1,334 research outputs found
Edge channel mixing induced by potential steps in an integer quantum Hall system
We investigate the coherent mixing of co-propagating edge channels in a
quantum Hall bar produced by step potentials. In the case of two edge channels
it is found that, although a single step induces only a few percent mixing, a
series of steps could yield 50% mixing. In addition, a strong mixing is found
when the potential height of a single step allows a different number of edge
channels on the two sides of the step. Charge density probability has been also
calculated even for the case where the step is smoothened.Comment: final version: 7 pages, 6 figure
Action minimizing orbits in the n-body problem with simple choreography constraint
In 1999 Chenciner and Montgomery found a remarkably simple choreographic
motion for the planar 3-body problem (see \cite{CM}). In this solution 3 equal
masses travel on a eight shaped planar curve; this orbit is obtained minimizing
the action integral on the set of simple planar choreographies with some
special symmetry constraints. In this work our aim is to study the problem of
masses moving in \RR^d under an attractive force generated by a potential
of the kind , , with the only constraint to be a simple
choreography: if are the orbits then we impose the
existence of x \in H^1_{2 \pi}(\RR,\RR^d) such that q_i(t)=x(t+(i-1) \tau),
i=1,...,n, t \in \RR, where . In this setting, we first
prove that for every d,n \in \NN and , the lagrangian action
attains its absolute minimum on the planar circle. Next we deal with the
problem in a rotating frame and we show a reacher phenomenology: indeed while
for some values of the angular velocity minimizers are still circles, for
others the minima of the action are not anymore rigid motions.Comment: 24 pages; 4 figures; submitted to Nonlinearit
Respiratory muscle training in patients recovering recent open cardio-thoracic surgery: a randomized-controlled trial.
Objectives- To evaluate the clinical efficacy and feasibility of an expiratory muscle training (EMT) device (Respilift™) applied to patients recovering from recent open cardio-thoracic surgery (CTS).
Design- Prospective, double-blind, 14-day randomised-controlled trial.
Participants and setting- 60 inpatients recovering from recent CTS and early admitted to a pulmonary rehabilitation program.
Interventions- Chest physiotherapy plus EMT with a resistive load of 30 cm H2O for active group and chest physiotherapy plus EMT with a sham load for control group.
Measures- Changes in maximal expiratory pressure (MEP) was considered as primary outcome, while maximal inspiratory pressures (MIP), dynamic and static lung volumes, oxygenation, perceived symptoms of dyspnoea, thoracic pain and well being (evaluated by visual analogic scale-VAS) and general health status were considered secondary outcomes.
Results- All outcomes recorded showed significant improvements in both groups; however, the change of MEP (+34.2 mmHg, p<0.001 and +26.1%, p<0.001 for absolute and % of predicted, respectively) was significantly higher in Active group. Also VAS-dyspnoea improved faster and more significantly (p<0.05) at day 12 and 14 in Active group when compared with Control. The drop out rate was 6%, without differences between groups.
Conclusions- In patients recovering from recent CTS specific EMT by Respilift™ is feasible and effective
Respiratory muscle training positively affects vasomotor response in young healthy women
Vasomotor response is related to the capacity of the vessel to maintain vascular tone within a narrow range. Two main control mechanisms are involved: the autonomic control of the sympathetic neural drive (global control) and the endothelial smooth cells capacity to respond to mechanical stress by releasing vasoactive factors (peripheral control). The aim of this study was to evaluate the effects of respiratory muscle training (RMT) on vasomotor response, assessed by flow-mediated dilation (FMD) and heart rate variability, in young healthy females. The hypothesis was that RMT could enhance the balance between sympa- thetic and parasympathetic neural drive and reduce vessel shear stress. Thus, twenty-four women were randomly assigned to either RMT or SHAM group. Maximal inspiratory mouth pressure and maximum voluntary ventilation were utilized to assess the effectiveness of the RMT program, which consisted of three sessions of isocapnic hyperventilation/ week for eight weeks, (twenty-four training sessions). Heart rate variability assessed autonomic bal- ance, a global factor regulating the vasomotor response. Endothelial function was deter- mined by measuring brachial artery vasodilation normalized by shear rate (%FMD/SR). After RMT, but not SHAM, maximal inspiratory mouth pressure and maximum voluntary ventilation increased significantly (+31% and +16%, respectively). Changes in heart rate variability were negligible in both groups. Only RMT exhibited a significant increase in % FMD/SR (+45%; p\u3c0.05). These data suggest a positive effect of RMT on vasomotor response that may be due to a reduction in arterial shear stress, and not through modulation of sympatho-vagal balance
Lifestyle intervention on body weight and physical activity in patients with breast cancer can reduce the risk of death in obese women: The EMILI study
Background obesity and sedentary lifestyle have been shown to negatively affect survival in breast cancer (BC). The purpose of this study was to test the efficacy of a lifestyle intervention on body mass index (BMI) and physical activity (PA) levels among BC survivors in Modena, Italy, in order to show an outcome improvement in obese and overweight patients. Methods: This study is a single-arm experimental design, conducted between November 2009 and May 2016 on 430 women affected by BC. Weight, BMI, and PA were assessed at baseline, at 12 months, and at the end of the study. Survival curves were estimated among normal, overweight, and obese patients. Results: Mean BMI decreased from baseline to the end of the study was equal to 2.9% (p = 0.065) in overweight patients and 3.3% in obese patients (p = 0.048). Mean PA increase from baseline to the end of the study was equal to 125% (p < 0.001) in normal patients, 200% (p < 0.001) in overweight patients and 100% (p < 0.001) in obese patients. After 70 months of follow-up, the 5-year overall survival (OS) rate was 96%, 96%, and 93%, respectively in normal, obese, and overweight patients. Overweight patients had significantly worse OS than normal ones (HR = 3.69, 95%CI = 1.82–4.53 p = 0.027) whereas no statistically significant differences were seen between obese and normal patients (HR 2.45, 95%CI = 0.68–8.78, p = 0.169). Conclusions: A lifestyle intervention can lead to clinically meaningful weight loss and increase PA in patients with BC. These results could contribute to improving the OS in obese patients compared to overweight ones
On the muon neutrino mass
During the runs of the PS 179 experiment at LEAR of CERN, we photographed an
event of antiproton-Ne absorption, with a complete pi+ -> mu+ ->e+ chain. From
the vertex of the reaction a very slow energy pi+ was emitted. The pi+ decays
into a mu+ and subsequently the mu+ decays into a positron. At the first decay
vertex a muon neutrino was emitted and at the second decay vertex an electron
neutrino and a muon antineutrino. Measuring the pion and muon tracks and
applying the momentum and energy conservation and using a classical statistical
interval estimator, we obtained an experimental upper limit for the muon
neutrino mass: m_nu < 2.2 MeV at a 90% confidence level. A statistical analysis
has been performed of the factors contributing to the square value of the
neutrino mass limit.Comment: 18 pages, 5 eps figure
In vivo and in vitro evidence that intrinsic upper- and lower-limb skeletal muscle function is unaffected by ageing and disuse in oldest-old humans
Aim: To parse out the impact of advanced ageing and disuse on skeletal
muscle function, we utilized both in vivo and in vitro techniques to comprehensively
assess upper- and lower-limb muscle contractile properties in
8 young (YG; 25 6 years) and 8 oldest-old mobile (OM; 87 5 years)
and 8 immobile (OI; 88 4 years) women.
Methods: In vivo, maximal voluntary contraction (MVC), electrically
evoked resting twitch force (RT), and physiological cross-sectional area
(PCSA) of the quadriceps and elbow flexors were assessed. Muscle biopsies
of the vastus lateralis and biceps brachii facilitated the in vitro assessment
of single fibre-specific tension (Po).
Results: In vivo, compared to the young, both the OM and OI exhibited
a more pronounced loss of MVC in the lower limb [OM (60%) and OI
(75%)] than the upper limb (OM = 51%; OI = 47%). Taking into
account the reduction in muscle PCSA (OM = 10%; OI = 18%), only
evident in the lower limb, by calculating voluntary muscle-specific force,
the lower limb of the OI (40%) was more compromised than the OM
(13%). However, in vivo, RT in both upper and lower limbs (approx.
9.8 N m cm
2) and Po (approx. 123 mN mm
2), assessed in vitro, implies
preserved intrinsic contractile function in all muscles of the oldest-old and
were well correlated (r = 0.81).
Conclusion: These findings suggest that in the oldest-old, neither
advanced ageing nor disuse, per se, impacts intrinsic skeletal muscle function,
as assessed in vitro. However, in vivo, muscle function is attenuated
by age and exacerbated by disuse, implicating factors other than skeletal
muscle, such as neuromuscular control, in this diminution of function.
Keywords in vitro, in vivo, oldest-old, sarcopeni
Personalized Systemic Therapies in Hereditary Cancer Syndromes
Hereditary cancer syndromes are inherited disorders caused by germline pathogenic variants (PVs) that lead to an increased risk of developing certain types of cancer, frequently at an earlier age than in the rest of the population. The germline PVs promote cancer development, growth and survival, and may represent an ideal target for the personalized treatment of hereditary tumors. PARP inhibitors for the treatment of BRCA and PALB2-associated tumors, immune checkpoint inhibitors for tumors associated with the Lynch Syndrome, HIF-2α inhibitor in the VHL-related cancers and, finally, selective RET inhibitors for the treatment of MEN2-associated medullary thyroid cancer are the most successful examples of how a germline PVs can be exploited to develop effective personalized therapies and improve the outcome of these patients. The present review aims to describe and discuss the personalized systemic therapies for inherited cancer syndromes that have been developed and investigated in clinical trials in recent decades
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