9,226 research outputs found
JVM-hosted languages: They talk the talk, but do they walk the walk?
The rapid adoption of non-Java JVM languages is impressive: major international corporations are staking critical parts of their software infrastructure on components built from languages such as
Scala and Clojure. However with the possible exception of Scala,
there has been little academic consideration and characterization
of these languages to date. In this paper, we examine four nonJava JVM languages and use exploratory data analysis techniques
to investigate differences in their dynamic behavior compared to
Java. We analyse a variety of programs and levels of behavior to
draw distinctions between the different programming languages.
We briefly discuss the implications of our findings for improving
the performance of JIT compilation and garbage collection on the
JVM platform
A Recursive Method for Determining the One-Dimensional Submodules of Laurent-Ore Modules
We present a method for determining the one-dimensional submodules of a
Laurent-Ore module. The method is based on a correspondence between
hyperexponential solutions of associated systems and one-dimensional
submodules. The hyperexponential solutions are computed recursively by solving
a sequence of first-order ordinary matrix equations. As the recursion proceeds,
the matrix equations will have constant coefficients with respect to the
operators that have been considered.Comment: To appear in the Proceedings of ISSAC 200
The Well Tempered Lasso
We study the complexity of the entire regularization path for least squares
regression with 1-norm penalty, known as the Lasso. Every regression parameter
in the Lasso changes linearly as a function of the regularization value. The
number of changes is regarded as the Lasso's complexity. Experimental results
using exact path following exhibit polynomial complexity of the Lasso in the
problem size. Alas, the path complexity of the Lasso on artificially designed
regression problems is exponential.
We use smoothed analysis as a mechanism for bridging the gap between worst
case settings and the de facto low complexity. Our analysis assumes that the
observed data has a tiny amount of intrinsic noise. We then prove that the
Lasso's complexity is polynomial in the problem size. While building upon the
seminal work of Spielman and Teng on smoothed complexity, our analysis is
morally different as it is divorced from specific path following algorithms. We
verify the validity of our analysis in experiments with both worst case
settings and real datasets. The empirical results we obtain closely match our
analysis.Comment: 16 pages, 2 figure
An Efficient Coal Pyrolysis Model for Detailed Tar Species Vaporization
An accurate and computationally efficient model for the vaporization of many tar species during coal particle pyrolysis has been developed. Like previous models, the molecular fragments generated by thermal decomposition are partitioned into liquid metaplast, which remains in the particle, and vapor, which escapes as tar, using a vapor-liquid equilibrium(VLE) sub-model. Multicomponent VLE is formulated as a rate-based process, which results in an ordinary differential equation (ODE) for every species. To reduce the computational expense of solving many ODEs, the model treats tar and metaplast species as a continuous distribution of molecular weight. To improve upon the accuracy of previous continuous thermodynamic approaches for pyrolysis, the direct quadrature method of moments (DQMoM) is proposed to solve for the evolving distributions without assuming any functional form. An inexpensive delumping procedure is also utilized to recover the time-dependent mole fractions and fluxes for every discrete species. The model is well-suited for coal-to-chemicals processes, and any application which requires information on a range of tar species. Using a modified CPD model as the basis for implementation of the VLE submodel, agreement between the full discrete model and DQMoM with delumping is excellent, with substantial computational savings
Neuronal and psychological underpinnings of pathological gambling
Like in the case of drugs, gambling hijacks reward circuits in a brain which is not prepared to receive such intense stimulation. Dopamine is normally released in response to reward and uncertainty in order to allow animals to stay alive in their environment – where rewards are relatively unpredictable. In this case, behavior is regulated by environmental feedbacks, leading animals to persevere or to give up. In contrast, drugs provide a direct, intense pharmacological stimulation of the dopamine system that operates independently of environmental feedbacks, and hence causes “motivational runaways”. With respect to gambling, the confined environment experienced by gamblers favors the emergence of excitatory conditioned cues, so that positive feedbacks take over negative feedbacks. Although drugs and gambling may act differently, their abnormal activation of reward circuitry generates an underestimation of negative consequences and promotes the development of addictive/compulsive behavior. In Parkinson’s and Huntington’s disease, dopamine-related therapies may disrupt these feedbacks on dopamine signalling, potentially leading to various addictions, including pathological gambling. The goal of this Research Topic is to further our understanding of the neurobiological mechanisms underlying the development of pathological gambling. This eBook contains a cross-disciplinary collection of research and review articles, ranging in scope from animal behavioral models to human imaging studies
Nonlinear projection filter for target tracking using range sensor & optical tracker
Target tracking filters have a variety of applications in various areas. Typically, a radar provides the range measurement and an optical sensor measures the orientation of a target. The measurements provided by the sensors have very strong nonlinearities with the states of the target given in the Cartesian coordinates while its dynamics is linear parameter time-varying. The time-varying component exists because of the unknown acceleration input in the target. Nonlinear projection filter provides a solution to the nonlinear estimation problem by approximating the solution as a linear combination of orthogonal basis functions. The analytic expression for propagating the joint probability density function is derived for the target tacking problem and this reduces large amount of computation times, where the filter equations are normally obtained numerically. The effectiveness of the filter is demonstrated by a numerical simulation
Electromagnetic probes of dense matter in heavy-ion collisions
Dilepton and photon production in heavy-ion collisions at SPS energies are
studied in the relativistic transport model that incorporates self-consistently
the change of hadron masses in dense matter. It is found that the dilepton
spectra in proton-nucleus reactions can be well described by the conventional
mechanism of Dalitz decay and direct vector meson decay. However, to provide a
quantitative explanation of the observed dilepton spectra in central heavy-ion
collisions requires contributions other than these direct decays and also
various medium effects. Introducing a decrease of vector meson masses in hot
dense medium, we find that these heavy-ion data can be satisfactorily
explained. Furthermore, the single photon spectra in our calculations with
either free or in-medium meson masses do not exceed the upper bound deduced
from the experiments by the WA80 Collaboration.Comment: 8 pages, including 4 postscript figures. Talk presented at Sixth
International Conference on Nucleus-Nucleus Collisions (NN97), Gatlinburg,
June, 1997, to appear in the proceeding
High Resolution Rydberg Spectroscopy of ultracold Rubidium Atoms
We present experiments on two-photon excitation of Rb atoms to
Rydberg states. For this purpose, two continuous-wave (cw)-laser systems for
both 780 nm and 480 nm have been set up. These systems are optimized to a small
linewidth (well below 1 MHz) to get both an efficient excitation process and
good spectroscopic resolution. To test the performance of our laser system, we
investigated the Stark splitting of Rydberg states. For n=40 we were able to
see the hyperfine levels splitting in the electrical field for different
finestructure states. To show the ability of spatially selective excitation to
Rydberg states, we excited rubidium atoms in an electrical field gradient and
investigated both linewidths and lineshifts. Furthermore we were able to excite
the atoms selectively from the two hyperfine ground states to Rydberg states.
Finally, we investigated the Autler-Townes splitting of the
5S5P transition via a Rydberg state to determine the Rabi
frequency of this excitation step.Comment: 9 pages, 7 figure
Magnetic Field induced Dimensional Crossover Phenomena in Cuprate Superconductors and their Implications
We discuss the occurrence of crossing points in the magnetization -
temperature ) plane within the framework of critical phenomena. It is
shown that in a two-dimensional superconducting slab of thickness
versus temperature curves measured in different fields
will cross at the critical
temperature T_c of the slab. In contrast, in a 3D anisotropic bulk
superconductor the crossing point occurs in the plot versus . The experimental facts that 2D crossing point
features have been observed in ceramics and in single crystals for
close to , but not for , is
explained in terms of an angle-dependent crossover field separating the regions
where 2D or 3D thermal fluctuations dominate. The measured 2D-crossing point
data are used to estimate one of the fundamental parameters of cuprate
superconductors, the minimum thickness of the slab , which remains
superconducting. Our estimates, based on experimental 2D-crossing point data
for single crystals, reveal that this length adopts material dependent values.
Therefore, experimental data for T_c and , plotted in
terms of T_c versus will not tend to a straight
line with universal slope as the underdoped limit is approached. Implications
for magnetic torque measurements are also worked out
Long-term yogurt consumption and risk of incident hypertension in adults
The Nurses' Health Study and Health Professionals Follow-up Study cohorts are supported by grants UM1 CA186107, UM1 CA176726, and UM1 CA167552 from the National Institutes of Health. The current analyses were supported by small grants from the National Dairy Council, the General Mills Bell Institute for Health and Nutrition, and the Boston Nutrition and Obesity Research Center. The Boston Nutrition Obesity Research Center is administratively based at Boston Medical Center and is funded by the National Institutes of Health (NIH/NIDDK) grant P30DK046200. (UM1 CA186107 - National Institutes of Health; UM1 CA176726 - National Institutes of Health; UM1 CA167552 - National Institutes of Health; small grants from the National Dairy Council; General Mills Bell Institute for Health and Nutrition; Boston Nutrition and Obesity Research Center; P30DK046200 - National Institutes of Health (NIH/NIDDK))Accepted manuscrip
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