Kinetics of Surfactant Adsorption at Fluid/Fluid Interfaces: Non-ionic Surfactants

We present a model treating the kinetics of adsorption of soluble surface-active molecules at the interface between an aqueous solution and another fluid phase. The model accounts for both the diffusive transport inside the solution and the kinetics taking place at the interface using a free-energy formulation. In addition, it offers a general method of calculating dynamic surface tensions. Non-ionic surfactants are shown, in general, to undergo a diffusion-limited adsorption, in accord with experimental findings.Comment: 6 pages, 3 figures, see also cond-mat/960814

Quantum tomography via equidistant states

We study the possibility of performing quantum state tomography via equidistant states. This class of states allows us to propose a non-symmetric informationally complete POVM based tomographic scheme. The scheme is defined for odd dimensions and involves an inversion which can be analytically carried out by Fourier transform

Boundary-layer friction in midlatitude cyclone

Results from an idealized three-dimensional baroclinic life-cycle model are interpreted in a potential vorticity (PV) framework to identify the physical mechanisms by which frictional processes acting in the atmospheric boundary layer modify and reduce the baroclinic development of a midlatitude storm. Considering a life cycle where the only non-conservative process acting is boundary-layer friction, the rate of change of depth-averaged PV within the boundary layer is governed by frictional generation of PV and the flux of PV into the free troposphere. Frictional generation of PV has two contributions: Ekman generation, which is directly analogous to the well-known Ekman-pumping mechanism for barotropic vortices, and baroclinic generation, which depends on the turning of the wind in the boundary layer and low-level horizontal temperature gradients. It is usually assumed, at least implicitly, that an Ekman process of negative PV generation is the mechanism whereby friction reduces the strength and growth rates of baroclinic systems. Although there is evidence for this mechanism, it is shown that baroclinic generation of PV dominates, producing positive PV anomalies downstream of the low centre, close to developing warm and cold fronts. These PV anomalies are advected by the large-scale warm conveyor belt flow upwards and polewards, fluxed into the troposphere near the warm front, and then advected westwards relative to the system. The result is a thin band of positive PV in the lower troposphere above the surface low centre. This PV is shown to be associated with a positive static stability anomaly, which Rossby edge wave theory suggests reduces the strength of the coupling between the upper- and lower-level PV anomalies, thereby reducing the rate of baroclinic development. This mechanism, which is a result of the baroclinic dynamics in the frontal regions, is in marked contrast with simple barotropic spin-down ideas. Finally we note the implications of these frictionally generated PV anomalies for cyclone forecasting

Investigating diet as the source of tetrodotoxin in Pleurobranchaea maculata

The origin of tetrodotoxin (TTX) is highly debated; researchers have postulated either an endogenous or exogenous source with the host accumulating TTX symbiotically or via food chain transmission. The aim of this study was to determine whether the grey side-gilled sea slug (Pleurobranchaea maculata) could obtain TTX from a dietary source, and to attempt to identify this source through environmental surveys. Eighteen non-toxic P. maculata were maintained in aquariums and twelve were fed a TTX-containing diet. Three P. maculata were harvested after 1 h, 24 h, 17 days and 39 days and TTX concentrations in their stomach, gonad, mantle and remaining tissue/fluids determined using liquid chromatography-mass spectrometry. Tetrodotoxin was detected in all organs/tissue after 1 h with an average uptake of 32%. This decreased throughout the experiment (21%, 15% and 9%, respectively). Benthic surveys at sites with dense populations of toxic P. maculata detected very low or no TTX in other organisms. This study demonstrates that P. maculata can accumulate TTX through their diet. However, based on the absence of an identifiable TTX source in the environment, in concert with the extremely high TTX concentrations and short life spans of P. maculata, it is unlikely to be the sole TTX source for this species

Association Between Method of Prescribing and Primary Nonadherence to Dermatologic Medication in an Urban Hospital Population

Importance Prescription underuse is associated with poorer clinical outcomes. A significant proportion of underuse is owing to primary nonadherence, defined as the rate at which patients fail to fill and pick up new prescriptions. Although electronic prescribing increases coordination of care and decreases errors, its effect on primary nonadherence is less certain. Objectives To analyze factors associated with primary nonadherence to dermatologic medications and study whether electronic prescribing affects rates of primary nonadherence. Design, Setting, and Participants A retrospective review of medical records was conducted from January 1, 2011, to December 31, 2013, among a cohort of new patients prescribed dermatologic medications at a single, urban, safety-net hospital outpatient dermatology clinic. Main Outcomes and Measures The primary outcome was the overall rate of primary nonadherence, defined as filling and picking up all prescribed medications within a 1-year period, and the difference in primary nonadherence between patients who received electronic prescriptions and those who received paper prescriptions. Secondary outcomes included the association of primary nonadherence with sex, age, relationship status, primary language, race/ethnicity, and number of prescriptions. Results A total of 4318 prescriptions were written for 2496 patients (mean [SD] age, 47.7 [13.2] years; 849 men and 1647 women). The overall rate of primary nonadherence was 31.6% (n = 788). Based on multivariable analysis, the risk of primary nonadherence was 16 percentage points lower among patients given an electronic prescription (15.2%) than patients given a paper prescription (31.5%). Primary nonadherence decreased with age (<30 y, 38.9%; 30-49 y, 35.3%; and 50-69 y, 26.3%), and then increased in elderly patients 70 years and older (31.9%). Of patients who were given 1, 2, 3, 4, or 5 prescriptions, rates of primary nonadherence were 33.1%, 28.8%, 26.4%, 39.8%, and 38.1%, respectively. Primary nonadherence decreased with age but then increased in elderly patients. Patients identifying English as their primary language had the highest rate of primary nonadherence (33.9%) compared with Spanish (29%) or other speakers (20.4%). Conclusions and Relevance Compared with paper prescriptions, electronic prescriptions were associated with less primary nonadherence. Number of prescriptions, language, race/ethnicity, and age were associated with increased rates of primary nonadherence. Efforts must be made to understand why primary nonadherence occurs, identify patients prone to primary nonadherence, and simplify medication regimens to maximize adherence and quality of care

Transcriptional Activation of Antioxidants May Compensate for Selenoprotein Deficiences in \u3ci\u3eAmblyomma maculatum\u3c/i\u3e (Acari: Ixodidae) Injected With \u3ci\u3eselK\u3c/i\u3e- or \u3ci\u3eselM\u3c/i\u3e- dsRNA

The Gulf‐Coast tick, Amblyomma maculatum, possesses an elaborate set of selenoproteins, which prevent the deleterious effects from oxidative stress that would otherwise occur during feeding. In the current work, we examined the role of selenoprotein K (SelK) and selenoprotein M (SelM) in feeding A. maculatum by bioinformatics, transcriptional gene expression, RNA interference and antioxidant assays. The transcriptional expression of SelK did not vary significantly in salivary glands or midguts throughout the bloodmeal. However, there was a 58‐fold increase in transcript levels of SelM in tick midguts. Ticks injected with selK‐dsRNA or selM‐dsRNA did not reveal any observable differences in egg viability but oviposition was reduced. Surprisingly, salivary antioxidant activity was higher in selenoprotein knockouts compared with controls, which is probably the result of compensatory transcriptional expression of genes involved in combating reactive oxygen species. In fact, quantitative real‐time PCR data suggest that the transcriptional expression of catalase increased in ticks injected with selM‐double‐stranded RNA. Additionally, the transcriptional expression of selN decreased ∼90% in both SelK/SelM knockdowns. These data indicate that SelK and SelM are salivary antioxidants but are not essential for tick survival or reproduction and are compensated by other antioxidant systems

Detecting Hidden Differences via Permutation Symmetries

We present a method for describing and characterizing the state of N particles that may be distinguishable in principle but not in practice due to experimental limitations. The technique relies upon a careful treatment of the exchange symmetry of the state among experimentally accessible and experimentally inaccessible degrees of freedom. The approach we present allows a new formalisation of the notion of indistinguishability and can be implemented easily using currently available experimental techniques. Our work is of direct relevance to current experiments in quantum optics, for which we provide a specific implementation.Comment: 8 pages, 1 figur