Hierarchical Bayes Estimation of Reliability Indexes of Cold Standby Series System under General Progressive Type II Censoring Scheme

In this paper, hierarchical Bayes approach is presented for estimation and prediction of reliability indexes and remaining lifetimes of a cold standby series system under general progressive Type II censoring scheme. A simulation study has been carried out for comparison purpose. The study will help reliability engineers in various industrial series system setups

Preference of Estimation Approach for Rayleigh Progressive Type II Data

This paper compare the performance of the empirical Bayes and generalized maximum likelihood estimation approaches in context of progressively Type II censored data from one parameter Rayleigh distribution. The generalized maximum likelihood and empirical Bayes estimates of scale parameter, reliability function, and failure rate function are compared using risk efficiency criterion. The empirical Bayes estimates are considered with respect to squared error loss function. The wind speed data is presented to illustrate the proposed estimation approaches, and an extensive Monte Carlo simulated study is done to compare the empirical Bayes and Generalized maximum likelihood estimates. The study indicates that the empirical Bayesian approach using squared error loss function is preferable than the generalized maximum likelihood approach for the estimation of reliability performances. Keywords: Progressively Type II censored samples, generalized maximum likelihood estimation, squared error loss function, empirical Bayes estimation, Risk efficiency, Monte Carlo simulation.

Reaction norm analysis reveals rapid shifts toward delayed maturation in harvested Lake Erie yellow perch (Perca flavescens )

Harvested marine fish stocks often show a rapid and substantial decline in the age and size at maturation. Such changes can arise from multiple processes including fisheries‐induced evolution, phenotypic plasticity, and responses to environmental factors other than harvest. The relative importance of these processes could differ systematically between marine and freshwater systems. We tested for temporal shifts in the mean and within‐cohort variability of age‐ and size‐based maturation probabilities of female yellow perch (Perca flavescens Mitchill) from four management units (MUs) in Lake Erie. Lake Erie yellow perch have been commercially harvested for more than a century, and age and size at maturation have varied since sampling began in the 1980s. Our analysis compared probabilistic maturation reaction norms (PMRNs) for cohorts when abundance was lower and harvest higher (1993–1998) to cohorts when abundance was higher and harvest lower (2005–2010). PMRNs have been used in previous studies to detect signs of evolutionary change in response to harvest. Maturation size threshold increased between the early and late cohorts, and the increases were statistically significant for the youngest age in the western MU1 and for older ages in the eastern MU3. Maturation envelope widths, a measure of the variability in maturation among individuals in a cohort, also increased between early and late cohorts in the western MUs where harvest was highest. The highest rates of change in size at maturation for a given age were as large or larger than rates reported for harvested marine fishes where declines in age and size at maturation have been observed. Contrary to the general observation of earlier maturation evolving in harvested stocks, female yellow perch in Lake Erie may be rapidly evolving delayed maturation since harvest was relaxed in the late 1990s, providing a rare example of possible evolutionary recovery

Persistent Homology Over Directed Acyclic Graphs

We define persistent homology groups over any set of spaces which have inclusions defined so that the corresponding directed graph between the spaces is acyclic, as well as along any subgraph of this directed graph. This method simultaneously generalizes standard persistent homology, zigzag persistence and multidimensional persistence to arbitrary directed acyclic graphs, and it also allows the study of more general families of topological spaces or point-cloud data. We give an algorithm to compute the persistent homology groups simultaneously for all subgraphs which contain a single source and a single sink in $O(n^4)$ arithmetic operations, where $n$ is the number of vertices in the graph. We then demonstrate as an application of these tools a method to overlay two distinct filtrations of the same underlying space, which allows us to detect the most significant barcodes using considerably fewer points than standard persistence.Comment: Revised versio

A Tale of Four Stories: Soil Ecology, Theory, Evolution and the Publication System

International audienceBACKGROUND: Soil ecology has produced a huge corpus of results on relations between soil organisms, ecosystem processes controlled by these organisms and links between belowground and aboveground processes. However, some soil scientists think that soil ecology is short of modelling and evolutionary approaches and has developed too independently from general ecology. We have tested quantitatively these hypotheses through a bibliographic study (about 23000 articles) comparing soil ecology journals, generalist ecology journals, evolutionary ecology journals and theoretical ecology journals. FINDINGS: We have shown that soil ecology is not well represented in generalist ecology journals and that soil ecologists poorly use modelling and evolutionary approaches. Moreover, the articles published by a typical soil ecology journal (Soil Biology and Biochemistry) are cited by and cite low percentages of articles published in generalist ecology journals, evolutionary ecology journals and theoretical ecology journals. CONCLUSION: This confirms our hypotheses and suggests that soil ecology would benefit from an effort towards modelling and evolutionary approaches. This effort should promote the building of a general conceptual framework for soil ecology and bridges between soil ecology and general ecology. We give some historical reasons for the parsimonious use of modelling and evolutionary approaches by soil ecologists. We finally suggest that a publication system that classifies journals according to their Impact Factors and their level of generality is probably inadequate to integrate "particularity" (empirical observations) and "generality" (general theories), which is the goal of all natural sciences. Such a system might also be particularly detrimental to the development of a science such as ecology that is intrinsically multidisciplinary

Ability of Group IVB metallocene polyethers containing dienestrol to arrest the growth of selected cancer cell lines

<p>Abstract</p> <p>Background</p> <p>Monomeric Group IVB (Ti, Zr and Hf) metallocenes represent a new class of antitumor compounds. There is literature on the general biological activities of some organotin compounds. Unfortunately, there is little information with respect to the molecular level activity of these organotin compounds. We recently started focusing on the anti-cancer activity of organotin polymers that we had made for other purposes and as part of our platinum anti-cancer effort.</p> <p>Methods</p> <p>For this study, we synthesized a new series of metallocene-containing compounds coupling the metallocene unit with dienestrol, a synthetic, nonsteroidal estrogen. This is part of our effort to couple known moieties that offer antitumor activity with biologically active units hoping to increase the biological activity of the combination. The materials were confirmed to be polymeric using light scattering photometry and the structural repeat unit was verified employing matrix assisted laser desorption ionization mass spectrometry and infrared spectroscopy results.</p> <p>Results</p> <p>The polymers demonstrated the ability to suppress the growth of a series of tumor cell lines originating from breast, colon, prostrate, and lung cancers at concentrations generally lower than those required for inhibition of cell growth by the commonly used antitumor drug cisplatin.</p> <p>Conclusion</p> <p>These drugs show great promise in vitro against a number of cancer cell lines and due to their polymeric nature will most likely be less toxic than currently used metal-containing drugs such as cisplatin. These drugs also offer several addition positive aspects. First, the reactants are commercially available so that additional synthetic steps are not needed. Second, synthesis of the polymer is rapid, occurring within about 15 seconds. Third, the interfacial synthetic system is already industrially employed in the synthesis of aromatic nylons and polycarbonates. Thus, the ability to synthesize large amounts of the drugs is straight forward.</p

Razvoj metformin hidroklorida za izravnu kompresiju metodom sušenja raspršivanjem

Metformin hydrochloride exhibits poor compressibility during compaction, often resulting in weak and unacceptable tablets with a high tendency to cap. The purpose of this study was to develop directly compressible metformin hydrochloride by the spray drying technique in the presence of polymer. Metformin hydrochloride was dissolved in solutions containing a polymer, namely polyvinylpyrrolidone (PVP K30), in various concentrations ranging from 0-3 % m/V. These solutions were employed for spray-drying. Spray-dried drug was evaluated for yield, flow property and compressibility profile. Metformin hydrochloride spray-dried in the presence of 2 % PVP K30 showed an excellent flow property and compressibility profile. From the calculated Heckel’s parameter (Py = 2.086), it was demonstrated that the treated drug showed better particle arrangement in the initial compression stage. Kawakita analysis revealed better packability of the treated drug compared to the untreated drug. Differential scanning calorimetry and Fourier transform infrared spectroscopy experiments showed that the spray-dried drug did not undergo any chemical modifications. Tablets made from the spray-dried drug (90 %, m/m) were evaluated for crushing strength, friability and disintegration time and the results were found satisfactory.Metformin hidroklorid se teško komprimira zbog čega nastaju slabe tablete neodgovarajuće kvalitete s velikom tendencijom kalanja. Cilj ovog rada je prirediti metformin hidroklorid za izravnu kompresiju metodom sušenja raspršivanjem u prisutnosti polimera. Metformin hidroklorid je otopljen uz dodatak različitih količina (03 % m/V) polivinilpirolidona (PVP K30). Dobivene otopine sušene su raspršivanjem, a tako pripravljenom metformin hidrokloridu određivano je iskorištenje, tečnost i kompresibilnost. Metformin hidroklorid pripravljen u prisutnosti 2 % PVP K30 ima izvrsnu tečnost i kompresibilnost. Izračunati Heckelovi parametri (Py = 2,086) pokazuju da tako obrađeni metformin hidroklorid tvori veće čestice na početku kompresije. Analiza po Kawakiti ukazuje na to da se obrađeni lijek bolje preša od neobrađenog. Diferencijalna pretražna kalorimetrija (DSC) i Fourierova transformirana infracrvena spektroskopija (FTIR) pokazuju da sušenje raspršivanjem nije uzrokovalo nikakve kemijske promjene. Iz obrađenog metformina izrađene su tablete (90 % m/m) sa zadovoljavajućom lomljivošću, drobivošću i vremenom dezintegracije

Large body size constrains dispersal assembly of communities even across short distances

International audienc

The CAFA challenge reports improved protein function prediction and new functional annotations for hundreds of genes through experimental screens

Background: The Critical Assessment of Functional Annotation (CAFA) is an ongoing, global, community-driven effort to evaluate and improve the computational annotation of protein function. Results: Here, we report on the results of the third CAFA challenge, CAFA3, that featured an expanded analysis over the previous CAFA rounds, both in terms of volume of data analyzed and the types of analysis performed. In a novel and major new development, computational predictions and assessment goals drove some of the experimental assays, resulting in new functional annotations for more than 1000 genes. Specifically, we performed experimental whole genome mutation screening in Candida albicans and aeruginosa genomes, which provided us with genome-wide experimental data for genes associated with biofilm formation and motility. We further performed targeted assays on selected genes in Drosophila melanogaster, which we suspected of being involved in long-term memory. Conclusion: We conclude that while predictions of the molecular function and biological process annotations have slightly improved over time, those of the cellular component have not. Term-centric prediction of experimental annotations remains equally challenging; although the performance of the top methods is significantly better than the expectations set by baseline methods in C. albicans and D. melanogaster, it leaves considerable room and need for improvement. Finally, we report that the CAFA community now involves a broad range of participants with expertise in bioinformatics, biological experimentation, biocuration, and bio-ontologies, working together to improve functional annotation, computational function prediction, and our ability to manage big data in the era of large experimental screens