458 research outputs found

    The PEPA workbench: A tool to support a process algebra-based approach to performance modelling

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    . In this paper we present a new technique for performance modelling and a tool supporting this approach. Performance Evaluation Process Algebra (PEPA) [1] is an algebraic language which can beused to build models of computer systems which capture information about the performance of the system. The PEPA language serves two purposes as a formal description language for computer system models. The performance-related information in the model may be used to predict the performance of the system whereas the behavioural information in the model may be exploited when reasoning about the functional behaviour of the system (e.g. when finding deadlocks or when exhibiting equivalences between sub-components). In this paper we concentrate on the performance aspects of the language. A method of reasoningaboutPEPA modelsproceedsby considering the derivation graph obtained from the model using the underlying operational semantics of the PEPA language. The derivation graph is systematically reduced ..

    Spectroscopic Confirmation of an Ultramassive and Compact Galaxy at Z = 3.35: A Detailed Look at an Early Progenitor of Local Giant Ellipticals

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    We present the first spectroscopic confirmation of an ultra-massive galaxy at redshift z\u3e3 using data from Keck-NIRSPEC, VLT-Xshooter, and GTC-Osiris. We detect strong [OIII] and Lyα emission, and weak [OII], CIV, and HeII, placing C1-23152 at a spectroscopic redshift of zspec=3.351. The modeling of the emission-line corrected spectral energy distribution results in a best-fit stellar mass of M∗=3.1+0.6−0.7×1011M⊙, a star-formation rate of \u3c7 M⊙yr−1, and negligible dust extinction. The stars appear to have formed in a short intense burst ~300-500 Myr prior to the observation epoch, setting the formation redshift of this galaxy at z~4.1. From the analysis of the line ratios and widths, and the observed flux at 24μm, we confirm the presence of a luminous hidden active galactic nucleus (AGN), with bolometric luminosity of ~1046ergs−1. Potential contamination to the observed SED from the AGN continuum is constrained, placing a lower limit on the stellar mass of 2×1011M⊙. HST/WFC3 H160 and ACS I814 images are modeled, resulting in an effective radius of re~1 kpc in the H160 band and a Sersic index n~4.4. This object may be a prototype of the progenitors of local most massive elliptical galaxies in the first 2 Gyr of cosmic history, having formed most of its stars at z\u3e4 in a highly dissipative, intense, and short burst of star formation. C1-23152 is completing its transition to a post-starburst phase while hosting a powerful AGN, potentially responsible for the quenching of the star formation activity

    Gene co-expression networks in liver and muscle transcriptome reveal sex-specific gene expression in lambs fed with a mix of essential oils

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    Background: Essential oil (EO) dietary supplementation is a new strategy to improve animal health. EO compounds have antiparasitic, antimicrobial, antiviral, antimycotic, antioxidant and anti-inflammatory proprieties. Nutrigenomics investigations represent innovative approaches in understanding the relation between diet effect and gene expression related to the animal performance. Few nutrigenomics studies have used a high-throughput RNA-Sequencing (RNA-Seq) approach, despite great potential of RNA-Seq data in gene expression quantification and in co-expression network analyses. Our aim is to use the potential of RNA-Sequencing data in order to evaluate the effect of an EO supplementary diet on gene expression in both lamb liver and muscle. Results: Using a treatment and sex interaction model, 13 and 4 differentially expressed genes were identified in liver and muscle respectively. Sex-specific differentially expressed (DE) genes were identified in both sexes. Using network based analysis, different clusters of co-expressed genes that were highly correlated to the diet were detected in males vs. females, in agreement with DE analysis. A total of five regulatory genes in liver tissue associated to EO diet were identified: DNAJB9, MANF, UFM1, CTNNLA1 and NFX1. Our study reveals a sex-dependent effect of EO diet in both tissues, and an influence on the expression of genes mainly involved in immune, inflammatory and stress pathway. Conclusion: Our analysis suggests a sex-dependent effect of the EO dietary supplementation on the expression profile of both liver and muscle tissues. We hypothesize that the presence of EOs could have beneficial effects on wellness of male lamb and further analyses are needed to understand the biological mechanisms behind the different effect of EO metabolites based on sex. Using lamb as a model for nutrigenomics studies, it could be interesting to investigate the effects of EO diets in other species and in humans

    Embedding real-time in stochastic process algebras

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    We present a stochastic process algebra including immediate actions, deadlock and termination, and explicit stochastic delays, in the setting of weak choice between immediate actions and passage of time. The operational semantics is a spent time semantics, avoiding explicit clocks. We discuss the embedding of weak-choice real-time process theories and analyze the behavior of parallel composition in the weak choice framework

    Biomimetic nanocrystalline apatite coatings synthesized by Matrix Assisted Pulsed Laser Evaporation for medical applications

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    tWe report the deposition by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique of biomimeticnanocrystalline apatite coatings on titanium substrates, with potential application in tissue engineering.The targets were prepared from metastable, nanometric, poorly crystalline apatite powders, analogousto mineral bone, synthesized through a biomimetic approach by double decomposition process. For thedeposition of thin films, a KrF* excimer laser source was used (λ = 248 nm, τFWHM ≤ 25 ns). The analy-ses revealed the existence, in synthesized powders, of labile non-apatitic mineral ions, associated withthe formation of a hydrated layer at the surface of the nanocrystals. The thin film analyses showedthat the structural and chemical nature of the nanocrystalline apatite was prevalently preserved. Theperpetuation of the non-apatitic environments was also observed. The study indicated that MAPLE isa suitable technique for the congruent transfer of a delicate material, such as the biomimetic hydratednanohydroxyapatite

    Surgical sterilization of male and female grey squirrels (Sciurus carolinensis) of an urban population introduced in Italy

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    We report a successful surgical sterilization procedure for population control of 324 male and female free-ranging grey squirrels (Sciurus carolinensis) in Genoa (Italy). We describe the clinical procedure from the trapping of the animals to their surgical sterilization and release in another part of the city. Live-trapped squirrels were transported to the veterinary clinic within 1-2 hr of capture and maintained in a hospitalization room reserved for them. The waiting period before surgery was kept below 12 hr. The developed procedure has resulted in a survival of 94% of trapped squirrels from surgery to animal release. Sterilized squirrels started to feed in a very short time (1.0-1.5 hr), and after 2-3 days, it was possible to release them in a new area. Amoxicillin was used as a long-acting postoperative antibiotic to reduce the period of captivity. The successful surgical procedure described here can provide an important additional tool for the management of introduced populations of squirrels. We showed that the surgical sterilization of some hundred squirrels is clinically possible and could be included in management strategies aimed at removing critical populations of these species. Moreover, the data allow dosages and operational times in order to provide economic viability assessment of future population control measures
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