Acetohydroxy acid synthase and threonine deaminase activities, and the biosynthesis of isoleucine-leucine-valine in Streptococcus bovis

Acetohydroxy acid synthase (AHAS) and threonine deaminase (TD) activities were found in Streptococcus bovis and shown to be involved in the biosynthesis of the branched chain amino acids isoleucine, leucine and valine. Apparent lack of repression of AHAS synthesis by the end-products and reduced sensitivity of S. bovis growth to analogues of the branched chain amino acids suggested that secretion of isoleucine, leucine and valine in the growth medium may be a consequence of the regulatory features of AHAS. A glycyl-leucine-resistant mutant with reduced TD activity secreted a reduced amount of isoleucine and an increased amount of valine, which might be a result of the reduced rate of synthesis of the isoleucine precursor alpha-ketobutyrate and of a consequent preferential carbon flow through the valine branch of the pathway.     

Switching Device Based on a Thin Film of an Azo-Containing Polymer for Application in Memory Cells

Results obtained on a conductive multilevel device realized with a 100 nm azo-polymer film are reported. The capability to switch between three different conductance states makes the device versatile both for Write Once Read Many and Write Many Read Many memory cell application. The analysis of the - curves indicates that the hysteretic conductance change with the external voltage can be explained in terms of different hopping distances existing between the nearest neighbors intervening in the two conformational states of the molecular structure.     

A Joint Numerical-Experimental Study on Impact Induced Intra-laminar and Inter-laminar Damage in Laminated Composites

The investigation of the mechanical response of fibre-reinforced composite laminates under impact loads can be very difficult due to the occurrence of simultaneous failure phenomena. Indeed, as a consequence of low velocity impacts, intra-laminar damages, like fibre and matrix cracking, and inter-laminar damages, such as delaminations, can take place simultaneously. These damage mechanisms can lead to significant reductions in strength and stability of the composite structure. In this paper a joint numerical-experimental study is proposed which, by means of non-destructive testing techniques (Ultra-sound and thermography) and non-linear explicit FEM analyses, aims to completely characterise the impact induced damage in composite laminates under low velocity impacts. Indeed the proposed numerical tool has been used to improve the understanding of the experimental data obtained by Non-Destructive Techniques. Applications on samples tested according to the AECMA (European Association of Aerospace Manufacturers) prEn6038 standard at three different impact energies are presented. The interaction between numerical and experimental investigation allowed to obtain an exhaustive insight on the different phases of the impact event considering the inter-laminar damage formation and evolution.     

Leakage tests for Am solid sources used for liquid xenon detector monitoring

Experimental tests are described to check solid ²⁴¹Am radioactive sources used to monitor operation of liquid xenon detectors. In particular, radioactive leakage was tested in extreme temperature conditions following immersion in liquid nitrogen for different time periods. No radioactivity loss was detected from the sources considered. The paper describes the source characteristics, test methods and results obtained.     

Investigating the contribution of linguistic information to quality estimation

This paper describes a study on the contribution of linguistically-informed features to the task of quality estimation for machine translation at sentence level. A standard regression algorithm is used to build models using a combination of linguistic and non-linguistic features extracted from the input text and its machine translation. Experiments with three English–Spanish translation datasets show that linguistic features on their own are not able to outperform shallower features based on statistics from the input text, its translation and additional corpora. However, further analysis suggests that linguistic information can be useful to produce better results if carefully combined with other features. An in-depth analysis of the results highlights a number of issues related to the use of linguistic features.     

A two-step,fourth-order method with energy preserving properties

We introduce a family of fourth-order two-step methods that preserve the energy function of canonical polynomial Hamiltonian systems. As is the case with linear mutistep and one-leg methods, a prerogative of the new formulae is that the associated nonlinear systems to be solved at each step of the integration procedure have the very same dimension of the underlying continuous problem.The key tools in the new methods are the line integral associated with a conservative vector field (such as the one defined by a Hamiltonian dynamical system) and its discretization obtained by the aid of a quadrature formula. Energy conservation is equivalent to the requirement that the quadrature is exact, which turns out to be always the case in the event that the Hamiltonian function is a polynomial and the degree of precision of the quadrature formula is high enough. The non-polynomial case is also discussed and a number of test problems are finally presented in order to compare the behavior of the new methods to the theoretical results.     

The Role of Testosterone in the Elderly: What Do We Know?

Testosterone is the most important hormone in male health. Aging is characterized by testosterone deficiency due to decreasing testosterone levels associated with low testicular production, genetic factors, adiposity, and illness. Low testosterone levels in men are associated with sexual dysfunction (low sexual desire, erectile dysfunction), reduced skeletal muscle mass and strength, decreased bone mineral density, increased cardiovascular risk and alterations of the glycometabolic profile. Testosterone replacement therapy (TRT) shows several therapeutic effects while maintaining a good safety profile in hypogonadal men. TRT restores normal levels of serum testosterone in men, increasing libido and energy level and producing beneficial effects on bone density, strength and muscle as well as yielding cardioprotective effects. Nevertheless, TRT could be contraindicated in men with untreated prostate cancer, although poor findings are reported in the literature. In addition, different potential side effects, such as polycythemia, cardiac events and obstructive sleep apnea, should be monitored. The aim of our review is to provide an updated background regarding the pros and cons of TRT, evaluating its role and its clinical applicability in different domains.     

Cancer-Related Cachexia: The Vicious Circle between Inflammatory Cytokines,Skeletal Muscle,Lipid Metabolism and the Possible Role of Physical Training

Cachexia is a multifactorial and multi-organ syndrome that is a major cause of morbidity and mortality in late-stage chronic diseases. The main clinical features of cancer-related cachexia are chronic inflammation, wasting of skeletal muscle and adipose tissue, insulin resistance, anorexia, and impaired myogenesis. A multimodal treatment has been suggested to approach the multifactorial genesis of cachexia. In this context, physical exercise has been found to have a general effect on maintaining homeostasis in a healthy life, involving multiple organs and their metabolism. The purpose of this review is to present the evidence for the relationship between inflammatory cytokines, skeletal muscle, and fat metabolism and the potential role of exercise training in breaking the vicious circle of this impaired tissue cross-talk. Due to the wide-ranging effects of exercise training, from the body to the behavior and cognition of the individual, it seems to be able to improve the quality of life in this syndrome. Therefore, studying the molecular effects of physical exercise could provide important information about the interactions between organs and the systemic mediators involved in the overall homeostasis of the body.