870 research outputs found
Limits to scale invariance in alluvial rivers
Assumptions about fluvial processes and processâform relations are made in general models and in many siteâspecific applications. Many standard assumptions about reachâscale flow resistance, bedâmaterial entrainment thresholds and transport rates, and downstream hydraulic geometry involve one or other of two types of scale invariance: a parameter (e.g. critical Shields number) has the same value in all rivers, or doubling one variable causes a fixed proportional change in another variable in all circumstances (e.g. powerâlaw hydraulic geometry). However, rivers vary greatly in size, gradient, and bed material, and many geomorphologists regard particular types of river as distinctive. This review examines the tension between universal scaling assumptions and perceived distinctions between different types of river. It identifies limits to scale invariance and departures from simple scaling, and illustrates them using large data sets spanning a wide range of conditions. Scaling considerations and data analysis support the commonly made distinction between coarseâbed and fineâbed reaches, whose different transport regimes can be traced to the different settlingâvelocity scalings for coarse and fine grains. They also help identify two endâmember subâtypes: steep shallow coarseâbed âtorrentsâ with distinctive flowâresistance scaling and increased entrainment threshold, and very large, lowâgradient âmega riversâ with predominantly suspended load, subdued secondary circulation, and extensive backwater conditions
How do you say âhelloâ? Personality impressions from brief novel voices
On hearing a novel voice, listeners readily form personality impressions of that speaker. Accurate or not, these impressions are known to affect subsequent interactions; yet the underlying psychological and acoustical bases remain poorly understood. Furthermore, hitherto studies have focussed on extended speech as opposed to analysing the instantaneous impressions we obtain from first experience. In this paper, through a mass online rating experiment, 320 participants rated 64 sub-second vocal utterances of the word âhelloâ on one of 10 personality traits. We show that: (1) personality judgements of brief utterances from unfamiliar speakers are consistent across listeners; (2) a two-dimensional âsocial voice spaceâ with axes mapping Valence (Trust, Likeability) and Dominance, each driven by differing combinations of vocal acoustics, adequately summarises ratings in both male and female voices; and (3) a positive combination of Valence and Dominance results in increased perceived male vocal Attractiveness, whereas perceived female vocal Attractiveness is largely controlled by increasing Valence. Results are discussed in relation to the rapid evaluation of personality and, in turn, the intent of others, as being driven by survival mechanisms via approach or avoidance behaviours. These findings provide empirical bases for predicting personality impressions from acoustical analyses of short utterances and for generating desired personality impressions in artificial voices
Herbivory by a Phloem-Feeding Insect Inhibits Floral Volatile Production
There is extensive knowledge on the effects of insect herbivory on volatile emission from vegetative tissue, but little is known about its impact on floral volatiles. We show that herbivory by phloem-feeding aphids inhibits floral volatile emission in white mustard Sinapis alba measured by gas chromatographic analysis of headspace volatiles. The effect of the Brassica specialist aphid Lipaphis erysimi was stronger than the generalist aphid Myzus persicae and feeding by chewing larvae of the moth Plutella xylostella caused no reduction in floral volatile emission. Field observations showed no effect of L. erysimi-mediated floral volatile emission on the total number of flower visits by pollinators. Olfactory bioassays suggested that although two aphid natural enemies could detect aphid inhibition of floral volatiles, their olfactory orientation to infested plants was not disrupted. This is the first demonstration that phloem-feeding herbivory can affect floral volatile emission, and that the outcome of interaction between herbivory and floral chemistry may differ depending on the herbivore's feeding mode and degree of specialisation. The findings provide new insights into interactions between insect herbivores and plant chemistry
The DARS (Dopamine Augmented Rehabilitation in Stroke) trial: protocol for a randomised controlled trial of Co-careldopa treatment in addition to routine NHS occupational and physical therapy after stroke
Background: Stroke has a huge impact, leaving more than a third of affected people with lasting disability and rehabilitation remains a cornerstone treatment in the National Health Service (NHS). Recovery of mobility and arm function post-stroke occurs through re-learning to use the affected body parts and/or learning to compensate with the lesser affected side. Promising evidence suggests that the addition of Co-careldopa to physical therapy and occupational therapy may improve the recovery of arm and leg movement and lead to improved function. Methods/design: Dopamine Augmented Rehabilitation in Stroke (DARS) is a multi-centre double-blind, randomised, placebo, controlled clinical trial of Co-careldopa in addition to routine NHS occupational therapy and physical therapy as part of early stroke rehabilitation. Participants will be randomised on a 1:1 basis to either Co-careldopa or placebo. The primary objective of the trial is to determine whether the addition of six weeks of Co-careldopa treatment to rehabilitation therapy can improve the proportion of patients who can walk independently eight weeks post-randomisation.
Discussion: The DARS trial will provide evidence as to whether Co-careldopa, in addition to routine NHS occupational and physical therapy, leads to a greater recovery of motor function, a reduction in carer dependency and advance rehabilitation treatments for people with stroke.
Trial registration: ISRCTN99643613 assigned on 4 December 2009
Apoptosis Inducing Effect of Plumbagin on Colonic Cancer Cells Depends on Expression of COX-2
Plumbagin, a quinonoid found in the plants of the Plumbaginaceae, possesses
medicinal properties. In this study we investigated the anti-proliferative and
apoptotic activity of plumbagin by using two human colonic cancer cell lines,
HT29 and HCT15. IC50 of Plumbagin for HCT15 and HT29 cells (22.5 ”M and
62.5 ”M, respectively) were significantly different. To study the response
of cancer cells during treatment strategies, cells were treated with two
different concentrations, 15 ”M, 30 ”M for HCT15 and 50 ”M, 75
”M for HT29 cells. Though activation of NFÎșB, Caspases-3, elevated
levels of TNF-α, cytosolic Cytochrome C were seen in both
HCT15 cells HT29 treated with plumbagin, aberrant apoptosis with decreased level
of pEGFR, pAkt, pGsk-3ÎČ, PCNA and Cyclin D1was observed only in 15 ”M
and 30 ”M plumbagin treated HCT15 and 75 ”M plumbagin treated HT29
cells. This suggests that plumbagin induces apoptosis in both HCT15 cells and
HT29 treated, whereas, proliferation was inhibited only in 15 ”M and 30
”M plumbagin treated HCT15 and 75 ”M plumbagin treated HT29 cells,
but not in 50 ”M plumbagin treated HT29 cells. Expression of COX-2 was
decreased in 75 ”M plumbagin treated HT29 cells when compared to 50
”M plumbagin treated HT29 cells, whereas HCT15 cells lack COX. Hence the
observed resistance to induction of apoptosis in 50 ”M plumbagin treated
HT29 cells are attributed to the expression of COX-2. In conclusion, plumbagin
induces apoptosis in colonic cancer cells through TNF-α mediated pathway
depending on expression of COX-2 expression
Despotism and Risk of Infanticide Influence Grizzly Bear Den-Site Selection
Given documented social dominance and intraspecific predation in bear populations, the ideal despotic distribution model and sex hypothesis of sexual segregation predict adult female grizzly bears (Ursus arctos) will avoid areas occupied by adult males to reduce risk of infanticide. Under ideal despotic distribution, juveniles should similarly avoid adult males to reduce predation risk. Den-site selection and use is an important component of grizzly bear ecology and may be influenced by multiple factors, including risk from conspecifics. To test the role of predation risk and the sex hypothesis of sexual segregation, we compared adult female (nâ=â142), adult male (nâ=â36), and juvenile (nâ=â35) den locations in Denali National Park and Preserve, Alaska, USA. We measured elevation, aspect, slope, and dominant land cover for each den site, and used maximum entropy modeling to determine which variables best predicted den sites. We identified the global model as the best-fitting model for adult female (area under curve (AUC)â=â0.926) and elevation as the best predictive variable for adult male (AUCâ=â0.880) den sites. The model containing land cover and elevation best-predicted juvenile (AUCâ=â0.841) den sites. Adult females spatially segregated from adult males, with dens characterized by higher elevations (â=â1,412 m, SEâ=â52) and steeper slopes (â=â21.9°, SEâ=â1.1) than adult male (elevation: â=â1,209 m, SEâ=â76; slope: â=â15.6°, SEâ=â1.9) den sites. Juveniles used a broad range of landscape attributes but did not avoid adult male denning areas. Observed spatial segregation by adult females supports the sex hypothesis of sexual segregation and we suggest is a mechanism to reduce risk of infanticide. Den site selection of adult males is likely related to distribution of food resources during spring
Position Paper on Olfactory Dysfunction
Background: Olfactory dysfunction is an increasingly recognised condition, associated with reduced quality of life and major health outcomes such as neurodegeneration and death. However, translational research in this field is limited by heterogeneity in methodological approach, including definitions of impairment, improvement and appropriate assessment techniques. Accordingly, effective treatments are limited. In an effort to encourage high quality and comparable work in this field, among others, we propose the following ideas and recommendations. Whilst full recommendations are outlined in the main document, key points include: -Patients with suspected olfactory loss should undergo a full examination of the head and neck, including rigid nasal endoscopy. -Subjective olfactory assessment should not be undertaken in isolation, given its poor reliability. -Psychophysical assessment tools used in clinical and research settings should include reliable and validated tests of odour threshold, and/or one of odour identification or discrimination. -Comprehensive chemosensory assessment should include gustatory screening. -Smell training can be helpful in patients with olfactory loss of several aetiologies. Conclusions: We hope the current manuscript will encourage clinicians and researchers to adopt a common language, and in so doing, increase the methodological quality, consistency and generalisability of work in this field
Multiple Routes and Milestones in the Folding of HIVâ1 Protease Monomer
Proteins fold on a time scale incompatible with a mechanism of random search in conformational space thus indicating that somehow they are guided to the native state through a funneled energetic landscape. At the same time the heterogeneous kinetics suggests the existence of several different folding routes. Here we propose a scenario for the folding mechanism of the monomer of HIVâ1 protease in which multiple pathways and milestone events coexist. A variety of computational approaches supports this picture. These include very long all-atom molecular dynamics simulations in explicit solvent, an analysis of the network of clusters found in multiple high-temperature unfolding simulations and a complete characterization of free-energy surfaces carried out using a structure-based potential at atomistic resolution and a combination of metadynamics and parallel tempering. Our results confirm that the monomer in solution is stable toward unfolding and show that at least two unfolding pathways exist. In our scenario, the formation of a hydrophobic core is a milestone in the folding process which must occur along all the routes that lead this protein towards its native state. Furthermore, the ensemble of folding pathways proposed here substantiates a rational drug design strategy based on inhibiting the folding of HIVâ1 protease
Efficacy and tolerability of gemtuzumab ozogamicin (anti-CD33 monoclonal antibody, CMA-676, Mylotarg(Âź)) in children with relapsed/refractory myeloid leukemia
BACKGROUND: Gemtuzumab ozogamicin (GO) is a cytotoxic anti-CD33 monoclonal antibody that has given promising preliminary results in adult myeloid CD33+ AML. We conducted a retrospective multicenter study of 12 children treated with GO on a compassionate basis (median age 5.5 y). Three patients (2 MDS/AML, 1 JMML) were refractory to first-line treatment, 8 patients with de novo AML were in refractory first relapse, and one patient with de novo AML was in 2(nd )relapse after stem cell transplantation (SCT). CD33 expression exceeded 20% in all cases. METHODS: GO was administered alone, at a unit dose of 3â9 mg/m(2), once (3 patients), twice (3 patients), three (5 patients) or five times (1 patient). Mean follow-up was 128 days (8â585 d). RESULTS: There were three complete responses (25%) leading to further curative treatment (SCT). Treatment failed in the other nine patients, and only one patient was alive at the end of follow-up. NCI-CTC grade III/IV adverse events comprised hematological toxicity (n = 12), hypertransaminasemia (n = 2), allergy and hyperbilirubinemia (1 case each). There was only one major adverse event (grade IV allergy). No case of sinusoidal obstruction syndrome occurred. CONCLUSION: These results warrant a prospective trial of GO in a larger population of children with AML
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