63,440 research outputs found
Equation of State in 2+1 Flavor QCD at High Temperatures
We calculate the Equation of State at high temperatures in 2+1 flavor QCD
using the highly improved staggered quark action. We study the lattice spacing
dependence of the pressure at high temperatures using lattices with temporal
extent and and perform continuum extrapolations. We
also give a continuum estimate for the Equation of State up to temperatures
GeV, which are then compared with results of the weak-coupling
calculations. We find a reasonably good agreement with the weak-coupling
calculations at the highest temperatures.Comment: RevTeX, 16 pages, 16 figures, published versio
Dependence of the thermoluminescent high-temperature ratio (HTR) of LiF:Mg,Ti detectors on proton energy and dose
The high-temperature ratio (HTR) is a parameter quantifying changes of the
shape of the high-temperature part of the LiF:Mg,Ti glow-curve after exposure
to densely ionizing radiation. It was introduced in order to estimate the
effective LET of an unknown radiation field and to correct the decreased
relative TL efficiency for high Linear Energy Transfer (LET) radiation. In the
present work the dependence of HTR on proton energy (14.5 to 58 MeV) and dose
(0.5 to 30 Gy) was investigated. All measured HTR values were at the level of
1.2 or higher, therefore significantly different from the respective value for
gamma rays (HTR is equal to 1), but HTR was found to be insensitive to changes
of proton energy above 20 MeV. As a result the relationship between HTR and
relative TL efficiency is not unequivocal. The HTR was found to be dependent on
absorbed dose even for the lowest studied doses.Comment: Manuscript has been presented at the 17th International Conference on
Solid State Dosimetry, Recife, Brasil, September 22-27,201
An Editor for Helping Novices to Learn Standard ML
This paper describes a novel editor intended as an aid in the learning of the functional programming language Standard ML. A common technique used by novices is programming by analogy whereby students refer to similar programs that they have written before or have seen in the course literature and use these programs as a basis to write a new program. We present a novel editor for ML which supports programming by analogy by providing a collection of editing commands that transform old programs into new ones. Each command makes changes to an isolated part of the program. These changes are propagated to the rest of the program using analogical techniques. We observed a group of novice ML students to determine the most common programming errors in learning ML and restrict our editor such that it is impossible to commit these errors. In this way, students encounter fewer bugs and so their rate of learning increases. Our editor, C Y NTHIA, has been implemented and is due to be tested on st..
Hot-carrier-induced deep-level defects from gated-diode measurements on MOSFETs
The reverse-bias current in the gated-diode configuration of hot-carrier degraded MOS devices was measured. It is shown that interface defects created by the degradation contribute predominantly to the generation current. The spatial distribution of the deep-level defects was obtained by means of device simulation
The 'gated-diode' configuration in MOSFET's, a sensitive tool for characterizing hot-carrier degradation
This paper describes a new measurement technique, the forward gated-diode current characterized at low drain voltages to be applied in MOSFET's for investigating hot-carrier stress-induced defects at high spatial resolution. The generation/recombination current in the drain-to-substrate diode as a function of gate voltage, combined with two-dimensional numerical simulation, provides a sensitive tool for detecting the spatial distribution and density of interface defects. In the case of strong accumulation, additional information is obtained from interband tunneling processes occurring via interface defects. The various mechanisms for generating interface defects and fixed charges at variable stress conditions are discussed, showing that information complementary to that available from other methods is obtaine
Pathways to double ionization of atoms in strong fields
We discuss the final stages of double ionization of atoms in a strong
linearly polarized laser field within a classical model. We propose that all
trajectories leading to non-sequential double ionization pass close to a saddle
in phase space which we identify and characterize. The saddle lies in a two
degree of freedom subspace of symmetrically escaping electrons. The
distribution of longitudinal momenta of ions as calculated within the subspace
shows the double hump structure observed in experiments. Including a symmetric
bending mode of the electrons allows us to reproduce the transverse ion
momenta. We discuss also a path to sequential ionization and show that it does
not lead to the observed momentum distributions.Comment: 10 pages, 10 figures; fig.6 and 7 exchanged in the final version
accepted for publication in Phys. Rev.
FLASH: Randomized Algorithms Accelerated over CPU-GPU for Ultra-High Dimensional Similarity Search
We present FLASH (\textbf{F}ast \textbf{L}SH \textbf{A}lgorithm for
\textbf{S}imilarity search accelerated with \textbf{H}PC), a similarity search
system for ultra-high dimensional datasets on a single machine, that does not
require similarity computations and is tailored for high-performance computing
platforms. By leveraging a LSH style randomized indexing procedure and
combining it with several principled techniques, such as reservoir sampling,
recent advances in one-pass minwise hashing, and count based estimations, we
reduce the computational and parallelization costs of similarity search, while
retaining sound theoretical guarantees.
We evaluate FLASH on several real, high-dimensional datasets from different
domains, including text, malicious URL, click-through prediction, social
networks, etc. Our experiments shed new light on the difficulties associated
with datasets having several million dimensions. Current state-of-the-art
implementations either fail on the presented scale or are orders of magnitude
slower than FLASH. FLASH is capable of computing an approximate k-NN graph,
from scratch, over the full webspam dataset (1.3 billion nonzeros) in less than
10 seconds. Computing a full k-NN graph in less than 10 seconds on the webspam
dataset, using brute-force (), will require at least 20 teraflops. We
provide CPU and GPU implementations of FLASH for replicability of our results
Heavy-fermion metals with hybridization nodes: Unconventional Fermi liquids and competing phases
Microscopic models for heavy-fermion materials often assume a local, i.e.,
momentum-independent, hybridization between the conduction band and the
local-moment f electrons. Motivated by recent experiments, we consider
situations where this neglect of momentum dependence is inappropriate, namely
when the hybridization function has nodes in momentum space. We explore the
thermodynamic and optical properties of the highly anisotropic heavy Fermi
liquid, resulting from Kondo screening in a higher angular-momentum channel.
The dichotomy in momentum space has interesting consequences: While e.g. the
low-temperature specific heat is dominated by heavy quasiparticles, the
electrical conductivity at intermediate temperatures is carried by unhybridized
light electrons. We then discuss aspects of the competition between Kondo
effect and ordering phenomena induced by inter-moment exchange: We propose that
the strong momentum-space anisotropy plays a vital role in selecting competing
phases. Explicit results are obtained for the interplay of unconventional
hybridization with unconventional, magnetically mediated, superconductivity,
utilizing variants of large-N mean-field theory. We make connections to recent
experiments on CeCoIn5 and other heavy-fermion materials.Comment: 16 pages, 8 figs, (v2) remark on Wiedemann-Franz added, small
changes, final version as publishe
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