3,164 research outputs found
Analysis of SPDEs Arising in Path Sampling Part I: The Gaussian Case
In many applications it is important to be able to sample paths of SDEs
conditional on observations of various kinds. This paper studies SPDEs which
solve such sampling problems. The SPDE may be viewed as an infinite dimensional
analogue of the Langevin SDE used in finite dimensional sampling. Here the
theory is developed for conditioned Gaussian processes for which the resulting
SPDE is linear. Applications include the Kalman-Bucy filter/smoother. A
companion paper studies the nonlinear case, building on the linear analysis
provided here
Evaluating Equating Transformations in IRT Observed-Score and Kernel Equating Methods
Test equating is a statistical procedure to ensure that scores from different test forms can be used interchangeably. There are several methodologies available to perform equating, some of which are based on the Classical Test Theory (CTT) framework and others are based on the Item Response Theory (IRT) framework. This article compares equating transformations originated from three different frameworks, namely IRT Observed-Score Equating (IRTOSE), Kernel Equating (KE), and IRT Kernel Equating (IRTKE). The comparisons were made under different data-generating scenarios, which include the development of a novel data-generation procedure that allows the simulation of test data without relying on IRT parameters while still providing control over some test score properties such as distribution skewness and item difficulty. Our results suggest that IRT methods tend to provide better results than KE even when the data are not generated from IRT processes. KE might be able to provide satisfactory results if a proper pre-smoothing solution can be found, while also being much faster than IRT methods. For daily applications, we recommend observing the sensibility of the results to the equating method, minding the importance of good model fit and meeting the assumptions of the framework
Dynamic MR imaging as a predictor of prognosis in breast cancer
Contrast-enhanced MR imaging (CE-MRI) has become a widely accepted complementary method for diagnosing breast cancer. It has been suggested for evaluating patients with breast implants, patients at risk of tumour multifocality or recurrence, search for occult primary cancer in presence of axillary metastasis and monitoring the effect of preoperative chemotherapy. The clinical usefulness of MR imaging in patients with increased genetic risk of breast cancer is still under investigation. There is scientific evidence to support the hypothesis that CE-MRI may carry the prognostic significance of angiogenesis, and one of the future indications of this method can be the prognostic evaluation of breast cancer patients by the functional mapping of the angiogenic activity of tumours. On the basis of the promising results of recent reports, further large-scale studies are needed to evaluate the impact of MR parameters on long term overall survival of patients with breast cancer.</jats:p
STUDIES ON LABILE DEOXYCYTIDYLATE HYDROXYMETHYLASES FROM ESCHERICHIA COLI B INFECTED WITH TEMPERATURE-SENSITIVE MUTANTS OF BACTERIOPHAGE T4
Ion counting efficiencies at the IGISOL facility
At the IGISOL-JYFLTRAP facility, fission mass yields can be studied at high
precision. Fission fragments from a U target are passing through a Ni foil and
entering a gas filled chamber. The collected fragments are guided through a
mass separator to a Penning trap where their masses are identified. This
simulation work focuses on how different fission fragment properties (mass,
charge and energy) affect the stopping efficiency in the gas cell. In addition,
different experimental parameters are varied (e. g. U and Ni thickness and He
gas pressure) to study their impact on the stopping efficiency. The simulations
were performed using the Geant4 package and the SRIM code. The main results
suggest a small variation in the stopping efficiency as a function of mass,
charge and kinetic energy. It is predicted that heavy fragments are stopped
about 9% less efficiently than the light fragments. However it was found that
the properties of the U, Ni and the He gas influences this behavior. Hence it
could be possible to optimize the efficiency.Comment: 52 pages, 44 figure
Stimulating the Neurotrophic and Angiogenic Properties of Human Adipose-Derived Stem Cells Enhances Nerve Repair
How to define (net) zero greenhouse gas emissions buildings: The results of an international survey as part of IEA EBC annex 72
The concept of (net) zero greenhouse gas (GHG) emission(s) buildings is gaining wide international attention and is considered to be the main pathway for achieving climate neutrality targets in the built environment. However, there is an increasing plethora of differing terms, definitions, and approaches emerging worldwide. To understand the current progress of the ongoing discussion, this study provides an overview of terms, definitions, and key features from a review of 35 building assessment approaches. The investigation identified that 13 voluntary frameworks from 11 countries are particularly characterised by net zero-carbon/GHG emissions performance targets, which are then subject to a more detailed analysis. The review was organised in the context of the project IEA EBC Annex 72 on âAssessing Life Cycle Related Environmental Impacts Caused by Buildingsâ, which involves researchers from over 25 countries worldwide.
In the current dynamic political surroundings and ongoing scientific debate, only an initial overview of this topic can be presented. However, providing typologies and fostering transparency would be instrumental in delivering clarity, limiting misunderstanding, and avoiding potential greenwashing. To this end, this article categorises the most critical methodological optionsâi.e., system boundaries for both operational and embodied GHG emissions, the type of GHG emission factor for electricity use, the approach to the âtimeâ aspect, and the possibilities of GHG emission compensationâinto a comprehensive framework for clarifying or setting (net) zero GHG emission building definitions in a more systematic way.
The article concludes that although variations in the existing approaches will continue to exist, certain minimum directions should be considered for the future development of harmonised (net) zero GHG emissions building frameworks. As a minimum, it is recommended to extend the usual scope of the operational energy use balance. At the same time, minimum requirements must also be set for embodied GHG emissions even if they are not considered in the carbon/GHG emissions balance
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