Fluctuation Induced Instabilities in Front Propagation up a Co-Moving Reaction Gradient in Two Dimensions

We study 2D fronts propagating up a co-moving reaction rate gradient in finite number reaction-diffusion systems. We show that in a 2D rectangular channel, planar solutions to the deterministic mean-field equation are stable with respect to deviations from planarity. We argue that planar fronts in the corresponding stochastic system, on the other hand, are unstable if the channel width exceeds a critical value. Furthermore, the velocity of the stochastic fronts is shown to depend on the channel width in a simple and interesting way, in contrast to fronts in the deterministic MFE. Thus, fluctuations alter the behavior of these fronts in an essential way. These affects are shown to be partially captured by introducing a density cutoff in the reaction rate. Some of the predictions of the cutoff mean-field approach are shown to be in quantitative accord with the stochastic results

An empirical approach to modeling ion production rates in Titan's ionosphere II: Ion production rates on the nightside

Ionization of neutrals by precipitating electrons and ions is the main source of Titan's nightside ionosphere. This paper has two goals: (1) characterization of the role of electron impact ionization on the nightside ionosphere for different magnetospheric conditions and (2) presentation of empirical ion production rates determined using densities measured by the Cassini Ion and Neutral Mass Spectrometer on the nightside. The ionosphere between 1000 and 1400 km is emphasized. We adopt electron fluxes measured by the Cassini Plasma Spectrometer-Electron Spectrometer and the Magnetospheric Imaging Instrument as classified by Rymer et al. (2009). The current paper follows an earlier paper (Paper I), in which we investigated sources of Titan's dayside ionosphere and demonstrated that the photoionization process is well understood. The current paper (Paper II) demonstrates that modeled and empirical ionization rates on the nightside are in agreement with an electron precipitation source above 1100 km. Ion production rate profiles appropriate for different Saturnian magnetospheric conditions, as outlined by Rymer et al., are constructed for various magnetic field topologies. Empirical production rate profiles are generated for deep nightside flybys of Titan. The results also suggest that at lower altitudes (below 1100 km) another source, such as ion precipitation, is probably needed

Deep Brain Stimulation of the Subthalamic Nucleus Improves Reward-Based Decision-Learning in Parkinson's Disease

Recently, the subthalamic nucleus (STN) has been shown to be critically involved in decision-making, action selection, and motor control. Here we investigate the effect of deep brain stimulation (DBS) of the STN on reward-based decision-learning in patients diagnosed with Parkinson's disease (PD). We determined computational measures of outcome evaluation and reward prediction from PD patients who performed a probabilistic reward-based decision-learning task. In previous work, these measures covaried with activation in the nucleus caudatus (outcome evaluation during the early phases of learning) and the putamen (reward prediction during later phases of learning). We observed that stimulation of the STN motor regions in PD patients served to improve reward-based decision-learning, probably through its effect on activity in frontostriatal motor loops (prominently involving the putamen and, hence, reward prediction). In a subset of relatively younger patients with relatively shorter disease duration, the effects of DBS appeared to spread to more cognitive regions of the STN, benefiting loops that connect the caudate to various prefrontal areas importantfor outcome evaluation. These results highlight positive effects of STN stimulation on cognitive functions that may benefit PD patients in daily-life association-learning situations

Exposing an “Intangible” Cognitive Skill Among Collegiate Football Players: II. Enhanced Response Impulse Control

American football is played in a dynamic environment that places considerable demands on a player’s ability to make fast, precise reactions while controlling premature, impulsive reactions to spatial misinformation. We investigated the hypothesis that collegiate football players are more proficient than their non-athlete counterparts at controlling impulsive motor actions. National Collegiate Athletic Association (NCAA) Division I football players (n = 280) and non-athlete controls (n = 32) completed a variant of the Simon conflict task, which quantifies choice reaction speed and the proficiency of controlling spatially driven response impulses. Overall, the choice reaction times (RTs) and accuracy rates of football players and controls were equivalent. Similarly, football players and controls were equally susceptible to producing incorrect impulsive motor responses. However, the slowing of RT attributed to the activation and successful inhibition of these impulses (i.e., the Simon effect) was reduced significantly among football players compared to controls. Moreover, differences in impulse control varied by position among the players, with the reduction being greater for offensive than for defensive players. Among offensive players, running backs, wide receivers, and offensive linemen had greater impulse control than did controls, whereas among defensive players only linebackers had greater control. Notably, the Simon effect was reduced by 60% in running backs compared to controls. These results contribute to emerging evidence that elite football players possess more proficient executive control over their motor systems than their age counterparts and suggest that the speed of controlling impulsive motor reactions may represent an enhanced cognitive “intangible” among football players

General Practitioners involvement in enteral tube feeding at home: a qualitative study

<p>Abstract</p> <p>Background</p> <p>Complex medical treatment is moving from hospital to primary care and General Practitioners (GPs) are increasingly asked to undertake new roles. There are now an estimated 19,500 patients being fed in the UK in the community on enteral tube feeding using a variety of different feeding tubes (Percutaneous endoscopic gastrostomy (PEG), Jejunostomy, or nasogastric (NG). The majority of patients are over the age of 65 years when they had artificial feeding initiated and mainly because of dysphagia. The aim of this study was to explore GPs knowledge, attitudes and skills relating to enteral feeding in the community.</p> <p>Methods</p> <p>Semi-structured one-to-one interviews with a convenience sample of GPs in Northern Ireland.</p> <p>Results</p> <p>Twenty-three GPs in three health boards in Northern Ireland participated in the study. Most found dealing with enteral feeding to be a predominantly negative experience. They had little involvement in patient selection for the procedure and poor or no discharge information. GPs felt inadequately trained, there was poor communication between primary and secondary care and little support. There was anger and frustration among GPs about lack of resources (funding and training), and the perception that primary care was used as a dumping ground.</p> <p>Conclusion</p> <p>Moving complex medical treatment from secondary to primary care has major implications for GPs who should be included in the patient selection process, have adequate discharge information about their patients, be adequately resourced and have appropriate support and training.</p

Understanding how education/support groups help lone mothers

<p>Abstract</p> <p>Background</p> <p>Lone-mother led families are at increased risk of psychosocial disadvantage, social isolation and mental health morbidity. Community-based programs are more accessible for families seeking assistance. We examine the experiences of eight lone mothers participating in a larger randomized controlled trial (RCT) of a community-based education/support group program using mixed methods.</p> <p>Methods</p> <p>A purposeful sample of eight mothers participating in the intervention arm of an RCT of community-based support/education groups was selected for the qualitative study. Individual interviews asked mothers about themselves and their relationships with their children before and after the group. Interviews were taped, transcribed and content analysis was used to code and interpret the data. Quantitative data collected in the RCT were used to describe these mothers.</p> <p>Results</p> <p>Mothers participating in the RCT and qualitative study experienced multiple difficulties, including financial and mood problems. These mothers reported that before participating in the group, they had shared experiences of social isolation, stigma, a sense of failure, poor relationships with their children and difficulties with financial management. After the group, mothers identified improved self-esteem, support from other mothers, improved parenting skills and improved communication with their children as outcomes of group participation.</p> <p>Conclusions</p> <p>The qualitative data revealed mothers' perceptions of specific areas that improved by participating in the group. The utility of complementary information provided by qualitative and quantitative methods in understanding program impact, as well as the need for broader assistance is noted.</p

Regulation of Classical Cadherin Membrane Expression and F-Actin Assembly by Alpha-Catenins, during Xenopus Embryogenesis

Alpha (α)-E-catenin is a component of the cadherin complex, and has long been thought to provide a link between cell surface cadherins and the actin skeleton. More recently, it has also been implicated in mechano-sensing, and in the control of tissue size. Here we use the early Xenopus embryos to explore functional differences between two α-catenin family members, α-E- and α-N-catenin, and their interactions with the different classical cadherins that appear as tissues of the embryo become segregated from each other. We show that they play both cadherin-specific and context-specific roles in the emerging tissues of the embryo. α-E-catenin interacts with both C- and E-cadherin. It is specifically required for junctional localization of C-cadherin, but not of E-cadherin or N-cadherin at the neurula stage. α-N-cadherin interacts only with, and is specifically required for junctional localization of, N-cadherin. In addition, α -E-catenin is essential for normal tissue size control in the non-neural ectoderm, but not in the neural ectoderm or the blastula. We also show context specificity in cadherin/ α-catenin interactions. E-cadherin requires α-E-catenin for junctional localization in some tissues, but not in others, during early development. These specific functional cadherin/alpha-catenin interactions may explain the basis of cadherin specificity of actin assembly and morphogenetic movements seen previously in the neural and non-neural ectoderm

Diagnostic accuracy for the extent and activity of newly diagnosed and relapsed Crohn’s disease: a multicentre prospective comparison of magnetic resonance enterography and small bowel ultrasound –The METRIC Trial

Background Magnetic resonance enterography (MRE) and ultrasound (US) are used to image Crohn’s disease, but comparative accuracy for disease extent and activity is not known with certainty. We undertook a prospective multicentre cohort trial to address this Methods We recruited from 8 UK hospitals. Eligible patients were 16 years or older, newly diagnosed with Crohn’s disease, or had established disease with suspected relapse. Consecutive patients underwent MRE and US in addition to standard investigations. Discrepancy between MRE and US for small bowel (SB) disease presence triggered an additional investigation, if not already available. The primary outcome was difference in per patient sensitivity for SB disease extent (correct identification and segmental localisation) against a construct reference standard (panel diagnosis). Accuracy for SB and colonic disease presence and activity were secondary outcomes. The trial is completed (ISRCTN03982913). Findings 284 patients completed the trial (133 new diagnosis, 151 relapse). MRE sensitivity (n=233) for SB disease extent (80% [95%CI 72 to 86]) and presence (97% [91 to 99]) were significantly greater than US (70% [62 to 78], 92% [84 to 96]); a 10% (1 to 18; p=0.027), and 5% (1 to 9), difference respectively. MRE specificity for SB disease extent (95% [85 to 98]) was significantly greater than US (81% [64 to 91]). Sensitivity for active SB disease was significantly greater for MRE than US (96% [92 to 99] vs. 90% [82 to 95]), difference 6% (2 to 11). Overall, there were no significant accuracy differences for colonic disease presence. Accuracy in newly diagnosed and relapse patients was similar, although US had significantly greater sensitivity for colonic disease than MRE in newly diagnosed patients (67% [49 to 81) vs. 47% [31 to 64]), difference 20% (1 to 39). There were no serious adverse events. Interpretation MRE has higher diagnostic accuracy for the extent and activity of SB Crohn’s disease than US when tested in a prospective multi centre cohort trial setting

Diagnostic accuracy of magnetic resonance enterography and small bowel ultrasound for the extent and activity of newly diagnosed and relapsed Crohn's disease (METRIC): a multicentre trial

Magnetic resonance enterography (MRE) and ultrasound are used to image Crohn's disease, but their comparative accuracy for assessing disease extent and activity is not known with certainty. Therefore, we did a multicentre trial to address this issue. We recruited patients from eight UK hospitals. Eligible patients were 16 years or older, with newly diagnosed Crohn's disease or with established disease and suspected relapse. Consecutive patients had MRE and ultrasound in addition to standard investigations. Discrepancy between MRE and ultrasound for the presence of small bowel disease triggered an additional investigation, if not already available. The primary outcome was difference in per-patient sensitivity for small bowel disease extent (correct identification and segmental localisation) against a construct reference standard (panel diagnosis). This trial is registered with the International Standard Randomised Controlled Trial, number ISRCTN03982913, and has been completed. 284 patients completed the trial (133 in the newly diagnosed group, 151 in the relapse group). Based on the reference standard, 233 (82%) patients had small bowel Crohn's disease. The sensitivity of MRE for small bowel disease extent (80% [95% CI 72-86]) and presence (97% [91-99]) were significantly greater than that of ultrasound (70% [62-78] for disease extent, 92% [84-96] for disease presence); a 10% (95% CI 1-18; p=0·027) difference for extent, and 5% (1-9; p=0·025) difference for presence. The specificity of MRE for small bowel disease extent (95% [85-98]) was significantly greater than that of ultrasound (81% [64-91]); a difference of 14% (1-27; p=0·039). The specificity for small bowel disease presence was 96% (95% CI 86-99) with MRE and 84% (65-94) with ultrasound (difference 12% [0-25]; p=0·054). There were no serious adverse events. Both MRE and ultrasound have high sensitivity for detecting small bowel disease presence and both are valid first-line investigations, and viable alternatives to ileocolonoscopy. However, in a national health service setting, MRE is generally the preferred radiological investigation when available because its sensitivity and specificity exceed ultrasound significantly. National Institute of Health and Research Health Technology Assessment. [Abstract copyright: Copyright © 2018 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.