3,690 research outputs found
A theoretical analysis of the current-voltage characteristics of solar cells
The current-voltage characteristics and efficiencies of solar cells are discussed. For one solar cell structure detailed curves are presented which include carrier densities, current densities, potential, and quasi-Fermi levels at different voltage levels both with and without optically generated carriers (AMO conditions). In addition some results are presented concerning the influence of various parameter variations such as lifetime, cell thickness, and high-low junction width on solar cell performance
Gossip on Weighted Networks
We investigate how suitable a weighted network is for gossip spreading. The
proposed model is based on the gossip spreading model introduced by Lind et.al.
on unweighted networks. Weight represents "friendship." Potential spreader
prefers not to spread if the victim of gossip is a "close friend". Gossip
spreading is related to the triangles and cascades of triangles. It gives more
insight about the structure of a network.
We analyze gossip spreading on real weighted networks of human interactions.
6 co-occurrence and 7 social pattern networks are investigated. Gossip
propagation is found to be a good parameter to distinguish co-occurrence and
social pattern networks. As a comparison some miscellaneous networks and
computer generated networks based on ER, BA, WS models are also investigated.
They are found to be quite different than the human interaction networks.Comment: 8 pages, 4 figures, 1 tabl
Checks and cheques : implementing a population health and recall system to improve coverage of patients with diabetes in a rural general practice
Identification of all diabetic patients in the population is essential if diabetic care is to be effective in achieving the targets of the St Vincent Declaration.1 The challenge therefore is to establish population based monitoring and control systems by means of state of the art technology in order to achieve quality assurance in the provision of care for patients with diabetes. 2,3 Disease management receives extensive international support as the most appropriate approach to organising and delivering healthcare for chronic conditions like diabetes.4 This approach is achieved through a combination of guidelines for practice, patient education, consultations and follow up using a planned team approach and a strong focus on continuous quality improvement using information technology. 5,6 The current software (Medical Director) could not easily meet these requirements which led us to adopt a trial of Ferret. In designing this project we used change management7 and the plan, do, study, act cycle8 illustrated in Diagram 1.<br /
Scaffold searching: automated identification of similar ring systems for the design of combinatorial libraries
Rigid ring systems can be used to position receptor-binding functional groups in 3D space and they thus play an increasingly important role in the design of combinatorial libraries. This paper discusses the use of shape-similarity methods to identify ring systems that are structurally similar to, and aligned with, a user-defined target ring system. These systems can be used as alternative scaffolds for the construction of a combinatorial library
Evolution of Ego-networks in Social Media with Link Recommendations
Ego-networks are fundamental structures in social graphs, yet the process of
their evolution is still widely unexplored. In an online context, a key
question is how link recommender systems may skew the growth of these networks,
possibly restraining diversity. To shed light on this matter, we analyze the
complete temporal evolution of 170M ego-networks extracted from Flickr and
Tumblr, comparing links that are created spontaneously with those that have
been algorithmically recommended. We find that the evolution of ego-networks is
bursty, community-driven, and characterized by subsequent phases of explosive
diameter increase, slight shrinking, and stabilization. Recommendations favor
popular and well-connected nodes, limiting the diameter expansion. With a
matching experiment aimed at detecting causal relationships from observational
data, we find that the bias introduced by the recommendations fosters global
diversity in the process of neighbor selection. Last, with two link prediction
experiments, we show how insights from our analysis can be used to improve the
effectiveness of social recommender systems.Comment: Proceedings of the 10th ACM International Conference on Web Search
and Data Mining (WSDM 2017), Cambridge, UK. 10 pages, 16 figures, 1 tabl
Close relationships: A study of mobile communication records
Mobile phone communication as digital service generates ever-increasing
datasets of human communication actions, which in turn allow us to investigate
the structure and evolution of social interactions and their networks. These
datasets can be used to study the structuring of such egocentric networks with
respect to the strength of the relationships by assuming direct dependence of
the communication intensity on the strength of the social tie. Recently we have
discovered that there are significant differences between the first and further
"best friends" from the point of view of age and gender preferences. Here we
introduce a control parameter based on the statistics of
communication with the first and second "best friend" and use it to filter the
data. We find that when is decreased the identification of the
"best friend" becomes less ambiguous and the earlier observed effects get
stronger, thus corroborating them.Comment: 11 pages, 7 figure
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Remarkable dynamics of nanoparticles in the urban atmosphere
Nanoparticles emitted from road traffic are the largest source of respiratory exposure for the general public living in urban areas. It has been suggested that the adverse health effects of airborne particles may scale with the airborne particle number, which if correct, focuses attention on the nanoparticle (less than 100 nm) size range which dominates the number count in urban areas. Urban measurements of particle size distributions have tended to show a broadly similar pattern dominated by a mode centred on 20–30 nm diameter particles emitted by diesel engine exhaust. In this paper we report the results of measurements of particle number concentration and size distribution made in a major London park as well as on the BT Tower, 160 m high. These measurements taken during the REPARTEE project (Regents Park and BT Tower experiment) show a remarkable shift in particle size distributions with major losses of the smallest particle class as particles are advected away from the traffic source. In the Park, the traffic related mode at 20–30 nm diameter is much reduced with a new mode at <10 nm. Size distribution measurements also revealed higher number concentrations of sub-50 nm particles at the BT Tower during days affected by higher turbulence as determined by Doppler Lidar measurements and indicate a loss of nanoparticles from air aged during less turbulent conditions. These results suggest that nanoparticles are lost by evaporation, rather than coagulation processes. The results have major implications for understanding the impacts of traffic-generated particulate matter on human health
The No-Triangle Hypothesis for N=8 Supergravity
We study the perturbative expansion of N=8 supergravity in four dimensions
from the viewpoint of the ``no-triangle'' hypothesis, which states that
one-loop graviton amplitudes in N=8 supergravity only contain scalar box
integral functions. Our computations constitute a direct proof at six-points
and support the no-triangle conjecture for seven-point amplitudes and beyond.Comment: 43page
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