7,807 research outputs found

    Density Matrix Renormalization Group study of 48^{48}Cr and 56^{56}Ni

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    We discuss the development of an angular-momentum-conserving variant of the Density Matrix Renormalization Group (DMRG) method for use in large-scale shell-model calculations of atomic nuclei and report a first application of the method to the ground state of 56^{56}Ni and improved results for 48^{48}Cr. In both cases, we see a high level of agreement with the exact results. A comparison of the two shows a dramatic reduction in the fraction of the space required to achieve accuracy as the size of the problem grows.Comment: 4 pages. Published in PRC Rapi

    The Density Matrix Renormalization Group and the Nuclear Shell Model

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    We summarize recent efforts to develop an angular-momentum-conserving variant of the Density Matrix Renormalization Group method into a practical truncation strategy for large-scale shell model calculations of atomic nuclei. Following a brief description of the key elements of the method, we report the results of test calculations for 48^{48}Cr and 56^{56}Ni. In both cases we consider nucleons limited to the 2p-1f shell and interacting via the KB3 interaction. Both calculations produce a high level of agreement with the exact shell-model results. Furthermore, and most importantly, the fraction of the complete space required to achieve this high level of agreement goes down rapidly as the size of the full space grows

    A Hierarchical Relationship between the Fluence Spectra and CME Kinematics in Large Solar Energetic Particle Events: A Radio Perspective

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    We report on further evidence that solar energetic particles are organized by the kinematic properties of coronal mass ejections (CMEs)[1]. In particular, we focus on the starting frequency of type II bursts, which is related to the distance from the Sun where the radio emission starts. We find that the three groups of solar energetic particle (SEP) events known to have distinct values of CME initial acceleration, also have distinct average starting frequencies of the associated type II bursts. SEP events with ground level enhancement (GLE) have the highest starting frequency (107 MHz), while those associated with filament eruption (FE) in quiescent regions have the lowest starting frequency (22 MHz); regular SEP events have intermediate starting frequency (81 MHz). Taking the onset time of type II bursts as the time of shock formation, we determine the shock formation heights measured from the Sun center. We find that the shocks form on average closest to the Sun (1.51 Rs) in GLE events, farthest from the Sun in FE SEP events (5.38 Rs), and at intermediate distances in regular SEP events (1.72 Rs). Finally, we present the results of a case study of a CME with high initial acceleration (~3 km s^-2) and a type II radio burst with high starting frequency (~200 MHz) but associated with a minor SEP event. We find that the relation between the fluence spectral index and CME initial acceleration continues to hold even for this minor SEP event.Comment: 11 pages, 7 figures, 1 table, to appear in Journal of Physics: Conference Series (JPCS), Proceedings of the 16th Annual International Astrophysics Conference held in Santa Fe, NM, 201

    Preparation of Myrica nagi (Box myrtle) drink and effect of storage temperature on its quality

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    Box myrtle (Myrica nagi) belongs to family Myricaceae is a sub-temperate tree found throughout the mid-Himalayas at an elevation of 1300 to 2100 meters above mean sea level. Its fruits are known for their ravishing taste and have been reported as rich source of anti-oxidants like phenols and anthocyanins. In the present study drink was prepared from box myrtle juice and quality evaluation was carried out during six months of storage of fruit drink. Different combinations of juice (8%, 10%, 12%, 14% and 16 %) and sugar syrup/TSS (Total soluble solids) (12 oB and 15 oB) were tried to standardize proper combination for drink. The drink prepared by following the best selected recipe (14 % juice and 12 oB TSS) was packed in glass and PET (Polyethylene terephthalate) bottles and stored for six months under ambient and refrigerated temperature conditions. Drink could be safely stored for a period of six months under both the storage conditions without much change in various quality characteristics. Various physico-chemical characteristics increased/decreased like TSS (12.05 to 12.48 oB), reducing sugars (7.80 to 8.69 %), titratable acidity (0.30 to 0.27 %), ascorbic acid (1.09 to 0.47 mg/100 g), total phenols (27.35 to 19.11 mg/100 g) and anthocyanins (6.14 to 3.69 mg/100 g). However, the changes in the quality characteristics of the drink were slower in refrigerated storage conditions as compared to ambient conditions. Both the packaging materials viz. PET and glass bottles were found suitable, with comparatively less changes occurring in glass bottles stored under refrigerated conditions
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