Diffeomorphic demons using normalized mutual information, evaluation on multimodal brain MR images

The demons algorithm is a fast non-parametric non-rigid registration method. In recent years great efforts have been made to improve the approach; the state of the art version yields symmetric inverse-consistent largedeformation diffeomorphisms. However, only limited work has explored inter-modal similarity metrics, with no practical evaluation on multi-modality data. We present a diffeomorphic demons implementation using the analytical gradient of Normalised Mutual Information (NMI) in a conjugate gradient optimiser. We report the first qualitative and quantitative assessment of the demons for inter-modal registration. Experiments to spatially normalise real MR images, and to recover simulated deformation fields, demonstrate (i) similar accuracy from NMI-demons and classical demons when the latter may be used, and (ii) similar accuracy for NMI-demons on T1w-T1w and T1w-T2w registration, demonstrating its potential in multi-modal scenarios

Reconstructing the natural hydrology of the San Francisco Bay - Delta watershed

We evaluated the impact of landscape changes on the amount of delta outflow reaching San Francisco Bay. The natural landscape was reconstructed and water balances were used to estimate the long-term annual average delta outflow that would have occurred under natural landscape conditions if the climate from 1922 to 2009 were to repeat itself. These outflows are referred to as natural delta outflows and are the first published estimate of natural delta outflow. These natural delta outflows were then compared with current delta outflows for the same climate and existing landscape, including its re-engineered system of reservoirs, canals, aqueducts, and pumping plants. This analysis shows that the long-term, annual average delta outflow under current conditions is consistent with outflow under natural landscape conditions. The amount of water currently used by farms, cities, and others is about equal to the amount of water formerly used by native vegetation. Development of water resources in California’s Central Valley transferred water formerly used by native vegetation to new beneficial uses without substantially reducing the longterm annual average supply to the San Francisco Bay–Delta estuary. Based on this finding, it is unlikely that observed declines in native freshwater aquatic species are the result of annual average delta outflow reductions

Regulation of peripheral vascular tone in patients with heart failure:Contribution of angiotensin II

Objective—To determine directly the contribution of angiotensin II to basal and sympathetically stimulated peripheral arteriolar tone in patients with heart failure.
Design—Parallel group comparison.
Subjects—Nine patients with New York Heart Association grade II-IV chronic heart failure, and age and sex matched controls.
Interventions—Forearm plethysmography, lower body negative pressure, local intra-arterial administration of losartan, angiotensin II, and noradrenaline, and estimation of plasma hormone concentrations.
Main outcome measures—Forearm blood flow responses, plasma hormone concentrations.
Results—Baseline blood pressure, heart rate, and forearm blood flow did not differ between patients and controls. In comparison with the non-infused forearm, losartan did not affect basal forearm blood flow (95% confidence interval −5.5% to +7.3%) or sympathetically stimulated vasoconstriction in controls. However, the mean (SEM) blood flow in patients increased by 13(5)% and 26(7)% in response to 30 and 90 µg/min of losartan respectively (p < 0.001). Lower body negative pressure caused a reduction in forearm blood flow of 20(5)% in controls (p = 0.008) and 13(5)% (p = 0.08) in patients (p = 0.007, controls v patients). Blood flow at 90 µg/min of losartan correlated with plasma angiotensin II concentration (r = 0.77; p = 0.03). Responses to angiotensin II and noradrenaline did not differ between patients and controls.
Conclusions—Losartan causes acute local peripheral arteriolar vasodilatation in patients with heart failure but not in healthy control subjects. Endogenous angiotensin II directly contributes to basal peripheral arteriolar tone in patients with heart failure but does not augment sympathetically stimulated peripheral vascular tone.

 Keywords: angiotensin II;  heart failure;  peripheral vascular tone;  sympathetic nervous syste

Effects of electrical stimulation of dorsal raphe nucleus on neuronal response properties of barrel cortex layer IV neurons following long-term sensory deprivation

Abstract: Objective To evaluate the effect of electrical stimulation of dorsal raphe nucleus (DRN) on response properties of layer IV barrel cortex neurons following long-term sensory deprivation. Methods: Male Wistar rats were divided into sensory-deprived (SD) and control (unplucked) groups. In SD group, all vibrissae except the D2 vibrissa were plucked on postnatal day one, and kept plucked for a period of 60 d. After that, whisker regrowth was allowed for 8-10 d. The D2 principal whisker (PW) and the D1 adjacent whisker (AW) were either deflected singly or both deflected in a serial order that the AW was deflected 20 ms before PW deflection for assessing lateral inhibition, and neuronal responses were recorded from layer IV of the D2 barrel cortex. DRN was electrically stimulated at inter-stimulus intervals (ISIs) ranging from 0 to 800 ms before whisker deflection. Results: PW-evoked responses increased in the SD group with DRN electrical stimulation at ISIs of 50 ms and 100 ms, whereas AW-evoked responses increased at ISI of 800 ms in both groups. Whisker plucking before DRN stimulation could enhance the responsiveness of barrel cortex neurons to PW deflection and decrease the responsiveness to AW deflection. DRN electrical stimulation significantly reduced this difference only in PW-evoked responses between groups. Besides, no DRN stimulation-related changes in response latency were observed following PW or AW deflection in either group. Moreover, condition test (CT) ratio increased in SD rats, while DRN stimulation did not affect the CT ratio in either group. There was no obvious change in 5-HT2A receptor protein density in barrel cortex between SD and control groups. Conclusion: These results suggest that DRN electrical stimulation can modulate information processing in the SD barrel cortex

An experimental scale-model study of seismic response of an underground opening in jointed rock mass

This report describes an experimental investigation conducted by the Center for Nuclear Waste Regulatory Analyses (CNWRA) to (i) obtain a better understanding of the seismic response of an underground opening in a highly-fractured and jointed rock mass and (ii) generate a data set that can be used to evaluate the capabilities (analytical methods) to calculate such response. This report describes the design and implementation of simulated seismic experiments and results for a 1/15 scale model of a jointed rock mass with a circular tunnel in the middle. The discussion on the design of the scale model includes a description of the associated similitude theory, physical design rationale, model material development, preliminary analytical evaluation, instrumentation design and calibration, and model assembly and pretest procedures. The thrust of this discussion is intended to provide the information necessary to understand the experimental setup and to provide the background necessary to understand the experimental results. The discussion on the experimental procedures and results includes the seismic input test procedures, test runs, and measured excitation and response time histories. The closure of the tunnel due to various levels of seismic activity is presented. A threshold level of seismic input amplitude was required before significant rock mass motion occurred. The experiment, though designed as a two-dimensional representation of a rock mass, behaved in a somewhat three-dimensional manner, which will have an effect on subsequent analytical model comparison

Evaluation of a general practice based Hepatitis C virus screening intervention

In 2003 an estimated 37,500 of Scotland's population was chronically infected with HCV; 44% were undiagnosed former injecting drug users (IDU) - a priority group for arrival therapy. Aims to evaluate a hepatitis C virus (HCV) screening intervention. Outcomes measures among two similar general practice populations in an area of high HCV and drug use prevalence, one of which was exposed to an HCV screening intervention, were compared. Thirty to fifty four year old attendees of the intervention practice were opportunistically offered testing and counselling, where clinically appropriate, (November 2003 - April 2004). Outcomes: HCV test uptake, case detection, referral and treatment administration rates. Of 584 eligible attendees, 421 (72%) were offered and 117 (28%) accepted testing in the intervention practice; no testing was undertaken in the comparison practice. Prevalences of HCV antibody were 13% (15/117), 75% (3/4) and 91% (10/11) among all tested persons, current IDUs and former IDUs respectively. For 4/15 (27%) evidence of binge drinking following the receipt of their positive result, was available. Of the 11 referred to specialist care because they were HCV RNA positive, nine attended at least one appointment. Two received treatment: one had achieved a sustained viral response as of February 2008. While non targeted HCV screening in the general practice setting can detect infected former IDU, the low diagnostic yield among non IDUs limited the effectiveness of the intervention. A more targeted approach for identifying former IDUs is recommended. Additionally, the low uptake of treatment among chronically infected persons four years after diagnosis demonstrates the difficulties in clinically managing such individuals. Strategies, including support for those with a history of problem alcohol use, to improve treatment uptake are required

Symptomatic Sinus Node Disease: Natural History After Permanent Ventricular Pacing *

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75403/1/j.1540-8159.1979.tb03650.x.pd

Prevention of Decline in Cognition after Stroke Trial (PODCAST): a study protocol for a factorial randomised controlled trial of intensive versus guideline lowering of blood pressure and lipids

Background Stroke is a common cause of cognitive impairment and dementia. However, effective strategies for reducing the risk of post-stroke dementia remain undefined. Potential strategies include intensive lowering of blood pressure and/or lipids. Methods/Design Design: multi-centre prospective randomised open-label blinded-endpoint controlled partial-factorial phase IV trial in secondary and primary care. Participants: 100 participants from 30 UK Stroke Research Network sites who are post- ischemic stroke or intracerebral haemorrhage by three to seven months. Interventions - all patients (1:1): intensive versus guideline blood pressure lowering (target systolic < 125 mmHg versus < 140 mmHg). Interventions - ischemic stroke (1:1): intensive versus guideline lipid lowering (target low density lipoprotein-cholesterol (LDL-c) < 1.4 mmol/l versus < 3 mmol/l). Hypotheses: does ‘intensive’ blood pressure lowering therapy and/or ‘intensive’ lipid control reduce cognitive decline and dementia in people with ischemic stroke; and does ‘intensive’ blood pressure lowering therapy reduce cognitive decline and dementia in patients with hemorrhagic stroke. Primary outcome: Addenbrooke’s Cognitive Examination-Revised. Secondary outcomes: feasibility of recruitment and retention of participants, tolerability and safety of the interventions, achieving and maintaining the blood pressure and lipid targets, maintaining differences in systolic blood pressure (> 10 mmHg) and low density lipoprotein-cholesterol (> 1 mmol/l) between the treatment groups, and performing clinic and telephone follow-up of cognition measures. Randomisation: using stratification, minimization and simple randomization. Blinding: participants receive open-label management. Cognition is assessed both unblinded (in clinic) and blinded (by telephone) to treatment. Adjudication of events (dementia, vascular, serious adverse events) is blinded to management. Discussion The PODCAST trial is ongoing with 78 patients recruited to date from 22 sites. Outcomes of cognitive impairment and dementia are accruing. Trial registration ISRCTN8556238

Enhancing gravitational wave astronomy with galaxy catalogues

Joint gravitational wave (GW) and electromagnetic (EM) observations, as a key research direction in multi-messenger astronomy, will provide deep insight into the astrophysics of a vast range of astronomical phenomena. Uncertainties in the source sky location estimate from gravitational wave observations mean follow-up observatories must scan large portions of the sky for a potential companion signal. A general frame of joint GW-EM observations is presented by a multi-messenger observational triangle. Using a Bayesian approach to multi-messenger astronomy, we investigate the use of galaxy catalogue and host galaxy information to reduce the sky region over which follow-up observatories must scan, as well as study its use for improving the inclination angle estimates for coalescing binary compact objects. We demonstrate our method using a simulated neutron stars inspiral signal injected into simulated Advanced detectors noise and estimate the injected signal sky location and inclination angle using the Gravitational Wave Galaxy Catalogue. In this case study, the top three candidates in rank have $72\%$, $15\%$ and $8\%$ posterior probability of being the host galaxy, receptively. The standard deviation of cosine inclination angle (0.001) of the neutron stars binary using gravitational wave-galaxy information is much smaller than that (0.02) using only gravitational wave posterior samples.Comment: Proceedings of the Sant Cugat Forum on Astrophysics. 2014 Session on 'Gravitational Wave Astrophysics