Work and heat probability distribution of an optically driven Brownian particle: Theory and experiments

We analyze the equations governing the evolution of distributions of the work and the heat exchanged with the environment by a manipulated stochastic system, by means of a compact and general derivation. We obtain explicit solutions for these equations for the case of a dragged Brownian particle in a harmonic potential. We successfully compare the resulting predictions with the outcomes of experiments, consisting in dragging a micron-sized colloidal particle through water with a laser trap

Influence of rotational force fields on the determination of the work done on a driven Brownian particle

For a Brownian system the evolution of thermodynamic quantities is a stochastic process. In particular, the work performed on a driven colloidal particle held in an optical trap changes for each realization of the experimental manipulation, even though the manipulation protocol remains unchanged. Nevertheless, the work distribution is governed by established laws. Here, we show how the measurement of the work distribution is influenced by the presence of rotational, i.e. nonconservative, radiation forces. Experiments on particles of different materials show that the rotational radiation forces, and therefore their effect on the work distributions, increase with the particle refractive index.Comment: 12 pages, 4 figure

Stratonovich-to-Ito transition in noisy systems with multiplicative feedback

Cataloged from PDF version of article.Intrinsically noisy mechanisms drive most physical, biological and economic phenomena. Frequently, the system's state influences the driving noise intensity (multiplicative feedback). These phenomena are often modelled using stochastic differential equations, which can be interpreted according to various conventions (for example, Ito calculus and Stratonovich calculus), leading to qualitatively different solutions. Thus, a stochastic differential equation-convention pair must be determined from the available experimental data before being able to predict the system's behaviour under new conditions. Here we experimentally demonstrate that the convention for a given system may vary with the operational conditions: we show that a noisy electric circuit shifts from obeying Stratonovich calculus to obeying Ito calculus. We track such a transition to the underlying dynamics of the system and, in particular, to the ratio between the driving noise correlation time and the feedback delay time. We discuss possible implications of our conclusions, supported by numerics, for biology and economics

Direct UV observations of the circumstellar envelope of alpha Orionis

Observations were made in the IUE LWP camera, low dispersion mode, with alpha Ori being offset various distances from the center of the Long Wavelength Large Aperture along its major axis. Signal was acquired at all offset positions and is comprised of unequal components of background/dark counts, telescope-scattered light, and scattered light emanating from the extended circumstellar shell. The star is known from optical and infrared observations to possess an extended, arc-minute sized, shell of cool material. Attempts to observe this shell with the IUE are described, although the deconvolution of the stellar signal from the telescope scattered light requires further calibration effort

Formation and evolution of clumpy tidal tails around globular clusters

We present some results of numerical simulations of a globular cluster orbiting in the central region of a triaxial galaxy on a set of 'loop' orbits. Tails start forming after about a quarter of the globular cluster orbital period and develop, in most cases, along the cluster orbit, showing clumpy substructures as observed, for example, in Palomar 5. If completely detectable, clumps can contain about 7,000 solar masses each, i.e. about 10% of the cluster mass at that epoch. The morphology of tails and clumps and the kinematical properties of stars in the tails are studied and compared with available observational data. Our finding is that the stellar velocity dispersion tends to level off at large radii, in agreement to that found for M15 and Omega Centauri.Comment: LaTeX 2e, uses AASTeX v5.x, 40 pages with 18 figures. Submitted to The Astronomical Journa

Tocilizumab in MOG-antibody spectrum disorder: a case report

Background: Myelin oligodendrocyte glycoprotein antibody-related spectrum disorders (MOG-SD) are a heterogeneous group of inflammatory demyelinating diseases of the central nervous system, usually responsive to conventional immunosuppressive therapies. However, knowledge about treatment of non-responder patients is scarce. Methods: We report on a 20-year-old MOG-SD patient who experienced clinical deterioration despite rituximab-induced B-cell depletion. Results: Rescue therapy with tocilizumab (TCZ) prevented further relapses, with reduction of spinal-cord load on MRI, and a remarkable reduction of disability at the two-year follow-up. Conclusion: Our observations suggest that TCZ could induce clinico-radiologic improvements, which make it as an option for the treatment of MOG-SD

Evaluation of reflux following sleeve gastrectomy and one anastomosis gastric bypass: 1-year results from a randomized open-label controlled trial

Background: Recent reports have demonstrated that de novo reflux and worsening of pre-existing symptoms occur after SG; concerns are still expressed about the risk of symptomatic biliary reflux gastritis and oesophagitis. The aim of our study was to investigate and compare the rate of postoperative acid and non-acid reflux following Mini-/One anastomosis gastric bypass (MGB/OAGB) and laparoscopic sleeve gastrectomy (LSG). Study design: A prospective randomized open-label, controlled trial registered on clinicaltrial.gov (NCT number: NCT02987673) has been carried out to evaluate esophagogastric junction exposure to reflux in the first year after MGB/OAGB and LSG using high impedance manometry, endoscopy, and a validated questionnaire. Results: A total of 58 individuals were eventually enrolled in this trial and represented the per-protocol population (n = 28 MGB/OAGB, n = 30 LSG). No difference was found between the two groups in terms of demographic characteristics, PAGI-SYM score, acid exposure time percent of the esophagus (AET%), esophagitis, and other HRiM and MII-pH data at baseline. Comparing MII-pH outcomes of the two groups, AET% resulted significantly higher after LSG at 12 months. Endoscopic findings showed a significant increase of esophagitis ≥ B in the LSG group after 1 year; postoperative esophagitis ≥ B resulted also significantly worsened after LSG when compared to MGB/OAGB. Conclusion: Since AET% and rate of esophagitis are significantly higher after LSG when compared to MGB/OAGB, this procedure should be preferred in case of preoperative subclinical reflux or low grade (A) esophagitis

Diabetes and pancreatic cancer-a dangerous liaison relying on carbonyl stress

Both type 2 (T2DM) and type 1 (T1DM) diabetes mellitus confer an increased risk of pancreatic cancer in humans. The magnitude and temporal trajectory of the risk conferred by the two forms of diabetes are similar, suggesting a common mechanism. Carbonyl stress is a hallmark of hyperglycemia and dyslipidemia, which accompanies T2DM, prediabetes, and obesity. Accumulating evidence demonstrates that diabetes promotes pancreatic ductal adenocarcinoma (PDAC) in experimental models of T2DM, a finding recently confirmed in a T1DM model. The carbonyl stress markers advanced glycation end-products (AGEs), the levels of which are increased in diabetes, were shown to markedly accelerate tumor development in a mouse model of Kras-driven PDAC. Consistently, inhibition of AGE formation by trapping their carbonyl precursors (i.e., reactive carbonyl species, RCS) prevented the PDAC-promoting effect of diabetes. Considering the growing attention on carbonyl stress in the onset and progression of several cancers, including breast, lung and colorectal cancer, this review discusses the mechanisms by which glucose and lipid imbalances induce a status of carbonyl stress, the oncogenic pathways activated by AGEs and their precursors RCS, and the potential use of carbonyl-scavenging agents and AGE inhibitors in PDAC prevention and treatment, particularly in high-risk diabetic individuals