Коректність задачі Коші для нескінченної системи нелінійних осциляторів, розміщених на двовимірній решітці

Стаття присвячена вивченню нескінченної системи диференціальних рівнянь, яка описує нескінченний ланцюг лінійно зв’язаних нелінійних осциляторів. Отримано результати про існування та єдиність локального та глобального розв’язків задачі Коші.The article deals with infinite systems of differential equations that describe infinite system of nonlinear oscillators on 2D–lattice. It is obtained results on existence and uniqueness of local and global solutions to the Cauchy problem

№ 121. Протокол допиту Володимира Чехівського від 17 липня 1929 р.

Background: The results from studies on adverse drug effects in electronic health care databases may vary due to multiple reasons, one of them being differences in (left and right) censoring mechanisms between databases. Such censoring mechanisms can be features of the database and are therefore hard to avoid by the researcher. Objectives: To assess the impact of left and right censoring on estimates of adverse effects of drugs. Methods: We used simulation studies to assess the impact of left and right censoring (differential or nondifferential) on bias of estimates of adverse drug effects. We studied three types of adverse drug effects: (1) a constant exposure effect; (2) a first-time exposure effect (e.g. anaphylactic reaction); and (3) a cumulative exposure effect. Effects were expressed as incidence rate ratios and estimated using Poisson regression. Results: Non-random censoring biased all three types of adverse drug effects. Random right censoring did not result in a bias. Random left-censoring resulted in an overestimation of the drug effect in case of a cumulative exposure effect and an underestimation of the drug effect in case of a first-time exposure effect. For example, when 50% of the observation time was left censored, the observed first-time exposure effect was RR 1.4 instead of the true RR 3.0 and a cumulative exposure effect of RR 1.15 per unit time exposure was observed instead of the true RR 1.1 per unit time exposure. The impact of censoring depended on exposure prevalence, outcome incidence, and duration of the time-interval that was censored. Conclusions: Censoring may differentially impact estimates of exposure effect in studies of constant, firsttime, and cumulative exposure effects. Researchers should be aware of this when combining data from multiple databases or when comparing drug effects across databases

The ethics of ‘Trials within Cohorts’ (TwiCs): 2nd international symposium - London, UK. 7-8 November 2016

On 7-8 th November 2016, 60 people with an interest in the ‘ Trials within Cohorts ’ (TwiCs) approach for randomised controlled trial design met in London. The purpose of this 2 nd TwiCs international symposium was to share perspectives and experiences on ethical aspects of the TwiCs design, discuss how TwiCs relate to the current ethical frame- work, provide a forum in which to discuss and debate ethical issues and identify future directions for conceptual and empirical research. The symposium was supported by the Wellcome Trust and the NIHR CLAHRC Yorkshire and Humber and organised by members of the TwiCs network led by Clare Relton and attended by people from the UK, the Netherlands, Norway, Canada and USA. The two-day sympo- sium enabled an international group to meet and share experiences of the TwiCs design (also known as the ‘ cohort multiple RCT design ’ ), and to discuss plans for future research. Over the two days, invited plenary talks were interspersed by discussions, posters and mini pre- sentations from bioethicists, triallists and health research regulators. Key findings of the symposium were: (1) It is possible to make a compelling case to ethics committees that TwiCs designs are ap- propriate and ethical; (2) The importance of wider considerations around the ethics of inefficient trial designs; and (3) some questions about the ethical requirements for content and timing of informed consent for a study using the TwiCs design need to be decided on a case-by-case basis

Reception Test of Petals for the End Cap TEC+ of the CMS Silicon Strip Tracker

The silicon strip tracker of the CMS experiment has been completed and was inserted into the CMS detector in late 2007. The largest sub system of the tracker are its end caps, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted onto the TEC support structures. Each end cap consists of 144 such petals, which were built and fully qualified by several institutes across Europe. Fro

Integration of the End Cap TEC+ of the CMS Silicon Strip Tracker

The silicon strip tracker of the CMS experiment has been completed and inserted into the CMS detector in late 2007. The largest sub-system of the tracker is its end cap system, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted into the TEC support structures. Each end cap consists of 144 petals, and the insertion of these petals into the end cap structure is referred to as TEC integration. The two end caps were integrated independently in Aachen (TEC+) and at CERN (TEC--). This note deals with the integration of TEC+, describing procedures for end cap integration and for quality control during testing of integrated sections of the end cap and presenting results from the testing

Risk patterns in drug safety study using relative times by accelerated failure time models when proportional hazards assumption is questionable : An illustrative case study of cancer risk of patients on glucose-lowering therapies

Observational drug safety studies may be susceptible to confounding or protopathic bias. This bias may cause a spurious relationship between drug exposure and adverse side effect when none exists and may lead to unwarranted safety alerts. The spurious relationship may manifest itself through substantially different risk levels between exposure groups at the start of follow-up when exposure is deemed too short to have any plausible biological effect of the drug. The restrictive proportional hazards assumption with its arbitrary choice of baseline hazard function renders the commonly used Cox proportional hazards model of limited use for revealing such potential bias. We demonstrate a fully parametric approach using accelerated failure time models with an illustrative safety study of glucose-lowering therapies and show that its results are comparable against other methods that allow time-varying exposure effects. Our approach includes a wide variety of models that are based on the flexible generalized gamma distribution and allows direct comparisons of estimated hazard functions following different exposure-specific distributions of survival times. This approach lends itself to two alternative metrics, namely relative times and difference in times to event, allowing physicians more ways to communicate patient's prognosis without invoking the concept of risks, which some may find hard to grasp. In our illustrative case study, substantial differences in cancer risks at drug initiation followed by a gradual reduction towards null were found. This evidence is compatible with the presence of protopathic bias, in which undiagnosed symptoms of cancer lead to switches in diabetes medication. Copyright © 2015 John Wiley & Sons, Ltd

Electron Identification up to 100 GeV by Means of Transition Radiation

We report on measurements with different transition radiation detector configurations, which were performed with the aim of pion-electron-discrimination in the momentum range between 1 GeV/c and 100 GeV/c. The test set-up consisted of four polypropylene fibre radiators with proportional wire chambers as photon detectors. We tested about 50 combinations varying the diameter of the fibre, the density of the radiators and the thickness of the chambers. Results of measurements performed at a DESY testbeam at energies between 0.6 and 6.6 GeV and of extrapolations to particle momenta up to 100 GeV/c are discussed. At 95% electron efficiency a pion contamination of a few per cent can be achieved over the full energy range

Electron Identification up to 100 GeV by Means of Transition Radiation

We report on measurements with different transition radiation detector configurations, which were performed with the aim of pion-electron-discrimination in the momentum range between 1 GeV/c and 100 GeV/c. The test set-up consisted of four polypropylene fibre radiators with proportional wire chambers as photon detectors. We tested about 50 combinations varying the diameter of the fibre, the density of the radiators and the thickness of the chambers. Results of measurements performed at a DESY testbeam at energies between 0.6 and 6.6 GeV and of extrapolations to particle momenta up to 100 GeV/c are discussed. At 95% electron efficiency a pion contamination of a few per cent can be achieved over the full energy range

Impact of censoring on estimates of adverse drug effects: A simulation study

Background: The results from studies on adverse drug effects in electronic health care databases may vary due to multiple reasons, one of them being differences in (left and right) censoring mechanisms between databases. Such censoring mechanisms can be features of the database and are therefore hard to avoid by the researcher. Objectives: To assess the impact of left and right censoring on estimates of adverse effects of drugs. Methods: We used simulation studies to assess the impact of left and right censoring (differential or nondifferential) on bias of estimates of adverse drug effects. We studied three types of adverse drug effects: (1) a constant exposure effect; (2) a first-time exposure effect (e.g. anaphylactic reaction); and (3) a cumulative exposure effect. Effects were expressed as incidence rate ratios and estimated using Poisson regression. Results: Non-random censoring biased all three types of adverse drug effects. Random right censoring did not result in a bias. Random left-censoring resulted in an overestimation of the drug effect in case of a cumulative exposure effect and an underestimation of the drug effect in case of a first-time exposure effect. For example, when 50% of the observation time was left censored, the observed first-time exposure effect was RR 1.4 instead of the true RR 3.0 and a cumulative exposure effect of RR 1.15 per unit time exposure was observed instead of the true RR 1.1 per unit time exposure. The impact of censoring depended on exposure prevalence, outcome incidence, and duration of the time-interval that was censored. Conclusions: Censoring may differentially impact estimates of exposure effect in studies of constant, firsttime, and cumulative exposure effects. Researchers should be aware of this when combining data from multiple databases or when comparing drug effects across databases

Risk patterns in drug safety study using relative times by accelerated failure time models when proportional hazards assumption is questionable : An illustrative case study of cancer risk of patients on glucose-lowering therapies

Observational drug safety studies may be susceptible to confounding or protopathic bias. This bias may cause a spurious relationship between drug exposure and adverse side effect when none exists and may lead to unwarranted safety alerts. The spurious relationship may manifest itself through substantially different risk levels between exposure groups at the start of follow-up when exposure is deemed too short to have any plausible biological effect of the drug. The restrictive proportional hazards assumption with its arbitrary choice of baseline hazard function renders the commonly used Cox proportional hazards model of limited use for revealing such potential bias. We demonstrate a fully parametric approach using accelerated failure time models with an illustrative safety study of glucose-lowering therapies and show that its results are comparable against other methods that allow time-varying exposure effects. Our approach includes a wide variety of models that are based on the flexible generalized gamma distribution and allows direct comparisons of estimated hazard functions following different exposure-specific distributions of survival times. This approach lends itself to two alternative metrics, namely relative times and difference in times to event, allowing physicians more ways to communicate patient's prognosis without invoking the concept of risks, which some may find hard to grasp. In our illustrative case study, substantial differences in cancer risks at drug initiation followed by a gradual reduction towards null were found. This evidence is compatible with the presence of protopathic bias, in which undiagnosed symptoms of cancer lead to switches in diabetes medication. Copyright © 2015 John Wiley & Sons, Ltd