Dynamically broken symmetry in periodically gated quantum dots: Charge accumulation and dc-current

Time-dependent electron transport through a quantum dot and double quantum dot systems in the presence of polychromatic external periodic quantum dot energy-level modulations is studied within the time evolution operator method for a tight-binding Hamiltonian. Analytical relations for the dc-current flowing through the system and the charge accumulated on a quantum dot are obtained for the zero-temperature limit. It is shown that in the presence of periodic perturbations the sideband peaks of the transmission are related to combination frequencies of the applied modulations. For a double quantum dot system under the influence of polychromatic perturbations the quantum pump effect is studied in the absence of source-drain and static bias voltages. In the presence of spatial symmetry the charge is pumped through the system due to broken generalized parity symmetry.Comment: 10 pages, 7 figures, to appear in UJP (Ukr.J.Phys.

Can the UNAIDS 90-90-90 target be achieved? A systematic analysis of national HIV treatment cascades

Background In 2014, the Joint United Nations Programme on HIV and AIDS (UNAIDS) and partners set the ‘90-90-90 targets’; aiming to diagnose 90% of all HIV positive people, provide antiretroviral therapy (ART) for 90% of those diagnosed and achieve viral suppression for 90% of those treated, by 2020. This results in 81% of all HIV positive people on treatment and 73% of all HIV positive people achieving viral suppression. We aimed to analyse how effective national HIV treatment programmes are at meeting these targets, using HIV care continuums or cascades. Methods We searched for HIV treatment cascades for 196 countries in published papers, conference presentations, UNAIDS databases and national reports. Cascades were constructed using reliable, generalisable, recent data from national, cross-sectional and longitudinal study cohorts. Data were collected for four stages; total HIV positive people, diagnosed, on treatment and virally suppressed. The cascades were categorised as complete (four stages) or partial (3 stages), and analysed for ‘break points’ defined as a drop >10% in coverage between consecutive 90-90-90 targets. Results 69 country cascades were analysed (32 complete, 37 partial). Diagnosis (target one—90%) ranged from 87% (the Netherlands) to 11% (Yemen). Treatment coverage (target two—81% on ART) ranged from 71% (Switzerland) to 3% (Afghanistan). Viral suppression (target three—73% virally suppressed) was between 68% (Switzerland) and 7% (China). Conclusions No country analysed met the 90-90-90 targets. Diagnosis was the greatest break point globally, but the most frequent key break point for individual countries was providing ART to those diagnosed. Large disparities were identified between countries. Without commitment to standardised reporting methodologies, international comparisons are complex

Accelerating MCMC via Parallel Predictive Prefetching

We present a general framework for accelerating a large class of widely used Markov chain Monte Carlo (MCMC) algorithms. Our approach exploits fast, iterative approximations to the target density to speculatively evaluate many potential future steps of the chain in parallel. The approach can accelerate computation of the target distribution of a Bayesian inference problem, without compromising exactness, by exploiting subsets of data. It takes advantage of whatever parallel resources are available, but produces results exactly equivalent to standard serial execution. In the initial burn-in phase of chain evaluation, it achieves speedup over serial evaluation that is close to linear in the number of available cores

Coulomb blockade effects in driven electron transport

We study numerically the influence of strong Coulomb repulsion on the current through molecular wires that are driven by external electromagnetic fields. The molecule is described by a tight-binding model whose first and last site is coupled to a respective lead. The leads are eliminated within a perturbation theory yielding a master equation for the wire. The decomposition into a Floquet basis enables an efficient treatment of the driving field. For the electronic excitations in bridged molecular wires, we find that strong Coulomb repulsion significantly sharpens resonance peaks which broaden again with increasing temperature. By contrast, Coulomb blockade has only a small influence on effects like non-adiabatic electron pumping and coherent current suppression.Comment: 9 pages, 7 figures. Added a plot for temperature dependence of resonance peaks. Published versio

Educational differences in all-cause mortality by marital status

Using life table measures, we compare educational differentials in all-cause mortality at ages 40 to 70 in Bulgaria to those in Finland and the United States. Specifically, we assess whether the relationship between education and mortality is modified by marital status. Although high education and being married are associated with lower mortality in all three countries, absolute educational differences tend to be smaller among married than unmarried individuals. Absolute differentials by education are largest for Bulgarian men, but in relative terms educational differences are smaller among Bulgarian men than in Finland and the U.S. Among women, Americans experience the largest education-mortality gradients in both relative and absolute terms. Our results indicate a particular need to tackle health hazards among poorly educated men in countries in transition.all-cause mortality, Bulgaria, educational differentials, Finland, life table measures, marital status, USA

Non-equilibrium dynamics of a system with Quantum Frustration

Using flow equations, equilibrium and non-equilibrium dynamics of a two-level system are investigated, which couples via non-commuting components to two independent oscillator baths. In equilibrium the two-level energy splitting is protected when the TLS is coupled symmetrically to both bath. A critical asymmetry angle separates the localized from the delocalized phase. On the other hand, real-time decoherence of a non-equilibrium initial state is for a generic initial state faster for a coupling to two baths than for a single bath.Comment: 22 pages, 9 figure

Extending the Grazing Season With Turnips

A comparison of the actual feeding costs on 86 typical Swiss dairy farms confirmed that the production of hay and grass silage is very expensive with costs from the field to intake in the range of 20-25 Euro cents/kg of dry matter (DM). Options to extend the grazing season for dairy cows in the late autumn and early winter, and hence reduce winter feeding costs, would therefore be welcome (Penrose et al., 1996). The aim of the study was to compare the DM production potential of summer-seeded turnips with other brassicas and Italian ryegrass and to test whether dairy cows can utilize the bulbs of turnips efficiently

Chirality of pollutants—effects on metabolism and fate

In most cases, enantiomers of chiral compounds behave differently in biochemical processes. Therefore, the effects and the environmental fate of the enantiomers of chiral pollutants need to be investigated separately. In this review, the different fates of the enantiomers of chiral phenoxyalkanoic acid herbicides, acetamides, organochlorines, and linear alkylbenzenesulfonates are discussed. The focus lies on biological degradation, which may be enantioselective, in contrast to non-biotic conversions. The data show that it is difficult to predict which enantiomer may be enriched and that accumulation of an enantiomer is dependent on the environmental system, the species, and the organ. Racemization and enantiomerization processes occur and make interpretation of the data even more complex. Enantioselective degradation implies that the enzymes involved in the conversion of such compounds are able to differentiate between the enantiomers. "Enzyme pairs” have evolved which exhibit almost identical overall folding. Only subtle differences in their active site determine their enantioselectivities. At the other extreme, there are examples of non-homologous "enzyme pairs” that have developed through convergent evolution to enantioselectively turn over the enantiomers of a chiral compound. For a better understanding of enantioselective reactions, more detailed studies of enzymes involved in enantioselective degradation need to be performe

Bacterial β-peptidyl aminopeptidases: on the hydrolytic degradation of β-peptides

The special chemical and biological features of β-peptides have been investigated intensively during recent years. Many studies emphasize the restricted biodegradability and the high metabolic stability of this class of compounds. β-Peptidyl aminopeptidases form the first family of enzymes that hydrolyze a variety of short β-peptides and β-amino-acid-containing peptides. All representatives of this family were isolated from Gram-negative bacteria. The substrate specificities of the peptidases vary greatly, but the enzymes have common structural properties, and a similar reaction mechanism can be expected. This review gives an overview on the β-peptidyl aminopeptidases with emphasis on their biochemical and structural properties. Their possible physiological function is discussed. Functionally and structurally related enzymes are compared to the β-peptidyl aminopeptidase

Ectrin Ear Tags for Horn Fly Control on Range Beef Cattle

Ectrin ear tags are insecticide-impregnated with the active ingredient fenvalerate (8%). They are approved for use on lactating dairy cattle, beef cattle and calves. Each time an animal turns on tosses its head, a layer of Ectrin is rubbed or falls off onto the animal. As one insecticide layter is rubbed off, another forms. This action continues for the life of the tag. Advantages to this type of horn fly control are tagging is quick and easy using the All-Flex specially designed pliers, dampness or rain has little effect on efficacy, and the fly control reservoir is carried and used by each treated animal. A random sample of 10 animals from each herd was counted using binoculars and looking out of a pickup window. Results are presented as an average number of horn flies/side of these 10 animals. An equal number of untreated or control animals was counted from a herd near the treated herd at nearly the same time. Problems of last tags or infected ears due to the tags were minimal