451 research outputs found
A logarithmic epiperimetric inequality for the obstacle problem
For the general obstacle problem, we prove by direct methods an epiperimetric
inequality at regular and singular points, thus answering a question of Weiss
(Invent. Math., 138 (1999), 23--50). In particular at singular points we
introduce a new tool, which we call logarithmic epiperimetric inequality, which
yields an explicit logarithmic modulus of continuity on the regularity of
the singular set, thus improving previous results of Caffarelli and Monneau
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Long-Term Experience of Chemoradiotherapy Combined with Deep Regional Hyperthermia for Organ Preservation in High-Risk Bladder Cancer (Ta, Tis, T1, T2).
BackgroundThe aim of this study was to evaluate the efficacy and safety of chemoradiotherapy (RCT) combined with regional deep hyperthermia (RHT) of high-risk bladder cancer after transurethral resection of bladder tumor (TUR-BT).Materials and methodsBetween 1982 and 2016, 369 patients with pTa, pTis, pT1, and pT2 cN0-1 cM0 bladder cancer were treated with a multimodal treatment after TUR-BT. All patients received radiotherapy (RT) of the bladder and regional lymph nodes. RCT was administered to 215 patients, RCT + RHT was administered to 79 patients, and RT was used in 75 patients. Treatment response was evaluated 4-6 weeks after treatment with TUR-BT.ResultsComplete response (CR) overall was 83% (290/351), and in treatment groups was RT 68% (45/66), RCT 86% (178/208), and RCT + RHT 87% (67/77). CR was significantly improved by concurrent RCT compared with RT (odds ratio [OR], 2.32; 95% confidence interval [CI], 1.05-5.12; p = .037), less influenced by hyperthermia (OR, 2.56; 95% CI, 0.88-8.00; p = .092). Overall survival (OS) after RCT was superior to RT (hazard ratio [HR], 0.7; 95% CI, 0.50-0.99; p = .045). Five-year OS from unadjusted Kaplan-Meier estimates was RCT 64% versus RT 45%. Additional RHT increased 5-year OS to 87% (HR, 0.32; 95% CI, 0.18-0.58; p = .0001). RCT + RHT compared with RCT showed a significantly better bladder-preservation rate (HR, 0.13; 95% CI, 0.03-0.56; p = .006). Median follow-up was 71 months. The median number of RHT sessions was five.ConclusionThe multimodal treatment consisted of a maximal TUR-BT followed by RT; concomitant platinum-based chemotherapy combined with RHT in patients with high-grade bladder cancer improves local control, bladder-preservation rate, and OS. It offers a promising alternative to surgical therapies like radical cystectomy.Implications for practiceRadical cystectomy with appropriate lymph node dissection has long represented the standard of care for muscle-invasive bladder cancer in medically fit patients, despite many centers reporting excellent long-term results for bladder preserving strategies. This retrospective analysis compares different therapeutic modalities in bladder-preservation therapy. The results of this study show that multimodal treatment consisting of maximal transurethral resection of bladder tumor followed by radiotherapy, concomitant platinum-based chemotherapy combined with regional deep hyperthermia in patients with Ta, Tis, T1-2 bladder carcinomas improves local control, bladder-preservation rate, and survival. More importantly, these findings offer a promising alternative to surgical therapies like radical cystectomy. The authors hope that, in the future, closer collaboration between urologists and radiotherapists will further improve treatments and therapies for the benefit of patients
Multiphoton microscopy for the investigation of dermal penetration of nanoparticle-borne drugs
Multiphoton microscopy of a dually fluorescence-labeled model system in excised human skin is employed for high resolution three dimensional visualization in order to study the release, accumulation and penetration properties of drugs released from nanoscale carrier particles in dermal administration. Polymer particles were covalently labeled with fluorescein while Texas Red as a drug-model was dissolved in the particle to be released to the formulation matrix. Single nanoparticles on skin could easily be localized and imaged with diffraction limited resolution. The temporal evolution of the fluorescent drug-model concentration in various skin compartments over more than five hours was investigated by multiphoton spectral imaging of the same area of the specimen. The three dimensional penetration profile of the drug-model in correlation with skin morphology and particle localization information are obtained by a multiple laser line excitation experiment. Multiphoton microscopy combined with spectral imaging was found to allow non invasive long term studies of particle-borne drug-model penetration into the skin with sub cellular resolution. By dual color labeling a clear discrimination between particle-bound and released drug-model was possible. The introduced technique was shown to be a powerful tool in revealing the dermal penetration properties and pathways of drugs and nanoscale drug vehicles on microscopic level
Parametric oscillations in planetary wheel gearboxes
Разработана математическая модель параметрических колебаний в планетарных колесных редукторах (ПКР) троллейбусов. Модель учитывает циклические деформации тонкостенного обода и зубьев в зацеплении эпицикла с сателлитами. Дифференциальное уравнение колебаний эпицикла приведено к виду уравнений Матье-Хилла с переменными периодическими коэффициентами. На основании диаграммы Айнса-Стретта определены области неустойчивости параметрических колебаний "критериального элемента" – тонкостенного эпицикла для прямозубых и косозубых передач с учетом влияния зазоров в зацеплениях. Установлены диапазоны значений критических скоростей движения троллейбусов, соответствующие проявлению первых трех параметрических резонансов эпицикла ПКР в составе конструкций ведущих мостов 1-го и 3-го поколений известных фирм-производителей. Обоснован критерий виброустойчивости эпицикла, установлены расчетные значения вероятности параметрических резонансов. Теоретически подтвержден положительный эффект от применения косозубого зацепления в ПКР, что обеспечивает минимальную глубину пульсации жесткости, сужение области неустойчивости параметрических колебаний эпицикла, уменьшает вероятность зарождения и развития усталостных трещин.A mathematical model of parametric oscillations in the planetary wheel gearboxes (PWG) of the trolley buses has been developed. The model takes into account the cyclic deformations of a thin-walled rim and teeth in the meshing of the epicycle with the satellites. The differential equation of the oscillations of the epicycle is reduced to the form of the Mathieu-Hill equations with variable periodic coefficients. On the basis of the Ains-Strett diagram, regions of instability of parametric oscillations of the "criteria element" – a thin-walled epicycle for spur and helical gears are determined, taking into account the influence of gaps in the gears. The ranges of values of the critical velocities of the trolley buses corresponding to the manifestation of the first three parametric resonances of the PWG epicycle in the structure of the traction bridges of the 1st and 3rd generations of well known manufacturing companies are established. The criterion of the vibration stability of the epicycle is substantiated, the calculated values of the probabilities of parametric resonances are established. Theoretically, the positive effect of helical engagement in PWG has been confirmed, which provides a minimum depth of hardness pulsation, a narrowing of the instability region of parametric oscillations of the epicycle, reduces the probability of nucleation and development of fatigue cracks
Differences in race history by distance of recreational endurance runners from The NURMI Study (Step 2)
Few studies were developed to understand the relationship between running characteristics and motivation. The purpose of this study was to assess the relationship between running event history, running experience, and best race performances in recreational distance runners. We used a web survey to obtain information regarding running experience, racing history, and periodization training routines/exercise habits, including weekly volumes and daily mileage and duration across periods and conditions. Associations between variables were conducted with the Chi-square test (χ; nominal scale) and Wilcoxon test. Multiple linear regression analysis and multivariate linear regression were performed. Concerning the participants' motive for exercising, a significant difference was identified between the race distance subgroups (p < 0.001), where 58% of M/UM runners exercised for performance (n = 38) and 64% of HM runners (n = 57) and 57% of 10 km runners (n = 52) exercised for recreational purposes. A significant difference was found in the number of years of running completed without taking a break (p = 0.004), with marathoners/ultramarathoners reporting the most years. Runners competing in different race distances such as 10 km, half-marathon, marathon, and ultra-marathon presented differences in training background and habits according to the distance of preference
Differences in training characteristics of recreational endurance runners by race distance - results from the NURMI Study (Step 2)
BACKGROUND
Although runner's profiles were previously investigated, information on the training frequency and training distance for short (5 km, 10 km) and long-distance (>21 km) running is absent. The present study aimed to investigate the associations between training routines and exercise habits of recreational endurance runners considering self-reported preferred race distance [10 km, half-marathon (HM), and marathon/ultra-marathon (M/UM)] subgroups.
METHODS
This is a cross-sectional study, sampling 154 recreational runners of both sexes. A web survey was used for data collection regarding age, sex, preferred distance (10-km, HM, M/UM), training routines, exercise habits, and periodized training routines. The Chi-square test (Cramer's V) and Kruskal-Wallis test (Eta-Squared η) with effect sizes were used for comparisons between race distances.
RESULTS
Significant differences were shown for anthropometric, training, and periodization characteristics. Highly significant differences were found between subgroups for the number of sessions, running kilometers, and training hours at all periods and within all four preparation conditions. M/UM runners were training more frequently, for longer durations, and ran greater distances each week.
CONCLUSION
This finding supports the notion that training habits and periodization characteristics are different for different race distances (10-km, half marathon, marathon, and ultramarathon)
Quantum Tests of the Foundations of General Relativity
The role of the equivalence principle in the context of non-relativistic
quantum mechanics and matter wave interferometry, especially atom beam
interferometry, will be discussed. A generalised form of the weak equivalence
principle which is capable of covering quantum phenomena too, will be proposed.
It is shown that this generalised equivalence principle is valid for matter
wave interferometry and for the dynamics of expectation values. In addition,
the use of this equivalence principle makes it possible to determine the
structure of the interaction of quantum systems with gravitational and inertial
fields. It is also shown that the path of the mean value of the position
operator in the case of gravitational interaction does fulfill this generalised
equivalence principle.Comment: Classical and Quantum Gravity 15, 13 (1998
Challenges and barriers for a sustainable transport system – exploring the potential to enact change
This report is divided into three parts; the first part summarizes the results from a workshopconducted within the TRANSFORuMproject. The second part presents the results of interviewscarried out with different experts discussing the different goals and their perceptionsof what might prevent or delay appropriate implementation. The third part is based on a literature reviewdiscussing how to overcome or remove the various barriersand challenges. The overall aim ofthe studies presented in this report is to identify barriers but also to present necessary steps which need to be takenin order to help achieving the goals.The term "Barrier" relates to something which prevents some form of progress or movement, while "Challenge" can be something difficult but also something which is regarded as stimulating; or an opportunity
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