Path-integral Monte-Carlo simulations for electronic dynamics on molecular chains: I. Sequential hopping and super exchange

An improved real-time quantum Monte Carlo procedure is presented and applied to describe the electronic transfer dynamics along molecular chains. The model consists of discrete electronic sites coupled to a thermal environment which is integrated out exactly within the path integral formulation. The approach is numerically exact and its results reduce to known analytical findings (Marcus theory, golden rule) in proper limits. Special attention is paid to the role of superexchange and sequential hopping at lower temperatures in symmetric donor-bridge-acceptor systems. In contrast to previous approximate studies, superexchange turns out to play a significant role only for extremely high lying bridges where the transfer is basically frozen or for extremely low temperatures where for weaker dissipation a description in terms of rate constants is no longer feasible. For bridges with increasing length an algebraic decrease of the yield is found for short as well as for longer bridges. The approach can be extended to electronic systems with more complicated topologies including impurities and in presence of external time dependent forces.Comment: 14 pages, 9 figures submitted to the Journal of Chemical Physic

Age-dependent changes in autophosphorylation of alpha calcium/calmodulin dependent kinase II in hippocampus and amygdala after contextual fear conditioning

The hippocampus and amygdala are essential brain regions responsible for contextual fear conditioning (CFC). The autophosphorylation of alpha calciumcalmodulin kinase II (αCaMKII) at threonine-286 (T286) is a critical step 3 implicated in long-term potentiation (LTP), learning and memory. However, the changes in αCaMKII levels with aging and training in associated brain regions are not fully understood. Here, we studied how aging and training affect the levels of phosphorylated (T286) and proportion of phosphorylated:total αCaMKII in the hippocampus and amygdala. Young and aged mice, naïve (untrained) and trained in CFC, were analysed by immunohistochemistry for the levels of total and phosphorylated αCaMKII in the hippocampus and amygdala. We found that two hours after CFC training, young mice exhibited a higher level of phosphorylated and increased ratio of phosphorylated:total αCaMKII in hippocampal CA3 stratum radiatum. Furthermore, aged untrained mice showed a higher ratio of phosphorylated:total αCaMKII in the CA3 region of the hippocampus when compared to the young untrained group. No effect of training or aging were seen in the central, lateral and basolateral amygdala regions, for both phosphorylated and ratio of phosphorylated:total αCaMKII. These results show that aging impairs the training-induced upregulation of autophosphorylated (T286) αCaMKII in the CA3 stratum radiatum of the hippocampus. This indicates that distinct age-related mechanisms underlie CFC that may rely more heavily on NMDA receptor-dependent plasticity in young age

Synthesis and crystal structure of a new pyridinium bromide salt: 4-methyl-1-(3-phenoxypropyl)pyridinium bromide

In the cation of the title mol­ecular salt, C15H18NO+·Br−, the pyridinium and phenyl rings are inclined to one another by 11.80 (8)°. In the crystal, the Br− anion is linked to the cation by a C—H...Br hydrogen bond. The cations stack along the b-axis direction and are linked by further C—H...Br inter­actions, and offset π–π interactions [inter­centroid distances = 3.5733 (19) and 3.8457 (19) Å], forming slabs parallel to the ab plane. The effects of the C—H...X− inter­action on the NMR signals of the ortho- and meta-pyridinium protons in a series of related ionic liquids, viz. 4-methyl-1-(4-phen­oxy­but­yl)pyridin-1-ium salts, are reported and discussed

Instability and `Sausage-String' Appearance in Blood Vessels during High Blood Pressure

A new Rayleigh-type instability is proposed to explain the `sausage-string' pattern of alternating constrictions and dilatations formed in blood vessels under influence of a vasoconstricting agent. Our theory involves the nonlinear elasticity characteristics of the vessel wall, and provides predictions for the conditions under which the cylindrical form of a blood vessel becomes unstable.Comment: 4 pages, 4 figures submitted to Physical Review Letter

Out of sight but not out of harm’s way: human disturbance reduces reproductive success of a cavity-nesting seabird

While negative effects of human disturbance on animals living above the ground have been widely reported, few studies have considered effects on animals occupying cavities or burrows underground. It is generally assumed that, in the absence of direct visual contact, such species are less vulnerable to disturbance. Seabird colonies can support large populations of burrow- and cavity-nesting species and attract increasing numbers of tourists. We investigated the potential effects of recreational disturbance on the reproductive behaviour of the European storm petrel <i>Hydrobates pelagicus</i>, a nocturnally-active cavity-nesting seabird. Reproductive phenology and outcome of nests subject to high and low levels of visitor pressure were recorded in two consecutive years. Hatching success did not differ between disturbance levels, but overall nestling mortality was significantly higher in areas exposed to high visitor pressure. Although visitor numbers were consistent throughout the season, the magnitude and rate of a seasonal decline in productivity were significantly greater in nests subject to high disturbance. This study presents good evidence that, even when humans do not pose a direct mortality risk, animals may perceive them as a predation risk. This has implications for the conservation and management of a diverse range of burrow- and cavity-dwelling animals. Despite this reduction in individual fitness, overall colony productivity was reduced by ≤1.6% compared with that expected in the absence of visitors. While the colony-level consequences at the site in question may be considered minor, conservation managers must evaluate the trade-off between potential costs and benefits of public access on a site- and species-specific basis

Kinetics of charge transfer in DNA containing a mismatch

Charge transfer (CT) in DNA offers a unique approach for the detection of a single-base mismatch in a DNA molecule. While the single-base mismatch would significantly affect the CT in DNA, the kinetic basis for the drastic decrease in the CT efficiency through DNA containing mismatches still remains unclear. Recently, we determined the rate constants of the CT through the fully matched DNA, and we can now estimate the CT rate constant for a certain fully matched sequence. We assumed that further elucidating of the kinetics in mismatched sequences can lead to the discrimination of the DNA single-base mismatch based on the kinetics. In this study, we investigated the detailed kinetics of the CT through DNA containing mismatches and tried to discriminate a mismatch sequence based on the kinetics of the CT in DNA containing a mismatch

Patient-reported depression measures in cancer: a meta-review

The patient-reported depression measures that perform best in oncology settings have not yet been identified. We did a meta-review to integrate the findings of reviews of more than 50 depression measures used in adults with, or recovering from, any type of cancer. We searched Medline, PsycINFO, Embase, and grey literature from 1999 to 2014 to identify 19 reviews representing 372 primary studies. 11 reviews were rated as being of high quality (defined as meeting at least 20 criteria in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement). The Hospital Anxiety Depression Scale (HADS) was the most thoroughly evaluated measure, but was limited by cutpoint variability. The HADS had moderate screening utility indices and was least recommended in advanced cancer or palliative care. The Beck Depression Inventory was more generalisable across cancer types and disease stages, with good indices for screening and case finding. The Center for Epidemiologic Studies Depression Scale was the best-weighted measure in terms of responsiveness. This meta-review provides a comprehensive overview of the strengths and limitations of available depression measures. It can inform the choice of the best measure for specific settings and purposes

Middepth circulation of the eastern tropical South Pacific and its link to the oxygen minimum zone

There is an incomplete description of the mid-depth circulation and its link to the oxygen minimum zone (OMZ) in the eastern tropical South Pacific. Subsurface currents of the OMZ in the eastern tropical South Pacific are investigated with a focus at 400 m depth, close to the core of the OMZ, using several Acoustic Doppler Current Profiler sections recorded in January and February 2009. Five profiling floats with oxygen sensors were deployed along 85°50’W in February 2009 with a drift depth at 400 m. Their spreading paths are compared with the model flow field from a 1/10° Tropical Pacific model (TROPAC01) and the Simple Ocean Data Assimilation (SODA) model. Overall the mean currents in the eastern tropical South Pacific are weak so that eddy variability influences the flow and ultimately feed oxygen-poor water to the OMZ. The center of the OMZ is a stagnant area so that floats stay much longer in this region and can even reverse direction. In one case of one float deployed at 8°S returned to the same location after 15 month. On the northern side of the OMZ in the equatorial current system, floats move rapidly to the west. Most current bands reported for the near surface layer exist also in the depth range of the OMZ. A schematic circulation flow field for the OMZ core depth is derived which shows the northern part of the South Pacific subtropical gyre south of the OMZ and the complicated zonal equatorial flow field north of the OMZ

Disparities in psychosocial cancer care: a report from the International Federation of Psycho-oncology Societies.

BACKGROUND: The aim of the study was to understand the characteristics of the International Federation of Psycho-oncology Societies (FPOS) and possible disparities in providing psychosocial care in countries where psycho-oncology societies exist. METHOD: A survey was conducted among 29 leaders of 28 countries represented within the FPOS by using a questionnaire covering (i) characteristics of the society; (ii) characteristics of the national health care system; (iii) level of implementation of psycho-oncology; and (iv) main problems of psycho-oncology in the country. RESULTS: Twenty-six (90%) FPOS returned the questionnaires. One-third reported to have links with and support from their government, while almost all had links with other scientific societies. The FPOS varied in their composition of members' professions. Psychosocial care provision was covered by state-funded health services in a minority of countries. Disparities between countries arose from different causes and were problematic in some parts of the world (eg, Africa and SE Asia). Elsewhere (eg, Southern Europe and Eastern Europe), austerity policies were reportedly responsible for resource shortages with negative consequences on psychosocial cancer care. Half of FPOS rated themselves to be integrated into mainstream provision of care, although lack of funding was the most common complain. CONCLUSIONS: The development and implementation of psycho-oncology is fragmented and undeveloped, particularly in some parts of the world. More effort is needed at national level by strong coalitions with oncology societies, better national research initiatives, cancer plans, and patient advocacy, as well as by stronger partnership with international organizations (eg, World Health Organization and Union for International Cancer Control)