Dielectric wakefield researches

Excitation of wakefields in cylindrical dielectric waveguide/resonator by a sequence of relativistic electron bunches was investigated using an electron linac «Almaz-2» (4.5 МeV, 6·10³ bunches of duration 60 ps and charge 0.32 nC each). Energy spectrum of electrons, radial topography and longitudinal distribution of wakefield, and total energy of excited wakefield were measured by means of magnetic analyzer, high frequency probe, and a sensitive calorimeter.Исследовано возбуждение кильватерных полей в цилиндрическом диэлектрическом волноводе/резонаторе последовательностью релятивистских электронных сгустков на линейном электронном ускорителе «Алмаз-2» (4.5 МэВ, 6•10³ сгустков длительностью 60 пс и зарядом 0.32 нКл каждый). Измерены энергетические спектры электронов, радиальная топография и продольное распределение кильватерного поля и его энергия с помощью магнитного анализатора, ВЧ-зондов и чувствительного калориметра.Досліджено збудження кільватерних полів у циліндричному діелектричному хвилеводі/резонаторі регулярною послідовністю релятивістських електронних згустків на лінійному електронному прискорювачі «Алмаз-2» (4.5 МеВ, 6·10³ згустків тривалістю 60 пс і зарядом 0.32 нКл кожний). Виміряні енергетичні спектри електронів, радіальна топографія та поздовжній розподіл кільватерного поля та його енергія за допомогою магнітного аналізатора, ВЧ-зондів і чутливого калориметра

On possibility of measurement of the electron beam energy using absorption of radiation by electrons in a magnetic field

The possibility of the precise measurement of the electron beam energy using absorption of radiation by electrons in a static and homogeneous magnetic field in a range up to a few hundred GeV energies, was considered in [1]. With the purpose of experimental checking of this method in a range of several tens MeV energies, the possibility of measurement of absolute energy of the electron beam energy with relative accuracy up to 10^{-4} is examined in details.Comment: 14 pages, 10 figure

Validation of a commercially available markerless motion-capture system for trunk and lower extremity kinematics during a jump-landing assessment

Context: Field-based, portable motion-capture systems can be used to help identify individuals at greater risk of lower extremity injury. Microsoft Kinect-based markerless motion-capture systems meet these requirements; however, until recently, these systems were generally not automated, required substantial data postprocessing, and were not commercially available. Objective: To validate the kinematic measures of a commercially available markerless motion-capture system. Design: Descriptive laboratory study. Setting: Laboratory. Patients or Other Participants: A total of 20 healthy, physically active university students (10 males, 10 females; age ¼ 20.50 6 2.78 years, height ¼ 170.36 6 9.82 cm, mass ¼ 68.38 6 10.07 kg, body mass index ¼ 23.50 6 2.40 kg/m2). Intervention(s): Participants completed 5 jump-landing trials. Kinematic data were simultaneously recorded using Kinect-based markerless and stereophotogrammetric motion-capture systems. Main Outcome Measure(s): Sagittal- and frontal-plane trunk, hip-joint, and knee-joint angles were identified at initial ground contact of the jump landing (IC), for the maximum joint angle during the landing phase of the initial landing (MAX), and for the joint-angle displacement from IC to MAX (DSP). Outliers were removed, and data were averaged across trials. We used intraclass correlation coefficients (ICCs [2,1]) to assess intersystem reliability and the paired-samples t test to examine mean differences (a < .05). Results: Agreement existed between the systems (ICC range ¼1.52 to 0.96; ICC average ¼ 0.58), with 75.00% (n ¼ 24/ 32) of the measures being validated (P < .05). Agreement was better for sagittal- (ICC average ¼ 0.84) than frontal- (ICC average ¼ 0.35) plane measures. Agreement was best for MAX (ICC average ¼ 0.77) compared with IC (ICC average ¼ 0.56) and DSP (ICC average ¼ 0.41) measures. Pairwise comparisons identified differences for 18.75% (6/32) of the measures. Fewer differences were observed for sagittal- (0.00%; 0/15) than for frontal- (35.29%; 6/17) plane measures. Between-systems differences were equivalent for MAX (18.18%; 2/11), DSP (18.18%; 2/11), and IC (20.00%; 2/10) measures. The markerless system underestimated sagittal-plane measures (86.67%; 13/15) and overestimated frontal-plane measures (76.47%; 13/ 17). No trends were observed for overestimating or underestimating IC, MAX, or DSP measures. Conclusions: Moderate agreement existed between markerless and stereophotogrammetric motion-capture systems. Better agreement existed for larger (eg, sagittal-plane, MAX) than for smaller (eg, frontal-plane, IC) joint angles. The DSP angles had the worst agreement. Markerless motion-capture systems may help clinicians identify individuals at greater risk of lower extremity injury

Relationship between concussion history and concussion knowledge, attitudes, and disclosure behavior in high school athletes

Objective: Examine the association between self-reported concussion history and measures of concussion knowledge, attitude, and disclosure behavior. Design: Cross-sectional survey. Setting: Classroom. Participants: A convenience sample of high school athletes (n = 167; mean age = 15.7 years) from multiple sports completed a validated survey. Independent Variables: Concussion history (main predictor) was defined as the number of self-recalled concussions during participants' high school career. Main Outcome Measures: The outcomes were recalled concussion disclosure behavior (3 measures) and scales assessing both concussion knowledge and concussion attitude. Results: A greater number of previous concussions was associated with worse attitude to concussion and negative concussion disclosure behavior. For every 3 additional self-recalled concussions, there was a mean decrease of 7.2 points (range of possible scores = 14-98) in concussion attitude score (P = 0.002), a 48% decrease in the self-reported proportion of concussion events disclosed (P = 0.013), and an increased prevalence of self-reported participation in games (67%) and practices (125%) while experiencing signs and symptoms of concussion (P < 0.001). Increased concussion history did not affect concussion knowledge score (P = 0.333). Conclusions: Negative trends in concussion disclosure behavior were identified in youth athletes with a positive history of concussion. Improving disclosure in this subgroup will require targeted efforts addressing negative attitude to concussion

A Novel Culture-Dependent Gesture Selection System for a Humanoid Robot Performing Greeting Interaction

In human-robot interaction, it is important for the robots to adapt to our ways of communication. As humans, rules of non-verbal communication, including greetings, change depending on our culture. Social robots should adapt to these specific differences in order to communicate effectively, as a correct way of approaching often results into better acceptance of the robot. In this study, a novel greeting gesture selection system is presented and an experiment is run using the robot ARMAR-IIIb. The robot performs greeting gestures appropriate to Japanese culture; after interacting with German participants, the selection should become appropriate to German culture. Results show that the mapping of gesture selection evolves successfully

A Screen for Morphological Complexity Identifies Regulators of Switch-like Transitions between Discrete Cell Shapes

The way in which cells adopt different morphologies is not fully understood. Cell shape could be a continuous variable or restricted to a set of discrete forms. We developed quantitative methods to describe cell shape and show that Drosophila hemocytes in culture are a heterogeneous mixture of five discrete morphologies. In an RNAi screen of genes affecting the morphological complexity of heterogeneous populations, we found that most genes regulate the transition between discrete shapes rather than generating new morphologies. In particular, we identified a subset of genes, including the tumour suppressor PTEN, that decrease the heterogeneity of the population leading to populations enriched in rounded or elongated forms. We show that these genes have a highly conserved function as regulators of cell shape in both mouse and human metastatic melanoma cells

Risk of fentanyl-involved overdose among those with past year incarceration: Findings from a recent outbreak in 2014 and 2015

Overdose is the leading cause of unintentional injury-related death. Rhode Island (RI) has the highest rate of illicit drug use nationally and the 5th highest overdose mortality rate. RI has experienced an outbreak of fentanyl-related overdoses. In incarcerated populations, risk of overdose is greatly elevated. However, little is known about fentanyl-related overdose post-release. In the current analyses, we identify changes in fentanyl-related fatal overdose among those who died in 2014 and 2015 who were incarcerated in the year before death. We linked data from the RI Office of the Medical Examiner with records from the RI Department of Corrections. We calculated risk ratios and 95% confidence intervals using log-binomial regression to compare risk of fentanyl-involved overdose death. We also compared median time to death since release, median sentence length, and median number of incarcerations in 2014 and 2015. Results indicate that the risk of dying of a fentanyl-related overdose increased (RR: 1.99 (95% CI: 1.11–3.57, p = 0.014)) from 2014 to 2015 among those with past year incarceration. This study is one of the first to describe fentanyl-related fatal overdose among those with past year incarceration. In 2015 the median sentence was longer among those with a fentanyl-related overdose death and the median time from release to death among all who had past year incarceration extended past 90 days. Access to medications for addiction treatment, overdose education, and naloxone should be available during community re-entry and extended beyond the early post-release period

Trunk and lower extremity movement patterns, stress fracture risk factors, and biomarkers of bone turnover in military trainees

Context: Military service members commonly sustain lower extremity stress fractures (SFx). How SFx risk factors influence bone metabolism is unknown. Understanding how SFx risk factors influence bone metabolism may help to optimize risk-mitigation strategies. Objective: To determine how SFx risk factors influence bone metabolism. Design: Cross-sectional study. Setting: Military service academy. Patients or Other Participants: Forty-five men (agepre ¼ 18.56 6 1.39 years, heightpre ¼ 176.95 6 7.29 cm, masspre ¼ 77.20 6 9.40 kg; body mass indexpre ¼ 24.68 6 2.87) who completed Cadet Basic Training (CBT). Individuals with neurologic or metabolic disorders were excluded. Intervention(s): We assessed SFx risk factors (independent variables) with (1) the Landing Error Scoring System (LESS), (2) self-reported injury and physical activity questionnaires, and (3) physical fitness tests. We assessed bone biomarkers (dependent variables; procollagen type I amino-terminal propeptide [PINP] and cross-linked collagen telopeptide [CTx-1]) via serum. Main Outcome Measure(s): A markerless motion-capture system was used to analyze trunk and lower extremity biomechanics via the LESS. Serum samples were collected post-CBT; enzyme-linked immunosorbent assays determined PINP and CTx-1 concentrations, and PINP: CTx-1 ratios were calculated. Linear regression models demonstrated associations between SFx risk factors and PINP and CTx-1 concentrations and PINP: CTx-1 ratio. Biomarker concentration mean differences with 95% confidence intervals were calculated. Significance was set a priori using a ≤ .10 for simple and a ≤ .05 for multiple regression analyses. Results: The multiple regression models incorporating LESS and SFx risk factor data predicted the PINP concentration (R2 ¼ 0.47, P ¼ .02) and PINP: CTx-1 ratio (R2 ¼ 0.66, P ¼ .01). The PINP concentration was increased by foot internal rotation, trunk flexion, CBT injury, sit-up score, and pre- to post-CBT mass changes. The CTx-1 concentration was increased by heel-to-toe landing and post-CBT mass. The PINP: CTx-1 ratio was increased by foot internal rotation, lower extremity sagittal-plane displacement (inversely), CBT injury, sit-up score, and pre- to post-CBT mass changes. Conclusions: Stress fracture risk factors accounted for 66% of the PINP: CTx-1 ratio variability, a potential surrogate for bone health. Our findings provide insight into how SFx risk factors influence bone health. This information can help guide SFx risk-mitigation strategies