effect of endothelial binding and vascular immunotargeting provided by the simultaneous binding a paired mAb to adjacent distinct epitopes. The “collaborative enhancement” phenomenon provides a novel paradigm for optimizing the endothelial-targeted delivery of therapeutic agents
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