Why current-carrying magnetic flux tubes gobble up plasma and become thin as a result

It is shown that if a current-carrying magnetic flux tube is bulged at its axial midpoint z=0 and constricted at its axial endpoints z=+h,-h, then plasma will be accelerated from z=+h,-h towards z=0 resulting in a situation similar to two water jets pointed at each other. The ingested plasma convects embedded, frozen-in toroidal magnetic flux from z=+h,-h to z=0. The counter-directed flows collide and stagnate at z=0 and in so doing (i) convert their translational kinetic energy into heat, (ii) increase the plasma density at z~0, and (iii) increase the embedded toroidal flux density at z~0. The increase in toroidal flux density at z~0 increases the toroidal field Bphi and hence increases the magnetic pinch force at z~0 and so causes a reduction of the flux tube radius at z~0. Thus, the flux tube develops an axially uniform cross-section, a decreased volume, an increased density, and an increased temperature. This model is proposed as a likely hypothesis for the long-standing mystery of why solar coronal loops are observed to be axially uniform, hot, and bright.Comment: to appear in Physics of Plasmas 24 pages, 5 figure

SY38-2IMPULSIVITY, MOTIVATIONS AND ADDICTION TO ONLINE GAMES

Introduction. Problematic engagement in online video gaming has been considered recently in the appendix of the DSM-5. Underpinning psychological factors are yet to be clarified, mostly in adult populations. We present data from two studies investigating links between motives to play and impulsivity in one hand and excessive gaming in another hand. Methods. Online studies have been conducted on adult gamers in France (n = 516) and Switzerland (n = 1057). Problematic engagement has been assessed in France by DSM-IV-TR adapted substance dependence criteria (DAS) and by IAT in Switzerland. Motivations have been investigated using Yee's model. Impulsivity has been evaluated using respectively BIS-10 and UPPS-P. The French sample has been compared to heroin users and to healthy controls regarding impulsivity. In the Swiss study, cluster analysis has been conducted to identify subgroups of players regarding their engagement in-game, their motivations to play and their impulsivity. Results. DAS has been found to be predicted by BIS high scores as well as by competition and advancement. Problematic gamers presented higher levels of impulsivity than controls but less than heroin dependents. Three of five clusters were identified to be problematic and linked to high levels of impulsivity, achievement and escapism. Conclusion. Achievement motives to play and high impulsivity have been linked to problematic engagement in online videogames in two different samples evaluated by two different methods. Addiction to online gaming showed a difference in impulsivity traits with substance dependence and healthy controls and subgroups of problem gamers has been characterized. These data could help to design tailored treatments for excessive online gamer

An Easy-to-Use Prognostic Model for Survival Estimation for Patients with Symptomatic Long Bone Metastases

BACKGROUND: A survival estimation for patients with symptomatic long bone metastases (LBM) is crucial to prevent overtreatment and undertreatment. This study analyzed prognostic factors for overall survival and developed a simple, easy-to-use prognostic model. METHODS: A multicenter retrospective study of 1,520 patients treated for symptomatic LBM between 2000 and 2013 at the radiation therapy and/or orthopaedic departments was performed. Primary tumors were categorized into 3 clinical profiles (favorable, moderate, or unfavorable) according to an existing classification system. Associations between prognostic variables and overall survival were investigated using the Kaplan-Meier method and multivariate Cox regression models. The discriminatory ability of the developed model was assessed with the Harrell C-statistic. The observed and expected survival for each survival category were compared on the basis of an external cohort. RESULTS: Median overall survival was 7.4 months (95% confidence interval [CI], 6.7 to 8.1 months). On the basis of the independent prognostic factors, namely the clinical profile, Karnofsky Performance Score, and presence of visceral and/or brain metastases, 12 prognostic categories were created. The Harrell C-statistic was 0.70. A flowchart was developed to easily stratify patients. Using cutoff points for clinical decision-making, the 12 categories were narrowed down to 4 categories with clinical consequences. Median survival was 21.9 months (95% CI, 18.7 to 25.1 months), 10.5 months (95% CI, 7.9 to 13.1 months), 4.6 months (95% CI, 3.9 to 5.3 months), and 2.2 months (95% CI, 1.8 to 2.6 months) for the 4 categories. CONCLUSIONS: This study presents a model to easily stratify patients with symptomatic LBM according to their expected survival. The simplicity and clarity of the model facilitate and encourage its use in the routine care of patients with LBM, to provide the most appropriate treatment for each individual patient. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence

P-73AN INVESTIGATION OF ADDICTIONS (SUBSTANCES AND BEHAVIORS) IN A COMMUNITY SAMPLE

Chemical and behavioral addictions are highly prevalent in our societies. Nevertheless, studies investigating a large panel of addictive behaviors in a community sample are lacking from the current literature on the topic. The aim of the current study is to explore addictive behaviors prevalence, characteristics, and interrelations in a sample of French speaking adults from the general population. Both substances (alcohol, tobacco, cannabis, drugs) and behaviors (gambling, Internet, buying, sport, work, mobile phone, eating) were considered. Several features of these addictive behaviors (involved in the triggering of the behaviors) were considered, namely, frequency, loss of control, hedonic aspects, craving, impact upon the daily living, and emotional contexts. 770 subjects answered to the online survey. Descriptive results will be presented for each conducts and their related features (prevalence, comorbidities, specific characteristics associated with each addictive behaviors). Our study thus provides a detailed overview of the current conducts' prevalence along with their co-occurrences. It also sheds some lights on how these behaviors may have an impact upon the daily living, and eventually turn into problematic behaviors. A particular emphasis is set on some behavioral conducts, like Internet gaming which is particularly salien

The dynamics in applied COVID-19 pharmacotherapy and the influence of national guidance in The Netherlands: a quantitative and qualitative study

OBJECTIVE: At the beginning of the COVID-19 pandemic in the Netherlands, the Dutch Working Party on Antibiotic Policy constructed an advisory document about off-label drug treatment options that was regularly updated with new scientific findings. The aim of this study is to describe the dynamics in applied COVID-19 pharmacotherapy during the first 100 days of the pandemic and to assess how the national advisory document influenced local hospital policies. METHODS: A multicentre observational cohort study was conducted in six hospitals in the Netherlands. Patients with confirmed COVID-19 admitted between 27 February and 7 June 2020 were studied. Drug prescription data were collected and percentages of patients receiving a specific treatment were calculated. These percentages were plotted together with release dates of the national advisory document. Semi-structured in-depth interviews with hospital pharmacists and infectious diseases specialists were conducted to gain insight into the development and implementation of pharmacotherapy treatment protocols in hospitals. RESULTS: Data from 1511 patients (60% men, mean age 66 years) were analysed. From mid-March (hydroxy)chloroquine was being prescribed in all six hospitals to approximately 70% of patients at admission. Frequencies of other off-label treatments were below 2%. In the week of 6 April 2020, the first hospital discontinued prescribing (hydroxy)chloroquine and the last hospital discontinued in the week of 4 May 2020 (total range -19 to +10 days after the national advisory document advised against its use (1 May 2020)). All interviewees (n=6) stated that the hospitals based their policies mainly on the national advisory document but also assessed scientific literature themselves. Order panels were constructed to support prescribing. CONCLUSION: Dutch hospitals opted en masse for (hydroxy)chloroquine as COVID-19 therapy at the start of the pandemic, although the time until the therapy was no longer prescribed differed by several weeks. The fact that hospitals defined pharmacotherapy regimens based on their own assessment of the scientific literature besides the national advisory document can explain this variation

A systematic review of prognostic factors predicting survival in patients with spinal bone metastases

Purpose: For the selection of treatment in patients with spinal bone metastases (SBM), survival estimation plays a crucial role to avoid over- and under-treatment. To aid clinicians in this difficult task, several prediction models have been developed, consisting of many different risk factors. The aim of this systematic review was to identify prognostic factors that are associated with survival in patients with SBM to support development of predictive models. Methods: A systematic review was performed with focus on prognostic factors associated with survival in patients with SBM. Two reviewers independently selected studies for inclusion and assessed the risk of bias. A level of evidence synthesis was performed for each prognostic factor. Inter-observer agreement for the risk of bias assessment was determined by the kappa-statistic. Results: After screening, 142 full-text articles were obtained, of which 22 met the eligibility criteria. A total of 43 different prognostic factors were investigated in the included studies, of which 17 were relevant to pre-treatment survival estimation. The prognostic factors most frequently associated with survival were the primary tumor and the performance status. The prognostic factors most frequently not associated with survival were age, gender, number and location of the SBM and the presence of a pathologic fracture. Conclusions: Prognostication for patients with SBM should be based on an accurate primary tumor classification, combined with a performance score. The benefit of adding other prognostic factors is doubtful

Properties of lightly doped t-J two-leg ladders

We have numerically investigated the doped t-J ladder using exact diagonalization. We have studied both the limit of strong inter-chain coupling and isotropic coupling. The ladder scales to the Luther-Emery liquid regime in the strong inter-chain coupling limit. In this strong coupling limit there is a simple picture of the excitation spectrum that can be continued to explain the behavior at isotropic coupling. At J=0 we have indications of a ferromagnetic ground state. At a large $J/t$ the ladder is phase separated into holes and a Heisenberg ladder. At intermediate coupling the ground state shows hole pairing with a modified d-wave symmetry. The excitation spectrum separates into a limited number of quasiparticles which carry charge $+|e|$ and spin ${1\over 2}$ and a triplet magnon mode. At half-filling the former vanish but the latter evolves continuously into the magnon band of the spin liquid. At low doping the quasiparticles form a dilute Fermi gas with a strong attraction but simultaneously the Fermi wave vector, as would be measured in photoemission, is large. The dynamical structure factors are calculated and are found to be very similar to calculations on 2D clusters

External validation of a model to predict the survival of patients presenting with a spinal epidural metastasis

The surgical treatment of spinal metastases is evolving. The major problem is the selection of patients who may benefit from surgical treatment. One of the criteria is an expected survival of at least 3 months. A prediction model has been previously developed. The present study has been performed in order to validate externally the model and to demonstrate that this model can be generalized to other institutions and other countries than the Netherlands. Data of 356 patients from five centers in Germany, Spain, Sweden, and the Netherlands who were treated for metastatic epidural spinal cord compression were collected. Hazard ratios in the test population corresponded with those of the developmental population. However, the observed and the expected survival were different. Analysis revealed that the baseline hazard function was significantly different. This tempted us to combine the data and develop a new prediction model. Estimating iteratively, a baseline hazard was composed. An adapted prediction model is presented. External validation of a prediction model revealed a difference in expected survival, although the relative contribution of the specific hazard ratios was the same as in the developmental population. This study emphasized the need to check the baseline hazard function in external validation. A new model has been developed using an estimated baseline hazar

Palliative care needs of advanced cancer patients in the emergency department at the end of life: an observational cohort study

Purpose Patients with advanced cancer commonly visit the emergency department (ED) during the last 3 months of life. Identification of these patients and their palliative care needs help initiating appropriate care according to patients' wishes. Our objective was to provide insight into ED visits of advanced cancer patients at the end of life. Methods Adult palliative patients with solid tumours who died = 1 per day. ED visits were initiated by patients and family in 34.0% and 51.9% occurred during out-of-office hours. Dyspnoea (21.0%) or pain (18.6%) were most reported symptoms. Before the ED visit, limitations on life-sustaining treatments were discussed in 33.8%, during or after the ED visit in 70.7%. Median stay at the ED was 3:29 h (range 00:12-18:01 h), and 319 (76.0%) were hospitalized. Median survival was 18 days (IQ range 7-41). One hundred four (24.8%) died within 7 days after the ED visit, of which 71.2% in-hospital. Factors associated with approaching death were lung cancer, neurologic deterioration, dyspnoea, hypercalcemia, and jaundice. Conclusion ED visits of advanced cancer patients often lead to hospitalization and in-hospital deaths. Timely recognition of patients with limited life expectancies and urgent palliative care needs, and awareness among ED staff of the potential of ED-initiated palliative care may improve the end-of-life trajectory of these patients.Development and application of statistical models for medical scientific researc

In vivo renin activity imaging in the kidney of progeroid Ercc1 mutant mice

Changes in the renin-angiotensin system, known for its critical role in the regulation of blood pressure and sodium homeostasis, may contribute to aging and age-related diseases. While the renin-angiotensin system is suppressed during aging, little is known about its regulation and activity within tissues. However, this knowledge is required to successively treat or prevent renal disease in the elderly. Ercc1 is involved in important DNA repair pathways, and when mutated causes accelerated aging phenotypes in humans and mice. In this study, we hypothesized that unrepaired DNA damage contributes to accelerated kidney failure. We tested the use of the renin-activatable near-infrared fluorescent probe ReninSense680™ in progeroid Ercc(1d/-) mice and compared renin activity levels in vivo to wild-type mice. First, we validated the specificity of the probe by detecting increased intrarenal activity after losartan treatment and the virtual absence of fluorescence in renin knock-out mice. Second, age-related kidney pathology, tubular anisokaryosis, glomerulosclerosis and increased apoptosis were confirmed in the kidneys of 24-week-old Ercc(1d/-) mice, while initial renal development was normal. Next, we examined the in vivo renin activity in these Ercc(1d/-) mice. Interestingly, increased intrarenal renin activity was detected by ReninSense in Ercc(1d/-) compared to WT mice, while their plasma renin concentrations were lower. Hence, this study demonstrates that intrarenal RAS activity does not necessarily run in parallel with circulating renin in the aging mouse. In addition, our study supports the use of this probe for longitudinal imaging of altered RAS signaling in aging