Spontaneous charged lipid transfer between lipid vesicles

An assay to study the spontaneous charged lipid transfer between lipid vesicles is described. A donor/acceptor vesicle system is employed, where neutrally charged acceptor vesicles are fluorescently labelled with the electrostatic membrane probe Fluoresceinphosphatidylethanolamine (FPE). Upon addition of charged donor vesicles, transfer of negatively charged lipid occurs, resulting in a fluorescently detectable change in the membrane potential of the acceptor vesicles. Using this approach we have studied the transfer properties of a range of lipids, varying both the headgroup and the chain length. At the low vesicle concentrations chosen, the transfer follows a first-order process where lipid monomers are transferred presumably through the aqueous solution phase from donor to acceptor vesicle. The rate of transfer decreases with increasing chain length which is consistent with energy models previously reported for lipid monomer vesicle interactions. Our assay improves on existing methods allowing the study of a range of unmodified lipids, continuous monitoring of transfer and simplified experimental procedures

Extragalactic Radio Continuum Surveys and the Transformation of Radio Astronomy

Next-generation radio surveys are about to transform radio astronomy by discovering and studying tens of millions of previously unknown radio sources. These surveys will provide new insights to understand the evolution of galaxies, measuring the evolution of the cosmic star formation rate, and rivalling traditional techniques in the measurement of fundamental cosmological parameters. By observing a new volume of observational parameter space, they are also likely to discover unexpected new phenomena. This review traces the evolution of extragalactic radio continuum surveys from the earliest days of radio astronomy to the present, and identifies the challenges that must be overcome to achieve this transformational change.Comment: To be published in Nature Astronomy 18 Sept 201

Symptomatic relief precedes improvement of myocardial blood flow in patients under spinal cord stimulation

BACKGROUND: Spinal cord electrical stimulation (SCS) has shown to be a treatment option for patients suffering from angina pectoris CCS III-IV although being on optimal medication and not suitable for conventional treatment strategies, e.g. CABG or PTCA. Although many studies demonstrated a clear symptomatic relief under SCS therapy, there are only a few short-term studies that investigated alterations in cardiac ischemia. Therefore doubts remain whether SCS has a direct effect on myocardial perfusion. METHODS: A prospective study to investigate the short- and long-term effect of spinal cord stimulation (SCS) on myocardial ischemia in patients with refractory angina pectoris and coronary multivessel disease was designed. Myocardial ischemia was measured by MIBI-SPECT scintigraphy 3 months and 12 months after the beginning of neurostimulation. To further examine the relation between cardiac perfusion and functional status of the patients we measured exercise capacity (bicycle ergometry and 6-minute walk test), symptoms and quality of life (Seattle Angina Questionnaire [SAQ]), as well. RESULTS: 31 patients (65 ± 11 SEM years; 25 male, 6 female) were included into the study. The average consumption of short acting nitrates (SAN) decreased rapidly from 12 ± 1.6 times to 3 ± 1 times per week. The walking distance and the maximum workload increased from 143 ± 22 to 225 ± 24 meters and 68 ± 7 to 96 ± 12 watt after 3 months. Quality of life increased (SAQ) significantly after 3 month compared to baseline, as well. No further improvement was observed after one year of treament. Despite the symptomatic relief and the improvement in maximal workload computer based analysis (Emory Cardiac Toolbox) of the MIBI-SPECT studies after 3 months of treatment did not show significant alterations of myocardial ischemia compared to baseline (16 patients idem, 7 with increase and 6 with decrease of ischemia, 2 patients dropped out during initial test phase). Interestingly, in the long-term follow up after one year 16 patients (of 27 who completed the one year follow up) showed a clear decrease of myocardial ischemia and only one patient still had an increase of ischemia compared to baseline. CONCLUSION: Thus, spinal cord stimulation not only relieves symptoms, but reduces myocardial ischemia as well. However, since improvement in symptoms and exercise capacity starts much earlier, decreased myocardial ischemia might not be a direct effect of neurostimulation but rather be due to a better coronary collateralisation because of an enhanced physical activity of the patients

Robust Poisson Surface Reconstruction

Abstract. We propose a method to reconstruct surfaces from oriented point clouds with non-uniform sampling and noise by formulating the problem as a convex minimization that reconstructs the indicator func-tion of the surface’s interior. Compared to previous models, our recon-struction is robust to noise and outliers because it substitutes the least-squares fidelity term by a robust Huber penalty; this allows to recover sharp corners and avoids the shrinking bias of least squares. We choose an implicit parametrization to reconstruct surfaces of unknown topology and close large gaps in the point cloud. For an efficient representation, we approximate the implicit function by a hierarchy of locally supported basis elements adapted to the geometry of the surface. Unlike ad-hoc bases over an octree, our hierarchical B-splines from isogeometric analysis locally adapt the mesh and degree of the splines during reconstruction. The hi-erarchical structure of the basis speeds-up the minimization and efficiently represents clustered data. We also advocate for convex optimization, in-stead isogeometric finite-element techniques, to efficiently solve the min-imization and allow for non-differentiable functionals. Experiments show state-of-the-art performance within a more flexible framework.

Cohort study of Western Australia computed tomography utilisation patterns and their policy implications

Background: Computed tomography (CT) scanning is a relatively high radiation dose diagnostic imaging modality with increasing concerns about radiation exposure burden at the population level in scientific literature. This study examined the epidemiology of adult CT utilisation in Western Australia (WA) in both the public hospital and private practice settings, and the policy implications. Methods: Retrospective cohort design using aggregate adult CT data from WA public hospitals and Medical Benefits Schedule (MBS) (mid-2006 to mid-2012). CT scanning trends by sex, age, provider setting and anatomical areas were explored using crude CT scanning rates, age-standardised CT scanning rates and Poisson regression modelling. Results: From mid-2006 to mid-2012 the WA adult CT scanning rate was 129 scans per 1,000 person-years (PY). Females were consistently scanned at a higher rate than males. Patients over 65 years presented the highest scanning rates (over 300 scans per 1,000 PY). Private practice accounted for 73% of adult CT scans, comprising the majority in every anatomical area. In the private setting females predominately held higher age-standardised CT scanning rates than males. This trend reversed in the public hospital setting. Patients over 85 years in the public hospital setting were the most likely age group CT scanned in nine of ten anatomical areas. Patients in the private practice setting aged 85+ years were relatively less prominent across every anatomical area, and the least likely age group scanned in facial bones and multiple areas CT scans.Conclusion: In comparison to the public hospital setting, the MBS subsidised private sector tended to service females and relatively younger patients with a more diverse range of anatomical areas, constituting the majority of CT scans performed in WA. Patient risk and subsequent burden is greater for females, lower ages and some anatomical areas. In the context of a national health system, Australia has various avenues to monitor radiation exposure levels, improve physician training and modify funding mechanisms to ensure individual and population medical radiation exposure is as low as reasonably achievable

Search for Nucleon Decay with Final States l+ eta, nubar eta, and nubar pi+,0 Using Soudan 2

We have searched for nucleon decay into five two-body final states using a 4.4 kiloton-year fiducial exposure of the Soudan 2 iron tracking calorimeter. For proton decay into the fully visible final states mu+ eta and e+ eta, we observe zero and one event, respectively, that satisfy our search criteria for nucleon decay. The lifetime lower limits (tau/B) thus implied are 89 x 10^30 years and 81 x 10^30 years at 90% confidence level. For neutron decay into nubar eta, we obtain the lifetime lower limit 71 x 10^30 years. Limits are also reported for neutron decay into nubar pi0, and for proton decay into nubar pi+.Comment: 24 pages, 9 figures, 3 table

On the Polynomial Measurement Error Model

This paper discusses point estimation of the coefficients of polynomial measurement error (errors-in-variables) models. This includes functional and structural models. The connection between these models and total least squares (TLS) is also examined. A compendium of existing as well as new results is presented

DIRECT trial. Diverticulitis recurrences or continuing symptoms: Operative versus conservative Treatment. A MULTICENTER RANDOMISED CLINICAL TRIAL

Background: Persisting abdominal complaints are common after an episode of diverticulitis treated conservatively. Furthermore, some patients develop frequent recurrences. These two groups of patients suffer greatly from their disease, as shown by impaired health related quality of life and increased costs due to multiple specialist consultations, pain medication and productivity losses. Both conservative and operative management of patients with persisting abdominal complaints after an episode of diverticulitis and/or frequently recurring diverticulitis are applied. However, direct comparison by a randomised controlled trial is necessary to determine which is superior in relieving symptoms, optimising health related quality of life, minimising costs and preventing diverticulitis recurrences against acceptable morbidity and mortality associated with surgery or the occurrence of a complicated recurrence after conservative management. We, therefore, constructed a randomised clinical trial comparing these two treatment strategies. Methods/design: The DIRECT trial is a multicenter randomised clinical trial. Patients (18-75 years) presenting themselves with persisting abdominal complaints after an episode of diverticulitis and/or three or more recurrences within 2 years will be included and randomised. Patients randomised for conservative treatment are treated according to the current daily practice (antibiotics, analgetics and/or expectant management). Patients randomised for elective resection will undergo an elective resection of the affected colon segment. Preferably, a laparoscopic approach is used. The primary outcome is health related quality of life measured by the Gastro-intestinal Quality of Life Index, Short-Form 36, EQ-5D and a visual analogue scale for pain quantification. Secondary endpoints are morbidity, mortality and total costs. The total follow-u