bluuebunny/crossref_metadata_2025 huggingface dataset:
TECHNIQUES FOR VASCULARISED BONE GRAFTING IN SCAPHOID NONUNION
Authors: Wheen D. J. , Robinson M. , Prachaporn S. , Visvanathan S.
Published: May 2003

Nonunion of the scaphoid remains a significant problem in the management of scaphoid fractures. Recurrent persistent nonunion following attempts at internal fixation, and nonunions with sclerosis or avascular necrosis of the proximal pole of the scaphoid are particularly challenging. However, the aims of restoration of scaphoid anatomy and the achievement of union of the scaphoid remain the foundation pillars of scaphoid treatment. In recent years, several techniques for using vascularised bone grafts in the treatment of these difficult problems have been described. This article will review the currently described treatments, provide an overview of our unit experience with these techniques, and also describe a technique for in situ vascularisation of a conventional bone graft.
SEVERE CONTRACTURES OF THE PROXIMAL INTERPHALANGEAL JOINT IN DUPUYTREN'S DISEASE: VALUE OF CAPSULOLIGAMENTOUS RELEASE
Authors: Beyermann Kirsten , Jacobs Corinna , Lanz Ulrich
Published: May 2003

A retrospective review of severe flexion contractures (60° or more), involving 51 proximal interphalangeal joints in 40 patients with Dupuytren's disease, was performed. Thirty-two joints underwent aponeurectomy alone, 19 joints additional capsuloligamentous release. Mean follow-up was 12 months. No statistically significant difference was seen in the percentage of contracture correction in the capsulotomy group compared with the noncapsulotomy group.
CLINICAL UTILISATION OF COMPUTED TOMOGRAPHY OF THE SCAPHOID
Authors: Bain Gregory I.
Published: May 2003

Computed tomography is the best imaging modality to assess bony architecture. Scanning in the longitudinal plane of the scaphoid provides a greater appreciation of the humpback deformity. CT scan provides superior assessment of union and has a higher correlation with operative findings. A limitation of CT scanning is partial volume averaging which may give a false impression of a partial union when a nonunion exists. Height-to-length ratio provides superior observer variability for the assesssment of the humpback deformity. CT is useful to be able to "template" the proposed surgery of the scaphoid. It allows the surgeon to determine whether a structural bone graft is required, the preferred screw fixation and whether a volar or dorsal approach is required.
SOME COMBINATORIAL PROPERTIES OF MIXED CHORDAL RINGS
Authors: CHEN S. K. , HWANG F. K. , LIU Y. C.
Published: May 2003

We propose a new network called the mixed chordal ring where the amount of hardware and its structure are very comparable to the (directed) double-loop network, and yet can achieve a better diameter. We also investigated other combinatorial properties such as connectivity and hamiltonian circuits in the mixed chordal ring.
IMPROVED BOUNDS FOR THE CROSSING NUMBER OF THE MESH OF TREES
Authors: CIMIKOWSKI ROBERT , VRT'O IMRICH
Published: May 2003

Improved bounds for the crossing number of the mesh of trees graph, Mn, are derived. In particular, we derive a new lower bound of [Formula: see text] which improves on the previous bound of Leighton [11] by a constant factor, and an upper bound of [Formula: see text]. In addition, we construct drawings of Mn which achieve the upper bound number of crossings. We also prove that the crossing number of M4 is 4.
MESSY BROADCASTING IN MULTIDIMENSIONAL DIRECTED TORI
Authors: COMELLAS FRANCESC , HARUTYUNYAN HOVHANNES A. , LIESTMAN ARTHUR L.
Published: May 2003

In classical broadcast models, once a vertex receives the broadcast message, it sends the message out in such a way as to achieve the minimum possible broadcasting time. It is assumed either that there is a leader who coordinates the actions of all vertices during the broadcasting process, or that the vertices have a coordinated set of protocols which allow them to achieve minimum time broadcast for any originator. In the messy broadcast model, there is no leader, the vertices of the network do not know the starting time of the broadcast or the originator, the state of the whole scheme is unknown to any vertex, and the protocols are not coordinated. This model also describes a network with vertices that have small memories insufficient to store a set of coordinated protocols.

In this paper, we continue the study of messy broadcasting and present the first results for directed graphs. We obtain exact values for and bounds on the messy broadcast times of multidimensional directed tori.
A COMPACT LAYOUT OF THE BUTTERFLY
Authors: DINITZ YEFIM , EVEN SHIMON , ZAPOLOTSKY MARIA
Published: May 2003

For the Butterfly of N input/output vertices we present a layout on the rectilinear (square) grid of area ½N2 + o(N2). A lower bound of the same order is proved. The encompassing rectangle which defines the area is 45° slanted w.r.t. the grid axes and the input/output vertices are not on the boundary of this rectangle.

The layout is component-scalable, i.e., if one allocates for each switch a square of a × a area, the layout remains of area ½N2 + o(N2); that is, the value of a affects only the o(N2) term. The layout is also free of knock-knees.
MODELS OF DISTRIBUTED-SHARED-MEMORY ON AN INTERCONNECTION NETWORK FOR BROADCAST COMMUNICATION
Authors: KATSINIS CONSTANTINE
Published: May 2003

Due to advances in fiber-optics and VLSI technology, interconnection networks which allow multiple simultaneous broadcasts are becoming feasible. This paper examines the performance of distributed-shared-memory (DSM) systems based on the Simultaneous Optical Multiprocessor Exchange Bus (SOME-Bus) using queuing network models and develops theoretical results which predict processor utilization, message latency and other useful measures. It also presents simulation results which compare the performance of the SOME-Bus, the mesh and the torus using queuing-network models. The SOME-Bus is a low-latency, high-bandwidth, fiber-optic interconnection network which directly links arbitrary pairs of processor nodes without contention, and can efficiently interconnect over one hundred nodes. It contains a dedicated channel for the data output of each node, eliminating the need for global arbitration and providing bandwidth that scales directly with the number of nodes in the system. Each of the N nodes has an array of receivers, with one receiver dedicated to each node output channel. No node is ever blocked from transmitting by another transmitter or due to contention for shared switching logic. The entire N-receiver array can be integrated on a single chip at a comparatively minor cost resulting in o(N) complexity. The SOME-Bus has much more functionality than a crossbar by supporting multiple simultaneous broadcasts of messages, allowing cache consistency protocols to complete much faster. The effect of collective communications due to cache coherence is examined. Results reveal that the performance of the SOME-Bus interconnection network is the least affected by large communication times, compared to the other two architectures considered here. Even in the presence of intense coherence traffic, processor utilization and message latency is much less affected than in the other architectures.
AN OPTIMAL NEIGHBOURHOOD BROADCASTING SCHEME FOR STAR INTERCONNECTION NETWORKS
Authors: MKWAWA I. M. , KOUVATSOS D. D.
Published: May 2003

A novel and efficient neighbourhood broadcasting scheme is proposed for star interconnection networks, based on binomial trees and graph theoretic concepts. The optimal scheme has an upper bound of 1.33⌈log2(n - 2)⌉ + O(1) time steps and it is applicable to both single-port and half-duplex modes of message passing communication.
STRONG FAULT-TOLERANCE: PARALLEL ROUTING IN STAR NETWORKS WITH FAULTS
Authors: OH EUNSEUK , CHEN JIANER
Published: May 2003

We study the strong fault-tolerance for the star networks. Let G be a network in which all nodes have degree d. We say that G is strongly fault-tolerant if it has the following property: let Gf be a copy of G with at most d - 2 faulty nodes removed, then for any pair of non-faulty nodes u and v in Gf, there is a container of width t between u and v, where t is the minimum of degree of u and degree of v in Gf. We show that the star networks are strongly fault-tolerant and develop an algorithm that constructs a maximum width container of nearly optimal length in a star network with faults. Our algorithm requires no prior knowledge for the faulty nodes and runs in optimal time.
INFINITE COGALOIS THEORY, CLIFFORD EXTENSIONS, AND HOPF ALGEBRAS
Authors: ALBU TOMA
Published: May 2003

The aim of this paper is to present some connections of infinite Cogalois Theory with Clifford extensions and Hopf algebras.
ON THE POSET OF NON-TRIVIAL PROPER SUBGROUPS OF A FINITE GROUP
Authors: LUCIDO MARIA SILVIA
Published: May 2003

In this paper we describe the connected components of ℒ(G), the partially ordered set of non-trivial proper subgroups of a finite group G. This result is related to the study of the simple connectivity of the coset poset of a finite group.
ON THE COMPOSITION OF THE BURAU REPRESENTATION AND THE NATURAL MAP Bn → Bnk
Authors: ABDULRAHIM MOHAMMAD N.
Published: May 2003

A lot of linear representations of the braid group, Bn, arise as a result of treating braids as automorphisms of a free group. In this paper, we consider the composition of F. R. Cohen's map Bn → Bnk and the embedding Bnk → Aut (Fnk). This gives us a linear representation of Bn whose composition factors are one copy of the Burau representation and k - 1 copies of the standard representation, a representation investigated by I. Sysoeva.
IMPLICITIZATION OF SURFACES IN ℙ3 IN THE PRESENCE OF BASE POINTS
Authors: BUSÉ LAURENT , COX DAVID , D'ANDREA CARLOS
Published: May 2003

We show that the method of moving quadrics for implicitizing surfaces in ℙ3 applies in certain cases where base points are present. However, if the ideal defined by the parametrization is saturated, then this method rarely applies. Instead, we show that when the base points are a local complete intersection, the implicit equation can be computed as the resultant of the first syzygies.
LEFSCHETZ PRINCIPLE APPLIED TO SYMBOLIC POWERS
Authors: SCHOUTENS HANS
Published: May 2003

In this paper, an alternative proof is presented of the following result on symbolic powers due to Ein, Lazarsfeld and Smith [3] (for the affine case over [Formula: see text]) and to Hochster and Huneke [4] (for the general case). Let A be a regular ring containing a field K. Let [Formula: see text] be a radical ideal of A and let h be the maximum of the heights of its minimal primes. Then for all n, we have an inclusion [Formula: see text], where the first ideal denotes the hnth symbolic power of [Formula: see text]. In prime characteristic, this result admits an easy tight closure proof due to Hochster and Huneke. In this paper, the characteristic zero version is obtained from this by an application of the Lefschetz Principle.
A UNIPOTENT GROUP ACTION ON A FLAG MANIFOLD AND "GAP SEQUENCES" OF PERMUTATIONS
Authors: SHIPMAN BARBARA A.
Published: May 2003

There is a unipotent subgroup of Sl(n, C) whose action on the flag manifold of Sl(n, C) completes the flows of the complex Kostant–Toda lattice (a Hamiltonian system in Lax form) through initial conditions where all the eigenvalues coincide. The action preserves the Bruhat cells, which are in one-to-one correspondence with the elements of the permutation group Σn. A generic orbit in a given cell is homeomorphic to Cm, where m is determined by the "gap sequence" of the permutation, which lists the number inversions of each degree.
PROFINITE IDENTITIES FOR FINITE SEMIGROUPS WHOSE SUBGROUPS BELONG TO A GIVEN PSEUDOVARIETY
Authors: ALMEIDA J. , VOLKOV M. V.
Published: May 2003

We introduce a series of new polynomially computable implicit operations on the class of all finite semigroups. These new operations enable us to construct a finite pro-identity basis for the pseudovariety [Formula: see text] of all finite semigroups whose subgroups belong to a given finitely based pseudovariety H of finite groups.
Estimation of Entropy and Mutual Information
Authors: Paninski Liam
Published: May 2003

We present some new results on the nonparametric estimation of entropy and mutual information. First, we use an exact local expansion of the entropy function to prove almost sure consistency and central limit theorems for three of the most commonly used discretized information estimators. The setup is related to Grenander's method of sieves and places no assumptions on the underlying probability measure generating the data. Second, we prove a converse to these consistency theorems, demonstrating that a misapplication of the most common estimation techniques leads to an arbitrarily poor estimate of the true information, even given unlimited data. This “inconsistency” theorem leads to an analytical approximation of the bias, valid in surprisingly small sample regimes and more accurate than the usual [Formula: see text] formula of Miller and Madow over a large region of parameter space. The two most practical implications of these results are negative: (1) information estimates in a certain data regime are likely contaminated by bias, even if “bias-corrected” estimators are used, and (2) confidence intervals calculated by standard techniques drastically underestimate the error of the most common estimation methods.

Finally, we note a very useful connection between the bias of entropy estimators and a certain polynomial approximation problem. By casting bias calculation problems in this approximation theory framework, we obtain the best possible generalization of known asymptotic bias results. More interesting, this framework leads to an estimator with some nice properties: the estimator comes equipped with rigorous bounds on the maximum error over all possible underlying probability distributions, and this maximum error turns out to be surprisingly small. We demonstrate the application of this new estimator on both real and simulated data.
Ergodicity of Spike Trains: When Does Trial Averaging Make Sense?
Authors: Masuda Naoki , Aihara Kazuyuki
Published: May 2003

Neuronal information processing is often studied on the basis of spiking patterns. The relevant statistics such as firing rates calculated with the peri-stimulus time histogram are obtained by averaging spiking patterns over many experimental runs. However, animals should respond to one experimental stimulation in real situations, and what is available to the brain is not the trial statistics but the population statistics. Consequently, physiological ergodicity, namely, the consistency between trial averaging and population averaging, is implicitly assumed in the data analyses, although it does not trivially hold true. In this letter, we investigate how characteristics of noisy neural network models, such as single neuron properties, external stimuli, and synaptic inputs, affect the statistics of firing patterns. In particular, we show that how high membrane potential sensitivity to input fluctuations, inability of neurons to remember past inputs, external stimuli with large variability and temporally separated peaks, and relatively few contributions of synaptic inputs result in spike trains that are reproducible over many trials. The reproducibility of spike trains and synchronous firing are contrasted and related to the ergodicity issue. Several numerical calculations with neural network examples are carried out to support the theoretical results.
Leave-One-Out Bounds for Kernel Methods
Authors: Zhang Tong
Published: May 2003

In this article, we study leave-one-out style cross-validation bounds for kernel methods. The essential element in our analysis is a bound on the parameter estimation stability for regularized kernel formulations. Using this result, we derive bounds on expected leave-one-out cross-validation errors, which lead to expected generalization bounds for various kernel algorithms. In addition, we also obtain variance bounds for leave-oneout errors. We apply our analysis to some classification and regression problems and compare them with previous results.
Reducing the Time Complexity of the Derandomized Evolution Strategy with Covariance Matrix Adaptation (CMA-ES)
Authors: Hansen Nikolaus , Müller Sibylle D. , Koumoutsakos Petros
Published: May 2003

This paper presents a novel evolutionary optimization strategy based on the derandomized evolution strategy with covariance matrix adaptation (CMA-ES). This new approach is intended to reduce the number of generations required for convergence to the optimum. Reducing the number of generations, i.e., the time complexity of the algorithm, is important if a large population size is desired: (1) to reduce the effect of noise; (2) to improve global search properties; and (3) to implement the algorithm on (highly) parallel machines. Our method results in a highly parallel algorithm which scales favorably with large numbers of processors. This is accomplished by efficiently incorporating the available information from a large population, thus significantly reducing the number of generations needed to adapt the covariance matrix. The original version of the CMA-ES was designed to reliably adapt the covariance matrix in small populations but it cannot exploit large populations efficiently. Our modifications scale up the efficiency to population sizes of up to 10n, where n is the problem dimension. This method has been applied to a large number of test problems, demonstrating that in many cases the CMA-ES can be advanced from quadratic to linear time complexity.
Qualms Regarding the Optimality of Cumulative Path Length Control in CSA/CMA-Evolution Strategies
Authors: Beyer Hans-Georg , Arnold Dirk V.
Published: May 2003

Cumulative step-size adaptation (CSA) based on path length control is regarded as a robust alternative to the standard mutative self-adaptation technique in evolution strategies (ES), guaranteeing an almost optimal control of the mutation operator. This paper shows that the underlying basic assumption in CSA — the perpendicularity of expected consecutive steps — does not necessarily guarantee optimal progress performance for (μ/μIλ) intermediate recombinative ES
General Schema Theory for Genetic Programming with Subtree-Swapping Crossover: Part I
Authors: Poli Riccardo , McPhee Nicholas Freitag
Published: May 2003

This is the first part of a two-part paper which introduces a general schema theory for genetic programming (GP) with subtree-swapping crossover. The theory is based on a Cartesian node reference system which makes it possible to describe programs as functions over the space N2 and allows one to model the process of selection of the crossover points of subtree-swapping crossovers as a probability distribution over N4. In Part I, we present these notions and models and show how they can be used to calculate useful quantities. In Part II we will show how this machinery, when integrated with other definitions, such as that of variable-arity hyperschema, can be used to construct a general and exact schema theory for the most commonly used types of GP
Modification Point Depth and Genome Growth in Genetic Programming
Authors: Luke Sean
Published: May 2003

The evolutionary computation community has shown increasing interest in arbitrary-length representations, particularly in the field of genetic programming. A serious stumbling block to the scalability of such representations has been bloat: uncontrolled genome growth during an evolutionary run. Bloat appears across the evolutionary computation spectrum, but genetic programming has given it by far the most attention. Most genetic programming models explain this phenomenon as a result of the growth of introns, areas in an individual which serve no functional purpose. This paper presents evidence which directly contradicts intron theories as applied to tree-based genetic programming. The paper then uses data drawn from this evidence to propose a new model of genome growth. In this model, bloat in genetic programming is a function of the mean depth of the modification (crossover or mutation) point. Points far from the root are correspondingly less likely to hurt the child's survivability in the next generation. The modification point is in turn strongly correlated to average parent tree size and to removed subtree size, both of which are directly linked to the size of the resulting child.
Partner choice in piranha shoals
Authors: Magurran Anne , Queiroz Helder
Published: May 2003

Although the red-bellied piranha, Pygocentrus nattereri is widely portrayed as a pack-hunting predator virtually nothing is known about its shoaling behaviour. Using fish collected in the flooded forest of the Brazilian Amazon, we conducted a range of choice tests to determine whether individual piranhas make non-random shoaling decisions. These revealed that partner size had a significant impact on shoaling preferences. Piranha shoals were size structured with large, sexually mature, individuals occupying the central zone (defined as within the polygon connecting fish at the edge of the shoal). Small, non-reproductive individuals showed greater motivation to feed. Fish did not discriminate between size-matched individuals from the same and different locality and we found no evidence of intraspecific aggression, despite the piranha's reputation for cannibalism.
Ejaculate size variation in the migratory locust, Locusta migratoria
Authors: Arlt Debora , Reinhardt Klaus
Published: May 2003

Sperm competition models suggest that ejaculate size (ES) is adjusted in relation to female fecundity and the risk of sperm competition, depending on the information males have about that risk. We tested these ideas in the migratory locust, Locusta migratoria, a species in which ES may be an important male fitness parameter. Copulation duration was positively correlated with ES. Males did not increase copulation duration but sperm transfer in the presence of competitors during mating. They did so only when they were reared in conditions that allowed female perception prior to mating. Males that prior to mating were kept with other males only did not show ES variation with regard to different sex ratios at mating. Increased female availability did not affect ES. A male size and condition related parameter was not significantly correlated to ES but older males delivered smaller ejaculates. Females of larger size were inseminated larger amounts of sperm. There was a positive correlation between female size and ES only for males of lower condition and lower relative testis weight but not for males of good condition or higher relative testis weight.
African wild dog pup vocalizations with special reference to Morton's model
Authors: Robbins Robert , McCreery E. Kim
Published: May 2003

African wild dog (Lycaon pictus) pup vocalizations were studied in Hwange National Park, Zimbabwe for weeks 3 through 7 of the socialization period. Here we present the vocal repertoire, including the use of repetitive and mixed sounds, and investigate the extent to which the emerging sound system of Lycaon conforms to predicted design features of Morton's (MS) motivation-structural rules. Features of the pup sound system are highlighted by comparison with adults and other social canids. Data were collected at three den sites (litter sizes: 8, 8, and 9) of two study packs. A total of 1903 vocalizations were classified, and eight vocal classes and seven subclasses were identified. Although all sounds identified persist into adulthood, observations indicate a delayed onset in some vocal classes, including both the lowest (i.e. rumbles) and highest (i.e. twitters) frequency sounds. As predicted by the (MS) model, pups invested heavily in high frequency, harmonic care/social soliciting sounds (91%, N = 1586 unmixed vocalizations), however, no clear association between acoustic structure and sound repetition was found. Significantly more repetition was heard in all vocal classes with the exception of moans and barks. Intra-pack aggression is generally muted in this obligate social carnivore suggesting that repetition may be a low cost strategy to induce social outcomes and obtain food. The patterning of mixed vocalizations (N = 317) was consistent with the (MS) model. Given the high degree of cooperation necessary for individual survival, the predominant use of cross-mixed sounds may serve to minimize conflict as pups begin to form relationships with littermates and adults. Noisy/noisy sounds were exceptionally rare. Comparative data suggest a relationship between the early patterning of mixed sounds and species-specific social organization in canids.
Dynamic changes in alarm call structure: a strategy for reducing conspicuousness to avian predators?
Authors: Evans Christopher , Bayly Karen
Published: May 2003

The design of many animal signals reflects the need to maximize signal efficacy while minimizing conspicuousness to eavesdroppers. The aerial alarm calls of birds have been a useful model system for exploring such evolutionary tradeoffs at the level of general call structure, but much less is known about changes in fine-scale signal characteristics over the course of an encounter with a potential predator. We analyzed variation in the alarm calls that male fowl, Gallus gallus, produced in response to raptor silhouettes moving overhead. Spectrogram cross-correlation was used to test for changes in structure over the course of a call bout. This analysis revealed that aerial alarm calls are individually distinctive and that they vary significantly from the first call to the second. We then measured single acoustic parameters, including the duration, dominant frequency and frequency bandwidth of each component in successive calls. Males almost invariably began the first call in a bout with a high amplitude broad-band pulse, which was followed by a much longer and highly variable sustained element. They then selectively reduced or eliminated the introductory pulse, while leaving other aspects of alarm structure unchanged. Recent work has shown that the introductory pulse is potentially costly because it has attributes that are readily localized by raptors. We suggest that male fowl have adaptive plasticity in alarm call structure, allowing them to manage short-term predation risk while continuing to signal to companions.
Mixed-species associations of Diana and Campbell's monkeys: the costs and benefits of a forest phenomenon
Authors: Wolters Sonja , Zuberbühler Klaus
Published: May 2003

One of the most striking behavioural patterns of many forest primates concerns their tendency to live in semi-permanent mixed-species groups. Functional investigations have ascertained that individuals obtain some antipredator benefits without paying the costs of intra-species resource competition. Despite these advances, very little is known about the subtle mechanisms that keep mixed species groups together on a daily basis. Our results showed that in the Diana-Campbell's monkey association both species benefited from each other in diverse and idiosyncratic ways. In the presence of Campbell's monkeys the conspicuous Diana monkeys were more likely to descend into the lower forest strata, increased their foraging behaviour, and individuals became less vigilant. The cryptic Campbell's monkeys, in turn, were able to use the higher forest strata and exposed areas more often, spread out over larger areas, were more likely to travel, and engaged in more conspicuous vocal behaviour when associated with Diana monkeys. These data suggested that both species benefited from each other in ways that went beyond passive group-size related antipredator benefits, such as a dilution effect and increased chances of predator detection. Instead, the increased safety of the mixed species group allowed individuals to exploit their ecological niche more broadly, to forage more efficiently, and to engage in more social behaviour, suggesting that the benefits of mixed species groups are much more varied and diverse than currently thought.
The Diversity of Class Analyses: A Critique of Erik Olin Wright and Beyond
Authors: Resnick Stephen , Wolff Richard
Published: May 2003

Class analyses are both very old and quite new. This essay argues that Marx contributed a new class definition and analysis focused on the production, appropriation, and distribution of surplus labor. Yet, that innovative, new class analysis was lost by being dissolved into either pre-Marxian conceptualizations of class in terms of property and power or later social theories in which class was determined by people's consciousness and self-identifications. In this context, the essay pays special attention to the recent work of E.O. Wright. Class analysis based on the surplus labor definition of class is compared and contrasted with Wright's differently based definition and analysis.
Racism and Capitalist Accumulation: An Overdetermined Nexus
Authors: Gabriel Satyananda J. , Todorova Evgenia O.
Published: May 2003

This paper explores the nexus connecting the social construction of racialized consciousness to capitalist exploitation and the related process of capitalist accumulation. Racism partly constitutes and ceaselessly alters capitalist exploitation and accumulation and vice versa. Struggles to end racism are argued to be distinct from struggle to end capitalist exploitation. Depending on their social conditions, the two kinds of struggles may support or conflict with one another. The paper concludes that racism and capitalist exploitation must be understood as distinct social processes, shaping each other in complex and contradictory ways.
Class Transformation in the Household: An Opportunity and a Threat
Authors: Fraad Harriet
Published: May 2003

The intimate relationships of contemporary life — household, marriage, family — have rarely been examined in terms of the class processes (in surplus labor terms) that they include. This essay explores the class processes that shape household relationships today. It examines the interactions between class and non-class processes — especially the gender processes that likewise constitute those intimate relationships. A major goal is to specify how the interactions of class and non-class processes contribute to the contemporary “crisis” of the family. A second goal is to consider what combination of class and non-class transformations might resolve that crisis.
Electrochemical Polishing of Copper for Microelectronic Applications
Authors: Huo J. , Solanki R. , McAndrew J.
Published: May 2003

Electrochemical polishing (ECP) of copper using hydroxyethylidenediphosphonic acid (HEDP) has been investigated as an alternative to chemical mechanical polishing (CMP) for integration of low-k dialectrics in microelectronic devices. An optimal copper ECP process produces smooth polishing and a fast removal rate. For this investigation copper anodic polarisation curves in HEDP-phosphoric acid solutions were measured and copper ECP effects in various HEDP-phosphoric acid solutions were examined. Copper surface smoothing effects in various HEDP-phosphoric acid solutions were evaluated with atomic force microscopy. It was shown that HEDP and HEDP-phosphoric acid solutions have polarisation curves with a limited current plateau characteristic of ECP. Twenty to forty per cent of HEDP solutions had a maximum limiting current density of ∼80 A cm-2. Adding phosphoric acid to HEDP solutions increased the limiting current to a maximum, beyond which further addition caused a decrease. An optimal ECP effect (removal rate = 1.8 μm min-1, 80% reduction in mean roughness) was achieved with a solution of 30HEDP + 30H3PO4 + 40H2O (vol.-%). A higher removal rate was achieved by decreasing the concentration of phosphoric acid, but this resulted in a reduction of the smoothing effect.
High Temperature Oxidation and Corrosion Resistant Nanocrystalline Coatings
Authors: Wang F. , Geng S.
Published: May 2003

Traditional high temperature oxidation resistant coatings are divided into three types: aluminide or modified aluminide coatings such as Cr-Al, Si-Al and Pt-Al; MCrAlY(M = Fe,Co and/or Ni) overlayer coatings and MCrAlY + Y2O3/ZrO2 thermal barrier coatings. Characteristic of these coatings is that their compositions are very different from their substrate alloys. Protection comes from the higher aluminium content in the coating to form Al2O3 at high temperature. However, these coatings may be harmful to the mechanical properties of the alloys as a result of the interdiffusion or thermal mismatch between the coating and substrate. Recently, a new kind of coating has been developed: high temperature oxidation resistant and hot corrosion resistant nanocrystalline coating, the composition of which is the same as the substrate. The only difference is that the grain size of the coating is several orders of magnitude smaller than that of the substrate. The formation of protective Al2O3 scale is not from the high aluminium content, but from the grain boundary diffusion. The main advantages of this kind of coating are that neither interdiffusion nor thermal mismatch exist between coating and substrate. The present paper reviews the high temperature oxidation and hot corrosion resistant nanocrystalline coating with particular reference to the authors’ own results.
Deposition of BaxSr1-xTiO3 in Atmospheric Pressure Flame: Combustion Monitoring and Optimisation of Thin Film Properties
Authors: Oljaca M. , Luten H. A. , Tomov T. , Sundell S. , Hunt A.
Published: May 2003

An atmospheric pressure spray flame was used to deposit barium-strontium-titanate (BaxSr1-xTiO3, BST) films by the combustion chemical vapour deposition (CCVD) process. CCVD flames with and without substrate were analysed as a function of spray droplet size and substrate deposition location. Emission spectroscopy and temperature pyrometry measurements were used to determine flame structure and temperature. Emissions from atomic and molecular species reach a maximum early in the flame zone and then decrease sharply, an observation indicative of very fast reaction rates. The spray droplet size has a marked effect on the surface morphology of deposited thin films: coarser sprays yield a rougher film surface while finer sprays produce a smooth, optically clear surface. Optimal conditions for the deposition of high performance ferroelectric BST films had a mean droplet size of 1-2 μm and deposition temperature between 1000 and 1100 °C. BST films deposited under optimised conditions on single crystal substrates were of the desired phase and showed a high degree of in plane orientation.
Surface Modification of Diamond Film Adsorbents for Blood Plasma Cleaning
Authors: Bogatyreva G. P. , Marinich M. A.
Published: May 2003

Synthetic diamond presents a new class of carbon containing adsorbents. Diamond is an efficient adsorbent of blood plasma toxins of organic and inorganic origins. Thermal or electrochemical modification of the diamond surface substantially increases its ability to adsorb. Diamond adsorbents are characterised by a selective adsorption mechanism: a hydrophobic surface adsorbs mainly cations of heavy metals and a hydrophilic surface absorbs organic molecules.
Process Developments towards Producing Well Adherent Duplex PAPVD Coatings
Authors: Batista J. C. A. , Godoy C. , Matthews A. , Leyland A.
Published: May 2003

Duplex treatments consisting of a plasma nitrided layer followed by a PAPVD hard coating have gained attention in recent years. However, obtaining a satisfactory adhesion strength between the PAPVD hard coatings and the nitrided layers is a key issue in duplex coating processing, especially if plasma nitriding and coating deposition processes are to be carried out sequentially in a PAPVD plant. Inadequate process control will lead to the formation of a soft ‘black layer’ below the coating by thermochemical decomposition of the compound layer, which adversely affects the load bearing capacity of the composite and, consequently, the adhesion between the hard coating and the nitrided subsurface. In the present paper an intermediate treatment which allows the production of duplex TiN coatings with good adhesion is described, even if a compound layer is formed during plasma nitriding. This intermediate treatment also provides a way to produce duplex coatings in which the nitrided subsurface is compound layer free. Moreover, scratch and impact test results indicate that a monophase ϵ compound layer does not have any detrimental effects on the adhesion and impact resistance of duplex TiN coatings. Similar levels of adhesion strength were recorded for duplex TiN coatings with nitrided layers consisting of either a monophase ϵ compound layer + diffusion zone or a diffusion zone only; however, in impact tests, it was found that the former outperformed the latter. Such results indicate that it is feasible to produce well adherent duplex coatings with monophase compound layers if process parameters are carefully controlled in order to avoid compound layer destabilisation.
Influence of Bias Voltage on Copper Nitride Films Deposited by Reactive Sputtering
Authors: Pierson J. F.
Published: May 2003

This paper investigates the effect of negative bias voltage applied to substrates on the structure and electrical resistivity of films deposited with rf sputtering on a copper target in reactive Ar-N2 mixtures. To show the influence of the nitrogen content in the film, four different nitrogen flow rates have been chosen from the results of a previous study. Whatever the nitrogen flow rate when a negative bias voltage is applied to the substrates, copper diffraction peaks are detected. This is due to nitrogen resputtering during the film growth. This resputtering phenomenon can be so significant that films deposited with a low nitrogen flow rate and high bias voltage are composed only of copper. With other deposition conditions, the films are biphased: Cu + Cu3N. In these films, the Cu3N crystal orientation is also dependent on the bias voltage. Since the nitrogen content of the films evolves and since copper crystals are formed, the electrical resistivity of the films decreases when a bias voltage is applied. However, the electrical resistivity of biphased coatings does not reach that of copper and therefore, copper grains do not percolate in these films.
Oxidation Behaviour of Kanthal APM and Kanthal AF at 1173 K: Effect of Yttrium Alloying Addition
Authors: Cueff R. , Buscail H. , Caudron E. , Issartel C. , Riffard F.
Published: May 2003

The oxidation behaviour of two commercial FeCrAl alloys, Kanthal APM (produced by powder metallurgy) and Kanthal AF (produced by melting and containing alloying additions of yttrium), has been investigated during isothermal exposures in air at 1173 K. Mass gains were measured by thermogravimetry and identification of the oxidation products determined by in situ high temperature X-ray diffraction. The morphology of the oxide layer surfaces was studied by SEM, the elemental distribution inside the scales being carried out by EDXS analysis. After an initial transient stage, a diffusional process appears to predominantly control the oxidation kinetics of both alloys. During the transient stage, relatively important mass gains have been revealed, and the presence of yttrium does not seem to have a significant effect on the oxidation rate. In the parabolic oxidation stage however, yttrium showed a marked influence on the composition and growth rate of the oxide scale. The present study indicates that the reactive element drastically reduces the parabolic rate constant and promotes the transformation of transition alumina into α-Al2O3, which leads to the growth of a more protective oxide scale. It has also revealed that an enrichment of chromium (as chromium carbide precipitates) near the scale/metal interface occurred in the oxide layer formed on Kanthal APM.
Corrosion Properties of H Mode RF Inductively Coupled Plasma Nitrided Stainless Steel Substrates
Authors: Chakrabarty C. K.
Published: May 2003

The corrosion properties of nitrided stainless steel substrates processed in the H mode (plasma driven by an induced azimuthal electric field) of a low frequency rf inductively coupled plasma (ICP) source are investigated. The processing parameters were carefully selected considering the repeatability of the device. Nitrogen plasma operating in the H mode was used for the nitriding process and proper substrate bias was applied during nitriding. Several stainless steel substrates were nitrided at different processing times. Microhardness, XRD and EDX tests were performed on the nitrided samples prior to corrosion testing. The electrochemical polarisation method was used for the latter and the corrosion resistance properties were successfully characterised. Results show the correlation of nitriding times, the phases formed and surface hardness in an assessment of the corrosion properties of the samples.
COPD: problems in diagnosis and measurement
Authors: Weiss S.T. , DeMeo D.L. , Postma D.S.
Published: May 2003

Chronic obstructive pulmonary disease (COPD) is the most rapidly rising cause of death in individuals >65 yrs of age, the most rapidly growing segment of the USA population.

Advancing the clinical research agenda for COPD entails careful consideration of several issues and problems: defining COPD, reliance on physiological testing, outcome measurements and comorbidities.

In addition, issues pertaining to the recent dramatic increase in chronic obstructive pulmonary disease mortality in females, smoking susceptibility and the relationship of respiratory symptoms with hyperresponsiveness, as well as chronic obstructive pulmonary disease heterogeneity, are discussed.
Embodied rural geographies: Developing research agendas
Authors: Little Jo , Leyshon Michael
Published: May 2003

This paper responds to the scarcity of work on rural embodiment. We argue that a consideration of ‘the body’ can contribute significantly to an understanding of rural social relations and communities. In particular, this paper provides an additional critical dimension to the understanding of the relationship between changing femininities, masculinities, rurality and the performance of sexuality in rural areas. It shows how dominant constructions of rural masculinity and femininity incorporate highly traditional assumptions about the body and reflect conventional attitudes to sexuality and gender identity. This paper gathers together some partial and underdeveloped ideas and data in the production of a more coordinated and sustained consideration of embodiment and rurality, and details some emerging research directions.
Commodifying what nature?
Authors: Castree Noel
Published: May 2003

In this essay contemporary Marxist writings on the commodification of nature in capitalist societies are reviewed systematically. Recent research on commodities in human geography, cultural studies and related fields have been largely post or non-Marxist in tenor and have paid relatively little attention to the ‘natural’ dimensions of commodities. By contrast, recent Marxist writings about capitalism-nature relations have tried to highlight both the specificity of capitalist commodification and its effects on ecologies and bodies. This fact notwithstanding, it is argued that the explanatory and normative dimensions of this Marxist work are, respectively, at risk of being misunderstood and remain largely implicit. On the explanatory side, confusion arises because the words ‘commodification’ and ‘nature’ are used by different Marxists to refer to different things that deserve to be disentangled. On the normative side, the Marxian criticisms of nature's commodification are rarely explicit and often assumed to be self-evident. The essay offers a typology of commodification processes relating to specific natures with specific effects to which a variety of criticisms can be applied. Though essentially exegetical rather than reconstructive, the essay tries to pave the way for a more precise sense of how the commodification of nature in capitalist societies works and why it might be deemed to be problematic.
Islands of practice and the Marston/Brenner debate: toward a more synthetic critical human geography
Authors: Purcell Mark
Published: May 2003

This paper argues that an important obstacle to the continued development of critical human geography are ‘islands of practice’, through which scholars become embedded in a research and writing tradition that limits their intellectual and political horizons. I use a recent nondebate in Progress in Human Geography between Sallie Marston and Neil Brenner as an illustration of how islands of practice can stifle intellectual exchange. The paper suggests that the best way to dissolve the islands is a methodological program to create a more synthetic approach that consciously integrates multiple aspects of the critical project.
Ice-wedge casts as indicators of palaeotemperatures: precise proxy or wishful thinking?
Authors: Murton Julian B. , Kolstrup Else
Published: May 2003

The use of ice-wedge casts to reconstruct palaeotemperatures involves three stringent assumptions: (1) the influence of air temperature on ice-wedge cracking and the distribution of growing ice wedges are well known in contemporary permafrost environments; (2) contemporary and former permafrost environments are sufficiently similar for the same quantitative relationships between air temperature and ice-wedge cracking to apply to both environments; and (3) the history of ice-wedge growth and decay can confidently be inferred from ice-wedge casts. We propose that the validity of these assumptions has been overestimated in terms of the Weichselian of northwest Europe because of (i) limited knowledge of the frequency of ice-wedge cracking in contemporary permafrost environments; (ii) the complex and incompletely understood natural controls on cracking; (iii) probable differences between former cold environments in mid latitudes and contemporary cold environments in high latitudes; (iv) limited understanding of ice-wedge growth and decay histories, and of the natural controls on and mechanisms of ice-wedge casting; and (v) different time perspectives. Given all these uncertainties, it is timely to critically re-evaluate the use of Weichselian ice-wedge casts for palaeoclimatic and environmental reconstructions.
Predictive soil mapping: a review
Authors: Scull P. , Franklin J. , Chadwick O. A. , McArthur D.
Published: May 2003

Predictive soil mapping (PSM) can be defined as the development of a numerical or statistical model of the relationship among environmental variables and soil properties, which is then applied to a geographic data base to create a predictive map. PSM is made possible by geocomputational technologies developed over the past few decades. For example, advances in geographic information science, digital terrain modeling, remote sensing, fuzzy logic has created a tremendous potential for improvement in the way that soil maps are produced. The State Factor soil-forming model, which was introduced to the western world by one of the early Presidents of the American Association of Geographers (C.F. Marbut), forms the theoretical basis of PSM. PSM research is being driven by a need to understand the role soil plays in the biophysical and biogeochemical functioning of the planet. Much research has been published on the subject in the last 20 years (mostly outside of geographic journals) and methods have varied widely from statistical approaches (including geostatistics) to more complex methods, such as decision tree analysis, and expert systems. A geographic perspective is needed because of the inherently geographic nature of PSM.
Extracting biophysical parameters from remotely sensed radar data: a review of the water cloud model
Authors: Graham A. J. , Harris R.
Published: May 2003

The semi-empirical water cloud model can be implemented to derive spatial values of biophysical parameters from remotely sensed radar data for use throughout different disciplines of physical geography. The water cloud model formulation and development are detailed in this review paper, incorporating the major advances and publications related to the model.