Self-organized Criticality and Absorbing States: Lessons from the Ising Model

We investigate a suggested path to self-organized criticality. Originally, this path was devised to "generate criticality" in systems displaying an absorbing-state phase transition, but closer examination of the mechanism reveals that it can be used for any continuous phase transition. We used the Ising model as well as the Manna model to demonstrate how the finite-size scaling exponents depend on the tuning of driving and dissipation rates with system size.Our findings limit the explanatory power of the mechanism to non-universal critical behavior.Comment: 5 pages, 2 figures, REVTeX

Generalized (m,k)-Zipf law for fractional Brownian motion-like time series with or without effect of an additional linear trend

We have translated fractional Brownian motion (FBM) signals into a text based on two ''letters'', as if the signal fluctuations correspond to a constant stepsize random walk. We have applied the Zipf method to extract the $\zeta '$ exponent relating the word frequency and its rank on a log-log plot. We have studied the variation of the Zipf exponent(s) giving the relationship between the frequency of occurrence of words of length $m<8$ made of such two letters: $\zeta '$ is varying as a power law in terms of $m$. We have also searched how the $\zeta '$ exponent of the Zipf law is influenced by a linear trend and the resulting effect of its slope. We can distinguish finite size effects, and results depending whether the starting FBM is persistent or not, i.e. depending on the FBM Hurst exponent $H$. It seems then numerically proven that the Zipf exponent of a persistent signal is more influenced by the trend than that of an antipersistent signal. It appears that the conjectured law $\zeta ' = |2H-1|$ only holds near $H=0.5$. We have also introduced considerations based on the notion of a {\it time dependent Zipf law} along the signal.Comment: 24 pages, 12 figures; to appear in Int. J. Modern Phys

The Occurrence of Trihalomethane Compounds in Salt Lake City and Ogden, Utah, Drinking Water Supplies

A purge and trap, gas chromatography system was developed to analyze for trihalomethane (THMs) compounds at the ppb (parts per billion) level in drinking water. Monthly influent and effluent samples were taken from three Weber Basin Water Conservancy Distrcit treatment plants, three Salt Lake City water treatmetn platns, and one Slat Lake Metropolitan water treatment plant. In addition tap water samples were taken at various business and residential locations in Salt Lake City, Utah, and Ogen, Utah. All samples were analyzed for trihalomethanes and total organic carbon (TOC). In addition to monthly sampling, a comparison of the production of THMs during post and prechlorination of water at the Parleys Water Treatment Plant in Salt Lake City was conducted. moving th epoint of chlorination within the treatment plant did not appear to reudce trihalomethane levels in the finished product. Highest trihalomethane levels (84 ug/1) occurred in the summer months with the lowest levels (\u3c1 ug/1) recorded in the winter. The chemical form of the THMs varied from chloroform to the more brominated hydrocarbon from late winter through spring

Scaling in the Bombay Stock Exchange Index

In this paper we study BSE Index financial time series for fractal and multifractal behaviour. We show that Bombay stock Exchange (BSE)Index time series is mono-fractal and can be represented by a fractional Brownian motion.Comment: 11 pages,3 figure

Understanding noise stress-induced cognitive impairment in healthy adults and its implications for schizophrenia

Noise stress (NS) is detrimental to many aspects of human health and behavior. Understanding the effect of noise stressors on human cognitive function is a growing area of research and is crucial to helping clinical populations, such as those with schizophrenia, which are particularly sensitive to stressors. A review of electronic databases for studies assessing the effect of acute NS on cognitive functions in healthy adults revealed 31 relevant studies. The review revealed (1) NS exerts a clear negative effect on attention, working memory and episodic recall, and (2) personality characteristics, in particular neuroticism, and sleep influence the impact of noise stressors on performance in interaction with task complexity. Previous findings of consistent impairment in NS-relevant cognitive domains, heightened sensitivity to stressors, elevated neuroticism and sleep disturbances in schizophrenia, taken together with the findings of this review, highlight the need for empirical studies to elucidate whether NS, a common aspect of urban environments, exacerbates cognitive deficits and other symptoms in schizophrenia and related clinical populations

Unconventional carrier-mediated ferromagnetism above room temperature in ion-implanted (Ga, Mn)P:C

Ion implantation of Mn ions into hole-doped GaP has been used to induce ferromagnetic behavior above room temperature for optimized Mn concentrations near 3 at.%. The magnetism is suppressed when the Mn dose is increased or decreased away from the 3 at.% value, or when n-type GaP substrates are used. At low temperatures the saturated moment is on the order of one Bohr magneton, and the spin wave stiffness inferred from the Bloch-law T^3/2 dependence of the magnetization provides an estimate Tc = 385K of the Curie temperature that exceeds the experimental value, Tc = 270K. The presence of ferromagnetic clusters and hysteresis to temperatures of at least 330K is attributed to disorder and proximity to a metal-insulating transition.Comment: 4 pages, 4 figures (RevTex4

'If it's a medical issue I would have covered it by now': learning about fibromyalgia through the hidden curriculum: a qualitative study

BACKGROUND: Fibromyalgia syndrome (FMS) is a long-term condition that affects between 1 and 5% of the general population and lies within the spectrum of medically unexplained symptoms (MUS). FMS can be difficult to diagnose and is usually done so as a diagnosis of exclusion. There is continuing debate regarding its legitimacy excluding other causes of symptoms. It is known that the diagnosis and management of MUS, including FMS, receives little attention in medical curricula and attitudes towards patients with FMS amongst medical professionals and trainees can be negative. The purpose of this study was to investigate how attitudes and perspectives of undergraduate medical students towards FMS are acquired during their training. METHODS: Qualitative interviews with 21 medical students were conducted to explore their views on FMS, encounters with patients with FMS, and where learning about FMS occurs. Participants were recruited from two English medical schools and the study was approved by two University Ethics committees. Interviews were digitally recorded with consent and data analysed thematically, using principles of constant comparison. RESULTS: The data were organised within three themes: i) FMS is a complex, poorly understood condition; ii) multiple sources for learning about FMS; and iii) consequences of negative attitudes for patients with FMS. CONCLUSION: Undergraduate medical students have limited understanding of, and are sceptical over the existence of FMS. These attitudes are influenced by the 'hidden curriculum' and witnessing attitudes and actions of their clinical teachers. Students interpret a lack of formal curriculum teaching around FMS to mean that it is not serious and hence a low priority. Encountering a patient, friend or family member with FMS can increase knowledge and lead to altered perceptions of the condition. Teaching and learning about FMS needs to be consistent to improve knowledge and attitudes of clinicians. Undergraduate students should be exposed to patients with FMS so that they better understand patients with FMS

Light Cone Sum Rules for gamma* N -> Delta Transition Form Factors

A theoretical framework is suggested for the calculation of gamma* N -> Delta transition form factors using the light-cone sum rule approach. Leading-order sum rules are derived and compared with the existing experimental data. We find that the transition form factors in a several GeV region are dominated by the ``soft'' contributions that can be thought of as overlap integrals of the valence components of the hadron wave functions. The ``minus'' components of the quark fields contribute significantly to the result, which can be reinterpreted as large contributions of the quark orbital angular momentumComment: 38 pages, 10 figures; some typos fixed and references added, to appear in Phys. Rev.