448 research outputs found
Age Effects in Postural Control Analyzed via a Principal Component Analysis of Kinematic Data and Interpreted in Relation to Predictions of the Optimal Feedback Control Theory
Optimal feedback control theory suggests that control of movement is focused on movement dimensions that are important for the task's success. The current study tested the hypotheses that age effects would emerge in the control of only specific movement components and that these components would be linked to the task relevance. Fifty healthy volunteers, 25 young and 25 older adults, performed a 80s-tandem stance while their postural movements were recorded using a standard motion capture system. The postural movements were decomposed by a principal component analysis into one-dimensional movement components, PMk, whose control was assessed through two variables, Nk and [sigma]k, which characterized the tightness and the regularity of the neuro-muscular control, respectively. The older volunteers showed less tight and more irregular control in PM2 (N2: -9.2%, p = 0.007; [sigma]2: +14.3.0%, p = 0.017) but tighter control in PM8 and PM9 (N8: +4.7%, p = 0.020; N9: +2.5%, p = 0.043; [sigma]9: -8.8%, p = 0.025). These results suggest that aging effects alter the postural control system not as a whole, but emerge in specific, task relevant components. The findings of the current study thus support the hypothesis that the minimal intervention principle, as described in the context of optimal feedback control (OFC), may be relevant when assessing aging effects on postural control.(VLID)3081018Version of recor
Impact of the COVID-19 pandemic on paediatric urology practice in Europe : a reflection from the European Association of Urology young academic urologists
Mobility and Sporting Activity After Renal Trauma:A Survey Regarding Best Clinical Practice During the Recovery Stage
Objective: To evaluate strategies that are followed after pediatric renal trauma during the recovery stage, with an emphasis on mobility and involvement in subsequent sporting activities. Renal trauma is the most common urogenital trauma in children. The American Association for the Surgery of Trauma (AAST) scale is most commonly used to stratify the severity of injury. There is no consensus in the existing literature with respect to the recovery stage following renal trauma. Methods: A survey was constructed by the European Association of Urology (EAU) â Young Academic Urologists (YAU) Pediatric Urology Working Group and then made digitally available on SurveyMonkey. The survey consists of 15 questions exploring relevant factors and timing to start again with mobility and activity. Results: In total 153 people responded, of whom 107 completed the entire survey. The presence of pain and severity of trauma were acknowledged as most important factors to commence mobilization, whereas presence of hematuria was identified as an additional factor for sporting activity. Regardless of severity of trauma a minimum of 90% of respondents recommend return to noncontact sports within 12 weeks. For contact sports, a minimum of 33% of respondents advised >12 weeks minimum before starting again. A small number of respondents would never allow sporting activities again. Conclusion: The time to allow sporting activity shows high variation among the respondents, some even restricting sporting activities completely. This survey highlights the need for a standardized protocol based on multicenter follow-up data.</p
Modelling the supernova-driven ISM in different environments
We use hydrodynamical simulations in a (256âpc)3 periodic box to model the impact of supernova (SN) explosions on the multiphase interstellar medium (ISM) for initial densities n=0.5-30cmâ3 and SN rates 1-720Myrâ1. We include radiative cooling, diffuse heating, and the formation of molecular gas using a chemical network. The SNe explode either at random positions, at density peaks, or both. We further present a model combining thermal energy for resolved and momentum input for unresolved SNe. Random driving at high SN rates results in hot gas (Tâł106K) filling >90âperâcent of the volume. This gas reaches high pressures (10450âperâcent), residing in small, dense clumps. Such a model might resemble the dense ISM in high-redshift galaxies. Peak driving results in huge radiative losses, producing a filamentary ISM with virtually no hot gas, and a small molecular hydrogen mass fraction (âȘ1âperâcent). Varying the ratio of peak to random SNe yields ISM properties in between the two extremes, with a sharp transition for equal contributions. The velocity dispersion in Hâi remainsâČ10âkmâsâ1 in all cases. For peak driving, the velocity dispersion in Hα can be as high as 70âkmâsâ1 due to the contribution from young, embedded SN remnant
Modelling the supernova-driven ISM in different environments
We use hydrodynamical simulations in a periodic box to
model the impact of supernova (SN) explosions on the multi-phase interstellar
medium (ISM) for initial densities cm and SN rates
Myr. We include radiative cooling, diffuse heating, and the formation of
molecular gas using a chemical network. The SNe explode either at random
positions, at density peaks, or both. We further present a model combining
thermal energy for resolved and momentum input for unresolved SNe. Random
driving at high SN rates results in hot gas ( K) filling %
of the volume. This gas reaches high pressures (
K cm) due to the combination of SN explosions in the hot, low density
medium and confinement in the periodic box. These pressures move the gas from a
two-phase equilibrium to the single-phase, cold branch of the cooling curve.
The molecular hydrogen dominates the mass (%), residing in small, dense
clumps. Such a model might resemble the dense ISM in high-redshift galaxies.
Peak driving results in huge radiative losses, producing a filamentary ISM with
virtually no hot gas, and a small molecular hydrogen mass fraction (%).
Varying the ratio of peak to random SNe yields ISM properties in between the
two extremes, with a sharp transition for equal contributions. The velocity
dispersion in HI remains km s in all cases. For peak
driving the velocity dispersion in H can be as high as km
s due to the contribution from young, embedded SN remnants.Comment: 19 pages, 12 figures, 2 tables. Accepted for publication in MNRAS.
Minor revisions to match published versio
Guideline Adherence of Paediatric Urolithiasis:An EAU Membersâ Survey and Expert Panel Roundtable Discussion
Background: Paediatric nephrolithiasis has increased globally, requiring standardized recommendations. This study aims to assess the paediatric urolithiasis care between EAU members along with the statements of three experts in this field. Methods: The results of an electronic survey among EAU members comparing the guideline recommendations to their current practice managing paediatric nephrolithiasis in 74 centres are contrasted with insights from an expert-panel. The survey consisted of 20 questions in four main sections: demographics, instrument availability, surgical preferences and follow-up preferences. Experts were asked to give insights on the same topics. Results: A total of 74 responses were received. Computerised Tomography was predominantly used as the main imaging modality over ultrasound. Lack of gonadal protection during operations was identified as an issue. Adult instruments were used frequently instead of paediatric instruments. Stone and metabolic analysis were performed by 83% and 63% of the respondents respectively. Conclusions: Percutaneous Nephrolithotomy is the recommended standard treatment for stones > 20 mm, 12% of respondents were still performing shockwave lithotripsy despite PNL, mini and micro-PNL being available. Children have a high risk for recurrence yet stone and metabolic analysis was not performed in all patients. Expert recommendations may guide clinicians towards best practice
Hepatitis C virus cell-cell transmission and resistance to direct-acting antiviral agents
Hepatitis C virus (HCV) is transmitted between hepatocytes via classical cell entry but also uses direct cell-cell transfer to infect neighboring hepatocytes. Viral cell-cell transmission has been shown to play an important role in viral persistence allowing evasion from neutralizing antibodies. In contrast, the role of HCV cell-cell transmission for antiviral resistance is unknown. Aiming to address this question we investigated the phenotype of HCV strains exhibiting resistance to direct-acting antivirals (DAAs) in state-of-the-art model systems for cell-cell transmission and spread. Using HCV genotype 2 as a model virus, we show that cell-cell transmission is the main route of viral spread of DAA-resistant HCV. Cell-cell transmission of DAA-resistant viruses results in viral persistence and thus hampers viral eradication. We also show that blocking cell-cell transmission using host-targeting entry inhibitors (HTEIs) was highly effective in inhibiting viral dissemination of resistant genotype 2 viruses. Combining HTEIs with DAAs prevented antiviral resistance and led to rapid elimination of the virus in cell culture model. In conclusion, our work provides evidence that cell-cell transmission plays an important role in dissemination and maintenance of resistant variants in cell culture models. Blocking virus cell-cell transmission prevents emergence of drug resistance in persistent viral infection including resistance to HCV DAAs
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Fielding the NIF Cryogenic Ignition Target
The United States Department of Energy has embarked on a campaign to conduct credible fusion ignition experiments on the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in 2010. The target assembly specified for this campaign requires the formation of a deuterium/tritium (DT) fuel ice layer on the inside of a 2 millimeter diameter capsule positioned at the center of a 9 millimeter long by 5 millimeter diameter cylinder, called a hohlraum. The ice layer requires micrometer level accuracy and must be formed and maintained at temperatures below 19 K. At NIF shot time, the target must be positioned at the center of the NIF 10 meter diameter target chamber, aligned to the laser beam lines and held stable to less than 7 micrometers rms. We have completed the final design and are integrating the systems necessary to create, characterize and field the cryogenic target for ignition experiments. These designs, with emphasis on the challenges of fielding a precision cryogenic positioning system will be presented
A multi-institutional European comparative study of open versus robotic-assisted laparoscopic ureteral reimplantation in children with high grade (IVâV) vesicoureteral reflux
Introduction: Traditionally, open ureteral reimplantation (OUR) has been the standard treatment for primary vesicoureteral reflux (VUR) requiring reimplantation. Robotic-assisted laparoscopic ureteral reimplantation (RALUR) is gaining popularity and high success rates have been reported. Objective: In this multi-institutional study, we aimed to compare the perioperative and postoperative outcomes of OUR and RALUR for high-grade (IV + V) VUR in children. Study design: A retrospective evaluation was performed collecting data from 135 children (0â18 years) who underwent high grade VUR surgical correction at nine European institutions between 01/01/2009 and 01/12/2020, involving either open or robotic approaches. Institutional review board approval was obtained. Patients with lower grades of VUR (â€III), previous history of open or endoscopic ureteral surgery, neurogenic bladder, or refluxing megaureter in need of ureteral tapering were excluded. Pre-, peri- and post-operative data were statistically compared. Results: Overall, 135 children who underwent either OUR (n = 68), or RALUR (n = 67) were included, and their clinic and demographic features were collected. The mean age of the open group was 11 months (interquartile range [IQR] 9.9â16.6 months), in the RALUR group it was 59 months (IQR 29â78mo) (p < 0.01); the open cohort had a weight of 11 kg (IQR 9.9â16.6 kg) while the RALUR group had 19 kg (IQR 13â25 kg) (p < 0.01). No significant differences were found for intraoperative (1.5 % vs 7.5 %, p = 0.09) or for postoperative complication rates (7.4 % vs 9 %, p = 0.15). Favorable outcomes were reported in the RALUR group: shorter time to stooling (1 vs 2 days), fewer indwelling urethral catheter days (1 vs 5 days), perioperative drain insertion time (1 vs 5 days) and a shorter length of hospital stay (2 vs 5 days) (p < 0.01). The success rate was 94.0 % and 98.5 % in the open and RALUR groups, respectively. The long-term clinical success rates from both groups was comparable:42 vs 23 months for open and RALUR, respectively. Discussion: This study reported a large multicentric experience focusing on high grade VUR. Furthermore, this study compares favorably to OUR in a safety analysis. There was also a trend towards higher success rates with RALUR utilizing an extravesical approach which has not been previously reported. Conclusion: RALUR is an efficacious and safe platform to use during ureteral reimplantation for high grade VUR. The overall peri-operative and post-operative complication rates are at least equivalent to OUR, but it is associated with a faster functional recovery and time to discharge. Medium to long term success rates are also equivalent to OUR.</p
Enhanced electron acceleration by high-intensity lasers in extended (confined) preplasma in cone targets
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