597,149 research outputs found
Association Between Vestibular Migraine and Migraine Headache: Yet to Explore.
ObjectivesTo evaluate if patients with a diagnosis of vestibular migraine (VM) by the International Classification of Headache Disorders (ICHD) criteria have meaningful differences in symptomatology and disease characteristics when compared to patients with concurrent vestibular symptoms and migraine that do not meet ICHD criteria.MethodsPatients who presented for the evaluation of vertigo were provided a detailed questionnaire about dizziness and migraine symptoms. Patients were assigned to either VM cohort (met ICHD criteria for VM) or migraine headache (MH) cohort (met ICHD criteria for migraine with or without aura but not VM). Disease characteristics, symptomatology, quality of life, and perceived stress score were compared between the cohorts.ResultsThe VM cohort demonstrated a shorter duration of vertigo episodes, 11â±â22âhours versus 84â±â146âhours in the MH cohort. In the VM cohort, 81% reported experiencing migraine headaches during episodes of vertigo, versus 61% in the MH cohort. All patients in the VM cohort reported a previous diagnosis of migraine headache, whereas 9% of the MH cohort had not been previously diagnosed by another physician. There was no difference in quality of life or perceived stress scores between the cohorts.ConclusionsA large proportion of vertigo patients with migrainous features do not meet the ICHD criteria for VM. The differences between cohorts represent selection bias rather than meaningful features unique to the cohorts. As such, VM and MH with vestibular symptoms may exist on a spectrum of the same disease process and may warrant the same treatment protocols
Some remarks on one-dimensional force-free Vlasov-Maxwell equilibria
The conditions for the existence of force-free non-relativistic
translationally invariant one-dimensional (1D) Vlasov-Maxwell (VM) equilibria
are investigated using general properties of the 1D VM equilibrium problem. As
has been shown before, the 1D VM equilibrium equations are equivalent to the
motion of a pseudo-particle in a conservative pseudo-potential, with the
pseudo-potential being proportional to one of the diagonal components of the
plasma pressure tensor. The basic equations are here derived in a different way
to previous work. Based on this theoretical framework, a necessary condition on
the pseudo-potential (plasma pressure) to allow for force-free 1D VM equilibria
is formulated. It is shown that linear force-free 1D VM solutions, which so far
are the only force-free 1D VM solutions known, correspond to the case where the
pseudo-potential is an attractive central potential. A general class of
distribution functions leading to central pseudo-potentials is discussed.Comment: Physics of Plasmas, accepte
Value management in practice: an interview survey
The results of an interview survey are provided involving 17 professionals working in the property and construction industry, mainly from Australia, concerning their actual experiences and observations of the Value Management (VM) process and outcomes. The main finding is that VM is popular among those with experience in its use, with an average 33% acceptance of the VM workshop - its use having extended even into the area of consultant selection. Much of the intervieweesâ experiences are related qualitatively in terms of VM contribution to the identification and management of the risks involved in project delivery
Dominance attributions following damage to the ventromedial prefrontal cortex
Damage to the human ventromedial prefrontal cortex (VM) can result in dramatic and maladaptive changes in social behavior despite preservation of most other cognitive abilities. One important aspect of social cognition is the ability to detect social dominance, a process of attributing from particular social signals another person's relative standing in the social world. To test the role of the VM in making attributions of social dominance, we designed two experiments: one requiring dominance judgments from static pictures of faces, the second requiring dominance judgments from film clips. We tested three demographically matched groups of subjects: subjects with focal lesions in the VM (n=15), brain-damaged comparison subjects with lesions excluding the VM (n=11), and a reference group of normal individuals with no history of neurological disease (n=32). Contrary to our expectation, we found that subjects with VM lesions gave dominance judgments on both tasks that did not differ significantly from those given by the other groups. Despite their grossly normal performance, however, subjects with VM lesions showed more subtle impairments specifically when judging static faces: They were less discriminative in their dominance judgments, and did not appear to make normal use of gender and age of the faces in forming their judgments. The findings suggest that, in the laboratory tasks we used, damage to the VM does not necessarily impair judgments of social dominance, although it appears to result in alterations in strategy that might translate into behavioral impairments in real life
Diffusion bonding of IN 718 to VM 350 grade maraging steel
Diffusion bonding studies have been conducted on IN 718, VM 350 and the dissimilar alloy couple, IN 718 to maraging steel. The experimental processing parameters critical to obtaining consistently good diffusion bonds between IN 718 and VM 350 were determined. Interrelationships between temperature, pressure and surface preparation were explored for short bending intervals under vacuum conditions. Successful joining was achieved for a range of bonding cycle temperatures, pressures and surface preparations. The strength of the weaker parent material was used as a criterion for a successful tensile test of the heat treated bond. Studies of VM-350/VM-350 couples in the as-bonded condition showed a greater yielding and failure outside the bond region
A Bag-of-Tasks Scheduler Tolerant to Temporal Failures in Clouds
Cloud platforms have emerged as a prominent environment to execute high
performance computing (HPC) applications providing on-demand resources as well
as scalability. They usually offer different classes of Virtual Machines (VMs)
which ensure different guarantees in terms of availability and volatility,
provisioning the same resource through multiple pricing models. For instance,
in Amazon EC2 cloud, the user pays per hour for on-demand VMs while spot VMs
are unused instances available for lower price. Despite the monetary
advantages, a spot VM can be terminated, stopped, or hibernated by EC2 at any
moment.
Using both hibernation-prone spot VMs (for cost sake) and on-demand VMs, we
propose in this paper a static scheduling for HPC applications which are
composed by independent tasks (bag-of-task) with deadline constraints. However,
if a spot VM hibernates and it does not resume within a time which guarantees
the application's deadline, a temporal failure takes place. Our scheduling,
thus, aims at minimizing monetary costs of bag-of-tasks applications in EC2
cloud, respecting its deadline and avoiding temporal failures. To this end, our
algorithm statically creates two scheduling maps: (i) the first one contains,
for each task, its starting time and on which VM (i.e., an available spot or
on-demand VM with the current lowest price) the task should execute; (ii) the
second one contains, for each task allocated on a VM spot in the first map, its
starting time and on which on-demand VM it should be executed to meet the
application deadline in order to avoid temporal failures. The latter will be
used whenever the hibernation period of a spot VM exceeds a time limit.
Performance results from simulation with task execution traces, configuration
of Amazon EC2 VM classes, and VMs market history confirms the effectiveness of
our scheduling and that it tolerates temporal failures
Adding the agentic capacities of visual materials to visual research ethics
The focus of visual research ethics has largely been on the ethical effects of visual research on participants. There is increasing identification of how researchers are ethically affected by visual research. However, there has been no sustained examination into how visual materials themselves have ethical consequences in visual research. In this paper we argue visual research presents with particular ethical challenges because of the agentic capacities of the visual materials themselves. The paper draws on a research project where participants generated two different kinds of visual materials: timeline charts and photos. We show how timeline charts and photos have contrasting imaginative, bodily, memory and synaesthetic capacities. The agentic capacities of the visual materials act in specific ways to co-create a network of relations across the research encounters. This network of relations has the capacity to act in particular ethical ways with serious consequences not just for research participants, but also for researchers. We propose the action of visual materials themselves needs to be added to ethical discussion about visual research. Drawing on the concept of ethical sustainability, we advocate for extending situated ethics and researcher reflexivity to include consideration of the agentic capacities of visual materials themselves
The Murphy-Good plot: a better method of analysing field emission data
Measured field electron emission (FE) current-voltage Im(Vm) data are
traditionally analysed via Fowler-Nordheim (FN) plots, as ln{Im/(Vm)**2} vs
1/Vm. These have been used since 1929, because in 1928 FN predicted they would
be linear. In the 1950s, a mistake in FN's thinking was found. Corrected theory
by Murphy and Good (MG) made theoretical FN plots slightly curved. This causes
difficulties when attempting to extract precise values of emission
characterization parameters from straight lines fitted to experimental FN
plots. Improved mathematical understanding, from 2006 onwards, has now enabled
a new FE data-plot form, the "Murphy-Good plot". This plots
ln{Im/(Vm)**(2-({\eta}/6)} vs 1/Vm, where {\eta} depends only on local work
function. Modern ("21st century") MG theory predicts that a theoretical MG plot
should be "almost exactly" straight. This makes precise extraction of
well-defined characterization parameters from ideal I_m(V_m) data much easier.
This article gives the theory needed to extract characterization parameters
from MG plots, setting it within the framework of wider difficulties in
interpreting FE Im(Vm) data (among them, use of the "planar emission
approximation"). Careful use of MG plots could also help remedy other problems
in FE technological literature. It is argued MG plots should now supersede FN
plots.Comment: Intended articl
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