19,138 research outputs found
Assessing technical candidates on the social web
This is the pre-print version of this Article. The official published version can be accessed from the link below - Copyright @ 2012 IEEEThe Social Web provides comprehensive and publicly available information about software developers: they can be identified as contributors to open source projects, as experts at maintaining weak ties on social network sites, or as active participants to knowledge sharing sites. These signals, when aggregated and summarized, could be used to define individual profiles of potential candidates: job seekers, even if lacking a formal degree or changing their career path, could be qualitatively evaluated by potential employers through their online
contributions. At the same time, developers are aware of the Webâs public nature and the possible uses of published information when they determine what to share with the world. Some might even try to manipulate public
signals of technical qualifications, soft skills, and reputation in their favor. Assessing candidates on the Web for
technical positions presents challenges to recruiters and traditional selection procedures; the most serious being the interpretation of the provided signals.
Through an in-depth discussion, we propose guidelines for software engineers and recruiters to help them interpret the value and trouble with the signals and metrics they use to assess a candidateâs characteristics and skills
A crystal base for the genetic code
The quantum enveloping algebra U_q(sl(2) \oplus sl(2)) in the limit q \to 0
is proposed as a symmetry algebra for the genetic code. In this approach the
triplets of nucleotids or codons in the DNA chain are classified in crystal
bases, tensor product of U_{q \to 0}(sl(2) \oplus sl(2)) representations. Such
a construction might be compared to the baryon classification from quark
building blocks in elementary particles physics, one of the main differences
standing in the property of a crystal base to provide a natural order in the
state constituents, this order being crucial in the codon. Then an operator
ensuring the correspondence codon/amino-acid can be constructed out of the
above algebra. It will be called the reading operator, and be such that two
codons relative to the same (resp. different) amino-acid(s) acquire the same
(resp. different) eigenvalue(s).Comment: LaTeX-2e document, package amsfonts, 11 page
Analytic approximations to the phase diagram of the Jaynes-Cummings-Hubbard model with application to ion chains
We discuss analytic approximations to the ground state phase diagram of the
homogeneous Jaynes-Cummings-Hubbard (JCH) Hamiltonian with general short-range
hopping. The JCH model describes e.g. radial phonon excitations of a linear
chain of ions coupled to an external laser field tuned to the red motional
sideband with Coulomb mediated hopping or an array of high- coupled cavities
containing a two-level atom and photons. Specifically we consider the cases of
a linear array of coupled cavities and a linear ion chain. We derive
approximate analytic expressions for the boundaries between Mott-insulating and
superfluid phases and give explicit expressions for the critical value of the
hopping amplitude within the different approximation schemes. In the case of an
array of cavities, which is represented by the standard JCH model we compare
both approximations to numerical data from density-matrix renormalization group
(DMRG) calculations.Comment: 9 pages, 5 figures, extended and corrected second versio
A quantitative assessment of empirical magnetic field models at geosynchronous orbit during magnetic storms
[1] We evaluate the performance of recent empirical magnetic field models (Tsyganenko, 1996, 2002a, 2002b; Tsyganenko and Sitnov, 2005, hereafter referred to as T96, T02 and TS05, respectively) during magnetic storm times including both pre- and post-storm intervals. The model outputs are compared with GOES observations of the magnetic field at geosynchronous orbit. In the case of a major magnetic storm, the T96 and T02 models predict anomalously strong negative Bz at geostationary orbit on the nightside due to input values exceeding the model limits, whereas a comprehensive magnetic field data survey using GOES does not support that prediction. On the basis of additional comparisons using 52 storm events, we discuss the strengths and limitations of each model. Furthermore, we quantify the performance of individual models at predicting geostationary magnetic fields as a function of local time, Dst, and storm phase. Compared to the earlier models (T96 and T02), the most recent storm-time model (TS05) has the best overall performance across the entire range of local times, storm levels, and storm phases at geostationary orbit. The field residuals between TS05 and GOES are small (â€3 nT) compared to the intrinsic short time-scale magnetic variability of the geostationary environment even during non-storm conditions (âŒ24 nT). Finally, we demonstrate how field model errors may affect radiation belt studies when estimating electron phase space density
Topological Speed Limits to Network Synchronization
We study collective synchronization of pulse-coupled oscillators interacting
on asymmetric random networks. We demonstrate that random matrix theory can be
used to accurately predict the speed of synchronization in such networks in
dependence on the dynamical and network parameters. Furthermore, we show that
the speed of synchronization is limited by the network connectivity and stays
finite, even if the coupling strength becomes infinite. In addition, our
results indicate that synchrony is robust under structural perturbations of the
network dynamics.Comment: 5 pages, 3 figure
Charmless Three-body Decays of B Mesons
Charmless 3-body decays of B mesons are studied in the framework of the
factorization approach. The nonresonant contributions arising from transitions are evaluated using heavy meson chiral perturbation theory
(HMChPT). The momentum dependence of nonresonant amplitudes is assumed to be in
the exponential form e^{-\alpha_{NR}} p_B\cdot(p_i+p_j)} so that the HMChPT
results are recovered in the soft meson limit . In addition, we
have identified another large source of the nonresonant signal in the matrix
elements of scalar densities, e.g. , which can be
constrained from the decay or . The
intermediate vector meson contributions to 3-body decays are identified through
the vector current, while the scalar meson resonances are mainly associated
with the scalar density. Their effects are described in terms of the
Breit-Wigner formalism. Our main results are: (i) All KKK modes are dominated
by the nonresonant background. The predicted branching ratios of
, and modes are consistent with the
data within errors. (ii) Although the penguin-dominated
decay is subject to a potentially significant tree pollution, its effective
is very similar to that of the mode. However, direct
CP asymmetry of the former, being of order -4%, is more prominent than the
latter. (iii) For decays, we found sizable nonresonant
contributions in and modes, in agreement
with the Belle measurements but larger than the BaBar result.Comment: 39 pages, 2 figures, version to appear in PR
Solar pond power plant feasibility study for Davis, California
The feasibility of constructing a solar pond power plant at Davis, California was studied. Site visits, weather data compilation, soil and water analyses, conceptual system design and analyses, a material and equipment market survey, conceptual site layout, and a preliminary cost estimate were studied. It was concluded that a solar pond power plant is technically feasible, but economically unattractive. The relatively small scale of the proposed plant and the high cost of importing salt resulted in a disproportionately high capital investment with respect to the annual energy production capacity of the plant. Cycle optimization and increased plant size would increase the economical attractiveness of the proposed concept
Structure and Innervation of the Equine Supraspinous and Interspinous Ligaments
Pain related to the osseous thoracolumbar spine is common in the equine athlete, with minimal information available regarding soft tissue pathology. The aims of this study were to describe the anatomy of the equine SSL and ISL (supraspinous and interspinous ligaments) in detail and to assess the innervation of the ligaments and their myofascial attachments including the thoracolumbar fascia. Ten equine thoracolumbar spines (T15âL1) were dissected to define structure and anatomy of the SSL , ISL and adjacent myofascial attachments. Morphological evaluation included histology, electron microscopy and immunohistochemistry (S100 and Substance P) of the SSL , ISL , adjacent fascial attachments, connective tissue and musculature. The anatomical study demonstrated that the SSL and ISL tissues merge with the adjacent myofascia. The ISL has a crossing fibre arrangement consisting of four ligamentous layers with adipose tissue axially. A high proportion of single nerve fibres were detected in the SSL (mean = 2.08 fibres/mm2) and ISL (mean = 0.75 fibres/mm2), with the larger nerves located between the ligamentous and muscular tissue. The oblique crossing arrangement of the fibres of the ISL likely functions to resist distractive and rotational forces, therefore stabilizing the equine thoracolumbar spine. The dense sensory innervation within the SSL and ISL could explain the severe pain experienced by some horses with impinging dorsal spinous processes. Documentation of the nervous supply of the soft tissues associated with the dorsal spinous processes is a key step towards improving our understanding of equine back pain
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