Explaining the presence of perennial liquid water bodies in the firn of the Greenland Ice Sheet

pre-printRecent observations have shown that the firn layer on the Greenland Ice Sheet features subsurface bodies of liquid water at the end of the winter season. Using a model with basic firn hydrology, thermodynamics, and compaction in one dimension, we find that a combination of moderate to strong surface melt and a high annual accumulation rate is required to form such a perennial firn aquifer. The high accumulation rate ensures that there is pore space available to store water at a depth where it is protected from the winter cold. Low-accumulation sites cannot provide sufficiently deep pore space to store liquid water. However, for even higher accumulation rates, the total cold content of the winter accumulation becomes sufficient to refreeze the total amount of liquid water. As a consequence, wintertime or springtime observations of subsurface liquid water in these specific accumulation conditions cannot distinguish between a truly perennial firn aquifer and water layers that will ultimately refreeze completely

Программа автоматизированного расчёта параметров прокатки, в комплексе «приводная – неприводная клети»

Разработан алгоритм программы автоматизированного расчёта параметров процесса прокатки в комплексе ПК–НК и программа на языке С++, обеспечиваю- щая расчёт энергосиловых и технологических параметров прокатки в комплексе ПК–НК с учётом ограничивающих процесс факторов

Connectedness of healthcare professionals involved in the treatment of patients with Parkinson's disease: a social networks study

<p>Abstract</p> <p>Background</p> <p>Patients with chronic illness typically receive ambulatory treatment from multiple health professionals. Connectedness between these professionals may influence their clinical decisions and the coordination of patient care. We aimed to describe and analyze connectedness in a regional network of health professionals involved in ambulatory treatment of patients with Parkinson's disease (PD).</p> <p>Methods</p> <p>Observational study with 104 health professionals who had joined a newly established network (ParkinsonNet) were asked to complete a pre-structured form to report on their professional contacts with others in the network. Using social networks methods, network measures were calculated for the total network and for the networks of individual health professionals. We planned to test differences between subgroups of health professionals regarding 12 network measures, using a random permutation method.</p> <p>Results</p> <p>Ninety-six health professionals (92%) provided data on 101 professionals. The reciprocity of reported connections was 0.42 in the network of professional contacts. Measures characterizing the individual networks showed a wide variation; <it>e.g</it>., density varied between 0 and 100% (mean value 28.4%). Health professionals with ≥10 PD patients had higher values on 7 out of 12 network measures compare to those with < 10 PD patients (size, number of connections, two step reach, indegree centrality, outdegree centrality, inreach centrality, betweenness centrality). Primary care professionals had lower values on 11 out of 12 network measures (all but reach efficiency) compared to professionals who were affiliated with a hospital.</p> <p>Conclusions</p> <p>Our measure of professional connectedness proved to be feasible in a regional disease-specific network of health professionals. Network measures describing patterns in the professional contacts showed relevant variation across professionals. A higher caseload and an affiliation with a hospital were associated with stronger connectedness with other health professionals.</p

Improving Community Healthcare for Patients with Parkinson's Disease: The Dutch Model

Because of the complex nature of Parkinson's disease, a wide variety of health professionals are involved in care. Stepwise, we have addressed the challenges in the provision of multidisciplinary care for this patient group. As a starting point, we have gained detailed insight into the current delivery of allied healthcare, as well as the barriers and facilitators for optimal care. To overcome the identified barriers, a tertiary referral centre was founded; evidence-based guidelines were developed and cost-effectively implemented within regional community networks of specifically trained allied health professionals (the ParkinsonNet concept). We increasingly use ICT to bind these professional networks together and also to empower and engage patients in making decisions about their health. This comprehensive approach is likely to be feasible for other countries as well, so we currently collaborate in a European collaboration to improve community care for persons with Parkinson's disease

Preparatory Effects of Distractor Suppression: Evidence from Visual Cortex

Spatial selective attention is the mechanism that facilitates the selection of relevant information over irrelevant information in the visual field. The current study investigated whether foreknowledge of the presence or absence of distractors surrounding an impending target stimulus results in preparatory changes in visual cortex. We cued the location of the target and the presence or absence of distractors surrounding the target while changes in blood oxygen level dependent (BOLD) signals were measured. In line with prior work, we found that top-down spatial attention resulted in an increased contralateral BOLD response, evoked by the cue throughout early visual cortex (areas V1, V2 and V3). In addition, cues indicating distractor presence evoked a substantial increase in the magnitude of the BOLD signal in visual area V3, but not in V2 or V1. This study shows that prior knowledge concerning the presence of a distractor results in enhanced attentional modulation of visual cortex, in visual areas where neuronal receptive fields are large enough to encompass both targets and distractors. We interpret these findings as evidence that top-down attentional control processes include active preparatory suppression mechanisms for irrelevant, distracting information in the visual scene

Using Medical Claims Analyses to Understand Interventions for Parkinson Patients.

The scientific evidence to support the value of a range of non-pharmacological interventions for people with Parkinson's disease (PD) is increasing. However, showing unequivocally that specific interventions are better than usual care is not straightforward because of generic drawbacks of clinical trials. Here, we address these challenges, specifically related to the context of evaluating complex non-pharmacological interventions for people with PD. Moreover, we discuss the potential merits of undertaking "real world" analyses using medical claims data. We illustrate this approach by discussing an interesting recent publication in The Lancet Neurology, which used such an approach to demonstrate the value of specialized physiotherapy for PD patients, over and above usual care physiotherapy.Professor Bastiaan R. Bloem is supported by a research grant of the Parkinson’s Foundation. Dr. Nienke M. de Vries is supported by a research grant from The Netherlands Organization for Health Research and Development. Dr. Allison Willis is supported by the Parkinson’s Foundation, the National Institutes of Health (R01-NS-099129-01A1), the Patient Centred Outcomes Research Institute, and the University of Pennsylvania

The effects of combined glucosamine sulfate and chondroitin sulfate supplements on condylar cartilage remodeling during functional appliance therapy. A Micro-CT study.

Glucosamine and chondroitin sulphate supplementation is used to prevent the degeneration of articular surfaces and also to enhance repair and regeneration of cartilage. The ability for adaptation of condylar cartilage to mandibular forward positioning is what constitutes the fundamental rationale for orthodontic functional therapy, which partially contributes to the correction of jaw discrepancies in growing Skeletal II mandibular retrusive patients. The purpose of this study was to qualitatively and quantitatively analyse the effect of Glucosamine sulphate (GS) and Chondroitin sulphate (CS) supplementation on condylar remodeling with functional appliance therapy in rats. One hundred and forty 3-week-old female Sprague-Dawley rats were randomly divided into 4 groups consisting of; baseline controls, supplementation only, functional appliances only and those receiving both supplements and functional appliances. Supplements were preloaded for a period of 2 weeks prior to the placement of functional appliances at five weeks of age. The animals were sacrificed at days 0, 7 and 21 after appliance placement. The appliances were removed in the remaining experimental animals on day 21 with sacrifice on day 28 to analyse post growth modification changes. Condylar samples were then soaked in 0.2 M Gadolinium Chloride (GdCl3) (aq) for 6 days and analyzed using micro-computed tomography (μCT) for morphological characteristics and linear and volumetric measurements of the mandibular condyle. The results demonstrated supplement therapy increased the volume of cartilage with and without functional appliance therapy. Functional appliance therapy alone resulted in increases in cartilage volume over untreated animals, with peak volume increases occurring by day 7 of appliance wear followed with decreases as endochondral ossification ensued. Supplement therapy was found to enhance the normal biological response to functional appliance therapy in the rat model

Spatial Response of Greenland's Firn Layer to NAO Variability

Firn on the Greenland Ice Sheet (GrIS) buffers meltwater, and has a variable thickness, complicating observations of volume change to mass change. In this study, we use a firn model (IMAU-FDM v1.2G) forced by a regional climate model (RACMO2.3p2) to investigate how the GrIS firn layer thickness and pore space have evolved since 1958 in response to variability in the large-scale atmospheric circulation. On interannual timescales, the firn layer thickness and pore space show a spatially heterogeneous response to variability in the North Atlantic Oscillation (NAO). Notably, a stronger NAO following the record warm summer of 2012 led the firn layer in the south and east of the ice sheet to regain thickness and pore space after a period of thinning and reduced pore space. In the southwest, a decrease in melt dominated after 2012, whereas in the east, the main driver was an increase in snow accumulation. At the same time, the firn in the northwestern ice sheet continued to lose pore space. The NAO also varies on intra-annual timescales, being typically stronger in winter than in summer. This impacts the amplitude of the seasonal cycle in GrIS firn thickness and pore space. In the wet southeastern GrIS, most of the snow accumulates during the winter, when melting and densification are relatively weak, leading to a large seasonal cycle in thickness and pore space. The opposite occurs in other regions, where snowfall peaks in summer or autumn. This dampens the seasonal amplitude of firn thickness and pore space

Trends in Antarctic Peninsula surface melting conditions from observations and regional climate modeling

Multidecadal meteorological station records and microwave backscatter time-series from the SeaWinds scatterometer onboard QuikSCAT (QSCAT) were used to calculate temporal and spatial trends in surface melting conditions on the Antarctic Peninsula (AP). Four of six long-term station records showed strongly positive and statistically significant trends in duration of melting conditions, including a 95% increase in the average annual positive degree day sum (PDD) at Faraday/Vernadsky, since 1948. A validated, threshold-based melt detection method was employed to derive detailed melt season onset, extent, and duration climatologies on the AP from enhanced resolution QSCAT data during 1999–2009. Austral summer melt on the AP was linked to regional- and synoptic-scale atmospheric variability by respectively correlating melt season onset and extent with November near-surface air temperatures and the October–January averaged index of the Southern Hemisphere Annular Mode (SAM). The spatial pattern, magnitude, and interannual variability of AP melt from observations was closely reproduced by simulations of the regional model RACMO2. Local discrepancies between observations and model simulations were likely a result of the QSCAT response to, and RACMO2 treatment of, ponded surface water, and the relatively crude representation of coastal climate in the 27 km RACMO2 grid