bluuebunny/crossref_metadata_2025 huggingface dataset:
MtDNA Profile of West Africa Guineans: Towards a Better Understanding of the Senegambia Region
Authors: Rosa Alexandra , Brehm António , Kivisild Toomas , Metspalu Ene , Villems Richard
Published: July 2004

The matrilineal genetic composition of 372 samples from the Republic of Guiné‐Bissau (West African coast) was studied using RFLPs and partial sequencing of the mtDNA control and coding region. The majority of the mtDNA lineages of Guineans (94%) belong to West African specific sub‐clusters of L0‐L3 haplogroups. A new L3 sub‐cluster (L3h) that is found in both eastern and western Africa is present at moderately low frequencies in Guinean populations. A non‐random distribution of haplogroups U5 in the Fula group, the U6 among the “Brame” linguistic family and M1 in the Balanta‐Djola group, suggests a correlation between the genetic and linguistic affiliation of Guinean populations. The presence of M1 in Balanta populations supports the earlier suggestion of their Sudanese origin. Haplogroups U5 and U6, on the other hand, were found to be restricted to populations that are thought to represent the descendants of a southern expansion of Berbers. Particular haplotypes, found almost exclusively in East‐African populations, were found in some ethnic groups with an oral tradition claiming Sudanese origin.
Animated Visualization of Causal Relations Through Growing 2D Geometry
Authors: Elmqvist Niklas , Tsigas Philippas
Published: July 2004

Causality visualization is an important tool for many scientific domains that involve complex interactions between multiple entities (examples include parallel and distributed systems in computer science). However, traditional visualization techniques such as Hasse diagrams are not well-suited to large system executions, and users often have difficulties answering even basic questions using them, or have to spend inordinate amounts of time to do so. In this paper, we present the Growing Squares and Growing Polygons methods, two sibling visualization techniques that were designed to solve this problem by providing efficient 2D causality visualization through the use of color, texture, and animation. Both techniques have abandoned the traditional linear timeline and instead map the time parameter to the size of geometrical primitives representing the processes; in the Growing Squares case, each process is a color-coded square that receives color influences from other process squares as messages reach it; in the Growing Polygons case, each process is instead an n-sided polygon consisting of triangular sectors showing color-coded influences from the other processes. We have performed user studies of both techniques, comparing them with Hasse diagrams, and they have been shown to be significantly more efficient than old techniques, both in terms of objective performance as well as the subjective opinion of the test subjects (the Growing Squares technique is, however, only significantly more efficient for small systems).
Characteristics of a plasma sheath in a radio frequency biased voltage
Authors: Zhang Yu , Liu Jinyuan , Liu Yue , Wang X.
Published: July 2004

The exact equations of a radio frequency (rf) sheath driven by rf-biased voltage are solved numerically. All of the sheath characteristics for an arbitrary rf frequency are obtained, including the time-dependent ion density distributions, the ion current density, and ion kinetic energy at the electrode. Moreover, the ion energy distributions (IEDs) impinging on the rf-biased electrode are calculated, which match the experiment result [M. A. Sobolewski, J. K. Olthoff, and Y. C. Wang, J. Appl. Phys. 85, 3966 (1999)] exactly. The results show that the rf frequency is a crucial parameter for determining the spatiotemporal characteristic and the shape of IEDs.
Symmetry of matrix-valued stochastic processes and noncolliding diffusion particle systems
Authors: Katori Makoto , Tanemura Hideki
Published: July 2004

As an extension of the theory of Dyson’s Brownian motion models for the standard Gaussian random-matrix ensembles, we report a systematic study of Hermitian matrix-valued processes and their eigenvalue processes associated with the chiral and nonstandard random-matrix ensembles. In addition to the noncolliding Brownian motions, we introduce a one-parameter family of temporally homogeneous noncolliding systems of the Bessel processes and a two-parameter family of temporally inhomogeneous noncolliding systems of Yor’s generalized meanders and show that all of the ten classes of eigenvalue statistics in the Altland–Zirnbauer classification are realized as particle distributions in the special cases of these diffusion particle systems. As a corollary of each equivalence in distribution of a temporally inhomogeneous eigenvalue process and a noncolliding diffusion process, a stochastic-calculus proof of a version of the Harish–Chandra (Itzykson–Zuber) formula of integral over unitary group is established.
Effects of high density peaking and high collisionality on the stabilization of the electrostatic turbulence in the Frascati Tokamak Upgrade
Authors: Romanelli M. , Bourdelle C. , Dorland W.
Published: July 2004

Experiments carried out on the Frascati Tokamak Upgrade (FTU) [B. Angelini et al., Nucl. Fusion 43, 1632 (2003)] with the injection of deuterium pellets in ohmic, high density plasmas show that a remarkable enhancement of the energy confinement time is achieved when the pellet penetrates deeply in the plasma core. Here a study of pellet effects on the electrostatic turbulence is carried out with the gyrokinetic codes Kinezero [C. Bourdelle et al., Nucl. Fusion 42, 892 (2002)] and GS2 [M. Kotschenreuther, G. Rewoldt, and M. W. Tang, Comput. Phys. Commun. 88, 128 (1995)]. The analysis shows that the collisionality of FTU plasmas is high enough to detrap the electrons. The low wavelength unstable modes remaining are then pure ion temperature gradient modes that are stabilized by more peaked density profiles. In the postpellet phase the density peaking stabilizes also strongly the high wavelength electron temperature gradient modes.
Wave patterns of a rivulet of surfactant solution in a Hele-Shaw cell
Authors: Drenckhan W. , Gatz S. , Weaire D.
Published: July 2004

When a stream of surfactant solution is injected at a constant rate between two narrowly spaced, vertical glass plates, the straight rivulet becomes unstable at a critical flow rate. Various regimes are encountered, in which upward and downward traveling waves of remarkable regularity are observed. We present extensive data for these waves and some tentative theory to account for some of their properties.
High-frequency electron beam modulation by a ferroelectric cathode with anomalous plasma resistance
Authors: Chirko K. , Gurovich V. Ts. , Krasik Ya. E. , Peleg O. , Felsteiner J. , Bernshtam V.
Published: July 2004

Spectroscopic measurements are reported of the plasma formed inside a cathode having a ferroelectric source incorporated in it. These measurements were performed during the generation of a high-frequency modulated electron beam in a planar diode with the above cathode. It was found that there is a spatially periodic structure in the plasma density, electric field, and electron energy in the plasma in the longitudinal direction from the ferroelectric surface. The plasma density, electric field, and electron energy vary in the range of 5×1013–5×1014 cm−3, 0–1 kV/cm, and 2–30 eV, respectively. Also, it was found that the plasma electron temperature is ∼8 eV in the vicinity of the ferroelectric surface and ∼2 eV in the bulk of the plasma. To explain the obtained experimental data a qualitative model is suggested. The model is based on fast periodic appearance of anomalous plasma resistance due to generation of ion-acoustic instability. The latter is controlled by the ratio between the velocities of the current carrying electrons and the ion sound. Computer simulations show good agreement with the experimentally obtained data.
Emotion Perception from Dynamic and Static Body Expressions in Point-Light and Full-Light Displays
Authors: Atkinson Anthony P , Dittrich Winand H , Gemmell Andrew J , Young Andrew W
Published: July 2004

Research on emotion recognition has been dominated by studies of photographs of facial expressions. A full understanding of emotion perception and its neural substrate will require investigations that employ dynamic displays and means of expression other than the face. Our aims were: (i) to develop a set of dynamic and static whole-body expressions of basic emotions for systematic investigations of clinical populations, and for use in functional-imaging studies; (ii) to assess forced-choice emotion-classification performance with these stimuli relative to the results of previous studies; and (iii) to test the hypotheses that more exaggerated whole-body movements would produce (a) more accurate emotion classification and (b) higher ratings of emotional intensity. Ten actors portrayed 5 emotions (anger, disgust, fear, happiness, and sadness) at 3 levels of exaggeration, with their faces covered. Two identical sets of 150 emotion portrayals (full-light and point-light) were created from the same digital footage, along with corresponding static images of the ‘peak’ of each emotion portrayal. Recognition tasks confirmed previous findings that basic emotions are readily identifiable from body movements, even when static form information is minimised by use of point-light displays, and that full-light and even point-light displays can convey identifiable emotions, though rather less efficiently than dynamic displays. Recognition success differed for individual emotions, corroborating earlier results about the importance of distinguishing differences in movement characteristics for different emotional expressions. The patterns of misclassifications were in keeping with earlier findings on emotional clustering. Exaggeration of body movement (a) enhanced recognition accuracy, especially for the dynamic point-light displays, but notably not for sadness, and (b) produced higher emotional-intensity ratings, regardless of lighting condition, for movies but to a lesser extent for stills, indicating that intensity judgments of body gestures rely more on movement (or form-from-movement) than static form information.
Visual Guidance of Intercepting a Moving Target on Foot
Authors: Fajen Brett R , Warren William H
Published: July 2004

How do people walk to a moving target, and what visual information do they use to do so? Under a pursuit strategy, one would head toward the target's current position, whereas under an interception strategy, one would lead the target, ideally by maintaining a constant target-heading angle (or constant bearing angle). Either strategy may be guided by the egocentric direction of the target, local optic flow from the target, or global optic flow from the background. In four experiments, participants walked through a virtual environment to reach a target moving at a constant velocity. Regardless of the initial conditions, they walked ahead of the target for most of a trial at a fairly constant speed, consistent with an interception strategy (experiment 1). This behavior can be explained by trying to maintain a constant target-heading angle while trying to walk a straight path, with transient steering dynamics. In contrast to previous results for stationary targets, manipulation of the local optic flow from the target (experiment 2) and the global optic flow of the background (experiments 3 and 4) failed to influence interception behavior. Relative motion between the target and the background did affect the path slightly, presumably owing to its effect on perceived target motion. We conclude that humans use an interception strategy based on the egocentric direction of a moving target.
Basic Atmospheric Chemistry: A Quantum Chemical Study on Hydration of Mesospheric NaOH
Authors: Petrie Simon
Published: July 2004

Environmental Context.A natural global layer of sodium atoms exists in the mesosphere, 80–95 km above sea level, where it originates—along with lithium, iron, and calcium—from ablation of meteors. Sodium, as its hydroxide, readily associates with free water to form NaOH·(H2O)n clusters. The clusters strongly emit IR radiation and may therefore affect the upper atmosphere’s temperature profile; the clusters are also likely to be a source of nuclei for noctilucent clouds. The same NaOH-based processes may also occur at lower altitudes in the troposphere where water is more abundant than carbon dioxide.

Abstract.The sequential association of water molecules with NaOH, a key upper-atmosphere metal-containing molecule, is investigated using quantum chemical calculations. The first several H2O–NaOH·(H2O)n–1 bond strengths are sizeable (respectively 82, 70, 56, 42, 42, and 36 kJ mol–1 according to calculations), suggesting that the termolecular association reactions of NaOH·(H2O)n–1 with H2O may well be efficient upper-atmospheric processes. Such reactions would provide an alternative or additional pathway to the production of hydrated sodium bicarbonate, which has been implicated in the nucleation of noctilucent clouds. The NaOH·(H2O)n complexes are also characterized by very large IR intensities across the 3–5 μm wavelength range, suggesting that they may contribute disproportionately to the IR emission profile of the upper atmosphere.
The Correlation Pattern of Fly Ash Components: Chromium as a Potential Catalyst in the Thermal Formation of Chlorinated Aromatic Compounds
Authors: Öberg Tomas , Öhrström Tomas , Bergström Jan
Published: July 2004

Environmental Context.Harmful chlorinated aromatic molecules are often formed and released into the environment during incineration of municipal waste and other waste fuels. This is a problem that has been known since the 1970s, and while efforts are being made to reduce these emissions, these persistent organic pollutants are still subsequently released into the environment, with residues and emissions to the atmosphere. In an attempt to uncover the chemical agents responsible for the formation of these pollutants, this study reveals that chromium, a commonly encountered metal, could be an important factor. Abstract.Chlorinated aromatic compounds are unintentionally released from combustion sources into the environment. This thermal formation is catalyzed by fly ash components and much interest has been focussed on the role of copper. This study report results from a series of 16 full-scale trials with different fuel compositions. The correlation pattern of fly ash components seem to suggest that the catalytic effect may be due also to other metal oxychlorination catalysts. Chromium shows particularly strong and statistically significant correlations with many of the chlorinated phenols, benzenes, dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs).
Paracetamol Mineralization by Advanced Electrochemical Oxidation Processes for Wastewater Treatment
Authors: Sirés Ignasi , Arias Conchita , Cabot Pere Lluís , Centellas Francesc , Rodríguez Rosa María , Garrido José Antonio , Brillas Enric
Published: July 2004

Environmental Context.Even after passing through water treatment plants, discarded pharmaceuticals have been linked with poisoning aquatic life. A simple and reliable method for treating household wastewater would alleviate this issue. Using the common pain reliever paracetamol as a model, the simple combination of dissolved iron and copper with ultraviolet light is shown to fully decompose (‘mineralize’) this drug into simple inorganic components, which represents an improvement over current treatments with ozone or peroxides, that achieve only partial mineralization.

Abstract.Paracetamol solutions at pH 3.0 have been efficiently mineralized by environmentally clean electrochemical methods such as electro-Fenton and photoelectro-Fenton processes using a cell with a Pt anode and an O2-diffusion cathode for H2O2 electrogeneration. This species reacts with added Fe2+ giving hydroxyl radical as main oxidant. Photoelectro-Fenton with Fe2+, Cu2+, and UVA light as catalysts leads to complete mineralization due to the removal of the final carboxylic acids (oxalic and oxamic). When catalysts are used separately, both acids or part of them remain in solution, giving a partial (> 65%) mineralization.
The crystal structure of human endonuclease VIII-like 1 (NEIL1) reveals a zincless finger motif required for glycosylase activity
Authors: Doublié Sylvie , Bandaru Viswanath , Bond Jeffrey P. , Wallace Susan S.
Published: July 2004

In prokaryotes, two DNA glycosylases recognize and excise oxidized pyrimidines: endonuclease III (Nth) and endonuclease VIII (Nei). The oxidized purine 8-oxoguanine, on the other hand, is recognized by Fpg (also known as MutM), a glycosylase that belongs to the same family as Nei. The recent availability of the human genome sequence allowed the identification of three human homologs of
Escherichia coli
Nei. We report here the crystal structure of a human Nei-like (NEIL) enzyme, NEIL1. The structure of NEIL1 exhibits the same overall fold as
E. coli
Nei, albeit with an unexpected twist. Sequence alignments had predicted that NEIL1 would lack a zinc finger, and it was therefore expected to use a different DNA-binding motif instead. Our structure revealed that, to the contrary, NEIL1 contains a structural motif composed of two antiparallel β-strands that mimics the antiparallel β-hairpin zinc finger found in other Fpg/Nei family members but lacks the loops that harbor the zinc-binding residues and, therefore, does not coordinate zinc. This “zincless finger” appears to be required for NEIL1 activity, because mutating a very highly conserved arginine within this motif greatly reduces the glycosylase activity of the enzyme.
A family of Acrp30/adiponectin structural and functional paralogs
Authors: Wong Guang W. , Wang Jin , Hug Christopher , Tsao Tsu-Shuen , Lodish Harvey F.
Published: July 2004

Biochemical, genetic, and animal studies in recent years have established a critical role for the adipokine Acrp30/adiponectin in controlling whole-body metabolism, particularly by enhancing insulin sensitivity in muscle and liver, and by increasing fatty acid oxidation in muscle. We describe a widely expressed and highly conserved family of adiponectin paralogs designated as C1q/tumor necrosis factor-α-related proteins (CTRPs) 1–7. In the present study, we focus on mCTRP2, the mouse paralog most similar to adiponectin. At nanomolar concentrations, bacterially produced mCTRP2 rapidly induced phosphorylation of AMP-activated protein kinase, acetyl-CoA carboxylase, and mitogen-activated protein kinase in C2C12 myotubes, which resulted in increased glycogen accumulation and fatty acid oxidation. The discovery of a family of adiponectin paralogs has implications for understanding the control of energy homeostasis and could provide new targets for pharmacologic intervention in metabolic diseases such as diabetes and obesity.
A Role forSaccharomyces cerevisiaeChk1p in the Response to Replication Blocks
Authors: Schollaert Kaila L. , Poisson Julie M. , Searle Jennifer S. , Schwanekamp Jennifer A. , Tomlinson Craig R. , Sanchez Yolanda
Published: July 2004

Replication blocks and DNA damage incurred during S phase activate the S-phase and intra-S-phase checkpoint responses, respectively, regulated by the Atrp and Chk1p checkpoint kinases in metazoans. In Saccharomyces cerevisiae, these checkpoints are regulated by the Atrp homologue Mec1p and the kinase Rad53p. A conserved role of these checkpoints is to block mitotic progression until DNA replication and repair are completed. In S. cerevisiae, these checkpoints include a transcriptional response regulated by the kinase Dun1p; however, dun1Δ cells are proficient for the S-phase-checkpoint-induced anaphase block. Yeast Chk1p kinase regulates the metaphase-to-anaphase transition in the DNA-damage checkpoint pathway via securin (Pds1p) phosphorylation. However, like Dun1p, yeast Chk1p is not required for the S-phase-checkpoint-induced anaphase block. Here we report that Chk1p has a role in the intra-S-phase checkpoint activated when yeast cells replicate their DNA in the presence of low concentrations of hydroxyurea (HU). Chk1p was modified and Pds1p was transiently phosphorylated in this response. Cells lacking Dun1p were dependent on Chk1p for survival in HU, and chk1Δ dun1Δ cells were defective in the recovery from replication interference caused by transient HU exposure. These studies establish a relationship between the S-phase and DNA-damage checkpoint pathways in S. cerevisiae and suggest that at least in some genetic backgrounds, the Chk1p/securin pathway is required for the recovery from stalled or collapsed replication forks.
Computational prediction of RNA editing sites
Authors: Bundschuh R.
Published: July 2004

Motivation: Some organisms edit their messenger RNA resulting in differences between the genomic sequence for a gene and the corresponding messenger RNA sequence. This difference complicates experimental and computational attempts to find and study genes in organisms with RNA editing even if the full genomic sequence is known. Nevertheless, knowledge of these editing sites is crucial for understanding the editing machinery of these organisms.

Results: We present a computational technique that predicts the position of editing sites in the genomic sequence. It uses a statistical approach drawing on the protein sequences of related genes and general features of editing sites of the organism. We apply the method to the mitochondrion of the slime mold Physarum polycephalum. It correctly predicts over 90% of the amino acids and over 70% of the editing sites.

Availability: The source code is available upon request from the author.
Assessing the Relationship Between Locus of Control and Social Competence in Pediatric Burn Survivors Attending Summer Camp
Authors: Piazza-Waggoner Carrie , Butcher Michelle , Adams Christina D. , Goldfarb I. W. , Slater Harvey
Published: July 2004

Previous research suggests that children with burn injuries often exhibit psychological and social difficulties. The areas of functioning that are affected most often include level of anxiety, social competence, and self-esteem. Those children having an internal locus of control (LOC) have been shown to react more positively to physical disorders and to have better psychological responding in nonburn populations. The purpose of this study was to determine whether there is a relationship between LOC and social competence in pediatric burn survivors. Participants were children aged 8 to 18 years who had been treated for a burn injury and attended a 1-week summer camp for pediatric burn survivors. Results indicated that the type of LOC was not a predictor of the overall level of social competence, as reported on three different measures of social competence. However, LOC significantly accounted for variability in the child's cooperation level, according to parent report. Other results are discussed, as well as implications for future research and clinical work in this area.
Early-Onset Unilateral Electric Cataract: A Rare Clinical Entity
Authors: Mutlu Fatih Mehmet , Duman Haluk , Çİl Yakup
Published: July 2004

Electrical injury may result in cataracts, which usually occur bilaterally. In this report, we present a rare complication of such an injury presenting as a unilateral cataract in a 33-year-old woman with a painless but gradual worsening of vision in her left eye 3 weeks after sustaining a high-voltage electrical injury. A cataract did not develop in the right eye during 26 months of follow-up. The patient underwent successful cataract surgery with an excellent return of vision. Electrical injuries may result in the formation of a unilateral cataract and therefore an ophthalmic examination should be performed regularly in the early recovery period of such injuries. Cataract surgery with intraocular lens implantation results in an excellent return of vision in patients with electrical cataract who do not have any other ocular damage.
Saturday-Morning Television: Do Sponsors Promote High-Risk Behavior for Burn Injury?
Authors: Palmieri Tina L. , Aoki Traci , Combs Elena , Curri Terese , Garma Sylvia , Kaulkin Cammie , Lawless Mary Beth , Nelson Kate , Sanders Johanna , Warden Nancy , Greenhalgh David G.
Published: July 2004

Television has become an important tool for learning and socialization in children. Although television violence has been associated with adverse effects, data on depiction of fire and burn injury are lacking. We sought to determine whether Saturday-morning television programming, viewed primarily by children, depicts fire and burn injury as safe or without consequence, thus potentially increasing the incidence of burn injury in children. This was a prospective observational study. Saturday-morning children's television programs were videotaped from 7 AM to 11 AM for eight different television networks during a 6-month period. Tapes were scored for scenes depicting fire or smoke by independent observers. Recorded items included show category, scene type, gender target, context of fire, and outcome after exposure to flame. Fire events were documented during programs and their associated commercials. A total of 108 hours of children's programs, 16 hours per network, were recorded. Scenes depicting fire or smoke were identified 1960 times, with 39% of events occurring during the program itself and 61% in commercials. Fire was depicted as either safe or without consequence in 64% of incidents. Action adventure stories accounted for 56% of flame depictions. Overall, one incident involving flame and fire was portrayed for each 3 minutes of television programming. Saturday-morning television programming frequently depicts fire as safe, empowering, or exciting. The incidence of flame use in programming varies between stations but is most prevalent in action/adventure stories. Television commercials, although brief, provide the majority of the misinformation regarding fire. Medical professional societies should alert the public to this potential hazard and recommend responsible portrayal of fire in children's television programming.
Germ cell aneuploidy in zebrafish with mutations in the mitotic checkpoint gene mps1
Authors: Poss Kenneth D. , Nechiporuk Alex , Stringer Keith F. , Lee Charles , Keating Mark T.
Published: July 2004

Aneuploidy, resulting from chromosome missegregation during meiosis, is a major cause of human infertility and birth defects. However, its molecular basis remains incompletely understood. Here we have identified a spectrum of chromosome anomalies in embryos of zebrafish homozygous for a hypomorphic mutation in Mps1, a kinase required for the mitotic checkpoint. These aneuploidies are caused by meiotic error and result in severe developmental defects. Our results reveal Mps1 as a critical regulator of chromosome number in zebrafish, and demonstrate how slight genetic perturbation of a mitotic checkpoint factor can dramatically reduce the fidelity of chromosome segregation during vertebrate meiosis.
U2AF homology motifs: protein recognition in the RRM world
Authors: Kielkopf Clara L. , Lücke Stephan , Green Michael R.
Published: July 2004

Recent structures of the heterodimeric splicing factor U2 snRNP auxiliary factor (U2AF) have revealed two unexpected examples of RNA recognition motif (RRM)-like domains with specialized features for protein recognition. These unusual RRMs, called U2AF homology motifs (UHMs), represent a novel class of protein recognition motifs. Defining a set of rules to distinguish traditional RRMs from UHMs is key to identifying novel UHM family members. Here we review the critical sequence features necessary to mediate protein–UHM interactions, and perform comprehensive database searches to identify new members of the UHM family. The resulting implications for the functional and evolutionary relationships among candidate UHM family members are discussed.
Distinct roles for Argonaute proteins in small RNA-directed RNA cleavage pathways
Authors: Okamura Katsutomo , Ishizuka Akira , Siomi Haruhiko , Siomi Mikiko C.
Published: July 2004

In mammalian cells, both microRNAs (miRNAs) and small interfering RNAs (siRNAs) are thought to be loaded into the same RNA-induced silencing complex (RISC), where they guide mRNA degradation or translation silencing depending on the complementarity of the target. In Drosophila, Argonaute2 (AGO2) was identified as part of the RISC complex. Here we show that AGO2 is an essential component for siRNA-directed RNA interference (RNAi) response and is required for the unwinding of siRNA duplex and in consequence assembly of siRNA into RISC in Drosophila embryos. However, Drosophila embryos lacking AGO2, which are siRNA-directed RNAi-defective, are still capable of miRNA-directed target RNA cleavage. In contrast, Argonaute1 (AGO1), another Argonaute protein in fly, which is dispensable for siRNA-directed target RNA cleavage, is required for mature miRNA production that impacts on miRNA-directed RNA cleavage. The association of AGO1 with Dicer-1 and pre-miRNA also suggests that AGO1 is involved in miRNA biogenesis. Our findings show that distinct Argonaute proteins act at different steps of the small RNA silencing mechanism and suggest that there are inherent differences between siRNA-initiated RISCs and miRNA-initiated RISCs in Drosophila.
Conserved MYC transcription factors play a key role in jasmonate signaling both in tomato and Arabidopsis
Authors: Boter Marta , Ruíz-Rivero Omar , Abdeen Ashraf , Prat Salomé
Published: July 2004

Jasmonates (JA) are important regulators of plant defense responses that activate expression of many wound-induced genes including the tomato proteinase inhibitor II (pin2) and leucine aminopeptidase (LAP) genes. Elements required for JA induction of the LAP gene are all present in the -317 to -78 proximal promoter region. Using yeast one-hybrid screening, we have identified the bHLH-leu zipper JAMYC2 and JAMYC10 proteins, specifically recognizing a T/G-box AACGTG motif in this promoter fragment. Mutation of the G-box element decreases JA-responsive LAP promoter expression. Expression of JAMYC2 and JAMYC10 is induced by JA, with a kinetics that precedes that of the LAP or pin2 transcripts. JAMYC overexpression enhanced JA-induced expression of these defense genes in potato, but did not result in constitutive transcript accumulation. Using footprinting assays, an additional protected element was identified, located directly adjacent to the T/G-box motif. Mutation of this element abolishes JA response, showing that recognition of this duplicated element is also required for gene expression. Knockout mutants in the AtMYC2 homolog gene of Arabidopsis are insensitive to JA and exhibit a decreased activation of the JA-responsive genes AtVSP and JR1. Activation of the PDF1.2 and b-CHI, ethylene/JA-responsive genes, is, however, increased in these mutants. These results show that the JAMYC/AtMYC2 transcription factors function as members of a MYC-based regulatory system conserved in dicotyledonous plants with a key role in JA-induced defense gene activation.
The mouse homeobox gene Not is required for caudal notochord development and affected by the truncate mutation
Authors: Ben Abdelkhalek Hanaa , Beckers Anja , Schuster-Gossler Karin , Pavlova Maria N. , Burkhardt Hannelore , Lickert Heiko , Rossant Janet , Reinhardt Richard , Schalkwyk Leonard C. , Müller Ines , Herrmann Bernhard G. , Ceolin Marcelo , Rivera-Pomar Rolando , Gossler Achim
Published: July 2004

The floating head (flh) gene in zebrafish encodes a homeodomain protein, which is essential for notochord formation along the entire body axis. flh orthologs, termed Not genes, have been isolated from chick and Xenopus, but no mammalian ortholog has yet been identified. Truncate (tc) is an autosomal recessive mutation in mouse that specifically disrupts the development of the caudal notochord. Here, we demonstrate that truncate arose by a mutation in the mouse Not gene. The truncate allele (Nottc) contains a point mutation in the homeobox of Not that changes a conserved Phenylalanine residue in helix 1 to a Cysteine (F20C), and significantly destabilizes the homeodomain. Reversion of F20C in one allele of homozygous tc embryonic stem (ES) cells is sufficient to restore normal notochord formation in completely ES cell-derived embryos. We have generated a targeted mutation of Not by replacing most of the Not coding sequence, including the homeobox with the eGFP gene. The phenotype of NoteGFP/eGFP, NoteGFP/tc, and Nottc/tc embryos is very similar but slightly more severe in NoteGFP/eGFP than in Nottc/tc embryos. This confirms allelism of truncate and Not, and indicates that tc is not a complete null allele. Not expression is abolished in Foxa2 and T mutant embryos, suggesting that Not acts downstream of both genes during notochord development. This is in contrast to zebrafish embryos, in which flh interacts with ntl (zebrafish T) in a regulatory loop and is essential for development of the entire notochord, and suggests that different genetic control circuits act in different vertebrate species during notochord formation.
An Arabidopsis Homolog of the Bacterial Cell Division Inhibitor SulA Is Involved in Plastid Division[W]
Authors: Raynaud Ceécile , Cassier-Chauvat Corinne , Perennes Claudette , Bergounioux Catherine
Published: July 2004

Plastids have evolved from an endosymbiosis between a cyanobacterial symbiont and a eukaryotic host cell. Their division is mediated both by proteins of the host cell and conserved bacterial division proteins. Here, we identified a new component of the plastid division machinery, Arabidopsis thaliana SulA. Disruption of its cyanobacterial homolog (SSulA) in Synechocystis and overexpression of an AtSulA-green fluorescent protein fusion in Arabidopsis demonstrate that these genes are involved in cell and plastid division, respectively. Overexpression of AtSulA inhibits plastid division in planta but rescues plastid division defects caused by overexpression of AtFtsZ1-1 and AtFtsZ2-1, demonstrating that its role in plastid division may involve an interaction with AtFtsZ1-1 and AtFtsZ2-1.
Creating a core journal collection for agricultural research in Tanzania: citation analysis and user opinion techniques
Authors: Dulle F.W. , Lwehabura M.J.F. , Matovelo D.S. , Mulimila R.T.
Published: July 2004

The major objective of this study was to analyse the citation patterns of agricultural scientists in Tanzania. The specific objectives were to: assess researchers’ access to information as reflected from citation analysis; establish a list of core agricultural journals for agricultural researchers in Tanzania using citation analysis and user opinions; and find out the extent to which the available information resources meet the research needs revealed by the study. The study involved the analysis of 295 MSc theses and 21 PhD theses submitted at Sokoine University of Agriculture between 1989‐1999, and 309 conference proceeding articles published during the same period. It is concluded that generally agricultural scientists in the country had limited access to current journals. A number of options are recommended to alleviate the situation, with a focus on electronic journal provision supported by international organisations.
Assessing the organizational climate and contractual relationship for perceptions of support for innovation
Authors: Lloréns Montes Francisco Javier , Ruiz Moreno Antonia , Miguel Molina Fernández Luis
Published: July 2004

The aim of this paper is to study the relationship between organizational climate and perceptions of support for innovation, considering that the relationship may be moderated by the type of labor contract the employees have. This moderating effect may have its origins in the perception of reality and the type of knowledge applied on the job. The results drawn from empirical research among 312 observations of the employees in 80 offices of a Spanish financial company enable us to verify, on the one hand, that an organizational climate characterized by support, cohesion and intrinsic recognition favors perceptions of support for innovation; and, on the other hand, that there are differences in the dimensions of climate that favor perceptions of support for innovation depending on the employees' contractual relationship with the organization.
Temporary employment and technical efficiency in Spain
Authors: Angeles Diaz‐Mayans Maria , Sanchez Rosario
Published: July 2004

Analyses how the high proportion of temporary employment affects the firm's technical efficiency. Uses the stochastic frontier approach to measure the technical efficiency of the Spanish manufacturing firms during the period 1990‐2001. A negative relation between technical efficiency and the proportion of temporary jobs has been obtained. Also, shows that permanent employment makes an important contribution to output while temporary does not.
The role of personal networks in the development of industry standards: a case study of 3G mobile telephony
Authors: Grundström Christina , Wilkinson Ian F.
Published: July 2004

Industry standards affect the diffusion and adoption of new technology and the competitiveness of individual players but their development is not under the direct control of individual actors. Examines the role and importance of personal networks in the development of industry standards on the basis of a case study of Ericsson’s involvement in the development of standards for 3G mobile telephony. Notes how relations among parties and many types of forums stemming from previous development and marketing involvement affect the complex set of interactions shape the bottom‐up self‐organizing way in which standards emerge. The case study has implications for our understanding of the way standards develop and for managers attempting to influence the outcomes.
A European perspective on the revolutionary school of management
Authors: Adcroft Andrew , Willis Robert , Clarke‐Hill Colin
Published: July 2004

The current obsession with globalization and technological change has given rise to a new school of management, the revolutionary school. This school uses language appropriated from the political concept of revolution and argues that the key role of management is the transformation of their organizations. The article considers the extent to which the European business environment has been transformed and the extent to which transformation is possible under difficult market conditions such as those faced by the European car industry. The article concludes that under the structural conditions of saturation and slow or cyclical growth, organizational transformation is unlikely to be successful.
Knowledge management is dead: long live records management
Authors: Tombs Kenneth
Published: July 2004

States that, for over a decade, knowledge management (KM) has been viewed as the way forward for information management and that it has become associated with Internet technology. Reveals that experience showed that KM projects were too often attempts by information communication technology (ICT) departments to prove that they understood how information was used by their businesses when in fact and they did not. Proposes that KM did not achieve what it set out to do because it is expensive and is not functionally straightforward, creating poorly understood operational problems. Concludes that records management is now emerging as the preferred tool for information storage because it is easily understood by all, relatively low cost, highly adaptable and low in staffing costs.
Mitigating supply chain risk through improved confidence
Authors: Christopher Martin , Lee Hau
Published: July 2004

Today's marketplace is characterised by turbulence and uncertainty. Market turbulence has tended to increase for a number of reasons. Demand in almost every industrial sector seems to be more volatile than was the case in the past. Product and technology life‐cycles have shortened significantly and competitive product introductions make life‐cycle demand difficult to predict. At the same time the vulnerability of supply chains to disturbance or disruption has increased. It is not only the effect of external events such as wars, strikes or terrorist attacks, but also the impact of changes in business strategy. Many companies have experienced a change in their supply chain risk profile as a result of changes in their business models, for example the adoption of “lean” practices, the move to outsourcing and a general tendency to reduce the size of the supplier base. This paper suggests that one key element in any strategy designed to mitigate supply chain risk is improved “end‐to‐end” visibility. It is argued that supply chain “confidence” will increase in proportion to the quality of supply chain information.
Effect of price on the diffusion of cellular subscriptions in Finland
Authors: Karine Eeva‐Mari , Frank Lauri , Laine Kalle
Published: July 2004

The aim of this study is to find out the effect of pricing on the diffusion of cellular subscriptions in Finland. There is a lack of studies on the effect of (telecommunications) service pricing on its diffusion. In the present study, a modified logistic model is applied for estimating the impact of price on the diffusion. The effect of cellular tariffs and cellular phone prices on the market potential and the diffusion rate are evaluated. Whereas almost all previous studies focusing on durables suggest that price affects either the market potential or the diffusion rate, the results of this study indicate that cellular call tariffs and cellular phone prices are not significant predictors of diffusion of cellular subscriptions. It is thus concluded that the logistic diffusion model might implicitly capture the somewhat constant price decline of cellular communications.
Information literacy for primary sources: creating a new paradigm for archival researcher education
Authors: Yakel Elizabeth
Published: July 2004

Educating researchers on how to use archival and manuscript materials and repositories is an important component in any records program. This is more important now that increasing amounts of information concerning archives and manuscripts appear daily on the web. Twenty years ago, all use of archives and manuscripts was mediated by reference personnel. This is not true today. However, the archivists' paradigm for educating researchers has not shifted accordingly. Furthermore, archivists do not have the defined basic competencies that might comprise “information literacy for primary sources”.
Retrieval features for online databases: common, unique, and expected
Authors: Othman Roslina , Sahlawaty Halim Nor
Published: July 2004

The aims of this study were to identify the retrieval features for online databases; difficulties faced by users; and retrieval features expected by users. A total of 25 databases were surveyed and 40 users were interviewed after the training sessions. Common retrieval features included Boolean operators, phrase searching, match of exact words or phrases, field specific and limit fields searches, truncation, and wildcard. Even though features are offered in many systems, their interpretation and implementation are different. Unique features included lateral searching, density and frequency of terms, reference link, and searching via table of content. The expected features included relevance feedback and term weighting other than those already offered by ACM Digital Library and IEEE Xplore. Such expectations were influenced by the users' background in ICT. Difficulties included application of the retrieval features in searching. Database providers must include the expected features, synonyms linked to terms in the thesaurus, and extensive search examples.
A Heteroskedastic Multivariate Tobit Analysis of Price Dynamics in the Presence of Price Floors
Authors: Chavas Jean‐Paul , Kim Kwansoo
Published: July 2004

This article presents an econometric analysis of the effects of price floors on price dynamics and price volatility in a multimarket context. We investigate the implications of a government price‐support program providing a censoring mechanism to the price determination process. The analysis uses a dynamic multivariate Tobit model under time‐varying volatility. The model is applied to the U.S. dairy markets with a special focus on the effects of government price‐support programs in a period of market liberalization. The econometric analysis provides useful information on the multimarket effects of price supports on price dynamics and price volatility.
Entry, Exit, and Farm Size: Assessing an Experiment in Dairy Price Policy
Authors: Foltz Jeremy D.
Published: July 2004

This article models and estimates the forces behind farm exits and changes in herd‐size among Connecticut dairy farms under the New England Dairy Compact. A model of sunk costs and farm capital investment is used to specify two econometric estimations: a random effects probit model of farm entry and exit and an autocorrelated generalized least squares panel data model of farm size. The Dairy Compact's price strategy reduced farm exits and moderately increased cow numbers. In contrast, development pressures and historically low unemployment rates increased farm exits.
Allopregnanolone Analogs That Positively Modulate GABAA Receptors Protect against Partial Seizures Induced by 6‐Hz Electrical Stimulation in Mice
Authors: Kaminski Rafal M. , Livingood Matthew R. , Rogawski Michael A.
Published: July 2004

Summary:  Purpose: Low‐frequency (6 Hz), long‐duration (3 s) electrical stimulation in mice produces seizures characterized by immobility, focal clonus, and automatic behaviors reminiscent of human limbic epilepsy. Renewed interest has been expressed in this seizure model with the recognition that it is sensitive to a broad spectrum of anticonvulsants (AEDs) and may have distinct pharmacologic responsiveness from other in vivo tests of AED efficacy. Here we sought to determine whether the progesterone‐derived neuroactive steroid allopregnanolone (5α,3α‐P) and several structural analogues with varying degrees of activity as positive allosteric modulators of γ‐aminobutyric acid (GABA)A receptors are protective in the 6‐Hz seizure model.

Methods: Mice were pretreated with neuroactive steroids (15 min before) or clonazepam (CZP; 30 min before) to 6‐Hz corneal stimulation (32 mA). Animals that failed to exhibit immobility were considered protected.

Results: The neuroactive steroids prevented 6‐Hz seizures with rank order of potencies (ED50 values): ganaxolone (6.3 mg/kg) > 5α,3α‐P (14.2 mg/kg) ≥ 5β,3α‐P (14.4 mg/kg) > 5α,3β‐P (>100 mg/kg). CZP also was protective (ED50 value, 0.075 mg/kg). The potencies of the neuroactive steroids and CZP are similar to their previously reported activities in the pentylenetetrazol (PTZ) seizure model.

Conclusions: Neuroactive steroids have comparable potencies in the 6‐Hz and PTZ models. Their structural specificity in both models corresponds with their activities as positive allosteric modulators of GABAA receptors, although ganaxolone is more potent than expected, probably because it has greater bioavailability. The 6‐Hz model may be a valuable tool in drug development for the identification of GABAergic AEDs.