1,818 research outputs found
Angular reduction in multiparticle matrix elements
A general method for the reduction of coupled spherical harmonic products is
presented. When the total angular coupling is zero, the reduction leads to an
explicitly real expression in the scalar products within the unit vector
arguments of the spherical harmonics. For non-scalar couplings, the reduction
gives Cartesian tensor forms for the spherical harmonic products, with tensors
built from the physical vectors in the original expression. The reduction for
arbitrary couplings is given in closed form, making it amenable to symbolic
manipulation on a computer. The final expressions do not depend on a special
choice of coordinate axes, nor do they contain azimuthal quantum number
summations, nor do they have complex tensor terms for couplings to a scalar.
Consequently, they are easily interpretable from the properties of the physical
vectors they contain.Comment: This version contains added comments and typographical corrections to
the original article. Now 27 pages, 0 figure
X - Ray Flares and Their Connection With Prompt Emission in GRBs
We use a wavelet technique to investigate the time variations in the light
curves from a sample of GRBs detected by Fermi and Swift. We focus primarily on
the behavior of the flaring region of Swift-XRT light curves in order to
explore connections between variability time scales and pulse parameters (such
as rise and decay times, widths, strengths, and separation distributions) and
spectral lags. Tight correlations between some of these temporal features
suggest a common origin for the production of X-ray flares and the prompt
emission.Comment: 7th Huntsville Gamma-Ray Burst Symposium, GRB 2013: paper 15 in eConf
Proceedings C130414
Studies on the degranulation test for carcinogens
AbstractThe radiometric assay of degranulation of the hepatic endoplasmic reticulum by chemical carcinogens has been re-examined. Both 1,2,3,4,- and 1,25,6-dibenzanthracenes caused degranulation of rough membranes in vitro; with acetamidofluorenes and naphthylamines the carcinogenic analogues caused moderately greater degranulation. Degranulation by 1,2,3,4-dibenzantracene was rapid and was maximal after 5 min incubation. Pretreatment of animals with phenobarbital or methylcholanthrene increased the fraction of rough membranes, but these were not fully granulated. The assay is limited in specificity and sensitivity because the 1.35 M sucrose gradient does not effectively separate rough and smooth membranes, and sedimented membranes are contaminated with aggregates of free ribosomes
Trends in the use of payment instruments in the United States
In 2003, for the first time, the number of electronic payments in the United States exceeded the number of check payments--a result of substantial growth in electronic payments (especially by debit card) and a decline in check payments. The shift toward electronic payments suggests that, as with other large economies, many payments formerly made by check are now being made with electronic payment instruments. As in past years, however, the value of checks far exceeded the value of commonly used electronic payments. ; Comparisons among groups of depository institutions of different types and sizes suggest that the distribution of payments of different types is linked in part to the types of customers those institutions tend to serve. For example, at credit unions, which generally serve individuals rather than businesses, checks accounted for a smaller proportion of account debits, and debit card payments and ATM withdrawals accounted for a larger proportion, than at institutions of other types. ; Overall, "on us" check payments, those for which the payer and payee used the same institution, declined slightly. The rate at which checks are returned also declined, while the rate of returned ACH payments--almost twice that of checks--increased, in part because of new types of ACH payments, including ACH transactions initiated with a check. ; Data gathered in 2004 also reveal some differences among geographic regions. Debit card use was substantially greater, and check use substantially lower, in the West than in other regions. In contrast, debit card use was considerably less common in the Northeast, and the decline in check payments since 2000 was less pronounced in that region. ; Indirect evidence--data on ATM withdrawals and cash back from debit card payments--suggests that cash remains a popular means of making payments. Industry data showing increases in ATMs and ATM transactions appear to reflect a shift toward greater use of ATMs and less use of checks to obtain cash, and do not necessarily indicate an increase in the use of cash.Payment systems ; Checks
Scaling ansatz, four zero Yukawa textures and large
We investigate 'Scaling ansatz' in the neutrino sector within the framework
of type I seesaw mechanism with diagonal charged lepton and right handed
Majorana neutrino mass matrices (). We also assume four zero texture of
Dirac neutrino mass matrices () which severely constrain the
phenomenological outcomes of such scheme. Scaling ansatz and the present
neutrino data allow only Six such matrices out of 126 four zero Yukawa
matrices. In this scheme, in order to generate large we break
scaling ansatz in through a perturbation parameter and we also show our
breaking scheme is radiatively stable. We further investigate CP violation and
baryogenesis via leptogenesis in those surviving textures.Comment: 25 pages, 8 figures, Accepted for publication in Phys. Rev.
Complex Lithofacies Relationships between the Ste. Genevieve and Paoli Limestones: Clarifying Reservoir Relationships in the Indiana Subsurface
This poster was presented at the American Association of Petroleum Geologists (AAPG) Eastern Section Meeting in Evansville, Indiana,on September 22, 2009.Typically irregular vertical and lateral distribution of lithofacies within the Ste. Genevieve and Paoli
Limestones (Mississippian Blue River Group) has historically resulted in the inaccurate correlation
of uppermost Ste. Genevieve lithologies (Joppa Member) with Paoli units of similar composition and
appearance (Aux Vases and Renault Members). The Joppa Member of the Ste. Genevieve thins
northeastward toward the Illinois Basin margin, losing the distinctive log signature that characterizes
this unit in more basinward locations. The Aux Vases and Renault Members of the Paoli Limestone also
become difficult to distinguish from each other and from the Joppa Member in basin margin locations
because of rapid changes in composition and bed distribution. As a consequence, many Ste. Genevieve
and Paoli Limestone pay zones have been assigned to the wrong reservoir pool, sometimes within the
same field.
Pay zones from Ste. Genevieve and Paoli Limestone reservoirs were reassigned according to current
stratigraphic divisions. These new correlations more accurately reflect spatial relationships within and
between hydrocarbon pools, and could contribute to more effective reservoir management. Improved
correlations should also provide a useful tool for future hydrocarbon exploration and development
activities in Indiana. Our investigation also suggests that revisions to formal Ste. Genevieve-Paoli stratigraphic nomenclature should be considered
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