3,126 research outputs found
Local available quantum correlations of X states: The symmetric and anti-symmetric cases
Local available quantum correlations (LAQC), as defined by Mundarain et al.,
are analyzed for 2-qubit X states with local Bloch vectors of equal magnitude.
Symmetric X-states are invariant under the exchange of subsystems, hence having
the same {local} Bloch vector. On the other hand, anti-symmetric X states have
{local} Bloch vectors with an equal magnitude but opposite direction
{(anti-parallel)}. In both cases, we obtain exact analytical expressions for
their LAQC quantifier. We present some examples and compare this quantum
correlation to concurrence and quantum discord. We have also included Markovian
decoherence, with Werner states under amplitude damping decoherence. As is the
case for depolarization and phase damping, no sudden death behavior occurs for
the LAQC of these states with this quantum channel.Comment: 11 pages, 7 figures, 1 appendi
CQESTR Simulation of Management Practice Effects on Long-Term Soil Organic Carbon
Management of soil organic matter (SOM) is important for soil productivity and responsible utilization of crop residues for additional uses. CQESTR, pronounced “sequester,” a contraction of “C sequestration” (meaning C storage), is a C balance model that relates organic residue additions, crop management, and soil tillage to SOM accretion or loss. Our objective was to simulate SOM changes in agricultural soils under a range of climate and management systems using the CQESTR model. Four long-term experiments (Champaign, IL, \u3e100 yr; Columbia, MO, \u3e100 yr; Lincoln, NE, 20 yr; Sidney, NE, 20 yr) in the United States under various crop rotations, tillage practices, organic amendments, and crop residue removal treatments were selected for their documented history of the long-term effects of management practice on SOM dynamics. CQESTR successfully simulated a substantial decline in SOM with 50 yr of crop residue removal under various rotations at Columbia and Champaign. The increase in SOM following addition of manure was simulated well; however, the model underestimated SOM for a fertilized treatment at Columbia. Predicted and observed values from the four sites were signifi cantly related (r2 = 0.94, n = 113, P \u3c 0.001), with slope not signifi cantly different from 1. Given the high correlation of simulated and observed SOM changes, CQESTR can be used as a reliable tool to predict SOM changes from management practices and offers the potential for estimating soil C storage required for C credits. It can also be an important tool to estimate the impacts of crop residue removal for bioenergy production on SOM level and soil production capacity
Vascular Changes in Popliteal Lymph Nodes due to Antigen Challenge in Normal and Lethally Irradiated Mice
The microvascular system of the murine popliteal lymph node was investigated using scanning electron microscopy of microcorrosion casts. Time-dependent changes in the microvasculature following regional antigen challenge in normal and lymphocyte-depleted mice were studied. Normal lymph node microvasculature exhibited a significant increase in both the vascular bed and post-capillary venules containing high-endothelium in response to antigen challenge. Lymph nodes of lymphocyte-depleted mice showed no microvascular size increase following antigen challenge and a reduction in the amount of high-endothelium was observed
EFFICIENT CONTENT NAVIGATION WITH A SINGLE DIMENSION OF INPUT
In general, the present disclosure describes navigating user interfaces that accept one-dimensional input, such as a vehicle dashboard console, a smart watch display, and/or the like. For example, a user interface may include a scrollable menu where the user is limited to just scrolling up or down the menu without dedicated next, previous, or select buttons. Rather than requiring a user to scroll all the way to a fixed location in the list, e.g. the top of the list, to navigate a menu hierarchy in order to select a back, select, next, up, close, or other affordance button, the techniques described herein may modify the user interface such that the affordance button is more easily accessible and may require fewer user inputs to navigate to and select. For example, the affordance button may be hidden until a user indicates an intent to activate the affordance button, the affordance button may remain at a top of the visible area of a scrollable menu even as the user scrolls the list beyond the first page of the list, or the affordance button may move around the user interface such that it remains adjacent to the cursor as the user navigates through the list
Eternal Symmetree
In this paper we introduce a simple discrete stochastic model of eternal
inflation that shares many of the most important features of the continuum
theory as it is now understood. The model allows us to construct a multiverse
and rigorously analyze its properties. Although simple and easy to solve, it
has a rich mathematical structure underlying it. Despite the discreteness of
the space-time the theory exhibits an unexpected non-perturbative analog of
conformal symmetry that acts on the boundary of the geometry. The symmetry is
rooted in the mathematical properties of trees, p-adic numbers, and ultrametric
spaces; and in the physical property of detailed balance. We provide
self-contained elementary explanations of the unfamiliar mathematical concepts,
which have have also appeared in the study of the p-adic string.
The symmetry acts on a huge collection of very low dimensional "multiverse
fields" that are not associated with the usual perturbative degrees of freedom.
They are connected with the late-time statistical distribution of
bubble-universes in the multiverse.
The conformal symmetry which acts on the multiverse fields is broken by the
existence of terminal decays - to hats or crunches - but in a particularly
simple way. We interpret this symmetry breaking as giving rise to an arrow of
time.
The model is used to calculate statistical correlations at late time and to
discuss the measure problem. We show that the natural cutoff in the model is
the analog of the so-called light-cone-time cutoff. Applying the model to the
problem of the cosmological constant, we find agreement with earlier work.Comment: 39 pages plus appendices, with 11 figures. Journal version (PRD). A
discussion of the arrow of time added, along with various other minor
clarifications suggested by an anonymous referee. References also adde
Topological Strings and Integrable Hierarchies
We consider the topological B-model on local Calabi-Yau geometries. We show
how one can solve for the amplitudes by using W-algebra symmetries which
encodes the symmetries of holomorphic diffeomorphisms of the Calabi-Yau. In the
highly effective fermionic/brane formulation this leads to a free fermion
description of the amplitudes. Furthermore we argue that topological strings on
Calabi-Yau geometries provide a unifying picture connecting non-critical
(super)strings, integrable hierarchies, and various matrix models. In
particular we show how the ordinary matrix model, the double scaling limit of
matrix models, and Kontsevich-like matrix model are all related and arise from
studying branes in specific local Calabi-Yau three-folds. We also show how
A-model topological string on P^1 and local toric threefolds (and in particular
the topological vertex) can be realized and solved as B-model topological
string amplitudes on a Calabi-Yau manifold.Comment: 82 pages, harvmac, 1 figur
AVALIAÇÃO DE SUBSTRATOS NA GERMINAÇÃO DE Plathymenia reticulata Benth.
O presente trabalho visa determinar o melhor substrato para a germinação emcondições de laboratório para sementes da espécie Plathymenia reticulada Benth. com afinalidade de formular regras para análise de sementes de espécies nativas. Para isso, agerminação câmaras BOD, modelo 347 CDG. Para os tratamentos foram utilizadosanteriormente caixas gerbox. Para os nove tratamentos foram utilizados substratos: areia, pretoterra, vermiculita, terra preta + areia (1:1), Black Earth + vermiculita (1:1), areia + vermiculita(1:1), areia + vermiculita + Black Earth (relação 1:1:1), papel absorvente e Folha de Papel. Paracada tratamento foram utilizadas 80 sementes. Foi realizada análise de variância (ANOVA) dosdados coletados, e as médias comparadas pelo teste de Tukey a 1% de significância, utilizando oprograma Versão Assistat 7.5 (2008). Os melhores substratos para a germinação foram areia,areia + vermiculita e vermiculita que tinha a maiores porcentagens de germinação, que são,respectivamente, 75,00%, 75,00% e 67,50% e os índices de taxa de germinação, que são,respectivamente, 4,49, 4, 32 e 3,96, estatisticamente indistinguíveis pelo teste de Tukey
A Seven-Layer Model of Collaboration: Separation of Concerns for Designers of Collaboration Systems
Designers of collaboration systems address many interrelated issues in a social-technical context. The volume, complexity, and variety of issues can invoke cognitive overload, causing deficiencies in system designs. We use inductive logic to derive seven key areas of concern for designers of collaboration support systems. We use deductive logic to argue that these areas address collaboration at differing levels of abstraction, and so may be organized into a seven-layer model, affording separation of concerns at design time. The layers are: Goals, Products, Activities, Patterns, Techniques, Tools, and Scripts. Design changes at one layer may not necessitate changes to layers above it, but may require changes to layers below it. At each layer and between each layer there are different issues and outcomes that may be addressed with different concepts, techniques and tools. This separation of concerns may reduce cognitive load for designers and may help to improve completeness and consistency of their designs, yielding higher productivity for collaborating groups
Moduli Entrapment with Primordial Black Holes
We argue that primordial black holes in the early universe can provide an
efficient resolution of the Brustein-Steinhardt moduli overshoot problem in
string cosmology. When the universe is created near the Planck scale, all the
available states in the theory are excited by strong interactions and
cosmological particle production. The heavy states are described in the low
energy theory as a gas of electrically and magnetically charged black holes.
This gas of black holes quickly captures the moduli which appear in the
relation between black hole masses and charges, and slows them down with their
vevs typically close to the Planck scale. From there, the modulus may slowly
roll into a valley with a positive vacuum energy, where inflation may begin.
The black hole gas will redshift away in the course of cosmic expansion, as
inflation evicts black holes out of the horizon.Comment: 14 pages latex, 7 .eps figures; v2: added references and a few
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