7,322 research outputs found
The Density Matrix Renormalization Group and the Nuclear Shell Model
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 Cr and 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
Density Matrix Renormalization Group study of Cr and Ni
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 Ni and improved results for 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
A Hierarchical Relationship between the Fluence Spectra and CME Kinematics in Large Solar Energetic Particle Events: A Radio Perspective
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
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
Development of spiced squash (appetizer) from wild prickly pear (Opuntia dillenii Haw.) and its quality evaluation during storage
Wild prickly pear (Opuntia dillenii Haw.) is one of the wild fruit with great importance because of its high antioxidants, colour pigments and other quality parameters besides its medicinal properties. In India, there are only a limited number of reports pertaining to utilization of this fruit which further lack the development of value added novel products. So, the present studies were carried out for the development of spiced squash or appetizer from wild prickly pear fruit and its quality evaluation during storage. Different combinations of fruit juice (25, 30, 35 and 40 %) and sugar syrup (40 and 45 °B) were tried to standardize a proper combination for appetizer. The appetizer prepared by using the best recipe with 35 % juice, 45 °B TSS (Total soluble solids) and 1.20 % acidity was packed in two packaging materials viz. glass and PET (Polyethylene terephthalate) bottles which were further stored for six months under ambient and refrigerated temperature conditions. Appetizer packed in glass as well as in PET packaging material can be stored successfully for a period of six months under both the temperature conditions. However, various quality parameters of appetizer were retained higher in glass bottles stored under refrigerated storage conditions
Ground Level Enhancement in the 2014 January 6 Solar Energetic Particle Event
We present a study of the 2014 January 6 solar energetic particle (SEP)
event, which produced a small ground level enhancement (GLE), making it the
second GLE of this unusual solar cycle 24. This event was primarily observed by
the South Pole neutron monitors (increase of ~2.5%) whereas a few other neutron
monitors recorded smaller increases. The associated coronal mass ejection (CME)
originated behind the western limb and had the speed of 1960 km/s. The height
of the CME at the start of the associated metric type II radio burst, which
indicates the formation of a strong shock, was measured to be 1.61 Rs using a
direct image from STEREO-A/EUVI. The CME height at the time of GLE particle
release (determined using the South Pole neutron monitor data) was directly
measured as 2.96 Rs, from the STEREO-A/COR1 white-light observations. These CME
heights are consistent with those obtained for the GLE71, the only other GLE of
the current cycle as well as cycle-23 GLEs derived using back-extrapolation.
GLE72 is of special interest because it is one of the only two GLEs of cycle
24, one of the two behind-the-limb GLEs and one of the two smallest GLEs of
cycles 23 and 24
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