38,809 research outputs found
Social networking in a disconnected network: fbDTN: facebook over DTN
In this demo, we describe the design and implementation of fbDTN, a gateway that allow users to access Facebook services over a Disruption Tolerant Network (DTN) in a convenient and secure manner. Our system enables users to read their news feed, post status updates and photos, and comment and "like" the posts of other people. We also show the importance of supporting applications like this in a DTN and allow demo session attendees to see this system in action
Towards new methods for mobility data gathering: content, sources, incentives
Over the past decade, huge amounts of work has been done in mobile and opportunistic networking research. Unfortunately, much of this has had little impact as the results have not been applicable to reality, due to incorrect assumptions and models used in the design and evaluation of the systems.
In this paper, we outline some of the problems of the assumptions of early research in the field, and provide a survey of some initial work that has started to take place to alleviate this through more realistic modelling and measurements of real systems. We do note that there is still much work to be done in this area, and then go on to identify some important properties of the network that must be studied further. We identify the types of data that are important to measure, and also give some guidelines on finding existing and potentially new sources for such data and incentivizing the holders of the data to share it
Dementia and Primary-Care Health Measures:Hearing, Gait, and Markers of Inflammation
Dementia is a syndrome associated with declining cognitive function that has a variety of types and causes, and is encountered frequently in general medical practice. Researchers are actively exploring possible risk factors for dementia. The St. Louis University Mental Status (SLUMS) exam is a dementia-screening exam used in primary care visits to detect cognitive impairment that may be a sign of dementia. This study compared scores on the SLUMS exam to other measures recorded in a typical primary care visit in 86 patients of age 65 and older to look for correlations between indicators of health, such as physical examination measures and complete blood count panels, and cognitive impairment, as measured by score on the SLUMS exam. Abnormal gait was associated with a lower score on the SLUMS exam compared to normal (p=.006), failure of the hearing test in both ears was associated with a lower score on the SLUMS exam compared to patients passing the hearing test in one or both ears (p=.046), red blood cell count was positively correlated with SLUMS exam score (p=.020), white blood cell count was negatively correlated with SLUMS exam score (p=.003), and serum albumin levels were negatively correlated with SLUMS exam score (p=.002). These data support the view that both physical impairments and markers of an inflammatory response are related to dementia
Black hole formation from point-like particles in three-dimensional anti-de Sitter space
We study collisions of many point-like particles in three-dimensional anti-de
Sitter space, generalizing the known result with two particles. We show how to
construct exact solutions corresponding to the formation of either a black hole
or a conical singularity from the collision of an arbitrary number of massless
particles falling in radially from the boundary. We find that when going away
from the case of equal energies and discrete rotational symmetry, this is not a
trivial generalization of the two-particle case, but requires that the excised
wedges corresponding to the particles must be chosen in a very precise way for
a consistent solution. We also explicitly take the limit when the number of
particles goes to infinity and obtain thin shell solutions that in general
break rotational invariance, corresponding to an instantaneous and
inhomogeneous perturbation at the boundary. We also compute the stress-energy
tensor of the shell using the junction formalism for null shells and obtain
agreement with the point particle picture.Comment: 42 pages, 9 figures; v2: fixed some typo
A statistical analysis of Electromagnetic Ion Cyclotron (EMIC) waves and their correlation to the 11-year solar cycle
This thesis presents a statistical analysis of EMIC waves measured at Halley Research Station from 2008 through 2012. An introduction covering the origin of and theory behind EMIC waves is provided, along with a background covering previous statistical research regarding EMIC waves. Guidelines regarding EMIC wave definition and analysis are described along with examples of how they were used. The data shows an increase in the total number of EMIC waves as well as the number and percentage of EMIC waves with maximum frequency above 1 Hz during the 5-year period. The results suggest that the total number of EMIC waves and the proportion of EMIC waves with maximum frequency above 1 Hz increase with increasing solar activity. A future perspective in EMIC wave research is also provided
Inexpensive insulation is effective for cryogenic transfer lines
Matting cover thermally insulates cryogenic-liquid transfer pipelines. The matting consists of layers of commercially available fiber glass tape in which the fibers are randomly oriented in parallel planes
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