4,156 research outputs found
Statistical Learning in Wasserstein Space
We seek a generalization of regression and principle component analysis (PCA) in a metric space where data points are distributions metrized by the Wasserstein metric. We recast these analyses as multimarginal optimal transport problems. The particular formulation allows efficient computation, ensures existence of optimal solutions, and admits a probabilistic interpretation over the space of paths (line segments). Application of the theory to the interpolation of empirical distributions, images, power spectra, as well as assessing uncertainty in experimental designs, is envisioned
On the effects of exothermicity and endothermicity upon the temperature fields in a partially-filled porous channel
Forced convection of heat in a two-dimensional channel, partially filled by a porous insert is considered. This system is assumed under fully developed conditions and constant wall heat flux. Further, the fluid and solid phases can feature internal heat generation (exothermicity) and consumption (endothermicity). Analytical solutions are developed for the solid and fluid temperature fields by applying local thermal non-equilibrium (LTNE) conditions and the Darcy-Brinkman model of momentum transport. Two existing interface models (Models A and B) are employed to describe the thermal boundary conditions at the porous-fluid interface. The developed solutions for the temperature fields are compared to those found by applying the local thermal equilibrium (LTE) assumption and, therefore, the validity of the LTE is examined. This is done for a wide range of pertinent parameters including Biot number, conductivity ratio, Darcy number and thickness of the porous insert. It is found that the thermal behaviour of the investigated partially filled system is influenced by the heat sources in both solid and fluid phase. It is further shown that the LTE approach remains an acceptable assumption only for some specific regions of the parametric space. Furthermore, the occurrence of temperature gradient bifurcation on the surface of the porous-fluid interface is examined. It is demonstrated that this effect is highly sensitive to the intensity of the energy sources
Numerical Modelling for Process Investigation of a Single Coal Particle Combustion and Gasification
Combustion and Gasification are commercial
processes of coal utilization, and therefore continuous
improvement is needed for these applications. The difference
between these processes is the reaction mechanism, in the case
of combustion the reaction products are CO2 and H2O, whereas
in the case of gasification the products are CO, H2 and CH4. In
order to investigate these processes further, a single coal particle
model has been developed. The definition of the chemical
reactions for each process is key for model development. The
developed numerical model simulation uses CFD
(Computational Fluid Dynamic) techniques with an Eddy Break
Up (EBU) model and a kinetics parameter for controlling the
process reaction. The combustion model has been validated and
extended to model the gasification process by inclusion of an
additional chemical reaction. Finally, it is shown that the single
coal particle model could describe single coal particle
combustion and gasification. From the result, the difference
between single coal particle combustion and gasification can
clearly be seen. This simulation model can be considered for
further investigation of coal combustion and gasification
application processes
Three-dimensional numerical simulations of free convection in a layered porous enclosure
Three-dimensional numerical simulations are carried out for the study of free
convection in a layered porous enclosure heated from below and cooled from the
top. The system is defined as a cubic porous enclosure comprising three layers,
of which the external ones share constant physical properties and the internal
layer is allowed to vary in both permeability and thermal conductivity. The
model is based on Darcy's law and the Boussinesq approximation. A parametric
study to evaluate the sensitivity of the Nusselt number to a decrease in the
permeability of the internal layer shows that strong permeability contrasts are
required to observe an appreciable drop in the Nusselt number. If additionally
the thickness of the internal layer is increased, a further decrease in the Nusselt
number is observed as long as the convective modes remain the same, if the
convective modes change the Nusselt number may increase. Decreasing the
thermal conductivity of the middle layer causes first an increment in the Nusselt
number and then a drop. On the other hand, the Nusselt number decreases in
an approximately linear trend when the thermal conductivity of the layer is
increased
Polarization control of single photon quantum orbital angular momentum states
The orbital angular momentum of photons, being defined in an infinitely
dimensional discrete Hilbert space, offers a promising resource for
high-dimensional quantum information protocols in quantum optics. The biggest
obstacle to its wider use is presently represented by the limited set of tools
available for its control and manipulation. Here, we introduce and test
experimentally a series of simple optical schemes for the coherent transfer of
quantum information from the polarization to the orbital angular momentum of
single photons and vice versa. All our schemes exploit a newly developed
optical device, the so-called "q-plate", which enables the manipulation of the
photon orbital angular momentum driven by the polarization degree of freedom.
By stacking several q-plates in a suitable sequence, one can also access to
higher-order angular momentum subspaces. In particular, we demonstrate the
control of the orbital angular momentum degree of freedom within the
subspaces of and per photon. Our experiments prove
that these schemes are reliable, efficient and have a high fidelity.Comment: 9 pages, 8 figure
Facilitators and barriers of adaptation to diabetes: experiences of Iranian patients
Background: Diabetes mellitus is one of the most challenging and burdensome chronic diseases of the 21st century and More than 1% of the Iranian urban population older than 20 years develops Type 2 diabetes each year. Living with diabetes mellitus has been described as a dynamic personal transitional adaptation, based on restructuring of the illness perceived experience and management of the self. Adaptation to Type 2 Diabetes mellitus is an integral part of diabetes care.This study explored the experiences of facilitators and barriers adaptation to Type 2 Diabetes by Iranian patients.Methods: This study was conducted by using qualitative content analysis. Data were collected via in-depth, semi-structured and face to face interviews with 15 patients with type2 diabetes.Results: Three themes emerged from collected data, including a) individual context with Beliefs, personal background, and previous experience subthemes. b) supportive system with Family, Society and Health organizations subthemes and c) self-comparison with comparison with other diabetes and comparison with other diseases subthemes.Conclusions: Identifying and managing Facilitators and Barriers adaptation to Type 2 Diabetes mellitus are an integral part of diabetes care. This study provides a better understanding of the factors from perspective of patients and it can be utilized by health care providers to adapt their health care and education contents to better meet the needs of people with diabetes. © 2014 Karimi Moonaghi et al.; licensee BioMed Central Ltd
Struggling towards diagnosis: Experiences of Iranian diabetes
Background: Healthcare-seeking behavior is one of the factors determining the uptake and outcome of healthcare. However, few studies have discussed how and why diabetics seek healthcare assistance before meeting a physician. Objectives: In this study, we explored the subjective experiences of healthcare-seeking behavior among Iranian patients with type 2 diabetes mellitus. Patients and Methods: A qualitative approach was adopted using a conventional content analysis of semi-structured interviews carried out in the Diabetes Association in Tabriz (Iran) with 15 participants suffering from type 2 diabetes. Participants were recruited by the purposeful sampling method. Results: Five themes emerged from the study: 1) warning by physical signs; 2) personal processing; 3) self-remedy and its outcomes; 4) seeking information, and; 5) diagnosis and verification of information by healthcare staff. Conclusions: Individual social context plays an important role in the decision-making process when seeking healthcare for diabetes. The results of this study can be utilized by healthcare providers to facilitate interventions to increase diabetics' active involvement in their healthcare, and encourage a wider knowledge of its symptoms and outcomes to facilitate appropriate healthcare-seeking and service use. © 2014, Iranian Red Crescent Medical Journal
Expression of LDL receptor-related proteins (LRPs) in common solid malignancies correlates with patient survival
LDL receptor-related proteins (LRPs) are transmembrane receptors involved in endocytosis, cell-signaling, and trafficking of other cellular proteins. Considerable work has focused on LRPs in the fields of vascular biology and neurobiology. How these receptors affect cancer progression in humans remains largely unknown. Herein, we mined provisional data-bases in The Cancer Genome Atlas (TCGA) to compare expression of thirteen LRPs in ten common solid malignancies in patients. Our first goal was to determine the abundance of LRP mRNAs in each type of cancer. Our second goal was to determine whether expression of LRPs is associated with improved or worsened patient survival. In total, data from 4,629 patients were mined. In nine of ten cancers studied, the most abundantly expressed LRP was LRP1; however, a correlation between LRP1 mRNA expression and patient survival was observed only in bladder urothelial carcinoma. In this malignancy, high levels of LRP1 mRNA were associated with worsened patient survival. High levels of LDL receptor (LDLR) mRNA were associated with decreased patient survival in pancreatic adenocarcinoma. High levels of LRP10 mRNA were associated with decreased patient survival in hepatocellular carcinoma, lung adenocarcinoma, and pancreatic adenocarcinoma. LRP2 was the only LRP for which high levels of mRNA expression correlated with improved patient survival. This correlation was observed in renal clear cell carcinoma. Insights into LRP gene expression in human cancers and their effects on patient survival should guide future research
Rapid Synthesis of 2-Substituted-2,3-dihydro-4(1H)-quinazolinones using Boric Acid or Sodium Dihydrogen Phosphate under Solvent-Free Conditions
Two efficient and convenient methods have been described for synthesis of 2-substituted-2,3-dihydro-4(1H)-quinazolinone derivatives by one-pot condensation of 2-anthranilamide with aldehydes or ketones in the presence of a catalytic amount of boric acid or sodium dihydrogen phosphate under solvent-free conditions. The attractive features of these processes are short reaction times, easy isolation of products, excellent yields and an environmental friendly procedure.Keywords: Dihydroquinazolinones, boric acid, sodium dihydrogen phosphate, 2-anthranilamide, solvent-free synthesi
- …