6,627 research outputs found
The Effect of Pollen on Coral Health
Corals are facing a range of threats, including rises in sea surface temperature and ocean acidification. Some now argue that keeping corals ex situ (in aquaria), may be not only important but necessary to prevent local extinction, for example in the Florida Reef Tract. Such collections or are already becoming common place, especially in the Caribbean, and may act as an ark, preserving and growing rare or endangered species in years to come. However, corals housed in aquaria face their own unique set of threats. For example, hobbyists (who have housed corals for decades) have noticed seasonal mortality is commonplace, incidentally following months of peak pollen production. So, could corals suffer from hay fever? If so, what does the future hold? In short, the answer to the first question is simple, and it is no, corals cannot suffer from hay fever, primarily because corals lack an adaptive immune system, which is necessary for the diagnosis of such an allergy. However, the threat from pollen could still be real. In this review, we explore how such seasonal mortality could play out. We explore increases in reactive oxygen species, the role of additional nutrients and how the microbiome of the pollen may introduce disease or cause dysbiosis in the holobiont
The neural correlates of emotion regulation by implementation intentions
Several studies have investigated the neural basis of effortful emotion regulation (ER) but the neural basis of automatic ER has been less comprehensively explored. The present study investigated the neural basis of automatic ER supported by âimplementation intentionsâ. 40 healthy participants underwent fMRI while viewing emotion-eliciting images and used either a previously-taught effortful ER strategy, in the form of a goal intention (e.g., try to take a detached perspective), or a more automatic ER strategy, in the form of an implementation intention (e.g., âIf I see something disgusting, then I will think these are just pixels on the screen!â), to regulate their emotional response. Whereas goal intention ER strategies were associated with activation of brain areas previously reported to be involved in effortful ER (including dorsolateral prefrontal cortex), ER strategies based on an implementation intention strategy were associated with activation of right inferior frontal gyrus and ventro-parietal cortex, which may reflect the attentional control processes automatically captured by the cue for action contained within the implementation intention. Goal intentions were also associated with less effective modulation of left amygdala, supporting the increased efficacy of ER under implementation intention instructions, which showed coupling of orbitofrontal cortex and amygdala. The findings support previous behavioural studies in suggesting that forming an implementation intention enables people to enact goal-directed responses with less effort and more efficiency
Onset of fluidization in vertically shaken granular material
When granular material is shaken vertically one observes convection, surface
fluidization, spontaneous heap formation and other effects. There is a
controversial discussion in literature whether there exists a threshold for the
Froude number below which these effects cannot be
observed anymore. By means of theoretical analysis and computer simulation we
find that there is no such single threshold. Instead we propose a modified
criterion which coincides with critical Froude number for small
driving frequency .Comment: 7 pages, 5 figure
Searching for the Slater Transition in the Pyrochlore CdOsO with Infrared Spectroscopy
Infrared reflectance measurements were made on the single crystal pyrochlore
CdOsO in order to examine the transformations of the
electronic structure and crystal lattice across the boundary of the metal
insulator transition at . All predicted IR active phonons are
observed in the conductivity over all temperatures and the oscillator strength
is found to be temperature independent. These results indicate that charge
ordering plays only a minor role in the MIT and that the transition is strictly
electronic in nature. The conductivity shows the clear opening of a gap with
. The gap opens continuously, with a temperature
dependence similar to that of BCS superconductors, and the gap edge having a
distinct dependence. All of these
observables support the suggestion of a Slater transition in CdOsO.Comment: 4 pages, 4 figure
Different doses of supplemental vitamin D maintain interleukin-5 without altering skeletal muscle strength: a randomized, double-blind, placebo-controlled study in vitamin D sufficient adults
<p>Abstract</p> <p>Background</p> <p>Supplemental vitamin D modulates inflammatory cytokines and skeletal muscle function, but results are inconsistent. It is unknown if these inconsistencies are dependent on the supplemental dose of vitamin D. Therefore, the purpose of this study was to identify the influence of different doses of supplemental vitamin D on inflammatory cytokines and muscular strength in young adults.</p> <p>Methods</p> <p>Men (<it>n </it>= 15) and women (<it>n </it>= 15) received a daily placebo or vitamin D supplement (200 or 4000 IU) for 28-d during the winter. Serum 25-hydroxyvitamin D (25(OH)D), cytokine concentrations and muscular (leg) strength measurements were performed prior to and during supplementation. Statistical significance of data were assessed with a two-way (time, treatment) analysis of variance (ANOVA) with repeated measures, followed by a Tukey's Honestly Significant Difference to test multiple pairwise comparisons.</p> <p>Results</p> <p>Upon enrollment, 63% of the subjects were vitamin D sufficient (serum 25(OH)D â„ 30 ng/ml). Serum 25(OH)D and interleukin (IL)-5 decreased (<it>P </it>< 0.05) across time in the placebo group. Supplemental vitamin D at 200 IU maintained serum 25(OH)D concentrations and increased IL-5 (<it>P </it>< 0.05). Supplemental vitamin D at 4000 IU increased (<it>P </it>< 0.05) serum 25(OH)D without altering IL-5 concentrations. Although serum 25(OH)D concentrations correlated (<it>P </it>< 0.05) with muscle strength, muscle strength was not changed by supplemental vitamin D.</p> <p>Conclusion</p> <p>In young adults who were vitamin D sufficient prior to supplementation, we conclude that a low-daily dose of supplemental vitamin D prevents serum 25(OH)D and IL-5 concentration decreases, and that muscular strength does not parallel the 25(OH)D increase induced by a high-daily dose of supplemental vitamin D. Considering that IL-5 protects against viruses and bacterial infections, these findings could have a broad physiological importance regarding the ability of vitamin D sufficiency to mediate the immune systems protection against infection.</p
Neuroendocrine abnormalities in Parkinson's disease.
Neuroendocrine abnormalities are common in Parkinson's disease (PD) and include disruption of melatonin secretion, disturbances of glucose, insulin resistance and bone metabolism, and body weight changes. They have been associated with multiple non-motor symptoms in PD and have important clinical consequences, including therapeutics. Some of the underlying mechanisms have been implicated in the pathogenesis of PD and represent promising targets for the development of disease biomarkers and neuroprotective therapies. In this systems-based review, we describe clinically relevant neuroendocrine abnormalities in Parkinson's disease to highlight their role in overall phenotype. We discuss pathophysiological mechanisms, clinical implications, and pharmacological and non-pharmacological interventions based on the current evidence. We also review recent advances in the field, focusing on the potential targets for development of neuroprotective drugs in Parkinson's disease and suggest future areas for research
Clinical prevalence of Lewy body dementia.
BACKGROUND: The prevalence of dementia with Lewy bodies (DLB) and dementia in Parkinson's disease (PDD) in routine clinical practice is unclear. Prevalence rates observed in clinical and population-based cohorts and neuropathological studies vary greatly. Small sample sizes and methodological factors in these studies limit generalisability to clinical practice. METHODS: We investigated prevalence in a case series across nine secondary care services over an 18-month period, to determine how commonly DLB and PDD cases are diagnosed and reviewed within two regions of the UK. RESULTS: Patients with DLB comprised 4.6% (95% CI 4.0-5.2%) of all dementia cases. DLB was represented in a significantly higher proportion of dementia cases in services in the North East (5.6%) than those in East Anglia (3.3%; Ï2 = 13.6, p < 0.01). DLB prevalence in individual services ranged from 2.4 to 5.9%. PDD comprised 9.7% (95% CI 8.3-11.1%) of Parkinson's disease cases. No significant variation in PDD prevalence was observed between regions or between services. CONCLUSIONS: We found that the frequency of clinical diagnosis of DLB varied between geographical regions in the UK, and that the prevalence of both DLB and PDD was much lower than would be expected in this case series, suggesting considerable under-diagnosis of both disorders. The significant variation in DLB diagnostic rates between these two regions may reflect true differences in disease prevalence, but more likely differences in diagnostic practice. The systematic introduction of more standardised diagnostic practice could improve the rates of diagnosis of both conditions
DNA-bridging by an archaeal histone variant via a unique tetramerisation interface
In eukaryotes, histone paralogues form obligate heterodimers such as H3/H4 and H2A/H2B that assemble into octameric nucleosome particles. Archaeal histones are dimeric and assemble on DNA into 'hypernucleosome' particles of varying sizes with each dimer wrapping 30âbp of DNA. These are composed of canonical and variant histone paralogues, but the function of these variants is poorly understood. Here, we characterise the structure and function of the histone paralogue MJ1647 from Methanocaldococcus jannaschii that has a unique C-terminal extension enabling homotetramerisation. The 1.9âĂ
X-ray structure of a dimeric MJ1647 species, structural modelling of the tetramer, and site-directed mutagenesis reveal that the C-terminal tetramerization module consists of two alpha helices in a handshake arrangement. Unlike canonical histones, MJ1647 tetramers can bridge two DNA molecules in vitro. Using single-molecule tethered particle motion and DNA binding assays, we show that MJ1647 tetramers bind ~60âbp DNA and compact DNA in a highly cooperative manner. We furthermore show that MJ1647 effectively competes with the transcription machinery to block access to the promoter in vitro. To the best of our knowledge, MJ1647 is the first histone shown to have DNA bridging properties, which has important implications for genome structure and gene expression in archaea
Growth and mass wasting of volcanic centers in the northern South Sandwich arc, South Atlantic, revealed by new multibeam mapping
New multibeam (swath) bathymetric sonar data acquired using an EM120 system on the RRS James Clark Ross, supplemented by sub-bottom profiling, reveals the underwater morphology of a not, vert, similar 12,000 km2 area in the northern part of the mainly submarine South Sandwich volcanic arc. The new data extend between 55° 45âČS and 57° 20âČS and include Protector Shoal and the areas around Zavodovski, Visokoi and the Candlemas islands groups. Each of these areas is a discrete volcanic center. The entirely submarine Protector Shoal area, close to the northern limit of the arc, forms a 55 km long eastâwest-trending seamount chain that is at least partly of silicic composition. The seamounts are comparable to small subaerial stratovolcanoes in size, with volumes up to 83 km3, indicating that they are the product of multiple eruptions over extended periods. Zavodovski, Visokoi and the Candlemas island group are the summits of three 3â3.5 km high volcanic edifices. The bathymetric data show evidence for relationships between constructional volcanic features, including migrating volcanic centers, structurally controlled constructional ridges, satellite lava flows and domes, and mass wasting of the edifices. Mass wasting takes place mainly by strong erosion at sea level, and dispersal of this material along chutes, probably as turbidity currents and other mass flows that deposit in extensive sediment wave fields. Large scale mass wasting structures include movement of unconsolidated debris in slides, slumps and debris avalanches. Volcanism is migrating westward relative to the underlying plate and major volcanoes are asymmetrical, being steep with abundant recent volcanism on their western flanks, and gently sloping with extinct, eroded volcanic sequences to their east. This is consistent with the calculated rate of subduction erosion of the fore-arc
Bayesian analysis of weak gravitational lensing and Sunyaev-Zel'dovich data for six galaxy clusters
We present an analysis of observations made with the Arcminute Microkelvin
Imager (AMI) and the Canada-France-Hawaii Telescope (CFHT) of six galaxy
clusters in a redshift range of 0.16--0.41. The cluster gas is modelled using
the Sunyaev--Zel'dovich (SZ) data provided by AMI, while the total mass is
modelled using the lensing data from the CFHT. In this paper, we: i) find very
good agreement between SZ measurements (assuming large-scale virialisation and
a gas-fraction prior) and lensing measurements of the total cluster masses out
to r_200; ii) perform the first multiple-component weak-lensing analysis of
A115; iii) confirm the unusual separation between the gas and mass components
in A1914; iv) jointly analyse the SZ and lensing data for the relaxed cluster
A611, confirming our use of a simulation-derived mass-temperature relation for
parameterizing measurements of the SZ effect.Comment: 22 pages, 12 figures, 12 tables, published by MNRA
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