35,397 research outputs found
Planetary atlases
Two kinds of planetary map atlases are in production. Atlases of the first kind contain reduced-scale versions of maps in hard-bound books with dimensions of 11 x 14 inches. These new atlases are intended to: (1) provide concise but comprehensive references to the geography of the planets needed by planetary scientists and others; and (2) allow inexpensive access to the planetary map dataset without requiring acquisition and examination of tens or hundreds of full-size map sheets. Two such atlases have been published and a third is in press. Work was begun of an Atlas of the Satellite of the Outer Planets. The second kind of atlas is a popular or semi-technical version designed for commercial publication and distribution. The first edition, The Atlas of the Solar System, is nearly ready for publication. New funding and contracting constraints now make it unlikely that the atlas can be published in the format originally planned. Currently, the possibility of publishing the maps through the U.S. Geological Survey as a series of folios in the I-map series is being explored. The maps are global views of each solid-surface body of the Solar System. Each map shows airbrushed relief, albedo, and, where available, topography. A set of simplified geologic maps is also included. All of the maps are on equal-area projections. Scales are 1:40,000,000 for the Earth and Venus; 1:2,000,000 for the Saturnian satellites Mimas and Enceladus and the Uranian satellite Miranda; 1:100,000 for the Martian satellites, Phobos and Deimos; and 1:10,000,000 for all other bodies
LINEAR FEATURES IN PHOTOGRAMMETRY
Traditional photogrammetric activities such as orientation, triangulation, and object
space reconstruction have been relying on distinct points in their underlying
operations. With the evolution of digital photogrammetry, there has been a
tremendous interest in utilizing linear features in various photogrammetric
activities. This interest has been motivated by the fact that the extraction of linear
features from the image space is easier to automate than distinct points. On the other
hand, object space linear features can be directly derived form terrestrial Mobile
Mapping Systems (MMS), GIS databases, and/or existing maps. Moreover,
automatic matching of linear features, either within overlapping images or between
image and object space, is easier than that of distinct points. Finally, linear features
possess more semantic information than distinct points since they most probably
correspond to object boundaries. Such semantics can be automatically identified in
imagery to facilitate higher-level tasks (e.g., surface reconstruction and object
recognition). This paper summarizes the use of linear features, which might be
represented by analytical functions (e.g., straight-line segments) or irregular (freeform)
shapes, in photogrammetric activities such as automatic space resection,
photogrammetric triangulation, camera calibration, image matching, surface
reconstruction, image-to-image registration, and absolute orientation. Current
progress, future expectations, and possible research directions are discussed as well
The Isoperimetric Profile of a Noncompact Riemannian Manifold for Small Volumes
In the main theorem of this paper we treat the problem of existence of
minimizers of the isoperimetric problem under the assumption of small volumes.
Applications of the main theorem to asymptotic expansions of the isoperimetric
problem are given.Comment: 33 pages, improved version after the referee comments, (Submitted
Anisotropic Scaling in Layered Aperiodic Ising Systems
The influence of a layered aperiodic modulation of the couplings on the
critical behaviour of the two-dimensional Ising model is studied in the case of
marginal perturbations. The aperiodicity is found to induce anisotropic
scaling. The anisotropy exponent z, given by the sum of the surface
magnetization scaling dimensions, depends continuously on the modulation
amplitude. Thus these systems are scale invariant but not conformally invariant
at the critical point.Comment: 7 pages, 2 eps-figures, Plain TeX and epsf, minor correction
Perspectives on financial incentives to health service providers for increasing breast feeding and smoking quit rates during pregnancy: a mixed methods study
Objective: To explore the acceptability, mechanisms and consequences of provider incentives for smoking cessation and breast feeding as part of the Benefits of Incentives for Breastfeeding and Smoking cessation in pregnancy (BIBS) study.
Design: Cross-sectional survey and qualitative interviews.
Setting: Scotland and North West England.
Participants: Early years professionals: 497 survey respondents included 156 doctors; 197 health visitors/maternity staff; 144 other health staff. Qualitative interviews or focus groups were conducted with 68 pregnant/postnatal women/family members; 32 service providers; 22 experts/decision-makers; 63 conference attendees.
Methods: Early years professionals were surveyed via email about the acceptability of payments to local health services for reaching smoking cessation in pregnancy and breastfeeding targets. Agreement was measured on a 5-point scale using multivariable ordered logit models. A framework approach was used to analyse free-text survey responses and qualitative data.
Results: Health professional net agreement for provider incentives for smoking cessation targets was 52.9% (263/497); net disagreement was 28.6% (142/497). Health visitors/maternity staff were more likely than doctors to agree: OR 2.35 (95% CI 1.51 to 3.64; p<0.001). Net agreement for provider incentives for breastfeeding targets was 44.1% (219/497) and net disagreement was 38.6% (192/497). Agreement was more likely for women (compared with men): OR 1.81 (1.09 to 3.00; p=0.023) and health visitors/maternity staff (compared with doctors): OR 2.54 (95% CI 1.65 to 3.91; p<0.001). Key emergent themes were 'moral tensions around acceptability', 'need for incentives', 'goals', 'collective or divisive action' and 'monitoring and proof'. While provider incentives can focus action and resources, tensions around the impact on relationships raised concerns. Pressure, burden of proof, gaming, box-ticking bureaucracies and health inequalities were counterbalances to potential benefits.
Conclusions: Provider incentives are favoured by non-medical staff. Solutions which increase trust and collaboration towards shared goals, without negatively impacting on relationships or increasing bureaucracy are required
Laboratory Study Of Frequency Dependent Streaming Potentials
Frequency dependent streaming potentials were measured on a glass capillary, porous
filter, and a sample of Boise sandstone. The pore diameters for these three samples
range from 1 millimeter to 34 micrometers. The frequencies used in these experiments
range from 0-600 Hz with the critical frequencies being 6.8 Hz, 90 Hz, and 400 Hz
for the three specimens. The fluid was moved relative to the sample with the pressure
measured by hydrophones and the streaming potential measured using silver silverchloride
electrodes. Both Packard's (1953) and Pride's (1994) models satisfactorily
predict the streaming potential behavior for these frequencies, and the measured critical
frequencies are directly related to the sample pore diameters.United States. Air Force Office of Scientific Research (Grant F49620-95-1-0224)Massachusetts Institute of Technology. Borehole Acoustics and Logging ConsortiumMassachusetts Institute of Technology. Earth Resources Laboratory. Reservoir Delineation
Consortiu
Addressing student models of energy loss in quantum tunnelling
We report on a multi-year, multi-institution study to investigate student
reasoning about energy in the context of quantum tunnelling. We use ungraded
surveys, graded examination questions, individual clinical interviews, and
multiple-choice exams to build a picture of the types of responses that
students typically give. We find that two descriptions of tunnelling through a
square barrier are particularly common. Students often state that tunnelling
particles lose energy while tunnelling. When sketching wave functions, students
also show a shift in the axis of oscillation, as if the height of the axis of
oscillation indicated the energy of the particle. We find inconsistencies
between students' conceptual, mathematical, and graphical models of quantum
tunnelling. As part of a curriculum in quantum physics, we have developed
instructional materials to help students develop a more robust and less
inconsistent picture of tunnelling, and present data suggesting that we have
succeeded in doing so.Comment: Originally submitted to the European Journal of Physics on 2005 Feb
10. Pages: 14. References: 11. Figures: 9. Tables: 1. Resubmitted May 18 with
revisions that include an appendix with the curriculum materials discussed in
the paper (4 page small group UW-style tutorial
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