9,932 research outputs found
K-orbit closures on G/B as universal degeneracy loci for flagged vector bundles with symmetric or skew-symmetric bilinear form
We use equivariant localization and divided difference operators to determine
formulas for the torus-equivariant fundamental cohomology classes of -orbit
closures on the flag variety , where G = GL(n,\C), and where is one
of the symmetric subgroups O(n,\C) or Sp(n,\C). We realize these orbit
closures as universal degeneracy loci for a vector bundle over a variety
equipped with a single flag of subbundles and a nondegenerate symmetric or
skew-symmetric bilinear form taking values in the trivial bundle. We describe
how our equivariant formulas can be interpreted as giving formulas for the
classes of such loci in terms of the Chern classes of the various bundles.Comment: Minor revisions and corrections suggested by referees. Final version,
to appear in Transformation Group
Useful entanglement can be extracted from all nonseparable states
We consider entanglement distillation from a single-copy of a multipartite
state, and instead of rates we analyze the "quality" of the distilled
entanglement. This "quality" is quantified by the fidelity with the GHZ-state.
We show that each not fully-separable state can increase the "quality"
of the entanglement distilled from other states, no matter how weakly entangled
is . We also generalize this to the case where the goal is distilling
states different than the GHZ. These results provide new insights on the
geometry of the set of separable states and its dual (the set of entanglement
witnesses).Comment: 7 page
Instrument calibrates low gas-rate flowmeters
Electronically measuring the transit time of a soap bubble carried by the gas stream between two fixed points in a burette calibrates flowmeters used for measuring low gas-flow rates
Local unitary invariants for multipartite quantum systems
A method is presented to obtain local unitary invariants for multipartite
quantum systems consisting of fermions or distinguishable particles. The
invariants are organized into infinite families, in particular, the
generalization to higher dimensional single particle Hilbert spaces is
straightforward. Many well-known invariants and their generalizations are also
included.Comment: 13 page
Accountable Care Organizations in California: Promise and Performance
California has more accountable care organizations (ACOs) than any other state in the country, with particularly rapid growth over the past two years. This report introduces new evidence that ACOs improve the quality of care, increase patient satisfaction, and may reduce costs
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Trends in life cycle greenhouse gas emissions of future light duty electric vehicles
The majority of previous studies examining life cycle greenhouse gas (LCGHG) emissions of battery electric vehicles (BEVs) have focused on efficiency-oriented vehicle designs with limited battery capacities. However, two dominant trends in the US BEV market make these studies increasingly obsolete: sales show significant increases in battery capacity and attendant range and are increasingly dominated by large luxury or high-performance vehicles. In addition, an era of new use and ownership models may mean significant changes to vehicle utilization, and the carbon intensity of electricity is expected to decrease. Thus, the question is whether these trends significantly alter our expectations of future BEV LCGHG emissions. To answer this question, three archetypal vehicle designs for the year 2025 along with scenarios for increased range and different use models are simulated in an LCGHG model: an efficiency-oriented compact vehicle; a high performance luxury sedan; and a luxury sport utility vehicle. While production emissions are less than 10% of LCGHG emissions for today's gasoline vehicles, they account for about 40% for a BEV, and as much as two-thirds of a future BEV operated on a primarily renewable grid. Larger battery systems and low utilization do not outweigh expected reductions in emissions from electricity used for vehicle charging. These trends could be exacerbated by increasing BEV market shares for larger vehicles. However, larger battery systems could reduce per-mile emissions of BEVs in high mileage applications, like on-demand ride sharing or shared vehicle fleets, meaning that trends in use patterns may countervail those in BEV design
Integral Grothendieck-Riemann-Roch theorem
We show that, in characteristic zero, the obvious integral version of the
Grothendieck-Riemann-Roch formula obtained by clearing the denominators of the
Todd and Chern characters is true (without having to divide the Chow groups by
their torsion subgroups). The proof introduces an alternative to Grothendieck's
strategy: we use resolution of singularities and the weak factorization theorem
for birational maps.Comment: 24 page
Promoting Airport Walking: A Guide
A study found that signs placed in the Hartsfield-Jackson Atlanta International Airport to promote passengers walking to airport gates rather than taking shuttles resulted in several hundred more passengers a day choosing to walk (ceiling-mounted infrared sensors were used to count travelers entering and exiting the study location). The project was supported by Kresge and the Centers for Disease Control and Prevention. The study also produced a guide, "Promoting Airport Walking," intended primarily for airport managers who want their airports to encourage healthy habits and improve customer experiences
Superbroadcasting of mixed states
We derive the optimal universal broadcasting for mixed states of qubits. We
show that the nobroadcasting theorem cannot be generalized to more than a
single input copy. Moreover, for four or more input copies it is even possible
to purify the input states while broadcasting. We name such purifying
broadcasting superbroadcasting.Comment: 4 pages, 4 figures, to appear on Phys. Rev. Let
MODELING COUPON VALUES FOR READY-TO-EAT BREAKFAST CEREALS
A theoretical framework is developed to highlight the significant determinants of coupon values. A fixed effects panel data model is fitted with data from the breakfast cereal industry. The explanatory variables include own retail price, brand loyalty, brand market share, rival coupon redemptions, and firm and product type indicators.coupons, ready-to-eat breakfast cereals, panel data model, Consumer/Household Economics, Research Methods/ Statistical Methods,
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