An investigation of the relationship between BOLD and perfusion signal changes during epileptic generalised spike wave activity

In pathological conditions interpretation of functional magnetic resonance imaging (fMRI) results can be difficult. This is due to a reliance on the assumed coupling between neuronal activity and changes in cerebral blood flow (CBF) and oxygenation. We wanted to investigate the coupling between blood oxygen level dependant contrast (BOLD) and CBF time courses in epilepsy patients with generalised spike wave activity (GSW) to better understand the underlying mechanisms behind the EEG-fMRI signal changes observed, especially in regions of negative BOLD response (NBR). Four patients with frequent GSW were scanned with simultaneous electroencephalographic (EEG)-fMRI with BOLD and arterial spin labeling (ASL) sequences. We examined the relationship between simultaneous CBF and BOLD measurements by looking at the correlation of the two signals in terms of percentage signal change on a voxel-by-voxel basis. This method is not reliant on coincident activation. BOLD and CBF were positively correlated in patients with epilepsy during background EEG activity and GSW. The subject average value of the ΔCBF/ΔBOLD slope lay between +19 and +36 and also showed spatial variation which could indicate areas with altered vascular response. There was not a significant difference between ΔCBF/ΔBOLD during GSW, suggesting that neurovascular coupling to BOLD signal is generally maintained between states and, in particular, within areas of NBR

Precision Ephemerides For Gravitational Wave Searches: II. Cyg X-2

Accreting neutron stars in low-mass X-ray binaries (LMXBs) are candidate high-frequency persistent gravitational wave sources. These may be detectable with next generation interferometers such as Advanced LIGO/VIRGO within this decade. However, the search sensitivity is expected to be limited principally by the uncertainty in the binary system parameters. We combine new optical spectroscopy of Cyg X-2 obtained with the Liverpool Telescope (LT) with available historical radial velocity data, which gives us improved orbital parameter uncertainties based on a 44-year baseline. We obtained an improvement of a factor of 2.6 in the orbital period precision and a factor of 2 in the epoch of inferior conjunction T_0. The updated orbital parameters imply a mass function of 0.65 +/- 0.01 M_sun, leading to a primary mass (M_1) of 1.67 +/- 0.22 M_sun (for i=62.5 +/- 4 deg). In addition, we estimate the likely orbital parameter precision through to the expected Advanced LIGO and VIRGO detector observing period and quantify the corresponding improvement in sensitivity via the required number of templates.Comment: 7 pages, 3 figures, accepted for publication by Ap

Adolescent Reproductive Knowledge, Attitudes, and Beliefs and Future Fatherhood.

PurposeWith a growing focus on the importance of men's reproductive health, including preconception health, the ways in which young men's knowledge, attitudes, and beliefs (KAB) predict their reproductive paths are understudied. To determine if reproductive KAB predicts fatherhood status, timing and residency (living with child or not).MethodsReproductive KAB and fatherhood outcomes were analyzed from the National Longitudinal Study of Adolescent Health, a 20-year, nationally representative study of individuals from adolescence into adulthood. Four measures of reproductive KAB were assessed during adolescence in waves I and II. A generalized linear latent and mixed model predicted future fatherhood status (nonfather, resident/nonresident father, adolescent father) and timing while controlling for other socio-demographic variables.ResultsOf the 10,253 men, 3,425 were fathers (686 nonresident/2,739 resident) by wave IV. Higher risky sexual behavior scores significantly increased the odds of becoming nonresident father (odds ratio [OR], 1.30; p < .0001), resident father (OR, 1.07; p = .007), and adolescent father (OR, 1.71; p < .0001); higher pregnancy attitudes scores significantly increased the odds of becoming a nonresident father (OR, 1.20; p < .0001) and resident father (OR, 1.11; p < .0001); higher birth control self-efficacy scores significantly decreased the odds of becoming a nonresident father (OR, .72; p < .0001) and adolescent father (OR, .56; p = .01).ConclusionsYoung men's KAB in adolescence predicts their future fatherhood and residency status. Strategies that address adolescent males' reproductive KAB are needed in the prevention of unintended reproductive consequences such as early and nonresident fatherhood

Longitudinal Study of Body Mass Index in Young Males and the Transition to Fatherhood.

Despite a growing understanding that the social determinants of health have an impact on body mass index (BMI), the role of fatherhood on young men's BMI is understudied. This longitudinal study examines BMI in young men over time as they transition from adolescence into fatherhood in a nationally representative sample. Data from all four waves of the National Longitudinal Study of Adolescent Health supported a 20-year longitudinal analysis of 10,253 men beginning in 1994. A "fatherhood-year" data set was created and changes in BMI were examined based on fatherhood status (nonfather, nonresident father, resident father), fatherhood years, and covariates. Though age is positively associated with BMI over all years for all men, comparing nonresident and resident fathers with nonfathers reveals different trajectories based on fatherhood status. Entrance into fatherhood is associated with an increase in BMI trajectory for both nonresident and resident fathers, while nonfathers exhibit a decrease over the same period. In this longitudinal, population-based study, fatherhood and residence status play a role in men's BMI. Designing obesity prevention interventions for young men that begin in adolescence and carry through young adulthood should target the distinctive needs of these populations, potentially improving their health outcomes

Defect healing and charge transfer mediated valley polarization in MoS2_2/MoSe2_2/MoS2_2 trilayer van der Waals heterostructures

Monolayer transition metal dichalcogenides (TMDC) grown by chemical vapor deposition (CVD) are plagued by a significantly lower optical quality compared to exfoliated TMDC. In this work we show that the optical quality of CVD-grown MoSe$_2$ is completely recovered if the material is sandwiched in MoS$_2$/MoSe$_2$/MoS$_2$ trilayer van der Waals heterostructures. We show by means of density-functional theory that this remarkable and unexpected result is due to defect healing: S atoms of the more reactive MoS$_2$ layers are donated to heal Se vacancy defects in the middle MoSe$_2$ layer. In addition, the trilayer structure exhibits a considerable charge-transfer mediated valley polarization of MoSe$_2$ without the need for resonant excitation. Our fabrication approach, relying solely on simple flake transfer technique, paves the way for the scalable production of large-area TMDC materials with excellent optical quality.Comment: Just accepted for publication in Nano Letters (http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.7b00904

Guidelines for Policy Modellers - 30 years on: New Tricks or Old Dogs?

Systems thinking and the use of modelling to assist in natural resources decision making started in the early 1960’s (Forrester, 1961). In the early 1970’s a multidisciplinary program was established in CSIRO’s Division of Land Resources Management to, among other issues, research and develop models to assist in the resolution of persistent and multi-faceted environmental issues. The authors of this paper were members of that group. We recently decided to look at what has been learned about these reasonably intractable problems over the more than 30 years period since. If it is true that the half life of modelling papers is around eight years and, apparently, decreasing (Haggett, 2005), then we can expect that the wheel has often been reinvented. So we describe issues as they were expressed up to the early 1980’s and compare and contrast them with concerns after the turn of the century in two contexts - the development of systems thinking in modelling and deciding when and how to model. Three general criticisms of systems analysis were evident then: (1) the models were highly mathematical and therefore opaque to the user, and it was hard even for ’experts’ to explain unexpected findings; (2) welfare, as expressed by economic or utilitarian criteria, was considered to be poorly represented in systems practice (systems thinking was being viewed here as rational, while it was slowly being recognized that apparently irrational behaviour is an important part of the social fabric and could not be ignored (Glazer, 1978)); (3) the systems approach relied on lists derived from planners, but in the absence of “systems thinking” guidelines they were only lists of what planners thought of doing, not comprehensive in any strong sense. These three major drawbacks still exist and in much the same form today. Development of systems thinking is now much more widespread. The applications gap does not appear to be filled, though there have been attempts to broaden the client base by participative model construction to reach a consensus of what is agreeable to most stakeholders. “Irrational behaviour” still threatens systems analysis and comes in several forms. There is lack of acceptance that utilitarian criteria should be used to drive the solution. And the consequences of implementing a model’s solution may lead to unforeseen consequences and behaviours by and to affected parties. Very few papers have been written in recent years on guidelines on when to model and when not to do so. There seems to be no connection with earlier publications. The field does not appear to have progressed. We perceive a world in which those who can, model, and those who can’t still feel little need to try. It is to be hoped that interest in the issues of when and why to model will not wane. It would be a shame, perhaps a source of conflict, if modelling remained yet another marker that separates a ‘them’ from an ‘us’. Some of us have now been much closer to decision-makers. Our observations include: (a) Timing is critical in decision-making. Sometimes there are a few hours for deliberation, for others decades. A modeller has to be close to help with the quick ones. Advice that comes too late will not be relevant. (b) Close contact with decision makers is essential, as is their training. (c) A contract from the client is a desirable/necessary precondition. (d) Trust, and lack of it, will always be important in accepting advice. (e) Committees, especially those charged with doing something and feel that they cannot progress without assistance, are good targets. But committees, like modelling contracts, can be solely methods of delaying decisions. (f) Modelling physical and biological systems is less contentious than using utility to guide advice

Template banks to search for compact binaries with spinning components in gravitational wave data

Gravitational waves from coalescing compact binaries are one of the most promising sources for detectors such as LIGO, Virgo and GEO600. If the components of the binary posess significant angular momentum (spin), as is likely to be the case if one component is a black hole, spin-induced precession of a binary's orbital plane causes modulation of the gravitational-wave amplitude and phase. If the templates used in a matched-filter search do not accurately model these effects then the sensitivity, and hence the detection rate, will be reduced. We investigate the ability of several search pipelines to detect gravitational waves from compact binaries with spin. We use the post-Newtonian approximation to model the inspiral phase of the signal and construct two new template banks using the phenomenological waveforms of Buonanno, Chen and Vallisneri. We compare the performance of these template banks to that of banks constructed using the stationary phase approximation to the non-spinning post-Newtonian inspiral waveform currently used by LIGO and Virgo in the search for compact binary coalescence. We find that, at the same false alarm rate, a search pipeline using phenomenological templates is no more effective than a pipeline which uses non-spinning templates. We recommend the continued use of the non-spinning stationary phase template bank until the false alarm rate associated with templates which include spin effects can be substantially reduced.Comment: 11 pages, 3 figure

A social mechanism facilitates ant colony emigrations overdifferent distances

Behavioural responses enable animals to react rapidly to fluctuating environments. In eusocial organisms, such changes are often enacted at the group level, but may be organised in a decentralised fashion by the actions of individuals. However, the contributions of different group members are rarely homogeneous, and there is evidence to suggest that certain ‘keystone’ individuals are important in shaping collective responses. Accordingly, investigations of the dynamics and structuring of behavioural changes at both the group and individual level are crucial for evaluating the relative influence of different individuals. Here, we examined the composition of tandem running behaviour during colony emigrations in the ant species Temnothorax albipennis. Tandem running is modulated in response to emigration distance, with more runs being conducted when a more distant nest site must be reached. We show that certain individuals are highly active in the tandem running process, attempting significantly more work in thetask. Contrary to expectations, however, such individuals are in fact no more successful at conducting tandem runs than their less active nest mates. Instead, it seems that when more tandem runs are required, colonies rely on greater recruitment of workers into the process. The implications of our study are that in some cases, even when apparently ‘key’ individuals exist within a group, their relative contribution to task performance may be far from decisive