bluuebunny/crossref_metadata_2025 huggingface dataset:
Synchronization and load imbalance effects in distributed memory multi‐processor systems
Authors: Marinescu Dan C. , Rice John R.
Published: November 2006

Synchronization is a major cause of wasted computing cycles and of diminished performance in parallel computing. This paper investigates the effects of synchronization upon the performance of iterative methods on distributed memory MIMD machines. A quantitative analysis of the effects of the communication latency and of the load imbalance due to the non‐deterministic execution times for iterative methods is presented. This analysis explains the rather poor performance observed often in actual implementations of such methods and suggests better ways to achieve convergence without frequent synchronization.
Physical computation
Authors: Fox Geoffrey C.
Published: November 2006

Physical computation embraces a variety of physical analogies used to tackle non‐traditional problems. We describe Monte Carlo and deterministic methods, including simulated annealing and neural networks. Applications include economic change in Eastern Europe, the travelling salesman problem, vehicle navigation, track finding, and parallel computer load balancing. We show how different problems are suitable for the different various approaches to optimizatton—there is no universally applicable method.
Achievements and prospects for parallel computing
Authors: Fox Geoffrey C.
Published: November 2006

Parallel computing works for the majority of large‐scale computations. The development of parallel hardware designs has been largely transferred to industry, while universities continue major research efforts Into better software environments. We describe a classification of problems and how different software models are needed for portable user‐friendly, high‐performance Implementations on parallel machines. The education of a new generation of computational scientists will be a major challenge to our universities.
Two‐level twisted preconditionings for parallel computers
Authors: Brugnano Luigi
Published: November 2006

A parallel preconditioned conjugate gradient (PCG) algorithm is derived by using a two‐level twisted factorization. The algorithm is optimal for a four‐processor parallel computer (quadputer). Numerical results obtained on a quadputer with distributed memory are presented.
A performance analysis exemplar: Parallel ray tracing
Authors: Jensen D. W. , Reed D. A.
Published: November 2006

Among the many techniques in computer graphics, ray tracing is prized because it can render realistic images, albeit at great computational expense. Ray tracing's large computation requirements, coupled with its inherently parallel nature, make ray tracing algorithms attractive candidates for parallel implementation. In this paper we illustrate the utility and the importance of a suite of performance analysis tools when exploring the performance of several approaches to ray tracing on a distributed memory parallel system. These ray tracing algorithm variations introduce parallelism based on both ray and object partitions.

Traditional timing analysis can quantify the performance effects of different algorithm choices (i.e. when an algorithm is best matched to a given problem), but it cannot identify the causes of these performance differences. We argue, by example, that a performance instrumentation system is needed that can trace the execution of distributed memory parallel programs by recording the occurrence of parallel program events. The resulting event traces can be used to compile summary stapistics that provide a global view of program performance. In addition, visualization tools permit the graphic display of event traces. Visual presentation of performance data is particularly useful, indeed, necessary for large‐scale, parallel computations; assimilating the enormous volume of performance data mandates visual display.
Highly efficient transputer arrays for the computation of robot dynamics
Authors: Zomaya Albert Y.
Published: November 2006

The modelling of the highly coupled and non‐linear dynamic models of robot manipulators is computationally expensive in terms of computer hardware. Hence this problem has always presented a major obstacle in on‐line dynamic control applications. However, the recent advent of the VLSI single on‐chip computer (Transputer) makes it possible to implement new algorithms that compute these dynamic models within real‐time constraints. This paper describes a solution of this problem by employing a parallel‐processing approach. The dynamic model of a robot manipulator is divided into different tasks. Further, each task is divided into several subtasks. A heuristic scheduling algorithm is used to produce different near‐optimum task allocations. Real‐time implementations of the proposed tasks allocations are given to demonstrate the efficiency and superiority of the parallel‐processing approach.
Parallelizing the spectral transform method
Authors: Worley Patrick H. , Drake John B.
Published: November 2006

The spectral transform method is a standard numerical technique used to solve partial differential equations on the sphere in global climate modeling. In particular, it is used in CCM1 and CCM2, the Community Climate Models developed at the National Center for Atmospheric Research. This paper describes initial experiences in parallelizing a program that uses the spectral transform method to solve the non‐linear shallow water equations on the sphere, showing that an efficient implementation is possible on the Intel iPSC/860. The use of PICL, a portable instrumented communication library, and Paragraph, a performance visualization tool, in tuning the implementation is also described.

The Legendre transform and the Fourier transform comprise the computational kernel of the spectral transform method. This paper is a case study of parallelizing the Legendre transform. For many problem sizes and numbers of processors, the spectral transform method can be parallelized efficiently by parallelizing only the Legendre transform.
Network‐based concurrent computing on the PVM system
Authors: Geist G. A. , Sunderam V. S.
Published: November 2006

Concurrent computing environments based on loosely coupled networks have proven effective as resources for multiprocessing. Experiences with and enhancements to version 1.0 of PVM (Parallel Virtual Machine) are described in this paper. PVM is a software package that allows the utilization of a heterogeneous network of parallel and serial computers as a single computational resource. This report also describes an interactive graphical interface to PVM, and porting and performance results from production applications.
Replication techniques for speeding up parallel applications on distributed systems
Authors: Bal Henri E. , Kaashoek M. Frans , Tanenbaum Andrew S. , Jansen Jack
Published: November 2006

Most methods for programming loosely coupled systems are based on message‐passing. Recently, however, methods have emerged based on ‘virtually’ sharing data. These methods simplify distributed programming, but are hard to implement efficiently, as loosely coupled systems do not contain physical shared memory. We introduce a new model,the shared data‐object model, that eases the implementation of parallel applications on loosely coupled systems, but can still be implemented efficiently.

In our model, shared data are encapsulated in passive data‐objects, which are variables of user‐defined abstract data types. To speed up access to shared data, data‐objects are replicated. This ability to replicate objects is a significant difference with other object‐based models (e.g. Emerald and Amber). Also, by replicating logical objects rather than physical pages, our model has many advantages over shared virtual memory systems.

This paper discusses the design choices involved in replicating objects and their effect on performance. Important issues are: how to maintain consistency among different copies of an object; how to implement changes to objects; which strategy for object replication to use. We have implemented several options to determine which ones are the most efficient.
Parallel computing in aerospace using multi‐block grids. Part 1: Application to grid generation
Authors: Húuser J. , Wong H. , Gentzsch W. , Paap H. G.
Published: November 2006

The present paper describes the implementation of multi‐block codes, used to model complex 2‐D geometries for applications in computational fluid dynamics on massively parallel architectures. The work starts with a brief description of ongoing and planned major aerospace projects and gives an estimate of the computing power needed. In order to provide this computational speed, one has to resort to massively parallel systems. In the first section the essential features of multi‐block grids, along with the grid generation equations are discussed and it is shown that overlapping multi‐block grids are inherently parallel by construction. Since the number of blocks is not fixed, but can be matched to a large extent to the number of available processors, there are no principal limitations of this parallelization approach, provided the ratio of computation time to communication time remains large enough, which leads to the discussion of problem scalability. The details of implementation on the Intel iPSC/2 of a general 2‐D multi‐block mesh‐generation code are outlined in sections 2 and 3, together with the listings of the major communication function (Section 4). In section 5 the results for this code are presented, clearly demonstrating that the multi‐block concept is a viable tool for massively parallel computers, which can be applied to virtually all problems in science and engineering where computational meshes are used. In section 5.2 an outlook on the parallelization of more complex problems is given, and estimates for speed‐up and efficiency, based on the present experiences, are provided. It turns out that, as long as computation dominates communication time, which is usually the case for complex aerospace applications, parallelization will be the tool to provide the additional orders of magnitude of computing power needed to routinely design and analyse future aircraft as well as spacecraft, in particular at high Mach numbers, when chemical reactions become important.
Echidna, an estelle compiler to prototype protocols on distributed computers
Authors: Jard Claude , Jezequel Jean‐Marc
Published: November 2006

We report our experience in developing a compiler and a distributed run‐time kernel for distributed computers, called Echidna. Echidna is a software package which has been available for more than two years, and aims to support protocol designers in protocol modeling, validation and performance evaluation. It is basically oriented towards the rapid prototyping of distributed algorithms on distributed computers: the Intel iPSC hypercube, the Supernode machine, and networks of Transputers and Suns were considered. Algorithms are described using an ISO formal description technique called Estelle.

First, we present and justify the concept of experimentation on distributed algorithms for which our Estelle compiler has been designed. Then we discuss how Estelle constructs are mapped onto C structures and how they are interpreted by a distributed run‐time kernel. We conclude by presenting typical uses of Echidna.
Transputer arrays for the on‐line computation of robot jacobians
Authors: Zomaya A. Y. H. , Morris A. S.
Published: November 2006

On‐line computation of forward and inverse Jacobian matrices is essential in robot manipulator controllers, where high‐speed robot motion is required. The complexity of Jacobian calculation is such that the computational burden is large, and parallel processing is necessary if on‐line computation is to be achieved. Various algorithms and parallel‐processing networks suitable for this are considered. All algorithms have been implemented on transputer networks and computation times measured. The paper emphasises the importance of including communication overheads in comparisons of the computational efficiency of alternative algorithms and processor networks. Theoretical processing times based on computer cycle times and arithmetic operation counts are shown to be a false basis for comparison.

Whilst considering the specific case of computation of Jacobian matrices for a robot manipulator, the paper provides a useful example of the considerations and constraints involved in distributing any algorithm across a multi‐processor network.
MOVIE model for open‐systems‐based high‐performance distributed computing
Authors: Furmanski Wojtek , Faigle Chris , Haupt Tom , Niemiec Janusz , Podgorny Marek , Simoni Diglio
Published: November 2006

MOVIE (Multitasking Object‐oriented Visual Interactive Environment) is a new software system for high‐performance distributed computing (HPDC), currently in the advanced design and implementation stage at Northeast Parallel Architectures Center (NPAC), Syracuse University. The MOVIE system is structured as a multiserver network of interpreters of the high‐level object‐oriented programming language MovieScript. MovieScript derives from PostScript and extends it in the C++ syntax‐based object‐oriented interpreted style towards 3D graphics, high‐performance computing and general‐purpose high‐level communication protocol for distributed and MIMD‐parallel computing. The paper describes the overall open systems‐based MOVIE design and itemizes currently implemented, developed and planned components of the system.
Particle simulation on heterogeneous distributed supercomputers
Authors: Becker Jeffrey C. , Dagum Leonardo
Published: November 2006

We describe the implementation and performance of a three dimensional particle simulation distributed between a Thinking Machines CM‐2 and a Cray Y‐MP. These are connected by a combination of two high‐speed networks: a high‐performance parallel Interface (HIPPI) and an optical network (UltraNct). This is the first application to use this configuration at NASA Ames Research Center. We describe our experience Implementing and using the application and report the results of several timing measurements. We show that the distribution of applications across disparate supcrcomputing platforms Is feasible and has reasonable performance. In addition, several practical aspects of the computing environment arc discussed.
Optimization techniques for SIMD Fortran compilers
Authors: Knobe Kathleen , Weiss Michael , Lukas Joan D.
Published: November 2006

SIMD computer systems offer tremendous potential speed‐ups but aggressive compilation strategies are required to realize this potential. The paper presents the Compass SIMD compiler technology developed while working on a number of SIMD compilers. Although the various targets have much in common, our increased understanding of the SIMD compilation process on each successive project and the differences in the targets themselves has affected the shape of each compiler.
Analysis and transformation in an interactive parallel programming tool
Authors: Kennedy Ken , McKinley Kathryn S. , Tseng Chau‐Wen
Published: November 2006

The ParaScope Editor is a new kind of interactive parallel programming tool for developing scientific Fortran programs. It assists the knowledgeable user by displaying the results of sophisticated program analyses and by providing editing and a set of powerful interactive transformations. After an edit or parallelism‐enhancing transformation, the ParaScope Editor incrementally updates both the analyses and source quickly. This paper describes the underlying implementation of the ParaScope Editor, paying particular attention to the analysis and representation of dependence information and its reconstruction after changes to the program.
Performance benefits of non‐volatile caches in distributed file systems
Authors: Biswas P. , Towsley D. , Ramakrishnan K. K. , Krishna C. M.
Published: November 2006

We study the use of non‐volatile memory for caching in distributed file systems. This provides an advantage over traditional distributed file systems in that the load is reduced at the server without making the data vulnerable to failures. We propose the use of a small non‐volatile cache for writes, at the client and the file server, together with a larger volatile read cache to keep the cost of the caches reasonable.

We use a synthetic workload developed from analysis of file I/O traces from commercial production systems and use a detailed simulation of the distributed environment. The service times for the resources of the system were derived from measurements performed on a typical workstation.

We show that non‐volatile write caches at the clients and the file server reduce the write response time and the load on the file server dramatically, thus improving the scalability of the system. We examine the comparative benefits of two alternative writeback policies for the non‐volatile write cache. We show that a proposed threshold based writeback policy is more effective than a periodic writeback policy under heavy load. We also investigate the effect of varying the write cache size and show that introducing a small non‐volatile cache at the client in conjunction with a moderate sized non‐volatile server write cache improves the write response time by a factor of four at all load levels.
The Prospero Resource Manager: A scalable framework for processor allocation in distributed systems
Authors: Neuman B. C. , Rao S.
Published: November 2006

Existing techniques for allocating processors in parallel and distributed systems are not suitable for use in large distributed systems. In such systems, dedicated multiprocessors should exist as an integral component of the distributed system, and idle processors should be available to applications that need them. The Prospero Resource Manager (PRM) is a scalable resource allocation system that supports the allocation of processing resources in large networks and on multiprocessor systems.

PRM employs three types of managers‐the job manager, the system manager and the node manager‐to manage resources in a distributed system. Multiple independent instances of each type of manager exist, reducing bottlenecks. When making scheduling decisions each manager utilizes information most closely associated with the entities for which it is responsible.
Adaptive transport service for high speed networks
Authors: Richards A. , Ginige T. , Seneviratne A. , Buczkowska T. , Fry M.
Published: November 2006

It has been shown that protocol processing represents a severe bottle‐neck for high speed computer networks. The disadvantages of currently proposed solutions are their incompatibility with existing standardised protocol implementations, their complexity and/or their inflexibility. One method of alleviating these limitation is to have an adaptable protocol stack, as proposed in the paper. Preliminary results are presented which show that significant gains in throughput can be achieved while creating a framework suitable for future applications.
Matrix multiplication on the Intel Touchstone Delta
Authors: Huss‐Lederman Steven , Jacobson Elaine M. , Tsao Anna , Zhang Guodong
Published: November 2006

Matrix multiplication is a key primitive in block matrix algorithms such as those found in LAPACK. We present results from our study of matrix multiplication algorithms on the Intel Touchstone Delta, a distributed memory message‐passing architecture with a two‐dimensional mesh topology. We analyze and compare three algorithms and obtain an implementation, BiMMeR, that uses communication primitives highly suited to the Delta and exploits the single node assembly‐coded matrix multiplication. Our algorithm is completely general, i.e. able to deal with various data layouts as well as arbitrary mesh aspect ratios and matrix dimensions, and has achieved parallel efficiency of 86 %, with overall peak performance in excess of 8 Gflops on 256 nodes for an 8800 × 8800 matrix. We describe BiMMeR's design and implementation and present performance results that demonstrate scalability and robust behavior over varying mesh topologies.
Determining update latency bounds in Galactica Net
Authors: Clayton S. , Wilson A. , Duckworth R. J. , Michalson W.
Published: November 2006

The paper looks at the problem of ensuring the performance of real‐time applications hosted on Galactica Net, a mesh‐based distributed cache coherent shared memory multiprocessing system. A method for determining strict upper bounds on worst case latencies in wormhole routed networks of known or unknown communication patterns is presented. From this, a tool for determining upper bounds for shared memory update latencies is developed, and it is shown that the update latency of Galactica Net is deterministic. The analytical bounds are then compared with maximum latencies observed in simulations of GNet, with which they compare favorably. Finally, it is shown that the tool for determining update latency bounds is useful for comparing differing GNet system configurations in order to minimize update latency bounds.
Instructional footprinting and semantic preservation in Linda
Authors: Landry Kenneth , Arthur James D.
Published: November 2006

Linda is a co‐ordination language designed to support process creation and interprocess communication within conventional computational languages. Although the Linda paradigm touts architectural and language independence, it often suffers performance penalties, particularly on local area network platforms. Instructional footprinting is an optimization technique with the primary goal of enhancing the execution speed of Linda programs. The two main aspects of instructional footprinting are instructional decomposition and code motion. The paper addresses the semantic issues encountered when the Linda primitives, IN and RD, are decomposed and moved past other Linda operations. Formal semantics are given as well as results showing significant speed‐up (as high as 100%) when instructional footprinting is used.
A parallel dynamic load‐balancing algorithm for solution‐adaptive finite element meshes on 2D tori
Authors: Chung Yeh‐Ching , Yeh Yaa‐Jyun , Liu J.‐S
Published: November 2006

To efficiently execute a finite element program on a 2D torus, we need to map nodes of the corresponding finite element graph to processors of a 2D torus such that each processor has approximately the same amount of computational load and the communication among processors is minimized. If nodes of a finite element graph do not increase during the execution of a program, the mapping only needs to be performed once. However, if a finite element graph is solution‐adaptive, that is, nodes of a finite element graph increase discretely due to the refinement of some finite elements during the execution of a program, a dynamic load‐balancing algorithm has to be performed many times in order to balance the computational load of processors while keeping the communication cost as low as possible. In the paper we propose a parallel dynamic load‐balancing algorithm (LB) to deal with the load‐imbalancing problem of a solution‐adaptive finite element program on a 2D torus. The algorithm uses an iterative approach to achieve load‐balancing. We have implemented the proposed algorithm along with two parallel mapping algorithms, parallel orthogonal recursive bisection (ORB) and parallel recursive mincut bipartitioning (MC), on a simulated 2D torus. Three criteria, the execution time of load‐balancing algorithms, the computation time of an application program under different load balancing algorithms, and the total execution time of an application program (under several refinement phases) are used for performance evaluation. Simulation results show that (1) the execution of LB is faster than those of MC and ORB; (2) the mappings of LB are better than those of ORB and MC; and (3) the speedups of LB are better than those of ORB and MC.
Symmetrical hopping: A scalable scheduling algorithm for irregular problems
Authors: Wu Min‐You
Published: November 2006

A run‐time support is necessary for parallel computations with irregular and dynamic structures. One important component in the support system is the run‐time scheduler which balances the working load in the system. We present a new algorithm, Symmetrical Hopping, for dynamic scheduling of ultra‐lightweight processes. It is a dynamic, distributed, adaptive and scalable scheduling algorithm. This algorithm is described and compared to four other algorithms that have been proposed in this context, namely the randomized allocation, the sender‐initiated scheduling, the receiver‐initiated scheduling, and the gradient model. The performance of these algorithms on Intel Touchstone Delta is presented. The experimental results show that the Symmetrical Hopping algorithm achieves much better performance due to its adaptiveness.
Uplink PID power control technique for TDMA‐based cellular radio systems
Authors: Weng Chien‐Erh , Lain Jenn‐Kaie , Shen Chia‐Huei , Wen Jyh‐Horng
Published: November 2006

The efficient management of wireless resource is essential to the success of wireless systems. While power control is traditionally considered to be a means to counteract the detrimental effects of channel fading, it is also a flexible mechanism that achieves high link quality, high bandwidth utilization, and low power consumption, which are mainly driven in cellular radio systems. Once the power control algorithm provides a lower outage probability, the SUs experienced adequate link quality need not to competitively increase their transmission power. Spontaneously, the systems with lower power consumption and better bandwidth efficiency are achieved. In this paper, a novel power control based on the proportional‐integration‐derivative (PID) controller is proposed, and its performance with an autonomous closed‐loop uplink power control model under the time division multiple access (TDMA) systems is presented. Computer simulation is used to illustrate the performance of the proposed power control algorithm in a cellular radio system with Rayleigh fading channels. The results show that our proposed power control algorithm is remarkably superior to several previous power control methods, especially in a short power control period. Copyright © 2006 John Wiley & Sons, Ltd.
Adiponectin as a therapeutic target for obesity‐related metabolic and cardiovascular disorders
Authors: Wang Yu , Lam Karen S.L. , Xu Aimin
Published: November 2006

Obesity is the major risk factor for the metabolic syndrome, which encompasses a cluster of inter‐related metabolic risk factors for type 2 diabetes mellitus (T2DM), atherosclerosis, and cardiovascular diseases. Adiponectin, a major adipokine secreted from adipocytes, plays an important role in obesity‐related metabolic and cardiovascular diseases. Longitudinal studies from different ethnic groups have identified low levels of plasma adiponectin (hypoadiponectinemia) to be an independent risk factor for T2DM, hypertension, and coronary artery diseases. On the other hand, results from various animal models have demonstrated the role of adiponectin as an insulin‐sensitizer with potent anti‐diabetic, anti‐atherogenic, anti‐inflammatory, and cardio‐protective activities. Therefore, upregulation of endogenous adiponectin production by pharmacological and/or dietary interventions might have multiple beneficial effects on obesity‐related disorders. A number of pharmacological agents that increase adiponectin production have recently been identified. Among them, the anti‐diabetic actions of the PPARγ agonists, thiazolidinediones (TZDs), are mediated, at least in part, by induction of adiponectin expression. Here, we summarize the recent progress on clinical and pharmacological studies of adiponectin, and discuss the utility of adiponectin as a target to develop novel therapies for treatment and prevention of obesity‐related metabolic and cardiovascular diseases. Drug Dev. Res. 67:677–686, 2006. © 2006 Wiley‐Liss, Inc.
Recent progress on geometric algorithms for approximating functions: Toward applications to data analysis
Authors: Tokuyama Takeshi
Published: November 2006

Data simplification is an extremely important issue in our current information‐oriented society. Normally, a real‐world database contains a massive amount of raw data, and when we consider the data as a distribution function, it has fluctuations due to sampling errors, outliers, and/or invalid inputs. Therefore, for data analysis technology such as data mining, it is important to approximate the input data by a simplified function. There are various approaches to function approximation, and functional analytical methods and learning‐based techniques are quite popular. Apart from them, computational geometric approach based on optimization using discrete algorithms is widely studied. However, the conventional application of computational geometrical techniques is pattern matching, and to apply them to data analysis, their formulation and optimization criteria must be changed accordingly. Therefore, various difficulties and computational barriers arise, which must be eliminated or avoided. In this paper, we discuss data approximation in computational geometry and describe current trends centered on the author's latest research. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 90(3): 1–12, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.20297
Ionic dispersion in nanofluidics
Authors: De Leebeeck Angela , Sinton David
Published: November 2006

An analytical solution for dispersion of ionic and neutral solutes in nanoscale channels is presented. Results suggest that in the presence of relatively thick electrical double layers (EDLs) characteristic of nanofluidics, the dispersion of ionic solutes differs from that of neutral solutes on which previous theory is based. Ionic dispersion for circular cross‐section channels is quantified as a function of a valance parameter, the relative EDL thickness, and the form of the velocity profile. Two unique mechanisms governing ionic dispersion in both pressure‐ and electrokinetically driven flows are identified. The results of the analytical solution, employing the linearized form of the Poisson–Boltzmann equation, are supported and extended by the results of an independent computational model employing the nonlinear Poisson–Boltzmann equation. Applicability of the computational results is not limited by the Debye–Hückel approximation. Collectively, these results indicate that dispersion of ionic species in nanoscale channels is markedly charge dependent, and substantially deviates from that of neutral solutes in the same flow.
Microchip electrophoresis with wall‐jet electrochemical detector: Influence of detection potential upon resolution of solutes
Authors: Pumera Martin , Merkoçi Arben , Alegret Salvador
Published: November 2006

This report studies the electrochemical response of wall‐jet detector for microchip electrophoresis (µCE). It shows that in wall‐jet configuration, the electrochemical detector operates in coulometric mode and that there is an influence of detection potential upon peak width and therefore upon the resolution of solutes. Upon raising the detection potential from +0.3 to +0.9 V, the resolution between model analytes, dopamine and catechol, increases from 0.63 to 2.90. The reasons for this behavior originate in wall‐jet detector design and in its typically significant higher detector volume than the volume of injected sample. The conversion efficiency of the wall‐jet electrochemical detection cell was found to be 97.4% for dopamine and 98.0% for catechol. The paper brings deeper understanding of operations of wall‐jet electrochemical detectors for microchip devices, and it explains previously reported significantly sharper peaks when electrocatalytic electrodes (i.e., palladium and carbon nanotube) were used in µCE‐electrochemistry wall‐jet detector.
Production of Iridoids and Phenolics by Transformed Harpagophytum procumbens Root Cultures
Authors: Georgiev M. , Heinrich M. , Kerns G. , Pavlov A. , Bley T.
Published: November 2006

Harpagophytum procumbens (Devil's claw) is an important medicinal plant, which tubers are used for the treatment of different inflammatory diseases. In this study, the time courses of growth of Devil's claw hairy roots and accumulation of intracellular total iridoids and phenolics were investigated during cultivation under submerged conditions. After 21 days of growth in liquid hormone‐free MS medium, a growth index of 81.3 was achieved and the accumulated biomass reached 0.58 g/flask. It was found that the time courses of total iridoids and phenolics production showed almost the same patterns with a maximum on day 21 from the beginning of cultivation (15.93 mg harpagoside equivalents/L and 261 mg gallic acid equivalents/L, respectively). The methanolic extracts possessed relatively high DPPH‐radical scavenging properties (IC50 4.08 mg/mL), while for the culture media no antiradical activity was detected. According to our best knowledge, the present report is the first one dealing with the investigation of transformed root cultures from Harpagophytum procumbens plants.
Adsorption of pure carbon dioxide and methane on dry coal from the sulcis coal province (SW Sardinia, Italy)
Authors: Ottiger Stefan , Pini Ronny , Storti Giuseppe , Mazzotti Marco , Bencini Roberto , Quattrocchi Fedora , Sardu Giorgio , Deriu Giuseppe
Published: November 2006

Enhanced coalbed methane recovery (ECBM) increases the recovery of the methane present in a coal seam by injecting CO2 at high pressure. It is attractive from two perspectives, the valuable methane recovered and the storage of the greenhouse gas CO2 for geological times. In the framework of a feasibility study for the Sulcis Coal Province in Italy, the adsorption of pure CO2 and CH4 on dry coal has been measured at 45 and 60°C, using a magnetic suspension balance with in situ density measurement. The results show that the CO2 adsorption isotherms on coal are similar to those for other standard adsorbents such as silica gel and activated carbon. From the excess adsorption isotherms, the absolute adsorption is calculated using the assumption of constant volume of the adsorbed phase. As expected, CO2 get adsorbed more than CH4 in all cases. The Sulcis coal can uptake CO2 at the reservoir conditions in an amount of about 10% of its mass. © 2006 American Institute of Chemical Engineers Environ Prog, 2006
The incidence of first‐onset psychotic symptoms and paranoid ideation in a representative population sample followed from age 70–90 years. Relation to mortality and later development of dementia
Authors: Östling S. , Pálsson S. P. , Skoog I.
Published: November 2006

Background

Limited data are available on the incidence of psychotic symptoms in the elderly.

Objective

To elucidate the incidence of first‐onset psychotic symptoms in the elderly and their relation to mortality and later development of dementia.

Method

A population‐sample (n = 392) born 1901–1902 was assessed from age 70–90 with psychiatric examinations, medical record reviews and from age 85, also with key‐informant interviews. Individuals developing dementia were excluded.

Result

The cumulative incidence of first‐onset psychotic symptoms was 4.8% (8.0% including key‐informant reports in the total sample) and 19.8 % in those who survived to age 85. Sixty‐four percent of those with first‐onset hallucinations later developed dementia, compared to 30% of those with delusions and 25% of those without psychotic symptoms.

Conclusions

One fifth of non‐demented elderly who survives up to age 85 develops first‐onset psychotic symptoms. Hallucinations predict dementia, but most elderly individuals with first‐onset psychotic symptoms do not develop dementia. Copyright © 2006 John Wiley & Sons, Ltd.
Pores in synthetic nerve conduits are beneficial to regeneration
Authors: Vleggeert‐Lankamp C.L.A.M. , de Ruiter G.C.W. , Wolfs J.F.C. , Pêgo A.P. , van den Berg R.J. , Feirabend H.K.P. , Malessy M.J.A. , Lakke E.A.J.F.
Published: November 2006

Current opinion holds that pores in synthetic nerve guides facilitate nerve regeneration. Solid factual support for this opinion, however, is absent; most of the relevant studies assessed only morphological parameters and results have been contradictory. To evaluate the effect of pores, the rat sciatic nerve was either autografted or grafted with nonporous, macroporous (10–230 μm), and microporous (1–10 μm) biodegradable ε‐caprolactone grafts. Twelve weeks later, the grafted nerves were resected, and the electrophysiological properties were determined in vitro. Subsequently midgraft‐level sections were inspected, and peroneal nerve sections were evaluated morphometrically. Finally, the gastrocnemic and tibial muscle morphometrical properties were quantified. The microporous nerve graft performed much better than the nonporous and macroporous grafts with respect to most parameters: it was bridged by a free floating bundle that contained myelinated nerve fibers, there were more nerve fibers present distal to the graft, the electrophysiological response rate was higher, and the decrease in muscle cross‐sectional area was markedly smaller. Hence, the present study demonstrates the beneficial effect of synthetic nerve guide pores on nerve regeneration, although with the caveat that not pores per se, but only small (1–10 μm) pores were effective. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Nerve growth factor‐immobilized polypyrrole: Bioactive electrically conducting polymer for enhanced neurite extension
Authors: Gomez Natalia , Schmidt Christine E.
Published: November 2006

Biomaterials that present multiple stimuli are attractive for a number of biomedical applications. In particular, electrical and biological cues are important factors to include in interfaces with neurons for applications such as nerve conduits and neural probes. Here, we report the combination of these two stimuli, by immobilizing nerve growth factor (NGF) on the surface of the electrically conducting polymer polypyrrole (PPy). NGF was immobilized using an intermediate linker provided by a layer of polyallylamine conjugated to an arylazido functional group. Upon exposure to UV light and activation of the azido groups, NGF was fixed to the substrate. Three different surface concentrations were obtained (0.21–0.98 ng/mm2) and similar levels of neurite extension were observed on immobilized NGF as with soluble NGF. Additionally, electrical stimulation experiments were conducted with the modified polymer and revealed a 50% increase in neurite outgrowth in PC12 cells compared to experiments without electrical stimulation. This novel modification of PPy provides both electrical and biological stimulation, by presenting tethered growth factors and only producing a small decrease in the material's properties (conductivity ∼10 S cm−1) when compared to other modification techniques (conductivity ∼10−3–10−6 S cm−1). © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
The existence of secondary orbital interactions
Authors: Wannere Chaitanya S. , Paul Ankan , Herges Rainer , Houk K. N. , Schaefer Henry F. , Von Ragué Schleyer Paul
Published: November 2006

B3LYP/6‐311+G** (and MP2/6‐311+G**) computations, performed for a series of Diels‐Alder (DA) reactions, confirm that the endo transition states (TS) and the related Cope‐TSs are favored energetically over the respective exo‐TSs. Likewise, the computed magnetic properties (nucleus‐independent chemical shifts and magnetic susceptibililties) of the endo‐ (as well as the Cope) TS's reveal their greater electron delocalization and greater aromaticity than the exo‐TS's. However, Woodward and Hoffmann's original example is an exception: their endo‐TS model, involving the DA reaction of a syn‐ with an anti‐butadiene (BD), actually is disfavored energetically over the corresponding exo‐TS; magnetic criteria also do not indicate the existence of SOI delocalization in either case. Instead, a strong energetic preference for endo‐TSs due to SOI is found when both BDs are in the syn conformations. This is in accord with Alder and Stein's rule of “maximum accumulation of double bonds:” both the dienophile and the diene should have syn conformations. Plots along the IRC's show that the magnetic properties typically are most strongly exalted close to the energetic TS. Because of SOI, all the points along the endo reaction coordinates are more diatropic than along the corresponding exo pathways. We find weak SOI effects to be operative in the endo‐TSs involved in the cycloadditions of cyclic alkenes, cyclopropene, aziridine, cyclobutene, and cyclopentene, with cyclopentadiene. While the endo‐TSs are only slightly lower in energy than the respective exo‐TSs, the magnetic properties of the endo‐TS's are significantly exalted over those for the exo‐TS's and the Natural Bond Orbitals indicate small stabilizing interactions between the methylene cycloalkene hydrogen orbitals (and lone pairs in case of aziridine) with π‐character and the diene π MOs. © 2006 Wiley Periodicals, Inc. J Comput Chem 2007
Interpersonal process and outcome in variants of cognitive–behavioral psychotherapy
Authors: Critchfield Kenneth L. , Henry William P. , Castonguay Louis G. , Borkovec Thomas D.
Published: November 2006

Early sessions from three variants of cognitive–behavioral therapy (CBT) were examined to replicate work done in psychodynamic‐interpersonal treatments linking interpersonal process to outcome (W. P. Henry, T. E. Schacht, & H. H. Strupp, 1986, 1990). Cases were available from a component study of CBT for generalized anxiety disorder (T. D. Borkovec, M. G. Newman, A. L. Pincus, & R. Lytle, 2002) and were selected to form good and poor outcome groups maintained through a 1‐year follow‐up. A third group was also examined that had initial positive outcomes and marked decline by follow‐up (n = 8 for each). Structural analysis of social behavior (SASB) was used to identify interpersonal behaviors. Contrary to the authors' expectation, SASB variables were not strong predictors of outcome, and lower levels of interpersonal hostility were found than was the case in previous work. Findings are discussed in light of differences observed between treatment variants and the role that manuals may have in standardizing some aspects of the therapeutic relationship. © 2006 Wiley Periodicals, Inc. J Clin Psychol 63: 31–51, 2007.
Relative impact of adverse events and screened symptoms of posttraumatic stress disorder and depression among active duty soldiers seeking mental health care
Authors: Gahm Gregory A. , Lucenko Barbara A. , Retzlaff Paul , Fukuda Seiya
Published: November 2006

Symptoms of depression and posttraumatic stress are among the most studied psychological difficulties among soldiers. Such symptoms have been linked to a history of adverse events among both civilians and combat veterans. There is a paucity of research on this topic that can be applied to an active duty clinical population. Intake screening data were reviewed for 1,626 soldiers presenting to an outpatient mental health clinic to identify variables, including history of potentially traumatic experiences, associated with screened symptoms of posttraumatic stress disorder (PTSD) and depression. Demographics such as age, gender, and military rank, as well as number of adverse childhood experiences were significant predictors of screened PTSD and depression. A history of deployment to a combat zone predicted screened PTSD, but not depression. The role of childhood abuse as a risk factor is discussed and highlighted in the etiology of symptoms for soldiers seeking mental health care. © 2007 Wiley Periodicals, Inc. J Clin Psychol 63: 199–211, 2007.
The efficacy of personal construct therapy: A comprehensive review
Authors: Holland Jason M. , Neimeyer Robert A. , Currier Joseph M. , Berman Jeffrey S.
Published: November 2006

Prior narrative and quantitative reviews have suggested that personal construct therapy (PCT) is an efficacious and viable form of treatment. However, these reviews failed to include all published, controlled PCT outcome studies and did not account for all measures of outcome. The present quantitative review, therefore, offers a comprehensive integration of the 22 published studies that compare PCT to a control group, examining its overall efficacy at posttest and follow‐up as well as its effects for different types of outcome measures. Overall, the efficacy of PCT was found to be somewhat weaker than that reported in previous reviews. It was also found that traditional self‐report and behavioral observation measures tended to yield larger effects compared to measures that focused on personal meanings and scored content supplied by the client. © 2006 Wiley Periodicals, Inc. J Clin Psychol 63: 93–107, 2007.
Static SIMS studies of the oxides and hydroxides of aluminium
Authors: Verdier S. , Metson J. B. , Dunlop H. M.
Published: November 2006

The degree of hydroxylation or hydration of aluminium surfaces has been examined by static secondary ion mass spectroscopy (SSIMS). The SSIMS spectra of a series of aluminium oxide, oxyhydroxide and hydroxide surfaces have been obtained using instruments in three configurations. Similarities were observed in both negative and positive secondary ions spectra. Even though a direct comparison of the relative intensities cannot be made from one instrument to the other, a similar ranking of the various aluminium hydroxylation states was observed. Several ranking methods are discussed, as well as the similarities and differences observed while using the three instruments. Similar secondary ions were detected whatever the degree of hydroxylation of the aluminium oxide. This argues in favour of the formation of fragments by the combination of individually sputtered atoms or clusters to form the more stable secondaries, rather than the kick‐off of ‘structure‐related’ clusters originating directly from the upper surface layer. Copyright © 2006 John Wiley & Sons, Ltd.
Theoretical and spectroscopic studies of 5‐aminoorotic acid and its new lanthanide(III) complexes
Authors: Kostova Irena , Peica Niculina , Kiefer Wolfgang
Published: November 2006

The complexes of cerium(III) and neodymium(III) were synthesized by reaction of the respective inorganic salts with 5‐aminoorotic acid (H4L) in amounts equal to the metal:ligand molar ratio of 1:3. The structures of the final complexes were determined by means of spectral (IR, Raman, 1H NMR and 13C NMR) and elemental analysis. Significant differences in the IR spectra of the complexes were observed as compared to the spectrum of the ligand. A comparative analysis of the Raman spectra of the complexes with that of the free H4L allowed a straightforward assignment of the vibrations of the ligand groups involved in coordination. The geometry of H4L was computed and optimized for the first time with the Gaussian03 program using the B3PW91/6‐311++G**, B3PW91/LANL2DZ, B3LYP/6‐311++G** and B3LYP/LANL2DZ methods. The experimental IR and Raman bands of the ligand were assigned to normal modes on the basis of DFT calculations. The vibrational analysis performed for the studied species, H4L and its complexes, helped to explain the vibrational behavior of the ligand vibrational modes sensitive to interaction with the lanthanides. The vibrational study gave evidence for the coordination mode of the ligand to lanthanide ions and was in agreement with the other theoretical prediction. Copyright © 2006 John Wiley & Sons, Ltd.
Nondestructive analysis of single rapeseeds by means of Raman spectroscopy
Authors: Reitzenstein Sebastian , Rösch Petra , Strehle Marion A. , Berg Dorothea , Baranska Malgorzata , Schulz Hartwig , Rudloff Eicke , Popp Jürgen
Published: November 2006

The value of different vegetable oils can be correlated with the content of polyunsaturated fatty acids, especially omega‐3‐fatty acids such as linolenic acid, because of their contribution to healthy nutrition. One expression for the degree of unsaturation is the iodine value normally measured with gas chromatography. The use of Raman spectroscopy allows a rapid calculation of the iodine value and, in addition, only in a minimal sample volume. Therefore, this method can be used in single rapeseeds in order to predict the iodine value before harvesting. Additionally, the method can also be used for breeding investigations. Here, the lipid content and composition of a plant can be predicted by measuring the seedling without destruction. Copyright © 2006 John Wiley & Sons, Ltd.