12,276 research outputs found
Informal names for surface features in the Apollo 15 landing area
Informal names and descriptions of lunar topographic features in Apollo 15 landing regio
Some geologic observations concerning lunar geophysical models
The distribution of lunar geologic units in space and time and their mode of origin were considered since they provided significant data which bear on a number of current problems in lunar geophysics. Observations and problems were discussed which deal with the characterization of the upper 25 km of the lunar crust, the tectonic style of the crust, the formation of mascons within major basins, analysis of lunar magnetic anomalies, and the history of the lunar crust
Derivation of topographic feature names in the Apollo 15 landing region
Location and derivation of nomenclature for lunar topographic features in Apollo 15 landing regio
Significant achievements in the planetary geology program, 1975 - 1976
Developments in planetology research as reported at the 1976 NASA Planetology Program Principal Investigators' meeting are summarized. Topics range from solar system evolution, comparative planetology, and geologic processes to techniques and instrument development for future exploration
The Anisotropic Bak-Sneppen model
The Bak-Sneppen model is shown to fall into a different universality class with the introduction of a preferred direction, mirroring the situation in spin systems. This is first demonstrated by numerical simulations and subsequently confirmed by analysis of the multitrait version of the model, which admits exact solutions in the extremes of zero and maximal anisotropy. For intermediate anisotropies, we show that the spatiotemporal evolution of the avalanche has a power law `tail' which passes through the system for any non-zero anisotropy but remains fixed for the isotropic case, thus explaining the crossover in behaviour. Finally, we identify the maximally anisotropic model which is more tractable and yet more generally applicable than the isotropic system
Telehealth in Palliative Care: A Systematic Review of Patient Reported Outcomes
A systematic review was conducted to explore published quantitative and qualitative research describing patient-reported outcomes of palliative telehealth intervention studies. Multiple databases were searched for articles published between January 2006 and May 2016, which met study criteria. Methodological quality was assessed using Cochrane Collaboration’s tool for assessing risk of bias for quantitative articles. For studies reporting qualitative outcomes, a checklist was used to evaluate trustworthiness of the methodology. Of the 6 studies reporting quantitative outcomes, 3 studies were rated as having moderate study quality, and 3 studies were rated as having low study quality. Of the 6 studies reporting qualitative outcomes, 3 reported 5 different methods for ensuring trustworthiness, whereas 1 article reported 4 methods, 1 reported 3, and 1 article reported 2 methods. Studies were notably diverse in terms of patient population, technology used, outcomes measures, and methodology. Results across studies were also variable. Methodological factors were major limitations. Recruitment problems, participant attrition, and lack of standardized outcomes measures impacted outcome assessment. Overall, research support for positive patient outcomes in palliative telehealth interventions was weak. However, all studies but one found positive results to support the intervention
A Systematic Review of Telehealth in Palliative Care: Caregiver Outcomes
Objective: Telehealth interventions have proven efficacy in healthcare, but little is known about the results of such interventions in palliative care. We conducted a systematic review to evaluate caregiver outcomes related to palliative telehealth interventions. Materials and Methods: We searched multiple databases for articles published between January 2003 and January 2015 related to telehealth in palliative care. Two hundred twenty-one articles were considered; nine of these met study inclusion criteria. Data on study design, population, interventions, methods, outcomes, conclusions, and methodological quality were extracted and evaluated by three investigators. Results: Of the nine studies, five measured caregiver quality of life, three measured caregiver anxiety, and two measured caregiver burden. All the studies measuring caregiver quality of life showed no significant difference after telehealth interventions. The caregiver anxiety score decreased after the intervention in two studies, and one study reported significantly reduced caregiver burden. Although feasibility of or caregiver satisfaction with the telehealth intervention was not the focus of this review, most studies reported such findings. Of the nine studies, the majority were rated as having moderate quality using the Cochrane Collaboration’s tool for assessing risk of bias. Conclusions: This systematic review suggests there is evidence of overall satisfaction in caregivers who undergo a telehealth intervention, but outcomes reported were often not substantial. Methodological flaws and small sample sizes negatively affected study quality. More rigorous research to test and evaluate such palliative interventions is needed
Microscopic basis for pattern formation and anomalous transport in two-dimensional active gels
Active gels are a class of biologically-relevant material containing embedded
agents that spontaneously generate forces acting on a sparse filament network.
In vitro experiments of protein filaments and molecular motors have revealed a
range of non- equilibrium pattern formation resulting from motor motion along
filament tracks, and there are a number of hydrodynamic models purporting to
describe such systems. Here we present results of extensive simulations
designed to elucidate the microscopic basis underpinning macroscopic flow in
active gels. Our numerical scheme includes thermal fluctuations in filament
positions, excluded volume interactions, and filament elasticity in the form of
bending and stretching modes. Motors are represented individually as bipolar
springs governed by rate-based rules for attachment, detachment and
unidirectional motion of motor heads along the filament contour. We
systematically vary motor density and speed, and uncover parameter regions
corresponding to unusual statics and dynamics which overlap but do not
coincide. The anomalous statics arise at high motor densities and take the form
of end-bound localized filament bundles for rapid motors, and extended clusters
exhibiting enhanced small-wavenumber density fluctuations and power-law
cluster-size distributions for slow, processive motors. Anomalous dynamics
arise for slow, processive motors over a range of motor densities, and are most
evident as superdiffusive mass transport, which we argue is the consequence of
a form of effective self-propulsion resulting from the polar coupling between
motors and filaments.Comment: 14 pages, 17 figures. Minor clarifications and updated/additional
references. To appear in Soft Matte
Rift systems on Venus: An assessment of mechanical and thermal models
The formation and distribution of major tectonic features on Venus are closely linked to the dominant mechanism of lithospheric heat loss. Among the most spectacular and extensive of the major tectonic features on Venus are the Chasmata, deep linear valleys generally interpreted to be the products of lithospheric extension and rifting. Systems of chasmata and related features can be traced along several tectonic zones up to 20,000 km in linear extent. Mechanical and thermal models for terrestrial continental-rifting are applied to the rift systems of Venus. The models are tested against known topographic and tectonic characteristics of Venus chasmata as well as independent information on the physical properties of the Venus crust and lithosphere
The distribution and modes of occurrence of impact melt at lunar craters
Numerous studies of the returned lunar samples as well as geologic and remote-sensing investigations have emphasized the importance of impact melts on the surface of the Moon. Information concerning the distribution and relative volumes is important for (1) an improved understanding of cratering processes, (2) kinetic energy estimates and energy partitioning studies, (3) the proper interpretation of melt-bearing lunar samples, and (4) comparative planetology studies. The identification of major flows of fluidized material associated with impact craters on the surface of Venus has increased interest in impact melt flows on the other terrestrial planets. For a number of years, we have been investigating the distribution, modes of occurrence, and relative and absolute amounts of impact melt associated with lunar craters as well as the manner in which melt volumes vary as a function of crater size, morphology, and target characteristics. The results of this effort are presented
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