Search

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.comnet.2008.09.009 Byline: V. Eramo (a), A. Germoni (a), C. Raffaelli (b), M. Savi (b) Keywords: Optical packet switching; Contention resolution; Wavelength converters sharing; Scheduling algorithm; Loss performance Abstract: This paper discusses a multi-fiber all-optical switch which shares wavelength converters for contention resolution. The proposed switch architecture employs fixed-input/tunable-output wavelength converters (expected to be less complex than tunable-input/tunable-output ones). The space switching matrix is modular and simple with respect to switching architectures with different wavelength converters sharing schemes (i.e. shared-per-node architecture). A parallel scheduling algorithm is defined to control optical packet forwarding in a synchronous scenario as well as an analytical model to evaluate packet loss performance. The analytical model is validated against simulation and previous analysis and the results obtained show good accuracy in most cases of interest for optical switch design. Author Affiliation: (a) INFOCOM Department, University of Rome, "Sapienza" Via Eudossiana 18, 00184 Rome, Italy (b) D.E.I.S., University of Bologna, Viale Risorgimento 2, 40136 Bologna, Italy

The geometrically non-linear elastic thin composite layer model is developed through the application of the modified asymptotic homogenization method. The set of local unit cell problems and the analytical formulae for the effective stiffness moduli of the non-linear homogenized plate accounting the higher order terms of the asymptotic expansions are derived. They make it possible to gain useful insight into the manner in which the geometrical and mechanical properties of the individual constituents affect the elastic properties of the composite layer with wavy surfaces. It is shown that in the limiting case of a homogeneous layer of constant thickness the derived asymptotic homogenization model converges to the geometrically non-linear mean-flexure plate theory. And the obtained expressions for the mid-surface strains converge to von Kármán's formulae. The derived non-linear homogenization model is illustrated by an example of a laminated plate. [ABSTRACT FROM AUTHOR]

Interest in the toxicity of pesticides has increased as they enter waterways from agricultural and urban runoffs and may end up in aquatic environment and bioaccumulate in the food chain. The aim of this study was to determine the effect of two insecticides; Chlorpyrifos and Cypermethrin on aquatic protozoa (Paramecium). The test was carried out in laboratory, where Monoxenic culture of Paramecium was used to test the effect of Chlorpyrifos and Cypermethrin at 50, 25, 12.5, 6.25, 3.125, 1 respectively, at time interval of 24, 48, and 72 hours. The effect of Chlorpyrifos on Paramecium growth showed significant different with P value 0.0228, while for Cypermethrin, there was no significant difference with P value of 0.1333. The damage was more at 24hrs interval, as the number of population growth increased with time. Hence, the effect of the insecticides reduced. Conclusively, both insecticides showed harmful effect to Paramecium and may disturb the aquatic ecosystem. [ABSTRACT FROM AUTHOR]

Abstract: Background and aims: Trans-resveratrol (RSV) is a natural compound occurring in different foods and plants, which in vivo is rapidly conjugated with glucuronic acid and sulfate. Despite its demonstrated cardioprotective activity, the bioaccumulation of RSV or its metabolites in cardiac tissue is still unknown. Methods and results: Diabetic rats were randomized to 1, 3 or 6 weeks of RSV treatment at two different doses (1 or 5 mg/kg/day). A dose and time-dependent accumulation was observed, with no detectable levels of RSV metabolites found in heart tissues after 1 week and significant concentrations of RSV-3-sulfate and RSV-3-glucuronide after 6 weeks of treatment (0.05 nmol/g of tissue and 0.01 nmol/g of tissue, respectively). Tissue accumulation of RSV metabolites was accompanied by an improvement of cardiac function in long-term diabetes, when myocardial morpho-functional damage is more evident, with an almost complete recovery of all hemodynamic parameters, at the highest RSV dose. Conclusion: Even if a higher concentration of RSV in tissues cannot be ruled out after constant oral administration, an accumulation coherent with what is usually evaluated in cell based mechanistic studies is largely unattainable and the RSV unconjugated form would not be present in this paradigm. The current investigation provides data on myocardial tissue concentrations of RSV metabolites, after short/medium term RSV treatment. This knowledge constitutes a basic requirement for future studies aimed at reliably defining the molecular pathways underlying RSV-mediated cardioprotective effects and opens up new perspectives for research focused on testing phenolic compounds as adjuvants in degenerative heart diseases. [Copyright &y& Elsevier]

The dynamical response of systems with shape memory alloy (SMA) elements presents a rich behavior due to their intrinsic nonlinear characteristic. SMA's nonlinear response is associated with both adaptive dissipation related to hysteretic behavior and huge changes in properties caused by phase transformations. These characteristics are attracting much technological interest in several scientific and engineering fields, varying from medical to aerospace applications. An important characteristic associated with dynamical response of SMA system is the jump phenomenon. Dynamical jumps result in abrupt changes in system behavior and its analysis is essential for a proper design of SMA systems. This paper discusses the nonlinear dynamics of a one degree of freedom SMA oscillator presenting pseudoelastic behavior and dynamical jumps. Numerical simulations show different aspects of this kind of behavior, illustrating its importance for a proper understanding of nonlinear dynamics of SMA systems. [ABSTRACT FROM AUTHOR]

A new wavelength converter sharing strategy for multifiber optical switches, namely shared-per-wavelength (SPW), which employs wavelength converters with fixed input wavelengths is presented. The aim is to reduce switch costs by using simpler optical components and low complexity space switching matrices. Practical implementations of both the well-known shared-per-node (SPN) and the new SPW schemes are presented, as well as the related scheduling algorithms to manage optical packet forwarding in synchronous scenario. An analytical model to evaluate blocking performance of the SPN architecture is also provided. Results show the accuracy of the model in the range of interest for switch design. The proposed architectures are compared in terms of performance and number of optical components employed. The SPW approach is shown to save a large number of semiconductor optical amplifier gates with respect to the SPN one when the number of fibers per interface is suitably not too high. In these cases, the SPW architecture requires a number of wavelength converters higher than the SPN, but simpler, being their inputs tuned on a single wavelength. [ABSTRACT FROM PUBLISHER]

The inter-hemispheric symmetry of electroencephalographic (EEG) post-movement beta-event-related synchronization (PMBS) after movements on a drawing board was studied in eight acute stroke subjects with mild hemiparesis and eight normal subjects. A follow-up testing was conducted 3 months after the initial recordings with a twofold purpose: (1) to validate the reproducibility of the experimental protocol in normal subjects; and (2) to study changes of inter-hemispheric PMBS-symmetry as a response to recovery of motor function. PMBS values were calculated and their topographic distributions illustrated at various time instances following movement offset. Significant PMBS patterns were present in all normal subjects, with only minor differences within consecutive recordings. The side of hemiparesis in acute stroke subjects could be distinguished ( P = 0.04) on the basis of the signed symmetry index, a quantitative measure of lateralization. The follow-up testing on three recovered stroke subjects revealed a trend of changes in the lateralization towards the contralateral side of movement, an indication that the cortical organization of movement following recovery turned out as reported for normal subjects. Further clinical investigations need to be carried out to evaluate the relationship between recovery and PMBS symmetry on a large number of subjects, using the method presented here. [ABSTRACT FROM AUTHOR]

The determination of residual stresses is an important task in the analysis of the quenching process. Nevertheless, because of the complexity of the phenomenon, many simplifications are usually adopted in the prediction of these stresses for engineering purposes. One of these simplifications is the effect of phase transformation. Many studies analyse residual stresses generated by the quenching process considering a thermoelastoplastic approach, neglecting phase transformation. The present study analyses the effect of austenite–martensite phase transformation during quenching in the determination of residual stresses, comparing two different models: complete (thermoelastoplastic model with austenite–martensite phase transformation) and without phase transformation (thermoelastoplastic model without phase transformation). The finite element method is employed for spatial discretization together with a constitutive model that represents the thermomechanical behaviour of the quenching process. Progressive induction hardening of steel cylinders with semicircular notches is of concern. Numerical simulations show situations where great discrepancies are introduced in the predicted residual stresses if phase transformation is neglected. [ABSTRACT FROM AUTHOR]

Shape memory and pseudoelastic effects are thermomechanical phenomena associated with martensitic phase transformations, presented by shape memory alloys. The dynamical analysis of intelligent systems that use shape memory actuators involves a multi-degree of freedom system. This contribution concerns with the chaotic response of shape memory systems. Two different systems are considered: a single and a two-degree of freedom oscillator. Equations of motion are formulated assuming a polynomial constitutive model to describe the restitution force of oscillators. Since equations of motion of the two-degree of freedom oscillator are associated with a five-dimensional system, the analysis is performed considering two oscillators, both with single-degree of freedom, connected by a spring-dashpot system. With this assumption, it is possible to analyze the transmissibility of motion between two oscillators. Results show some relation between the transmissibility of order, chaos and hyperchaos with temperature. [ABSTRACT FROM AUTHOR]

The internal stresses generated during quenching can produce warping and even cracking of a steel body and, therefore, the prediction of such stresses is an important task. Phenomenological aspects of quenching involve couplings between different physical processes occurring in the phenomena. The present contribution is concerned with modelling and simulation of quenching, presenting an anisothermal model formulated within the framework of continuum mechanics and the thermodynamics of irreversible processes. A numerical procedure is developed based on an operator split technique associated with an iterative numerical scheme in order to deal with non-linearities in the formulation. With this assumption, the coupled governing equations are solved involving four uncoupled problems: thermal, phase transformation, thermoelastic and elastoplastic behaviours. The proposed general formulation is applied to analyse progressive induction hardening of steel cylinders. Numerical results suggest that the proposed model is capable of capturing the main behaviour observed in experimental data. [ABSTRACT FROM AUTHOR]

Delamination is a phenomenon characterized by the loss of adhesion between two adjacent laminae. This is a damage process frequently observed in composite materials and it may cause either loss of structural stiffness or total failure of the laminate. This contribution presents a model to describe composite delamination. The proposed model considers a laminate with a finite thickness interlayer. Interlaminar stresses are evaluated from a modified lamination theory. This result is used as input in the constitutive adhesion model which describes the damage evolution of the interlayer. An iterative numerical procedure is developed, solving the model equations separately. This work considers numerical simulations of a laminated tube and a laminated bar as applications of the proposed general formulation. Numerical results are capable of capturing the general behaviour of experimental data. [ABSTRACT FROM AUTHOR]

Contents The aim of this study was to estimate the effects of Equex STM on sperm motion characteristics in chilled dog semen extended in Tris-based diluent. Thirty-two ejaculates were collected from 12 proven German shepherd stud dogs. The sperm-rich fractions were diluted in Tris-based extender with 1% (v/v) Equex STM (sample A) and in Tris-based extender with no addition of detergent (sample B). The extended semen was incubated for 240 h at 5°C and the motility parameters were evaluated by CASA system at 24-h intervals. Addition of Equex STM to Tris-based extender led to an initial activation of motion activity of spermatozoa, followed by a rapid decrease, shortening the lifespan of spermatozoa incubated at 5°C. Computer-assisted sperm analysis clearly showed that Equex STM-induced changes of sperm motion characteristics resemble the hyperactivation (HA) of spermatozoa associated with the capacitation process. [ABSTRACT FROM AUTHOR]

In this work, a helical spring made from a pseudoelastic shape memory alloy was embedded in a dynamic system also composed of a mass, a linear spring and an excitation system. The mechanical behaviour of shape memory alloys is highly complex, involving hysteresis, which leads to damping capabilities and varying stiffness. Besides, these properties depend on the temperature and pretension conditions. Because of these capabilities, shape memory alloys are interesting in relation to engineering design of dynamic systems. A theoretical model based on a modification of the 1D Brinson model was established. Basically, the hardening and the sub-loop behaviour were altered. The model parameters were extracted from force–displacement tests of the spring at different constant temperatures as well as from differential scanning calorimetry. Model predictions were compared with experimental results of free and forced vibrations of the system setup under different temperature conditions. The experiments give a thorough insight into dynamic systems involving pseudoelastic shape memory alloys. Comparison between experimental results and the proposed model shows that the model is able to explain and predict the overall nonlinear behaviour of the system. [ABSTRACT FROM AUTHOR]

Cardiac rhythms are related to heart electrical activity, being the essential aspect of the cardiovascular physiology. Usually, these rhythms are represented by electrocardiograms (ECGs) that are useful to detect cardiac pathologies. Essentially, the heart activity starts in the sinoatrial node (SA) node, the natural pacemaker, propagating to the atrioventricular node (AV), and finally reaching the His-Purkinje complex (HP). This paper investigates the control of cardiac rhythms in order to induce normal rhythms from pathological responses. A mathematical model that presents close agreement with experimental measurements is employed to represent the heart functioning. The adopted model comprises a network of three nonlinear oscillators that represent each one of the cardiac nodes, connected by delayed couplings. The pathological behavior is induced by an external stimulus in the SA node. An adaptive controller is proposed acting in the SA node considering an strategy based on the signal obtained by the natural pacemaker and its regularization. The incorporation of adaptive compensation in a Lyapunov-based control scheme allows the compensation for the unknown dynamics. The controller ability to deal with interpatient variability is evaluated by assuming that the heart model is not available to the controller design, being used only in the simulator to assess the control performance. Results show that the adaptive term can reduce the control effort by around 3% while reducing the tracking error by 20%, when compared to the conventional feedback approach. Additionally, the controller can avoid abnormal rhythms, turning the ECG closer to the expected normal behavior and preventing critical cardiac responses. Therefore, this work demonstrates that an adaptive controller can be used to regulate the ECG signal without prior information about the system and disregarding inter- and intrapatient variability., (© 2024. The Author(s).)

Acute brain injury (ABI) remains one of the leading causes of death and disability world-wide. Its treatment is challenging due to the heterogeneity of the mechanisms involved and the variability among individuals. This systematic review aims at evaluating the impact of anti-histone treatments on outcomes in ABI patients and experimental animals and defining the trend of nucleosome levels in biological samples post injury. We performed a search in Pubmed/Medline and Embase databases for randomized controlled trials and cohort studies involving humans or experimental settings with various causes of ABI. We formulated the search using the PICO method, considering ABI patients or animal models as population (P), comparing pharmacological and non-pharmacological therapy targeting the nucleosome as Intervention (I) to standard of care or no treatment as Control (C). The outcome (O) was mortality or functional outcome in experimental animals and patients affected by ABI undergoing anti-NET treatments. We identified 28 studies from 1246 articles, of which 7 were experimental studies and 21 were human clinical studies. Among these studies, only four assessed the effect of anti-NET therapy on circulating markers. Three of them were preclinical and reported better outcome in the interventional arm compared to the control arm. All the studies observed a significant reduction in circulating NET-derived products. NETosis could be a target for new treatments. Monitoring NET markers in blood and cerebrospinal fluid might predict mortality and long-term outcomes. However, longitudinal studies and randomized controlled trials are warranted to fully evaluate their potential, as current evidence is limited.

Hepatorenal Syndrome is a critical complication of liver failure, mainly in cirrhotic patients and rarely in patients with acute liver disease. It is a complex spectrum of conditions that leads to renal dysfunction in the liver cirrhosis population; the pathophysiology is characterized by a specific triad: circulatory dysfunction, nitric oxide (NO) dysfunction and systemic inflammation but a specific kidney damage has never been demonstrated, in a clinicopathological study, kidney biopsies of patients with cirrhosis showed a wide spectrum of kidney damage. In addition, the absence of significant hematuria or proteinuria does not exclude renal damage. It is estimated that 40% of cirrhotic patients will develop hepatorenal syndrome with in-hospital mortality of about one-third of these patients. The burden of the problem is dramatic considering the worldwide prevalence of more than 10 million decompensated cirrhotic patients, and the age-standardized prevalence rate of decompensated cirrhosis has gone through a significant rise between 1990 and 2017. Given the syndrome's poor prognosis, the clinician must know how to manage early treatment and any complications. The widespread adoption of albumin and vasopressors has increased Hepatorenal syndrome-acute kidney injury reversal and may increase overall survival, as previously shown. Further research is needed to define whether the subclassification of patients may allow to find a personalized strategy to treat Hepatorenal Syndrome and to define the role of new molecules and extracorporeal treatment may allow better outcomes with a reduction in treatment-related adverse effects. This review aims to examine both pharmacological and non-pharmacological treatment of hepatorenal syndrome, with a particular focus on managing adverse events caused by treatment.

Circulating nucleosome levels are commonly elevated in physiological and pathological conditions. Their potential as biomarkers for diagnosing and prognosticating sepsis remains uncertain due, in part, to technical limitations in existing detection methods. This scoping review explores the possible role of nucleosome concentrations in the diagnosis, prognosis, and therapeutic management of sepsis. A comprehensive literature search of the Cochrane and Medline libraries from 1996 to 1 February 2024 identified 110 potentially eligible studies, of which 19 met the inclusion criteria, encompassing a total of 39 SIRS patients, 893 sepsis patients, 280 septic shock patients, 117 other ICU control patients, and 345 healthy volunteers. The enzyme-linked immunosorbent assay [ELISA] was the primary method of nucleosome measurement. Studies consistently reported significant correlations between nucleosome levels and other NET biomarkers. Nucleosome levels were higher in patients with sepsis than in healthy volunteers and associated with disease severity, as indicated by SOFA and APACHE II scores. Non-survivors had higher nucleosome levels than survivors. Circulating nucleosome levels, therefore, show promise as early markers of NETosis in sepsis, with moderate diagnostic accuracy and strong correlations with disease severity and prognosis. However, the available evidence is drawn mainly from single-center, observational studies with small sample sizes and varied detection methods, warranting further investigation.

The impact of psychosocial stressors on cardiovascular health in women is of growing interest in both the popular and scientific literature. Rodent models are useful for providing direct experimental evidence of the adverse cardiovascular consequences of psychosocial stressors, yet studies in females are scarce. Here, we investigated the effects of repeated exposure to witness social defeat stress (WS) on cardiomyocyte contractile function and intracellular Ca 2+ homeostasis in young adult wild-type Groningen female rats. Female rats bore witness to an aggressive social defeat episode between two males for nine consecutive days or were exposed to a control procedure. Stress-related behaviors were assessed during the first and last WS/control exposure. Twenty-four hours after the last exposure, plasma corticosterone levels were measured, and cardiomyocytes were isolated for analyses of contractile properties and Ca 2+ transients, and expression levels of proteins involved in intracellular Ca 2+ dynamics. The results show an impairment of the intrinsic cardiac mechanical properties and prolonged intracellular Ca 2+ decay in WS female rats showing social stress-related behavioral (larger amounts of burying behavior) and neuroendocrine (elevated plasma corticosterone levels) phenotypes. Further, the results implicate alterations in the sarcoplasmic reticulum Ca 2+ -ATPase/phospholamban complex in the contractile defects described in cardiomyocytes of WS female rats. In conclusion, this study highlights the utility of the WS model as an ethologically relevant social stressor for investigating pathophysiological processes that occur in the heart of female subjects and may increase vulnerability to social stress-related cardiovascular risk., Competing Interests: Declaration of Competing Interest The authors state no conflict of interest., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Lung ultrasound (LUS) is a validated technique for the prompt diagnosis and bedside monitoring of critically ill patients due to its availability, safety profile, and cost-effectiveness. The aim of this work is to detect similarities and differences among LUS reports performed in ICUs and to provide a common ground for an integrated report form. We collected all LUS reports during an index week in 21 ICUs from the GiViTI network. First, we considered signs, chest areas, and terminology reported. Then, we compared different report structures and categorized them as structured reports (SRs), provided with a predefined model form, and free unstructured text reports (FTRs) that had no predetermined structure. We analyzed 171 reports from 21 ICUs, and 59 reports from 5 ICUs were structured. All the reports presented a qualitative description that mainly focused on the presence of B-lines, consolidations, and pleural effusion. Zones were defined in 66 reports (39%). In SRs, a complete examination of all the regions was more frequently achieved (96% vs. 74%), and a higher impact on therapeutic strategies was observed (17% vs. 6%). LUS reports vary significantly among different centers. Adopting an integrated SR seems to promote a systematic approach in scanning and reporting, with a potential impact on LUS clinical applications.

Chronic social stress has been epidemiologically linked to increased risk for cardiovascular disease, yet the underlying pathophysiological mechanisms are still largely elusive. Mitochondrial (dys)function represents a potential intersection point between social stress exposure and (mal)adaptive cardiac responses. In this study, we used a rodent model of social stress to study the extent to which alterations in the cellular mechanical properties of the heart were associated with changes in indexes of mitochondrial function. Male adult rats were exposed to repeated episodes of social defeat stress or left undisturbed (controls). ECG signals were recorded during and after social defeat stress. Twenty-four hours after the last social defeat, cardiomyocytes were isolated for analyses of mechanical properties and intracellular Ca 2+ dynamics, mitochondrial respiration, and ATP content. Results indicated that social defeat stress induced potent cardiac sympathetic activation that lasted well beyond stress exposure. Moreover, cardiomyocytes of stressed rats showed poor contractile performance (e.g., slower contraction and relaxation rates) and intracellular Ca 2+ derangement (e.g., slower Ca 2+ clearing), which were associated with indexes of reduced reserve respiratory capacity and decreased ATP production. In conclusion, this study suggests that repeated social stress provokes impaired cardiomyocyte contractile performance and signs of altered mitochondrial bioenergetics in the rat heart. Future studies are needed to clarify the causal link between cardiac and mitochondrial functional remodeling under conditions of chronic social stress., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors. Published by Elsevier Ltd.)