bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical Model of the Rapidly Activating Delayed Rectifier Potassium Current IKr in Rabbit Sinoatrial Node
Authors: OEHMEN CHRISTOPHER S. , GILES WAYNE R. , DEMIR SEMAHAT S.
Published: August 2003

Role of IKr in Rabbit Sinoatrial Node.
Introduction: A rapidly activating delayed rectifier potassium current (IKr) is known to have an important role in determining the properties of spontaneous pacing in enzymatically isolated rabbit sinoatrial node (SAN) cells. The functional characteristics of IKr are conferred by its dependence on time, voltage, and external potassium. The aim of this study was to develop a rigorous mathematical representation for IKr based on experimental findings and to investigate the role of IKr in the automaticity and intercellular communication of SAN cells.

Methods and Results: A Markov model was developed using available experimental data for IKr in rabbit SAN. The dependence of IKr on external potassium, [K+]o, was incorporated using data from both in vitro preparations and results from heterologous expression experiments for this ether‐a‐go‐go related gene product. Our simulation results show the following. (1) IKr is the dominant repolarizing current in rabbit SAN cells. (2) Deactivation of IKr contributes to the net current change during the early diastolic depolarization phase. (3) Inward rectification of IKr results in a decrease in membrane resistance during repolarization relative to plateau. (4) The complex [K+]o dependence of IKr confers [K+]o insensitivity on isolated cells, which may account for the sensitivity of pacing rate to elevated [K+]o at the tissue level.

Conclusion: Model results show that IKr mediates diastolic depolarization by the kinetics of its decay and by lowering resistance during late repolarization. In elevated [K+]o, increased chord conductance is balanced by the changes in kinetics and voltage dependence of IKr so that the pacing rate of single cells may be more [K+]o insensitive than expected. In addition, elevated [K+]o increases IKr magnitude during repolarization but lowers resistance, so current flow through gap junctions is less able to hyperpolarize pacing cells.
Cryothermic Ablation Within the Coronary Sinus of an Epicardial Posterolateral Pathway
Authors: GAITA FIORENZO , PAPERINI LUCA , RICCARDI RICCARDO , FERRARO ANNA
Published: August 2003

Cryoablation Within the Coronary Sinus. Radiofrequency ablation inside the coronary sinus (CS) is associated with the risk of vein stenosis, or perforation or damage to the circumflex artery. Cryothermic ablation has proved less harmful, but there are no data on its use within a venous structure. A patient with a posterolateral accessory pathway underwent several unsuccessful attempts at endocardial ablation. Ablation then was performed with cool energy within the CS, where the shortest VA interval and a possible Kent potential were recorded. Selective left coronary angiography showed a normal circumflex artery and the absence of lesions of the CS. Six months later, the patient was asymptomatic without taking antiarrhythmic drugs. We conclude that cryoablation within the CS may be effective and safe.
Linearly Scaled, Rate‐Invariant Normal Limits for QT Interval: Eight Decades of Incorrect Application of Power Functions
Authors: RAUTAHARJU PENTTI M. , ZHANG ZHU‐MING
Published: August 2003

Rate‐Invariant Normal Limits for QT Interval.
Introduction: Normal limits for QT traditionally are derived as mean ± 2*SD, with rate adjustment done by dividing QT values by power functions such as RR1/2 (proportional scaling).

Methods and Results: We evaluated procedures for deriving normal limits by comparing adjusted QT distributions versus heart rate using ECG data of 11,739 normal men and women aged ≥ 40 years. QT decreased as predicted by many power functions with heart rate but its SD remained relatively unchanged. Consequently, proportional scaling induced rate‐dependent distortion of normal limits. Furthermore, QT distributions by heart rate were variably skewed and non‐normal. Therefore, normal limits expressed as mean ± 2*SD were misleading. Omission of regression intercept was an additional reason for failure of Bazett's and Fridericia's formulas. Regularized normal limits for adjusted QT (Qta) were obtained with linear instead of proportional scaling of type QTa = QT + k1*(1 – RRk2), for instance, with k2 = 0.5, k1 = 0.360 for males and 0.353 for females, or with k2 = 0.42, k1 = 0.414 for males and 0.420 for females. With linear scaling, QTa = 460 msec was established as the upper 2% normal limit, with 32 msec as the limit for a significant QTa increase from reference ECG in serial comparison.

Conclusion: Traditional procedures for establishment of normal limits failed because of proportional scaling, assumption of normal QT distribution, or omission of regression intercept. Percentile distributions of linearly scaled adjusted QT produced regularized rate invariant normal limits within normal sinus rates.
Bundle Branch Reentrant Tachycardia in Patients with Apparent Normal His‐Purkinje Conduction: The Role of Functional Conduction Impairment
Authors: LI YI‐GANG , GRÖNEFELD GERIAN , ISRAEL CARSTEN , BOGUN FRANK , HOHNLOSER STEFAN H.
Published: August 2003

Bundle Branch Reentry Due to Functional His‐Purkinje Block.
Introduction: His‐Purkinje conduction delay, manifested by bundle branch block QRS complex configuration or by HV interval prolongation, is considered an essential condition for maintenance of bundle branch reentrant tachycardia (BBRT).

Methods and Results: Of 178 patients with different types of ventricular tachycardia (VT), 13 were found to have BBRT as the underlying electrophysiologic mechanism. Of these 13 patients (9 men and 4 women; mean age 64 ± 13 years), 6 had an HV interval ≤55 msec (group A), and 7 had a prolonged HV interval (>55 msec; group B) during sinus rhythm (SR). PR interval (169 ± 32 vs 339 ± 138 msec, P = 0.01) and QRS duration (116 ± 17 vs 167 ± 29 msec, P = 0.003) during SR were significantly shorter in group A than in group B. In group A, the HV interval was significantly longer during VT than during SR (73 ± 18 vs 47 ± 7 msec, P = 0.007). There were more patients with functional His‐Purkinje block (split His potentials, a jump of HV interval induced by programmed atrial stimulation or burst pacing) or phase 3 block in group A than group B (6/6 patients vs 0/7 patients, P < 0.001). Successful ablation of the right bundle branch was performed in all 13 patients without deteriorating AV block. Two patients died in each group, and VTs (other than BBRT) or ventricular fibrillation were documented by ICD electrogram storages in 4 patients during follow‐up of 27 ± 17 months.

Conclusion: A prolonged HV interval during SR is not a prerequisite for BBRT. Functional His‐Purkinje system abnormalities appear to be the electrophysiologic substrate for this specific type of BBRT.
Global P Wave Duration on the 65‐Lead ECG: Single‐Site and Dual‐Site Pacing in the Structurally Normal Human Atrium
Authors: GOZOLITS STEFAN , FISCHER GERALD , BERGER THOMAS , HANSER FRITZ , ABOU‐HARB MARIA , TILG BERNHARD , PACHINGER OTMAR , HINTRINGER FLORIAN , ROITHINGER FRANZ X.
Published: August 2003

Global P Wave Duration on the 65‐Lead ECG.
Introduction: Pacing is believed to prevent atrial fibrillation by reducing atrial activation time. Exact correlation between P wave duration (PWD) on surface ECG and endocardial atrial activation time is still unexplored.

Methods and Results: In 15 patients without structural heart disease (9 women, age 45 ± 14 years), single site [high right atrium (HRA), coronary sinus ostium (CSos), distal CS (CSd), high RA septum (Bachmann's bundle, BB)] and dual‐site pacing (various combinations) was performed after ablation of supraventricular tachycardia. A 65‐lead surface ECG was recorded simultaneously. Endocardial atrial activation time was measured off‐line (stimulus – last bipolar recording), and the respective PWD was assessed using the root mean square and 65‐channel summary plots. PWD during pacing from BB was significantly shorter (96 ± 12 msec) than during HRA (121 ± 15 msec), CSos (108 ± 9 msec), and CSd pacing (126 ± 14 msec; P < 0,01, respectively). PWD during dual‐site pacing (HRA + BB, 91 ± 14 msec; HRA + CSos, 96 ± 7 msec; HRA + CSd, 90 ± 7 msec; BB + CSd, 96 ± 12 msec) was not significantly shorter than during pacing from BB. Correlation between endocardial atrial activation time and PWD was 0.83.

Conclusion: PWD during single‐site and dual‐site atrial pacing represents endocardial atrial activation time and can be measured precisely using the 65‐lead surface ECG. The fact that high septal pacing results in the shortest PWD may have implications for preventive pacing in patients with atrial fibrillation.
The effect of surfactant monolayers on vortex rings formed from an impacting water drop
Authors: Saylor J. R. , Grizzard N. K.
Published: September 2003

The impact of a falling drop with a flat liquid surface can result in the formation of a subsurface vortex ring that penetrates a significant distance into the liquid bulk. Herein an experimental study of these vortex rings is presented for water drops striking a water surface. The effect of surfactant monolayers was investigated by measuring the vortex velocity for water surfaces that were free of surfactants, as well as surfaces covered with surfactant monolayers. A soluble and an insoluble monolayer were investigated, Triton X-100 and oleyl alcohol, respectively. Oleyl alcohol was investigated for concentrations ranging from 0 to 0.495 μg/cm2, and Triton X-100 was investigated for concentrations ranging from 0 to 4.0 mg/L. For both surfactants the vortex velocity displayed a maximum at intermediate surfactant concentrations. In all cases the drop fluid was free of surfactants. A possible mechanism based on capillary wave damping is presented to explain these results. The relevance of this work to rain over lakes and oceans is discussed.
Apparent slip flows in hydrophilic and hydrophobic microchannels
Authors: Choi Chang-Hwan , Westin K. Johan A. , Breuer Kenneth S.
Published: September 2003

The slip effects of water flow in hydrophilic and hydrophobic microchannels of 1 and 2 μm depth are examined experimentally. High-precision microchannels were treated chemically to enhance their hydrophilic and hydrophobic properties. The flow rates of pure water at various applied pressure differences for each surface condition were measured using a high-precision flow metering system and compared to a theoretical model that allows for a slip velocity at the solid surface. The slip length was found to vary approximately linearly with the shear rate with values of approximately 30 nm for the flow of water over hydrophobic surfaces at a shear rate of 105 s−1. The existence of slip over the hydrophilic surface remains uncertain, due to the sensitivity of the current analysis to nanometer uncertainties in the channel height.
Simultaneous production of spin-polarized ions/electrons based on two-photon ionization of laser-ablated metallic atoms
Authors: Nakajima Takashi , Yonekura Nobuaki , Matsuo Yukari , Kobayashi Tohru , Fukuyama Yoshimitsu
Published: September 2003

We demonstrate the simultaneous production of spin-polarized ions/electrons using two-color, two-photon ionization of laser-ablated metallic atoms. Specifically, we have applied the developed technique to laser-ablated Sr atoms, and found that the electron-spin polarization of Sr+ ions, and accordingly, the spin polarization of photoelectrons is 64%±9%, which is in good agreement with the theoretical prediction we have recently reported [T. Nakajima and N. Yonekura, J. Chem. Phys. 117, 2112 (2002)]. Our experimental results open up a simple way toward the construction of a spin-polarized dual ion/electron source.
Alexander Lecture 2003: Cubosomes, Vesicles, and Perforated Bilayers in Aqueous Systems of Lipids, Polymers, and Surfactants
Authors: Almgren Mats
Published: September 2003

Cryo-Transmission Electron Microscopy (cryoTEM) is a method allowing visualization of many of the delicate structures that form by self-assembly of amphiphilic molecules in aqueous environments. The amphiphiles may be surfactants, lipids, or polymers, alone or in various mixtures. The distinctive feature of the method is that the objects are examined without staining or dehydration: This is achieved by capturing the structures in very thin aqueous films, that are subsequently vitrified at liquid nitrogen temperatures and examined using a microscope. Objects in the size range from 5 to 500 nm are well suited for the method. This includes various emulsion particles, such as liposomes, and more exotic cubosomes and hexasomes. In cryoTEM investigations perforated vesicles were found, an observation that triggered extensive studies of the nature and occurrence of such structures. As a complement to scattering methods, cryoTEM has proven its value in investigations of the size and morphology of various liposomal and vesicular systems. The microscopy studies show what type of structures that are present in the sample: uni- or multilamellar vesicles, open structures or closed defect-free vesicles, whether the form is spherical, tubular, or oblate, and so on. The scattering methods give good measures of size and polydispersity for defined systems.Three main themes are presented here. (a) Morphology of cubosomes and other emulsion particles from dispersed liquid-crystalline phases. (b) Perforated bilayers, their structure, nature, occurrence, and formation. (c) Spontaneous catanionic vesicles and their relationship to vesicles of zwitterionic lipids plus ionic surfactants.
Revisions and additions to Caulerpa (Chlorophyta, Caulerpaceae) from the Fiji Islands, South Pacific
Authors: South G. Robin , Skelton Posa A.
Published: September 2003

Twenty-three taxa of Caulerpa Lamouroux are listed from the Fiji Islands, including Caulerpa reniformis sp. nov. and four taxa newly recorded [Caulerpa biserrulata Sonder, Caulerpa nummularia Harvey ex J.Agardh, Caulerpa racemosa var. lamourouxii (Turner) Weber-van Bosse and Caulerpa webbiana f. disticha Vickers]. A further four taxa are listed as Species inquirendae [C. crassifolia (C.Agardh) J.Agardh, C. juniperoides J.Agardh. C. mexicana var. pluriseriata W.R.Taylor and C. remotifolia Sonder]. A revised key to the species of Caulerpa from the Fiji Islands is presented. Verification of records is based on the personal collections of the authors and specimens housed in the Phycological Herbarium, South Pacific Regional Herbarium (SUVA-A), the University of British Columbia (UBC), the Bernice P. Bishop Museum (BISH) and the University of California at Berkeley (UC).
Acroplaxome, an F-Actin–Keratin-containing Plate, Anchors the Acrosome to the Nucleus during Shaping of the Spermatid Head
Authors: Kierszenbaum Abraham L. , Rivkin Eugene , Tres Laura L.
Published: August 2003

Nuclear shaping is a critical event during sperm development as demonstrated by the incidence of male infertility associated with abnormal sperm ad shaping. Herein, we demonstrate that mouse and rat spermatids assemble in the subacrosomal space a cytoskeletal scaffold containing F-actin and Sak57, a keratin ortholog. The cytoskeletal plate, designated acroplaxome, anchors the developing acrosome to the nuclear envelope. The acroplaxome consists of a marginal ring containing keratin 5 10-nm-thick filaments and F-actin. The ring is closely associated with the leading edge of the acrosome and to the nuclear envelope during the elongation of the spermatid head. Anchorage of the acroplaxome to the gradually shaping nucleus is not disrupted by hypotonic treatment and brief Triton X-100 extraction. By examining spermiogenesis in the azh mutant mouse, characterized by abnormal spermatid/sperm head shaping, we have determined that a deformity of the spermatid nucleus is restricted to the acroplaxome region. These findings lead to the suggestion that the acroplaxome nucleates an F-actin–keratin-containing assembly with the purpose of stabilizing and anchoring the developing acrosome during spermatid nuclear elongation. The acroplaxome may also provide a mechanical planar scaffold modulating external clutching forces generated by a stack of Sertoli cell F-actin–containing hoops encircling the elongating spermatid nucleus.
Modelling approaches in biomechanics
Authors: Alexander R. McN
Published: September 2003

Conceptual, physical and mathematical models have all proved useful in biomechanics. Conceptual models, which have been used only occasionally, clarify a point without having to be constructed physically or analysed mathematically. Some physical models are designed to demonstrate a proposed mechanism, for example the folding mechanisms of insect wings. Others have been used to check the conclusions of mathematical modelling. However, others facilitate observations that would be difficult to make on real organisms, for example on the flow of air around the wings of small insects. Mathematical models have been used more often than physical ones. Some of them are predictive, designed for example to calculate the effects of anatomical changes on jumping performance, or the pattern of flow in a 3D assembly of semicircular canals. Others seek an optimum, for example the best possible technique for a high jump. A few have been used in inverse optimization studies, which search for variables that are optimized by observed patterns of behaviour. Mathematical models range from the extreme simplicity of some models of walking and running, to the complexity of models that represent numerous body segments and muscles, or elaborate bone shapes. The simpler the model, the clearer it is which of its features is essential to the calculated effect.
Bipedalism in lizards: whole–body modelling reveals a possible spandrel
Authors: Aerts Peter , Damme Raoul Van , D'Août Kristiaan , Hooydonck Bieke Van
Published: September 2003

This paper illustrates how simple mechanical models based on morphological, ethological, ecological and phylogenetic data can add to discussions in evolutionary biology. Bipedal locomotion has evolved on numerous occasions in lizards. Traits that appear repeatedly in independent evolutionary lines are often considered adaptive, but the exact advantages of bipedal locomotion in lizards remain debated. Earlier claims that bipedalism would increase maximal running speed or would be energetically advantageous have been questioned. Here, we use ‘whole body’ mechanical modelling to provide an alternative solution to the riddle. The starting point is the intermittent running style combined with the need for a high manoeuvrability characterizing many small lizard species. Manoeuvrability benefits from a caudal shift of the centre of mass of the body (body–COM), because forces to change the heading and to align the body to this new heading do not conflict with each other. The caudally situated body–COM, however, might result in a lift of the front part of the body when accelerating (intermittent style), thus resulting in bipedal running bouts. Based on a momentum–impulse approach the effect of acceleration is quantified for a mechanical model, a virtual lizard (three segments) based on the morphometrics ofAcanthodactylus erythrurus(a small lacertid lizard). Biologically relevant input (dimensions, inertial properties, step cycle information, etc.) results in an important lift of the front part of the body and observable distances passively covered bipedally as a consequence of the acceleration. In this way, no functional explanation of the phenomenon of lizard bipedalism is required and bipedalism can probably be considered non–adaptive in many cases. This does not exclude, however, some species that may have turned this consequence to their benefit. For instance, instantaneous manipulation of the position of the centre of the body–COM allows stable, persisting bipedal running. Once this was achieved, the bipedal spandrel could be exploited further.
Oscillations of plants' stems and their damping: theory and experimentation
Authors: Brüchert Franka , Speck Olga , Spatz Hanns–Christof
Published: September 2003

Free oscillations of upright plants' stems, or in technical terms slender tapered rods with one end free, can be modelled by considering the equilibrium between bending moments and moments resulting from inertia. For stems with apical loads and negligible mass of the stem and for stems with finite mass but without top loading, analytical solutions of the differential equations with appropriate boundary conditions are available for a finite number of cases. For other cases approximations leading to an upper and a lower estimate of the frequency of oscillation ω can be derived. For the limiting case of ω = 0, the differential equations are identical with Greenhill's equations for the stability against Euler buckling of slender poles. To illustrate, the oscillation frequencies of 25 spruce trees (Picea sitchensis(Bong.) Carr.) were compared with those calculated on the basis of their morphology, their density and their static elasticity modulus. ForArundo donaxL. andCyperus alternifoliusL. the observed oscillation frequency was used in turn to calculate the dynamic elasticity modulus, which was compared with that determined in three–point bending. Oscillation damping was observed forA. donaxandC. alternifoliusfor plants' stems with and without leaves or inflorescence. InC. alternifoliusthe difference can be attributed to the aerodynamic resistance of the leaves, whereas inA. donaxstructural damping in addition plays a major role.
Salt Stress Activation of Wound-Related Genes in Tomato Plants
Authors: Dombrowski James E.
Published: August 2003

Plants respond to various stresses by expressing distinct sets of genes. The effects of multiple stresses on plants and their interactions are not well understood. We have discovered that salt stress causes the accumulation of proteinase inhibitors and the activation of other wound-related genes in tomato (Lycopersicon esculentum) plants. Salt stress was also found to enhance the plant's response to wounding locally and systemically. The tomato mutant (def-1), which has an impairment in the octadecanoid pathway, displayed a severe reduction in the accumulation of proteinase inhibitors under salt stress, indicating that salt stress-induced accumulation of proteinase inhibitors was jasmonic acid dependent. The analysis of salt stress in another tomato mutant, spr-1, which carries a mutation in a systemin-specific signaling component, and transgenic tomato plants that express an antisense-prosystemin cDNA, showed that prosystemin activity was not required for the salt-induced accumulation of proteinase inhibitors, but was necessary to achieve maximal levels. These results suggest that a prosystemin independent- but jasmonic acid-dependent pathway is utilized for proteinase inhibitor accumulation in response to salt stress.
Convergence of Signaling Pathways Induced by Systemin, Oligosaccharide Elicitors, and Ultraviolet-B Radiation at the Level of Mitogen-Activated Protein Kinases in Lycopersicon peruvianum Suspension-Cultured Cells
Authors: Holley Susan R. , Yalamanchili Roopa D. , Moura Daniel S. , Ryan Clarence A. , Stratmann Johannes W.
Published: August 2003

We tested whether signaling pathways induced by systemin, oligosaccharide elicitors (OEs), and ultraviolet (UV)-B radiation share common components in Lycopersicon peruvianum suspension-cultured cells. These stress signals all induce mitogen-activated protein kinase (MAPK) activity. In desensitization assays, we found that pretreatment with systemin and OEs transiently reduced the MAPK response to a subsequent treatment with the same or a different elicitor. In contrast, MAPK activity in response to UV-B increased after pretreatment with systemin and OEs. These experiments demonstrate the presence of signaling components that are shared by systemin, OEs, and UV-B. Based on desensitization assays, it is not clear if the same or different MAPKs are activated by different stress signals. To identify specific stress-responsive MAPKs, we cloned three MAPKs from a tomato (Lycopersicon esculentum) leaf cDNA library, generated member-specific antibodies, and performed immunocomplex kinase assays with extracts from elicited L. peruvianum cells. Two highly homologous MAPKs, LeMPK1 and LeMPK2, were activated in response to systemin, four different OEs, and UV-B radiation. An additional MAPK, LeMPK3, was only activated by UV-B radiation. The common activation of LeMPK1 and LeMPK2 by many stress signals is consistent with the desensitization assays and may account for substantial overlaps among stress responses. On the other hand, MAPK activation kinetics in response to elicitors and UV-B differed substantially, and UV-B activated a different set of LeMPKs than the elicitors. These differences may account for UV-B-specific responses.
Induction of Hypersensitive Cell Death by Hydrogen Peroxide Produced through Polyamine Degradation in Tobacco Plants
Authors: Yoda Hiroshi , Yamaguchi Yube , Sano Hiroshi
Published: August 2003

Screening immediate-early responding genes during the hypersensitive response (HR) against tobacco mosaic virus infection in tobacco (Nicotiana tabacum) plants, we identified a gene encoding ornithine decarboxylase. Subsequent analyses showed that other genes involved in polyamine biosynthesis were also up-regulated, resulting in the accumulation of polyamines in apoplasts of tobacco mosaic virus-infected leaves. Inhibitors of polyamine biosynthesis, α-difluoromethyl-ornithine, however, suppressed accumulation of polyamines, and the rate of HR was reduced. In contrast, polyamine infiltration into a healthy leaf induced the generation of hydrogen peroxide and simultaneously caused HR-like cell death. Polyamine oxidase activity in the apoplast increased up to 3-fold that of the basal level during the HR, and its suppression with a specific inhibitor, guazatine, resulted in reduced HR. Because it is established that hydrogen peroxide is one of the degradation products of polyamines, these results indicate that one of the biochemical events in the HR is production of polyamines, whose degradation induces hydrogen peroxide, eventually resulting in hypersensitive cell death.
Dithiol Oxidant and Disulfide Reductant Dynamically Regulate the Phosphorylation of Light-Harvesting Complex II Proteins in Thylakoid Membranes
Authors: Martinsuo Päivi , Pursiheimo Saijaliisa , Aro Eva-Mari , Rintamäki Eevi
Published: September 2003

Light-induced phosphorylation of light-harvesting chlorophyll a/b complex II (LHCII) proteins in plant thylakoid membranes requires an activation of the LHCII kinase via binding of plastoquinol to cytochrome b  6  f complex. However, a gradual down-regulation of LHCII protein phosphorylation occurs in higher plant leaves in vivo with increasing light intensity. This inhibition is likely to be mediated by increasing concentration of thiol reductants in the chloroplast. Here, we have determined the components involved in thiol redox regulation of the LHCII kinase by studying the restoration of LHCII protein phosphorylation in thylakoid membranes isolated from high-light-illuminated leaves of pumpkin (Cucurbita pepo), spinach (Spinacia oleracea), and Arabidopsis. We demonstrate an experimental separation of two dynamic activities associated with isolated thylakoid membranes and involved in thiol regulation of the LHCII kinase. First, a thioredoxin-like compound, responsible for inhibition of the LHCII kinase, became tightly associated and/or activated within thylakoid membranes upon illumination of leaves at high light intensities. This reducing activity was completely missing from membranes isolated from leaves with active LHCII protein phosphorylation, such as dark-treated and low-light-illuminated leaves. Second, hydrogen peroxide was shown to serve as an oxidant that restored the catalytic activity of the LHCII kinase in thylakoids isolated from leaves with inhibited LHCII kinase. We propose a dynamic mechanism by which counteracting oxidizing and reducing activities exert a stimulatory and inhibitory effect, respectively, on the phosphorylation of LHCII proteins in vivo via a novel membrane-bound thiol component, which itself is controlled by the thiol redox potential in chloroplast stroma.
The analytic nursery: Ferenczi's ‘wise baby’ meets Jung's ‘divine child’
Authors: Fortune Christopher
Published: August 2003

In 1923, Sandor Ferenczi wrote a paper entitled ‘The dream of the clever baby’, in which he identified a phenomenon he discovered through his clinical work: the notion that young children who had been traumatized often had accelerated developmental characteristics that led them to acquire highly acute sensitivities and intuitions – in short, wisdom beyond their years. He characterized them as ‘wise’ babies. Similarly, C. G. Jung, with Karl Kerenyi, (1949) elaborated a myth known as the ‘divine child’– identifying an archetype which activates healing and intuitive understanding in children and adults. In their work, Jung (and Kerenyi) explored the ‘divine child’ archetype from a mythological and a psychological perspective. The following paper elaborates aspects of Ferenczi's ‘wise child’ and Jung's ‘divine child’, comparing and contrasting them, and suggesting new perspectives on the connections between Ferenczi's and Jung's theoretical and clinical perspectives, and the two men themselves. As well, and specifically, the paper explores a comparative understanding of the development of two different modalities of early psychodynamic concepts with regard to children and their response to trauma, aspects that continue through theoretical and clinical practice today.
Strengthening Sociometric Prediction: Scientific Advances in the Assessment of Children's Peer Relations
Authors: DeRosier Melissa E. , Thomas James M.
Published: September 2003

This study assessed the strength of sociometric classification in the prediction of concurrent sociobehavioral adjustment. Differential adjustment for subgroups of unclassified children were also examined. Participants were 881 fifth graders (ages 9 to 12). Classification strength (CS) and unclassified subgroups were determined through newly developed algorithms. CS added significantly to the prediction of all areas of adjustment. For example, highly rejected children were at extreme risk for victimization whereas highly controversial children were most likely to be bullies and relationally aggressive. Unclassified subgroups were found to exhibit adjustment problems mirroring those of their extreme status group counterparts. Findings support that increasing the sensitivity of sociometric measurement results in both greater predictive strength and enhanced understanding of underlying social processes.
Probabilistic Risk Analysis for a High‐Level Radioactive Waste Repository
Authors: Cohen Bernard L.
Published: September 2003

A probabilistic risk analysis (PRA) for a high‐level radioactive waste repository is very important since it gives an estimate of its health impacts, allowing comparisons to be made with the health impacts of competing technologies. However, it is extremely difficult to develop a credible PRA for a specific repository site because of large uncertainties in future climate, hydrology, geological processes, etc. At best, such a PRA would not be understandable to the public. An alternative proposed here is to develop a PRA for an average U.S. site, taking all properties of the site to be the U.S. average. The results are equivalent to the average results for numerous randomly selected sites. Such a PRA is presented here; it is easy to understand, and it is not susceptible to substantial uncertainty. Applying the results to a specific repository site then requires only a simple, intuitively acceptable “leap of faith” in assuming that with large expenditures of effort and money, experts can select a site that would be at least as secure as a randomly selected site.
Statewide Trial‐Heat Polls and the 2000 Presidential Election: A Forecast Model*
Authors: DeSart Jay A. , Holbrook Thomas M.
Published: August 2003

Objective. We provide an examination and update of a presidential election forecasting model that we have previously developed to predict state‐level presidential election outcomes.

Method. Our model consists of September statewide trial‐heat polls in 1992, 1996, and 2000 along with a prior vote variable. We use this model to generate predictions for both state‐level and national‐level outcomes.

Results. Although our model generated reasonably accurate point estimates of state‐level outcomes in 2000, it still incorrectly predicted a Gore victory in 2000.

Conclusions. We discuss possible explanations for the 2000 misprediction and present updated coefficients to be used to generate a forecast for the 2004 election.
Welfare Reform's Chilling Effects on Noncitizens: Changes in Noncitizen Welfare Recipiency or Shifts in Citizenship Status?*
Authors: Van Hook Jennifer
Published: August 2003

Objective. In the mid‐1990s, welfare usage declined disproportionately among noncitizens, prompting some policy analysts to argue that the 1996 Welfare Reform Act (PRWORA) had a “chilling” effect on welfare receipt among eligible non‐citizens. However, naturalization among noncitizen welfare recipients could account for the disproportionate decline. This article evaluates the role of naturalizations in producing the so‐called chilling effect.

Methods. The research uses longitudinal data (the Survey of Program Dynamics) to decompose changes in citizen and noncitizen welfare receipt into parts due to shifts in citizenship status and shifts in welfare receipt.

Results. A substantial portion of the relative decline in welfare usage among noncitizens can be explained by shifts in naturalization.

Conclusions. A more cautious interpretation of results about the effects of welfare reform on immigrants is called for, particularly results of analyses that use cross‐sectional data and disaggregate the change in welfare receipt by citizenship status.
American Regulatory Policy: Factors Affecting Trends Over the Past Century
Authors: Vocino Thomas
Published: August 2003

This article examines American regulatory policy over the past century and the factors that have affected its development. Among the trends analyzed are the movement away from independent regulatory commissions, the larger role played by the institutional presidency vis‐a‐vis the Congress in the regulatory arena, and the growing resistance of states and localities to national government regulation and “unfunded mandates.”
Method to characterize the three-dimensional distribution of focused ion beam induced damage in silicon after 50 keV Ga+ irradiation
Authors: Lugstein A. , Brezna W. , Hobler G. , Bertagnolli E.
Published: September 2003

In this article we report the straggling of long-range implantation damage in silicon in the forefront of a focused ion beam induced amorphization zone. Irradiation was carried out at room temperature at a current density of 0.75 A cm−2 (5×1018 ions/cm2 s) using 50 keV Ga+ ions. A highly sensitive tool for detection, an n-metal–oxide–semiconductor field effect transistor is used to quantify and to characterize the distribution profile of ion beam induced electroactive defects. Scanning the beam over active devices allows the extraction of a three-dimensional profile of defects. In situ monitoring of the drive current and intermitting charge pumping measurements revealed the progressive nature of the damage, the generation of interface states, and the lateral extension of irradiation related defects. Far reaching damage cascades extend at least 300 nm in the beam direction and about 220 nm perpendicular to the beam direction of the substrate and define the region of electrically active defects due to particle beam exposure. The long range of the implantation damage is confirmed by binary collision simulations that take the crystallinity of the target into account.
Corrosion behavior of sputter-deposited TiN thin films
Authors: Martı́n-Palma R. J. , Manso M. , Martı́nez-Duart J. M. , Conde A. , Damborenea J. J.
Published: September 2003

Very thin (∼100 nm), magnetron sputtered TiN films show excellent anticorrosion behavior with a corrosion current of the order of nA/cm2 in a 0.6 M NaCl solution in the passive stage, a dissolution rate of 43.5 nm/yr, and no signs of breakdown or the potential for pitting. These excellent properties are attributed to the absence of pinholes or micropores in the structure. The results obtained by the electrochemical impedance technique show almost perfect capacitive behavior of the films over a wide range of frequencies. Modeling of the results by a series-parallel RC circuit gave excellent results, i.e., close to those of an ideal capacitor for series resistance, parallel resistance and the relative dielectric constant.
Inelastic collisions of electrons and positrons in solids and the dawn of surface science
Authors: Duke C. B.
Published: September 2003

Recognition of the consequences of the creation of collective excitations (e.g., plasmons) of the valence electrons in a solid by “low-energy,” i.e., 50–500 eV, electrons led to a reformulation of the theory of electron solid scattering, the use of electron spectroscopies for surface characterization, the rise of surface science as a recognized interdisciplinary research area, and the emergence of the American Vacuum Society as a major international scientific society. These transformations occurred between 1968 and 1973. This recognition and the concomitant advances in electron-solid scattering theory were extended to positron-solid scattering during the following decade. By virtue of these developments, low-energy electron and positron diffraction became the techniques of choice for determining the detailed geometries of the top few atomic layers of single-crystal solid surfaces.
Surface science 1964–2003
Authors: Duke C. B.
Published: September 2003

This article is the introduction to the surface science section of the fiftieth anniversary issue of the Journal of Vacuum Science and Technology. It highlights the role of AVS in the rise of surface science as an identifiable interdisciplinary research area and sets the context for the four articles in this section of the anniversary issue.
Nanofabrication
Authors: Marrian Christie R. K. , Tennant Donald M.
Published: September 2003

In this the 50th anniversary year of the AVS and the AVS Symposium, this article is offered as one in a series of topical review articles to celebrate the role of this community to the progress in nanofabrication technology. The emphasis of the article is on the principles and limits of the various pattern formation techniques which have emerged as important tools in the research of nanoscale devices and structures. Topics such as e-beam lithography, proximal probes, imprint lithography, self assembly, and directed assembly are all discussed.
Nanoscience and its relationship to the AVS
Authors: Murday James S.
Published: September 2003

Nanometer structures have played a role in technology for millennia, but empirically derived. The invention of surface analytical tools in the 1960s/70s enabled science with one dimension in the nanometer range; commercial products based on that science are significant and growing. The invention of the proximal probes (scanning tunneling microscopy, atomic force microscopy) has stimulated science with all dimensions—0 (dots, clusters, macromolecules), 1 (wires, tubes), 2 (vicinal surfaces), 3 (nanostructured composites)—in the nanometer range. The U.S. National Nanotechnology Initiative, and its equivalents in other countries, seek to accelerate progress in the scientific phase of discovery and invention, and to transition rapidly those innovations into technological opportunities. Building on its foundations in surface science, surface analysis, and electronics materials processing, the AVS has played a significant role in first creating and then promoting that progress.
Fluorinated amorphous carbon films prepared by plasma enhanced chemical vapor deposition for solar cell applications
Authors: Valentini L. , Salerni V. , Armentano I. , Kenny J. M. , Lozzi L. , Santucci S.
Published: September 2003

Heterojunction diodes fabricated by plasma enhanced chemical vapor deposition of hydrogenated amorphous carbon (a-C:H) and fluorine doped amorphous carbons (a-C:H:F) on p-type silicon are analyzed in terms of their electronic and photovoltaic properties. Their structural and optical properties were identified by Raman spectroscopy, x-ray photoelectron spectroscopy, ellipsometry, and UV–VIS trasmittance. The nature of the heterojunction is confirmed by the rectifying current–voltage characteristic of the carbonaceous deposits/p-Si junction. The diodes show a behavior dependent on the amount of the fluorine content. The photovoltaic behavior of the junction is investigated as a function of both fluorine incorporation and thermal treatment of the a-C:H:F films after the deposition. Better photovoltaic effects were observed from annealed a-C:H:F heterojunction structures. The optical and structural characterization performed on films after the thermal treatment indicates that this behavior is most likely due to an extended graphitization.
How hot is radiation?
Authors: Essex Christopher , Kennedy Dallas C. , Berry R. Stephen
Published: September 2003

A self-consistent approach to defining nonequilibrium radiation temperature is discussed using the distribution of the energy over microstates. We begin rigorously with ensembles of Hilbert spaces and end with practical examples based mainly on the far from equilibrium radiation of lasers. We show that very high, but not infinite, laser radiation temperatures depend on intensity and frequency. Heuristic definitions of temperature derived from a misapplication of equilibrium arguments are shown to be incorrect. More general conditions for the validity of nonequilibrium temperatures also are established.
Transport of dsRNA into Cells by the Transmembrane Protein SID-1
Authors: Feinberg Evan H. , Hunter Craig P.
Published: September 2003

RNA interference (RNAi) spreads systemically in plants and nematodes to silence gene expression distant from the site of initiation. We previously identified a gene,
sid-1
, essential for systemic but not cell-autonomous RNAi in
Caenorhabditis elegans
. Here, we demonstrate that SID-1 is a multispan transmembrane protein that sensitizes
Drosophila
cells to soaking RNAi with a potency that is dependent on double-stranded RNA (dsRNA) length. Further analyses revealed that SID-1 enables passive cellular uptake of dsRNA. These data indicate that systemic RNAi in
C. elegans
involves SID-1–mediated intercellular transport of dsRNA.
CF45-1, a Secreted Protein Which Participates in
Dictyostelium
Group Size Regulation
Authors: Brock Debra A. , Hatton R. Diane , Giurgiutiu Dan-Victor , Scott Brenton , Jang Wonhee , Ammann Robin , Gomer Richard H.
Published: August 2003

Developing
Dictyostelium
cells aggregate to form fruiting bodies containing typically 2 × 10
4
cells. To prevent the formation of an excessively large fruiting body, streams of aggregating cells break up into groups if there are too many cells. The breakup is regulated by a secreted complex of polypeptides called counting factor (CF). Countin and CF50 are two of the components of CF. Disrupting the expression of either of these proteins results in cells secreting very little detectable CF activity, and as a result, aggregation streams remain intact and form large fruiting bodies, which invariably collapse. We find that disrupting the gene encoding a third protein present in crude CF, CF45-1, also results in the formation of large groups when cells are grown with bacteria on agar plates and then starve. However, unlike

countin
−

and

cf50
−

cells,

cf45-1
−

cells sometimes form smaller groups than wild-type cells when the cells are starved on filter pads. The predicted amino acid sequence of CF45-1 has some similarity to that of lysozyme, but recombinant CF45-1 has no detectable lysozyme activity. In the exudates from starved cells, CF45-1 is present in a ∼450-kDa fraction that also contains countin and CF50, suggesting that it is part of a complex. Recombinant CF45-1 decreases group size in colonies of

cf45-1
−

cells with a 50% effective concentration (EC
50
) of ∼8 ng/ml and in colonies of wild-type and

cf50
−

cells with an EC
50
of ∼40 ng/ml. Like

countin
−

and

cf50
−

cells,

cf45-1
−

cells have high levels of cytosolic glucose, high cell-cell adhesion, and low cell motility. Together, the data suggest that CF45-1 participates in group size regulation in
Dictyostelium
.
Lifting Invariants of Projective Subschemes
Authors: Ellia Ph.
Published: August 2003

The lifting invariants of a closed subscheme X ⊂ Pn are the numbers [Formula: see text], where H is a general hyperplane and where f is the restriction map. The lifting invariants measure the obstruction to lift hypersurfaces (of H) containing X ∩ H to hypersurfaces containing X. We first prove a general result (which holds for every X ⊂ Pn ) on the behaviour of the ri's; then we turn to the special case of space curves and, under some special assumptions, we prove vanishing results for the ri's and for the cohomology.
Holomorphic Equivariant Cohomology via a Transversal Holomorphic Vector Field
Authors: Feng Huitao
Published: August 2003

In this paper an analytic proof of a generalization of a theorem of Bismut [1, Theorem 5.1] is given, which says that, when v is a transversal holomorphic vector field on a compact complex manifold X with a zero point set Y, the embedding j:Y→ X induces a natural isomorphism between the holomorphic equivariant cohomology of X via v with coefficients in ξ and the Dolbeault cohomology of Y with coefficients in ξ|Y, where ξ→ X is a holomorphic vector bundle over X.
Multiplicity of Functions On Singular Varieties
Authors: Izawa Takeshi , Suwa Tatsuo
Published: August 2003

Let V be a local complete intersection in a complex manifold W. For a function g on W, we set f = g|V and f′ = g|V′, where V′ denotes the non-singular part of V. For each compact connected component S of the union of the singular set of V and the critical set of f′, we define the virtual multiplicity [Formula: see text] of f at S as the residue of the localization by df′ of the Chern class of the virtual cotangent bundle of V. The multiplicity m(f, S) of f at S is then defined by [Formula: see text], where μ(V, S) is the (generalized) Milnor number of [2]. If S = {p} is an isolated point and if g is holomorphic, we give an explicit expression of [Formula: see text] as a Grothendieck residue on V. In the global situation, where we have a holomorphic map of V onto a Riemann surface, we prove a singular version of a formule of B. Iversen [13].
Computational Geometry Column 44
Authors: O'Rourke Joseph
Published: August 2003

The open problem of whether or not every pair of equal-area polygons has a hinged dissection is discussed.
Parton Cascades in High-Energy Nuclear Collisions
Authors: Müller Berndt
Published: August 2003

This is a review of the parton cascade model (PCM) which provides a QCD-based description of nucleus-nucleus reactions at very high energy. The PCM describes the collision dynamics within the early and dense phase of the reaction in terms of the relativistic, probabilistic transport of perturbative excitations (partons) of the QCD vacuum, combined with the renormalization group flow of the parton virtuality. The current state of numerical implementations of the model, as well as its predictions for nuclear collisions at RHIC and LHC are discussed.