bluuebunny/crossref_metadata_2025 huggingface dataset:
The medicolegal implications of hypoglycaemia in the newborn
Authors: Hawdon Jane M
Published: July 2007

Neonatal hypoglycaemia is commonly physiological, but failure of normal neonatal metabolic adaptation may occur, causing persistent and severe hypoglycaemia with concomitant brain injury. Little is known about the level and duration of neonatal hypoglycaemia which cause brain injury, and studies of the long-term effects of hypoglycaemia are flawed by confounding factors. This paper reviews the etiology, clinical significance and preventive management of neonatal hypoglycaemia, and makes recommendations for safe practice. Criteria for establishing an association between neonatal hypoglycaemia and brain injury are outlined.
Preference Fluency in Choice
Authors: Novemsky Nathan , Dhar Ravi , Schwarz Norbert , Simonson Itamar
Published: July 2007

The authors propose that consumer choices are often systematically influenced by preference fluency (i.e., the subjective feeling that forming a preference for a specific option is easy or difficult). Four studies manipulate the fluency of preference formation by presenting descriptions in an easy- or difficult-to-read font (Study 1) or by asking participants to think of few versus many reasons for their choice (Studies 2–4). As the authors predict, subjective experiences of difficulty increase choice deferral (Studies 1 and 2) and the selection of a compromise option (Studies 3 and 4), unless consumers are induced to attribute the experience to an unrelated cause. Unlike studies of decision conflict, these effects are obtained without changing the attributes of the alternatives, the composition of the choice sets, or the reference points. The authors discuss the theoretical and practical implications of the results.
The Shopping Momentum Effect
Authors: Dhar Ravi , Huber Joel , Khan Uzma
Published: July 2007

Shopping momentum occurs when an initial purchase provides a psychological impulse that enhances the purchase of a second, unrelated product. The authors propose that the most promising theoretical mechanism for shopping momentum comes from Gollwitzer's (1990) theory of implementation and deliberation mind-sets. Under this theory, shopping momentum occurs because the initial purchase moves the consumer from a deliberative to an implemental mind-set, thus driving subsequent purchases. After demonstrating the main shopping momentum effect, the authors support the mind-set theory by (1) demonstrating how an initial purchase induces implemental orientation and (2) by illustrating that an implementation mind-set leads to greater purchase. The authors then explore the boundaries of this effect by demonstrating how shopping momentum can be interrupted. Finally, they discuss alternative theoretical accounts for the results and explore consequences for marketing managers.
Interfirm Monitoring, Social Contracts, and Relationship Outcomes
Authors: Heide Jan B. , Wathne Kenneth H. , Rokkan Aksel I.
Published: July 2007

This article examines the effects of monitoring on interfirm relationships. Whereas some research suggests that monitoring can serve as a control mechanism that reduces exchange partner opportunism, there is also evidence showing that monitoring can actually promote such behavior. The authors propose that the actual effect of monitoring depends on (1) the form of monitoring used (output versus behavior) and (2) the context in which monitoring takes place. With regard to the form of monitoring, the results from a longitudinal field study of buyer–supplier relationships show that output monitoring decreases partner opportunism, as transaction cost and agency theory predict, whereas behavior monitoring, which is a more obtrusive form of control, increases partner opportunism. With regard to the context, the authors find that informal relationship elements in the form of microlevel social contracts serve as buffers that both enhance the effects of output monitoring and permit behavior monitoring to suppress opportunism in the first place.
Estimating Promotion Response When Competitive Promotions Are Unobservable
Authors: Moon Sangkil , Kamakura Wagner A. , Ledolter Johannes
Published: July 2007

This study addresses a problem commonly encountered by marketers who attempt to assess the impact of their sales promotions—namely, the lack of data on competitive marketing activity. In most industries, competing firms may have competitive sales data from syndicated services or trade organizations, but they seldom have access to data on competitive promotions at the customer level. Promotion response models in the literature either have ignored competitive promotions, focusing instead on the focal firm's promotions and sales response, or have considered the ideal situation in which the analyst has access to full information about each firm's sales and promotion activity. The authors propose a random coefficients hidden Markov promotion response model, which takes the competitor's unobserved promotion level as a latent variable driven by a Markov process to be estimated simultaneously with the promotion response model. This enables the authors to estimate cross-promotion effects by imputing the level of competitive promotions. The authors test the proposed model on synthetic data through a Monte Carlo experiment. Then, they apply and test the model to actual prescription and sampling data from two main competing pharmaceutical firms in the same therapeutic category. The two tests show that compared with several benchmark models, the proposed random coefficients hidden Markov model successfully imputes unobserved competitive promotions and, accordingly, reduces biases in the own- and cross-promotion parameters. Furthermore, the proposed model provides better predictive validity than the benchmark models.
Vertical distribution of spores of blade-forming Sarcothalia crispata (Gigartinaceae) and crustose corallines (Corallinaceae) in the water column
Authors: Opazo L. Felipe , Otaíza Ricardo D.
Published: July 2007

Changes in spore abundance of the blade-forming Sarcothalia crispata and crustose coralline seaweeds were determined to relate height above the substratum at which propagules are liberated with their dispersal potential. Recruit density was quantified on artificial substrata at the surface of the water column, mid-water, and seafloor. Spore abundance was determined in water samples obtained at the same levels during periods of calm and rough seas. Spore density was also determined along a transect running perpendicularly to the shore. Density of recruits S. crispata increased with depth, whereas coralline recruits were abundant at the seafloor level. During calm seas, spore density of S. crispata and crustose corallines increased with depth, but the latter were more variable. During rough seas, spore density was very high; spores of S. crispata increased toward the surface, or were homogenous in the water column, whereas distribution of crustose coralline spores was more variable. Finally, density of crustose coralline spores decreased more abruptly with distance from the shore than that of the bladed species. These results strongly suggest that the height at which spores are released (a correlate of algal morphology) influences spore distribution in the water column and the dispersal potential.
Nitrate reductase in the marine macroalga Kappaphycus alvarezii (Rhodophyta): oscillation due to the protein level
Authors: Granbom Malena , Lopes Patrícia F. , Pedersén Marianne , Colepicolo Pio
Published: July 2007

Nitrate reductase (NR; EC 1.6.6.1) of the marine red macroalga Kappaphycus alvarezii was examined in algae maintained under L:D and constant light conditions. Undenaturated protein had a molecular mass of about 210 kD (±23 kD); based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting techniques, the enzyme appears to be composed of two possibly identical subunits of 100 kD. The NR of K. alvarezii was recognized by 10 out of 17 monoclonal antibodies raised against the NR from the red alga Porphyra yezoensis. Basal parts of the algal thallus had higher NR protein content, although the highest activity of NR has been located previously in the apical thallus parts, suggesting a post-translational regulation. The cellular expression of NR exhibits a daily rhythm. In extracts of algae grown under either constant light or a light:dark cycle, staining with antibodies NR 6 and NR 10 showed that the amount of protein varied by a factor of about 2, with the maximum occurring in the early day phase.
Lesions of the Tegmentomammillary Circuit in the Head Direction System Disrupt the Head Direction Signal in the Anterior Thalamus
Authors: Bassett Joshua P. , Tullman Matthew L. , Taube Jeffrey S.
Published: July 2007

Head direction (HD) cells in the rodent limbic system are believed to correspond to a cognitive representation of directional heading in the environment. Lesions of vestibular hair cells disrupt the characteristic firing patterns of HD cells, and thus vestibular afference is a critical contributor to the HD signal. A subcortical pathway that may convey this information includes the dorsal tegmental nucleus of Gudden (DTN) and the lateral mammillary nucleus (LMN). To test the hypothesis that the DTN and LMN are critical components for generating HD cell activity, we made electrolytic lesions of the DTN or LMN in rats and screened for HD cell activity in the anterior thalamus. Directional activity was absent in all animals with complete LMN lesions and in animals with complete DTN lesions, although a few HD cells were isolated in animals with incomplete lesions. Some DTN-lesioned animals contained cells whose firing rates were modulated by angular head velocity. Although cells with bursting patterns of activity have been observed in the anterior dorsal nucleus of the thalamus of animals with disruption of vestibular inputs, this pattern of activity was not observed in either the LMN- or DTN-lesioned animals. The general absence of direction-specific activity in the anterior thalamus of animals with DTN or LMN lesions is consistent with the view that the DTN–LMN circuit is essential for the generation of HD cell activity.
Short-Term Depression at the Reciprocal Synapses between a Retinal Bipolar Cell Terminal and Amacrine Cells
Authors: Li Geng-Lin , Vigh Jozsef , von Gersdorff Henrique
Published: July 2007

Visual adaptation is thought to occur partly at retinal synapses that are subject to plastic changes. However, the locus and properties of this plasticity are not well known. Here, we studied short-term plasticity at the reciprocal synapse between bipolar cell terminals and amacrine cells in goldfish retinal slices. Depolarization of a single bipolar cell terminal for 100 ms triggers the release of glutamate onto amacrine cell processes, which in turn leads to GABAergic feedback from amacrine cells onto the same terminal. We find that this release of GABA undergoes paired-pulse depression (PPD) that recovers in <1 min (single exponential time constant, τ ≅ 12 s). This disynaptic PPD is independent of mGluR-mediated plasticity and depletion of glutamatergic synaptic vesicle pools, because exocytosis assayed via capacitance jumps (ΔCm) recovered completely after 10 s (τ ≅ 2 s). Fast application of GABA (10 mm) onto outside-out patches excised from bipolar cell terminals showed that the recovery of GABAAreceptors from desensitization depends on the duration of the application [fast recovery (<2 s) for short applications; slow (τ ≅ 12 s) for prolonged applications]. We thus blocked GABAAreceptors and retested the GABAergic response mediated by nondesensitizing GABACreceptors to two rapid glutamate puffs onto the bipolar cell terminal. These responses consistently displayed PPD. Furthermore, blocking AMPA-receptor desensitization with cyclothiazide, or evoking GABA release with NMDA receptors, did not reduce PPD. We thus suggest that depletion of synaptic vesicle pools in GABAergic amacrine cells is a major contributor to PPD.
Neural Circuits Mediate Electrosensory Behavior inCaenorhabditis elegans
Authors: Gabel Christopher V. , Gabel Harrison , Pavlichin Dmitri , Kao Albert , Clark Damon A. , Samuel Aravinthan D. T.
Published: July 2007

The nematodeCaenorhabditis elegansdeliberately crawls toward the negative pole in an electric field. By quantifying the movements of individual worms navigating electric fields, we show thatC. elegansprefers to crawl at specific angles to the direction of the electric field in persistent periods of forward movement and that the preferred angle is proportional to field strength.C. elegansreorients itself in response to time-varying electric fields by using sudden turns and reversals, standard reorientation maneuvers thatC. elegansuses during other modes of motile behavior. Mutation or laser ablation that disrupts the structure and function of amphid sensory neurons also disrupts electrosensory behavior. By imaging intracellular calcium dynamics among the amphid sensory neurons of immobilized worms, we show that specific amphid sensory neurons are sensitive to the direction and strength of electric fields. We extend our analysis to the motor level by showing that specific interneurons affect the utilization of sudden turns and reversals during electrosensory steering. Thus, electrosensory behavior may be used as a model system for understanding how sensory inputs are transformed into motor outputs by theC. elegansnervous system.
Psychophysical and Physiological Evidence for Parallel Afferent Pathways Mediating the Sensation of Itch
Authors: Johanek Lisa M. , Meyer Richard A. , Hartke Tim , Hobelmann Joseph Greg , Maine David N. , LaMotte Robert H. , Ringkamp Matthias
Published: July 2007

The neuronal pathways for itch have been characterized mainly based on responses to histamine. Intracutaneous application of histamine produces intense itch and a large area of axon-reflexive vasodilation (“flare”) around the application site. Both phenomena are thought to be mediated through neuronal activity in itch-specific, mechanoinsensitive C-fiber afferents (CMi). However, mechanical and electrical stimuli that do not activate CMi fibers can cause the sensation of itch, and itch may occur without flare, suggesting that other neuronal itch pathways exist. Because cutaneous application of spicules from the plantMucuna pruriens(cowhage) has been anecdotally reported to produce itch without flare, we performed psychophysical experiments to investigate whether the mechanisms underlying cowhage- and histamine-induced itch differ. Although histamine and cowhage produced itch of similar magnitude, the itch to cowhage was not correlated with the itch to histamine; some subjects had intense itch to cowhage and little itch to histamine and visa versa. Laser Doppler measurements of blood flow revealed that histamine led to a large area of vasodilation, whereas cowhage produced vasodilation restricted to the application site. Pretreatment of the skin with an antihistamine blocked the itch produced by histamine but did not prevent cowhage-induced itch. Desensitization of the skin with topical capsaicin abolished cowhage-induced itch but did not significantly alter histamine-induced itch. These findings indicate that cowhage itch is signaled through a population of capsaicin-sensitive afferent nerve fibers that is distinct from CMi fibers mediating histamine-induced itch. Cowhage may be useful to investigate the neural pathway mediating nonhistaminergic itch.
Nonthermal Activation of Transient Receptor Potential Vanilloid-1 Channels in Abdominal Viscera Tonically Inhibits Autonomic Cold-Defense Effectors
Authors: Steiner Alexandre A. , Turek Victoria F. , Almeida Maria C. , Burmeister Jeffrey J. , Oliveira Daniela L. , Roberts Jennifer L. , Bannon Anthony W. , Norman Mark H. , Louis Jean-Claude , Treanor James J. S. , Gavva Narender R. , Romanovsky Andrej A.
Published: July 2007

An involvement of the transient receptor potential vanilloid (TRPV) 1 channel in the regulation of body temperature (Tb) has not been established decisively. To provide decisive evidence for such an involvement and determine its mechanisms were the aims of the present study. We synthesized a new TRPV1 antagonist, AMG0347 [(E)-N-(7-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl)-3-(2-(piperidin-1-yl)-6-(trifluoromethyl)pyridin-3-yl)acrylamide], and characterized itin vitro. We then found that this drug is the most potent TRPV1 antagonist known to increase Tbof rats and mice and showed (by using knock-out mice) that the entire hyperthermic effect of AMG0347 is TRPV1 dependent. AMG0347-induced hyperthermia was brought about by one or both of the two major autonomic cold-defense effector mechanisms (tail-skin vasoconstriction and/or thermogenesis), but it did not involve warmth-seeking behavior. The magnitude of the hyperthermic response depended on neither Tbnor tail-skin temperature at the time of AMG0347 administration, thus indicating that AMG0347-induced hyperthermia results from blockade of tonic TRPV1 activation by nonthermal factors. AMG0347 was no more effective in causing hyperthermia when administered into the brain (intracerebroventricularly) or spinal cord (intrathecally) than when given systemically (intravenously), which indicates a peripheral site of action. We then established that localized intra-abdominal desensitization of TRPV1 channels with intraperitoneal resiniferatoxin blocks the Tbresponse to systemic AMG0347; the extent of desensitization was determined by using a comprehensive battery of functional tests. We conclude that tonic activation of TRPV1 channels in the abdominal viscera by yet unidentified nonthermal factors inhibits skin vasoconstriction and thermogenesis, thus having a suppressive effect on Tb.
Contribution of the Putative Inner-Pore Region to the Gating of the Transient Receptor Potential Vanilloid Subtype 1 Channel (TRPV1)
Authors: Susankova Klara , Ettrich Rudiger , Vyklicky Ladislav , Teisinger Jan , Vlachova Viktorie
Published: July 2007

The transient receptor potential vanilloid receptor-1 (TRPV1) is a sensory neuron-specific nonselective cation channel that is gated in response to various noxious stimuli: pungent vanilloids, low pH, noxious heat, and depolarizing voltages. By its analogy to K+channels, the S6 inner helix domain of TRPV1 (Y666-G683) is a prime candidate to form the most constricted region of the permeation pathway and might therefore encompass an as-yet-unmapped gate of the channel. Using alanine-scanning mutagenesis, we identified 16 of 17 residues, that when mutated affected the functionality of the TRPV1 channel with respect to at least one stimulus modality. T670A was the only substitution producing the wild-type channel phenotype, whereas Y666A and N676A were nonfunctional but present at the plasma membrane. The periodicity of the functional effects of mutations within the TRPV1 inner pore region is consistent with an α-helical structure in which T670 and A680 might play the roles of two bending “hinges.”
Direct Instrumental Conditioning of Neural Activity Using Functional Magnetic Resonance Imaging-Derived Reward Feedback
Authors: Bray Signe , Shimojo Shinsuke , O'Doherty John P.
Published: July 2007

Successful learning is often contingent on feedback. In instrumental conditioning, an animal or human learns to perform specific responses to obtain reward. Instrumental conditioning is often used by behavioral psychologists to train an animal (or human) to produce a desired behavior. Shaping involves reinforcing those behaviors, which in a stepwise manner are successively closer to the desired behavior until the desired behavior is reached. Here, we aimed to extend this traditional approach to directly shape neural activity instead of overt behavior. To achieve this, we scanned 22 human subjects with functional magnetic resonance imaging and performed image processing in parallel with acquisition. We delineated regions of interest (ROIs) in finger and toe motor/somatosensory regions and used an instrumental shaping procedure to induce a regionally specific increase in activity by providing an explicit monetary reward to reinforce neural activity in the target areas. After training, we found a significant and regionally specific increase in activity in the ROI being rewarded (finger or toe) and a decrease in activity in the nonrewarded region. This demonstrates that instrumental conditioning procedures can be used to directly shape neural activity, even without the production of an overt behavioral response. This procedure offers an important alternative to traditional biofeedback-based approaches and may be useful in the development of future therapies for stroke and other brain disorders.
Chronic Mild Stress during Gestation Worsens Neonatal Brain Lesions in Mice
Authors: Rangon Claire-Marie , Fortes Silvia , Lelièvre Vincent , Leroux Philippe , Plaisant Frank , Joubert Chantal , Lanfumey Laurence , Cohen-Salmon Charles , Gressens Pierre
Published: July 2007

Cerebral palsy remains a public health priority. Recognition of factors of susceptibility to perinatal brain lesions is key for the prevention of cerebral palsy. In most cases, the pathophysiology of these lesions is thought to involve prior exposure to predisposing factors that make the developing brain more vulnerable to perinatal events. The present study tested the hypothesis that exposure to chronic minimal stress throughout gestation would sensitize the offspring to neonatal excitotoxic brain lesions, which mimic lesions observed in cerebral palsy. Pregnant mice were exposed to chronic, ultramild stress, applied throughout gestation. Neonatal brain lesions were induced by intracerebral injection of glutamate analogs. Excitotoxic lesions were significantly worsened in pups exposed to gestational stress. Stress induced a significant rise of circulating corticosterone levels both in pregnant mothers and in newborn pups. The deleterious effects of stress on excitotoxicity were totally suppressed in mice with reduced levels of glucocorticoid receptors. Stress induced a significant increase of neopallial NMDA binding sites in the offspring. At adulthood, animals exposed to stress and neonatal excitotoxic challenge showed a significant impairment in the Morris water maze test when compared with animals exposed to the excitotoxic challenge but not the gestational stress. These findings suggest that stress during gestation, which may mimic low-level stress in human pregnancy, could be a novel risk factor for cerebral palsy.
Role of the Primate Amygdala in Fear-Potentiated Startle: Effects of Chronic Lesions in the Rhesus Monkey
Authors: Antoniadis Elena A. , Winslow James T. , Davis Michael , Amaral David G.
Published: July 2007

In experiment 1, we assessed the role of the primate amygdala and hippocampus in the acquisition of learned fear measured with fear-potentiated startle. Three groups of six rhesus monkeys were prepared with bilateral ibotenic acid lesions of the amygdaloid complex and the hippocampus or were sham operated. Selective ibotenic acid lesions of the amygdala, but not the hippocampus, blocked the acquisition of fear-potentiated startle. In experiment 2, we assessed the role of the primate amygdala in the expression of fear-potentiated startle. Surprisingly, animals that sustained amygdala damage after they successfully learned fear-potentiated startle expressed normal fear-potentiated startle, despite a complete amygdala lesion based on magnetic resonance imaging assessments. These results suggest that although the amygdala is necessary for the initial acquisition of fear-potentiated startle, it is not necessary for the retention and expression of fear-potentiated startle. These findings are discussed in relation to the role of the amygdala in emotional learning and in cross-species comparisons of emotional behavior.
Household Composition and Poverty among Female‐Headed Households with Children: Differences by Race and Residence*
Authors: Snyder Anastasia R. , McLaughlin Diane K. , Findeis Jill
Published: July 2007

Abstract We examine race and residential variation in the prevalence of female‐headed households with children and how household composition is associated with several key economic well‐being outcomes using data from the 2000 5% Public Use Microdata Sample of the U.S. Census. Special attention is paid to cohabiting female‐headed households with children and those that are headed by a single grandmother caring for at least one grandchild, because these are becoming more common living arrangements among female‐headed households with children. We find that in 2000: (1) cohabiting and grandmother female‐headed households with children comprised over one‐fourth of all female‐headed households with children, (2) household poverty is highest for female‐headed households with children that do not have other adult household earners, (3) earned income from other household members lifts many cohabiting and grandparental female‐headed households out of poverty, as does retirement and Social Security income for grandmother headed households, and (4) poverty is highest among racial/ethnic minorities and for female‐headed households with children in nonmetro compared to central cities and suburban areas.
Allusion
Authors: Machacek Gregory
Published: July 2007

The study of allusion has been beset by limiting assumptions, conceptual murkiness, and terminological imprecision; moreover, many poststructuralist theorists regard such study as having been superseded by newer conceptions of intertextuality. This essay seeks to clarify the nature of allusion and the terminology by which it is analyzed and to place it on a firmer footing within poststructuralist literary criticism. I distinguish two forms of allusion often conflated-learned reference and phraseological adaptation–and elucidate the elements of a phraseological adaptation. I distinguish diachronic allusion from synchronic intertextuality, as poststructuralist theorists insist should be done, but then suggest how coordinating the two can enrich the analytic power of each way of conceiving textual interrelation.
Comparative User-Focused Evaluation of User Guides: A Case Study
Authors: Ganier Franck
Published: July 2007

A comparative evaluation of two user guides—the document traditionally used by a company and a model document designed on the basis of research results and recommendations—was carried out using a number of complementary approaches focusing on the user. The quality and suitability of these documents for the target audience were assessed in terms of content, structure, presence of certain organizational devices (such as headings) and pictures included. The results revealed that the model document was more attractive, more efficient, and better adapted to users' needs, thanks to its modular organization (being structured according to “functions”), a large number of pictures, the presence of headings, and rationalization of the vocabulary used.
Training Teachers and Serving Students: Applying Usability Testing in Writing Programs
Authors: McGovern Heather
Published: July 2007

Teachers often test course materials by using them in class. Usability testing provides an alternative: teachers receive student feedback and revise materials before teaching a class. Case studies based on interviews and observations with two teaching assistants who usability tested materials before teaching introductory technical writing demonstrate how usability testing can make novice teachers more confident about and help them predict student experiences with their assignments. By helping to train teachers, usability testing can also help better serve students.
Effect of Premature Menopause on Sexuality
Authors: Graziottin Alessandra
Published: July 2007

Premature menopause, that is, menopause – spontaneous or iatrogenic – occurring at or before the age of 40 years, affects sexual identity, sexual function and sexual relationships. The woman's health, wellbeing and achievement of life's goals may be variably impaired. Factors modulating the individual's sexual outcome after premature menopause include: etiological heterogeneity of premature menopause and associated medical and sexual comorbidities; psychosexual vulnerability to premature menopause and associated infertility in survivors of childhood and adolescent cancers; impact of premature menopause on women's sexual identity, sexual function – particularly the biological basis of desire, arousal, orgasm and vaginal receptivity – and sexual relationships; partner-related factors; fertility issues; and preventive/therapeutic measures. Hormone therapy is indicated but long-term safety data are lacking. An interdisciplinary medical and psychosexual approach comprises appropriate counseling, fertility protection, when feasible, individualized hormone therapy and specific psychosexual treatment(s). Further research on fertility protection and the safety of long-term hormone therapy after premature menopause is needed.
Treeline advance - driving processes and adverse factors
Authors: Holtmeier Friedrich Karl , Broll Gabriele E.
Published: July 2007

The general trend of climatically-driven treeline advance is modified by regional, local and temporal variations. Treelines will not advance in a closed front parallel to the shift of any isotherm to higher elevations and more northern latitudes. The effects of varying topography on site conditions and the after-effects of historical disturbances by natural and anthropogenic factors may override the effects of slightly higher average temperatures. Moreover, the varying treeline-forming species respond in different ways to a changing climate. Forest advance upwards and northwards primarily depends on successful regeneration and survival of young growth rather than on increasing growth rates of mature trees. Every assessment of treeline response to future climate change must consider the effects of local site conditions and feedbacks of increasing tree population in modulating the climatically-driven change. Treeline-shift will influence regional and local climates, pedogenesis, plant communities, animal populations and biodiversity as well as having a considerable effect on economic changes in primary production. A better understanding of the functional relationships between the many treeline-relevant factors and treeline dynamics can be achieved only by extensive research at different scales within different climatic regions supported by as many as possible experimental studies in the field together with laboratory and remote sensing techniques.
The impact of process stress on suspended anchorage‐dependent mammalian cells as an indicator of likely challenges for regenerative medicines
Authors: Zoro B.J.H. , Owen S. , Drake R.A.L. , Hoare M.
Published: July 2007

To quantify the engineering shear constraint on processing, the effect of capillary shear stress (pipe flow) on suspended anchorage‐dependent mammalian cells has been investigated. Exposure of cultured rat aortic smooth muscle cells to repeated capillary shear stress (2–120 N m−2) causes a decrease in total number of cells, number of intact cells and number of cells able to grow. The optimum wall shear stress for cell survival was found to be 10–50 N m−2 (flowrate 4–20 mL/min, I.D. 0.45 mm). Cell populations which are able to grow after exposure to shear stress do not exhibit reduced growth rate or altered metabolism. Biotechnol. Bioeng. 2008;99: 468–474. © 2007 Wiley Periodicals, Inc.
Ground state energy scaling laws during the onset and destruction of the intermediate state in a type I superconductor
Authors: Choksi Rustum , Conti Sergio , Kohn Robert V. , Otto Felix
Published: July 2007

The intermediate state of a type I superconductor is a classical example of energy‐driven pattern formation, first studied by Landau in 1937. Three of us recently derived five different rigorous upper bounds for the ground‐state energy, corresponding to different microstructural patterns, but only one of them was complemented by a lower bound with the same scaling [Choksi, Kohn, and Otto, J. Nonlinear Sci. 14 (2004), 119–171]. This paper completes the picture by providing matching lower bounds for the remaining four regimes, thereby proving that exactly those five different regimes are traversed with an increasing magnetic field. © 2007 Wiley Periodicals, Inc.
A Note on Second Harmonics Generated by a Surface Wave on a Warm Plasma Half‐Space
Authors: Ghosh B. , Das K. P.
Published: July 2007

A part of the second harmonics generated through the self‐interaction of a surface wave on a warm plasma half‐space is shown not to have a surface wave character but represents a wave propagating obliquely away from the plasma‐vacuum interface into the bulk of the plasma.
On the Thermodynamics of Dense Plasmas
Authors: Kraeft W. D. , Rother T.
Published: July 2007

Thermodynamic functions of dense plasmas are determined in terms of the single particle self energy. The latter is expressed in terms of T‐matrices of the scattering theory. Explicit evaluations are carried out for the highly degenerate two component plasma.
Increased Power Concentration and its Effect on the Discharge Parameters of the Low Pressure Hg‐rare Gas Positive Column I. Variation of Current
Authors: Kreher J. , Stern W.
Published: July 2007

By measuring the radiant flux of the resonance lines of mercury, the field strength and the electron energy distribution function the influence of the current on the parameters, especially on the energy balance of the Hg—Ar positive column is investigated, compared with a kinetic model, and interpreted. The decrease in yield of the 254 nm radiation with increasing current is linked to a corresponding increase of the losses due to elastic collisions with the rare gas atoms and is caused by the changes in the electron energy distribution function. Moreover, the influence of gas temperature, Hg‐densities and effective life times is investigated.
Plasma Properties and Neutral Gas Densities in Hg‐Rare Gas Discharges
Authors: Kreher J. , Stern W.
Published: July 2007

The density of the neutral gases in Hg‐rare gas discharges and their spatial distribution is controlled by the discharge parameters as well as by the externally adjustable partial pressures. Essential quantities in this context are the gas temperature produced by elastic collisions, the ion transport by the discharge current, the processes governing the wall temperature, and ambipolar diffusion. Despite equal partial pressures different densities may occur, which, in turn, will influence the parameters of the discharge. This has effects on the assessment of the methods of Hgvapour pressure adjustment and on the evaluation of the measured values. These effects are demonstrated, especially by field strength measurements, for a wide parameter range.
Ignition Processes in ac Plasma Displays
Authors: Röpcke J. , Zahn R.‐J.
Published: July 2007

The ignition behaviour of discharge cells in ac plasma displays, their ignition statistics and interaction processes occurring between several ignited cells are described and interpreted with a view to basic problems of gas discharge and solid state physics. Ac plasma displays of three different sizes were investigated: PAF 58, 90 and PAF 128.
2 D Tokamak Edge Simulation Including Impurities
Authors: Krech M. , Neuhauser J. , Schneider W.
Published: July 2007

In the first part of this paper we present multifluid model calculations of marfe instabilities in a simple geometry. Assuming carbon as the dominant impurity, the time evolution of the 2D Marfe is followed and typical e‐folding times and their variation with the poloidal and radial heat conductivities are determined. In part two of this paper we present a scrape‐off layer simulation in a typical x‐point geometry using a simplyfied hydrogen recycling model and again carbon as impurities. Other impurity species can be treated as well.
ASDEX Edge and Divertor Simulation and the Problem of Incomplete and Inaccurate Experimental Data
Authors: Schneider W. , Neuhauser J. , Haas G. , McCormick K. , Tsois N. , Wunderlich R.
Published: July 2007

The one‐dimensional hydrodynamic code SOLID coupled with the two‐dimensional Monte Carlo neutral gas code DEGAS are used to simulate the scrape‐off layer and divertor recycling region of the ASDEX tokamak. A numerical data base is created for the relevant parameter regime and compared to the limited amount of experimental data. A reasonable fit with ohmic data is obtained, assuming classical heat flow along field lines and allowing for varying divertor saturation. The problem of experimental errors on one side and deficiencies in the theoretical model on the other side are discussed.
Modelling of the 2‐Dimensional Structure and Impurity Transport for a Scrape‐Off Layer with a Solid Limiter
Authors: Kawamura T. , Ono T. , Masuda Y. , Reiter D.
Published: July 2007

First the 2‐dimensional modelling of a scrape‐off layer with a solid limiter is performed. After the plasma in a scrape‐off layer is calculated by a plasma code SLIM based on the 2‐dimensional fluid equations with source terms due to neutral particles, the neutral transport is calculated by a Monte Carlo code EIRENE with the use of the results by SLIM and these two calculations are iteratively performed until a nearly self‐consistent result is obtained. Next, in the scrape‐off plasma thus obtained, ionization of neutral impurity particles ejected from the first wall and random diffusion of the charged impurities across the magnetic field lines are simulated by a Monte Carlo method. From the statistical analysis on the numerical results the screening efficiency of a scrape‐off layer, impurity redeposition rate and behaviour of impurities in a scrape‐off layer are analyzed.
Temperature Determination from the Continuous Emission of a Dense Argon Plasma
Authors: Szymanski Z.
Published: July 2007

The temperature of the laser sustained plasma has been determined from the continuum emission coefficient at different wavelengths. The experiments were performed in an argon plasma at the pressure of 10 atm. The spurious continuum resulting from merging of spectral lines was investigated numerically. Its influence on the measured emission coefficient in the red region has been found to be considerable.
Weak Ion Acoustic Double Layers in a Warm Plasma
Authors: Sutradhar Das S. , Bujarbarua S.
Published: July 2007

The analytic solutions of the weak ion acoustic double layers in warm unmagnetized and magnetized plasma have been presented with the fluid equation for ions and an arbitrary equation of state for the hot electrons. It has been shown that double layers solutions exist for both magnetized and unmagnetized plasmas when two Boltzmann model for electrons are considered. The potential, the thickness and the velocity of such type of double layers have been calculated and compared with those for the cold plasma.
Exchange‐Correlation Potentials for Hydrogen at any Degeneracy
Authors: Stolzmann W. , Kraeft W. D. , Fromhold‐Treu I.
Published: July 2007

Numerical values of the exchange‐correlation contributions of the pressure, the free energy and the chemical potential are obtained for hydrogen at any degree of degeneracy. The evaluations are performed with the RPA‐dielectric function for the Montroll‐Ward contribution by integration over real frequencies. The influence of the proton degeneracy is analyzed for increasing degeneracy of the electrons. A comparison with the correlation part of the free energy and of the chemical potential without proton degeneracy is given.
Effects of Non‐Ideality and Non‐Equilibrium in the Cathode Spot Plasma of Vacuum Arcs
Authors: Anders S. , Anders A.
Published: July 2007

The cathode spot plasma of a metal vapour arc in vacuum is non‐ideal (electron density ne ∼ 1025–1027 m−3, temperature T ∼ 1–5 eV, plasma parameter Γ = 0.6−0.1). The fast expansion of the spot plasma into the ambient vacuum leads to a non‐equilibrium charge state distribution (“frozen” state of ionization). The calculations presented show that the freezing of the different charge states appears at different distances from the spot, therefore at different plasma densities and temperatures. In this way, specific proportions of the ion species are produced which do not agree with any equilibrium state. The freezing of the charge states occurs near the cathode spot (γ = 5–50 μm, γ — distance from the spot centre) where the plasma is weakly non‐ideal (Γ = 0.2–0.6).
Kinetic Current‐Convective Instability in Hot Electron Plasma
Authors: Khalil Sh. M. , Sayed Y. A. , Zaki N. G.
Published: July 2007

The kinetic current‐convective instability excited in a hot electron plasma, i.e. for Te ≫ Ti, is investigated in the linear stage. Density and temperature of plasma components have gradients along the x‐direction.

In the absence of longitudinal current (u = 0) and homogeneous temperature the instability is also excited with maximum growth rate much exceeding that obtained in the case of u ≠ 0. Gradual increasing of the ion temperature over that of the electrons and a large density gradient leads to reduce the instability in the linear stage.
80 Ev Imaging of Laser Produced Plasmas for Different Z Materials at 1.06, 0.53 and 0.26 μM
Authors: Benattar R. , Godart J. L.
Published: July 2007

The VUV emissions (155 Å) of laser produced plasma on massive plane targets with different Z numbers are recorded according three laser wavelengths with a pinhole camera associated with a multilayered mirror.

The 2D dimensions of these VUV images are compared with the sizes of the focal spots through the 1 Kev pinhole image sizes recorded at the same laser intensity (51014 W/cm2, 600 ps). The lateral and axial dimensions of the VUV emissions of Al, Cu, Au plasmas are analyzed and give informations on the radiations‐hydrodynamic behavior of Laser heated plane targets with respect to the wavelength of the incident laser.
Conductivity and Cross Sections for Partially Ionized Cesium and Sodium Plasmas
Authors: Arndt S. , Sigeneger F. , Bialas F. , Kraeft W.‐D. , Luft M. , Meyer T. , Redmer R. , Röpke G. , Schlanges M.
Published: July 2007

The electroconductivity of partially ionized cesium and sodium plasmas is calculated within the frame of the Chapman‐Enskog method. The composition of the plasma and the transport cross section for electron‐electron and electron‐ion scattering were evaluated in previous papers (Redmer et al. [1], Sigeneger et al. [2]). This paper is mainly devoted to the influence of neutrals on the electroconductivity. Therefore, the total and transport cross section for electron‐atom scattering are determined numerically. The results for the cross sections and the conductivity are compared with experiments and other theoretical approaches.
Mutual Focusing of Electromagnetic Waves in the Ionospheric Plasma
Authors: Laxmi V. N. , Srivastava M. P.
Published: July 2007

A one dimensional analysis has been carried out to study the interaction of two co‐axial electromagnetic waves propagating vertically at close frequencies in the F‐region ionosphere. Coupled equations for the beam width parameters of the two interacting waves have been set up to determine the intensities in the axial direction. Two cases have been examined, i one of the em beams is assumed to be weak so that its influence on the medium as well as on the other beam is neglected, ii) the two beams are of comparable intensities so that they mutually influence each other. In the first case the axial intensity of the weak beam grows at the expense of the other one which is strong. Whereas in the other situation mutual influence results in the focusing of both the beams.
Initiation of Gas Discharges in Plasma Displays Assisted by Electron Emission of Thin Insulators
Authors: Röpcke J. , Zimdahl T. , Schlott D. , Glaefeke H.
Published: July 2007

At present many efforts are done for the development of colour plasma displays (PD). One main problem is to secure a reliable ignition, provided by a suitable concentration of starting particles in the discharge cells (priming). In this paper a new priming method is proposed using the exoelectron emission (EEE) of thin insulators. The influence of the EEE on the ignition behaviour of ac PD cells is investigated and compared with direct measurements of the afteremission of MgO, Al2O3 and MgAl2O4. Auger electron spectroscopy (AES), residual gas mass spectra and Ar+ etching are additionally used methods.
Pulsed Operation of High‐Pressure‐Sodium Discharge Lamps
Authors: Günther K. , Kloss H.‐G. , Lehmann T. , Radtke R. , Serick F.
Published: July 2007

Results of spectral and photometric measurements are presented for pulsed operated high‐pressure‐sodium lamps. Choosing for the colour temperature a value of 3000 K, the output spectrum was optimized with respect to colour rendition and lamp efficacy taking the pulse parameters, the sodium mole fraction, and the cold spot temperature as quantities to be varied. For the nominal rating of 70 W a maximum lamp efficacy of 70 lm/W and a colour rendering index of 40 can be obtained. Further improvements of the colour rendition require an enhanced sodium vapour pressure which can be achieved by operating the lamp at rised cold spot temperature.
Stark Broadening Regularities within Successive Ionization Stages in Krypton and Xenon
Authors: Purić J. , Djeniže S. , Labat J. , Srećković A. , Platiša M.
Published: July 2007

On the basis of existing experimental and theoretical results on Stark widths of neutral and multiply ionized states of krypton and xenon, we have indicated existence of certain regularities of Stark broadening for ns‐np types of transitions. These regularities were used to estimate the Stark widths of spectral lines from KrIV and XeI spectra that have not yet been measured or calculated.
Low Temperature Dry Etching of Graphite Anodes in Hydrogen Glow Discharges
Authors: Nawra J. , Pfau S. , Resztak A. , Richter Th. , Rutscher A.
Published: July 2007

To discribe the temperature dependence of the etching rate of graphite in a hydrogen glow discharge a model is discussed taking into accout the transition from CH4 to CH as the main etching product with increasing temperature.
On the Relaxation of Energetic Electrons in Plasmas
Authors: Braglia M. , Winkler R. , Wilhelm J.
Published: July 2007

The impact of individual collision processes on the relaxation of the velocity distribution function of a group of electrons, initially localized in a narrow region at relatively high energies, has been studied. By having recourse to solutions of the non‐stationary Boltzmann equation and to corresponding Monte‐Carlo simulations, the temporal behaviour of electrons in CO2 plasmas, both in the absence and the presence of an external dc field, has been investigated. A microphysical interpretation of observed relaxation phenomena, based on the data relevant to the individual collision processes, is also given.
Collisional — Radiative Model of Helium Plasma. I. Description of the Model
Authors: Slavík J.
Published: July 2007

We present a collisional‐radiative model of helium plasma with explicit inclusion of metastable state influences and give results of numerical calculations of population coefficients and effective reaction rates (generalization of effective ionization and recombination coefficients for the case when metastable states are not explicitly included) for a large region of electron densities and temperatures for optically thin and thick helium plasma. The model is described in this paper.
Collisional — Radiative Model of Helium Plasma. II. Global Population Coefficients
Authors: Slavík J.
Published: July 2007

We present results of our calculation of global population coefficients based on a collisional — radiative model of the helium plasma. The results are given for 23P, 21P, 33S, 31S, 33P, 31D, 33D, 31P, 43 and 41 states of helium atoms. We consider electron densities from 107 to 1018 cm−3 and electron temperature from 1 to 10 eV. The electron distribution function is considered to be Maxwellian and the plasma to be radiatively thin.