674 research outputs found
Isocurvature fluctuations in the effective Newton's constant
We present a new isocurvature mode present in scalar-tensor theories of
gravity that corresponds to a regular growing solution in which the energy of
the relativistic degrees of freedom and the scalar field that regulates the
gravitational strength compensate during the radiation dominated epoch on
scales much larger than the Hubble radius. We study this isocurvature mode and
its impact on anisotropies of the cosmic microwave background for the simplest
scalar-tensor theory, i.e. the extended Jordan-Brans-Dicke gravity, in which
the scalar field also drives the acceleration of the Universe. We use Planck
data to constrain the amplitude of this isocurvature mode in the case of fixed
correlation with the adiabatic mode and we show how this mode could be
generated in a simple two field inflation model.Comment: Version updated to match published version. No changes in the result
A measurement method of routing flexibility in manufacturing systems
Article history: Received 27 January 2011 Received in revised form 25 February 2011 Accepted 2 March 2011 Available online 3 March 2011 This paper focuses on routing flexibility, which is the ability to manufacture a part type via several routes and/or to perform different operations on more than one machine. Specifically, the paper presents a comprehensive method for the measurement of routing flexibility, in a generic manufacturing system. The problem is approached in a modular way, starting from a basic set of flexibility indexes. These are progressively extended to include more comprehensive and complex routing attributes, such as: the average efficiency, the range and the homogeneous distribution of the alternative routes. Two procedures are finally proposed to compare manufacturing systems in terms of routing flexibility. The first one uses a vectorial representation of the previously defined indexes and the second one is based on data envelopment analysis, a multi-criteria decision making approach. The paper concludes with a numerical example, supported by discrete event simulation, which validates the proposed approach. © 2011 Growing Science Ltd. All rights reserve
Quantitative real time PCR approach to study gene expression profile during prenatal growth of skeletal muscle in pig of Duroc and Pietrain breeds
The quantitative real time-PCR (QRT-PCR) is a very sensitive method used to quantify mRNA level in gene expression analysis. Combining amplification, detection and quantification in a single step, allows a more accurate measurement compared to the traditional PCR end point analysis (Pfaffl, 2001; Bustin, 2002)
M/M/1 queuing model with ordinary maintenance and breakdowns
An M/M/1 system with ordinary maintenance and possibility of breakdowns is considered from a practical point of view. An appropriate equation for the probability of n units in the system at any instant of time is written in terms of the Green function of the conventional M/M/1 model and solved by an iterative technique which imposes a periodic regime state. Some Monte Carlo simulations are used to assess the accuracy of the iterative process, i. e. verify that it really converges to the correct solution. Special attention is turned to the analysis of the error that is introduced if the different breakdowns that may occur during the service interval are replaced by a single cumulative waste of time. Numerical results are reported for the special cases in which this cumulative breakdown in placed at the beginning or at the end of the service interval. or is uniformly distributed. To some extent, part of the analysis is deliberately approximated, even if good accuracy is always preserved. The extension to the M/G/1 model is also considered
High brightness 100 W-50 μm delivery blue laser diode module
Blue laser diodes are emerging as the next revolution in laser material processing, especially for high reflective materials, such as copper and gold. The paper presents the most recent evolution of a family of medium-high power and high brightness devices specifically conceived for micro-machining applications. The modules make use of a proprietary architecture based on the combination of commercial laser diodes in TO9 package. The diodes are first organized in rows staggered along the fast axis, then the rows are multiplexed along the fast axis; finally, wavelength and polarization multiplexing are exploited to achieve up to 100W of power into a 50 μm/0.22NA fiber
Online Motion Planning for Safe Human–Robot Cooperation Using B-Splines and Hidden Markov Models
When humans and robots work together, ensuring safe cooperation must be a priority. This research aims to develop a novel real-time planning algorithm that can handle unpredictable human movements by both slowing down task execution and modifying the robot’s path based on the proximity of the human operator. To achieve this, an efficient method for updating the robot’s motion is developed using a two-fold control approach that combines B-splines and hidden Markov models. This allows the algorithm to adapt to a changing environment and avoid collisions. The proposed framework is thus validated using the Franka Emika Panda robot in a simple start–goal task. Our algorithm successfully avoids collision with the moving hand of an operator monitored by a fixed camera
Deregulated PTEN/PI3K/AKT/mTOR signaling in prostate cancer: Still a potential druggable target?
Although the prognosis of patients with localized prostate cancer is good after surgery, with a favorable response to androgen deprivation therapy, about one third of them invariably relapse, and progress to castration-resistant prostate cancer. Overall, prostate cancer therapies remain scarcely effective, thus it is mandatory to devise alternative treatments enhancing the efficacy of surgical castration and hormone administration. Dysregulation of the phosphoinositide 3-kinase pathway has attracted growing attention in prostate cancer due to the highly frequent association of epigenetic and post-translational modifications as well as to genetic alterations of both phosphoinositide 3-kinase and PTEN to onset and/or progression of this malignancy, and to resistance to canonical androgen-deprivation therapy. Here we provide a summary of the biological functions of the major players of this cascade and their deregulation in prostate cancer, summarizing the results of preclinical and clinical studies with PI3K signaling inhibitors and the reasons of failure independent from genomic changes
Identification of SNPs in the promoter of \u3b2-lactoglobulin gene in three Sicilian goat breeds
The aim of this work was to sequence the full-length promoter region of the caprine
\u3b2-lactoglobulin (\u3b2-lg) gene in three Sicilian goat breeds (Girgentana, Maltese, and Derivata di Siria),
in order to identify polymorphisms, to search for transcription factors (TFs) sites, and to check if polymorphisms
found lay within TFs binding sites. The promoter region of \u3b2-lg gene in Sicilian goat breeds
showed high level of polymorphism due to the presence of 31 SNPs. Binding sites for several TFs were
found within the goat \u3b2-lg promoter and within regions conserved between ovine and caprine species.
Two SNPs were detected within TFs binding sites, such as MPBF and NF-I. Further studies are in
progress to confirm polymorphic sites, to evaluate the possible effect of these mutations on binding
affinity of TFs, their relationship with \u3b2-lg gene expression, and the functional role of SNPs within the
TFs sites of the promoter region on milk trait
skeletal muscle expression analysis of fat metabolism genes in pig
Fat content and backfat thickness are important polygenic parameters influencing meat quality and carcass traits in pigs. Up to now, there is a lack of knowledge on the expression level of the genes encoding for enzymes involved in fatty acid metabolism in porcine skeletal muscle. In the present study we analysed, by quantitative real time PCR, the expression of three genes, acetyl-CoA carboxylase (ACACA), ATP citrate lyase (ACL) and fatty acid synthase (FASN) in skeletal muscle tissue samples of Italian Large White and Italian Duroc pigs with divergent breeding values for backfat thickness or visible intramuscular fat. Significant differences of the expression level for ACACA gene (P=0.04) and for ACL gene (P=0.02) were observed between the two breeds, comparing the samples selected for backfat thickness trait. The expression analysis of FASN gene in the samples with different genotype at the SNP c.265C>T showed that the TT genotype presented the lowest values in both breeds. The differences observed between breeds should be further considered to investigate the putative involvement of these genes on fat deposition traits. - Ricerca e analisi di espressione di geni candidati per la deposizione di grasso nella carne suina in razze con diversa attitudine alla deposizione di grasso intramuscolare
- …