170 research outputs found
Relativistic electrons from sparks in the laboratory
Discharge experiments were carried out at the Eindhoven University of
Technology in 2013. The experimental setup was designed to search for electrons
produced in meter-scale sparks using a 1 MV Marx generator. Negative voltage
was applied to the high voltage (HV) electrode. Five thin (1 mm) plastic
detectors (5 each) were distributed in various configurations close
to the spark gap. Earlier studies have shown (for HV negative) that X-rays are
produced when a cloud of streamers is developed 30-60 cm from the negative
electrode. This indicates that the electrons producing the X-rays are also
accelerated at this location, that could be in the strong electric field from
counterstreamers of opposite polarity. Comparing our measurements with modeling
results, we find that 300 keV electrons produced about 30-60 cm from the
negative electrode are the most likely source of our measurements. A
statistical analysis of expected detection of photon bursts by these fiber
detectors indicates that only 20%-45% of the detected bursts could be from soft
(10 keV) photons, which further supports that the majority of detected
bursts are produced by relativistic electrons
Gravitational Ionization: A Chaotic Net in the Kepler System
The long term nonlinear dynamics of a Keplerian binary system under the
combined influences of gravitational radiation damping and external tidal
perturbations is analyzed. Gravitational radiation reaction leads the binary
system towards eventual collapse, while the external periodic perturbations
could lead to the ionization of the system via Arnold diffusion. When these two
opposing tendencies nearly balance each other, interesting chaotic behavior
occurs that is briefly studied in this paper. It is possible to show that
periodic orbits can exist in this system for sufficiently small damping.
Moreover, we employ the method of averaging to investigate the phenomenon of
capture into resonance.Comment: REVTEX Style, Submitte
Профилактика обострений ХОБЛ с помощью ингаляций микрочастиц металлического серебра у рабочих промышленных предприятий Ямала
Placebo controlled trial of efficacy of inhales silver micro-particles for prevention of exacerbations of chronic obstructive lung diseases (COPD) was carried out in industrial workers in Jamal. The study duration was 360 days (180 days of therapy and 180 days of follow-up without treatment). The patients (120 persons) were divided into 3 groups: the 1st group received inhalations of dry aerosol of silver micro-particles, the 2nd group was administered dry aerosol of sodium chloride (placebo), and the 3rd group did not receive any preventive treatment. In the group received silver inhalations exacerbations decreased twice, duration of exacerbations decreased to one third and the physical tolerance increased when compared to the placebo group.Среди работников промышленных предприятий Ямала проведено плацебо-контролируемое исследование эффективности ингаляций микрочастиц металлического серебра, применяемых для профилактики обострений ХОБЛ, длительностью 360 дней (180 дней ингаляции, 180 дней наблюдение). Больные (120 человек) разделены на 3 группы: получающих ингаляции сухого аэрозоля микрочастиц металлического серебра, получающих плацебо (сухой аэрозоль натрия хлорида) и группу контроля, не получающую профилактического лечения. Применение ингаляций сухого аэрозоля микрочастиц металлического серебра позволило в 2 раза снизить количество обострений, на 1 / 2 уменьшить длительность обострений по сравнению с группой плацебо и контроля и способствовало повышению толерантности к физической нагрузке, положительной динамике кашля и увеличению проходимости бронхов
A systematic review of studies measuring and reporting hearing aid usage in older adults since 1999: a descriptive summary of measurement tools
Objective: A systematic review was conducted to identify and quality assess how studies published since 1999 have
measured and reported the usage of hearing aids in older adults. The relationship between usage and other dimensions of hearing aid outcome, age and hearing loss are summarised.
Data sources: Articles were identified through systematic searches in PubMed/MEDLINE, The University of Nottingham
Online Catalogue, Web of Science and through reference checking. Study eligibility criteria: (1) participants aged fifty years or over with sensori-neural hearing loss, (2) provision of an air conduction hearing aid, (3) inclusion of hearing aid usage measure(s) and (4) published between 1999 and 2011.
Results: Of the initial 1933 papers obtained from the searches, a total of 64 were found eligible for review and were quality assessed on six dimensions: study design, choice of outcome instruments, level of reporting (usage, age, and audiometry) and cross validation of usage measures. Five papers were rated as being of high quality (scoring 10–12), 35 papers were rated as being of moderate quality (scoring 7–9), 22 as low quality (scoring 4–6) and two as very low quality (scoring 0–2). Fifteen different methods were identified for assessing the usage of hearing aids.
Conclusions: Generally, the usage data reviewed was not well specified. There was a lack of consistency and robustness in
the way that usage of hearing aids was assessed and categorised. There is a need for more standardised level of reporting of hearing aid usage data to further understand the relationship between usage and hearing aid outcomes
Orbital effects of a monochromatic plane gravitational wave with ultra-low frequency incident on a gravitationally bound two-body system
We analytically compute the long-term orbital variations of a test particle
orbiting a central body acted upon by an incident monochromatic plane
gravitational wave. We assume that the characteristic size of the perturbed
two-body system is much smaller than the wavelength of the wave. Moreover, we
also suppose that the wave's frequency is much smaller than the particle's
orbital one. We make neither a priori assumptions about the direction of the
wavevector nor on the orbital geometry of the planet. We find that, while the
semi-major axis is left unaffected, the eccentricity, the inclination, the
longitude of the ascending node, the longitude of pericenter and the mean
anomaly undergo non-vanishing long-term changes. They are not secular trends
because of the slow modulation introduced by the tidal matrix coefficients and
by the orbital elements themselves. They could be useful to indepenedently
constrain the ultra-low frequency waves which may have been indirectly detected
in the BICEP2 experiment. Our calculation holds, in general, for any
gravitationally bound two-body system whose characteristic frequency is much
larger than the frequency of the external wave. It is also valid for a generic
perturbation of tidal type with constant coefficients over timescales of the
order of the orbital period of the perturbed particle.Comment: LaTex2e, 24 pages, no figures, no tables. Changes suggested by the
referees include
A data-driven synthesis of research evidence for domains of hearing loss, as reported by adults with hearing loss and their communication partners
A number of assessment tools exist to evaluate the impact of hearing loss, with little consensus among researchers as to either preference or psychometric adequacy. The item content of hearing loss assessment tools should seek to capture the impact of hearing loss on everyday life, but to date no one has synthesized the range of hearing loss complaints from the perspectives of the person with hearing loss and their communication partner. The current review aims to synthesize the evidence on person with hearing loss- and communication partner-reported complaints of hearing loss. Searches were conducted in Cos Conference Papers Index, the Cumulative Index to Nursing and Allied Health Literature, Excerpta Medica Database, PubMed, Web of Science, and Google Scholar to identify publications from May 1982 to August 2015. A manual search of four relevant journals updated the search to May 2017. Of the 9,516 titles identified, 78 records (comprising 20,306 participants) met inclusion criteria and were taken through to data collection. Data were analyzed using meta-ethnography to form domains representing the person with hearing loss- and communication partner-reported complaints of hearing loss as reported in research. Domains and subdomains mutual to both perspectives are related to ‘‘Auditory’’ (listening, communicating, and speaking), ‘‘Social’’ (relationships, isolation, social life, occupational, and interventions), and ‘‘Self’’ (effort and fatigue, emotions, identity, and stigma). Our framework contributes fundamental new knowledge and a unique resource that enables researchers and clinicians to consider the broader impacts of hearing loss. Our findings can also be used to guide questions during diagnostic assessment and to evaluate existing measures of hearing loss
The Efficacy of Auditory Perceptual Training for Tinnitus: A Systematic Review
Auditory perceptual training affects neural plasticity and so represents a potential strategy for tinnitus management. We assessed the effects of auditory perceptual training on tinnitus perception and/or its intrusiveness via a systematic review of published literature. An electronic database search using the keywords ‘tinnitus and learning’ or ‘tinnitus and training’ was conducted, updated by a hand search. The ten studies identified were reviewed independently by two reviewers, data were extracted, study quality was assessed according to a number of specific criteria and the information was synthesised using a narrative approach. Nine out of the ten studies reported some significant change in either self-reported or psychoacoustic outcome measures after auditory training. However, all studies were quality rated as providing low or moderate levels of evidence for an effect. We identify a need for appropriately randomised and controlled studies that will generate high-quality unbiased and generalisable evidence to ascertain whether or not auditory perceptual training has a clinically relevant effect on tinnitus
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