Data encodings and their costs

Summary This paper is devoted to developing and studying a precise notion of the encoding of a logical data structure in a physical storage structure, that is motivated by considerations of computational efficiency. The development builds upon the notion of an encoding of one graph in another. The cost of such an encoding is then defined so as to reflect the structural compatibility of the two graphs, the (externally specified) costs of implementing the host graph, and the (externally specified) set of intended usage patterns of the guest graph. The stability of the constructed framework is demonstrated in terms of a number of results; the faithfulness of the formalism is argued in terms of a number of examples from the literature; and the tractability of the model is hinted at by several results and by further references to the literature.     

Drinking patterns as predictors of alcohol withdrawal reactions in DBA/2J mice

Individually housed DBA/2J mice were fed a liquid diet in which ethanol supplied 33% of the calories. The level of physical dependence that developed was estimated by scoring convulsions, elicited by handling the mice, after discontinuing the alcohol diet. The severity of the withdrawal reaction increased progressively with duration (5-12 days) of alcohol administration. A 2-day period on the diet produced no withdrawal reaction. Pretreatment of the mice with alcohol in their drinking water slightly increased the subsequent intake of the liquid diet. "Effective" alcohol intake was defined as uninterrupted alcohol consumption above 10 g/kg/day. Withdrawal scores correlated better with effective intake than with total intake under a variety of conditions. We interpret this to mean that brief interruptions in drinking (1 day) may allow the accrued physical dependence to disappear. On the basis of their effective alcohol intake, mice could be assigned to nondependent, moderately dependent or severely dependent groups for further study of the nature of physical dependence.     

Massenspektren alicyclischer Verbindungen. VI. Massenspektrometrisches Fragmentierungsverhalten von Chloressigsäurediestern des trans-1,4-Cyclohexandiols

Mass Spectra of Alicyclic Compounds. VI. Mass Spectrometric Fragmentation of Chloroacetic Esters of the trans-1,4-Cyclohexanediol The electron impact mass spectra of some chloroacetic esters of trans-1,4-cyclo-hexanediol and of cyclohexanol are discussed. It was found that the fragmentation process in these compounds is determined by the number of chlorine atoms in the acid and the interactions between the two functional groups.     

Comparison of different failure criteria for fiber-reinforced plastics in terms of fracture curves for arbitrary stress combinations

For fiber-reinforced plastics exists a big number of different criteria for the failure prediction. The intention of this paper is to compare the TSAI-HIL-, the LaRC04- and PUCK’s criterion in terms of their fracture curves for a unidirectional glass-fiber reinforced composite layer. Therefore after the implementation of these three criteria, the two-dimensional fracture curves for all possible stress combinations, which can be derived from a general spatial stress tensor, are computed. In this way, the characteristics of the criteria, similarities and differences and possible weak points become obvious.     

电源效率冲上电力市场浪尖？

政府机构正在与公用事业公司合作,减少由于低效率电源所导致的功耗增长。在今天的电力供应市场上,效率是一个热门话题。增加效率曾是一个被忽视的角色,但现在却是一个全球性的重要动向。这种转变有两个主要原因。     

Tunable 3D Nanoresonators for Gas‐Sensing Applications

The detection of gas species with high sensitivity is a significant task for fundamental sciences as well as for industrial applications. Similarly, the ongoing trend for device miniaturization brings new challenges for advanced fabrication including on‐demand functionality tuning. Following this motivation, here the additive, direct‐write fabrication of freestanding 3D nanoarchitectures is introduced, which can be brought into mechanical resonance via electric AC fields. Specifically, this study focuses on the 3D nanostructure synthesis, the subsequent determination of Young's modulus, and demonstrates a postgrowth procedure, which can precisely tune the material modulus. As‐fabricated resonators reveal a Young's modulus of 9–13 GPa, which can be increased by a factor greater than 5. Next, the electric readout of the resonance behavior is demonstrated via electric current measurement as an essential element for the resonance sensor applications. Finally, the implications of gas‐physisorption and gas‐chemisorption on the resonance frequencies are studied, representing a proof‐of‐principle for sensing applications by the here presented approach.     

PET regularization by envelope guided conjugate gradients

The authors propose a new way to iteratively solve large scale ill-posed problems and in particular the image reconstruction problem in positron emission tomography by exploiting the relation between Tikhonov regularization and multiobjective optimization to obtain iteratively approximations to the Tikhonov L-curve and its corner. Monitoring the change of the approximate L-curves allows the authors to adjust the regularization parameter adaptively during a preconditioned conjugate gradient iteration, so that the desired solution can be reconstructed with a small number of iterations.