551 research outputs found
Ground-State Energy and Spin Gap of Spin-1/2 Kagome Heisenberg Antiferromagnetic Clusters: Large Scale Exact Diagonalization Results
We present a comprehensive list of ground state energies and spin gaps of
finite kagome clusters with up to 42 spins obtained using large-scale exact
diagonalization techniques. This represents the current limit of this exact
approach. For a fixed number of spins N we study several cluster shapes under
periodic boundary conditions in both directions resulting in a toroidal
geometry. The clusters are characterized by their side length and diagonal as
well as the shortest "Manhattan" diameter of the torii. A finite-size scaling
analysis of the ground state energy as well as the spin gap is then performed
in terms of the shortest toroidal diameter as well as the shortest "Manhattan"
diameter. The structure of the spin-spin correlations further supports the
importance of short loops wrapping around the torii.Comment: 4 pages, 4 figures, added one referenc
Understanding the behavior of Pthread applications on non-uniform cache architectures
PosterWhy is it important? As number of cores in a processor scale up, caches would become banked Keeps individual look-up time small. Allows parallel accesses by different cores. Present shared programming model assumes a flat memory. Unaware application can have sub-optimal performance Conclusion Programming model needs to change For any heterogeneous memory hierarchy. Architecture, OS, compiler and application developer should work together Significant performance gains can be achieved. ? Without increasing system complexity. As complexity of memory hierarchy grows, optimizations like these will be critical
The business of educating the next generation of surgeons
Surgical education community needs to be informed about how education is funded and how it is threatened. In order to explore these issues the Association of Surgical Education convened a panel with significant experience in managing surgery departments to discuss the business of surgical education. They specifically addressed methods to recognize and reward faculty, educate residents on safety, quality and cost, and increase departmental revenue. This information is important in the current educational environment where there is an increased need for institutions to find alternate revenue streams to sustain graduate medical education. It is also important to find additional revenue streams to fund new residency slots to accommodate the greater number medical students who have been admitted to medical schools in response to meet the projected shortage of physicians
Formation and Primary Heating of The Solar Corona - Theory and Simulation
An integrated Magneto-Fluid model, that accords full treatment to the
Velocity fields associated with the directed plasma motion, is developed to
investigate the dynamics of coronal structures. It is suggested that the
interaction of the fluid and the magnetic aspects of plasma may be a crucial
element in creating so much diversity in the solar atmosphere. It is shown that
the structures which comprise the solar corona can be created by particle
(plasma) flows observed near the Sun's surface - the primary heating of these
structures is caused by the viscous dissipation of the flow kinetic energy.Comment: 46 pages including 7 pages of figures, Submitted to Phys.Plasma
Small-scale-field Dynamo
Generation of magnetic field energy, without mean field generation, is
studied. Isotropic mirror-symmetric turbulence of a conducting fluid amplifies
the energy of small-scale magnetic perturbations if the magnetic Reynolds
number is high, and the dimensionality of space d satisfies 2.103 < d <8.765.
The result does not depend on the model of turbulence, incompressibility and
isotropy being the only requirements.Comment: 11 pages Plain TeX, no figures, Accepted by Phys. Rev. Let
A New View on Worst-Case to Average-Case Reductions for NP Problems
We study the result by Bogdanov and Trevisan (FOCS, 2003), who show that
under reasonable assumptions, there is no non-adaptive worst-case to
average-case reduction that bases the average-case hardness of an NP-problem on
the worst-case complexity of an NP-complete problem. We replace the hiding and
the heavy samples protocol in [BT03] by employing the histogram verification
protocol of Haitner, Mahmoody and Xiao (CCC, 2010), which proves to be very
useful in this context. Once the histogram is verified, our hiding protocol is
directly public-coin, whereas the intuition behind the original protocol
inherently relies on private coins
Utilizing field collected insects for next generation sequencing: effects of sampling, storage and DNA extraction methods
DNA sequencing technologies continue to advance the biological sciences, expanding
opportunities for genomic studies of nonâmodel organisms for basic and applied
questions. Despite these opportunities, many next generation sequencing protocols
have been developed assuming a substantial quantity of high molecular weight DNA
(>100 ng), which can be difficult to obtain for many study systems. In particular, the
ability to sequence fieldâcollected specimens that exhibit varying levels of DNA degradation
remains largely unexplored. In this study we investigate the influence of
five traditional insect capture and curation methods on DoubleâDigest Restriction
Enzyme Associated DNA (ddRAD) sequencing success for three wild bee species.
We sequenced a total of 105 specimens (between 7â13 specimens per species and
treatment). We additionally investigated how different DNA quality metrics (including
preâsequence concentration and contamination) predicted downstream sequencing
success, and also compared two DNA extraction methods. We report successful
library preparation for all specimens, with all treatments and extraction methods producing
enough highly reliable loci for population genetic analyses. Although results
varied between species, we found that specimens collected by net sampling directly
into 100% EtOH, or by passive trapping followed by 100% EtOH storage before pinning
tended to produce higher quality ddRAD assemblies, likely as a result of rapid
specimen desiccation. Surprisingly, we found that specimens preserved in propylene
glycol during field sampling exhibited lowerâquality assemblies. We provide recommendations
for each treatment, extraction method, and DNA quality assessment,
and further encourage researchers to consider utilizing a wider variety of specimens
for genomic analysesinfo:eu-repo/semantics/publishedVersio
A Hypergraph Dictatorship Test with Perfect Completeness
A hypergraph dictatorship test is first introduced by Samorodnitsky and
Trevisan and serves as a key component in their unique games based \PCP
construction. Such a test has oracle access to a collection of functions and
determines whether all the functions are the same dictatorship, or all their
low degree influences are Their test makes queries and has
amortized query complexity but has an inherent loss of
perfect completeness. In this paper we give an adaptive hypergraph dictatorship
test that achieves both perfect completeness and amortized query complexity
.Comment: Some minor correction
Inositol phosphatase INPP4B sustains ILC1s and intratumoral NK cells through an AKT-driven pathway
Innate lymphoid cells (ILCs) are a heterogeneous population of lymphocytes that coordinate early immune responses and maintain tissue homeostasis. Type 1 innate immune responses are mediated by natural killer (NK) cells and group 1 ILCs (ILC1s). Despite their shared features, NK cells and ILC1s display profound differences among various tissue microenvironments. Here, we identify the inositol polyphosphatase INPP4B as a hallmark feature of tissue-resident ILC1s and intratumoral NK cells using an scRNA-seq atlas of tissue-associated and circulating NK/ILC1s. Conditional deletion of Inpp4b in ILC1s and NK cells reveals that it is necessary for the homeostasis of tissue-resident ILC1s but not circulating NK cells at steady-state. Inpp4b-deficient cells display increased rates of apoptosis and reduced activation of the prosurvival molecule AKT. Furthermore, expression of Inpp4b by NK/ILC1s is necessary for their presence in the intratumoral environment, and lack of Inpp4b impairs antitumor immunity. These findings highlight INPP4B as a novel regulator of tissue residency and antitumor function in ILC1s and NK cells
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