2,193 research outputs found
Dimension Spectra of Lines
This paper investigates the algorithmic dimension spectra of lines in the
Euclidean plane. Given any line L with slope a and vertical intercept b, the
dimension spectrum sp(L) is the set of all effective Hausdorff dimensions of
individual points on L. We draw on Kolmogorov complexity and geometrical
arguments to show that if the effective Hausdorff dimension dim(a, b) is equal
to the effective packing dimension Dim(a, b), then sp(L) contains a unit
interval. We also show that, if the dimension dim(a, b) is at least one, then
sp(L) is infinite. Together with previous work, this implies that the dimension
spectrum of any line is infinite
Dissipative Transport of a Bose-Einstein Condensate
We investigate the effects of impurities, either correlated disorder or a
single Gaussian defect, on the collective dipole motion of a Bose-Einstein
condensate of Li in an optical trap. We find that this motion is damped at
a rate dependent on the impurity strength, condensate center-of-mass velocity,
and interatomic interactions. Damping in the Thomas-Fermi regime depends
universally on the disordered potential strength scaled to the condensate
chemical potential and the condensate velocity scaled to the peak speed of
sound. The damping rate is comparatively small in the weakly interacting
regime, and the damping in this case is accompanied by strong condensate
fragmentation. \textit{In situ} and time-of-flight images of the atomic cloud
provide evidence that this fragmentation is driven by dark soliton formation.Comment: 14 pages, 20 figure
Carriage of Haemophilus influenzae in Cape Town children
Little is known about the epideIDiology of Haemophilus influenzae infections in South Africa. This study was designed to determine the prevalence, serotype distribution, antimicrobial susceptibility pattern and effect of age and hospitalisation on the carriage of H. influenzae in 322 Cape Town children.The overall and type b specific carriage rates in normal children (N =107) were 45,8% and 4,7% respectively. The yield following nasopharyngeal culture was twice that following throat culture (P < 0,001). Children hospitalised with tuberculosis (N =62) had significantly greater carriage rates, 66,1% and 37,1% respectively (P =0,02). Institutionalised mentally handicapped children (N =77) and children with tuberculosis attending an outpatient clinic (N =76) had lower carriage rates (P < 0,02). Antimicrobial resistance was a major problem only in children hospitalised with tuberculosis (rifampicin 100%, penicillin 43,9%, erythromycin 85,4%, co-trimoxazole 82,9%). This universal resistance to rifampicin has not been reported previously. There was no difference in the mean age of children with positive or negative cultures, with the exception of those hospitalised with tuberculosis. In this group children infected with type b were much younger (mean 19,7 months) than those with other and non-typeableinfections (32,1 months) and the non-infected(50,1 months) (P =0,04). Duration of hospitalisation or outpatient therapy in the patients with tuberculosis did not influence carriage rates.We conclude that carriage of H. influenzae in normal children is similar to that reported from other countries and that carriage, particularly of type b, in children hospitalised with tuberculosis was of significance and probably contributed to an outbreak of multi-resistant invasive H. influenzae disease in this group
Signatures of stirring and mixing near the Gulf Stream front
In October, 1986 the surface waters adjacent to the Gulf Stream front were surveyed with an undulating profiler to describe the finescale structure of the mixed layer. The profiler was a Seasoar equipped with a CTD and fluorometer. The survey first defined the structure of a cyclonic eddy which resembled frontal eddies of the South Atlantic Bight in sea surface temperature imagery. The Seasoar transects revealed, however, that the cyclonic eddy lacked a cold dome typically seen in frontal eddies. Farther downstream the Seasoar defined the structure of streamers of Gulf Stream and Shelf water wrapped about the southern edge of a warm-core ring. The streamers had lateral and along-axis dimensions on the order of â 10 km and 100 km, respectively, and were bordered by narrow intrusive features. The temporal history of the streamers was described from SST imagery, and the surface flow derived from ship\u27s drift vectors. CTD casts taken while following an isopycnal float provided a means to examine the structure of the intrusive features. Interleaving was evident at the boundaries of the streamers and intrusive features where high conductivity Cox numbers were concentrated, suggesting elevated microstructure activity. The Turner angle distribution, indicating either saltfingering or diffusive convection, did not correlate well with the Cox number distribution. This is interpreted as evidence that lateral, rather than diapycnal, mixing was the process mediating the exchange of properties at the boundaries of contrasting water types. In contrast to physical properties, the distribution of fluorescence showed relatively less structure in the surface layer between the ring and Gulf Stream front. In the surface layers of the two streamers the pigment and bacterial biomass, and the diatom species composition, were typical of Slope water communities. We hypothesize that small-scale mixing processes concentrated at the boundaries of the streamers were the mechanism by which Slope water plankton were seeded into streamers of different hydrographic origins. Presumably, high netplankton growth rates allowed the Slope water species to dominate the communities in the streamers
Hypermatrix factors for string and membrane junctions
The adjoint representations of the Lie algebras of the classical groups
SU(n), SO(n), and Sp(n) are, respectively, tensor, antisymmetric, and symmetric
products of two vector spaces, and hence are matrix representations. We
consider the analogous products of three vector spaces and study when they
appear as summands in Lie algebra decompositions. The Z3-grading of the
exceptional Lie algebras provide such summands and provides representations of
classical groups on hypermatrices. The main natural application is a formal
study of three-junctions of strings and membranes. Generalizations are also
considered.Comment: 25 pages, 4 figures, presentation improved, minor correction
Human responses to Florida red tides : policy awareness and adherence to local fertilizer ordinances
Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Science of The Total Environment 493 (2014): 898-909, doi:10.1016/j.scitotenv.2014.06.083.To mitigate the damages of natural hazards, policy responses can be beneficial only if they are
effective. Using a self-administered survey approach, this paper focuses on the adherence to
local fertilizer ordinances (i.e., county or municipal rules regulating the application of fertilizer
to private lawns or facilities such as golf courses) implemented in jurisdictions along the
southwest Florida coast in response to hazardous blooms of Florida red tides (Karenia brevis).
These ordinances play a role in the context of evolving programs of water pollution control at
federal, state, water basin, and local levels. With respect to policy effectiveness, while the
strength of physical linkages is of critical importance, the extent to which humans affected are
aware of and adhere to the relevant rules, is equally critical. We sought to understand the
publicâs depth of understanding about the rationales for local fertilizer ordinances. Respondents
in Sarasota, Florida, were asked about their fertilizer practices in an area that has experienced
several major blooms of Florida red tides over the past two decades. A highly educated, older
population of 305 residents and âsnowbirdsâ reported relatively little knowledge about a local
fertilizer ordinance, its purpose, or whether it would change the frequency, size, or duration of
red tides. This finding held true even among subpopulations that were expected to have more
interest in or to be more knowledgeable about harmful algal blooms. In the face of uncertain
science and environmental outcomes, and with individual motivations at odds with evolving
public policies, the effectiveness of local community efforts to decrease the impacts of red tides
may be compromised. Targeted social-science research on human perceptions about the risks of
Florida red tides and education about the rationales for potential policy responses is warranted.This work was funded under sponsorship of the National Science Foundation (NSF), awards
#1009106 and #1004181and the National Institute for Environmental Health Sciences (NIEHS),
award # R21ES017413-01A2. Fleming received support from the European Regional
Development Fund and European Social Fund (European Centre for Environment and Human
Health, University of Exeter Medical School)
Religion and religious education : comparing and contrasting pupilsâ and teachersâ views in an English school
This publication builds on and develops the English findings of the qualitative study of European teenagersâ perspectives on religion and religious education (Knauth et al. 2008), part of âReligion in Education: A contribution to dialogue or a factor of conflict in transforming societies of European countries?â (REDCo) project. It uses data gathered from 27 pupils, aged 15-16, from a school in a multicultural Northern town in England and compares those findings with data gathered from ten teachers in the humanities faculty of the same school, collected during research for the Warwick REDCo Community of Practice. Comparisons are drawn between the teachersâ and their pupilsâ attitudes and values using the same structure as the European study: personal views and experiences of religion, the social dimension of religion, and religious education in school. The discussion offers an analysis of the similarities and differences in worldviews and beliefs which emerged. These include religious commitment/observance differences between the mainly Muslim-heritage pupils and their mainly non-practising Christian-heritage teachers. The research should inform the ways in which the statutory duties to promote community cohesion and equalities can be implemented in schools. It should also facilitate intercultural and interreligious understanding between teachers and the pupils from different ethnic and religious backgrounds
Dinosaur tracks from the Kilmaluag Formation (Bathonian, Middle Jurassic) of Score Bay, Isle of Skye, Scotland, UK
Tracks of a juvenile theropod dinosaur with footprint lengths of between 2 and 9 cm as well as adults of the same ichnospecies with footprints of about 15â25 cm in length were found in the Bathonian (Middle Jurassic) Kilmaluag Formation of Score Bay, northwestern Trotternish Peninsula, Isle of Skye, Scotland, UK. Two footprint sizes occur together on the same bedding plane in the central portion of Score Bay, both in situ and on loose blocks. Another horizon containing footprints above this was also identified. The footprints from the lowest horizon were produced in a desiccated silty mud that was covered with sand. A close association of both adults and juveniles with similar travel direction indicated by the footprints may suggest post-hatching care in theropod dinosaurs. Other footprints, produced on a rippled sandy substrate, have been found on the slightly higher bedding plane at this locality. Loose blocks found 130 m to the northeast in the central part of Score Bay have not been correlated with any in situ sediments, but were preserved in a similar manner to those from the higher bedding plane. These tracks represent the youngest dinosaur remains yet found in Scotland
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Temperature and territoriality in the Duke of Burgundy butterfly, Hamearis lucina
Abstract: The Duke of Burgundy butterfly (Hamearis lucina) has undergone severe declines over the last four decades. However, in recent years the UK population appears to have begun expanding again. This is likely to be due to beneficial management, although a warming regional climate may also have contributed to the resurgence of this spring-flying species. In this study, we investigated the effect of air temperature on the flight behaviour of adult male Duke of Burgundy butterflies. We also looked at the ability of adult males to behaviourally thermoregulate their body temperature and assessed their tendency to remain within small established territories. Increasing air temperature lead to a marked increase in the number and duration of flights associated with territorial behaviour but had no significant effect on other flights. This suggests that high temperatures are particularly important for sustaining energetically-demanding flights involved in territory defence and mate interception, which could impact the reproductive potential of Duke of Burgundy populations. We also found that butterflies had only a limited ability to regulate their body temperature behaviourally and may, therefore, be especially dependent on suitable environmental conditions to maintain the right temperatures for these flights. During observations, most males also remained confined to a few square meters within their territories, which could further restrict butterfly ability to thermoregulate by limiting relocation to other habitat types. However, we did find more males to leave the confines of their territories than expected from reports in previous studies. Our findings highlight the key role that warm, sheltered locations on reserves have in supporting the Duke of Burgundy. If this traditionally poor disperser is to take advantage of a warmer climate and extend its range North, a close network of such areas, appropriately managed, may be critical
Lessening the hazards of Florida red tides: a common sense approach
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Hoagland, P., Kirkpatrick, B., Jin, D., Kirkpatrick, G., Fleming, L. E., Ullmann, S. G., Beet, A., Hitchcock, G., Harrison, K. K., Li, Z. C., Garrison, B., Diaz, R. E., & Lovko, V. Lessening the hazards of Florida red tides: a common sense approach. Frontiers in Marine Science, 7, (2020): 538, doi:10.3389/fmars.2020.00538.In the Gulf of Mexico, especially along the southwest Florida coast, blooms of the dinoflagellate Karenia brevis are a coastal natural hazard. The organism produces a potent class of toxins, known as brevetoxins, which are released following cell lysis into ocean or estuarine waters or, upon aerosolization, into the atmosphere. When exposed to sufficient levels of brevetoxins, humans may suffer from respiratory, gastrointestinal, or neurological illnesses. The hazard has been exacerbated by the geometric growth of human populations, including both residents and tourists, along Floridaâs southwest coast. Impacts to marine organisms or ecosystems also may occur, such as fish kills or deaths of protected mammals, turtles, or birds. Since the occurrence of a severe Karenia brevis bloom off the southwest Florida coast three-quarters of a century ago, there has been an ongoing debate about the best way for humans to mitigate the impacts of this hazard. Because of the importance of tourism to coastal Florida, there are incentives for businesses and governments alike to obfuscate descriptions of these blooms, leading to the social amplification of risk. We argue that policies to improve the publicâs ability to understand the physical attributes of blooms, specifically risk communication policies, are to be preferred over physical, chemical, or biological controls. In particular, we argue that responses to this type of hazard must emphasize maintaining the continuity of programs of scientific research, environmental monitoring, public education, and notification. We propose a common-sense approach to risk communication, comprising a simplification of the public provision of existing sources of information to be made available on a mobile website.The research leading to these results was supported by the US National Science Foundation (NSF) under NSF Grant No. CNH 1009106. PH and DJ acknowledge the complementary support under NSF Grant No. PFI/BIC 1534054
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