2,621 research outputs found
A model of human event detection in multiple process monitoring situations
It is proposed that human decision making in many multi-task situations might be modeled in terms of the manner in which the human detects events related to his tasks and the manner in which he allocates his attention among his tasks once he feels events have occurred. A model of human event detection performance in such a situation is presented. An assumption of the model is that, in attempting to detect events, the human generates the probability that events have occurred. Discriminant analysis is used to model the human's generation of these probabilities. An experimental study of human event detection performance in a multiple process monitoring situation is described and the application of the event detection model to this situation is addressed. The experimental study employed a situation in which subjects simulataneously monitored several dynamic processes for the occurrence of events and made yes/no decisions on the presence of events in each process. Input to the event detection model of the information displayed to the experimental subjects allows comparison of the model's performance with the performance of the subjects
The Effects of a Closed-Chain, Eccentric Training Program on Hamstring Injuries of a Professional Football Cheerleading Team
Objective Hamstring injuries are a common occurrence among professional football cheerleaders. The purpose of this study is to identify the effects of an eccentric, closed-chain hamstring exercise intervention on hamstring injury–associated pain during the course of the football season among professional football cheerleaders. Methods Forty-three female cheerleaders participated in an eccentric, closed-chain hamstring exercise intervention protocol provided by doctors of chiropractic that incorporated loops of elastic-band or Thera-Band Loops (Hygenic Corporation, Akron, OH) during practice and at home during the regular football season. Hamstring injury–related pain was assessed in June, during team selection; in September, at the start of the season; and in December, at the end of season. No intervention was applied between June and September, although the sample participated in 4 hours of practice 2 to 3 times per week. The intervention was applied to the entire sample regardless of hamstring injury–related pain during the regular football season between September and December. The interventions included 2 exercises and were completed bilaterally 2 times per week at each biweekly practice and were encouraged to be done at least 3 additional times per week at home on nonpractice days. Results Among the subsample who reported hamstring-related injury pain between June and September, the exercise intervention significantly decreased (P \u3c .007) pain between September (6.07 ± 0.58) and December (3.67 ± 0.65). Conclusions The eccentric, closed-chain hamstring exercise intervention reduced hamstring injury–related pain among this group of professional football cheerleaders
Pilot interaction with automated airborne decision making systems
An investigation was made of interaction between a human pilot and automated on-board decision making systems. Research was initiated on the topic of pilot problem solving in automated and semi-automated flight management systems and attempts were made to develop a model of human decision making in a multi-task situation. A study was made of allocation of responsibility between human and computer, and discussed were various pilot performance parameters with varying degrees of automation. Optimal allocation of responsibility between human and computer was considered and some theoretical results found in the literature were presented. The pilot as a problem solver was discussed. Finally the design of displays, controls, procedures, and computer aids for problem solving tasks in automated and semi-automated systems was considered
Sleep Characteristics in Patients with Whiplash-Associated Disorders: A Descriptive Study
Study Objectives: The purpose of this study was to explore sleep habits and characteristics of patients with whiplash-associated disorders (WAD) presenting at an outpatient, chiropractic clinic using the Medical Outcomes Study (MOS) Sleep Scale.
Methods: Fifty-one patients from an outpatient chiropractic and physical therapy clinic specializing in spinal rehabilitation participated in this cross-sectional, descriptive study. Data were collected using a descriptive survey, the Visual Analog Scale (VAS), the Neck Disability Index (NDI), and the self-administered 12-item MOS Sleep Scale. Data analysis included descriptive statistics to describe pain, disability, and sleep characteristics of the study sample, and computation of confidence intervals to determine differences in means of sleep characteristics between the non-WAD population (as determined by previous studies) and the study sample of WAD patients.
Results: Results indicate that when compared to normative values of the non-WAD population, the sample of WAD patients in this study presents with significantly greater measures of neck disability (NDI), neck pain (VAS), sleep disturbance, snoring, shortness of breath and headache, sleep somnolence and sleep problems index I and II. This sample also presents with significantly lower measures of optimal sleep when compared to the general population.
Conclusion: Consistent with previous research, findings from this study indicate that WAD patients have increased neck disability and pain, and poorer sleep outcomes, indicating the need for clinicians to assess sleep characteristics and incorporate interventions aimed at alleviating these symptoms when planning rehabilitation. Findings provide evidence for the need to further explore sleep disturbances among WAD patients to establish a stronger understanding of the course and prognosis of this condition
Stationary components of HeI in strong magnetic fields - a tool to identify magnetic DB white dwarfs
In only three of the 61 known magnetic white dwarfs helium has been
identified unambiguously while about 20% of all non-magnetic stars of this
class are known to contain HeI or HeII. Until recently, data for HeI data were
available only for magnetic fields below 20MG. This changed with the
publication of extensive data by the group in Heidelberg. The corresponding
calculations have now been completed for the energetically lowest five states
of singlet and triplet symmetry for the subspaces with |m| <= 3; selected
calculations have been performed for even higher excitations. In strongly
magnetized white dwarfs only line components are visible whose wavelengths vary
slowly with respect to the magnetic field, particularly stationary components
which have a wavelength minimum or maximum in the range of the magnetic fields
strengths on the stellar surface. In view of the many ongoing surveys finding
white dwarfs we want to provide the astronomical community with a tool to
identify helium in white dwarfs for fields up to 5.3GG. To this end we present
all calculated helium line components whose wavelengths in the UV, optical, and
near IR vary slowly enough with respect to the field strength to produce
visible absorption features. We also list all stationary line components in
this spectral range. Finally, we find series of minima and maxima which occur
as a result of series of extremal transitions to increasingly higher
excitations. We estimated the limits for 8 series which can possibly give rise
to additional absorption in white dwarf spectra; one strong absorption feature
in GD229 which is yet unexplained by stationary components is very close to two
estimated series limits.Comment: 8 pages, 2 figures, accepted for publication by Astronomy and
Astrophysic
Classification of Very Red Stars Using Narrowband Colors
A classification technique for faint, very red stars is described, based on two composite colors, derived from flux measurements in six narrowbands in the visual and red parts of the spectrum. One of the composite colors, ST, is an M spectral type indicator, common to both dwarfs and giants. It can be used to predict the spectral types to within half a class. The other color, DG, is a dwarf-giant discriminator for spectral types later than about M4, and whose power increases for the later types, where most other methods fail. It reflects the differences in blanketing between the late-M type dwarfs and the giants. The method can be generalized to other, similar colors, depending on the data and task at hand. It should be useful in surveys for extreme low-mass dwarfs, or alternatively, for luminous red giants, or other kinds of objects. We illustrate the application of the method on an example of a very red star identified earlier by Blair and Long, and show it to be a distant red giant
Teaching and understanding of quantum interpretations in modern physics courses
Just as expert physicists vary in their personal stances on interpretation in
quantum mechanics, instructors vary on whether and how to teach interpretations
of quantum phenomena in introductory modern physics courses. In this paper, we
document variations in instructional approaches with respect to interpretation
in two similar modern physics courses recently taught at the University of
Colorado, and examine associated impacts on student perspectives regarding
quantum physics. We find students are more likely to prefer realist
interpretations of quantum-mechanical systems when instructors are less
explicit in addressing student ontologies. We also observe contextual
variations in student beliefs about quantum systems, indicating that
instructors who choose to address questions of ontology in quantum mechanics
should do so explicitly across a range of topics.Comment: 18 pages, references, plus 2 pages supplemental materials. 8 figures.
PACS: 01.40.Fk, 03.65.-
Indistinguishability and Interference in the Coherent Control of Atomic and Molecular Processes
The subtle and fundamental issue of indistinguishability and interference
between independent pathways to the same target state is examined in the
context of coherent control of atomic and molecular processes, with emphasis
placed on possible "which-way" information due to quantum entanglement
established in the quantum dynamics. Because quantum interference between
independent pathways to the same target state occurs only when the independent
pathways are indistinguishable, it is first shown that creating useful
coherence (as defined in the paper) between nondegenerate states of a molecule
for subsequent quantum interference manipulation cannot be achieved by
collisions between atoms or molecules that are prepared in momentum and energy
eigenstates. Coherence can, however, be transferred from light fields to atoms
or molecules. Using a particular coherent control scenario, it is shown that
this coherence transfer and the subsequent coherent phase control can be
readily realized by the most classical states of light, i.e., coherent states
of light. It is further demonstrated that quantum states of light may suppress
the extent of phase-sensitive coherent control by leaking out some which-way
information while "incoherent interference control" scenarios proposed in the
literature have automatically ensured the indistinguishability of multiple
excitation pathways. The possibility of quantum coherence in photodissociation
product states is also understood in terms of the disentanglement between
photodissociation fragments. Results offer deeper insights into quantum
coherence generation in atomic and molecular processes.Comment: 26 pages, based on one Chapter from first author's Ph.D thesis in
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The Apoptotic Effects of Methylparaben and Ultraviolet B Light on M624 Human Melanoma Cells
Methylparaben is a commonly used antimicrobial in cosmetics that has been shown to have negative effects on mammalian cells. Human melanoma M624 cells were treated with 1 and 5 mM methylparaben in the presence and absence of 25 mJ/cm2 ultraviolet B (UV-B) light. Cell proliferation assays showed that 5 mM methylparaben was toxic to M624 cells after 24 hours. Apoptotic signaling pathways were analyzed via isolation of separate cellular compartments and protein analysis via western blot. Upon 5 mM methylparaben treatment, PARP I was cleaved indicating apoptosis, which was mediated by the TNF-α receptor activated in the lipid rafts of the M624 cells. Upon 25 mJ/cm2 UV-B radiation, PARP II was activated indicating cellular damage, cytochrome c was released from the mitochondria, and caspase-3 was expressed. Upon combinatory treatment with 5 mM methylparaben and 25 mJ/cm2 UV-B, apoptosis was induced through mitochondrial release of cytochrome c, expression of caspase-3 and cleavage of PARP I, while methylparaben-induced TNF-α receptor activation and UV-B-induced PARP II activation was inhibited., demonstrating that antimicrobial methylparaben in cosmetics can cause damage to cells
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