From exotic phases to microscopic Hamiltonians

We report recent analytical progress in the quest for spin models realising exotic phases. We focus on the question of `reverse-engineering' a local, SU(2) invariant S=1/2 Hamiltonian to exhibit phases predicted on the basis of effective models, such as large-N or quantum dimer models. This aim is to provide a point-of-principle demonstration of the possibility of constructing such microscopic lattice Hamiltonians, as well as to complement and guide numerical (and experimental) approaches to the same question. In particular, we demonstrate how to utilise peturbed Klein Hamiltonians to generate effective quantum dimer models. These models use local multi-spin interactions and, to obtain a controlled theory, a decoration procedure involving the insertion of Majumdar-Ghosh chainlets on the bonds of the lattice. The phases we thus realise include deconfined resonating valence bond liquids, a devil's staircase of interleaved phases which exhibits Cantor deconfinement, as well as a three-dimensional U(1) liquid phase exhibiting photonic excitations.Comment: Invited talk at Peyresq Workshop on "Effective models for low-dimensional strongly correlated systems". Proceedings to be published by AIP. v2: references adde

MTHFR A1298C polymorphism and idiopathic male infertility

Background: DNA methylation is an important epigenetic feature of DNA that plays a pivotal role in gene expression regulation during spermatogenesis. The enzyme methylenetetrahydrofolate reductase (MTHFR) catalyses the formation of folate intermediates that are vital for DNA synthesis and methylation reactions. C677T and A1298C variants of MTHFR result in reduced plasma folate and increase the susceptibility to various multifactorial disorders. We have already shown that homozygosity for 677 (C ®T) mutation in the MTHFR gene, is a risk factor for idiopathic male infertility in an Indian population. Aim: Recently, we showed that homozygosity for the 677(C;T) mutation in the MTHFR gene is a risk factor for idiopathic male infertility and now we aim to assess whether the A1298C mutation in the same gene is an additional risk factor for idiopathic male infertility in an Indian population. Setting and Designs : In a case-control study 151 idiopathic male infertile patients and 140 healthy fertile control individuals were recruited from the University hospital and infertility clinics in Varanasi city, India. Materials and Methods: Genotyping for A1298C change of the MTHFR gene was done by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Statistical Analysis : Allele frequencies were calculated using Fisher's exact test. Odds ratio was calculated as the measure of the association between the MTHFR genotype and idiopathic male infertility. Results : The homozygous (C/C) A1298C polymorphism of the MTHFR gene was present at a statistically high significance in idiopathic azoospermic infertile men (OR=3.4494, CI: 1.0092 to 11.7899, P<0.05). Conclusion : The MTHFR 1298CC genotype is an additional genetic risk factor for idiopathic male infertility in an Indian population

A PROCESS STUDY OF EFFECTS OF GSS AND TASK TYPE ON INFORMATIONAL AND NORMATIVE INFLUENCE IN SMALL GROUPS

This research examines the effects of GSS and task type on informational and normative influence in small groups by analyzing group process. It extends Kaplan and Miller\u27 s research on task type and informational and normative influence in small groups in an unsupported setting to a GSS setting. The two tasks used are an intellective task and a preference task, and the two support levels are unsupported baseline and GSS support. The findings show that (1) the mode of influence that predominates in group discussion depends on task type, but the degree of dominance is moderated by support level, and (2) GSS has the potential to encourage the use of informational influence in intellective task groups and discourage the use of normative influence in preference task groups. These findings suggest that task type may have significant effects on influence behavior in small groups and a GSS may have some beneficial effects for certain task types but not for others. The paper concludes with some suggestions for further research

On the diffraction of light by spherical obstacles

The diffraction of light inside the shadow, thrown by a small source of light, of a sphere and a circular disc of the same diameter, was studied, with special reference to the relative intensities of the central bright spots. With the source at about 2 metres from the obstacles, with a quarter-inch polished steel ball, the bright spot could be detected visually up to 3 cm. behind the obstacle, while with a steel disc of the same diameter, with the edges perfectly sharp, smooth and circular, the spot could be traced up to 2 cm. The relative intensities of the two spots were studied at different distances behind the obstacles, qualitatively by photography and quantitatively by visual photometry. At small distances behind the obstacles, the spot inside the shadow of the sphere is much feebler than the disc-spot, however approximating to the latter as we reach farther back from the obstacles, but even at 100 cm. remaining appreciably feebler. A general explanation is suggested

Acute Burkitt\u27s Leukemia: Case Report and Literature Review

The occurrence of leukemia in Burkitt\u27s lymphoma, with or without visceral or nodal tumefaction is uncommon, and its initial presentation as leukemia is even more unusual. Because it has a poor chemotherapeutic response and a grave prognosis, it is important to recognize this unusual leukemia correctly. Our report describes the clinical and pathologic findings of Burkitt\u27s lymphoma cell leukemia in a five-year-old white boy who presented with abdominal distension, hepatosplenomegaly, and lymphadenopathy. Blood examination revealed normocytic normochromic anemia, erythroblastosis, slight leukocytosis, and the presence of numerous (24%) blasts. A diagnosis of Burkitt\u27s lymphoma was established on the basis of morphologic, cytochemical, and immunologic studies performed on the blasts. When the chemotherapy protocol for the lymphoma was administered, the patient responded well initially but suffered uric acid nephropathy, which was successfully treated. However, within two weeks he had a rapid relapse of leukemia and died four months after admission

An Exploratory Case Study on IS Implementation and Organizational Change in China

Owing to the turbulent and fast changing environment in which Chinese firms operate, Information Systems (IS) implementation triggers important organizational changes in these firms. Starting with the premise that both the depth and nature of such changes are markedly different from what firms experience in other economies, this paper makes an attempt in conceptualizing issues relating to IS implementation in the Chinese context. It addresses critical success factors, expounds on the processes involved, and deals with the criteria for assessing a firm’s success or failure. A case study was conducted which entailed the examination of two key applications, financial accounting and personnel administration. This initial exploration indicates relevance of certain factors in the existing literature, and brings to light the potentiality of several factors pertinent to the current state of the Chinese business environment, which is heavily influenced by the cultural and economic backgrounds of this huge country. The study is the beginning part of a larger research program, which aims to include multiple cases in different but major industries. The findings enrich the literature on IS implementation by offering some new dimensions of understanding