Two quantum spin models on the checkerboard lattice with an exact two-fold degenerate Shastry-Sutherland ground state

Two quantum spin models with bilinear-biquadratic exchange interactions are constructed on the checkerboard lattice. It is proved that, under certain sufficient conditions on the exchange parameters, their ground states consist of two degenerate Shastry-Sutherland singlet configurations. The constructions are studied for arbitrary spin-S. The sufficient conditions for the existence of ferromagnetic ground state are also found exactly. The approximate quantum phase diagrams are presented using the exact results, together with a variational estimate for the N\'eel antiferromagnetic phase. A two-leg spin-1/2 ladder model, based on one of the above constructions, is considered which admits exact solution for a large number of eigenstates. The ladder model is shown to have exact level-crossing between the rung-singlet state and the AKLT state in the singlet ground state. Also introduced is the notion of perpendicularity for quantum spin vectors, which appears in the discussion on one of the two checkerboard models, and is discussed in the Appendix.Comment: Revtex, 10 pages, 6 figures, 3 table

On the highly reddened members in 6 young galactic star clusters - a multiwavelength study

The spectral and reddening properties of 211 highly reddened proper motion members with $V < 15$ mag in 6 young galactic star clusters are investigated using low resolution spectroscopic, broad-band $UBVRIJHK$ and mid-IR data. We report emission features in CaII HK and HI lines for a sample of 29 stars including 11 stars reported for the first time and also provide either a new or more reliable spectral class for a sample of 24 stars. CaII triplet width measurements are used to indicate the presence of an accretion disk for a dozen stars and to hint luminosity for a couple of stars. On the basis of spectral features, near-IR excesses, dereddened color-color diagrams and mid-IR spectral indices we identify a group of 28 pre-main sequence cluster members including 5 highly probable Herbig Ae/Be and 6 classical T Tauri star. A total of 25 non-emission MS stars, amounting to $\sim$ 10 % early type MS members, appears to show Vega-like characteristics or are precursors to such a phenomenon. The various membership indicators suggest that $\sim$ 16% of the PM members are non-members. A significant fraction ($>$70%) of program stars in NGC 1976, NGC 2244, NGC 6530 and NGC 6611 show anomalous reddening with $R_{V}$ = $5.11\pm0.11$, $3.60\pm0.05$, $3.87\pm0.05$ and $3.56\pm 0.02$, respectively, indicating the presence of grain size dust larger than that typical to the diffuse medium. A small number of stars in NGC 1976, NGC 2244 and NGC 6611 also show normal behavior while the cluster NGC 6823 appears to have a normal reddening. Three highly luminous late type giants, one in NGC 2244 and two in NGC 6530, appears to be member and are in post-hydrogen-core-burning stages suggesting a prolonged duration ($\sim$ 25 Myrs) of star formation.Comment: 12 pages, 13 figures, submitted to MNRA

Experimental evaluation of anti-hyperglycemic and hypolipidemic effects of stevia rebaudiana, Anacardium occidentale on wistar rats

Background: Diabetes mellitus, obesity, hypertension, hyperlipidaemia etc. is one of the pandemic metabolic disorder in the world, may lead to obesity, hypertension, hyperlipidaemia etc. Despite of medical advances like oral hypoglycemic agents, insulin pump, xenotransplantation and all don't provide enough control of blood sugar level to control Diabetes and its complications. Hence it is the right time for work on a new medicine, which can successfully control the blood sugar and bodily lipids and cost effective one also. In the present study an attempt is made to check the efficacy of folklore drugs with a conventional anti-diabetic compound glibenclamide.Methods: The decoction of a drugs Stevia rebaudiana and Anacardium occidentale prepared as described in The Ayurvedic Formulary of India, wistar rats of either sex were selected randomly. Before and after values of blood glucose, triglyceride, high density lipid and total cholesterol level were taken.Results: On analyzing the results, the study showed that the trial drug II stevia is effective and trial drug I Kajutaka is slightly effective in reducing the glucose level next to glibenclamide. The trial drug I Kajutaka showed effective in reducing the Triglyceride level followed by Stevia. The action may be due to alkaloids such as Stevioside, Rebaudioside possessed by Stevia, which may stimulate the islets of the pancreas to release Insulin. The Hypolipedimic action may be due to presence of Chemical constituents in Kajutaka leaf such as Ascorbic acid and Niacin.Conclusions: The present experimental study is preliminary one elaborate study with larger sample size is required to come up with a more significant result

Emergent Radiation in an Atom-Field System at Twice-Resonance

A two-level atom interacting with a single mode of quantized electromagnetic radiation is discussed using a representation in which the atom and the radiation are unified into a {\em new} canonical radiation. At the {\em twice-resonance}, when the frequency of the original radiation is twice the atomic transition frequency ($\omega=2\epsilon$), the {\em emergent} unified field in the non-interacting atom-field system resembles a free radiation of frequency $\epsilon$. This free emergent radiation is further shown to exist in the presence of an interaction which looks similar to the atom-field interaction in the dipole approximation. The one-photon correlation and the population inversion are discussed as the possible means of observing the emergent radiation. The entanglement properties of the emergent radiation are also discussed.Comment: 4+ pages, 2 figures, submitted for publication; included a discussion on the entanglemen

A Review on Toxic Drug – Gunja

The Visha Dravya Gunja is mentioned in Samhita and other Ayurvedic texts. In Samhita it is mentioned under Sthavara Visha and in the texts of Rasashastra it classified is under Upavishas. The history of poisons and poisoning dates back several thousand years. Abrus precatorius is a severely invasive plant in warm temperate to tropical regions, so much so that it has become effectively pantropical in distribution. It has been estimated that some form of poison directly or indirectly is responsible for more than 1 million illnesses worldwide annually. Most cases of poisoning actually go unreported, especially in Third world countries. The incidence of poisoning in India is highest in the world. The causes of poisoning in India are highest in the world. The commonest agents in India appear to be plant toxins, pesticides, chemical and household poisons. The Shodhana of Gunja is also mentioned in Ayurvedic texts. In this manuscript the detail explanation regarding Gunja in Ayurvedic and contemporary texts has been compiled and critically analyzed

A 2D quantum antiferromagnet with a four-fold degenerate valence-bond-solid ground state

We study the competition between antiferromagnetic order and valence bond solid formation in a two-dimensional frustrated spin-1/2 model. The J1-J2 model on the square lattice is further frustrated by introducing products of three-spin projectors which stabilize four dimer-product states as degenerate ground states. These four states are reminiscent of the dimerized singlet ground state of the Shastry-Sutherland model. Using exact diagonalizations, we study the evolution of the ground state by varying theratio of interactions. For a large range of parameters (J2 > 0.25J1), our model shows a direct transition between the valence-bond-solid phase and the collinear antiferromagnetic phase. For small values of J2, several intermediate phases appear which are also analyzed

Concept of Shatkriyakala as mentioned in Sushruta Samhita

Ayurveda, our cultural heritage, is the ancient system of medicine, serving living beings since time immemorial. It is a unique system, in the sense of its fundamental doctrines and concepts. Kriyakala is one of the various important concepts described in Ayurveda treatises. Kriyakala means opportunity or time to administer treatment. These are six in number and are hence known as Shatkriyakala viz. sanchaya, prakopa, prasara, sthansamshraya, vyakti and bheda. It is a concept which describes different phases of a disease in its own unique way. It shows the step wise progress of dosha and disease. Kriyakala is helpful in the diagnosis, prognosis and the treatment of a disease. This very concept is useful even in prevention of diseases

MAPPING OF SITTAMPUNDI ANORTHOSITE COMPLEX (SAC) IN SOUTHERN GRANULITE TERRAIN (SGT), INDIA WITH ASTER AND SENTINEL-2A DATA

The Sittampundi Anorthosite Complex (SAC) is a well-exposed Archean layered anorthosite-gabbro- ultramafic rock complex in southern India. SAC well preserved white- and dark-anorthosite,gabbros, and ultramafic rocks. This study aims to discriminate, characterize, and separate from adjacent and surrounding rocks the anorthosite complex in sitampundi using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Sentinel-2A data. Methods such as band color composites (True color composite, False color composite and Pseudo color composite), Principal Component Analysis (PCA), Minimum Noise Fraction (MNF) and Spectral Angle Mapper (SAM), are applied to discriminate the anorthosite complex in SGT (Southern Granulite Terrain). Band composites enhance the litho units using visible and shortwave infrared bands and thus, assisted in mapping for the anorthosite complex. PCA and MNF have been applied to the ASTER and Sentinel- 2A bands in order to decrease the redundant information in highly correlated bands. PCA and MNF driven band combinations facilitate the validation and help in discriminating the various lithological units exposed in the study area. SAM classifier classification technique was utilized to characterize the selected surface mineral assemblages from Sitampundi Anorthosite Complex using spectral signatures. The above- mentioned digital image processing techniques have been proven resourceful in discrimination of anorthosite complex and associated rocks. The results obtained from ASTER and Sentinel-2A data processing were validated in field, followed by accuracy assessment