Multi-granularity locking for nested transactions

 The choice of granularity for locking items in a database involves performance trade-offs. In order to provide a choice between different locking granularities within a single system, the two-phase locking algorithm needs to be modified to include intention locks. This paper extends the well-known multi-granularity locking algorithm of Gray et al. to deal with nested transactions, and verifies the correctness of the extended algorithm, using a possibilities mapping to abstract commutativity-based locking. Received: June 4, 1993/November 28, 1994     

Novel high frequency pulsed MW-linear antenna plasma-chemistry: Routes towards large area, low pressure nanodiamond growth

Current experimental microwave plasma enhanced chemical vapour deposition (MW PECVD) concepts for diamond thin films do not allow scaling up towards large areas, which is essential for microelectronic industries. Also, current growth temperatures are rather high and not compatible with processing technologies. In the current work we demonstrate a breakthrough concept using a high frequency (HF) pulsed MW-linear antenna plasma configuration, allowing a scalable concept. By using HF pulses non-linear MW absorption conditions are reached, allowing a reduction of input power to 4 W/cm² compared with typically 100-200 W/cm² for resonance cavity applicators. Despite the factor of 50 power reduction, the growth rate obtained at 450 °C is comparable to or higher than that of resonance cavity systems. Our concept is a significant improvement as compared to [1,3] previous methods of nanodiamond growth. The resulting diamond films show columnar growth, i.e. resembling classical nano-crystalline diamond (NCD) films [3], with high crystallinity compatible with silicon on diamond chip technology. We present data from plasma diagnostics, showing HF pulsed data from optical emission spectroscopy (OES) for the CH₄-CO₂-H₂ gas chemistry and discuss the basic properties of the layers prepared. In comparison to the work [1] we have succeeded in suppression of re-nucleation during the growth and prepared high quality NCD films with 3-7% sp² carbon, depending on the growth conditions used, based on Raman measurements for layers as thin as 40 nm.     

Maximum Dispersion and Geometric Maximum Weight Cliques

We consider a facility location problem, where the objective is to disperse a number of facilities, i.e., select a given number k of locations from a discrete set of n candidates, such that the average distance between selected locations is maximized. In particular, we present algorithmic results for the case where vertices are represented by points in d-dimensional space, and edge weights correspond to rectilinear distances. Problems of this type have been considered before, with the best result being an approximation algorithm with performance ratio 2. For the case where k is fixed, we establish a linear-time algorithm that finds an optimal solution. For the case where k is part of the input, we present a polynomial-time approximation scheme.     

Replication-competent retroviral vectors encoding alkaline phosphatase reveal spatial restriction of viral gene expression/transduction in the chick embryo

Replication-competent avian retroviruses, capable of transducing and expressing up to 2 kb of nonviral sequences, are now available to effect widespread gene transfer in chicken (chick) embryos (S. H. Hughes, J. J. Greenhouse, C. J. Petropoulos, and P. Sutrave, J. Virol. 61:3004-3012, 1987). We have constructed novel avian retroviral vectors that encode human placental alkaline phosphatase as a marker whose expression can be histochemically monitored. These vectors have been tested for expression by introducing them into the embryonic chick nervous system. They have revealed that the expression of retrovirally transduced genes can be spatially and temporally limited without the need for tissue-specific promoters. By varying the site and time of infection, targeted gene transfer can be confined to selected populations of neural cells over the course of several days, a time window that is sufficient for many key developmental processes. The capability of differentially infecting specific target populations may avoid confounding variables such as detrimental effects of a transduced gene on processes unrelated to the cells or tissue of interest. These vectors and methods thus should be useful in studies of the effect of transduced genes on the development of various organs and tissues during avian embryogenesis. In addition, the vectors will facilitate studies aimed at an understanding of viral infection and expression patterns.     

Spectrophotometric method for determining the pigment content of ground paprika

A rapid and reliable method has been developed for determining the red, yellow and total pigment contents of ground paprika.     

Visual Analysis of Large Graphs: State‐of‐the‐Art and Future Research Challenges

The analysis of large graphs plays a prominent role in various fields of research and is relevant in many important application areas. Effective visual analysis of graphs requires appropriate visual presentations in combination with respective user interaction facilities and algorithmic graph analysis methods. How to design appropriate graph analysis systems depends on many factors, including the type of graph describing the data, the analytical task at hand and the applicability of graph analysis methods. The most recent surveys of graph visualization and navigation techniques cover techniques that had been introduced until 2000 or concentrate only on graph layouts published until 2002. Recently, new techniques have been developed covering a broader range of graph types, such as time‐varying graphs. Also, in accordance with ever growing amounts of graph‐structured data becoming available, the inclusion of algorithmic graph analysis and interaction techniques becomes increasingly important. In this State‐of‐the‐Art Report, we survey available techniques for the visual analysis of large graphs. Our review first considers graph visualization techniques according to the type of graphs supported. The visualization techniques form the basis for the presentation of interaction approaches suitable for visual graph exploration. As an important component of visual graph analysis, we discuss various graph algorithmic aspects useful for the different stages of the visual graph analysis process. We also present main open research challenges in this field.     

Curracurrong: a stream programming environment for wireless sensor networks

The technological advances in wireless sensor network (WSN) enable the development of complex applications including health monitoring, environmental sampling, and disaster area monitoring. WSN applications deploy battery‐powered sensors at remote locations for long periods. The development of energy‐efficient and complex WSN applications therefore requires in‐depth embedded systems programming skills that are normally not found in domain experts. So that this challenge can be overcome, programming environments for WSN need to offer a high degree of productivity, flexibility, and efficiency at the same time. In this work, we present Curracurrong, a development environment for WSNs that is based on expressing queries with stream programming. A query is represented as a stream graph consisting of stream operators and communication channels. Curracurrong provides an extensible stream operator library that adapts to a wide range of applications. It uses a novel placement algorithm that optimizes the energy consumption on sensor nodes. Through a case study, we demonstrate the productivity and flexibility of our system. We conduct experiments that evaluate the energy efficiency of our optimized operator placement algorithm. Copyright © 2012 John Wiley & Sons, Ltd.     

Online Square Packing with Gravity

We analyze the problem of packing squares in an online fashion: Given a semi-infinite strip of width 1 and an unknown sequence of squares of side length in [0,1] that arrive from above, one at a time. The objective is to pack these items as they arrive, minimizing the resulting height. Just like in the classical game of Tetris, each square must be moved along a collision-free path to its final destination. In addition, we account for gravity in both motion (squares must never move up) and position (any final destination must be supported from below). A similar problem has been considered before; the best previous result is by Azar and Epstein, who gave a 4-competitive algorithm in a setting without gravity (i.e., with the possibility of letting squares “hang in the air”) based on ideas of shelf packing: Squares are assigned to different horizontal levels, allowing an analysis that is reminiscent of some bin-packing arguments. We apply a geometric analysis to establish a competitive factor of 3.5 for the bottom-left heuristic and present a $\frac{34}{13} \approx 2.6154$ -competitive algorithm.