398 research outputs found

    Electroweak monopoles with a non-linearly realized weak hypercharge

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    We present a finite-energy electroweak-monopole solution obtained by considering non-linear extensions of the hypercharge sector of the Electroweak Theory, based on logarithmic and exponential versions of electrodynamics. We find constraints for a class of non-linear extensions and also work out an estimate for the monopole mass in this scenario. We finally derive a lower bound for the energy of the monopole and discuss the simpler case of a Dirac magnetic charge.Comment: 8 pages, constructive comments are welcom

    The Role of Hydrophobic Nodes in the Dynamics of Class A beta-Lactamases

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    Class A β-lactamases are known for being able to rapidly gain broad spectrum catalytic efficiency against most β-lactamase inhibitor combinations as a result of elusively minor point mutations. The evolution in class A β-lactamases occurs through optimisation of their dynamic phenotypes at different timescales. At long-timescales, certain conformations are more catalytically permissive than others while at the short timescales, fine-grained optimisation of free energy barriers can improve efficiency in ligand processing by the active site. Free energy barriers, which define all coordinated movements, depend on the flexibility of the secondary structural elements. The most highly conserved residues in class A β-lactamases are hydrophobic nodes that stabilize the core. To assess how the stable hydrophobic core is linked to the structural dynamics of the active site, we carried out adaptively sampled molecular dynamics (MD) simulations in four representative class A β-lactamases (KPC-2, SME-1, TEM-1, and SHV-1). Using Markov State Models (MSM) and unsupervised deep learning, we show that the dynamics of the hydrophobic nodes is used as a metastable relay of kinetic information within the core and is coupled with the catalytically permissive conformation of the active site environment. Our results collectively demonstrate that the class A enzymes described here, share several important dynamic similarities and the hydrophobic nodes comprise of an informative set of dynamic variables in representative class A β-lactamases

    Fluctuating hydrodynamic modelling of fluids at the nanoscale

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    A good representation of mesoscopic fluids is required to combine with molecular simulations at larger length and time scales (De Fabritiis {\it et. al}, Phys. Rev. Lett. 97, 134501 (2006)). However, accurate computational models of the hydrodynamics of nanoscale molecular assemblies are lacking, at least in part because of the stochastic character of the underlying fluctuating hydrodynamic equations. Here we derive a finite volume discretization of the compressible isothermal fluctuating hydrodynamic equations over a regular grid in the Eulerian reference system. We apply it to fluids such as argon at arbitrary densities and water under ambient conditions. To that end, molecular dynamics simulations are used to derive the required fluid properties. The equilibrium state of the model is shown to be thermodynamically consistent and correctly reproduces linear hydrodynamics including relaxation of sound and shear modes. We also consider non-equilibrium states involving diffusion and convection in cavities with no-slip boundary conditions

    Inflammatory and Adipose Response in Solid Organ Transplant Recipients After a Marathon Cycling Race

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    Abstract Background Organ transplant recipients frequently have chronic inflammation, with a weighty impact on cardiovascular risk. These patients can benefit from exercise, although the role of intense training is unclear. We evaluated the effect of a 130-km cycling race on inflammatory cytokines and adiponectin levels in transplant recipients. Methods Circulating interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and adiponectin were assayed in 35 healthy subjects vs 19 transplant recipients (10 kidney, 8 liver, 1 heart), matched for sex, age, body mass index, and preparation workout. The determinations were performed before the race, at the end, and after 18 to 24 hours. Baseline values of 32 sedentary transplant recipients also were evaluated to explore the possible chronic impact of lifestyle. Results All cyclists had 6- to 8-fold increased IL-6 levels after the race that decreased, without returning to baseline, the day after. Conversely, serum TNF-α and IFN-γ showed a progressive increase starting during physical performance and enduring for the next 18 to 24 hours in healthy subjects, whereas they were unchanged over time in cyclists with transplants. In transplant recipients who did not perform exercise, all of the analytes were significantly higher in comparison to basal levels of physically active subjects. Conclusions Our data suggest that clinically stable and properly trained transplant recipients can safely perform and progressively benefit from exercise, even at a competitive level. The changes in inflammation parameters were temporary and parallel with those of the healthy subjects. The comparison with sedentary transplant recipients revealed an overall amelioration of inflammatory indexes as a possible effect of regular physical activity on systemic inflammation

    Reduced intensity conditioning with thiotepa, fludarabine and melphalan for allogeneic transplantation in multiple myeloma.

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    The reduced intensity conditioning regimen described is feasible, well tolerated in heavily pre-treated patiens. An objective response was obtained in 80% of the patients, 30% achieved a complete response

    Brownian Dynamics Simulation of Polydisperse Hard Spheres

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    Standard algorithms for the numerical integration of the Langevin equation require that interactions are slowly varying during to the integration timestep. This in not the case for hard-body systems, where there is no clearcut between the correlation time of the noise and the timescale of the interactions. Starting from a short time approximation of the Smoluchowsky equation, we introduce an algorithm for the simulation of the overdamped Brownian dynamics of polydisperse hard-spheres in absence of hydrodynamics interactions and briefly discuss the extension to the case of external drifts

    Impact on mental health, disease management, and socioeconomic modifications in hematological patients during the COVID-19 pandemic in Italy

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    Background: Hematological patients are a highly vulnerable population with an increased risk of developing severe COVID-19 symptoms due to their immunocompromised status. COVID-19 has proven to cause serious mental health issues, such as stress, anxiety, and depression in the general population. However, data on the psycho-social impact of COVID-19 on hematological patients are lacking.Objectives: This study aims to examine the psychological well-being of hematological patients in Italy during the initial period of the COVID-19 pandemic. Furthermore, it seeks to explore the association between modifications in the management of hematological diseases and employment status of these patients during the COVID-19 pandemic and the resulting mental health outcomes.Design and Methods: A survey using the DASS-21 questionnaire was administered to 1105 hematological patients. Data analysis was conducted using the R software, and logistic regression analysis was performed to predict the association between hematological patient/general population and employment status with DASS scores.Results: The hematological patient population reported significantly higher levels of depression (OR 0.947, 95% CI 0.966-0.982, p < 0.001), anxiety (OR 0.948, 95% CI 0.939-0.958, p < 0.001), and stress (OR 0.984, 95% CI 0.977-0.992, p < 0.001) compared with the general population. A significant relationship has been found in stress between employed and unemployed patients (OR 1.015, 95% CI 1.000-1.030, p = 0.044), as well as in the control group (OR 1.024, 95% CI 1.010-1.039, p = 0.001). In addition, employment status is significantly related to depression, anxiety, and stress in both the hematological patient group and the general population.Conclusion: During the initial phase of the COVID-19 pandemic, hematological patients had elevated levels of depression, anxiety, and stress compared with the general population. The delay in their treatment and employment status played a role in their mental health outcomes. These findings emphasize the importance of further research to gain deeper insight into the long-term psychological effects and explore effective strategies for managing mental health in similar crises

    Clinical significance of bax/bcl-2 ratio in chronic lymphocytic leukemia

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    In chronic lymphocytic leukemia the balance between the pro-apoptotic and anti-apoptotic members of the bcl-2 family is involved in the pathogenesis, chemorefractoriness and clinical outcome. Moreover, the recently proposed anti-bcl-2 molecules, such as ABT-199, have emphasized the potential role of of bcl-2 family proteins in the context of target therapies. We investigated bax/bcl-2 ratio by flow cytometry in 502 patients and identified a cut off of 1.50 to correlate bax/bcl-2 ratio with well-established clinical and biological prognosticators. Bax/bcl-2 was 1.50 or over in 263 patients (52%) with chronic lymphocytic leukemia. Higher bax/bcl-2 was associated with low Rai stage, lymphocyte doubling time over 12 months, beta-2 microglobulin less than 2.2 mg/dL, soluble CD23 less than 70 U/mL and a low risk cytogenetic profile (P<0.0001). On the other hand, lower bax/bcl-2 was correlated with unmutated IGHV (P<0.0001), mutated NOTCH1 (P<0.0001) and mutated TP53 (P=0.00007). Significant shorter progression-free survival and overall survival were observed in patients with lower bax/bcl-2 (P<0.0001). Moreover, within IGHV unmutated (168 patients) and TP53 mutated (37 patients) subgroups, higher bax/bcl-2 identified cases with significant longer PFS (P=0.00002 and P=0.039). In multivariate analysis of progression-free survival and overall survival, bax/bcl-2 was an independent prognostic factor (P=0.0002 and P=0.002). In conclusion, we defined the prognostic power of bax/bcl-2 ratio, as determined by a flow cytometric approach, and highlighted a correlation with chemoresistance and outcome in chronic lymphocytic leukemia. Finally, the recently proposed new therapies employing bcl-2 inhibitors prompted the potential use of bax/bcl-2 ratio to identify patients putatively resistant to these molecules

    Foundations of Dissipative Particle Dynamics

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    We derive a mesoscopic modeling and simulation technique that is very close to the technique known as dissipative particle dynamics. The model is derived from molecular dynamics by means of a systematic coarse-graining procedure. Thus the rules governing our new form of dissipative particle dynamics reflect the underlying molecular dynamics; in particular all the underlying conservation laws carry over from the microscopic to the mesoscopic descriptions. Whereas previously the dissipative particles were spheres of fixed size and mass, now they are defined as cells on a Voronoi lattice with variable masses and sizes. This Voronoi lattice arises naturally from the coarse-graining procedure which may be applied iteratively and thus represents a form of renormalisation-group mapping. It enables us to select any desired local scale for the mesoscopic description of a given problem. Indeed, the method may be used to deal with situations in which several different length scales are simultaneously present. Simulations carried out with the present scheme show good agreement with theoretical predictions for the equilibrium behavior.Comment: 18 pages, 7 figure
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