290 research outputs found
Steady-state composition of a two-component gas bubble growing in a liquid solution: self-similar approach
The paper presents an analytical description of the growth of a two-component
bubble in a binary liquid-gas solution. We obtain asymptotic self-similar time
dependence of the bubble radius and analytical expressions for the non-steady
profiles of dissolved gases around the bubble. We show that the necessary
condition for the self-similar regime of bubble growth is the constant,
steady-state composition of the bubble. The equation for the steady-state
composition is obtained. We reveal the dependence of the steady-state
composition on the solubility laws of the bubble components. Besides, the
universal, independent from the solubility laws, expressions for the
steady-state composition are obtained for the case of strong supersaturations,
which are typical for the homogeneous nucleation of a bubble.Comment: 12 pages, 2 figure
Dynamics of gas bubble growth in a supersaturated solution with Sievert's solubility law
This paper presents a theoretical description of diffusion growth of a gas
bubble after its nucleation in supersaturated liquid solution. We study systems
where gas molecules completely dissociate in the solvent into two parts, thus
making Sievert's solubility law valid. We show that the difference between
Henry's and Sievert's laws for chemical equilibrium conditions causes the
difference in bubble growth dynamics. Assuming that diffusion flux is steady we
obtain a differential equation on bubble radius. Bubble dynamics equation is
solved analytically for the case of homogeneous nucleation of a bubble, which
takes place at a significant pressure drop. We also obtain conditions of
diffusion flux steadiness. The fulfillment of these conditions is studied for
the case of nucleation of water vapor bubbles in magmatic melts.Comment: 22 pages, 3 figure
EVALUATION OF PRESCRIBING PATTERN OF FIXED DOSE COMBINATIONS OF ANTIHYPERTENSIVES AND ANTIDIABETIC AGENTS
  Objective: The objective of this research was to evaluate prescribing pattern of fixed dose combinations (FDCs) of antihypertensives and antidiabetic agents among patients of private hospitals.Methods: An observational study was carried out in the outpatient department of two hospitals. Data of patients being diagnosed with the symptoms of hypertension and diabetes were enrolled which mainly included information related to prescribe FDCs, i.e., antihypertensives and antidiabetics, respectively. Descriptive analysis of collected information was done which involved representation of demographical data, number of comorbidities, number of FDCs prescribed, and type of FDCs consequently.Results: Combination drug therapy was prescribed in maximum patients, which was enumerated as 93% among hypertensive patients and about 91% in diabetics. Average age of patients suffering more from hypertension was 64.5±18 years and that in case of diabetes sufferers was 54.5±18 years. The most frequent combination prescribed in hypertensive patients was of angiotensin receptor blocker (ARB) and calcium channel blocker (CCB) which were about 53%, and in diabetic patients, it was of biguanides and sulfonylureas about 63%. Comorbidity too was notified, and its estimation was 61% in hypertensive patients and 72% in diabetic patients, respectively.Conclusion: The study here demonstrates that the most often prescribed antihypertensive combination is of ARB and CCB, and subsequently for diabetes, the oral hypoglycemic combination is of biguanides and sulfonylureas. Most of FDCs contained medications of these two classes. Positive results were also observed in levels of blood pressure and glucose within the normal range
A super-Ohmic energy absorption in driven quantum chaotic systems
We consider energy absorption by driven chaotic systems of the symplectic
symmetry class. According to our analytical perturbative calculation, at the
initial stage of evolution the energy growth with time can be faster than
linear. This appears to be an analog of weak anti-localization in disordered
systems with spin-orbit interaction. Our analytical result is also confirmed by
numerical calculations for the symplectic quantum kicked rotor.Comment: 4 pages, 2 figure
Whitehead's varnish nasal pack
Whitehead's varnish is a little known but excellent nasal packing agent. We review available literature on the historical aspects and clinical use of Whitehead's varnish. Our personal experience with Whitehead's varnish is described, and we strongly recommend its use
On details of the thermodynamical derivation of the Ginsburg--Landau equations
We examine the procedure of thermodynamical derivation of the
Ginsburg--Landau equation for current, which is given unclear and contradictory
interpretations in existing textbooks. We clarify all steps of this procedure
and find as a consequence a limitation on the validity range of the
thermodynamic Ginsburg--Landau theory, which does not seem to be explicitely
stated up to now: we conclude that the thermodynamic theory is applicable only
to a superconducting specimen that is not a part of an external
current-carrying loop.Comment: 11 pages. Accepted for publication in 'Superconductor Science and
Technology
Switchable collective pinning of flux quanta using magnetic vortex arrays
We constructed a superconducting/ferromagnetic hybrid system in which the
ordering of the pinning potential landscape for flux quanta can be manipulated.
Flux pinning is induced by an array of magnetic nanodots in the magnetic vortex
state, and controlled by the magnetic history. This allows switching on and off
the collective pinning of the flux-lattice. In addition, we observed
field-induced superconductivity that originates from the annihilation of flux
quanta induced by the stray fields from the magnetic vortices.Comment: PDF file 18 pages including 5 figures, accepted for publication in
Phys. Rev.
Design and performance testing of quantitative real time PCR assays for influenza A and B viral load measurement
Background: The antiviral effect of anti-influenza drugs such as zanamivir may be demonstrated in patients as an increased rate of decline in viral load over a time course of treatment as compared with placebo. Historically this was measured using plaque assays, or Culture Enhanced Enzyme Linked Immunosorbent Assay (CE-ELISA). Objectives: to develop and characterise real time quantitative PCR (qPCR) assays to measure influenza A and B viral load in clinical samples, that offer improvements over existing methods, in particular virus infectivity assays. Study design: The dynamic range and robustness were established for the real time qPCR assays along with stability of the assay components. Cross validation of the real time PCR assays with CE-ELISA was performed by parallel testing of both serial dilutions of three different subtypes of cultured virus and a panel of influenza positive throat swab specimens. Results: the assays were specific for influenza A and B and the dynamic ranges were at least seven logs. The assay variability was within acceptable limits but increased towards the lower limit of quantification, which was 3.33 log10 viral cDNA copies/ml of virus transport medium (ten viral RNA copies/PCR). The components of the assay were robust enough to withstand extended storage and several freeze–thawcycles. For the real time PCR assays the limit of quantification was equivalent to the virus infectivity cut off, which equates to a 93-fold increase in sensitivity. Conclusion: Well characterised real time PCR assays offer significant improvements over the existing methods for measuring the viral load of strains of influenza A and B in clinical specimens
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