46,626 research outputs found
Constrained Jackiw-Rebbi model gives McGreevy-Swingle model
We show that the recently considered McGreevy-Swingle model for Majorana
fermions in the presence of a 't Hooft-Polyakov magnetic monopole arises when
the Jackiw-Rebbi model is constrained to be conjugation self dual.Comment: 3 page
Alternative conformal quantum mechanics
We investigate a one dimensional quantum mechanical model, which is invariant
under translations and dilations but does not respect the conventional
conformal invariance. We describe the possibility of modifying the conventional
conformal transformation such that a scale invariant theory is also invariant
under this new conformal transformation
Iterated smoothed bootstrap confidence intervals for population quantiles
This paper investigates the effects of smoothed bootstrap iterations on
coverage probabilities of smoothed bootstrap and bootstrap-t confidence
intervals for population quantiles, and establishes the optimal kernel
bandwidths at various stages of the smoothing procedures. The conventional
smoothed bootstrap and bootstrap-t methods have been known to yield one-sided
coverage errors of orders O(n^{-1/2}) and o(n^{-2/3}), respectively, for
intervals based on the sample quantile of a random sample of size n. We sharpen
the latter result to O(n^{-5/6}) with proper choices of bandwidths at the
bootstrapping and Studentization steps. We show further that calibration of the
nominal coverage level by means of the iterated bootstrap succeeds in reducing
the coverage error of the smoothed bootstrap percentile interval to the order
O(n^{-2/3}) and that of the smoothed bootstrap-t interval to O(n^{-58/57}),
provided that bandwidths are selected of appropriate orders. Simulation results
confirm our asymptotic findings, suggesting that the iterated smoothed
bootstrap-t method yields the most accurate coverage. On the other hand, the
iterated smoothed bootstrap percentile method interval has the advantage of
being shorter and more stable than the bootstrap-t intervals.Comment: Published at http://dx.doi.org/10.1214/009053604000000878 in the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
The inferior caval vein draining into the left atrial cavity : a rare case
The inferior vena cava (IVC) draining into the left atrium (LA) is exceedingly rare in the setting of the usual atrial arrangement (situs solitus). This article describes a patient with this unique anomaly, and its repair.peer-reviewe
Chemisorption on a model bcc metal
The system considered here is that of a single atom with one energy level chemisorbed on the (001) surface of a model bcc metal. We present the change in the density of electronic states În (E) due to chemisorption for two cases: one when the adatom is bound to a single substrate atom in the "onâsite" configuration and the other when it is bound to four substrate atoms in the "centered fourfold site." In principle, this change in the density of states În can be related to the results of photoemission measurements
Stress-Induced Delamination Of Through Silicon Via Structures
Continuous scaling of on-chip wiring structures has brought significant challenges for materials and processes beyond the 32 nm technology node in microelectronics. Recently three-dimensional (3-D) integration with through-silicon-vias (TSVs) has emerged as an effective solution to meet the future interconnect requirement. Thermo-mechanical reliability is a key concern for the development of TSV structures used in die stacking as 3-D interconnects. This paper examines the effect of thermal stresses on interfacial reliability of TSV structures. First, the three-dimensional distribution of the thermal stress near the TSV and the wafer surface is analyzed. Using a linear superposition method, a semi-analytic solution is developed for a simplified structure consisting of a single TSV embedded in a silicon (Si) wafer. The solution is verified for relatively thick wafers by comparing to numerical results obtained by finite element analysis (FEA). Results from the stress analysis suggest interfacial delamination as a potential failure mechanism for the TSV structure. Analytical solutions for various TSV designs are then obtained for the steady-state energy release rate as an upper bound for the interfacial fracture driving force, while the effect of crack length is evaluated numerically by FEA. Based on these results, the effects of TSV designs and via material properties on the interfacial reliability are elucidated. Finally, potential failure mechanisms for TSV pop-up due to interfacial fracture are discussed.Aerospace Engineerin
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