19,372 research outputs found
Comment: Bayesian Checking of the Second Level of Hierarchical Models: Cross-Validated Posterior Predictive Checks Using Discrepancy Measures
Comment: Bayesian Checking of the Second Level of Hierarchical Models
[arXiv:0802.0743]Comment: Published in at http://dx.doi.org/10.1214/07-STS235B the Statistical
Science (http://www.imstat.org/sts/) by the Institute of Mathematical
Statistics (http://www.imstat.org
On the Geometry of Moduli Space of Polarized Calabi-Yau manifolds
In this paper, we study the Chern classes on the moduli space of polarized
Calabi-Yau manifolds. We prove that the integrations of the invariants of the
curvature of the Weil-Petersson metric are finite. In some special cases, they
are even rational numbers
Power Side Channels in Security ICs: Hardware Countermeasures
Power side-channel attacks are a very effective cryptanalysis technique that
can infer secret keys of security ICs by monitoring the power consumption.
Since the emergence of practical attacks in the late 90s, they have been a
major threat to many cryptographic-equipped devices including smart cards,
encrypted FPGA designs, and mobile phones. Designers and manufacturers of
cryptographic devices have in response developed various countermeasures for
protection. Attacking methods have also evolved to counteract resistant
implementations. This paper reviews foundational power analysis attack
techniques and examines a variety of hardware design mitigations. The aim is to
highlight exposed vulnerabilities in hardware-based countermeasures for future
more secure implementations
Quasiparticles in the XXZ model
The coordinate Bethe ansatz solutions of the XXZ model for a one-dimensional
spin-1/2 chain are analyzed with focus on the statistical properties of the
constituent quasiparticles. Emphasis is given to the special cases known as XX,
XXX, and Ising models, where considerable simplifications occur. The XXZ
spectrum can be generated from separate pseudovacua as configurations of sets
of quasiparticles with different exclusion statistics. These sets are
complementary in the sense that the pseudovacuum of one set contains the
maximum number of particles from the other set. The Bethe ansatz string
solutions of the XXX model evolve differently in the planar and axial regimes.
In the Ising limit they become ferromagnetic domains with integer-valued
exclusion statistics. In the XX limit they brake apart into hard-core bosons
with (effectively) fermionic statistics. Two sets of quasiparticles with spin
1/2 and fractional statistics are distinguished, where one set (spinons)
generates the XXZ spectrum from the unique, critical ground state realized in
the planar regime, and the other set (solitons) generates the same spectrum
from the twofold, antiferromagnetically ordered ground state realized in the
axial regime. In the Ising limit, the solitons become antiferromagnetic domain
walls.Comment: 6 figure
Distribution, relative abundance and developmental morphology of paralarval cephalopods in the Western North Atlantic Ocean
Paralarval and juvenile cephalopods collected in plankton samples on 21 western North Atlantic cruises were identified and enumerated. The 3731 specimens were assigned to 44 generic and specific taxa. This paper describes their spatial and temporal distributions and their developmental morphology. The smallest paralarvae recognized for a
number of species are identified and illustrated. The two most abundant and most frequently collected taxa were identifiable to species based on known systematic characters
of young, as well as on distribution of the adults. These were the neritic squids Loligo pealeii and Illex illecebrosus collected north of Cape Hatteras, both valuable
fishery resources. Other abundant taxa included two morphotypes of ommastrephids, at least five species of enoploteuthids, two species of onychoteuthids, and unidentified octopods. Most taxa were distributed widely both in time and in space, although some seasonal and
mesoscale-spatial patterns were indicated. The taxa that appeared to have distinct seasonal distribution included most of the neritic species and, surprisingly, the young of the bathypelagic cranchiids. In eight seasonal cruises over the continental shelf of the middle U.S. Atlantic states,
neritic taxa demonstrated approximately the same seasonal patterns during two consecutive years. Interannual differences in the oceanic taxa collected on the shelf
were extreme. The highest abundance and diversity of planktonic cephalopods in the oceanic samples were consistently found in the vicinity of the Gulf Stream.
Only eight of the oceanic taxa appeared to have limited areal distributions, compared with twelve taxa that were found throughout the western North Atlantic regions
sampled in this study. Many taxa, however, were not collected frequently enough to describe seasonal or spatial patterns. Comparisons with published accounts of other cephalopod surveys indicate both strengths and weaknesses in various sampling techniques for capturing the young
of oceanic cephalopods. Enoploteuthids were abundant both in our study and in other studies using midwater trawls in several areas of the North Atlantic. Thus, this family probably is adequately sampled over its developmental range. In contrast, octopoteuthids and chtenopterygiids are rare in collections made by small to medium-sized midwater trawls but are comparatively common in plankton samples. For
families that are relatively common in plankton samples, paralarval abundance, derived similarly to the familiar ichthyoplankton surveys of fisheries science, may be the most reliable method of gathering data on distribution and abundance. (PDF file contains 58 pages.
Alignment methods for biased multicanonical sampling
The efficiency of the multicanonical procedure can be significantly improved by applying an additional bias to the numerically generated sample space. However, results obtained by biasing in different sampling regions cannot in general be accurately combined, since their relative normalization coefficient is not known precisely. We demonstrate that for overlapping biasing regions a simple iterative procedure can be employed to determine the required coefficients
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