880 research outputs found
Induced Parity Violation in Odd Dimensions
One of the interesting features about field theories in odd dimensions is the
induction of parity violating terms and well-defined {\em finite} topological
actions via quantum loops if a fermion mass term is originally present and
conversely. Aspects of this issue are illustrated for electrodynamics in 2+1
and 4+1 dimensions. (3 uuencoded Postscript Files are appended at the end of
the TexFile.)Comment: 10 pages, UTAS-PHYS-94-0
Information Cascades and the Collapse of Cooperation
In various types of structured communities newcomers choose their interaction partners by selecting a role-model and copying their social networks. Participants in these networks may be cooperators who contribute to the prosperity of the community, or cheaters who do not and simply exploit the cooperators. For newcomers it is beneficial to interact with cooperators but detrimental to interact with cheaters. However, cheaters and cooperators usually cannot be identified unambiguously and newcomersâ decisions are often based on a combination of private and public information. We use evolutionary game theory and dynamical networks to demonstrate how the specificity and sensitivity of those decisions can dramatically affect the resilience of cooperation in the community. We show that promiscuous decisions (high sensitivity, low specificity) are advantageous for cooperation when the strength of competition is weak; however, if competition is strong then the best decisions for cooperation are risk-adverse (low sensitivity, high specificity). Opportune decisions based on private and public information can still support cooperation but suffer of the presence of information cascades that damage cooperation, especially in the case of strong competition. Our research sheds light on the way the interplay of specificity and sensitivity in individual decision-making affects the resilience of cooperation in dynamical structured communities
Giant Alcohol: A Worthy Opponent for the Children of the Band of Hope
From its foundation in 1847, the temperance organisation the Band of Hope addressed its young members as consumers, victims, and agents. In the first two roles they encountered the effects of drink of necessity, but in the third role they were encouraged to seek it out, attempting to influence individuals and wider society against 'Giant Alcohol'.
With an estimated membership of half the school-age population by the early twentieth century, well over three million, the Band of Hope also acted more directly to influence policy, and encouraged young people to consider issues of policy and politics. With its wide range of activities and material to educate, entertain and empower millions of children, and its radical view of the place of the child, the Band of Hope not only mobilised its child members to lobby for legal change, including prohibition, but took an active part in pointing out the cost of alcohol to society, particularly during the 14-18 war. The organisation began to decline post 1918, and this paper focuses on the address made to children by the Band of Hope in the late nineteenth and early twentieth centuries, at a time when its innovative view of children as able to understand and influence policy decisions reflected developments in the construction of childhood. This article draws on the archive of the British National Temperance League, over 50,000 items located in the Livesey Collection, University of Central Lancashire
Emergence of structure in mouse embryos : structural entropy morphometry applied to digital models of embryonic anatomy
We apply an information-theoretic measure to anatomical models of the Edinburgh Mouse Atlas Project. Our goal is to quantify the anatomical complexity of the embryo and to understand how this quantity changes as the organism develops through time. Our measure, Structural Entropy, takes into account the geometrical character of the intermingling of tissue types in the embryo. It does this by a mathematical process that effectively imagines a point-like explorer that starts at an arbitrary place in the 3D structure of the embryo and takes a random path through the embryo, recording the sequence of tissues through which it passes. Consideration of a large number of such paths yields a probability distribution of paths making connections between specific tissue types, and Structural Entropy is calculated from this (mathematical details are given in the main text). We find that Structural Entropy generally decreases (order increases) almost linearly throughout developmental time (4â18Â days). There is one `blipâ of increased Structural Entropy across days 7â8: this corresponds to gastrulation. Our results highlight the potential for mathematical techniques to provide insight into the development of anatomical structure, and also the need for further sources of accurate 3D anatomical data to support analyses of this kind
Contemporary France
First published in 1984. Routledge is an imprint of Taylor & Francis, an informa company
Detection of Mycoplasma pneumoniae in Simulated and True Clinical Throat Swab Specimens by Nanorod Array-Surface-Enhanced Raman Spectroscopy
The prokaryote Mycoplasma pneumoniae is a major cause of respiratory disease in humans, accounting for 20% of all community-acquired pneumonia and the leading cause of pneumonia in older children and young adults. The limitations of existing options for mycoplasma diagnosis highlight a critical need for a new detection platform with high sensitivity, specificity, and expediency. Here we evaluated silver nanorod arrays (NA) as a biosensing platform for detection and differentiation of M. pneumoniae in culture and in spiked and true clinical throat swab samples by surface-enhanced Raman spectroscopy (SERS). Three M. pneumoniae strains were reproducibly differentiated by NA-SERS with 95%â100% specificity and 94â100% sensitivity, and with a lower detection limit exceeding standard PCR. Analysis of throat swab samples spiked with M. pneumoniae yielded detection in a complex, clinically relevant background with >90% accuracy and high sensitivity. In addition, NA-SERS correctly classified with >97% accuracy, ten true clinical throat swab samples previously established by real-time PCR and culture to be positive or negative for M. pneumoniae. Our findings suggest that the unique biochemical specificity of Raman spectroscopy, combined with reproducible spectral enhancement by silver NA, holds great promise as a superior platform for rapid and sensitive detection and identification of M. pneumoniae, with potential for point-of-care application
Landau-Khalatnikov-Fradkin Transformations and the Fermion Propagator in Quantum Electrodynamics
We study the gauge covariance of the massive fermion propagator in three as
well as four dimensional Quantum Electrodynamics (QED). Starting from its value
at the lowest order in perturbation theory, we evaluate a non-perturbative
expression for it by means of its Landau-Khalatnikov-Fradkin (LKF)
transformation. We compare the perturbative expansion of our findings with the
known one loop results and observe perfect agreement upto a gauge parameter
independent term, a difference permitted by the structure of the LKF
transformations.Comment: 9 pages, no figures, uses revte
Macrolideâresistant Mycoplasma pneumoniae pneumonia in transplantation: Increasingly typical?
Mycoplasma pneumoniae is one of the most common bacterial causes of pneumonia. Macrolideâresistant MÂ pneumoniae (MRMP) was documented in 7.5% of isolates in the United States. Resistance portends poor outcomes to macrolide therapy, yet patients respond well to fluoroquinolones or tetracyclines such as minocycline. However, MRMP may be underâappreciated because MÂ pneumoniae generally causes relatively mild infections in nonâimmunosuppressed adults that may resolve without effective therapy and because microbiological confirmation and susceptibility are not routinely performed. We report two cases of pneumonia due to MRMP in kidney transplant recipients. Both patients required hospital admission, worsened on macrolide therapy, and rapidly defervesced on doxycycline or levofloxacin. In one case, MÂ pneumoniae was only identified by multiplex respiratory pathogen panel analysis of BAL fluid. Macrolide resistance was confirmed in both cases by realâtime PCR and point mutations associated with macrolide resistance were identified. MÂ pneumoniae was isolated from both cases, and molecular genotyping revealed the same genotype. In conclusion, clinicians should be aware of the potential for macrolide resistance in MÂ pneumoniae, and may consider nonâmacrolideâbased therapy for confirmed or nonâresponding infections in patients who are immunocompromised or hospitalized.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163484/2/tid13318.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163484/1/tid13318_am.pd
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