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Vertigo and anxiety are frequent symptoms in both psychiatric and vertigo patients, especially in those with phobic postural vertigo (PPV). The aim of this study was the investigation of anxiety-associated functional responses in PPV patients compared to healthy controls. For that purpose cholecystokinin tetrapeptide (CCK-4), a valid model to experimentally induce anxiety symptoms, was used.
15 PPV patients and 15 matched healthy controls underwent challenges with CCK-4. During the paradigm, participants did not know the exact time point of the injection in order to separate the anticipatory and CCK-4 induced anxiety. The panic symptom scale score was assessed before and after the injection.
During anticipatory anxiety healthy controls showed functional responses mainly in fronto-temporal regions. Patients suffering from PPV showed pronounced BOLD responses in the (ventral) anterior cingulate cortex (ACC), dorsolateral prefrontal cortex, orbitofrontal cortex and precuneus. In healthy subjects, CCK-4 induced anxiety was accompanied by activations in the medial and inferior frontal cortex. In PPV, the CCK-4 injection led to increased activities particularly in the ACC, the cuneus, the cerebellum, the amygdala and fronto-temporal regions.
Given the fact of increased neuronal responses in emotion-related brain areas in patients with anxiety disorders these findings could provide evidence for common aspects of phobic postural vertigo and anxiety disorders.
Wolf-Rayet (WR) stars are stripped stellar cores that form through strong stellar wind or binary mass transfer. It is proposed that binary evolution plays a vital role in the formation of WR stars in low metallicity environments due to the metallicity dependance of stellar winds. However observations indicate a similar binary fraction of WR stars in the Small Magellanic Cloud (SMC) compared to the Milky Way. There are twelve WR stars in the SMC and five of them are members of binary systems. One of them (SMC AB8) harbors a WO type star. In this work we explore possible formation channels of this binary. We use the MESA code to compute large grids of binary evolution models, and then use least square fitting to compare our models with the observations. In order to reproduce the key properties of SMC AB8, we require efficient semiconvection to produce a sufficiently large convective core, as well as a longer He-burning lifetime. We also need a high mass loss rate during the WN stage to assist the removal of the outer envelope. In this way, we can reproduce the observed properties of AB8, except for the surface carbon to oxygen ratio, which requires further investigation.
We consider the steady two-dimensional thin-film version of a problem concerning a weightless non-isothermal free fluid film subject to thermocapillarity, proposed and analysed by Pukhnachev and co-workers. Specifically, we extend and correct the paper by Karabut and Pukhnachev (J. Appl. Mech. Tech. Phys. 49, 568–579, 2008), in which the problem is solved numerically, and in which it is claimed that there exists a unique solution for any value of a prescribed heat-flux parameter in the model. We present a closed-form (parametric) solution of the problem, and from this show that, on the contrary, solutions exist only when the heat-flux parameter is less than a critical value found numerically by Karabut and Pukhnachev, and that when this condition is satisfied there are in fact two solutions, one of which recovers that obtained numerically by Karabut and Pukhnachev, the other being new.
The B fields in OB stars (BOB) survey is an ESO large programme collecting spectropolarimetric observations for a large number of early-type stars in order to study the occurrence rate, properties, and ultimately the origin of magnetic fields in massive stars. As of July 2014, a total of 98 objects were observed over 20 nights with FORS2 and HARPSpol. Our preliminary results indicate that the fraction of magnetic OB stars with an organised, detectable field is low. This conclusion, now independently reached by two different surveys, has profound implications for any theoretical model attempting to explain the field formation in these objects. We discuss in this contribution some important issues addressed by our observations (e.g., the lower bound of the field strength) and the discovery of some remarkable objects.
We present a mechanism for generating cosmological magnetic fields during the Epoch of Reionization, based on the photoionization of intergalactic hydrogen. A general formula is presented, together with an example numerical application which yields magnetic field strengths between 10−23 to 10−19 G on intersource scales. This mechanism, which operates all along Reionization around any ionizing source, participates to the premagnetization of the whole intergalactic medium. Also, the spatial configuration of these fields may help discriminate them from those produced by other mechanisms in future observations.
In 2008, Granett et al. claimed a direct detection of the integrated Sachs-Wolfe (iSW) effect, through the stacking of CMB patches at the positions of identified superstructures. Additionally, the high amplitude of their measured signal was reported to be at odds with predictions from the standard model of cosmology. However, a closer inspection of these results prompts multiple questions, more specifically about the amplitude and significance of the expected signal. We propose here an original theoretical prediction of the iSW effect produced by such superstructures. We use simulations based on GR and the LTB metric to reproduce cosmic structures and predict their exact theoretical iSW effect on the CMB. The amplitudes predicted with this method are consistent with the signal measured when properly accounting the contribution of the non-negligible (and fortuitous) primordial CMB fluctuations to the total signal. It also highlights the tricky nature of stacking measurements and their interpretation.
We assess the runoff and surface mass balance (SMB) of the Greenland ice sheet in the Nuuk region (southwest) using output of two regional climate models (RCMs) evaluated by observations. The region encompasses six glaciers that drain into Godthåbsfjord. RCM data (1960–2012) are resampled to a high spatial resolution to include the narrow (relative to the native grid spacing) glacier trunks in the ice mask. Comparing RCM gridded results with automatic weather station (AWS) point measurements reveals that locally models can underestimate ablation and overestimate accumulation by up to tens of per cent. However, comparison with lake discharge indicates that modelled regional runoff totals are more accurate. Model results show that melt and runoff in the Nuuk region have doubled over the past two decades. Regional SMB attained negative values in recent high-melt years. Taking into account frontal ablation of the marine-terminating glaciers, the region lost 10–20 km3 w.e. a–1 in 2010–12. If 2010 melting prevails during the remainder of this century, a low-end estimate of sea-level rise of 5 mm is expected by 2100 from this relatively small section (2.6%) of the ice sheet alone.
The Dominion Radio Astrophysical Observatory (DRAO) is carrying out a survey as part of an international collaboration to image the northe, at a common resolution, in emission from all major constituents of the interstellar medium; the neutral atomic gas, the molecular gas, the ionised gas, dust and relativistic plasma. For many of these constituents the angular resolution of the images (1 arcmin) will be more than a factor of 10 better than any previous studies. The aim is to produce a publicly-available database of high resolution, high-dynamic range images of the Galaxy for multi-phase studies of the physical states and processes in the interstellar medium. We will sketch the main scientific motivations as well as describe some preliminary results from the Canadian Galactic Plane Survey/Releve Canadien du Plan Galactique (CGPS/RCPG).
The Herschel HIFI Key Program, Galactic Observations of
Terahertz C+ (GOT C+) is a survey of
[CII] 1.9 THz emission throughout the Galaxy. Comparison of the first results of this
survey with HI and CO isotopomer emission reveals excess [CII] emission beyond that
expected from HI and CO layers alone, and is best explained as coming from a hidden layer
of H2 gas, the so-called ISM “dark gas”.
The Tarantula Survey is an ESO Large Programme which has obtained multi-epoch spectroscopy of over 1,000 massive stars in the 30 Doradus region of the Large Magellanic Cloud. The assembled consortium will exploit these data to address a range of fundamental questions in both stellar and cluster evolution.
We highlight the role of the light elements (Li, Be, B) in the evolution of massive single and binary stars, which is largely restricted to a diagnostic value, and foremost so for the element boron. However, we show that the boron surface abundance in massive early type stars contains key information about their foregoing evolution which is not obtainable otherwise. In particular, it allows to constrain internal mixing processes and potential previous mass transfer event for binary stars (even if the companion has disappeared). It may also help solving the mystery of the slowly rotating nitrogen-rich massive main sequence stars.
Excessive weight loss due to protein calorie malnutrition (PCM) is a significant problem in Nigerian children. This syndrome may be difficult to differentiate from the wasting disease caused by human immunodeficiency virus type 1 (HIV-1) infection. We studied 70 children admitted to the Baptist Medical Center in Ogbomosho, Nigeria in 1990 with PCM for prevalence of antibodies to HIV-1 and HIV-2. The cohort was from low-risk mothers and had a median age of 25 months (range, 4 months–9 years) with a weight deficit of at least 20% of the theoretical weight for age. Two sera were positive for anti-HIV-1 by both ELISA and Western blot (WB). A high prevalence of samples negative for HIV-1 antibody by ELISA were repeatedly reactive (11%, 8/70) or indeterminate (46%. 32/70) by WB. None of the sera was positive for antibody to HIV-2. There was no correlation of ELISA positivity or extent of WB banding with successful recovery from malnutrition. These results indicate a relatively low but significant prevalence of HIV-1 infection in Nigerian children with PCM. The high prevalence of indeterminate reactions in WB assays for HIV-1 suggests that other procedures may be necessary for confirmatory diagnosis of HIY-1 infection in this African population.
Abundance anomalies observed in globular cluster stars indicate pollution with material processed by hydrogen burning. Two main sources have been suggested: asymptotic giant branch (AGB) stars and massive stars rotating near the break-up limit (spin stars). We discuss the idea that massive binaries may provide an interesting alternative source of processed material. We discuss observational evidence for mass shedding from interacting binaries. In contrast to the fast, radiatively driven winds of massive stars, this material is typically ejected with low velocity. We expect that it remains inside the potential well of a globular cluster and becomes available for the formation or pollution of a second generation of stars. We estimate that the amount of processed low-velocity material that can be ejected by massive binaries is larger than the contribution of the two previously suggested sources combined.
The Tarantula Survey is an ambitious ESO Large Programme that has obtained multi-epoch spectroscopy of over 1000 massive stars in the 30 Doradus region in the Large Magellanic Cloud. Here, we introduce the scientific motivations of the survey and give an overview of the observational sample. Ultimately, quantitative analysis of every star, paying particular attention to the effects of rotational mixing and binarity, will be used to address fundamental questions in both stellar and cluster evolution.
With growth in retail sales estimated by industry at 15–25% yr−1, organic food represents the only significant growth sector in Canada's food system. This reality, in combination with mounting evidence that substantial environmental and economic benefits can arise from organic farming adoption, suggests that organic sector development should be a priority for governments. However, organic food remains a marginal component of Canadian agricultural and trade policy. This study was designed to examine the opportunities and costs to the province of Ontario of strategic investment in the expansion of the organic sector. Drawing on existing literature and Ontario land use and production data, the study used an iterative process to identify how the province could reach a target of 10% of Ontario's cropped acres in organic production within 15 years, from the current level of about 1%. We concluded that after 15 years 5343 organic farmers would be producing organically in all major commodities, including 4254 converting farmers entering the organic sector and 600 new entrants to farming. The 489 organic farms reported in 2004 would be included in this total of 5343 because we assume that they all make modest additions over this time period to their existing operations. Organic production would occur on about 367,000 ha of land, and some 1.4 million animals would be reared organically. After 15 years, these farmers would reduce fertilizer applications by about 43 million kg (saving $18.4 million yr−1), pesticide applications by about 296,000 kg active ingredient (saving $9.1 million yr−1), and 7079 kg of growth-promoting antibiotics/medications consumed in animal feed. This 30-point program would require new investments by the provincial government of about $51 million over 15 years. Phase I (first 5 years) costs would total $7.1 million and Phase II (following 10 years) costs $43.9 million. Net program costs would be significantly lower since farmers would have directly saved on inputs and received premium organic prices for most of their goods sold, thereby reducing government costs related to supporting farm finances. Additionally, this program would contribute significantly to reducing the externalized costs of current approaches to agriculture, conservatively estimated at $145 million annually or $2.18 billion over the 15-year life of the program. Not all those costs would be saved within 15 years, but this exceedingly modest investment in organic production, representing only 2.3% of these externalized costs, would generate savings in externalized costs far beyond this one-time investment. Implementation of this plan would allow domestic producers to capture 51% of Ontario's organic consumption, up from the currently low-range estimate of 15%. Organic foods would represent 1.9% of the total food retail market after 5 years and 5.3% of the total market after 15 years.
Cell encapsulation has been broadly investigated as a technology to provide immunoprotection for transplanted endocrine cells. Here we develop a new fabrication method that allows for rapid, homogenous microencapsulation of insulin-secreting cells with varying microscale geometries and asymmetrically modified surfaces. Micromolding systems were developed using polypropylene mesh, and the mesh material/surface properties associated with efficient encapsulation were identified. Cells encapsulated using these methods maintain desirable viability and preserve their ability to proliferate and secrete insulin in a glucose-responsive manner. This new cell encapsulation approach enables a practical route to an inexpensive and convenient process for the generation of cell-laden microcapsules without requiring any specialized equipment or microfabrication process.
Rotational mixing a very important but uncertain process in the evolution of massive stars. We propose to use close binaries to test its efficiency. Based on rotating single stellar models we predict nitrogen surface enhancements for tidally locked binaries. Furthermore we demonstrate the possibility of a new evolutionary scenario for very massive (M > 40M⊙) close (P < 3 days) binaries: Case M, in which mixing is so efficient that the stars evolve quasi-chemically homogeneously, stay compact and avoid any Roche-lobe overflow, leading to very close (double) WR binaries.
The dynamic behaviour of magneto-mechanical sensors and actuators can be completely described by Maxwell's and Navier-Lamé's partial differential equations (PDEs) with appropriate coupling terms reflecting the interactions of these fields and with the corresponding initial, boundary and interface conditions. Neglecting the displacement currents, which can be done for the classes of problems considered in this paper, and introducing the vector potential for the magnetic field, we arrive at a system of degenerate parabolic PDEs for the vector potential coupled with the hyperbolic PDEs for the displacements.Usually the computational domain, the finite element discretization, the time integration, and the solver are different for the magnetic and mechanical parts. For instance, the vector potential is approximated by edge elements whereas the finite element discretization of the displacements is based on nodal elements on different meshes. The most time consuming modules in the solution procedure are the solvers for both, the magnetical and the mechanical finite element equations arising at each step of the time integration procedure. We use geometrical multigrid solvers which are different for both parts. These multigrid solvers enable us to solve quite efficiently not only academic test problems, but also transient 3D technical magneto-mechanical systems of high complexity such as solenoid valves and electro-magnetic-acoustic transducers. The results of the computer simulation are in very good agreement with the experimental data.
The integration of optical interconnects in printed circuit boards (PCB) is a rapidly growing field worldwide due to a continuously increasing need for high-speed data transfer. There are any concepts discussed, among which are the integration of optical fibers or the generation of waveguides by UV lithography, embossing, or direct laser writing. The devices presented so far require many different materials and process steps, but particularly also highly-sophisticated assembly steps in order to couple the optoelectronic elements to the generated waveguides. In order to overcome these restrictions, an innovative approach is presented which allows the embedding of optoelectronic components and the generation of optical waveguides in only one optical material. This material is an inorganic-organic hybrid polymer, in which the waveguides are processed by two-photon absorption (TPA) processes, initiated by ultra-short laser pulses. In particular, due to this integration and the possibility of in situ positioning the optical waveguides with respect to the optoelectronic components by the TPA process, no complex packaging or assembly is necessary. Thus, the number of necessary processing steps is significantly reduced, which also contributes to the saving of resources such as energy or solvents. The material properties and the underlying processes will be discussed with respect to optical data transfer in PCBs.
The goal of recent shear-transformation-zone (STZ) theories has been to construct a phenomenological description of amorphous plasticity that is based on physical principles and molecular models, and yet is simple enough to be useful in predicting the performance of real materials. In reporting progress toward this goal, I focus on the dynamic role played by the effective disorder temperature (a generalization of the free-volume) in controlling relaxation rates and predicting shear-banding instabilities.