51,305 research outputs found
New experimental limits on violations of the Pauli exclusion principle obtained with the Borexino Counting Test Facility
No full textThe Pauli exclusion principle (PEP) has been tested for nucleons (n,p) in 12C and 16O nuclei, using the results of background measurements with the prototype of the Borexino detector, the Counting Test Facility (CTF). The approach consisted of a search for γ, n, p and/or α's emitted in a non-Paulian transition of 1P- shell nucleons to the filled 1S1/2 shell in nuclei. Similarly, the Pauli-forbidden β± decay processes were searched for. Due to the extremely low background and the large mass (4.2 tons) of the CTF detector, the following most stringent up-to-date experimental bounds on PEP violating transitions of nucleons have been established: τ(12C→12C ̃+γ)>2.1⋅1027 y, τ(12C→11B ̃+p)>5.0⋅1026 y, τ(12C(16O)→11C ̃(15O ̃)+n)>3.7⋅1026 y, τ(12C→8Be ̃+α)>6.1⋅1023 y, τ(12C→12N ̃+e−+νe ̃)>7.6⋅1027 y and τ(12C→12B ̃+e++νe)>7.7⋅1027 y, all at 90% C.L
Analise de viabilidade para o projeto de poltronas de passageiros para a aviação regional
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina. Centro TecnologicoAproveitou-se uma experiência profissional na indústria de poltronas de passageiros para a aviação comercial para formar a base de uma investigação sobre a etapa de Análise de Viabilidade para o projeto de produtos. Constam deste trabalho a análise do mercado e suas necessidades, a análise das soluções técnicas dos produtos concorrentes, o estudo de uma oportunidade tecnológica e o estudo de viabilidade das soluções alternativas geradas para o projeto
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Resolution of front-back confusion in virtual acoustic imaging systems
No full textA geometric model of the scattering of sound by the human head is used to generate a model of localization cues based on interaural time delay (ITD). The ITD is calculated in terms of the interaural cross-correlation function (IACC) for sources placed at a series of azimuthal angles in the horizontal plane. This model is used to simulate the pressures generated at the ears of a listener due to real sources and due to a two-channel and a four-channel virtual source imaging system. Results are presented in each case for the variation of ITD with head rotation. The simulations predict that the rate of change of the ITD with head rotation produced by a real source and replicated by the four-channel virtual source imaging system, cannot be replicated by the two-channel system. These changes to the ITD provide cues which allow resolution of front–back confusion. The results of subjective experiments are also presented for the three cases modeled. These results strongly support the findings from the modeling work indicating that, for the systems described here, front–back confusion is resolved through changes to the ITD arising from head motion
Charles H. Reed, approximately 1864-1866
No full textCarte-de-visite portrait of Charles H. Reed (Norwich University Class of 1866), approximately 1864-1866, from a disassembled Alpha Sigma Pi photograph album.Photographed by H. O. Bly, 25 Main St., Hanover, N. H. Canceled tax stamp on back
Desenvolvimento de infra-estrutura para o estudo dos efeitos da oscilação longitudinal da tocha de soldagem (Switch Back) e avaliação de desempenho no processo TIG Autógeno
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Mecânica, Florianópolis, 2015.A produção industrial está em contínua exigência por processos cada vez mais produtivos. No caso da soldagem este aumento de produtividade, não necessariamente é alcançado por meio de novos processos, mas frequentemente pela implementação de técnicas especiais nos processos considerados tradicionais. Estas técnicas, não só consideram atuação na forma de controle da energia de soldagem e atuação na tecnologia das tochas de soldagem, mas também se baseiam muito na atuação na trajetória de soldagem. Este trabalho atua neste último flanco, buscando condições de infraestrutura para estudar o efeito de um tipo de trajetória denominada de movimento de switch back. Esta consiste em oscilar a tocha na direção longitudinal do cordão de solda, via os movimentos de avanço e de retrocesso. Como o Laboratório de Soldagem da UFSC (LABSOLDA) não possuía equipamentos que realizassem tal movimento, uma vez que os robôs industriais presentes no laboratório também não possuem esta capacitação, o presente trabalho se propõe a criar esta infraestrura de desenvolvimento. No caso em questão, foi realizado o retrofitting de um antigo robô antropomórfico industrial, RV-15 fabricado em 1987 pela Reis Robotics, o readequando eletronicamente e desenvolvendo um novo controlador de movimento "open source", que permite a geração simplificada de trajetórias de oscilação diferenciadas, sincronizadas com sinais para a fonte de soldagem. O trabalho realizado no robô demonstrou ser eficaz e permitiu um estudo confiável do processo TIG autógeno com o movimento de switch back. Os ensaios revelaram que tal oscilação mostra-se como uma alternativa para a diminuição de defeitos de descontinuidade. Abstract : Industrial production is in continuous demand for more productive processes. When it comes to welding this increase in productivity is not necessarily achieved through new processes, but often by implementation of special techniques in traditional processes. These techniques not only consider to act in the form of welding power control and in the welding torches technology, but also rely heavily on acting in the welding path. This work focuses on building infrastructure conditions to study the effect of a path type, known as switch back motion. This consists in oscillating the torch in the longitudinal direction of the weld bead, via forward and backward movements. As the UFSC Welding Laboratory (LABSOLDA) did not have an equipment to perform such movement, since available industrial robots are not also able to, this paper proposes to create this development infrastructure. In this case, a retrofitting of an old industrial anthropomorphic robot RV-15 manufactured in 1987 by Reis Robotics was performed, adapting it electronically and developing a new "open source" motion controller, which enables simplified generation of differentiated oscillation trajectories synchronized with signals to the welding source. The work on the robot has proved to be effective and allowed a reliable study of autogenous TIG process with the switch back movement. The tests revealed that this oscillation is shown as an alternative for reducing discontinuity defects
Conservative management of low back pain
No full textBack pain is prevalent worldwide, but back pain disability has reached epidemic proportions in many industrialised societies. Few patients have serious medical pathology or direct neurological involvement requiring surgery. Although the causes remain unclear, physical stress and its consequences on discs, facet joints and supporting soft tissues at work or leisure are important, sometimes aggravated by adverse psychosocial factors. Modern management emphasises the role of self-care, beginning in primary care with the first episode. Without root compression, bed rest should not exceed 48 hours. Emphasis is on encouraging a rapid return to physical fitness and other activities, including employment, acknowledging that returning to a normal life may require working through pain. Medication facilitates this. No one should remain in pain beyond six weeks without being referred to a specialist service for a physical and psychosocial assessment by appropriately trained professionals and with consultant support for investigation, pain management and rehabilitation when needed
Low back pain and risk factors for low back pain in car drivers
No full textThe cause of low back pain in populations of professional drivers is uncertain. A literature review
revealed factors that seem to be associated with low back pain (e.g. physical factors: exposure to
whole body-vibration, prolonged sitting posture, frequent lifting, pushing and pulling, lack of physical
fitness; psychosocial factors: job satisfaction or stress; individual factors: age, gender,
anthropometrics, tobacco, alcohol consumption, etc.).
This thesis investigates the occurrence of back pain in professional car drivers – a group found to
be not focussed upon in previous epidemiological studies. The thesis seeks to advance
understanding of response relationships between risk factors and low back pain in populations of
car drivers (209 taxi drivers and 365 police drivers) and 485 non-drivers. A longitudinal study with
cross-sectional baseline combined with field measurement of driving in selected vehicles was
performed to investigate the occurrence of musculoskeletal problems (mainly low back pain) and
the relationship between risk factors and low back pain experienced for at least one day during the
past 12 months in the two populations of professional drivers (taxi drivers and police drivers) and
professional non-drivers.
The cross-sectional baseline of the longitudinal study revealed that 45% (38.3-51.7%) of taxi
drivers, 53% (48-58.6%)of police drivers and 46% (41-50.1%) of police non-drivers reported low
back pain for at least one day during the past 12-months (p = 0.09). The prevalence of low back
pain in the non-driving population of police employees fell within prevalence range reported by
professional car drivers in this study and in previous epidemiological studies. The cross-sectional
study revealed risk factors associated with the prevalence of low back pain (i.e., stature, previous
physical demands, increased psychosomatic distress, daily and cumulative driving in taxi drivers;
age, lifting, bending, increase psychosomatic distress in police drivers; stature, bending, increased
psychosomatic distress in police non-drivers).
Measurements of whole-body vibration in selected taxi and police vehicles revealed frequencyweighted
accelerations in the dominant vibration direction (i.e., z-axis) to be 0.47 ms-2 r.m.s. in taxi
vehicles and 0.58 ms-2 r.m.s. in police vehicles.
A study of cumulative exposure to whole-body vibration in a group of taxi drivers pointed to a
possible overestimation of their self-estimated duration of vibration exposure by 31% on average.
The longitudinal study revealed a lower incidence of low back pain in taxi drivers than in both
police drivers and police non-drivers (p = 0.02). The difference might be attributed to a different
approach to low back pain in taxi drivers who lose income if unable to work. An alternative
explanation for increased low back pain among police employees could be that taxi drivers with low
back pain leave their profession and were excluded from the follow-up study – a healthy worker
effect.
The longitudinal study revealed that increased psychosomatic distress was a risk factor
associated with the development of new episodes of low back pain in all three of the studied
populations (i.e. taxi drivers and police drivers and non-drivers).
In police drivers, increased daily duration of driving was a risk factor for the development of low
back pain. Although the results point to increased incidence of low back pain with increasing
duration of daily driving, non-drivers were at a similar risk of developing of low back pain. Plausible
explanations for this finding include ergonomic factors that were present for both the drivers and the
non-drivers (e.g., the duration of sitting or duration in a constrained posture) and the presence of
other risk factors not investigated in the study but associated with increased incidence of low back
pain in non-drivers
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Design considerations in a clinical trial of a cognitive behavioural intervention for the management of low back pain in primary care : Back Skills Training Trial
No full textBackground
Low back pain (LBP) is a major public health problem. Risk factors for the development and persistence of LBP include physical and psychological factors. However, most research activity has focused on physical solutions including manipulation, exercise training and activity promotion.
Methods/Design
This randomised controlled trial will establish the clinical and cost-effectiveness of a group programme, based on cognitive behavioural principles, for the management of sub-acute and chronic LBP in primary care. Our primary outcomes are disease specific measures of pain and function. Secondary outcomes include back beliefs, generic health related quality of life and resource use. All outcomes are measured over 12 months. Participants randomised to the intervention arm are invited to attend up to six weekly sessions each of 90 minutes; each group has 6–8 participants. A parallel qualitative study will aid the evaluation of the intervention.
Discussion
In this paper we describe the rationale and design of a randomised evaluation of a group based cognitive behavioural intervention for low back pain
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