The Burst Mode of Accretion in Primordial Star Formation

We present simulation results for the formation and long-term evolution of a primordial protostellar disk harbored by a first star. Using a 2+1D nonaxisymmetric thin disk numerical simulation, together with a barotropic relation for the gas, we are able to probe ~20 kyr of the disk's evolution. During this time period we observe fragmentation leading to loosely bound gaseous clumps within the disk. These are then torqued inward and accreted onto the growing protostar, giving rise to a burst phenomenon. The luminous feedback produced by this mechanism may have important consequences for the subsequent growth of the protostar.Comment: 3 pages, 2 figures, to appear in proceedings of First Stars IV meeting (Kyoto, Japan; 2012

A Case of the Red Pants Mondays: The Connection Between Fandom, Tumblr, and Consumption

Social media networks allow for the interaction of individuals from across the globe based on mutual social connections or shared interests. These networks are of particular benefit to the propagation of fandoms. The unique search capacity of Tumblr enables the identification of fellow fans, a forum in which to engage easily in shared fandom creation, commodity consumption, and activities such as cos-play and role-play. Fandom consumption can manifest in both material and aesthetic, or cultural, forms. This paper presents the fandom of the BBC\u27s series Sherlock as a case study of the connections between social media, fandom, and consumption. The series ran as two, three-episode seasons and is currently in the midst of a two year hiatus. Though content and commodity consumption existed from the inception of the series, the current production break has expanded the desire of fandom members to create their own series-inspired original content as well as material commodities, many of which come in the form of apparel, jewelry, or other wearable goods. Tumblr has provided the forum by which this fandom can fill the void created by said break and perpetuate its very existence. For the purpose of this paper, the investigator will first identify the question(s) to be asked, then discuss methodology, provide a theoretical and practical justification for further investigation, before discussing findings and conclusions

Non-invasive brain stimulation techniques for chronic pain (review)

Background This is an updated version of the original Cochrane review published in 2010, Issue 9. Non-invasive brain stimulation techniques aim to induce an electrical stimulation of the brain in an attempt to reduce chronic pain by directly altering brain activity. They include repetitive transcranial magnetic stimulation (rTMS), cranial electrotherapy stimulation (CES), transcranial direct current stimulation (tDCS) and reduced impedance non-invasive cortical electrostimulation (RINCE). Objectives To evaluate the efficacy of non-invasive brain stimulation techniques in chronic pain. Search methods We searched CENTRAL (2013, Issue 6), MEDLINE, EMBASE, CINAHL, PsycINFO, LILACS and clinical trials registers. The original search for the review was run in November 2009 and searched all databases from their inception. To identify studies for inclusion in this update we searched from 2009 to July 2013. Selection criteria Randomised and quasi-randomised studies of rTMS, CES, tDCS or RINCE if they employed a sham stimulation control group, recruited patients over the age of 18 with pain of three months duration or more and measured pain as a primary outcome. Data collection and analysis Two authors independently extracted and verified data. Where possible we entered data into meta-analyses. We excluded studies judged as being at high risk of bias from the analysis. We used the GRADE system to summarise the quality of evidence for core comparisons. Main results We included an additional 23 trials (involving 773 participants randomised) in this update, making a total of 56 trials in the review (involving 1710 participants randomised). This update included a total of 30 rTMS studies, 11 CES, 14 tDCS and one study of RINCE(the original review included 19 rTMS, eight CES and six tDCS studies). We judged only three studies as being at low risk of bias across all criteria. Meta-analysis of studies of rTMS (involving 528 participants) demonstrated significant heterogeneity. Pre-specified subgroup analyses suggest that low-frequency stimulation is ineffective (low-quality evidence) and that rTMS applied to the dorsolateral prefrontal cortex is ineffective (very low-quality evidence). We found a short-term effect on pain of active high-frequency stimulation of the motor cortex in single-dose studies (low-quality evidence, standardised mean difference (SMD) 0.39 (95% confidence interval (CI) -0.27 to -0.51 P \u3c 0.01)). This equates to a 12% (95% CI 8% to 15%) reduction in pain, which does not exceed the pre-established criteria for a minimal clinically important difference (≥ 15%). Evidence for multiple-dose studies was heterogenous but did not demonstrate a significant effect (very low-quality evidence). For CES (six studies, 270 participants) no statistically significant difference was found between active stimulation and sham (low-quality evidence). Analysis of tDCS studies (11 studies, 193 people) demonstrated significant heterogeneity and did not find a significant difference between active and sham stimulation (very low-quality evidence). Pre-specified subgroup analysis of tDCS applied to the motor cortex (n = 183) did not demonstrate a statistically significant effect and this lack of effect was consistent for subgroups of single or multiple-dose studies. One small study (n = 91) at unclear risk of bias suggested a positive effect of RINCE over sham stimulation on pain (very low-quality evidence). Non-invasive brain stimulation appears to be frequently associated with minor and transient side effects, though there were two reported incidences of seizure related to active rTMS in the included studies. Authors\u27 conclusions Single doses of high-frequency rTMS of the motor cortex may have small short-term effects on chronic pain. It is likely that multiple sources of bias may exaggerate this observed effect. The effects do not meet the predetermined threshold of minimal clinical significance and multiple-dose studies do not consistently demonstrate effectiveness. The available evidence suggests that low-frequency rTMS, rTMS applied to the pre-frontal cortex, CES and tDCS are not effective in the treatment of chronic pain. While the broad conclusions for rTMS and CES have not changed substantially, the addition of this new evidence and the application of the GRADE system has modified some of our interpretation and the conclusion regarding the effectiveness of tDCS has changed. We recommend that previous readers should re-read this update. There is a need for larger, rigorously designed studies, particularly of longer courses of stimulation. It is likely that future evidence may substantially impact upon the presented results

Non-invasive brain stimulation techniques for chronic pain (Review)

Background: This is an updated version of the original Cochrane Review published in 2010, Issue 9, and last updated in 2014, Issue 4. Non-invasive brain stimulation techniques aim to induce an electrical stimulation of the brain in an attempt to reduce chronic pain by directly altering brain activity. They include repetitive transcranial magnetic stimulation (rTMS), cranial electrotherapy stimulation (CES), transcranial direct current stimulation (tDCS), transcranial random noise stimulation (tRNS) and reduced impedance non-invasive cortical electrostimulation (RINCE). Objectives: To evaluate the efficacy of non-invasive cortical stimulation techniques in the treatment of chronic pain. Search methods: For this update we searched CENTRAL, MEDLINE, Embase, CINAHL, PsycINFO, LILACS and clinical trials registers from July 2013 to October 2017. Selection criteria: Randomised and quasi-randomised studies of rTMS, CES, tDCS, RINCE and tRNS if they employed a sham stimulation control group, recruited patients over the age of 18 years with pain of three months’ duration or more, and measured pain as an outcome. Outcomes of interest were pain intensity measured using visual analogue scales or numerical rating scales, disability, quality of life and adverse events. Data collection and analysis: Two review authors independently extracted and verified data. Where possible we entered data into meta-analyses, excluding studies judged as high risk of bias. We used the GRADE system to assess the quality of evidence for core comparisons, and created three ’Summary of findings’ tables. Main results: We included an additional 38 trials (involving 1225 randomised participants) in this update, making a total of 94 trials in the review (involving 2983 randomised participants). This update included a total of 42 rTMS studies, 11 CES, 36 tDCS, two RINCE and two tRNS. One study evaluated both rTMS and tDCS. We judged only four studies as low risk of bias across all key criteria. Using the GRADE criteria we judged the quality of evidence for each outcome, and for all comparisons as low or very low; in large part this was due to issues of blinding and of precision. rTMS: Meta-analysis of rTMS studies versus sham for pain intensity at short-term follow-up (0 to \u3c 1 week postintervention), (27 studies, involving 655 participants), demonstrated a small effect with heterogeneity (standardised mean difference (SMD) -0.22, 95% confidence interval (CI) -0.29 to -0.16, low-quality evidence). This equates to a 7% (95% CI 5% to 9%) reduction in pain, or a 0.40 (95% CI 0.53 to 0.32) point reduction on a 0 to 10 pain intensity scale, which does not meet the minimum clinically important difference threshold of 15% or greater. Pre-specified subgroup analyses did not find a difference between low-frequency stimulation (low-quality evidence) and rTMS applied to the prefrontal cortex compared to sham for reducing pain intensity at short-term follow-up (very low-quality evidence). High-frequency stimulation of the motor cortex in single-dose studies was associated with a small short-term reduction in pain intensity at short-term follow-up (low-quality evidence, pooled n = 249, SMD -0.38 95% CI -0.49 to -0.27). This equates to a 12% (95% CI 9% to 16%) reduction in pain, or a 0.77 (95% CI 0.55 to 0.99) point change on a 0 to 10 pain intensity scale, which does not achieve the minimum clinically important difference threshold of 15% or greater. The results from multiple-dose studies were heterogeneous and there was no evidence of an effect in this subgroup (very low-quality evidence). We did not find evidence that rTMS improved disability. Meta-analysis of studies of rTMS versus sham for quality of life (measured using the Fibromyalgia Impact Questionnaire (FIQ) at short-term follow-up demonstrated a positive effect (MD -10.80 95% CI -15.04 to -6.55, low-quality evidence). CES: For CES (five studies, 270 participants) we found no evidence of a difference between active stimulation and sham (SMD -0.24, 95% CI -0.48 to 0.01, low-quality evidence) for pain intensity. We found no evidence relating to the effectiveness of CES on disability. One study (36 participants) of CES versus sham for quality of life (measured using the FIQ) at short-term follow-up demonstrated a positive effect (MD -25.05 95% CI -37.82 to -12.28, very low-quality evidence). tDCS: Analysis of tDCS studies (27 studies, 747 participants) showed heterogeneity and a difference between active and sham stimulation (SMD -0.43 95% CI -0.63 to -0.22, very low-quality evidence) for pain intensity. This equates to a reduction of 0.82 (95% CI 0.42 to 1.2) points, or a percentage change of 17% (95% CI 9% to 25%) of the control group outcome. This point estimate meets our threshold for a minimum clinically important difference, though the lower confidence interval is substantially below that threshold. We found evidence of small study bias in the tDCS analyses. We did not find evidence that tDCS improved disability. Meta-analysis of studies of tDCS versus sham for quality of life (measured using different scales across studies) at short-term follow-up demonstrated a positive effect (SMD 0.66 95% CI 0.21 to 1.11, low-quality evidence). Adverse events: All forms of non-invasive brain stimulation and sham stimulation appear to be frequently associated with minor or transient side effects and there were two reported incidences of seizure, both related to the active rTMS intervention in the included studies. However many studies did not adequately report adverse events. Authors’ conclusions: There is very low-quality evidence that single doses of high-frequency rTMS of the motor cortex and tDCS may have short-term effects on chronic pain and quality of life but multiple sources of bias exist that may have influenced the observed effects. We did not find evidence that low-frequency rTMS, rTMS applied to the dorsolateral prefrontal cortex and CES are effective for reducing pain intensity in chronic pain. The broad conclusions of this review have not changed substantially for this update. There remains a need for substantially larger, rigorously designed studies, particularly of longer courses of stimulation. Future evidence may substantially impact upon the presented results

Non-invasive brain stimulation techniques for chronic pain

Stimulating the brain without surgery in the management of chronic pain in adults Bottom line: There is a lack of high-quality evidence to support or refute the effectiveness of non-invasive brain stimulation techniques for chronic pain. Background: Electrical stimulation of the brain has been used to address a variety of painful conditions. Various devices are available that can electrically stimulate the brain without the need for surgery or any invasive treatment. There are five main treatment types: repetitive transcranial magnetic stimulation (rTMS) in which the brain is stimulated by a coil applied to the scalp, cranial electrotherapy stimulation (CES) in which electrodes are clipped to the ears or applied to the scalp, transcranial direct current stimulation (tDCS), reduced impedance non-invasive cortical electrostimulation (RINCE) and transcranial random noise stimulation (tRNS) in which electrodes are applied to the scalp. These have been used to try to reduce pain by aiming to alter the activity of the brain. How effective they are is uncertain. Study characteristics: This review update included 94 randomised controlled studies: 42 of rTMS, 11 of CES, 36 of tDCS two of RINCE, two of tRNS and one study which evaluated both tDCS and rTMS. Key findings: rTMS applied to the motor cortex may lead to small, short-term reductions in pain but these effects are not likely to be clinically important. tDCS may reduce pain when compared with sham but for rTMS and tDCS our estimates of benefit are likely to be exaggerated by the small number of participants in each of the studies and limitations in the way the studies were conducted. Low- or very low-quality evidence suggests that low-frequency rTMS and rTMS that is applied to prefrontal areas of the brain are not effective. Low-quality evidence does not suggest that CES is an effective treatment for chronic pain. For all forms of stimulation the evidence is not conclusive and there is substantial uncertainty about the possible benefits and harms of the treatment. Of the studies that clearly reported side effects, short-lived and minor side effects such as headache, nausea and skin irritation were usually reported both with real and sham stimulation. Two cases of seizure were reported following real rTMS. Our conclusions for rTMS, CES, tDCS, and RINCE have not changed substantially in this update. Quality of the evidence: We rated the quality of the evidence from studies using four levels: very low, low, moderate, or high. Very low-quality evidence means that we are very uncertain about the results. High-quality evidence means that we are very confident in the results. We considered all of the evidence to be of low or very low quality, mainly because of bias in the studies that can lead to unreliable results and the small size of the studies, which makes them imprecise

Using Cognitive Walkthrough and Hybrid Prototyping to Gather User Requirements in Early Design Virtual Reality Prototypes

To evaluate Virtual Reality (VR) prototypes usability involves a va-riety of single-perspective or Hybrid methods. The latter has being suggested by literature as offering a more complete sets of requirements highlighting both ‘in-world’ and user interface problems. This paper describes our experiences in using a single-perspective method for gathering user requirements in the REVERIE (Real and Virtual Engagement In Realistic Immersive Environment) project. The study reports results involving nine evaluators who reviewed two hybrid VR prototypes with educational context. It was found that this approach was effective in highlighting a plethora of usability problems covering all as-pects of the two VR prototypes. The performance of our approach was similar to the literature. Although additional validation work is required, we can con-clude that our approach may provide a viable option to evaluate early design VR prototypes when required (e.g., when the expertise needed to use a hybrid method is not available). Future work aims to compare the performance of our approach with two-stage and multiple stage hybrid methods

Estimating brain volume loss after radiation therapy in children treated for posterior fossa tumors (Corpus callosum and whole brain volume changes following radiotherapy in children).

Background More than half of pediatric tumors of central nervous system (CNS) primarily originate in the posterior fossa and are conventionally treated with radiation therapy (RT).Objectives The objective of this study was to establish whether corpus callosum volumes (CCV) and whole brain volumes (WBV) are correlated and to determine the impact of whole-brain lowvs high-dose RT on brain parenchymal volume loss as assessed using each technique.Material and methods Of the 30 identified children (6-12 years) with newly diagnosed posterior fossa tumors treated with cranial RT, including focal and whole-brain RT, suitable imaging was obtained for 23. Radiotherapy regimens were the following: no whole-brain RT (Group 1, n = 7), low-dose whole-brain RT (30 Gy, Group 3, n = 7) in addition to focal boost. Magnetic resonance images (MRIs) were analyzed at baseline and follow-up (median 14 months). The CCVs were manually segmented on midline sagittal slice (n = 23), while WBVs were segmented semi-automatically using Freesurfer (n = 15). This was done twice (6-month interval) for all baseline CCV measurements and 5 randomly selected WBV measurements to establish measurement reproducibility. Correlations between CCV and WBV were investigated and percentage of children demonstrating reduction in CCV or WBV noted.Results Correlation between baseline CCV and WBV was not significant (p = 0.37). Measurement reproducibility was from 6% to -9% for CCV and from 4.8% to -1.2% for WBV. Among the children studied, 30.4% (7/23) had >9% reduction in CCV at follow-up, while 33.3% (5/15) had >1.2% reduction in WBV. Five of 7 patients with CCV loss were not picked up by WBV measurements. Similarly, 3 of 5 patients with WBV loss were not picked up by CCV measurements.Conclusions The CCV and the WBV are unrelated and may indicate different brain parenchymal losses following RT. Up to a third of posterior fossa tumors treated with RT have measurable CCV or WBV loss; incidence was equivalent in lowvs high-dose whole-brain RT

Timing of deep brain stimulation in Parkinson disease: a need for reappraisal?

We review the current application of deep brain stimulation (DBS) in Parkinson disease (PD) and consider the evidence that earlier use of DBS confers long-term symptomatic benefit for patients compared to best medical therapy. Electronic searches were performed of PubMed, Web of Knowledge, Embase, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials to identify all article types relating to the timing of DBS in PD. Current evidence suggests that DBS is typically performed in late stage PD, a mean of 14 to 15 years after diagnosis. Current guidelines recommend that PD patients who are resistant to medical therapies, have significant medication side effects and lengthening off periods, but are otherwise cognitively intact and medically fit for surgery be considered for DBS. If these criteria are rigidly interpreted, it may be that, by the time medical treatment options have been exhausted, the disease has progressed to the point that the patient may no longer be fit for neurosurgical intervention. From the evidence available, we conclude that surgical management of PD alone or in combination with medical therapy results in greater improvement of motor symptoms and quality of life than medical treatment alone. There is evidence to support the use of DBS in less advanced PD and that it may be appropriate for earlier stages of the disease than for which it is currently used. The improving short and long-term safety profile of DBS makes early application a realistic possibility