The motion of the particles is described by a Fick-Jakobs kinetic equation in which the presence of boundaries is
modeled by means of an entropic potential. The cases of a flashing ratchet, a two-state model, and a ratchet under the influence of a temperature gradient are analyzed in detail. We show the emergence of a strong cooperativity between the inherent rectification CYT387 of the ratchet mechanism and the entropic bias of the fluctuations caused by spatial confinement. Net particle transport may take place in situations where none of those mechanisms leads to rectification when acting individually. The combined rectification mechanisms may lead to bidirectional transport and to new routes to segregation phenomena. Confined Brownian ratchets could be used to control transport in mesostructures and to engineer new and more efficient devices for transport at the nanoscale. (C) 2013 AIP Publishing LLC.”
“In the late 1920s, two forms of data plot were used to analyze the current-voltage (i-V) data obtained in experiments on cold field electron emission (CFE). Millikan-Lauritsen (ML) plots have the form
[lni versus 1/V]; Fowler-Nordheim (FN) plots have the form [lni/V-2 versus 1/V]. In both cases common selleck inhibitor logarithms may be used instead. For historical reasons, it has become customary to use FN plots; but recent mathematical developments in CFE theory made these historical reasons less valid than they formerly were. ML plots are in fact easier to understand and use, and are more flexible when it is wanted to make corrections for all
physical sources of voltage dependence in the data, or to estimate uncertainties selleck products in derived parameter values when the precise forms of voltage dependences are not known. This paper summarizes historical and recent background and argues that ML plots should now replace FN plots as the basic method of analyzing CFE i-V data (or related data involving current densities and/or fields). A formula for the interpretation of ML plot slopes is presented and discussed, and examples are given of its use. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3140602]“
“Abdominal pain with a discoloured dialysate in a patient on peritoneal dialysis (PD) is usually attributed to infective peritonitis. Although acute pancreatitis (AP) is not usually a complication of end-stage renal disease, some studies suggest an increased risk especially in patients on PD. We report a case of idiopathic AP in a 41-year-old female on PD who presented with abdominal pain, fever, vomiting and a clear dark dialysate. Initial diagnosis of PD-associated infective peritonitis was made but dialysate cultures proved negative. Serum amylase showed a mild rise and computed tomography revealed necrotising pancreatitis. No common risk factors for AP were identified and she was successfully treated with conservative therapy.