Search results for " Time"

On Approximation of Entropy Solutions for One System of Nonlinear Hyperbolic Conservation Laws with Impulse Source Terms

2010

We study one class of nonlinear fluid dynamic models with impulse source terms. The model consists of a system of two hyperbolic conservation laws: a nonlinear conservation law for the goods density and a linear evolution equation for the processing rate. We consider the case when influx-rates in the second equation take the form of impulse functions. Using the vanishing viscosity method and the so-called principle of fictitious controls, we show that entropy solutions to the original Cauchy problem can be approximated by optimal solutions of special optimization problems.

The selection of serum-independent PC12 cells for a more-reliable manganese cytotoxicity test.

2007

A major issue concerning the protocols of heavy metal cytotoxicity tests with PC12 cells was the hypothesis that serum in the culture medium might sequester the metal, thus altering the results obtained. However, serum withdrawal impairs the viability of PC12 cells themselves, thus impeding cytotoxicity testing in the absence of serum. In this study, we repeatedly selected undifferentiated, totally non-adherent PC12 cells in Petri dishes. Surprisingly, we discovered that these cells could survive and proliferate in serum-free medium. Moreover, features such as NGF-responsiveness, resazurin reduction potential, doubling rate, protein content, and basal caspase-3 enzyme activity, were equiva…

OPETH: Open Source Solution for Real-Time Peri-Event Time Histogram Based on Open Ephys

2019

Single cell electrophysiology remains one of the most widely used approaches of systems neuroscience. Decisions made by the experimenter during electrophysiology recording largely determine recording quality, duration of the project and value of the collected data. Therefore, online feedback aiding these decisions can lower monetary and time investment, and substantially speed up projects as well as allow novel studies otherwise not possible due to prohibitively low throughput. Real-time feedback is especially important in studies that involve optogenetic cell type identification by enabling a systematic search for neurons of interest. However, such tools are scarce and limited to costly co…

Immediate and long-term microshear bond strength of resin-based cements to core build-up materials

2021

Background To evaluate the microshear bond strength (μ-SBS) between resin-based cements and core build-up materials after water storage. Material and methods Cylinders (1x1 mm) of conventional dual-cure resin cement (RelyX ARC, 3M ESPE), universal dual-cure resin cement (RelyX Ultimate, 3M ESPE) or self-adhesive resin cement (RelyX U200, 3M ESPE) were adhered to disks (6x2 mm) made with commercial core build-up materials (Bis-Core, Bisco or LuxaCore Z, DMG) or conventional nanocomposite resin (Filtek Z350 XT, 3M ESPE). The specimens (n=10) were submitted to μ-SBS test using a universal testing machine and fracture pattern analysis at 48 hours or after 9 months of water storage. The data wer…

The Relationship between Gray Matter Quantitative MRI and Disability in Secondary Progressive Multiple Sclerosis

2016

Purpose: In secondary progressive Multiple Sclerosis (SPMS), global neurodegeneration as a driver of disability gains importance in comparison to focal inflammatory processes. However, clinical MRI does not visualize changes of tissue composition outside MS lesions. This quantitative MRI (qMRI) study investigated cortical and deep gray matter (GM) proton density (PD) values and T1 relaxation times to explore their potential to assess neuronal damage and its relationship to clinical disability in SPMS. Materials and Methods: 11 SPMS patients underwent quantitative T1 and PD mapping. Parameter values across the cerebral cortex and deep GM structures were compared with 11 healthy controls, and…

Anaesthetic-related neuroprotection: intravenous or inhalational agents?

2010

In designing the anaesthetic plan for patients undergoing surgery, the choice of anaesthetic agent may often appear irrelevant and the best results obtained by the use of a technique or a drug with which the anaesthesia care provider is familiar. Nevertheless, in those surgical procedures (cardiopulmonary bypass, carotid surgery and cerebral aneurysm surgery) and clinical situations (subarachnoid haemorrhage, stroke, brain trauma and postcardiac arrest resuscitation) where protecting the CNS is a priority, the choice of anaesthetic drug assumes a fundamental role. Treating patients with a neuroprotective agent may be a consideration in improving overall neurological outcome. Therefore, a cl…

2019

Abstract Background In old age, decline in functioning may cause changes in walking ability. Our aim was to study whether older people who report adaptive, maladaptive, or no walking modifications differ in outdoor mobility. Methods Community-dwelling people aged 75–90 years (N = 848) were interviewed at baseline, of whom 761 participated in the 2-year follow-up. Walking modifications were assessed by asking the participants whether they had modified their way of walking 2 km due to their health. Based on the responses, three categories were formed: no walking modifications (reference), adaptive (eg, walking more slowly, using an aid), and maladaptive walking modifications (reduced frequenc…

Effectiveness of local feature selection in ensemble learning for prediction of antimicrobial resistance

2008

In the real world concepts are often not stable but change over time. A typical example of this in the biomedical context is antibiotic resistance, where pathogen sensitivity may change over time as pathogen strains develop resistance to antibiotics that were previously effective. This problem, known as concept drift (CD), complicates the task of learning a robust model. Different ensemble learning (EL) approaches (that instead of learning a single classifier try to learn and maintain a set of classifiers over time) have been shown to perform reasonably well in the presence of concept drift. In this paper we study how much local feature selection (FS) can improve ensemble performance for da…

Is there an environmental Kuznets curve for Spain? Fresh evidence from old data

2012

Abstract The information content of the environmental Kuznets curve (EKC) is subject to change over time and all the empirical modeling work that does not take into account the possible variations and instabilities may fail to explain the variations in the per-capita CO2 and per-capita income relationship. In this paper we consider the possibility that a linear cointegrated regression model with multiple structural changes would provide a better empirical description of the Spanish EKC during the period 1857–2007. Our methodology is based on instability tests recently proposed in Kejriwal and Perron (2008, 2010) as well as on cointegration tests developed in Arai and Kurozumi (2007) and Kej…

Aggregate Behavior and Microdata

2004

Abstract It is shown how one can effectively use microdata in modelling the change over time in an aggregate (e.g. mean consumption expenditure) of a large and heterogeneous population. The starting point of our aggregation analysis is a specification of explanatory variables on the micro-level. Typically, some of these explanatory variables are observable and others are unobservable. Based on certain hypotheses on the evolution over time of the joint distributions across the population of these explanatory variables we derive a decomposition of the change in the aggregate which allows a partial analysis: to isolate and to quantify the effect of a change in the observable explanatory variab…