Conditional steady-state bounds for a subset of states in Markov chains

The problem of computing bounds on the conditional steady-state probability vector of a subset of states in finite, ergodic discrete-time Markov chains (DTMCs) is considered. An improved algorithm utilizing the strong stochastic (st-)order is given. On standard benchmarks from the literature and other examples, it is shown that the proposed algorithm performs better than the existing one in the strong stochastic sense. Furthermore, in certain cases the conditional steady-state probability vector of the subset under consideration can be obtained exactly. Copyright 2006 ACM

Biopolymer-based membranes associated with osteogenic growth peptide for guided bone regeneration

Barrier membranes for guided bone regeneration (GBR) mainly promote mechanical maintenance of bone defect space and induce osteopromotion. Additionally, biopolymer-based membranes may provide greater bioactivity and biocompatibility due to their similarity to extracellular matrix (ECM).In this study, biopolymers-based membranes from bacterial cellulose (BC) and collagen (COL) associated with osteogenic growth peptide (OGP(10–14)) were evaluated to determine in vitro osteoinductive potential in early osteogenesis; moreover, histological study was performed to evaluate the BC–COL OGP(10–14) membranes on bone healing after GBR in noncritical defects in rat femur. The results showed that the BC–COL and BC–COL OGP(10–14) membranes promoted cell proliferation and alkaline phosphatase activity in osteoblastic cell cultures. However, ECMmineralization was similar between cultures grown on BC OGP(10–14) and BC–COL OGP(10–14) membranes. In vivo results showed that all the membranes tested, including the peptide-free BC membrane, promoted better bone regeneration than control group. Furthermore, the BC–COL OGP(10–14) membranes induced higher radiographic density in the repaired bone than the other groups at 1, 4 and 16 weeks. Histomorpho-metric analyses revealed that the BC–COL OGP(10–14) induced higher percentage of bone tissue in the repaired area at 2 and 4 weeks than others membranes. In general, these biopolymer-based membranes might be potential candidates for bone regeneration applications

Nucleolus: the fascinating nuclear body

Nucleoli are the prominent contrasted structures of the cell nucleus. In the nucleolus, ribosomal RNAs are synthesized, processed and assembled with ribosomal proteins. RNA polymerase I synthesizes the ribosomal RNAs and this activity is cell cycle regulated. The nucleolus reveals the functional organization of the nucleus in which the compartmentation of the different steps of ribosome biogenesis is observed whereas the nucleolar machineries are in permanent exchange with the nucleoplasm and other nuclear bodies. After mitosis, nucleolar assembly is a time and space regulated process controlled by the cell cycle. In addition, by generating a large volume in the nucleus with apparently no RNA polymerase II activity, the nucleolus creates a domain of retention/sequestration of molecules normally active outside the nucleolus. Viruses interact with the nucleolus and recruit nucleolar proteins to facilitate virus replication. The nucleolus is also a sensor of stress due to the redistribution of the ribosomal proteins in the nucleoplasm by nucleolus disruption. The nucleolus plays several crucial functions in the nucleus: in addition to its function as ribosome factory of the cells it is a multifunctional nuclear domain, and nucleolar activity is linked with several pathologies. Perspectives on the evolution of this research area are proposed

Isothermal and cyclic oxidation behaviour of hot-pressed MSi2 compounds (with M = V, Ti, Cr)

International audienceThe oxidation resistance of MSi2 compounds with M = V, Ti, Cr was investigated from 450 to 950 degrees C in air under isothermal and cyclic conditions. Vanadium, chromium and titanium disilicide were not subjected to the pest phenomenon at 650 degrees C over 800 1-h cycles. The results demonstrated very low weight gains regardless of the testing conditions. Oxidation tests were also performed over long duration (1000 h) to identify the oxidation products. The MSi2 compounds were all subjected to the simultaneous oxidation of M and Si despite the formation of a protective silica scale. Increasing the duration of oxidation enhanced the protective properties of the silica scale. Therefore, short-term measurements (by thermogravimetry) did not allow an extrapolation of the MSi2 lifetime. The formation of molten V2O5 induced a higher oxidation rate of VSi2 and delayed the establishment of the protective silica scale compared with CrSi2 and TiSi2

Coaxial Mach–Zehnder Digital Strain Sensor Made from a Tapered Depressed Cladding Fiber

An in-line digital optical sensor was proposed. It was built from a tapered depressed-cladding single-mode fiber and modeled as a coaxial Mach–Zehnder interferometer. The principle of operation of the optical digital sensor is based on the computation of the number of optical power transfer turning points (PTTP) from the transmission data of the component. Biconic tapers with high values of PTTP, high spectral resolution, high extinction ratio, and low insertion loss were modeled, fabricated, and characterized. As a proof of concept, an in-line digital strain sensor was fabricated and characterized. It presents a free spectral range of 1.3 nm, and produced 96 PTTP, at λ0 = 1.55 μm, under stretch of ΔL = 707 µm, therefore producing a digital resolution of 7.4 µm/PTTP. The sensor also produced a quasi-symmetric response to stretch and compression

Assembly and disassembly of the nucleolus during the cell cycle

The nucleolus is a large nuclear domain in which transcription, maturation and assembly of ribosomes take place. In higher eukaryotes, nucleolar organization in three sub-domains reflects the compartmentation of the machineries related to active or inactive transcription of the ribosomal DNA, ribosomal RNA processing and assembly with ribosomal proteins of the two (40S and 60S) ribosomal subunits. The assembly of the nucleoli during telophase/early G1 depends on pre-existing machineries inactivated during prophase (the transcription machinery and RNP processing complexes) and on partially processed 45S rRNAs inherited throughout mitosis. In telophase, the 45S rRNAs nucleate the prenucleolar bodies and order the dynamics of nucleolar assembly. The assembly/disassembly processes of the nucleolus depend on the equilibrium between phosphorylation/dephosphorylation of the transcription machinery and on the RNP processing complexes under the control of the CDK1-cyclin B kinase and PP1 phosphatases. The dynamics of assembly/disassembly of the nucleolus is time and space regulated

Supplementary Material for: Unemployment and Substance Use in Young Adults: Does Educational Attainment Modify the Association?

We studied whether patterns of substance use in relation to unemployment vary depending on educational level. Data come from 1,126 community-based young adults in France (18-35 years of age in 2011) and their parents (TEMPO and GAZEL studies). Tobacco use (≥1 cigarette/day, 22.5% prevalence), nicotine dependence (Fagerström test ≥2, 7.1% prevalence), alcohol use (≥2 units/week, 25.3% prevalence), alcohol abuse (WHO AUDIT ≥7 in women and ≥8 in men, 10.8% prevalence), cannabis use (≥1 time, 16.5% prevalence), and cannabis abuse (CAST ≥2, 5.0% prevalence) were assessed by interview. We conducted logistic regression analyses controlled for inverse probability weights of unemployment, calculated based on demographics, negative life events, health, and juvenile and parental characteristics. Compared to participants who were always employed, those who were unemployed and had no higher education were more likely to smoke tobacco (OR: 2.76, 95% CI: 1.86-4.10), to be nicotine dependent (OR: 5.70, 95% CI: 3.03-10.73), to use cannabis (OR: 2.27, 95% CI: 1.42-3.64), and to abuse cannabis (OR: 3.38, 95% CI: 1.63-7.04). Those who were unemployed and had higher education were especially likely to abuse alcohol (OR: 1.89, 95% CI: 1.16-3.09). Increases in unemployment may impact population levels of substance use, particularly in young adults with low educational attainment