7,892 research outputs found
q-Differential equations for q-classical polynomials and q-Jacobi-Stirling numbers
No full textWe introduce, characterise and provide a combinatorial interpretation for the so-called q-Jacobi–Stirling numbers.
This study is motivated by their key role in the (reciprocal) expansion of any power of a second order
q-differential operator having the q-classical polynomials as eigenfunctions in terms of other even order operators,
which we explicitly construct in this work. The results here obtained can be viewed as the q-version of
those given by Everitt et al. and by the first author, whilst the combinatorics of this new set of numbers is a
q-version of the Jacobi–Stirling numbers given by Gelineau and the second author
P53 functional abnormality in mesenchymal stem cells promotes osteosarcoma development
No full textIt has been shown that p53 has a critical role in the differentiation and functionality of various multipotent progenitor cells. P53 mutations can lead to genome instability and subsequent functional alterations and aberrant transformation of mesenchymal stem cells (MSCs). The significance of p53 in safeguarding our body from developing osteosarcoma (OS) is well recognized. During bone remodeling, p53 has a key role in negatively regulating key factors orchestrating the early stages of osteogenic differentiation of MSCs. Interestingly, changes in the p53 status can compromise bone homeostasis and affect the tumor microenvironment. This review aims to provide a unique opportunity to study the p53 function in MSCs and OS. In the context of loss of function of p53, we provide a model for two sources of OS: MSCs as progenitor cells of osteoblasts and bone tumor microenvironment components. Standing at the bone remodeling point of view, in this review we will first explain the determinant function of p53 in OS development. We will then summarize the role of p53 in monitoring MSC fidelity and in regulating MSC differentiation programs during osteogenesis. Finally, we will discuss the importance of loss of p53 function in tissue microenvironment. We expect that the information provided herein could lead to better understanding and treatment of OS
Tobin's Q and Financial Policy
No full textRecent research in macroeconomics has emphasized the importance of linking the financial and real sectors and the need for working with optimizing models. Tobin’s Q model of investment would appear to provide a framework that can satisfy these two criteria. In contrast to the original presentation of the Q model, the formal development has not recognized that the firm actively participates in a number of financial markets; in this broader context, we show that Q is likely to be an uninformative and possibly misleading signal for investment expenditures . We then endeavor to turn this negative theoretical result to positive advantage in resolving a number of empirical problems with Q models, but the modifications dictated by the theory receive little support from the data.
Loss of p53 in mesenchymal stem cells promotes alteration of bone remodeling through negative regulation of osteoprotegerin
No full textp53 plays a pivotal role in controlling the differentiation of mesenchymal stem cells (MSCs) by regulating genes involved in cell cycle and early steps of differentiation process. In the context of osteogenic differentiation of MSCs and bone homeostasis, the osteoprotegerin/receptor activator of NF-kappa B ligand/receptor activator of NF-kappa B (OPG/RANKL/RANK) axis is a critical signaling pathway. The absence or loss of function of p53 has been implicated in aberrant osteogenic differentiation of MSCs that results in higher bone formation versus erosion, leading to an unbalanced bone remodeling. Here, we show by microCT that mice with p53 deletion systemically or specifically in mesenchymal cells possess significantly higher bone density than their respective littermate controls. There is a negative correlation between p53 and OPG both in vivo by analysis of serum from p53(+/+), p53(+/-), and p53(-/-)mice and in vitro by p53 knockdown and ChIP assay in MSCs. Notably, high expression ofOpgor its combination with low level of p53 are prominent features in clinical cancer lesion of osteosarcoma and prostate cancer respectively, which correlate with poor survival. Intra-bone marrow injection of prostate cancer cells, together with androgen can suppress p53 expression and enhance localOpgexpression, leading to an enhancement of bone density. Our results support the notion that MSCs, as osteoblast progenitor cells and one major component of bone microenvironment, represent a cellular source of OPG, whose amount is regulated by the p53 status. It also highlights a key role for the p53-OPG axis in regulating the cancer associated bone remodeling
Power concave operators and representation of p-convex and q-concave Banach lattices
No full text[EN] As a consequence of the analysis of the class of (p, q)-power concave operators, we prove a general representation theorem for p-convex and q-concave Banach lattices as spaces of integrable functions with respect to vector measures. This result culminates a series of representation theorems for Banach lattices using vector measures that have been obtained in the last twenty years.The first author gratefully acknowledges the support of the Ministerio de Economia y Competitividad (project #MTM2012-36732-C03-03) and the Junta de Andalucia (projects FQM-262 and FQM-7276), Spain. The second author acknowledges with thanks the support of the Ministerio de Economia y Competitividad (project # MTM2012-36740-C02-02), Spain.Delgado Garrido, O.; Sánchez Pérez, EA. (2017). Power concave operators and representation of p-convex and q-concave Banach lattices. Journal of Operator Theory. 77(2):261-286. https://doi.org/10.7900/jot.2016feb21.2137S26128677
Factorization of (q, p)-summing polynomials through Lorentz spaces
No full text[EN] We present a vector valued duality between factorable (q,p)-summing polynomials and (q,p)-summing linear operators on symmetric tensor products of Banach spaces. Several applications are provided. First, we prove a polynomial characterization of cotype of Banach spaces. We also give a variant of Pisier's factorization through Lorentz spaces of factorable (q,p)-summing polynomials from C(K)-spaces. Finally, we show a coincidence result for (q,p)-concave polynomials.(c) 2016 Elsevier Inc. All rights reserved.The first named author was supported by The National Science Centre (NCN), Poland, project no. 2011/01/B/ST1/06243. The second and third authors were supported by the Ministerio de Economia y Competitividad (Spain) under project MTM2016-77054-C2-1-P.Mastylo, M.; Rueda, P.; Sánchez Pérez, EA. (2017). Factorization of (q, p)-summing polynomials through Lorentz spaces. Journal of Mathematical Analysis and Applications. 449(1):195-206. https://doi.org/10.1016/j.jmaa.2016.12.005S195206449
MULTIFRACTAL q RÉNYI DIMENSIONS OF POLISH SPACES FOR q < 1
No full text In earlier work the second author investigated the multifractal q Rényi dimensions of Polish spaces for q ≥ 1. In this paper we complement those results by investigating the multifractal q Rényi dimensions of Polish spaces for q < 1. </jats:p
A Comparative Assessment of Answer Quality on Four Question Answering Sites
No full textQuestion answering (Q&A) sites, where communities of volunteers answer questions, may provide faster, cheaper, and better services than traditional institutions. However, like other Web 2.0 platforms, user-created content raises concerns about information quality. At the same time, Q&A sites may provide answers of different quality because they have different communities and technological platforms. This paper compares answer quality on four Q&A sites: Askville, WikiAnswers, Wikipedia Reference Desk, and Yahoo! Answers. Findings indicate that: 1) the use of similar collaborative processes on these sites results in a wide range of outcomes. Significant differences in answer accuracy, completeness, and verifiability were found; 2) answer multiplication does not always result in better information. Answer multiplication yields more complete and verifiable answers but does not result in higher accuracy levels; and 3) a Q&A site’s popularity does not correlate with its answer quality, on all three measures
Metabolic profiling and population screening of analgesic usage in nuclear magnetic resonance spectroscopy-based large-scale epidemiologic studies
No full textThe application of a 1H nuclear magnetic resonance (NMR) spectroscopy-based screening method for determining the use of two widely available analgesics (acetaminophen and ibuprofen) in epidemiologic studies has been investigated. We used samples and data from the cross-sectional INTERMAP Study involving participants from Japan (n = 1145), China (n = 839), U.K. (n = 501), and the U.S. (n = 2195). An orthogonal projection to latent structures discriminant analysis (OPLS-DA) algorithm with an incorporated Monte Carlo resampling function was applied to the NMR data set to determine which spectra contained analgesic metabolites. OPLS-DA preprocessing parameters (normalization, bin width, scaling, and input parameters) were assessed systematically to identify an optimal acetaminophen prediction model. Subsets of INTERMAP spectra were examined to verify and validate the presence/absence of acetaminophen/ibuprofen based on known chemical shift and coupling patterns. The optimized and validated acetaminophen model correctly predicted 98.2%, and the ibuprofen model correctly predicted 99.0% of the urine specimens containing these drug metabolites. The acetaminophen and ibuprofen models were subsequently used to predict the presence/absence of these drug metabolites for the remaining INTERMAP specimens. The acetaminophen model identified 415 out of 8436 spectra as containing acetaminophen metabolite signals while the ibuprofen model identified 245 out of 8604 spectra as containing ibuprofen metabolite signals from the global data set after excluding samples used to construct the prediction models. The NMR-based metabolic screening strategy provides a new objective approach for evaluation of self-reported medication data and is extendable to other aspects of population xenometabolome profiling
Effect of Retained Austenite on the Corrosion Behaviour of Q&P Processed Martensitic Stainless Steels
No full textThe fuel consumption of cars has become an important issue in the development of new materials and. These developments resulted in the generation of new grades of steel for the automotive industry. In particular, new advanced high strength steels (AHSS) have been developed for the automotive industry to lower fuel consumption (with weight reduction) by combining strength with formability. Especially, quenching and partitioning (Q&P) steels from 3rd generation AHSS can exhibit significant strength and ductility balance by combining martensite with retained austenite. Recently, there has been a new interest in applying the Q&P treatment to stainless steels, in particular martensitic stainless steel. For the automotive industry, the development in Q&P treated martensitic stainless steel can be a game-changer. The mechanical properties of Q&P treated commercial martensitic stainless steels have been widely researched. Unlike mechanical behaviour, the corrosion behaviour of Q&P treated martensitic stainless steel has not been investigated deeply. The effect of environmental factors or the effect of microstructure on the corrosion performance of Q&P processed martensitic stainless steel needs to be studied. This master thesis aims to identify the effect of microstructural constituents (retained austenite, primary and fresh martensite) on the corrosion response of Q&P treated martensitic stainless steels. To this end, an experimental approach is taken for this project. This work aims to create a relationship between heat treatment, microstructure, and the resulting corrosion properties. As an experimental path, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and Mott-Schottky experiments were carried out in 3.5 wt.% NaCl solution to reveal the corrosion response and passive film properties of the Q&P microstructures. In addition, X-ray photoelectron spectroscopy (XPS) was performed to analyze the chemical composition and fractions of oxide layers in the passive layer. Results demonstrate a phase dependency for the corrosion performance of Q&P treated martensitic stainless steels.Materials Science and Engineerin
- …
