945 research outputs found
Photogrammetry and ballistic analysis of a high-flying projectile in the STS-124 space shuttle launch
A method combining photogrammetry with ballistic analysis is demonstrated to
identify flying debris in a rocket launch environment. Debris traveling near
the STS-124 Space Shuttle was captured on cameras viewing the launch pad within
the first few seconds after launch. One particular piece of debris caught the
attention of investigators studying the release of flame trench fire bricks
because its high trajectory could indicate a flight risk to the Space Shuttle.
Digitized images from two pad perimeter high-speed 16-mm film cameras were
processed using photogrammetry software based on a multi-parameter optimization
technique. Reference points in the image were found from 3D CAD models of the
launch pad and from surveyed points on the pad. The three-dimensional reference
points were matched to the equivalent two-dimensional camera projections by
optimizing the camera model parameters using a gradient search optimization
technique. Using this method of solving the triangulation problem, the xyz
position of the object's path relative to the reference point coordinate system
was found for every set of synchronized images. This trajectory was then
compared to a predicted trajectory while performing regression analysis on the
ballistic coefficient and other parameters. This identified, with a high degree
of confidence, the object's material density and thus its probable origin
within the launch pad environment. Future extensions of this methodology may
make it possible to diagnose the underlying causes of debris-releasing events
in near-real time, thus improving flight safety.Comment: 26 pages, 11 figures, 3 table
Consensus recommendations on sleeping problems in Phelan-McDermid syndrome
Early onset sleep problems and disorders are very common in individuals with Phelan-McDermid Syndrome (PMS) with rates of up to 90%. These sleep problems and disorders cannot be taken lightly. Not only do they have a major impact on the health, behaviour, functioning and learning opportunities of affected individuals, they can also have detrimental effects on the well-being and resilience of parents and caregivers, ultimately affecting the physical health, mental health and well-being of the whole social system. In this review we aim to understand the types and frequencies of sleeping problems in PMS as the basis for recommendations on their management and treatment and to provide general guidelines for clinicians and practitioners. We conducted an in-depth literature search, summarised findings, and participated in a series of consensus meetings with other consortium members - experts on PMS and stakeholders - to agree on guidelines and recommendations. In parallel, a world-wide survey was created and distributed amongst parents to include their perspective. Our literature search found only four articles specifically focused on sleeping problems in PMS, although some other articles mentioned prevalence and associated factors. Country-specific prevalence rates ranged between 24% and 46%, whereas our parental survey reported 59%. The main problems reported involved difficulty falling asleep and numerous night awakenings, with being restless in sleep, night-time incontinence, and tooth grinding also commonly reported. Only a small number of individuals had undergone a sleep study monitored by a specialist. Bedtime resistance normally decreases with age, but sleep-onset delay, sleep anxiety, parasomnias, problems falling and remaining asleep remain throughout lifespan, with total sleep time improving during adulthood. However, this improvement was also accompanied by a substantial increase in parasomnias. Ultimately, an increase in sleep disorders in children correlates with increased sleep disorders and daytime sleepiness in parents/caregivers. No study to date has focused on the underlying causes of sleeping problems in PMS, but comorbid mental health conditions, somatic causes, or (poly)pharmacy have been proposed as triggers for sleeping disturbances. Currently there is no PMS-specific treatment for sleeping problems, and current recommendations are mostly based on individuals with intellectual disability and/or neurodevelopmental conditions.</p
Food Insecurity and Eating Disorders: A Review of Emerging Evidence
Purpose of Review: This review summarizes emerging evidence for the relationship between food insecurity and eating disorder (ED) pathology, outlines priorities for future research in this area, and comments on considerations for clinical and public health practice.
Recent Findings: Among adults, food insecurity is cross-sectionally associated with higher levels of overall ED pathology, binge eating, compensatory behaviors, binge-eating disorder, and bulimia nervosa. Evidence for similar relationships among adolescents has been less robust; however, compared to studies of adults, there have been substantially fewer studies conducted in adolescents to date.
Summary: Emerging evidence consistently indicates that food insecurity is cross-sectionally associated with bulimic-spectrum ED pathology among adults. Findings emphasize the need for ED research to include marginalized populations who have historically been overlooked in the ED field. Much more research is needed to better understand the relationship between food insecurity and ED pathology and to determine effective ways to intervene
Controlling Silver Nanoparticle Size and Morphology with Photostimulated Synthesis
Photo-induced synthesis and control over the size and shape of colloidal
silver nanoparticles is investigated in contrast to photo-stimulated
aggregation of small nanoparticles into large fractal-type structures. The
feasibility of light-driven nanoengineering which enables manipulation of the
sizes and shapes of the isolated nanoparticles is studied by varying the amount
and type of the stabilizing agent and the type of optical irradiation.Comment: 10 pages, 7 figures, 11 image
Spintronic magnetic anisotropy
An attractive feature of magnetic adatoms and molecules for nanoscale
applications is their superparamagnetism, the preferred alignment of their spin
along an easy axis preventing undesired spin reversal. The underlying magnetic
anisotropy barrier --a quadrupolar energy splitting-- is internally generated
by spin-orbit interaction and can nowadays be probed by electronic transport.
Here we predict that in a much broader class of quantum-dot systems with spin
larger than one-half, superparamagnetism may arise without spin-orbit
interaction: by attaching ferromagnets a spintronic exchange field of
quadrupolar nature is generated locally. It can be observed in conductance
measurements and surprisingly leads to enhanced spin filtering even in a state
with zero average spin. Analogously to the spintronic dipolar exchange field,
responsible for a local spin torque, the effect is susceptible to electric
control and increases with tunnel coupling as well as with spin polarization.Comment: 6 pages with 4 figures + 26 pages of Supplementary Informatio
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