Linear Perturbation constraints on Multi-coupled Dark Energy

The Multi-coupled Dark Energy (McDE) scenario has been recently proposed as a specific example of a cosmological model characterized by a non-standard physics of the dark sector of the universe that nevertheless gives an expansion history which does not significantly differ from the one of the standard $\Lambda$CDM model. In this work, we present the first constraints on the McDE scenario obtained by comparing the predicted evolution of linear density perturbations with a large compilation of recent data sets for the growth rate $f\sigma_{8}$, including 6dFGS, LRG, BOSS, WiggleZ and VIPERS. Confirming qualitative expectations, growth rate data provide much tighter bounds on the model parameters as compared to the extremely loose bounds that can be obtained when only the background expansion history is considered. In particular, the $95\%$ confidence level on the coupling strength $|\beta |$ is reduced from $|\beta |\leq 83$ (background constraints only) to $|\beta |\leq 0.88$ (background and linear perturbation constraints). We also investigate how these constraints further improve when using data from future wide-field surveys such as supernova data from LSST and growth rate data from Euclid-type missions. In this case the $95\%$ confidence level on the coupling further reduce to $|\beta |\leq 0.85$. Such constraints are in any case still consistent with a scalar fifth-force of gravitational strength, and we foresee that tighter bounds might be possibly obtained from the investigation of nonlinear structure formation in McDE cosmologies.[Abridged]Comment: 24 pages, 12 figure

Nanostructured nickel film deposition on carbon fibers for improving reinforcement-matrix interface in metal matrix composites

The issues in dispersing any form of carbon in metal matrix is the major problem in the field of metal matrix composites with carbon reinforcement (MMCcr). The low wettability of carbon in molten metals and the difference in density are some of the difficulties to obtain a good dispersion of carbon fibers in the matrix and, as a consequence, an improvement of some critical properties for metals in a wide range of application (mechanical properties, electrical properties, optical properties). For this reason, the aim of this work is to obtain a metallic coated carbon fiber to enhance the interaction between the reinforcement and the matrix. Moreover, also the density of carbon fibers could be adjusted depending on the thickness of the coating. Electroless Nickel-Phosphorus Plating (ENP) is one of the candidate to be a coating technique to improve the interaction between the carbon fibers and the metal matrix. Despite of its versatility in terms of complex geometry of the substrate and homogeneity and adhesion of the coating, the presence of the phosphorus in the alloy could create some problems with the metal matrix such as the formation of metal-phosphorus products that can drastically decrease the mechanical properties of the composite. For this reason, in this work, is presented a new way of Electroless Pure Nickel Plating (EPP) without any introduction of phosphorus in the nickel coating. The dependence of the coating thickness and the density of the coated fibers were studied under different plating parameters (temperature of the plating solution, deposition rate and plating solution composition). All the samples were characterized with SEM and XRD and the thickness, density and homogeneity were compared for all the samples obtained

Supernova constraints on Multi-coupled Dark Energy

The persisting consistency of ever more accurate observational data with the predictions of the standard LCDM cosmological model puts severe constraints on possible alternative scenarios, but still does not shed any light on the fundamental nature of the cosmic dark sector.As large deviations from a LCDM cosmology are ruled out by data, the path to detect possible features of alternative models goes necessarily through the definition of cosmological scenarios that leave almost unaffected the background and -- to a lesser extent -- the linear perturbations evolution of the universe. In this context,the Multi-coupled DE (McDE) model was proposed by Baldi 2012 as a particular realization of an interacting Dark Energy field characterized by an effective screening mechanism capable of suppressing the effects of the coupling at the background and linear perturbation level. In the present paper, for the first time, we challenge the McDE scenario through a direct comparison with real data, in particular with the luminosity distance of Type Ia supernovae. By studying the existence and stability conditions of the critical points of the associated background dynamical system, we select only the cosmologically consistent solutions, and confront their background expansion history with data. Confirming previous qualitative results, the McDE scenario appears to be fully consistent with the adopted sample of Type Ia supernovae, even for coupling values corresponding to an associated scalar fifth-force about four orders of magnitude stronger than standard gravity. Our analysis demonstrates the effectiveness of the McDE background screening, and shows some new non-trivial asymptotic solutions for the future evolution of the universe. Our results show how the background expansion history might be highly insensitive to the fundamental nature and to the internal complexity of the dark sector. [Abridged]Comment: 10 pages, 7 figures. Matches version accepted for publication in JCA

Lightweight metallic matrix composites. Development of new composites material reinforced with carbon structures

Carbon nano/micro-structures used as fillers in metallic lightweight alloys matrix composites are receiving considerable attention in scientific research and industrial applications. Aluminum and magnesium are the most studied light metals used as matrices in metal composites materials principally for their low density (respectively 2.7 g/cm3 and 1.7 g/cm3) and low melting temperature (around 660 °C for both metals). A good interaction between matrix and fillers is the first step to obtain an increase in bulk properties; furthermore, the manufacturing procedure of the composite is fundamental in terms of quality of fillers dispersion. In this work the influence of surface modifications for three classes of carbon fillers for aluminum and magnesium alloy (AZ63) as matrices is studied. In particular, the selected fillers are short carbon micro fibres (SCMFs), carbon woven fabrics (CWF) and unidirectional yarn carbon fibres (UYFs). The surface modification was carried out by a direct coating of pure nickel on fibres. The electroless pure nickel plating was chosen as coating technique and the use of hydrazine as reducing agent has prevented the co-deposition of other elements (such as P or B). SEM and EDS analyses were performed to study the effect of surface modifications. The mechanical properties of manufactured composites were evaluated by four point flexural tests according to ASTM C1161 (room temperature). Results confirm improved interactions between matrix and fillers, and the specific interaction was studied for any chosen reinforcement

Estimating the wage premium to supervision for middle managers in different contexts: evidence from Germany and the UK

The analysis of wage distribution has attracted scholars from different disciplines seeking to develop theoretical arguments to explain the upward or downward trend. In particular, how the middle management wage premium changes in different contexts is a relatively neglected area of research. This study argues that wage distribution changes in different contexts, representing different forms of capitalism. To shed light on this, we considered the size and the shape of the wage premium to supervision paid to middle managers in Germany and the UK. We find evidence of two forms of context: middle managers are paid differently for the same task according to the economy where they work; of this amount, about half of the difference is related to the context. We frame the analysis within the literature on varieties of capitalism

Tribological behaviour of alumina-titania nanostructured coatings produced by air plasma spray technique

Nanostructured Al2O3-TiO2 wear resistant coatings were produced by air plasma spray from plasma-densified agglomerated nano-powders. Conventional Al2O3-TiO2 coatings were also deposited for direct comparison of tribological performance. Operating parameters were optimized by a DOE (Design of Experiment) procedure, to produce coherent and well adherent ceramic coatings and to minimize dwell times in the torch in order to reduce the risk of excessive grain growth or complete remelting. Optimal tribological behaviour was selected as the main goal function. Microstructural characterization of APS nanostructured coatings confirmed the presence of fully molten areas combined with unmolten particles still retaining their spherical morphology, and with elongated particles whose microstructure showed initial stages of grain growth and recrystallization processes. Coatings produced with the final set of deposition parameters were tested for micro-hardness, elastic modulus and unlubricated wear resistance against alumina. Results clearly indicate that nanostructured coatings produced from plasma densified nanostructured precursors exhibit considerably improved performances, evaluated in terms of worn out volume and mass loss

Update on Extended Treatment for Venous Thromboembolism

The importance of assessing the probability of venous thromboembolism recurrence, a condition that includes deep vein thrombosis and pulmonary embolism, lies in the fact that it is the most important factor in deciding the duration of anticoagulant treatment. Risk of recurrence depends mostly on the presence of a risk factor for developing venous thromboembolism, with patients with unprovoked events being at the higher risk of recurrence. The risk of recurrence needs to be balanced with the risk of bleeding and the potential severity of these thrombotic and hemorrhagic events. In patients with an unprovoked venous thromboembolism who complete treatment for the acute (first 10 days) and post-acute phase of the disease (from day 10 to 3-6 months), decision has to be made regarding prolonged antithrombotic therapy to prevent recurrences. The main goal of extended treatment is preventing recurrences with a safe profile in terms of bleeding risk. Many therapeutic options are now available for these patients, including antiplatelet therapy with aspirin or direct oral anticoagulants. Moreover, apixaban and rivaroxaban at prophylactic doses have demonstrated efficacy in preventing recurrences with a low risk of bleeding

Patterns of cerebellar gray matter atrophy across Alzheimer's disease progression

The role of the cerebellum in cognitive function has been broadly investigated in the last decades from an anatomical, clinical, and functional point of view and new evidence points toward a significant contribution of the posterior lobes of the cerebellum in cognition in Alzheimer's disease (AD). In the present work we used SUIT-VBM (spatially unbiased infratentorial template, voxel-based morphometry) to perform an analysis of the pattern of cerebellar gray matter (GM) atrophy in amnestic mild cognitive impairment (a-MCI) and AD dementia patients compared to healthy subjects (HS), in order to follow the changes of non-motor features of cerebellar degeneration throughout disease progression. This template has been validated to guarantee a significant improvement in voxel-to-voxel alignment of the individual fissures and the deep cerebellar nuclei compared to Montreal Neurological Institute (MNI) whole-brain template. Our analysis shows a progression of cerebellar GM volume changes throughout a continuous spectrum from early to late clinical stages of AD. In particular vermis and paravermian areas of the anterior (I-V) and posterior (VI) lobes are involved since the a-MCI stage, with a later involvement of the hemispheric part of the posterior lobes (VI lobule) and Crus I in AD dementia patients only. These findings support the role of the cerebellum in higher-level functions, and whilst confirming previous data on the involvement of Crus I in AD dementia, provide new evidence of an involvement of the vermis in the early stages of the disease

A Patient-Specific Musculoskeletal Model of Total Knee Arthroplasty to Predict In Vivo Knee Biomechanics

Musculoskeletal(MS) models are useful to gain information on in vivo biomechanics that would be otherwise very difficult to obtain.However, before entering the clinical routine MS models must be thoroughlyvalidated. This study presents a novel MS modelling framework capable ofintegrating the patient-specific MS architecture in a very detailed way, andsimultaneously simulating body level dynamics and secondary knee kinematics.The model predictions were further validated against publicly available in vivo experimental data. The bonegeometries were segmented from CT images of a patient with an instrumentedTotal Knee Arthroplasty (TKA) from the “Grand Challenge Competition to Predict In Vivo Knee Loads” dataset. These were inputtedinto an advanced morphing technique in order to scale the MS architecture of thenew TLEM 2.0 model1 to the specific patient. A detailed 11-DOF modelof the knee joint was constructed that included ligaments and rigid contact. Aninverse kinematic and a force-dependent kinematic technique2 wereutilized to simulate one gait cycle and one right-turn trial. Tibiofemoral (TF)joint contact force predictions were evaluated against experimental TF forcesrecorded by the TKA prosthesis, and secondary knee kinematics againstexperimental fluoroscopy data. The coefficientof determination and the root-mean-square error between predicted andexperimental tibiofemoral forces were larger than 0.9 and smaller than 0.3body-weights, respectively, for both gait and right-turn trials. Secondary kneekinematics were estimated with an average Sprague and Geers’ combined error assmall as 0.06. Themodelling strategy proposed permits a high level of patient-specificpersonalization and does not require any non-physiological parameter tuning.The very good agreement between predictions and experimental in vivo data is promising for the futureintroduction of the model into clinical applications

Desmosterolosis: an illustration of diagnostic ambiguity of cholesterol synthesis disorders

Desmosterolosis is an autosomal recessive disorder of cholesterol biosynthesis caused by biallelic mutations of DHCR24 (homozygous or compound heterozygous), which encodes 3-β-hydroxysterol Δ-24-reductase. We report two sisters homozygous for the 571G&gt;A (E191K) DHCR24 mutation. Comparison of the propositae to other reported individuals shows that psychomotor developmental delay, failure to thrive, dysgenesis of the corpus callosum, cerebral white matter atrophy and spasticity likely constitute the minimal desmosterolosis phenotype. The nonspecific features of desmosterolosis make it difficult to suspect clinically and therefore screening for it should be entertained early in the diagnostic evaluation.</p