Dual Monte Carlo and Cluster Algorithms

We discuss the development of cluster algorithms from the viewpoint of probability theory and not from the usual viewpoint of a particular model. By using the perspective of probability theory, we detail the nature of a cluster algorithm, make explicit the assumptions embodied in all clusters of which we are aware, and define the construction of free cluster algorithms. We also illustrate these procedures by rederiving the Swendsen-Wang algorithm, presenting the details of the loop algorithm for a worldline simulation of a quantum $S=$ 1/2 model, and proposing a free cluster version of the Swendsen-Wang replica method for the random Ising model. How the principle of maximum entropy might be used to aid the construction of cluster algorithms is also discussed.Comment: 25 pages, 4 figures, to appear in Phys.Rev.

Adoption of Goat Production Technology and Its Impact Among Rural Farmers in Nawalparsi District of Nepal

Nayabelhani VDC of Nawalparasi district was chosen to judge the effectiveness of goat production technology supported by Heifer International Nepal. Field survey with before and after approach was employed in the study. Information obtained from Stratified random sampling technique from 90 households with structured questionnaire and was compared with the baseline data. Adoption index was calculated through scoring technique after content validation. Participatory rural appraisal for problems identification. The research revealed that the extent of adoption of scientific goat production technology after project was higher than before project (80% Vs 32%, P<0.01). Further, the average herd size after the project was slightly decreased from 6.585 to 5.677 while the kid mortality dropped from 15% to 11%. The average number of kidding in 2 years was increased from 2 to 3 and the average number of kids per kidding was increased from 1 to 2. Goats were more frequently marketed at an average age of 12 months with an average weight of 24kg after the project. Similarly, the average annual income from the goat per household was found to be almost doubled from Nrs. 8,489 to Nrs. 15,084. Predator was found to be the most serious problem out of seven identified problems

The Prevalence and Reasons for Interruption of Antituberculosis Treatment by Patients at Mbekweni Health Centre in King Sabata Dalidyebo (KSD) District in the Eastern Cape Province

Background: In spite of effective therapy, tuberculosis (TB) is still a major health problem in developing countries. In 1993, therefore, the World Health Organization declared TB a global emergency. In South Africa, TB is one of the most prevalent diseases, with an incidence of 556 per 100 000 population. In spite of free TB drugs in the public service and the directly observed treatment short course (DOTS) strategies, there is still a high prevalence of TB and a high treatment interruption rate in rural South Africa. Methods: The objectives of this study were to establish the prevalence of TB and reasons for the interruption of TB treatment by patients attending Mbekweni Health Centre in King Sabata Dalidyebo (KSD) district in the Eastern Cape province. This was a cross- sectional study in which data were collected from 15 July 2004 to 15 January 2005 from patients who were on TB treatment and interrupted their treatment between 6 August 2001 and 30 December 2003. Results: Of the 255 TB patients who attended for treatment, 121 (47.5%) had interrupted their treatment. Reasons given for interrup- tion included change of living place (18.96%), no money to go to the clinic (15.52%), feeling better (13.78%), side effects of the drug (6.90%), did not know the treatment course (5.17%), physical disability either old or too sick to collect treatment and nobody to help (5.17%), clinic too far (1.73%), drug not available in the clinic (13.83%) and no reasons (8.62%). Conclusion: The prevalence of treatment interruption was high in this study. Change of living place, lack of money for visiting the clinic to collect treatment, feeling better, and no drugs at the clinic were the major reasons given for interruption of treatment. Ensuring the availability of TB drugs at the health centre/clinic, patient education about TB and strengthening the DOTS programme, including a stipend for the DOTS supervisors, would help to reduce the prevalence of treatment interruption. South African Family Practice Vol. 50 (6) 2008: pp. 47-47

On generalized cluster algorithms for frustrated spin models

Standard Monte Carlo cluster algorithms have proven to be very effective for many different spin models, however they fail for frustrated spin systems. Recently a generalized cluster algorithm was introduced that works extremely well for the fully frustrated Ising model on a square lattice, by placing bonds between sites based on information from plaquettes rather than links of the lattice. Here we study some properties of this algorithm and some variants of it. We introduce a practical methodology for constructing a generalized cluster algorithm for a given spin model, and investigate apply this method to some other frustrated Ising models. We find that such algorithms work well for simple fully frustrated Ising models in two dimensions, but appear to work poorly or not at all for more complex models such as spin glasses.Comment: 34 pages in RevTeX. No figures included. A compressed postscript file for the paper with figures can be obtained via anonymous ftp to minerva.npac.syr.edu in users/paulc/papers/SCCS-527.ps.Z. Syracuse University NPAC technical report SCCS-52

Loop Algorithms for Asymmetric Hamiltonians

Generalized rules for building and flipping clusters in the quantum Monte Carlo loop algorithm are presented for the XXZ-model in a uniform magnetic field along the Z-axis. As is demonstrated for the Heisenberg antiferromagnet it is possible from these rules to select a new algorithm which performs significantly better than the standard loop algorithm in strong magnetic fields at low temperatures.Comment: Replaced measurement of helicity modulus at H=2J with a measurement at H=3.95J + other small changes in the section on numerical result

Coarse-grained loop algorithms for Monte Carlo simulation of quantum spin systems

Recently, Syljuasen and Sandvik proposed a new framework for constructing algorithms of quantum Monte Carlo simulation. While it includes new classes of powerful algorithms, it is not straightforward to find an efficient algorithm for a given model. Based on their framework, we propose an algorithm that is a natural extension of the conventional loop algorithm with the split-spin representation. A complete table of the vertex density and the worm-scattering probability is presented for the general XXZ model of an arbitrary S with a uniform magnetic field.Comment: 12 pages, 7 figures, insert a word "squared" in the first line of the caption of Fig.7 and correct the label of vertical axis of Fig.

Magic Islands and Barriers to Attachment: A Si/Si(111)7x7 Growth Model

Surface reconstructions can drastically modify growth kinetics during initial stages of epitaxial growth as well as during the process of surface equilibration after termination of growth. We investigate the effect of activation barriers hindering attachment of material to existing islands on the density and size distribution of islands in a model of homoepitaxial growth on Si(111)7x7 reconstructed surface. An unusual distribution of island sizes peaked around "magic" sizes and a steep dependence of the island density on the growth rate are observed. "Magic" islands (of a different shape as compared to those obtained during growth) are observed also during surface equilibration.Comment: 4 pages including 5 figures, REVTeX, submitted to Physical Review

Quality of Life and Persons With Intellectual Disability: Can We Measure QOL in This Population?

Quality of life (QOL) has been discussed by professionals working with persons with intellectual disability (ID) for some time, but since QOL is concerned with subjective well-being, satisfaction and happiness, how is it possible to measure, when the person in question is unable to communicate? Consciousness is believed to be an internal and personal thing, but we have done the simple experiment to ask observers to rate QOL of another person, also in sub dimensions like self-assessed physical and mental health, relationship with self, self-assessed sexual ability, self-assessed social ability, and we have found that people are able to assess the QOL rather accurate of other people. The fact that we are fairly able to read other person‘s mind and tell their state of consciousness, quality of life and quality of relationships indicate that we are able to share consciousness as an objective phenomenon. As a practical consequence we can measure QOL of people who are unable to communicate allowing us to improve care and make better decisions about life and death. We recommend observer-rated QOL1/QOL5/QOL10 for quality assurance of the medical, psychological or CAM/holistic therapeutic treatments of all patients groups that for some reason, i.e. ID, coma, psychosis, and brain damage has no sufficient language, intelligence, self-insight or ability to rate themselves. We find that the Personal-Development-Q5 (PD5) questionnaire measuring the level of personal developmental in five dimensions: emotions, mind, sexuality, spirituality and I-strength, can also be observer-rated. A strategy for measuring QOL in persons with intelligence deficits (ID) is presented