102 research outputs found
Large deviations of currents in diffusions with reflective boundaries
We study the large deviations of current-type observables defined for Markov
diffusion processes evolving in smooth bounded regions of with
reflections at the boundaries. We derive for these the correct boundary
conditions that must be imposed on the spectral problem associated with the
scaled cumulant generating function, which gives, by Legendre transform, the
rate function characterizing the likelihood of current fluctuations. Two
methods for obtaining the boundary conditions are presented, based on the
diffusive limit of random walks and on the Feynman--Kac equation underlying the
evolution of generating functions. Our results generalize recent works on
density-type observables, and are illustrated for an -particle single-file
diffusion on a ring, which can be mapped to a reflected -dimensional
diffusion.Comment: 24 pages, 2 figure
Time scales and exponential trends to equilibrium: Gaussian model problems
We review results on the exponential convergence of multi- dimensional Ornstein-Uhlenbeck processes and discuss related notions of characteristic timescales with concrete model systems. We focus, on the one hand, on exit time distributions and provide ecplicit expressions for the exponential rate of the distribution in the small noise limit. On the other hand, we consider relaxation timescales of the process to its equi- librium measured in terms of relative entropy and discuss the connection with exit probabilities. Along these lines, we study examples which il- lustrate specific properties of the relaxation and discuss the possibility of deriving a simulation-based, empirical definition of slow and fast de- grees of freedom which builds upon a partitioning of the relative entropy functional in conjuction with the observed relaxation behaviour
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BoBBLE: ocean-atmosphere interaction and its impact on the South Asian monsoon
The Bay of Bengal (BoB) plays a fundamental role in controlling the weather systems that make up the South Asian summer monsoon system. In particular,the southern BoB has cooler sea surface temperature (SST) that influence ocean-atmosphere interaction and impact on the monsoon. Compared to the southeast, the southwestern BoB is cooler, more saline, receives much less rain, and is influenced by the Summer Monsoon Current(SMC). To examine the impact of these features on the monsoon, the BoB Boundary Layer Experiment (BoBBLE) was jointly undertaken by India and the UK during June–July 2016. Physical and bio-geochemical observations were made using a CTD, five ocean gliders, a uCTD, a VMP, two ADCPs, Argo floats, drifting buoys, meteorological sensors and upper air radiosonde balloons. The observations were made along a zonal section at 8◦N between 85.3◦E and 89◦E with a 10-day time series at 89◦E, 8◦N. This paper presents the new observed features of the southern BoB from the BoBBLE field program, supported by satellite data. Key results from the BoBBLE field campaign show the Sri Lanka Dome and the SMC in different stages of their seasonal evolution and two freshening events during which salinity decreased in the upper layer leading to the formation of thick barrier layers. BoBBLE observations were taken during a suppressed phase of the intraseasonal oscillation; they captured in detail the warming of the ocean mixed layer and preconditioning of the atmosphere to convection
Paramagnetic limiting of the upper critical field of the layered organic superconductor
We report detailed measurements of the interlayer magnetoresistance of the
layered organic superconductor for temperatures
down to 0.5 K and fields up to 30 tesla. The upper critical field is determined
from the resistive transition for a wide range of temperatures and field
directions. For magnetic fields parallel to the layers, the upper critical
field increases approximately linearly with decreasing temperature. The upper
critical field at low temperatures is compared to the Pauli paramagnetic limit,
at which singlet superconductivity should be destroyed by the Zeeman splitting
of the electron spins. The measured value is comparable to a value for the
paramagnetic limit calculated from thermodynamic quantities but exceeds the
limit calculated from BCS theory. The angular dependence of the upper critical
field shows a cusp-like feature for fields close to the layers, consistent with
decoupled layers.Comment: 16 pages 5 figure
Year in review in Intensive Care Medicine 2010: III. ARDS and ALI, mechanical ventilation, noninvasive ventilation, weaning, endotracheal intubation, lung ultrasound and paediatrics
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Pleiotropy among common genetic loci identified for cardiometabolic disorders and C-reactive protein.
Pleiotropic genetic variants have independent effects on different phenotypes. C-reactive protein (CRP) is associated with several cardiometabolic phenotypes. Shared genetic backgrounds may partially underlie these associations. We conducted a genome-wide analysis to identify the shared genetic background of inflammation and cardiometabolic phenotypes using published genome-wide association studies (GWAS). We also evaluated whether the pleiotropic effects of such loci were biological or mediated in nature. First, we examined whether 283 common variants identified for 10 cardiometabolic phenotypes in GWAS are associated with CRP level. Second, we tested whether 18 variants identified for serum CRP are associated with 10 cardiometabolic phenotypes. We used a Bonferroni corrected p-value of 1.1×10-04 (0.05/463) as a threshold of significance. We evaluated the independent pleiotropic effect on both phenotypes using individual level data from the Women Genome Health Study. Evaluating the genetic overlap between inflammation and cardiometabolic phenotypes, we found 13 pleiotropic regions. Additional analyses showed that 6 regions (APOC1, HNF1A, IL6R, PPP1R3B, HNF4A and IL1F10) appeared to have a pleiotropic effect on CRP independent of the effects on the cardiometabolic phenotypes. These included loci where individuals carrying the risk allele for CRP encounter higher lipid levels and risk of type 2 diabetes. In addition, 5 regions (GCKR, PABPC4, BCL7B, FTO and TMEM18) had an effect on CRP largely mediated through the cardiometabolic phenotypes. In conclusion, our results show genetic pleiotropy among inflammation and cardiometabolic phenotypes. In addition to reverse causation, our data suggests that pleiotropic genetic variants partially underlie the association between CRP and cardiometabolic phenotypes
Targeted pH switched europium complexes monitoring receptor internalisation in living cells
We report the design and evaluation of pH responsive luminescent europium(III) probes that allow conjugation to targeting vectors to monitor receptor internalisation in cells. The approach adopted here can be used to tag proteins selectively and to monitor uptake into more acidic organelles, thereby enhancing the performance of time-resolved internalisation assays that require pH monitoring in real time
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