Gapless points of dimerized quantum spin chains: analytical and numerical studies

We study the locations of the gapless points which occur for quantum spin chains of finite length (with a twisted boundary condition) at particular values of the nearest neighbor dimerization, as a function of the spin S and the number of sites. For strong dimerization and large values of S, a tunneling calculation reproduces the same results as those obtained from more involved field theoretic methods using the non-linear sigma-model approach. A different analytical calculation of the matrix element between the two Neel states gives a set of gapless points; for strong dimerization, these differ significantly from the tunneling values. Finally, the exact diagonalization method for a finite number of sites yields a set of gapless points which are in good agreement with the Neel state calculations for all values of the dimerization, but the agreement with the tunneling values is not very good even for large S. This raises questions about possible corrections to the tunneling results.Comment: Revtex4, 10 pages including 5 figure

Evaluation of metals release from oil sands coke : an ecotoxicological assessment of risk and hazard to aquatic invertebrates

The oil sands operations in northeast Alberta, Canada, employ unconventional processes to produce synthetic crude oil (SCO). Because the extracted bitumen, ¡®the form of oil in oil sands¡¯, is highly viscous, it requires thermal upgrading to produce SCO. Coking technology is used to convert heavy bitumen fractions to lighter volatile fractions. During this process, an enormous volume of solid coke is produced and the metal impurities (e.g. Al, Fe, Mn, Ni, Ti and V) present in bitumen fractions end-up in the coke particles. As coke demands significant space for storage, oil sands companies are exploring options for placing coke into reclamation landscapes for long term storage and recovery. However, coke holds appreciable amounts of potentially leachable metals that may impede the performance of reclamation landscapes. Although two previous coke leaching studies had showed that coke released metals into water at concentrations exceeding the Canadian guidelines for the protection of aquatic life, the ecotoxicological hazard and risk of these metals were not well characterized. Therefore, the overall goal of this research was to characterize the fate and toxicity of metals associated with coke. In this research, the toxicity of coke leachates collected from oil sands field sites and those artificially generated in the laboratory were evaluated using a standard three-brood Ceriodaphnia dubia tests. Coke leachates (CLs) collected over a period of 20 months from two field lysimeters were found to be acutely toxic to C. dubia. Vanadium concentrations were significantly higher (p¡Ü0.05) than concentrations of all other metals in CLs from both lysimeters, and also in leachates from a laboratory batch renewal leaching study. Furthermore, toxic unit (TU) calculations suggested that Ni and V were likely the cause of CL toxicity, but this was not explicitly proven. Therefore, a chronic toxicity identification and evaluation (TIE) approach was adopted to identify and confirm the cause(s) of CL toxicity. Coke was subjected to a 15 day batch leaching process in the laboratory at pH 5.5 and 9.5 in order to characterize the effect of pH on metals release from coke, and to generate CLs for use in TIE tests. The 7-day LC50 estimates for C. dubia survival were 6.3% and 28.7% (v/v) for CLs generated at pH 5.5 and 9.5, respectively. The dissolved concentrations of Mn, Ni and Zn were high (p¡Ü0.05) in pH 5.5 CL, whereas Al, Mo and V were high (p¡Ü0.05) in pH 9.5 CL. Evidence gathered from a series of chronic TIE tests revealed that Ni and V were the cause of toxicity in pH 5.5 CL, whereas V was the primary cause of toxicity in pH 9.5 CL. Further, the influence of bicarbonate, chloride and sulfate ions on metals release, speciation and Ni and V toxicity was investigated. The type and amount of metals released from coke was significantly influenced by the ion type elevated in the leaching solution. Specifically, sulfate influenced mobilization of Ni, Fe, Mn and Zn from coke, whereas bicarbonate enhanced Al, Mo and V releases from coke. With respect to toxicity, increasing bicarbonate decreased the 7-day Ni2+ IC50 from 6.3 to 2.3 ¦Ìg Ni2+/L suggesting enhanced Ni toxicity at high pH or alkalinity. Conversely, sulfate showed a protective effect against V toxicity to C. dubia. The research presented in this thesis suggests that coke will not be inert when stored in reclamation landscapes and that metals, particularly Ni and V, could reach ecotoxicologically relevant levels in surface waters or substrate porewaters, under favourable leaching conditions. Operationally, efforts should focus on remediation and monitoring of metals released from coke, particularly Ni and V, in impacted wetlands, especially before discharging water into natural wetlands and/or local streams and rivers

Morphological Analysis of the Human Internal Iliac Artery in South Indian Population

Objectives: The accidental hemorrhage is common due to erroneous interpretation of the variant arteries during surgical procedures, hence the present study has been undertaken with reference to its morphological significance. The objectives were to examine the level of origin, length and the branching pattern of the human internal iliac artery in South Indian population. Methods: The study included 60 human bisected pelvises irrespective of their side and sex. The specimens were collected from the anatomy laboratory and were fixed with the formalin. The branching patterns were studied and demonstrated as per the guidelines of Adachi. Results: The origin of internal iliac artery was at the level of S1 vertebra in majority (58.3%) of the cases. The average length of internal iliac artery was 37 ± 4.62 mm (range, 13-54 mm). The type I pattern of the internal iliac artery was most common (83.5%) followed by types III and II. The type IV and V pattern of adachi were not observed. Conclusions: The results of this study were different from those reported by others and may be because of racial and geographical variations. Prior knowledge of the anatomical variations is beneficial for the vascular surgeons ligating the internal iliac artery or its branches and the radiologists interpreting angiograms of the pelvic region

Power Generation System by using Piezo Sensors for Multiple Applications

Generally there is huge demand for power production. So going for alternative energy source is the best way to harvest electricity. We have proposed that piezo sensors produce electricity when pressure is applied on them. These sensors are then connected in series and parallel combination and placed in a tile like structure. This tile can be used in any place wherever pressure is applied. The harvested power can be stored in a battery and used for AC or DC loads and also voltage generated by a single tile can be displayed on display devices like LCD located at a different location using zigbee technology for smart analysis. DOI: 10.17762/ijritcc2321-8169.16041

A STUDY ON DRUG UTILIZATION PATTERN OF CEPHALOSPORINS IN GENERAL MEDICINE AND SURGICAL INPATIENT DEPARTMENT

Objective: Cephalosporins are a commonly used group of antibiotics in hospitals and healthcare facilities around the world. In the developed countries through the use of older cephalosporins is declining, that of the newer generations has increased. The objective of this study was to assess Drug Utilization Pattern of Cephalosporins in General Medicine and Surgical Inpatient Departments of tertiary care hospital.Methods: The data of enrolled patients were collected from case records of admitted inpatients during the study period. The collected data was assessed by statistical analysis using descriptive analysis.Results: A total of 110 inpatients were enrolled in the study. Out of 110 patients, males were 54.5% and females were 45.5%. The results analyzed that the prescriptions are more with third-generation cephalosporins than fourth-generation cephalosporins.Conclusion: The study concludes that 3rd generation cephalosporins is widely used for treating various nosocomial infections