373 research outputs found
Simulation approach for assessing the performance of the ÎłEWMA control chart
i) Purpose: The purpose of this paper is to evaluate the performance of a modified EWMA control chart (EWMA control chart), which considers data distribution and incorporate its correlation structure, simulating in-control and out-of-control processes and to select an adequate value for smoothing parameter with these conditions. ii) Design/methodology/approach:
This paper is based on a simulation approach using the methodology for evaluating statistical methods proposed by Morris et al. (2019). Data were generated from a simulation considering two factors that associated with data: (1) quality variable distribution skewness as an indicator of quality variable distribution; (2) the autocorrelation structure for type of relationship between the observations and modeled by AR(1). In addition, one factor associated with the process was considered, (1) the shift in the process mean. In the following step, when the chart control is modeled, the fourth factor intervenes. This factor is a smoothing parameter. Finally, three indicators defined from the Run Length are used to evaluate ÎłEWMA control chart performance this factors and their interactions. iii) Findings: Interaction analysis for four factor evidence that the modeling and selection of parameters is different for out-of-control and in-control processes therefore the considerations and parameters selected for each case must be carefully analyzed. For out-of-control processes, it is better to preserve the original features of the distribution (mean and variance) for the calculation of the control limits. It makes sense that highly autocorrelated observations require smaller smoothing parameter since the correlation structure enables the preservation of relevant information in past data. iv) Originality/value: The EWMA control chart there has advantages because it gathers, in single chart control: the process and modelling characteristics, and data structure process. Although there are other proposals for modified EWMA, none of them simultaneously analyze the four factors nor their interactions. The proposed EWMA allows setting the appropriate smoothing parameter when these three factors are considered
Cellular EXchange Imaging (CEXI): Evaluation of a diffusion model including water exchange in cells using numerical phantoms of permeable spheres
Purpose: Biophysical models of diffusion MRI have been developed to
characterize microstructure in various tissues, but existing models are not
suitable for tissue composed of permeable spherical cells. In this study we
introduce Cellular Exchange Imaging (CEXI), a model tailored for permeable
spherical cells, and compares its performance to a related Ball \& Sphere (BS)
model that neglects permeability. Methods: We generated DW-MRI signals using
Monte-Carlo simulations with a PGSE sequence in numerical substrates made of
spherical cells and their extracellular space for a range of membrane
permeability. From these signals, the properties of the substrates were
inferred using both BS and CEXI models. Results: CEXI outperformed the
impermeable model by providing more stable estimates cell size and
intracellular volume fraction that were diffusion time-independent. Notably,
CEXI accurately estimated the exchange time for low to moderate permeability
levels previously reported in other studies (). However, in
highly permeable substrates (), the estimated parameters were
less stable, particularly the diffusion coefficients. Conclusion: This study
highlights the importance of modeling the exchange time to accurately quantify
microstructure properties in permeable cellular substrates. Future studies
should evaluate CEXI in clinical applications such as lymph nodes, investigate
exchange time as a potential biomarker of tumor severity, and develop more
appropriate tissue models that account for anisotropic diffusion and highly
permeable membranes.Comment: 7 figures, 2 tables, 21 pages, under revie
Monocapas de ĂĄcidos grasos. III. Ăcidos palmĂtico, lĂĄurico y oleico sobre disoluciones acuosas que contienen solutos con grupos funcionales alcohĂłlicos
The influence exerted by the length or the insaturation of acyl chain on characteristics of fatty acid monolayers spread on aqueous solutions containing ethanol, glycerol, glucose or sucrose, is studied using a Langmuir type surface balance.
The monolayer stability is function of acyl chain length and presence of insaturation. Generally, the factors decreasing monolayer stability can help transformations towards configurations with more expanded structures.Se ha estudiado la influencia que ejercen la longitud y la insaturaciĂłn de la cadena acĂlica sobre las caracterĂsticas de las monocapas de ĂĄcidos grasos esparcidas sobre medios acuosos que contienen etanol, glicerina, glucosa o sacarosa, utilizando una balanza de superficie de tipo Langmuir.
La estabilidad de la monocapa es funciĂłn de la longitud de la cadena acĂlica y de la presencia de insaturaciĂłn. En general, los mismos factores que disminuyen la estabilidad de la monocapa pueden favorecer las transiciones hacia configuraciones con estructuras mĂĄs expandidas
String Theory and Quantum Chromodynamics
I review recent progress on the connection between string theory and quantum
chromodynamics in the context of the gauge/gravity duality. Emphasis is placed
on conciseness and conceptual aspects rather than on technical details. Topics
covered include the large-Nc limit of gauge theories, the gravitational
description of gauge theory thermodynamics and hydrodynamics, and
confinement/deconfinement thermal phase transitions.Comment: 38 pages, 24 figures. Lectures given at the RTN Winter School on
"Strings, Supergravity and Gauge Theories" at CERN on January 15-19, 200
Amplified and Homozygously Deleted Genes in Glioblastoma: Impact on Gene Expression Levels
BACKGROUND:
Glioblastoma multiforme (GBM) displays multiple amplicons and homozygous deletions that involve relevant pathogenic genes and other genes whose role remains unknown.
METHODOLOGY:
Single-nucleotide polymorphism (SNP)-arrays were used to determine the frequency of recurrent amplicons and homozygous deletions in GBM (n = 46), and to evaluate the impact of copy number alterations (CNA) on mRNA levels of the genes involved.
PRINCIPAL FINDINGS:
Recurrent amplicons were detected for chromosomes 7 (50%), 12 (22%), 1 (11%), 4 (9%), 11 (4%), and 17 (4%), whereas homozygous deletions involved chromosomes 9p21 (52%) and 10q (22%). Most genes that displayed a high correlation between DNA CNA and mRNA levels were coded in the amplified chromosomes. For some amplicons the impact of DNA CNA on mRNA expression was restricted to a single gene (e.g., EGFR at 7p11.2), while for others it involved multiple genes (e.g., 11 and 5 genes at 12q14.1-q15 and 4q12, respectively). Despite homozygous del(9p21) and del(10q23.31) included multiple genes, association between these DNA CNA and RNA expression was restricted to the MTAP gene.
CONCLUSIONS:
Overall, our results showed a high frequency of amplicons and homozygous deletions in GBM with variable impact on the expression of the genes involved, and they contributed to the identification of other potentially relevant genes
Biopolymer-based structuring of liquid oil into soft solids and oleogels using water-continuous emulsions as templates
Physical trapping of a hydrophobic liquid oil in a matrix of water-soluble biopolymers was achieved using a facile two-step process by first formulating a surfactant-free oil-in-water emulsion stabilized by biopolymers (a protein and a polysaccharide) followed by complete removal of the water phase (by either high- or low-temperature drying of the emulsion) resulting in structured solid systems containing a high concentration of liquid oil (above 97 wt %). The microstructure of these systems was revealed by confocal and cryo-scanning electron microscopy, and the effect of biopolymer concentrations on the consistency of emulsions as well as the dried product was evaluated using a combination of small-amplitude oscillatory shear rheometry and large deformation fracture studies. The oleogel prepared by shearing the dried product showed a high gel strength as well as a certain degree of thixotropic recovery even at high temperatures. Moreover, the reversibility of the process was demonstrated by shearing the dried product in the presence of water to obtain reconstituted emulsions with rheological properties comparable to those of the fresh emulsion
Behavior and Impact of Zirconium in the SoilâPlant System: Plant Uptake and Phytotoxicity
Because of the large number of sites they pollute, toxic metals that contaminate terrestrial ecosystems are increasingly of environmental and sanitary concern (Uzu et al. 2010, 2011; Shahid et al. 2011a, b, 2012a). Among such metals is zirconium (Zr), which has the atomic number 40 and is a transition metal that resembles titanium in physical and chemical properties (Zaccone et al. 2008). Zr is widely used in many chemical industry processes and in nuclear reactors (Sandoval et al. 2011; Kamal et al. 2011), owing to its useful properties like hardness, corrosion-resistance and permeable to neutrons (Mushtaq 2012). Hence, the recent increased use of Zr by industry, and the occurrence of the Chernobyl and Fukashima catastrophe have enhanced environmental levels in soil and waters (Yirchenko and Agapkina 1993; Mosulishvili et al. 1994 ; Kruglov et al. 1996)
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