11,326 research outputs found
Charge Violation and Alice Behavior in Global and Textured Strings
Spontaneous breaking of global symmetries can produce ``Alice'' strings: line
defects which make unbroken symmetries multivalued, induce apparent charge
violation via Aharonov-Bohm interactions, and form point defects when twisted
into loops. We demonstrate this behavior for both divergent and textured global
Alice strings. Both adiabatically scatter charged particles via effective
Wilson lines. For textured Alice strings, such Wilson lines occur at all radii,
and are multivalued only inside the string. This produces measurable effects,
including path-dependent charge violation.Comment: 32 pages, 2 epsfigs, Revte
Observations of cosmic ray induced phosphenes
Phosphene observations by astronauts on flights near and far from earth atmosphere are discussed. It was concluded that phosphenes could be observed by the naked eye. Further investigation is proposed to determine realistic human tolerance levels for extended missions and to evaluate the need to provide special spacecraft shielding
A universal ionization threshold for strongly driven Rydberg states
We observe a universal ionization threshold for microwave driven one-electron
Rydberg states of H, Li, Na, and Rb, in an {\em ab initio} numerical treatment
without adjustable parameters. This sheds new light on old experimental data,
and widens the scene for Anderson localization in light matter interaction.Comment: 4 pages, 1 figur
Fluorides, orthodontics and demineralization: a systematic review
Objectives: To evaluate the effectiveness of fluoride in preventing white spot lesion (WSL) demineralization during orthodontic treatment and compare all modes of fluoride delivery.
Data sources: The search strategy for the review was carried out according to the standard Cochrane systematic review methodology. The following databases were searched for RCTs or CCTs: Cochrane Clinical Trials Register, Cochrane Oral Health Group Specialized Trials Register, MEDLINE and EMBASE. Inclusion and exclusion criteria were applied when considering studies to be included. Authors of trials were contacted for further data.
Data selection: The primary outcome of the review was the presence or absence of WSL by patient at the end of treatment. Secondary outcomes included any quantitative assessment of enamel mineral loss or lesion depth.
Data extraction: Six reviewers independently, in duplicate, extracted data, including an assessment of the methodological quality of each trial.
Data synthesis: Fifteen trials provided data for this review, although none fulfilled all the methodological quality assessment criteria. One study found that a daily NaF mouthrinse reduced the severity of demineralization surrounding an orthodontic appliance (lesion depth difference â70.0 ”m; 95% CI â118.2 to â21.8 ”m). One study found that use of a glass ionomer cement (GIC) for bracket bonding reduced the prevalence of WSL (Peto OR 0.35; 95% CI 0.15â0.84) compared with a composite resin. None of the studies fulfilled all of the methodological quality assessment criteria.
Conclusions: There is some evidence that the use of a daily NaF mouthrinse or a GIC for bonding brackets might reduce the occurrence and severity of WSL during orthodontic treatment. More high quality, clinical research is required into the different modes of delivering fluoride to the orthodontic patient
A combinatorial smoothness criterion for spherical varieties
We suggest a combinatorial criterion for the smoothness of an arbitrary
spherical variety using the classification of multiplicity-free spaces,
generalizing an earlier result of Camus for spherical varieties of type .Comment: 14 pages, 2 table
Individual and Population Level Resource Selection Patterns of Mountain Lions Preying on Mule Deer along an Urban-Wildland Gradient
Understanding population and individual-level behavioral responses of large carnivores to human disturbance is important for conserving top predators in fragmented landscapes. However, previous research has not investigated resource selection at predation sites of mountain lions in highly urbanized areas. We quantified selection of natural and anthropogenic landscape features by mountain lions at sites where they consumed their primary prey, mule deer (Odocoileus hemionus), in and adjacent to urban, suburban, and rural areas in greater Los Angeles. We documented intersexual and individual-level variation in the environmental conditions present at mule deer feeding sites relative to their availability across home ranges. Males selected riparian woodlands and areas closer to water more than females, whereas females selected developed areas marginally more than males. Females fed on mule deer closer to developed areas and farther from riparian woodlands than expected based on the availability of these features across their home ranges.We suggest that mortality risk for females and their offspring associated with encounters with males may have influenced the different resource selection patterns between sexes. Males appeared to select mule deer feeding sites mainly in response to natural landscape features, while females may have made kills closer to developed areas in part because these are alternative sites where deer are abundant. Individual mountain lions of both sexes selected developed areas more strongly within home ranges where development occurred less frequently. Thus, areas near development may represent a trade-off for mountain lions such that they may benefit from foraging near development because of abundant prey, but as the landscape becomes highly urbanized these benefits may be outweighed by human disturbance
Ginzburg-Landau Theory for the Jaynes-Cummings-Hubbard Model
We develop a Ginzburg-Landau theory for the Jaynes-Cummings-Hubbard model
which effectively describes both static and dynamic properties of photons
evolving in a cubic lattice of cavities, each filled with a two-level atom. To
this end we calculate the effective action to first-order in the hopping
parameter. Within a Landau description of a spatially and temporally constant
order parameter we calculate the finite-temperature mean-field quantum phase
boundary between a Mott insulating and a superfluid phase of polaritons.
Furthermore, within the Ginzburg-Landau description of a spatio-temporal
varying order parameter we determine the excitation spectra in both phases and,
in particular, the sound velocity of light in the superfluid phase
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