bluuebunny/crossref_metadata_2025 huggingface dataset:
Book Reviews
Authors: Miles Jeremy
Published: May 2006

Designing experiments and analysing data: A model comparison approach

By Maxwell Scott E. & Delaney Harold D. (2nd edn)

Mahwah, NJ: Lawrence Erlbaum 2004. Cased, ISBN: 0‐8058‐3718‐3, £39.95/$89.95
The Impact of Strategic Fit among Strategy, Structure, and Processes on Multinational Corporation Performance: A Multimethod Assessment
Authors: Xu Shichun , Cavusgil S. Tamer , White J. Chris
Published: May 2006

The international marketing literature has produced divergent findings regarding the effect of a standardized marketing strategy on firm performance among large multinational corporations (MNCs). Prior research has typically considered external or environmental factors to reconcile different findings. This study employs multiple perspectives of strategic fit (moderation, mediation, profile deviation, and covariation) to examine the effect of the internal fit among strategy, structure, and processes of MNCs and explores their effects on firm performance. Empirical results based on 206 MNCs support the mediation, profile deviation, and covariation perspectives, but they fail to confirm the moderation perspective.
Internationalization Processes: The Case of Automotive Suppliers in China
Authors: Kaufmann Lutz , Jentzsch Andreas
Published: May 2006

The article introduces a conceptual framework of internationalization processes and provides case study–based empirical insights. The aim is to analyze combinations of internationalization strategies and modes that automotive suppliers expanding into China have chosen and their evolution paths over time. In addition, the authors identify parameters that may explain why foreign entrants change their internationalization strategies and modes over time.
The Litigated Dissolution of International Distribution Relationships: A Process Framework and Propositions
Authors: Zhang Chun , Griffith David A. , Cavusgil S. Tamer
Published: May 2006

The litigated dissolution of international distribution relationships severely hampers exchange partners’ international efforts. Although relationship dissolution through litigation is a central issue in international business, limited research has been conducted to understand this process, thus leaving academics and practitioners with an incomplete theoretical or practitioner understanding of issues involved in this process. This study uses a systematic analysis of legal cases over the 1985–2005 period to better understand this issue from a longitudinal perspective. Using legal case data, the authors develop a process framework, which includes formalized propositions, to denote two separate litigation dissolution processes: proactive and reactive. The legal case analysis indicates that the two types of relationship dissolution processes have unique triggers and outcomes, which suggests differences in theoretical models and managerial actions. The authors present academic and practitioner implications.
Real algebraic morphisms on 2-dimensional conic bundles
Authors: Mangolte Frédéric
Published: May 2006

Given two nonsingular real algebraic varieties V and W, we consider the problem of deciding whether a smooth map f : V → W can be approximated by regular maps in the space of 𝒞∞ mappings from V to W in the 𝒞∞ topology. Our main result is a complete solution to this problem in case W is the usual 2-dimensional sphere and V is a real algebraic surface of negative Kodaira dimension.
Geodesics in non-positively curved plane tessellations
Authors: Baues Oliver , Peyerimhoff Norbert
Published: May 2006

We introduce a natural combinatorial curvature function on the corners of plane tessellations and relate it to the global metric geometry of their corresponding edge and dual graphs. If the combinatorial curvature in the corners is non-positive then we prove that any geodesic path in such a graph may be extended to infinity. Moreover, if the combinatorial curvature is negative we show that every pair of geodesic segments with the same end points does not enclose any vertices. We apply these results to establish an estimate for the growth of distance balls, Gromov hyperbolicity, and four-colourability of certain classes of plane tessellations.
Representation type of Schur superalgebras
Authors: Hemmer David J , Kujawa Jonathan , Nakano Daniel K
Published: May 2006

Let S(m|n, d) be the Schur superalgebra whose supermodules correspond to the polynomial representations of the supergroup GL(m|n) of degree d. In this paper we determine the representation type of these algebras (that is, we classify the ones which are semisimple, have finite, tame and wild representation type). Moreover, we prove that these algebras are in general not quasi-hereditary and have infinite global dimension.
Embedding groups in locally (soluble-by-finite) simple groups
Authors: Dixon Martyn R , Evans Martin J , Smith Howard
Published: May 2006

The authors investigate the structure of locally (soluble-by-finite) simple groups
Ĝ
and show that such groups are locally residually finite. Sufficient conditions are given for a group G to be embeddable in such a group
Ĝ
and an example of a locally (abelian-by-finite) simple group is constructed.
Fine-Scale Map of Encyclopedia of DNA Elements Regions in the Korean Population
Authors: Yoo Yeon-Kyeong , Ke Xiayi , Hong Sungwoo , Jang Hye-Yoon , Park Kyunghee , Kim Sook , Ahn TaeJin , Lee Yeun-Du , Song Okryeol , Rho Na-Young , Lee Moon Sue , Lee Yeon-Su , Kim Jaeheup , Kim Young J , Yang Jun-Mo , Song Kyuyoung , Kimm Kyuchan , Weir Bruce , Cardon Lon R , Lee Jong-Eun , Hwang Jung-Joo
Published: May 2006

The International HapMap Project aims to generate detailed human genome variation maps by densely genotyping single-nucleotide polymorphisms (SNPs) in CEPH, Chinese, Japanese, and Yoruba samples. This will undoubtedly become an important facility for genetic studies of diseases and complex traits in the four populations. To address how the genetic information contained in such variation maps is transferable to other populations, the Korean government, industries, and academics have launched the Korean HapMap project to genotype high-density Encyclopedia of DNA Elements (ENCODE) regions in 90 Korean individuals. Here we show that the LD pattern, block structure, haplotype diversity, and recombination rate are highly concordant between Korean and the two HapMap Asian samples, particularly Japanese. The availability of information from both Chinese and Japanese samples helps to predict more accurately the possible performance of HapMap markers in Korean disease-gene studies. Tagging SNPs selected from the two HapMap Asian maps, especially the Japanese map, were shown to be very effective for Korean samples. These results demonstrate that the HapMap variation maps are robust in related populations and will serve as an important resource for the studies of the Korean population in particular.
Natural Variation inMAMWithin and Between Populations ofArabidopsis lyrataDetermines Glucosinolate Phenotype
Authors: Heidel Andrew J , Clauss Maria J , Kroymann Juergen , Savolainen Outi , Mitchell-Olds Thomas
Published: May 2006

The genetic variation that underlies the glucosinolate phenotype of Arabidopsis lyrata ssp. petraea was investigated between and within populations. A candidate glucosinolate biosynthetic locus (MAM, containing methylthioalkylmalate synthase genes) was mapped in A. lyrata to a location on linkage group 6 corresponding to the homologous location for MAM in A. thaliana. In A. thaliana MAM is responsible for side chain elongation in aliphatic glucosinolates, and the MAM phenotype can be characterized by the ratios of long- to short-chain glucosinolates. A quantitative trait loci (QTL) analysis of glucosinolate ratios in an A. lyrata interpopulation cross found one QTL at MAM. Additional QTL were identified for total indolic glucosinolates and for the ratio of aliphatic to indolic glucosinolates. MAM was then used as the candidate gene for a within-population cosegregation analysis in a natural A. lyrata population from Germany. Extensive variation in microsatellite markers at MAM was found and this variation cosegregated with the same glucosinolate ratios as in the QTL study. The combined results indicate that both between- and within-population genetic variation in the MAM region determines phenotypic variation in glucosinolate side chains in A. lyrata.
PAPPA2, an Enzyme That Cleaves an Insulin-Like Growth-Factor-Binding Protein, Is a Candidate Gene for a Quantitative Trait Locus Affecting Body Size in Mice
Authors: Christians Julian K , Hoeflich Andreas , Keightley Peter D
Published: May 2006

Identifying genes responsible for quantitative variation remains a major challenge. We previously identified a quantitative trait locus (QTL) affecting body size that segregated between two inbred strains of mice. By fine mapping, we have refined the location of this QTL to a genomic region containing only four protein-coding genes. One of these genes, PAPPA2, is a strong candidate because it codes for an enzyme that cleaves insulin-like growth-factor-binding protein 5 (IGFBP-5), an important stimulator of bone formation. Among littermates that segregate only for the four-gene region, we show that the QTL has a significant effect on the circulating levels of IGFBP-5 and IGFBP-3 (the latter subject to limited degradation by PAPPA2), but not on levels of IGFBP-2 and IGFBP-4, which are not cleaved by PAPPA2. There are 14 nonsynonymous SNPs among QTL alleles, which may affect the activity of the translated protein. The refinement of the target region to four genes and the finding that the QTL affects IGFBP-5 levels suggest that PAPPA2 may be involved with normal postnatal growth. Our mapping results also illustrate the potentially fractal nature of QTL: as we mapped our QTL with increasing resolution, what appeared to be a single QTL resolved into three closely linked QTL (previous work), and then one of these was further dissected into two in this study.
Discovery and Mapping of Wheat Ph1 Suppressors
Authors: Dvorak J , Deal K R , Luo M-C
Published: May 2006

Pairing between wheat (Triticum turgidum and T. aestivum) homeologous chromosomes is prevented by the expression of the Ph1 locus on the long arm of chromosome 5B. The genome of Aegilops speltoides suppresses Ph1 expression in wheat × Ae. speltoides hybrids. Suppressors with major effects were mapped as Mendelian loci on the long arms of Ae. speltoides chromosomes 3S and 7S. The chromosome 3S locus was designated Su1-Ph1 and the chromosome 7S locus was designated Su2-Ph1. A QTL with a minor effect was mapped on the short arm of chromosome 5S and was designated QPh.ucd-5S. The expression of Su1-Ph1 and Su2-Ph1 increased homeologous chromosome pairing in T. aestivum × Ae. speltoides hybrids by 8.4 and 5.8 chiasmata/cell, respectively. Su1-Ph1 was completely epistatic to Su2-Ph1, and the two genes acting together increased homeologous chromosome pairing in T. aestivum × Ae. speltoides hybrids to the same level as Su1-Ph1 acting alone. QPh.ucd-5S expression increased homeologous chromosome pairing by 1.6 chiasmata/cell in T. aestivum × Ae. speltoides hybrids and was additive to the expression of Su2-Ph1. It is hypothesized that the products of Su1-Ph1 and Su2-Ph1 affect pairing between homeologous chromosomes by regulating the expression of Ph1 but the product of QPh.ucd-5S may primarily regulate recombination between homologous chromosomes.
Natural History of Transposition in the Green Alga Chlamydomonas reinhardtii: Use of the AMT4 Locus as an Experimental System
Authors: Kim Kwang-Seo , Kustu Sydney , Inwood William
Published: May 2006

The AMT4 locus of the green alga Chlamydomonas reinhardtii, which we mapped to the long arm of chromosome 8, provides a good experimental system for the study of transposition. Most mutations that confer resistance to the toxic ammonium analog methylammonium are in AMT4 and a high proportion of spontaneous mutations are caused by transposon-related events. Among the 15 such events that we have characterized at the molecular level, 9 were associated with insertions of the retrotransposon TOC1, 2 with a small Gulliver-related transposon, and 1 with the Tcr1 transposon. We found that Tcr1 is apparently a foldback transposon with terminal inverted repeats that are much longer and more complex than previously realized. A duplication of Tcr1 yielded a configuration thought to be important for chromosomal evolution. Other mutations in AMT4 were caused by two mobile elements that have not been described before. The sequence of one, which we propose to call the Bill element, indicates that it probably transposes by way of a DNA intermediate and requires functions that it does not encode. The sequence of the other and bioinformatic analysis indicates that it derives from a miniature retrotransposon or TRIM, which we propose to call MRC1 (miniature retrotransposon of Chlamydomonas).
Developmental Modulation of Nonhomologous End Joining in Caenorhabditis elegans
Authors: Clejan Iuval , Boerckel Julie , Ahmed Shawn
Published: May 2006

Homologous recombination and nonhomologous end joining (NHEJ) are important DNA double-strand break repair pathways in many organisms. C. elegans strains harboring mutations in the cku-70, cku-80, or lig-4 NHEJ genes displayed multiple developmental abnormalities in response to radiation-induced DNA damage in noncycling somatic cells. These phenotypes did not result from S-phase, DNA damage, or mitotic checkpoints, apoptosis, or stress response pathways that regulate dauer formation. However, an additional defect in him-10, a kinetochore component, synergized with NHEJ mutations for the radiation-induced developmental phenotypes, suggesting that they may be triggered by mis-segregation of chromosome fragments. Although NHEJ was an important DNA repair pathway for noncycling somatic cells in C. elegans, homologous recombination was used to repair radiation-induced DNA damage in cycling somatic cells and in germ cells at all times. Noncycling germ cells that depended on homologous recombination underwent cell cycle arrest in G2, whereas noncycling somatic cells that depended on NHEJ arrested in G1, suggesting that cell cycle phase may modulate DNA repair during development. We conclude that error-prone NHEJ plays little or no role in DNA repair in C. elegans germ cells, possibly ensuring homology-based double-strand break repair and transmission of a stable genome from one generation to the next.
Ductus Arteriosus Aneurysm With Community-Acquired Methicillin-Resistant Staphylococcus aureus Infection and Spontaneous Rupture: A Potentially Fatal Quandary
Authors: Stewart Audra , Dyamenahalli Umesh , Greenberg S. Bruce , Drummond-Webb Jonathan
Published: May 2006

We present the case of a 6-month-old previously healthy girl who presented with high fever, labored breathing, and an enlarged cardiac silhouette on her chest radiograph. Comprehensive evaluation discovered a ductus arteriosus aneurysm and pericardial effusion with methicillin-resistant Staphylococcus aureus bacteremia. Despite pericardiocentesis and appropriate intravenous antibiotics, there was rapid enlargement of the aneurysm and accumulation of echogenic material within the ductus arteriosus aneurysm. Infected aneurysm rupture was identified during emergency surgery. This infant also had vocal cord paresis, a likely complication of the surgery. The clinical course, diagnosis, and treatment of this patient are discussed. Infection of a ductus arteriosus or an infected ductal arteriosus aneurysm is a rare and potentially fatal clinical entity. In the era of increasing community-acquired methicillin-resistant S aureus infections, this is a diagnosis that requires a high index of suspicion.
Relevance of Sunscreen Application Method, Visible Light and Sunlight Intensity to Free‐radical Protection: A Study of ex vivo Human Skin
Authors: Haywood Rachel
Published: May 2006

With the continued rise in skin cancers worldwide there is a need for effective skin protection against sunlight damage. It was shown previously that sunscreens, which claimed UVA protection (SPF 20+), provided limited protection against UV‐induced ascorbate radicals in human skin. Here the results of an electron spin resonance (ESR) investigation to irradiate ex vivo human skin with solar‐simulated light are reported. The ascorbate radical signal in the majority of skin samples was directly proportional to the irradiance over relevant sunlight intensities (0.9–2.9 mW cm−2). Radical production (substratum‐corneum) by UV (wavelengths <400 nm) and visible components (>400 nm) was ∼67% and 33% respectively. Ascorbate radicals were in steady state concentration at low irradiance (∼1 mW cm−2 equivalent to UK sunlight), but at higher irradiance (∼3 mW cm−2) decreased with time, suggesting ascorbate depletion. Radical protection by a four star‐rated sunscreen (with UVA protection) was optimal when applied as a thin film (40–60% at 2 mg cm−2) but less so when rubbed into the skin (37% at 4 mg cm−2 and no significant protection at 2 mg cm−2), possibly due to cream filling crevices, which reduced film thickness. This study validates ESR determinations of the ascorbate radical for quantitative protection measurements. Visible light contribution to radical production, and loss of protection when sunscreen is rubbed into skin, has implications for sunscreen design and use for the prevention of free‐radical damage.
Towards a Functional Dissection of Thioredoxin Networks in Plant Cells†
Authors: Hisabori Toru , Motohashi Ken , Hosoya‐Matsuda Naomi , Ueoka‐Nakanishi Hanayo , Romano Patrick G. N.
Published: May 2006

Thioredoxins are a ubiquitous family of redox equivalent mediators, long considered to possess a limited number of target enzymes. Recent progress in proteomic research has allowed the identification of a wide variety of candidate proteins with which this small protein may interact in vivo. Moreover, the activity of thioredoxin itself has been recently found to be subject to regulation by posttranslational modifications, adding an additional level of complexity to the function of this intriguing enzyme family. The current review charts the technical progress made in the continuing discovery of the numerous and diverse roles played by these proteins in the regulation of redox networks in plant cells.
Molecular Mechanisms Characterizing Cone Photoresponses†
Authors: Tachibanaki Shuji , Shimauchi‐Matsukawa Yoshie , Arinobu Daisuke , Kawamura Satoru
Published: May 2006

In the vertebrate retina, rods mediate twilight vision and cones mediate daylight vision. Their photoresponse characteristics are different. The light‐sensitivity of a cone is 102–103 times lower than that of a rod. In addition, the photoresponse time course is much faster in cones. The mechanism characterizing cone photoresponses has not been known mainly because of the difficulty in isolating cones in large quantities to perform biochemistry. Recently, we developed a method to purify cones from carp retina using a density gradient, which made it possible to analyze the differences in the molecular mechanism of phototransduction between rods and cones. The results showed that signal amplification in cones is less effective, which explains the lower light‐sensitivity of cones. The results also showed that visual pigment phosphorylation, a quenching mechanism of light‐activated visual pigment, is much more rapid in cones than in rods. The rapid phosphorylation in cones is attributed to a very high total kinase activity in cones. Because of this high activity, cone pigment is readily phosphorylated even at very high bleaching levels, which probably explains why cone photoresponses recover quickly. Based on these findings, the molecular mechanisms of the differences in the photoresponse characteristics between rods and cones are outlined.
Seismic stability of reinforced-soil wall by pseudo-dynamic method
Authors: Nimbalkar S. S. , Choudhury D. , Mandal J. N.
Published: May 2006

Determination of the internal stability of reinforced soil walls under earthquake conditions is an important part of seismic design. The horizontal method of slices is used for determining internal stability or for tieback analysis of the reinforced soil wall. A pseudo-dynamic method is adopted in the present analysis, which considers the effect of phase difference in both the shear and primary waves travelling through the backfill due to seismic excitation. Reinforced soil walls with cohesionless backfill material have been considered in the analysis. Results are presented in graphical and tabular form to show the required tensile force and length of geosynthetic reinforcement to maintain the stability of the reinforced soil wall under seismic conditions. The effects of variation of parameters such as soil friction angle and horizontal and vertical seismic accelerations on the stability of the reinforced soil wall have been studied. With an increase of seismic accelerations in both the horizontal and vertical directions the stability of the reinforced soil wall decreases significantly, and thus greater strength and length of the geosynthetic reinforcement are required to maintain stability of the wall. The seismic vertical acceleration in an upward direction gives higher values of the required geosynthetic tensile strength, and the seismic vertical acceleration in the downward direction yields higher values of the length of geosynthetic reinforcement. Comparisons of the present results with available pseudo-static results are shown, and the limitations of the pseudo-static results are highlighted.
Laboratory simulation of installation damage of a geogrid
Authors: Huang C.-C.
Published: May 2006

A series of laboratory cyclic loading tests was performed to investigate the effects of load intensity and particle size of aggregates on installation damage of a flexible geogrid. Stress–strain characteristics of the damaged flexible geogrid are also compared with those obtained from some full-scale tests reported in the literature. The test results were as follows. The load intensity and particle size have major influences on the installation damage of the flexible geogrid investigated. A relatively small particle size as specified in a standard laboratory test (DD ENV ISO 10722-1) may generate unconservative results when larger particle sizes dominate in the infield soils. Load intensities ranging between 400 and 900 kPa induce similar amounts of strength loss of the geogrid compared with that obtained in the full-scale field tests. A change in loading frequencies between 0.1 and 3.0 Hz introduces no measurable difference in the damage of the geogrid. The use of loading cycles (N) greater than 200 introduces no further damage in the geogrid when compared with the damage using N = 200. The reduction in tensile stiffness at 5% strain is significantly lower than the reduction in ultimate strength for the damaged geogrid. Results of visual examination of the damaged geogrid show that damage evaluations based on visual inspection of a retrieved sample are feasible only when a calibration curve presenting a relationship between the number of damaged points and the strength loss for specific site and geogrid conditions has been established in advance.
Formation of a cultivated spodosol in east-central Finland
Authors: YLI-HALLA M. , MOKMA D. L. , WILDING L. P.
Published: May 2006

The processes involved in Spodosol (Podzol) formation are still being debated. The pedogenic processes in a Spodosol, 10,700 years-old, at Sotkamo that has been cultivated for about 50 years were studied by characterizing the morphology and analyzing the major chemical properties, texture and mineralogy. Before cultivation, organic acids produced by decomposition of organic matter from pine litter in O and A horizons had weathered primary minerals in A and E horizons releasing Al and Fe. Percolating waters moved the organo-metallic complexes from A and E horizons to Bhsm and Bs horizons where the complexes coated and bridged sand grains eventually forming cemented ortstein. Because of the high biotite content of the parent material, the index of accumulation of Fe and Al in the Bhsm horizon (Al + 0.5 Fe = 4.1%) was the highest reported in Spodosols of Finland. The data support the theory of downward movement of Al and Fe as organo-metallic complexes with formation of some ferrihydrite but little or no formation of imogolite type materials. Little, if any, podzolization has likely occurred since the initiation of cultivation because, after agricultural liming and consequent increase of pH in the Ap horizon, organic compounds are likely to chelate Ca and Mg rather than Al and Fe.;
Comparative study of alloxan effects in copper-loaded and iron-loaded rats: lipid peroxidation, protein oxidation, proteasome and antioxidant enzyme activities
Authors: Alexandrova Albena , Georgieva Almira , Petrov Lubomir , Tsvetanova Elina , Kirkova Margarita
Published: May 2006

The in-vivo effects of alloxan on protein oxidation and lipid peroxidation, as well as on proteasome and antioxidant enzyme activities in liver and kidney of copper-loaded and iron-loaded rats, were studied. In control animals, a single alloxan dose (120 mg/kg, i.p.) increased blood-glucose concentration at the 24th hr and 48th hr and, especially, on the 5th day. For these periods of alloxan action, no changes in lipid peroxidation and antioxidant enzyme activities were found; only a slight increase of carbonyl content and strong increase of trypsin-like proteasome activity in rat liver on the 5th day was observed. Five days after alloxan injection, the blood-glucose concentration in iron-pretreated rats was similar to that of the controls. However, it was significantly lower in copper-pretreated animals; hence, insulin-mimetic action of copper might be suggested. The lower proteasome activity, measured in liver of copper-pretreated diabetic rats is probably due to a potential copper-chelating ability of alloxan. The present results showed that the action of alloxan was different in copper-and iron-pretreated rats. Analogous studies, using pretreatment with other metals, would contribute to a further elucidation of the role of different metals in diabetes development, especially in regions with environmental metal contamination.
Targeting of solid tumors and blood malignancies by antibody-based therapies — EGFR-pathway as an example
Authors: Krzemieniecki Krzysztof , Szpyt Elzbieta , Rashedi Iran , Gawron Katarzyna , Los Marek
Published: May 2006

A well-coordinated interaction between extracellular signals and intracellular response forms the basis of life within multicellular organisms, with growth factors playing a crucial role in these interactions. Discoveries in recent years have shown that components of the Epidermal Growth Factor (EGF) signaling system have frequently been used by cancer cells to autonomously provide survival and proliferation signals. The main focus of this review is the ErbB epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases including ErbB1/EGFR, ErbB2/HER2/neu, ErbB3/HER3, and ErbB4/HER4 as therapeutic targets. Since the ErbB receptor family regulates cell proliferation through the Ras-mitogen-activated protein kinase (RAS/MAPK) pathway, and cell survival and transformation through the phosphatidylinositol 3-kinase (PI3K/AKT) pathway, pharmacological targeting of these pathways is also discussed. We will also address the clinical studies that have been conducted to evaluate antibody-based therapies mostly on solid tumors and hematologic malignancies.
Design of environmental regulatory policies for sustainable emission reduction
Authors: Malcolm Andrés , Zhang Libin , Linninger Andreas A.
Published: May 2006

Current environmental emission regulations typically follow a command‐and‐control approach mandating the installation of state‐of‐the‐art abatement technology to safeguard hard emission thresholds. However, this type of regulation offers no reward for conducting pollution prevention and technological research to reduce emissions below compliance levels through process innovation. Alternatively, market‐based regulations stimulate continued improvement of cleaner manufacturing practices by creating economic incentives for sustained waste reduction. The aim of this work is to furnish regulators and manufacturers with a concise tool for quantifying the impact of future regulatory scenarios. The proposed methodology employs realistic mathematical models of pollution abatement operations used in chemical, pharmaceutical, and specialty chemical manufacturing. It assesses the feasibility of treatment options, estimates their cost and expected emissions. Rigorous optimization techniques are introduced for managing regional emission reduction efforts at reasonable cost to manufacturers. The comprehensive mathematical programming formulations will enable plant managers to ascertain expected compliance cost, and regulators to design environmental regulations for reducing regional emissions at tolerable cost to industry. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Optical and physicochemical properties of silica‐supported TiO2photocatalysts
Authors: Marugán Javier , Van Grieken Rafael , Alfano Orlando M. , Cassano Alberto E.
Published: May 2006

Commercial applications of photocatalysis in slurry reactors employing titanium dioxide particles present the disadvantage of the additional cost associated with the downstream catalyst separation. In past years a significant effort has been made to develop supported titania photocatalysts on particles of larger size in order to facilitate the sedimentation recovery process. In this work, two different silica materials have been used for preparing immobilized catalysts. Their physicochemical characteristics have been compared with those corresponding to two commercially available unsupported titanium dioxide catalysts. However, for reaction kinetics and reactor design purposes, three additional properties must be known: (i) the spectral specific radiation absorption coefficient, (ii) the spectral specific radiation scattering coefficient, and (iii) the asymmetry factor of a model for the angular distribution of the scattered photons (the phase function). They have been determined with specially designed spectrophotometer transmission, diffuse transmittance, and diffuse reflectance experiments and constitute the most significant addition to this contribution. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Enantiomeric Separation of Fluoxetine Derivatives on Polysaccharide‐Based Chiral Columns
Authors: Yu Li , Mei‐Li Fa , Jie‐Guo Xing
Published: May 2006

A high performance liquid chromatography (HPLC) method employing amylose‐based chiral columns (Chiralpak AD‐RH and Chiralpak AD) and cellulose‐based chiral columns (Chiralcel OD) as chiral stationary phases have been developed for the enantiomeric separation of fluoxetine (FLX) derivatives. The FLX was derivatized with 4‐(N‐chloroformylmethyl‐N‐methyl)amino‐7‐nitro‐2,1,3‐benzoxadiazole (NBD‐COCl) and 4‐(N‐chloroformylmethyl‐N‐methyl)amino‐7‐N,N‐dimethylaminosulfonyl‐2,1,3‐benzoxadiazole (DBD‐COCl), respectively. Influence of the mobile phase composition and column temperature on the enantioseparation was discussed during the separation. On the basis of separation of derivatized FLX enantiomers, the paper also discussed the separation mechanism on the chiral stationary phases used.
The Square Kilometre Array: a new probe of cosmic magnetism
Authors: Gaensler B. M.
Published: May 2006

Magnetic fields are a fundamental part of many astrophysical phenomena, but the evolution, structure and origin of magnetic fields are still unresolved problems in physics and astrophysics. When and how were the first fields generated? Are present‐day magnetic fields the result of standard dynamo action, or do they represent rapid or recent field amplification through other processes? What role do magnetic fields play in turbulence, cosmic ray acceleration and structure formation? I explain how the Square Kilometre Array (SKA), a next‐generation radio telescope, can deliver stunning new data‐sets that will address these currently unanswered issues. The foundation for these experiments will be an all‐sky survey of rotation measures, in which Faraday rotation toward > 107 background sources will provide a dense grid for probing magnetism in the Milky Way, nearby galaxies, and in distant galaxies, clusters and protogalaxies. Using these data, we can map out the evolution of magnetized structures from redshifts z > 3 to the present, can distinguish between different origins for seed magnetic fields in galaxies, and can develop a detailed model of the magnetic field geometry of the intergalactic medium and of the overall Universe. In addition, the SKA will certainly discover new magnetic phenomena beyond what we can currently predict or imagine. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Primordial magnetic seeds from string cosmology
Authors: Gasperini M.
Published: May 2006

After a discussion of the inflationary production of primordial magnetic seeds and a brief review of various possible mechanisms, we concentrate on the analysis of the photon–dilaton coupling typical of string theory models. Particular attention is paid to the constraints to be imposed on the primordial seed spectrum and to the possibility of obtaining phenomenological signatures of heterotic and Type I superstrings, in principle accessible to present (or near‐future) observations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Primordial magnetic fields and CMB anisotropies
Authors: Subramanian K.
Published: May 2006

Possible signatures of primordial magnetic fields on the Cosmic Microwave Background (CMB) temperature and polarization anisotropies are reviewed. The signals that could be searched for include excess temperature anisotropies particularly at small angular scales below the Silk damping scale, B‐mode polarization, and non‐Gaussian statistics. A field at a few nG level produces temperature anisotropies at the 5 µK level, and B‐mode polarization anisotropies 10 times smaller, and is therefore potentially detectable via the CMB anisotropies. An even smaller field, with B 0 < 0.1 nG, could lead to structure formation at high redshift z > 15, and hence naturally explain an early re‐ionization of the Universe. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The growth of baryonic structure in the presence of an isotropic magnetic field
Authors: Gazzola L. , King E. , Pearce F. , Coles P.
Published: May 2006

We follow the passive evolution of magnetic fields in SPH simulations to study their role in structure formation and galaxy clusters properties. Despite magnetic fields are not dynamically important for massive objects, they can still affect the properties of group‐size objects and core regions and also affect particle's entropy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Amplification of magnetic fields by supernova‐driven turbulence
Authors: Kim J. , Balsara D. S.
Published: May 2006

Observations of μG magnetic fields in radio galaxies at cosmological epochs as early as around z = 2 have shortened the available time for dynamo action. This fact suggests that the mean‐field dynamo mechanism in a global galactic scale either is too slow to amplify a seed field generated by the Biermann battery effect to the level of the observed field strength at z ∼ 2 or needs much stronger seed fields of an order of 10–10 G. A “contamination” picture that amplified magnetic fields in smaller objects, such as stars or AGNs, within a relatively shorter timescale spread out through supernova ejecta, stellar winds, and AGN jets to nearby environments is gaining momentum. In line with this picture, we demonstrate, through three‐dimensional numerical experiments, that magnetic fields can be amplified by supernova‐driven turbulence with two orders of magnitude smaller e‐folding timescale than that of the mean‐field dynamo mechanism. Therefore, supernova‐driven turbulence may play an important role in amplifying small‐scale B ‐fields in any astrophysical systems that have harbored massive stars. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Biermann mechanism in primordial supernova remnants and seed magnetic fields
Authors: Hanayama H. , Takahashi K. , Kotake K. , Oguri M. , Ichiki K. , Ohno H.
Published: May 2006

We have studied the generation of magnetic fields by the Biermann mechanism in the pair‐instability supernovae explosions of the first stars. The Biermann mechanism produces magnetic fields in the shocked region between the bubble and interstellar medium (ISM), even if magnetic fields are absent initially. We have performed a series of two‐dimensional magnetohydrodynamic simulations with the Biermann term and estimate the amplitude and total energy of the produced magnetic fields. We .nd that magnetic fields with amplitude 10–14–10–17 G are generated inside the bubble, though the amount of magnetic fields generated depend on specific values of initial conditions. This corresponds to magnetic fields with total energy of 1028–1031 erg per each supernova remnant, which is strong enough to be the seed magnetic field for a galactic and/or interstellar dynamo. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Probing magnetohydrodynamical scenarios for jet production
Authors: de Gouveia Dal Pino E. M.
Published: May 2006

Large‐scale magnetic fields created by dynamo action along with magneto‐centrifugal and reconnection processes in accretion disks around the sources is currently the most accepted mechanism for jet production. Understanding the production of magnetic fields in jet‐accretion phenomena may be the key for understanding the origin of the large‐scale magnetic fields in galaxy clusters and in the Universe. Here, we discuss recent observational, theoretical and numerical results on jet phenomena that support the MHD scenarios for jet production. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic helicity in primordial and dynamo scenarios of galaxies
Authors: Brandenburg A.
Published: May 2006

Some common properties of helical magnetic fields in decaying and driven turbulence are discussed. These include mainly the inverse cascade that produces fields on progressively larger scales. Magnetic helicity also restricts the evolution of the large‐scale field: the field decays less rapidly than a non‐helical field, but it also saturates more slowly, i.e. on a resistive time scale if there are no magnetic helicity fluxes. The former effect is utilized in primordial field scenarios, while the latter is important for successfully explaining astrophysical dynamos that saturate faster than resistively. Dynamo action is argued to be important not only in the galactic dynamo, but also in accretion discs in active galactic nuclei and around protostars, both of which contribute to producing a strong enough seed magnetic field. Although primordial magnetic fields may be too weak to compete with these astrophysical mechanisms, such fields could perhaps still be important in producing polarization effects in the cosmic background radiation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The nonlinear galactic dynamo and magnetic helicity transport
Authors: Kleeorin N. , Moss D. , Rogachevskii I. , Sokoloff D.
Published: May 2006

We discuss nonlinear mean‐field galactic dynamo models and associate a universal mechanism for saturation of the dynamo with the transport of magnetic helicity. The crucial point for saturation of the dynamo is the existence of a non‐zero flux of magnetic helicity. We demonstrate that this saturation mechanism is quite insensitive to the form of this helicity flux. In that sense this is a robust mechanism which limits the growth of the mean magnetic field.Without this flux, the total magnetic helicity is conserved locally and the strength of the saturated mean magnetic field is very small compared to the equipartition strength. The inclusion of a flux of magnetic helicity means that the total magnetic helicity is not conserved locally because the magnetic helicity of small‐scale magnetic fluctuations is redistributed by the flux. The equilibrium state is given by a balance between magnetic helicity production and magnetic helicity transport. The equilibrium value of the galactic large‐scale magnetic field is given approximately by equipartition between the kinetic energy densities of the interstellar turbulence and the mean magnetic field.We also compare the action of algebraic and dynamic nonlinearities in the galactic dynamo. The algebraic α quenching saturates the dynamo, however a more realistic simultaneous quenching of the α effect and turbulent magnetic diffusion cannot saturate the growth of the mean magnetic field; this can only be achieved by the combined effects of algebraic and dynamic nonlinearities. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamo coefficients in Parker unstable disks with cosmic rays
Authors: Otmianowska‐Mazur K. , Kowal G. , Hanasz M.
Published: May 2006

We investigate a three‐dimensional (3D) numerical model of the Parker instability with cosmic rays and shear in a galactic disk and compute the components of the dynamo coefficients $ \hat \alpha $ and $ \hat \beta $ from the electromotive force (EMF) obtained directly from our simulations. In our model we apply well‐known statistical procedures in order to fit the modeled EMF in terms of the dynamo tensors. Nevertheless, we do not solve all problems with the physical interpretation of the dynamo tensors prescribed in the way of Rädler (1980). We find that the presented methods give us the possibility to compute the coefficients with a desired statistical quality. The obtained values of αxx (along the radial direction in a galaxy) are of order of a few km/s, while the values of αyy (along the azimuthal direction) are one order of magnitude smaller. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
From Parker and thermal instabilities to the formation of giant molecular clouds
Authors: Kosiński R. , Hanasz M.
Published: May 2006

We study the Parker instability (PI) under the influence of heating and cooling processes. We distinguish two models with different heating functions. On the base of linear stability analysis, we find that the properties of PI in such a system are significantly different with respect to the adiabatic and isothermal cases. We find that in case of thermally stable equilibrium, PI operating in presence of additional heating sources, postulated by Reynolds et al. (1999), and cooling described by Dalgarno & McCray (1972), leads to a decrease of temperature in magnetic valleys. Numerical simulations show that this behavior promotes a transition of gas to thermally unstable regime. In consequence the gas density grows up by an order of magnitude and the condensed gas clumps acquire compact shapes. Our results lead to the conclusion that PI can trigger the formation of giant molecular clouds complexes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Toruń 6‐cm polarimetry of the MilkyWay
Authors: Ryś S. , Chyży K. T. , Kus A. , Pazderski E. , Soida M. , Urbanik M.
Published: May 2006

We present first results of a radio continuum and polarization survey of the Milky Way at 4.7 GHz carried out with the 32‐m radio telescope in Toruń. The survey is much less affected by depolarization effects than previous measurements at lower frequencies. This enables the study of magnetic field structure and its interrelations with particular features in the interstellar medium to much larger distances from the Sun. Our preliminary total power map shows a good association of radio features with galactic star‐forming regions while the polarization data reveal an increasing coherence of magnetic fields away from the Galaxy's mid‐plane. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The large scale magnetic field configuration in the Sombrero galaxy – persistence during galaxy evolution?
Authors: Krause M. , Wielebinski R. , Dumke M.
Published: May 2006

Radio polarization observations at 4.86 and 8.35 GHz of the nearby edge‐on galaxy M 104 revealed a large‐scale magnetic field in this early‐type spiral. This is to our knowledge the first detection of a regular magntic field in an Sa galaxy in the radio range. The magnetic field orientation in M 104 is predominantly parallel to the disk but has also vertical components at larger z‐distances from the disk, i.e. a field configuration typical for normal edge‐on spiral galaxies. Bolometer observations at 345 GHz data pertain to the cold dust content of the galaxy. Despite the optical appearance of the object with the huge dust lane, its dust content is smaller than that of more late‐type spirals. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic field evolution in the perturbed Virgo spiral NGC 4654 – MHD 3D modeling
Authors: Soida M. , Otmianowska‐Mazur K. , Chyży K. T. , Vollmer B.
Published: May 2006

The Virgo cluster spiral galaxy NGC 4654 shows clear signs of interaction, but the nature of this interaction is still unclear. Two possibilities have been discussed: ram pressure stripping and tidal interaction with NGC 4639. Dynamical simulations speak in favor of the tidal interaction with small addition of constant ram pressure.We present synthetic polarized intensity maps calculated using 3D MHD simulations based on gas velocity field evolution. Our results are compared with recent Effelsberg 100 m telescope observations of NGC 4654. The MHD model and the observations are qualitatively similar. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evolution of magnetic fields at high redshift
Authors: Zweibel E.G.
Published: May 2006

The origin of magnetic fields in the Universe is a cosmology problem. The evolution of the field is a plasma physics problem. I review these problems and focus on magnetogenesis in accretion disks, specifically, the transition from the Biermann battery, which creates seed fields, to amplification by turbulence driven by magnetorotational instability. In collisional disks, there is a gap between the fieldstrength characteristic of the battery and the fieldstrength necessary to sustain magnetorotational instability, but in collisionless disks the transition occurs at low fieldstrength. Because collisionless disks are generally hot, and have short dynamical times, they are likely to be small. Thus, in the battery scenario, magnetic fields on large scales were built from fields created in many small sources. Simple estimates based on turbulent diffusion suggest that galaxies and the cores of galaxy clusters can be magnetized in this way, but not the intergalactic medium at large. The problem of creating a large‐scale field remains unsolved. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Probing distant magnetic fields with M82‐type galaxies
Authors: Wielebinski R.
Published: May 2006

I present the results of recent 9 mm observations of the starburst galaxy M 82 with the Effelsberg 100‐m radio telescope. The magnetic fields deduced from these observations are in good agreement with previous multifrequency VLA observations. The general pattern of azimuthal magnetic fields along the disc of the galaxy and vertical fields in the central region, as seen in most nearby galaxies, is confirmed to exist also in M 82. Since the starburst galaxy M 82 is a very powerful radio source similar objects should be visible at large distances. Possibly the distant magnetic Universe could be probed by observing sources similar to M 82 with the new generation of radio telescopes. Here the ALMA telescope holds great promise for the near future. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)