bluuebunny/crossref_metadata_2025 huggingface dataset:
Updating routing tables after resource failure in a distributed computer network
Authors: Johnson Marjory J.
Published: May 2007

This paper is an analysis of overhead required by the MERIT routing table update algorithm after failure of a single network resource. The number of update messages sent by each node during the update process is used as the measure of update overhead. Both synchronous behavior and asynchronous behavior of the MERIT algorithm are considered. The number of messages required for synchronous update is shown to be an upper bound for the number of messages required if update occurs asynchronously. The effect of network topology on update overhead is discussed. Finally, some implementation suggestions aimed at minimizing looping of messages during routing table update are presented.
Hierarchical vehicle routing problems
Authors: Marchetti Spaccamela A. , Rinnooy Kan A. H. G. , Stougie L.
Published: May 2007

Hierarchical vehicle routing problems, in which the decision to acquire a number of vehicles has to be based on imperfect (probabilistic) information about the location of future customers, allow a natural formulation as two‐stage stochastic programming problems, where the objective is to minimize the sum of the acquisition cost and the length of the longest route assigned to any vehicle. For several versions of this difficult optimization problem, we show that simple heuristics have strong properties of asymptotically optimal behavior.
Properties of the k‐centra in a tree network
Authors: Andreatta G. , Mason F. M.
Published: May 2007

The k‐centrum of a graph G ‐ (V, E)is the set of vertices each minimizing the sum of the distances from it to the corresponding k farthest vertices of G. In this article properties of k‐centrum of trees, where edges have positive real lengths, are investigated.
Network reliability analysis using 2‐connected digraph reductions
Authors: Agrawal Avinash , Satyanarayana A.
Published: May 2007

The problem of computing the SKT reliability, the probability that a source s can send communication to a specified set of terminals K ⊂ V in a probabilistic digraph D = (V,E) is considered. For general digraphs, this problem is known to be NP‐hard and it is helpful to consider schemes that can decompose the problem into a number of smaller problems. A non‐separable digraph is 2‐connected if it contains a separation pair, a pair of nodes whose removal disconnects the digraph. Such a digraph can be partitioned into two or more segments. It is shown that at least one of these segments can be replaced by a simpler structure; this replacement results in an exact reliability preserving reduction. The proposed reduction scheme is general and is applicable to all digraphs containing a separation pair; earlier methods could only handle special cases. For a class of digraphs, called BSP digraphs, such a reduction is always admissible and the SKT reliability can be computed in time O(∣E∣). A digraph is a BSP digraph if its underlying undirected graph is series‐parallel. A BSP digraph can be cyclic or acyclic. No polynomial‐time algorithms were previously known for this class of digraphs.
Optimal consecutive‐2 systems of lines and cycles
Authors: Du D. Z. , Hwang F. K.
Published: May 2007

A consecutive‐2 system is a graph where each vertex can either work or fail and the system fails if and only if two vertices incident to the same edge both fail. The simplest probability structure attached to such systems is to assume that vertex i has probability pi of failing and the states of the vertices are stochastically independent. For a given graph G of n vertices and a given set P of n probabilities, an optimal consecutive‐2 system is the triple (G,P,M), where M is a mapping from P to the vertices of G such that the probability of the system failing is minimum. Consecutive‐2 systems have been widely studied when the graph is either a line or a cycle. In this paper we study optimal consecutive‐2 systems which consist of many lines or many cycles. Our results provide optimal mappings that depend only on the rankings of the individual failure probabilities and not on their actual values. Moreover, we show by examples that rankings alone are probably insufficient to solve cases more complex than those solved in this paper.
A heuristic circulation‐network approach to solve the multi‐traveling salesman problem
Authors: Garcia‐Diaz Alberto
Published: May 2007

The overall methodology developed in this paper can be organized into two major parts. The first part consists of a representation of the Multi‐Traveling Salesman Problem as a network circulation model. The second part is a subtour elimination procedure. The circulation‐network representation of the Multi‐Traveling Salesman Problem allows the generation of a starting solution which satisfies the optimality LP conditions of the network, but which may not be feasible in the context of the original problem due to the existence of subtours. The proposed network algorithm iteratively reduces the set of solutions with subtours by eliminating one link and then rerouting its flow, using the remaining arcs without violating their LP optimality conditions. Computational results based on a sample of 91 randomly generated problems are reported.
On a conjecture of trietsch and handler on the flow‐dependent steiner ratio
Authors: Du D. Z. , Hwang F. K.
Published: May 2007

Recently Trietsch and Handler extended a conjecture of Pollak and Gilbert on the Steiner ratio to a model first studied by Gilbert where the cost of an edge is flow dependent. For three given points Trietsch and Handler showed that the maximum Steiner ratio is achieved when the cost is independent of the flow, i. e., the extended conjecture is reduced to the original conjecture. They also conjectured that the two conjectures are equivalent for any number of given points. In this paper we give a counterexample to their conjecture if the number of given points is at least four. We also replace their proof for the three‐point case, which depends heavily on computer‐aided calculations, by a simple geometric proof.
The structure of distances in networks
Authors: Howe Eric , Johnson Charles R. , Lawrence James
Published: May 2007

Part of this work is concerned with determining those graphs that produce extreme rays of the cone of shortest distance matrices of undirected linear n‐vertex graphs without loops. For n ≤ 4, for example, all extreme rays come from a certain class of “elementary” graphs, but for n ≥ 5 there are nonelementary extreme rays, and these are studied further. Another part of this work is concerned with the representation of a distance matrix as a set of distances among points in a normed vector space. The set of graphs (distance matrices) representable by a given norm and the set of norms (and dimensions of spaces) by which a given graph may be represented are studied. It is shown that lx is unique among lp norms in that any graph is lx representable in Rn−1. The l1 representable distance matrices are found to be just those in the cone generated by elementaries for all n. Other results on distance matrices are also included.
Reliable broadcast protocols in unreliable networks
Authors: Awerbuch Baruch , Event Shilmon
Published: May 2007

Broadcast is the task of delivering copies of a packet to all nodes in a communication network. A broadcast is called reliable if all the packets are accepted by all the nodes in finite time and in the correct order. This paper presents a class of reliable broadcast protocols for unreliable networks. One of these protocols achieves reliable broadcast with minimum broadcast cost, assuming that the network allows reliable broadcast at all. In case that the network's topology is stable, the minimum broadcast delay is achieved. No existing broadcast protocol achieves this goal. As a by‐product, we achieve a new reliable routing protocol.
New lower planes for the network design problem
Authors: Ahuja R. K. , Murty V. V. S.
Published: May 2007

A lower plane for the network design problem is a linear lower approximation of the objective function and is used to obtain a lower bound in the branch and bound algorithm. In this article, we derive two new lower planes for the network design problems through combinatorial arguments. The first lower plane is of complexity O(n4) and produces a lower bound which is sharper than those of existing lower planes. The second lower plane is of complexity O(n3) and produces a reasonably good lower bound. Computational results are presented comparing the bounds obtained by the new lower planes with those of the existing lower planes.
A quasi‐assignment algorithm for bus scheduling
Authors: Paixão J. Pinto , Branco I. M.
Published: May 2007

A new and much faster algorithm is presented for the problem of assigning buses to a large number of short trips in an urban area. The trips are grouped into chains, beginning and ending at the same bus depot, and a vehicle is assigned to each one of them. Fleet size costs and dead heading time are to be minimized. This problem has been already formulated as a transportation problem and more recently, as an assignment model. However, some difficulties, such as the zero pivot phenomenon, rising in many practical cases drastically affected computing times required to obtain the optimal solution. This is overcome by an algorithm based on the hungarian method and making full use of the sparsity of the assignment matrix for the bus scheduling problem. Computational results comparing the different methods are given in the last section of the paper. Significant reductions in computing time are obtained for either real case applications or random generated test problems.
Computing k‐shortest path lengths in euclidean networks
Authors: Skiscim Christopher C. , Golden Bruce L.
Published: May 2007

In this paper, we examine the problem of finding k‐shortest paths between an origin and destination pair when distances are Euclidean. Two versions of a generalized Dijkstra algorithm are compared. Computational results show that the advantage of the adaptive version (measured by total number of permanent labels) grows with both k and the network size. For large networks, the adaptive algorithm exhibits a 100:1 advantage in the number of permanent labels set.
The complexity of minimum cut and maximum flow problems in an acyclic network
Authors: Ramachandran Vijaya
Published: May 2007

We establish that finding a minimum cut or a maximum flow in an acyclic network is no easier than the corresponding problem on a general network.
Bounding all‐terminal reliability in computer networks
Authors: Colbourn Charles J. , Harms Daryl D.
Published: May 2007

Many bounds for the all‐terminal reliability of computer networks have been proposed. Of those computable in polynomial time, the Ball‐Provan bounds and the Lomonosov Polesskii bounds provide the tightest estimates. A strategy is developed here using linear programming to obtain bounds which are tighter than both the Lomonosov‐Polesskii and the Ball‐Provan bounds. Computational results on these new bounds are also reported.
Convexity and the Steiner tree problem
Authors: Scott Provan J.
Published: May 2007

We investigate the role convexity plays in the efficient solution to the Steiner tree problem. In general terms, we show that a Steiner tree problem is always computationally easier to solve when the points to be connected lie on the boundary of a “convex” region. For the Steiner tree problem on graphs and the rectilinear Steiner tree problem, we give definitions of “convexity” for which this condition is sufficient to allow a polynomial algorithm for finding the optimal Steiner tree. For the classical Steiner tree problem, we show that for the standard definition of convexity, this condition is sufficient to allow a fully polynomial approximation scheme.
Planarity testing of doubly periodic infinite graphs
Authors: Iwano Kazuo , Steiglitz Kenneth
Published: May 2007

This paper describes an efficient way to test the VAP‐free (Vertex Accumulation Point free) planarity of one‐ and two‐dimensional dynamic graphs. Dynamic graphs are infinite graphs consisting of an infinite number of basic cells connected regularly according to labels in a finite graph called a static graph. Dynamic graphs arize in the design of highly regular VLSI circuits, such as systolic arrays and digital signal processing chips. We show that VAP‐free planarity testing of dynamic graphs can be done efficiently by making use of their regularity. First, we will establish necessary conditions for VAP‐free planarity of dynamic graphs. Then we show the existence of a small finite graph which is planar if and only if the original dynamic graph is VAP‐free planar. From this it follows that VAP‐free planarity testing of one‐ and two‐dimensional dynamic graphs is asymptomically no more difficult than planarity testing of finite graphs, and thus can be done in linear time.
Hemoglobin depletion from red blood cell cytosol reveals new proteins in 2‐D gel‐based proteomics study
Authors: Bhattacharya Dipankar , Mukhopadhyay Debashis , Chakrabarti Abhijit
Published: May 2007

Proteomics studies to identify proteins in the erythrocyte cytosol have been largely affected by the huge abundance of hemoglobin (Hb), which masks the detection of other proteins in the 2‐D gel‐based separation. We have depleted Hb effectively from erythrocyte cytosol using cation exchange chromatography and have detected more than 600 protein spots in the Hb depleted hemolysate using 2‐DE. We have so far identified 59 proteins in the Hb‐depleted cytosol of normal erythrocytes, including 10 proteins not identified before.
Testing AdS/CFT at string loops
Authors: Grignani G. , Orselli M. , Ramadanovic B. , Semenoff G.W. , Young D.
Published: May 2007

This article is based on the result obtained in hep‐th/0508126 and hep‐th/0605080 where we use the IIB light‐cone string field theory proposed by Dobashi and Yoneya to compute the one string‐loop correction to the energies of two impurity BMN states. We found that the result agrees with the gauge theory prediction at leading order – one‐loop in Yang‐Mills theory – and that is quite close also at second order in Yang‐Mills loops. We furthermore find that the half integer powers in the t'Hooft coupling are absent up to the 7/2 power.
Progress in D‐brane model building
Authors: Marchesano F.
Published: May 2007

The state of the art in D‐brane model building is briefly reviewed, focusing on recent achievements in the construction of D = 4 𝒩 = 1 type II string vacua with semi‐realistic gauge sectors. Such progress relies on a better understanding of the spectrum of BPS D‐branes, the effective field theory obtained from them and the explicit construction of vacua. We first consider D‐branes in standard Calabi‐Yau compactifications, and then the more involved case of compactifications with fluxes. We discuss how the non‐trivial interplay between D‐branes and fluxes modifies the previous model‐building rules, as well as provides new possibilities to connect string theory to particle physics.
Application of extended Hazop and event‐tree analysis for investigating operational failures and safety optimization of distillation column unit
Authors: Ramzan Naveed , Compart Fred , Witt Werner
Published: May 2007

Process safety has a high priority in the chemical industry. And the distillation is the most widely used unit operation in the chemical‐processing industries. The use of dynamic simulation for safety‐related studies for a distillation column has great significance for the study of operational failures. In this article, a systematic framework based on Extended Hazop and Event‐tree analysis is applied to a distillation column unit of a chemical plant. Over pressuring of column is studied and different safety system alternatives are generated and evaluated using Event‐tree analysis. This article describes the details of an effective method used for a distillation column but it can also be used for other hazardous unit operations. © 2007 American Institute of Chemical Engineers Process Saf Prog 2007
Time‐resolved nanosecond sub‐micron resolution thermal analysis of high‐power AlGaN/GaN HFETs
Authors: Kuball M. , Riedel G. J. , Pomeroy J. W. , Sarua A. , Uren M. J. , Martin T. , Hilton K. P. , Wallis D. J.
Published: May 2007

A novel time‐resolved micro‐Raman thermography technique has been developed to measure the active region temperature in AlGaN/GaN electronic devices, achieving a temporal and spatial resolution of 200 ns and 0.5–0.7 μm, respectively. AlGaN/GaN heterostructure field effect transistors (HFETs) grown on SiC and sapphire substrates are compared. Rapid temperature changes within 200 ns of current changes are followed by a slower change in device temperature. For a device on a SiC substrate an approximate temperature plateau is reached within 1–2 μs after switching the device on or off, illustrating its fast thermal response. This is in contrast to the slower time constant of devices on sapphire substrates where μs‐separated electrical pulses do not allow the devices to cool to room temperature between the electrical pulses. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐sensitivity UV phototransistor with GaN/AlGaN/GaN gate epi‐structure
Authors: Okada Masaya , Matsuura Kazuaki , Ao Jin‐Ping , Ohno Yasuo , Kawai Hiroji
Published: May 2007

A highly sensitive UV phototransistor was developed using AlGaN/GaN heterojunction field effect transistor (HFET) technology. The phototransistor consisted of a thin undoped GaN layer added on top of a conventional AlGaN/GaN HFET structure. In such a structure, holes generated in the surface i‐GaN layer are accumulated at the GaN/AlGaN interface, and they modulate the electrons in the FET channel. Due to this charge modulation effect, high photocurrent can be obtained. In the structure under study, hole life time was so long that a hole‐evacuating refresh operation was required for fast response and linear sensitivity. When irradiated with UV light of 360 nm, a device with 6 × 10–4 mm2 active area produced two hundred times higher photocurrent than a commercial Si UV diode with a much larger area. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nitride intersubband devices: prospects and recent developments
Authors: Julien F. H. , Tchernycheva M. , Nevou L. , Doyennette L. , Colombelli R. , Warde E. , Guillot F. , Monroy E.
Published: May 2007

This paper reports on GaN/AlN light‐emitting devices relying on intersubband transitions. All samples have been grown by molecular beam epitaxy. We first present a systematic investigation of single or coupled GaN/AlN quantum wells grown by MBE. We then present the recent observation of strong ISB resonant enhancement of the second‐harmonic generation of 1μm radiation. We finally report on the first observation of ISB luminescence in GaN QWs, which opens new prospects for the realization of nitride unipolar lasers based on current injection or optical pumping. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization of the luminescence emission in nanocrystalline SiGe/SiO2 multilayers
Authors: Rodríguez A. , Ortiz M. I. , Sangrador J. , Rodríguez T. , Avella M. , Prieto A. C. , Jiménez J. , Kling A. , Ballesteros C.
Published: May 2007

Luminescent multilayers of SiGe nanocrystals embedded in an oxide matrix have been fabricated by Low Pressure Chemical Vapour Deposition of SiGe and SiO2 in a single run followed by a Rapid Thermal Annealing treatment to crystallize the SiGe nanoparticles. Structural parameters like the diameter of the nanoparticles and the oxide interlayer thickness, as well as the annealing conditions have been investigated in order to get the maximum intensity of the luminescence emission. Structures with small nanoparticles (3–4.5 nm) separated by thick oxide barriers (≈35 nm) annealed at 900 °C for 60 s yield the maximum intensity as a result of a compromise between the appropriate crystallization of the small nanoparticles and a reduced degradation of their composition by Ge diffusion. An additional treatment at 450 °C in forming gas for dangling‐bond passivation increases the intensity of the luminescence by 25%. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the MTD‐PLS method to heterocyclic dye–cellulose interactions
Authors: Kurunczi Ludovic , Funar‐Timofei Simona , Bora Alina , Seclaman Edward
Published: May 2007

The minimal topologic difference method in a projection in latent structures variant procedure was applied to a series of heterocyclic monoazo dyes of the type: RC6H4N = NY (R = benzothiazole, benzimidazole, N‐containing aromatic pentacycles; Y = γ acid, H acid, chromotropic acid, R acid). A statistically excellent model was obtained: RX2 = 0.625, RY2 = 0.940, Q2 = 0.822. The analysis of this model reveals the nature of dye–fiber interactions, which determine the dye affinity. Hydrophobic character in the R group and H‐bond donor groups in a specific Y substitution position augment the dye affinity for cellulose. An increase of the polar nature of atoms in R depletes the affinity. Also some lateral substituents belonging to the Y coupling components suffer steric hindrance, and their presence is detrimental for the affinity. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
A quantum‐chemical study of n‐butane and of butane cation radical
Authors: Garifzianova Guzel G. , Tsyshevskii Roman V. , Shamov Alexander G. , Khrapkovskii Grigorii M.
Published: May 2007

A comparative computational study of the n‐butane and the butane cation radical is made by using the B3LYP density functional method with standard basis set 6‐31G(d). The conventional transition state theory was used to calculate the enthalpies of butane and its cation radical and the dissociation energies of the CC bond. Basis tendencies in parameter changes of the geometric and electronic structures of molecules and transition states, the enthalpies of formation, and the dissociation energies are analyzed. Computational results are compared with experimental data where possible. On the whole, the B3LYP method exhibits good agreement with experiment. Distinct values of barriers of the similar reactions of molecules and cation radicals are essential. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Investigation of the nanoscale self‐assembly of donor‐σ‐acceptor molecules
Authors: Sumpter Bobby G. , Meunier Vincent , Vázquez‐Mayagoitia Álvaro , Castellano Ronald K.
Published: May 2007

Electronic structure calculations are used to explore the nature of the interactions that lead to the self‐assembly of a new class of functionalized donor‐σ‐acceptor molecules, 1‐aza‐adamantanetriones (AATs), and the consequences of molecular structure on the resulting supramolecular systems. The results show how the self‐assembly process originates from the saturated core of the molecules that underlies their shape, conformational preferences, and dipole‐directed one‐dimensional assembly. The solvation properties of the monomers are explored and 1H NMR chemical shift values are determined and compared to experimental trends. A theoretical understanding of this class of supramolecular structures coupled with their molecular‐level tunability introduces the possibility to design novel functional materials for specific electronic and optoelectronic applications. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Douglas P. Taylor
Authors: Taylor Douglas P.
Published: May 2007

This article profiles my life and career highlights. I am an engineer who specializes in the mitigation of shock and vibration for structures of all types—from buildings and bridges to aircraft, naval vessels, and spacecraft. It is the story of how I entered the profession during the Cold War period and went on from there to invent many damping concepts. In some cases, names and project highlights have been omitted for security reasons. This is the nature of some of my work. Copyright © 2007 John Wiley & Sons, Ltd.
Ronald L. Mayes
Authors: Mayes Ronald L.
Published: May 2007

This paper presents a summary of the career of the author associated with his selection as the 2006 Structural Engineer of the Year. It spans his days as a student at the University of Auckland, New Zealand, as a research engineer at the University of California, Berkeley, and his consulting experience with Computech Engineering Services and SGH Inc. It includes his 6‐year tenure as the Technical and Executive Director of the Applied Technology Council and his 17 years with Dynamic Isolation Systems. Copyright © 2007 John Wiley & Sons, Ltd.
Responses of Daphnia magna to pulsed exposures of arsenic
Authors: Hoang Tham C. , Gallagher Jeffrey S. , Klaine Stephen J.
Published: May 2007

Research on the toxicity of arsenic has focused on sublethal effects that do not provide sufficient information for risk estimation. While most studies have focused on organism response to constant arsenic exposures, organisms in nature are exposed to fluctuating As concentrations. Consequently, results obtained from standardized bioassays with constant exposures may not adequately characterize risk to indigenous biota. This research was designed to characterize the response of Daphnia magna to fluctuating arsenic exposures during 21‐day experiments. At concentrations ≥3000 μg/L As, 21‐day pulsed exposure mortality increased as a function of exposure concentration and duration. In addition, 21‐day pulsed exposure mortality increased with increasing recovery time. Pulsed As exposure did not affect the growth of D. magna over 21 days. Twenty‐one day accumulative reproduction of D. magna was only affected by pulsed exposures of high As concentration and long durations. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 308–317, 2007.
Removal of estrogenic activity of 4‐tert‐octylphenol by ligninolytic enzymes from white rot fungi
Authors: Tamagawa Yuuki , Hirai Hirofumi , Kawai Shingo , Nishida Tomoaki
Published: May 2007

4‐tert‐Octylphenol (4‐t‐OP) was treated with the white rot fungus Phanerochaete sordida YK‐624 under ligninolytic condition with low‐nitrogen and high‐carbon culture medium. 4‐t‐OP completely disappeared after 5 days of treatment and the activities of ligninolytic enzymes, laccase and manganese peroxidase (MnP), were detected during this period, thus suggesting that the disappearance of 4‐t‐OP is related to these extracellular enzymes. Therefore, 4‐t‐OP was treated with laccase and MnP prepared from white rot fungi cultures. HPLC analysis demonstrated that 4‐t‐OP completely disappeared in the reaction mixture after 1 h of treatment with either laccase or MnP. Using the yeast two‐hybrid assay system, it was also confirmed that laccase and MnP substantially removed the estrogenic activity of 4‐t‐OP after 1 and 2 h of treatment, respectively. These results strongly demonstrate that ligninolytic enzymes are effective in removing the estrogenic activity of 4‐t‐OP. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 281–286, 2007.
Benchmark dose approach for renal dysfunction in workers exposed to lead
Authors: Lin Tian , Tai‐yi Jin
Published: May 2007

Benchmark dose (BMD) and the lower confidence limit on the benchmark dose (BMDL) of blood lead were estimated to explore the biologic exposure limits for renal dysfunction caused by lead. One hundred thirty‐five workers from one storage battery plant were selected as lead exposure group while 143 mechanics as the control. The relationship between the blood lead concentration and the urinary excretion of total protein (TP), β2‐microglobulin (β2‐MG), and N‐acetyl‐β‐D‐glucosaminidase (NAG) was studied. The quantal linear logistic regression model (BMDS Version 1.3.1) was used to calculate BMD and BMDL of blood lead. The results showed that the levels of NAG, β2‐MG, and TP in lead‐exposed workers were higher than those of control group and elevated along with rising length of employment. The levels of three indices for renal dysfunction increased with the elevated blood lead. The BMD and BMDL of blood lead for renal dysfunction were from 299.4 to 588.7 μg/L and from 253.4 to 402.3 μg/L, respectively. The BMDL of blood lead was ranged from high to low as TP, β2‐MG, and NAG. It is suggested that the urinary NAG activity could be a sensitive and early biomarker of renal tubular dysfunction induced by lead. When assessing renal function in workers occupationally exposed to lead, a blood lead level of 250 μg/L could serve as a warning signal. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 229–233, 2007.
Subacute toxicity evaluation in rats exposed to concrete and hwangto building environments
Authors: Lee Seung‐Won , Yang Young‐Su , Ahn Tai‐Hwan , Bae Chun‐Sik , Moon Chang‐Jong , Kim Sung‐Ho , Song Seung‐Yeong , Hwang Hey‐Zoo , Kim Jong‐Choon
Published: May 2007

This study examined the potential adverse effects of the subacute exposure of rats to concrete and hwangto building environments. Polycarbonate was used as a comparison. Groups of 10 male rats were exposed to polycarbonate, concrete, or hwangto cages for a 4‐week period in summer or winter. During the study period, the clinical signs, mortality, skin temperature, body weight, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, organ weights, and histopathology were examined. The concentration of total volatile organic compounds (VOCs), temperature, and relative humidity in the each cages were also measured. There were no exposure‐related effects in any group of the study examined in the summer. The temperature, relative humidity, and the concentration of VOCs in the cages were similar in all groups. However, in the winter study, significant differences in several parameters were detected among the groups. In the concrete group, there was an increase in the clinical signs, a reduction in the body weight gain, food intake, and liver weight, an increase in the lung weight, and an increase in the histopathological alterations in the lung and thymus. Infrared thermal analysis showed that the skin temperature of the rats in the concrete group was lower than that in the polycarbonate group. However, in the hwangto group, there was a decrease in the clinical signs and an increase in the body weight, food intake, and the weights of the heart, lung, spleen, and epididymides. Overall, the 4‐week exposure of the rats to the concrete building environment had adverse effects on the clinical signs, skin temperature, body weight, and some organs in the winter but not in the summer. On the other hand, the exposure of hwangto building environment did not have any exposure‐related adverse effects on the general health parameters and skin temperature in rats. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 264–274, 2007.
Copper and zinc tolerance of two tropical microalgae after copper acclimation
Authors: Johnson Hilary L. , Stauber Jenny L. , Adams Merrin S. , Jolley Dianne F.
Published: May 2007

Current toxicity tests with microalgae are often criticized as being overly sensitive to metals because algae are cultured in metal‐deficient media. If such bioassays overestimate copper toxicity in surface waters, the relevance of water quality guidelines derived from these tests is questionable. In this study, the effect of acclimation to copper at environmentally relevant concentrations, on the sensitivity of the marine diatom Nitzschia closterium and the freshwater green alga Chlorella sp. to copper and zinc was examined. N. closterium was acclimated in culture medium containing 5 or 25 μg Cu L−1 for 200 days, while Chlorella sp. was acclimated in medium containing 2 μg Cu L−1 for 100 days. Changes in algal growth rates and copper and zinc tolerance were monitored using standard growth inhibition toxicity tests in minimal medium over 72 h. Neither of the two acclimated N. closterium cultures had increased zinc or copper tolerance compared with that of the nonacclimated algae, nor were there any changes in control growth rates. Similarly, no changes in copper tolerance or control growth rates were observed for the acclimated Chlorella sp. culture. This was supported by measurements of intracellular and extracellular copper which confirmed that there were no differences in copper accumulation in either acclimated or nonacclimated algae. These results suggest that these algae grown in standard culture media are generally no more sensitive than algae grown in a metal‐enriched medium. This supports the continued use of current laboratory bioassays with microalgae, as part of a suite of tests for assessing metal bioavailability, for use in ecological risk assessments and for providing data for the derivation of water quality guidelines. © 2007 Wiley Periodicals, Inc. Environ Toxicol 22: 234–244, 2007.
8. Genital lumps and bumps: what is normal?
Authors: O'Mahony Colm
Published: May 2007

When patients present with genital ‘lesions’, it is important to distinguish between normal anatomical variants, which usually require only reassurance, and other similar‐appearing conditions such as genital warts. Dr O'Mahony provides an illustrated account of some common normal genital lumps and bumps. Copyright © 2007 Wiley Interface Ltd
Prenatal three‐dimensional ultrasound: perception of sonographers, sonologists and undergraduate students
Authors: Lee S. , Pretorius D. H. , Asfoor S. , Hull A. D. , Newton R. P. , Hollenbach K. , Nelson T. R.
Published: May 2007

Objective

To assess the perception of non‐pregnant sonographers, sonologists and undergraduate students on the use of three‐dimensional (3D) ultrasound technology in fetal medicine.

Methods

This was a study of two groups of non‐pregnant subjects. Group I included 520 (305 female, 215 male) medical professionals who completed a questionnaire after attending a lecture on 3D imaging. Factors such as gender, career and having children were analyzed with respect to the attendee's responses about use of 3D ultrasound for medical purposes and for reassurance. Group II included 137 (75 female, 60 male, two unknown) undergraduate students from bioengineering, psychology and physiology classes who completed a questionnaire after attending a brief presentation on two‐dimensional and 3D fetal imaging. Factors such as gender and area of educational interest were analyzed with respect to the students' responses about the use of 3D ultrasound for medical purposes and for parental–fetal attachment.

Results

In Group I, 63% said that they would like to have a 3D ultrasound examination in the future, while 14% said that they would not. Common reasons given for wanting a 3D ultrasound exam in the future were for medical purposes (39%) or reassurance (18%). The main differences perceived between two‐dimensional (2D) and 3D ultrasound were medical advantages (65%) and parental reassurance (28%). 62.4% of Group I thought 3D technology should be in wide use in obstetric ultrasound and 73.6% thought that 3D ultrasound would reassure parents carrying normal fetuses. Gender, age and career did not have a significant influence on perception of 3D ultrasound. In Group II, the majority (91%) said they could see a remarkable difference between 2D and 3D ultrasound. 83% responded that they would like to have a 3D ultrasound examination of their own baby in the future for the following reasons: 34% for the detailed picture, 31% for increased abnormality detection, 13% for reassurance or curiosity; 8% thought it would be unnecessary or a negative experience. Concerning parental–fetal attachment, 72% thought 3D ultrasound would have a positive effect. The majority of Group II (93%) thought 3D ultrasound would be valuable and 56% thought 3D ultrasound would assist in diagnosing fetal abnormalities. There was no significant relationship between gender, age or area of interest and the perception of 3D ultrasound.

Conclusions

Responses by sonographers and physicians suggest that 3D ultrasound will have a role in the future for medical indications and in reassuring patients carrying normal fetuses. Our results also suggest that undergraduate students believe that 3D ultrasound will be a valuable technique in obstetrics and that it will have a positive effect on parental–fetal attachment. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Genetics Support to Primary Care Practitioners—A Demonstration Project
Authors: Drury N. , Bethea J. , Guilbert P. , Qureshi N.
Published: May 2007

Primary care practitioners need to be supported by specialist genetics services to enable them to cope effectively with the expanding relevance of genetics to their patients. Genetic counselors could be effective in such a role. This exploratory project set out to improve the Primary–Tertiary interface through piloting such a service to general practice for 1 year. Tailored genetic educational outreach was delivered by a genetic counselor to ten randomly selected general practices in central England for 12 months. A range of services were provided to the practices these included facilitated genetic update sessions, a responsive advice service and referral guidelines. The service was evaluated through pre and post intervention questionnaires and via seven semi‐structured interviews. This article presents a description of the development and delivery of this service and also reports on the experiences of a sample of the participants. Participants reported positive attitudes to the service and said that they had gained knowledge and confidence, as well as recognized limitations and gaps in their current knowledge. The consistent link with a specialist genetics service provided by a genetic counselor had a positive impact during the project and participants have continued to utilize the genetic counselor for advice and support with genetic patient issues since the project was completed. This is the first example of this model of service provision. Further research, utilizing a larger sample and other measures of behavioral change needs to be carried out to assess whether this model should be adopted on a wider basis.
Recommendations from Multi‐disciplinary Focus Groups on Cascade Testing and Genetic Counseling for Fragile X‐associated Disorders
Authors: McConkie‐Rosell Allyn , Abrams Liane , Finucane Brenda , Cronister Amy , Gane Louise W. , Coffey Sarah M. , Sherman Stephanie , Nelson Lawrence M. , Berry‐Kravis Elizabeth , Hessl David , Chiu Sufen , Street Natalie , Vatave Ajay , Hagerman Randi J.
Published: May 2007

The purpose of this paper is to report the outcome of a collaborative project between the Fragile X Research and Treatment Center at the Medical Investigation of Neurodevelopmental Disorders (M.I.N.D.) Institute at the University of California at Davis, the National Fragile X Foundation (NFXF), and the Centers for Disease Control and Prevention (CDC). The objective of this collaboration was to develop and disseminate protocols for genetic counseling and cascade testing for the multiple disorders associated with the fragile X mental retardation 1 (FMR1) mutation. Over the last several years, there has been increasing insight into the phenotypic range associated with both the premutation and the full mutation of the FMR1 gene. To help develop recommendations related to screening for fragile X‐associated disorders, four, two day advisory focus group meetings were conducted, each with a different theme. The four themes were: (1) fragile X‐associated tremor/ataxia syndrome (FXTAS); (2) premature ovarian failure (POF) and reproductive endocrinology; (3) psychiatric, behavioral and psychological issues; and (4) population screening and related ethical issues.
IN THIS ISSUE
Authors: MORGAN CRAIG
Published: May 2007

This issue contains two reviews, one on how well the Beck Hopelessness Scale can predict suicide and self-harm, and one on the validity of the distinction between bereavement-related and non-bereavement-related depression. Other sets of papers examine various aspects of suicide and depression.
Warhorse and post-nomadic empire in Asia, c. 1000–1800
Authors: Gommans Jos
Published: May 2007

Until the nineteenth century the warhorse played a central role in the political organization of the great empires that bordered on the pastoral heartlands of Central Eurasia. Actually, the survival of the often (semi-)nomadic rulers of these frontier-empires hinged on the continued production, trade and use of Central Eurasian warhorses. This forestalled the full sedentarization of these rulers and conditioned the emergence of a post-nomadic political culture and organization in which Central Eurasian institutions like ordo, nökör and yurt continued to provide a forceful paradigm to mobilize, organize and enumerate cavalry armies. But as the specific ecological circumstances created different conditions for the breeding and trade of warhorses, they also gave rise to different interpretations of the nomadic paradigm. This is demonstrated in the case of the Mughal rulers in India and the Manchu-Qing rulers in China, who both shared a common Central Eurasian heritage and ruled the richest sedentary economies of their time.
Outer rise stress changes related to the subduction of the Juan Fernandez Ridge, central Chile
Authors: Clouard V. , Campos J. , Lemoine A. , Perez A. , Kausel E.
Published: May 2007

Although outer rise seismicity is less common than interplate seismicity in subduction zones, a significant level of seismicity has occurred between the Nazca trench and Juan Fernandez Ridge, in central Chile, during the past 20 years. We first study the 9 April 2001 (Mw = 7.0) event and determine its focal mechanism, depth, and source time function by body‐waveform inversion from teleseismic broadband data. The results indicate tensional faulting in the upper part of the mechanical lithosphere. Its strike (41°) is similar to those observed in events down dip of the slab at about 100 km depth, which could indicate that these earthquakes occur in preexisting structures formed at the trench. Compressive outer rise events have also occurred during the 1980s in front of the rupture zone of the 1985 Mw 7.8 Valparaíso Earthquake. To understand their relation with the state of stress of the lithosphere, we construct yield stress envelopes of the oceanic lithosphere, including static and dynamic stresses. Dynamic stresses are due either to slab pull, ridge push, resistive, and drag forces. We explain the sequence of compressive and tensional events by the accumulation of stress prior to 1985 when the subduction is assumed to be locked and after by the unlockage of the subduction by the Valparaíso interplate event. The yield stress envelope analysis enables us to quantify the accumulation of compressive forces before 1985 and the tensional force after.
Multiple lines of evidence for crustal magma storage beneath the Mesozoic crystalline Iide Mountains, northeast Japan
Authors: Umeda Koji , Asamori Koichi , Ninomiya Atusi , Kanazawa Sunao , Oikawa Teruki
Published: May 2007

It has been recognized that the Iide Mountains, consisting of Mesozoic sedimentary rocks and Late Cretaceous to Paleogene granitic rocks, northeast Japan, are unique. Although they occur in a nonvolcanic region, hot springs in the Iide Mountains have anomalously high heat discharge values similar to those from hot springs in volcanic regions. In order to provide geochemical constraints on the heat source for the hydrothermal activity, the chemical and isotopic compositions of 10 gas and water samples were determined. The 3He/4He ratios determined range from 0.22 to 7.9 Ra, and the highest ratio is similar to MORB‐type helium, indicating a significant contribution of primordial mantle helium. Considering the relationship between the magnitude of the 3He/4He ratios and the distance of the sample locations from the Kitamata‐dake, the peak in the Iide Mountains where the largest ratio occurs, it is apparent that there is a sharp decrease in 3He/4He ratios laterally away from the peak. Furthermore, the peak is also the location where geophysical anomalies such as an anomalous conductive body and zones with low Vp and low Vs have been detected in the middle‐lower crust. These high helium ratios are considered to indicate the likelihood of mantle‐derived materials supplying MORB‐type helium beneath the Kitamata‐dake and the possibility that mantle‐derived helium has been diluted by atmospheric and/or crustal components with lower helium ratios away from the peak. In order to examine whether or not ancient magma of Middle Miocene age is a possible source of the high 3He/4He ratios of the hot spring gases, we calculated the evolution in 3He/4He ratios of the ancient magma with time. As a result, it is concluded that the anomaly beneath the Iide Mountains is due to newly ascending magmas in the present‐day subduction system rather than hydrothermal fluids related to late remnant magmatism of Middle Miocene age.
Postseismic quasi‐static fault slip due to pore pressure change on a bimaterial interface
Authors: Yamashita Teruo
Published: May 2007

We theoretically study the mechanism of afterslip, generally observed after the occurrence of large shallow earthquakes, taking account of poroelastic effects including fluid flow. A two‐dimensional in‐plane shear fault is assumed on a bimaterial interface that separates mechanically different poroelastic media. We first derive analytical expressions for the stress tensor components and fluid pressure as integrals of fault slip; the rigidity and diffusivity of the two media separated by the fault are assumed to be equal in value to derive the solution analytically. We then numerically solve these integral equations assuming stress boundary condition on the fault and obtain the spatiotemporal evolution of fault slip. The Coulomb failure criterion is assumed for the quasi‐static growth of fault. We find that the positive feedback between the fluid pressure raised at the extending fault tip and evolving fault slip promotes the quasi‐static fault tip extension; the amount of afterslip is found to be larger for smaller value of the Biot‐Willis coefficient. It is also found that the poroelastic bimaterial effect favors unilateral extension of fault. Our calculations show that the patch of postseismic fault slip does not overlap that of coseismic slip significantly. We also observe a rapid decrease in postseismic moment release rate with time. These are in harmony with geodetic observation related to afterslips. We will have to resort to purely numerical analysis if we remove the assumptions about the rigidity and diffusivity; however, our present study can provide a reference point for such analysis.
Reconnection onset in the magnetotail: Particle simulations with open boundary conditions
Authors: Divin A. V. , Sitnov M. I. , Swisdak M. , Drake J. F.
Published: May 2007

The mechanism of the onset of magnetic reconnection in collisionless plasmas in the tails of planetary magnetospheres and similar processes in the solar corona is one of the most fundamental and yet not fully solved problems of space plasma physics. Modeling the onset with particle codes requires either extremely large simulation boxes or open boundary conditions. In this Letter we report on simulations of reconnection in the magnetotail that incorporate open boundaries. In a simulation setup with the initial geometry similar to that of the GEM Reconnection Challenge bursts of spontaneous reconnection are detected in outflow regions that mimic magnetotails. They strongly resemble the ion tearing instability predicted by Schindler [1974] as a mechanism of magnetospheric substorms. Quenching the onset by replacing open boundary conditions for particles with their reintroduction reveals the key role of passing particles in the tearing destabilization.