bluuebunny/crossref_metadata_2025 huggingface dataset:
A prospective study of children with head injures: III. Psychiatric sequelae
Authors: Brown Gillian , Chadwick Oliver , Shaffer David , Rutter Michael , Traub Michael
Published: July 2009

SYNOPSIS

A 2¼-year prospective study of children suffering head injury is described. Three groups of children were studied: (a) 31 children with ‘severe’ head injuries resulting in a post-traumatic amnesia (PTA) of at least 7 days; (b) an individually matched control group of 28 children with hospital-treated orthopaedic injuries; and (c) 29 children with ‘mild’ head injuries resulting in a PTA exceeding 1 hour but less than 1 week. A retrospective assessment of the children's pre-accident behaviour was obtained by parental interview and teacher questionnaire immediately after the accident and before the behavioural sequelae of the injury could be known. Further psychiatric assessments were undertaken 4 months, 1 year and 21 years after the initial injury. The mild head injury group showed a raised level of behavioural disturbance before the accident but no increase thereafter. It was concluded that head injuries resulting in a PTA of less than I week did not appreciably increase the psychiatric risk. By contrast, there was a marked increase in psychiatric disorders following severe head injury. The high rate of new disorders in children with severe head injuries who were without disorder before the accident, together with the finding of a dose–response relationship with the severity of brain injury, indicated a causal relationship. However, the development of psychiatric disorders in children with severe head injuries was also influenced by the children's pre-accident behaviour, their intellectual level, and their psychosocial circumstances. With the exception of social disinhibition and a slight tendency for the disorders to show greater persistence over time, the disorders attributable to head injury showed no specific features.
Effect of propranolol and phenothiazines on electrodermal orienting and habituation in schizophrenia
Authors: Gruzelier John , Connolly John , Eves Frank , Hirsch Steven , Zaki Saniha , Weller Malcolm , Yorkston Neil
Published: July 2009

SYNOPSIS

Bilateral electrodermal orienting responses were measured to repeated auditory stimuli in schizophrenic patients and controls. In 3 studies phasic activity to moderate intensity sounds of patients on no drugs or phenothiazines was predominantly hyper- or hypo-responsive. Controls showed moderate or slow habituation. Propranolol was found to facilitate habituation in slow habituators and to reinstate responses in half of non-responders, especially when given as the sole drug. The effects seldom had a counterpart in changes in non-specific responses or levels of skin conductance. Modulatory influences on stimulus and response processing and on lateral asymmetries in responses may underlie propranolol's efficacy in treating schizophrenia.
Latency models: the statistical analysis of response times
Authors: Dunn Graham , Master Din
Published: July 2009

SYNOPSIS

This paper introduces statistical methods suitable for the analysis of response, survival or failure times and, in particular, latencies measured in experiments on the speed of recall of memories. The discussion includes the use of simple descriptive statistics, as well as an explanation of the role of linear-logistic and log-linear models.
The concept of akinesia
Authors: De Ajuriaguerra J. , Marshall Helen
Published: July 2009

Synopsis

The concept of akinesia deserves to be looked at again in the light of recent work on Parkinsonism, particularly those findings which have resulted from the use of L-dopa in Parkinsonian syndromes. Akinesia and bradykinesia are integral parts of such syndromes, at times even constituting their essential element. Akinesia belongs to a group of psychomotor syndromes, the semiology and pathogenesis of which were the subject of numerous discussions at the beginning of this century. As we have pointed out elsewhere, akinesia cannot be defined solely in terms of its own characteristics: it must be understood equally in its paradoxical aspects—‘paradoxical kinesia’ in post-encephalitic Parkinsonism in particular, and ‘paradoxical akinesia’ in Parkinsonian patients treated with L-dopa.
Multicompartmental analysis of amino acids: 1. Preliminary data on concentrations, fluxes, and flow constants of tryptophan in affective illness
Authors: Shaw David M. , Johnson Anthony L. , Tidmarsh Simon F. , Macsweeney David A. , Hewland H. Robyn , Woolcock Norman E.
Published: July 2009

Synopsis

The study of tryptophan metabolism using compartmental analysis suggested differences between males and females, and between control subjects and patients with affective illness, patients treated with tricyclic drugs, and those established on lithium therapy. The total mass of tryptophan in the body may be reduced in people prone to affective disorder, and in depressed patients (ill and well) turnover of tryptophan seemed to be reduced. The reduction of concentration of tryptophan in compartment S2 in affective illness could affect protein synthesis.
Rigidity of the Weyl chamber flow, and vanishing theorems of Matsushima and Weil
Authors: KANAI MASAHIKO
Published: July 2009

The aim of the present paper is to reveal an unforeseen link between the classical vanishing theorems of Matsushima and Weil, on the one hand, and rigidity of the Weyl chamber flow, a dynamical system arising from a higher-rank non-compact Lie group, on the other. The connection is established via ‘transverse extension theorems’: roughly speaking, they claim that a tangential 1-form of the orbit foliation of the Weyl chamber flow that is tangentially closed (and satisfies a certain mild additional condition) can be extended to a closed 1-form on the whole space in a canonical manner. In particular, infinitesimal rigidity of the orbit foliation of the Weyl chamber flow is proved as an application.
Body image and self-esteem in older adulthood
Authors: BAKER LUCIE , GRINGART EYAL
Published: July 2009

Given global population ageing and the fact that Australia is experiencing a significant increase in the proportion of older adults in its population, research into ageing issues has become a national priority. Whilst body image and self-esteem have been empirically linked, the relationship among older adults has been neglected. This study investigated several body-image variables and their relationship to self-esteem in a sample of 148 men and women aged 65–85 years who were living independently in the Perth Metropolitan Area of Western Australia. They completed the ‘Rosenberg Self-Esteem Scale’ and the ‘Multidimensional Body-Self Relations Questionnaire’. The results indicated, contrary to a common misconception, that body-image concerns are significant to self-esteem in older adulthood, but that these vary by age and gender. Whilst women appear to develop various strategies to counter the effects of ageing, men seem to be more negatively affected, particularly in relation to body functioning. The findings shed light on the meaning of body image in older adulthood. A better understanding of the meaning of body image, of the factors that influence the meaning, and of how these relate to older adults' self-esteem may help older adults develop a positive body image that will contribute to psycho-social strengths and enhance their quality of life.
Double standards in US warfare: exploring the historical legacy of civilian protection and the complex nature of the moral-legal nexus
Authors: KAEMPF SEBASTIAN
Published: July 2009

This article investigates how – by breaking with the historical double standards regarding civilian protection in conflicts – by the end of the twentieth century, US warfare has come to comply with International Humanitarian Law (IHL). Yet, civilians are still being killed. This has sparked controversies over what constitutes legitimate targeting practices and as to whether higher levels of civilian protection could be achieved. Through an engagement with these debates, including an exploration of the evolution of the norm of non-combatant immunity with specific reference to US warfare, the article argues that IHL does not provide fully satisfactory answers to these issues as it is too permissive in relation to the killing of civilians. The article proposes that more stringent moral guidelines, such as those underpinning the idea of ‘due care’, have the potential to go much further in providing protection for the innocent in war.
NATO Enlargement post-1989: Successful Adaptation or Decline?
Authors: MICHTA ANDREW A.
Published: July 2009

NATO enlargement after the cold war contributed to the democratic transformation of post-communist states. It failed, however, to generate a larger consensus on the shared mission and to provide the requisite military capabilities. Today, notwithstanding the rhetoric of unity after the 2008 Bucharest summit, NATO struggles to reconcile the out-of-area experience of the Balkan wars with its post-9/11 tasks and the renewed territorial defense concerns raised by the 2008 Russo-Georgian war. Paradoxically, the more NATO has expanded to foster the military–political security of the new democratic states of eastern and south-eastern Europe, the less it seems capable of dealing with real security threats such as Afghanistan. Facing the possible strategic failure of its ISAF mission, NATO needs to re-evaluate the policy track chosen post-1989.
Application of a Generalization of Russo's Formula to Learning from Multiple Random Oracles
Authors: ARPE JAN , MOSSEL ELCHANAN
Published: July 2009

We study the problem of learning k-juntas given access to examples drawn from a number of different product distributions. Thus we wish to learn a function f: {−1, 1}n → {−1, 1} that depends on k (unknown) coordinates. While the best-known algorithms for the general problem of learning a k-junta require running times of nk poly(n, 2k), we show that, given access to k different product distributions with biases separated by γ > 0, the functions may be learned in time poly(n, 2k, γ−k). More generally, given access to t ≤ k different product distributions, the functions may be learned in time nk/tpoly(n, 2k, γ−k). Our techniques involve novel results in Fourier analysis, relating Fourier expansions with respect to different biases, and a generalization of Russo's formula.
Forschungsbericht
Authors: Hebebrand Johannes , Albayrak Özgür , Banaschewski Tobias , Dittmann Ralf , Fegert Jörg M. , Fendrich Heike , Föcker Manuel , Freitag Christine , Gerlach Manfred , von Gontard Alexander , Häßler Frank , Herpertz-Dahlmann Beate , Hinney Anke , Klauck Sabine , von Klitzing Kai , Konrad Kerstin , Laucht Manfred , Moehler Eva , Poustka Fritz , Ravens-Sieberer Ulrike , Resch Franz , Rothenberger Aribert , Graf von Schimmelmann Benno , Schulte-Körne Gerd , Schulte-Markwort Michael , Warnke Andreas
Published: July 2009

Forschungsleistung der deutschen Kinder- und Jugendpsychiatrie, Psychosomatik und Psychotherapie 2003–2008
Residual Brain Processing in the Vegetative State
Authors: Riganello Francesco , Sannita Walter G.
Published: July 2009

Vegetative state (VS) is a clinical condition in the severely brain damaged, characterized by wakefulness but unaccompanied by any evidence of awareness of self or environment, voluntary or purposeful behavioral responses to external stimuli, and communication. A metabolic dysfunction of the frontal-parietal network is thought to be responsible for the “functional disconnection” underlying it. Most subjects recover with or without residual disabilities depending on the extent of brain damage. However, VS persists for over 1 year in about 15% of all cases, with exceptional later recovery; prolonged observation has thus become possible and our perspectives have expanded substantially. In recent years, brain activation in response to painful or emotional stimuli (e.g., the mother’s voice or presence) or under stimulus conditions implying processing at varying levels of functional complexity (including learning and semantic functions) has been documented in unambiguously diagnosed VS subjects by advanced electrophysiological and neuroimaging techniques. Methods, experimental conditions, and the results of studies published in years 2002–2008 are summarized. The extent to which brain activation concomitant to external events reflect brain function remains to be investigated. Today, VS nevertheless appears neither static nor homogeneous. An updated characterization also taking the evidence of residual brain responsiveness into account is due. Research with advanced technologies and sophisticated paradigms of brain activation in VS may help us to understand the basic neural processes underlying human consciousness.
Electrophysiological Correlates of Inductive Generalization
Authors: Li Fuhong , Luo Yuejia , Cao Bihua , Li Hong
Published: July 2009

The cognitive mechanism of inductive generalization has been studied broadly, although the neural correlates are still unclear. In the present study, participants were provided with battery quadruplets. Within each quadruplet, some batteries were charged while others were not. Participants were asked to generate a hypothesis about what kinds of batteries were charged. The results revealed that the reaction times and the latencies of frontal N1 were shorter in the Generalizable condition than in the Nongeneralizable condition. After 420 ms onset of stimuli, the late positive complex (LPC) was increased significantly in the generalizable condition, reflecting a process of hypothesis generation and subsequent updating.
Valence Lasts Longer than Arousal
Authors: Gomez P. , Zimmermann P.G. , Guttormsen Schär S. , Danuser B.
Published: July 2009

How long induced moods last is a critical question for mood research, but has been only poorly addressed to date. In particular, physiological parameters have rarely been included to assess the effectiveness of mood induction procedures. We investigated the persistence of four different moods (positive high-arousal, positive low-arousal, negative high-arousal, and negative low-arousal) induced by film clips during a computer task. We measured subjective affective state, respiration, skin conductance level (SCL), heart rate, and corrugator activity. People who watched the two negative clips reported more negative valence after the task and showed more facial frowning and lower SCL during the task than people who watched the two positive clips. No arousal effects persisted throughout the task. The results suggest that induced changes in the valence dimension of moods are maintained throughout an intervening task and are physiologically best reflected by corrugator activity and SCL, whereas induced changes in the arousal dimension dissipate quickly. The implications of these findings for mood research are discussed.
Empirical Support for Resilience as More than the Counterpart and Absence of Vulnerability and Symptoms of Mental Disorder
Authors: Friborg Oddgeir , Hjemdal Odin , Martinussen Monica , Rosenvinge Jan H.
Published: July 2009

The construct of resilience has been viewed as the direct counterpart of factors jeopardizing mental health, i.e., vulnerability and psychopathology. Any operationalization of resilience, thus, risks lying on the same latent continuum as indicators of mental illness, although indicating their absence. A factor analysis combining items from these measurement domains, followed by analyses of second-order factor scores was performed to test this assumption. A random selection of 1,724 participants (34% response rate) from the general population of Norway responded. All items were discriminated well by their primary factors. A second-order factor analysis extracted two components, which was confirmed on a hold-out sample by confirmatory factor methods. The Resilience Scale for Adults (RSA), which measures protective factors, correlated with both second-order factors. Thus, the RSA shared common variance with vulnerability and psychopathology, as well as being unique from illness indices. A hierarchical regression analysis that tested interactions between vulnerability and resilience further supported the unique contributions of the RSA. Thus, the notion of resilience-protective indicators as solely counterparts of vulnerability and psychopathology is not empirically supported.
Large‐scale instabilities of the lower thermosphere during an active period
Authors: Walterscheid R. L. , Crowley G.
Published: July 2009

We have simulated the high‐latitude thermosphere during active periods with a general circulation model and have examined the instability of the thermospheric polar jets spun up by ion drag. We find that the jets are unstable as a result of strong vertical shears on the bottom side (baroclinic) and strong lateral shears on the flanks (barotropic). We have analyzed the model output for evidence of structures indicative of instability and have found a disturbance in the region of strong vertical shear indicative of baroclinic instability and structures at higher altitudes indicative of barotropic instability. Our finding suggests that it may be possible to understand high‐latitude structures such as density cells in the framework of instabilities. These structures are presently not included in empirical models used for density prediction in the upper atmosphere.
Long surface wave dynamics along a convex bottom
Authors: Didenkulova Ira , Pelinovsky Efim , Soomere Tarmo
Published: July 2009

Long linear wave transformation in a basin of varying depth is studied for a case of a convex bottom profile h(x) ∼ x4/3. This bottom geometry provides the “nonreflecting” wave propagation at least in the framework of the one‐dimensional shallow water equation. In this case, shoaling effects are very strong and wave reflection occurs in the immediate vicinity of the shoreline. The existence of traveling wave solutions (which propagate without reflection) in this geometry is established through construction of a 1:1 transformation of the general 1‐D wave equation to the analogous wave equation with constant coefficients. The general solution of the Cauchy problem consists of two traveling waves propagating in opposite directions and allows a detailed description of the wavefield (vertical displacement and depth‐averaged flow). It is found that generally a zone of weak current is formed between these two waves. Waves are reflected from the coastline so that their profile is inverted with respect to the calm water surface. Long‐wave runup on a beach with this profile is studied for the sine pulse, Korteweg‐de Vries soliton, and N wave. It is shown that in certain cases the runup height along the convex profile is considerably larger than for beaches with a linear slope. The analysis of wave reflection from the border of a shallow coastal area of constant depth and a section with the convex profile shows that a transmitted wave always has a sign‐variable shape. Results of the wave transformation above the convex beach and beaches following a general power law are compared. This simplified model demonstrates the potential importance of the tsunami wave transformation along convex beaches.
Subarctic atmospheric aerosol composition: 2. Hygroscopic growth properties
Authors: Herich Hanna , Kammermann Lukas , Friedman Beth , Gross Deborah S. , Weingartner Ernest , Lohmann Ulrike , Spichtinger Peter , Gysel Martin , Baltensperger Urs , Cziczo Daniel J.
Published: July 2009

Subarctic aerosols were sampled during July 2007 at the Abisko Scientific Research Station Stordalen site in northern Sweden with an instrument setup consisting of a custom‐built Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) connected in series to a single particle mass spectrometer. Aerosol chemical composition in the form of bipolar single particle mass spectra was determined as a function of hygroscopic growth both in situ and in real time. The HTDMA was deployed at a relative humidity of 82%, and particles with a dry mobility diameter of 260 nm were selected. Aerosols from two distinct air masses were analyzed during the sampling period. Sea salt aerosols were found to be the dominant particle group with the highest hygroscopicity. High intensities of sodium and related peaks in the mass spectra were identified as exclusive markers for large hygroscopic growth. Particles from biomass combustion were found to be the least hygroscopic aerosol category. Species normally considered soluble (e.g., sulfates and nitrates) were found in particles ranging from high to low hygroscopicity. Furthermore, the signal intensities of the peaks related to these species did not correlate with hygroscopicity.
Time scale and intensity dependency in multiplicative cascades for temporal rainfall disaggregation
Authors: Rupp David E. , Keim Richard F. , Ossiander Mina , Brugnach Marcela , Selker John S.
Published: July 2009

Multiplicative random cascades (MRCs) can parsimoniously generate highly intermittent patterns similar to those in rainfall. The elemental MRC model parameter is the cascade weight, which determines how rainfall at one scale is partitioned at the next smallest scale in the cascade. While it is known that the probability density of these weights may vary with both time scale and rainfall intensity, nearly all previous studies have considered either time scale or intensity separately. We examined the simultaneous dependency of the weights on both factors and assessed the impacts of explicitly including these dependencies in the MRC model. On the basis of the observed relationships between cascade weights and time scale and intensity, four progressively more “dependent” models were constructed to disaggregate a long time series of daily rainfall to hourly intervals. We found that inclusion of the intensity dependency on the model parameters that generate dry intervals greatly improved performance. For the relatively small range of time scales over which the rainfall was disaggregated, varying model parameters with time scale resulted in minor improvement.
Snowmelt‐induced diel fluxes through the hyporheic zone
Authors: Loheide Steven P. , Lundquist Jessica D.
Published: July 2009

Snowmelt processes result in diel fluctuations in streamflow and stream stage that propagate into riparian aquifers and cause a daily pumping of the hyporheic zone. This diel pumping was observed in stream stage and water table records collected in Tuolumne Meadows, Yosemite National Park, California. A model was developed using Fourier analysis to represent the stream stage fluctuations and a solution to the 1‐D, linearized Boussinesq equation for groundwater flow. The modeling demonstrates that a substantial volume of water is pumped in and out of the aquifer via this process on a daily basis. In addition, since the snowmelt‐induced groundwater fluctuations exhibit both reduced amplitudes and increased time lags at distances away from the stream, the model can be used to estimate the hydraulic parameters of the riparian aquifer. Snowmelt‐induced hyporheic pumping may have implications for biogeochemical processes in the hyporheic zone and may provide important ecosystem services related to water filtration, thermal buffering, nutrient cycling, and water quality. Consideration should be given to recognizing, quantifying, and monitoring snowmelt‐induced pumping of the hyporheic zone and the ecosystem services it provides since climate and land use changes may alter the magnitude of this process in the future.
“Room for river” measures and public visions in the Netherlands: A survey on river perceptions among riverside residents
Authors: de Groot Mirjam , de Groot Wouter T.
Published: July 2009

Dutch river management is moving from traditional dike reinforcements toward “room for river” measures to assure flood protection and to serve other societal goals. With that, the engineering paradigm shifts from mastership over nature to a more partnership‐like attitude toward nature. Are these values shared by Dutch riverside residents? Are the measures proposed under the new paradigm accepted? This paper investigates these two questions on the basis of semistructured interviews and a survey in communities along the floodplain of the river Waal (i.e., Rhine). The analyses show that even though their visions of nature are remarkably ecocentric, partnership with nature is not the dominant idea within that ecocentric realm. Partly as a consequence of that and partly because the respondents do not perceive the measures as natural, the investigated room for river measures are not endorsed.
Questioning Global Vaginahood: Reflections from Adapting The Vagina Monologues in Hong Kong
Authors: Cheng Sealing
Published: July 2009

Drawing on the author's experience in devising a localized version of The Vagina Monologues in Hong Kong, this paper critically appraises the ‘global vaginahood’ in the globalization of The Vagina Monologues and the V-Day movement that reproduces a core-periphery relationship in the transnational women's movement. As a theatrical performance and a worldwide movement, these productions are remarkable for the manner in which they raise awareness about women's sexuality and violence against women in different parts of the world. Critical questions, however, remain on the rhetoric of universalism and the ethnocentric methods of the global campaign, with US women's experiences and agenda defining those of women in other parts of the world. As a worldwide campaign, the V-Day movement reproduces a hierarchical model between the global North and South, with an emphasis on Western leadership rather than coalition between partners with different experiences, priorities, and strategies. The paper argues that feminists may develop more effective coalitions with local women by recognizing and identifying locally derived creative efforts to respond to issues that are pertinent to their lives. As such, the paper is a push for dialogues in the V-Day campaign and transnational women's movement in general.
Re-Negotiating Reproductive Technologies: The ‘Public Foetus’ Revisited
Authors: Firth Georgina
Published: July 2009

In debates over abortion, the foetus and the woman have been continually positioned as antagonists. Given the stakes involved in such debates about personal integrity, individual responsibility, life and death, it is no wonder that many radical feminist authors have concentrated on refocusing the attention on women and away from the disembodied foetus. Such writers have worked hard to decode and deconstruct the public foetus in our midst and have mobilized interpretative tools such as cultural criticism to contextualize the production and consumption of foetal images. Barbara Duden's book, The Public Foetus, is an important and interesting contribution to this effort, which is still taken up by authors writing in this field. Duden's strategy is to seek to remind us (and in particular those who are involved in reproductive medicine) that pregnancy is concentrated in the embedded pregnant woman rather than the disembodied ‘public foetus’ and she attempts to retrieve the embodied woman as the site of pregnancy through what Michaels has termed a ‘fetal disappearing act’. While this may create as many problems for women as it resolves, I would argue that, while the ‘public foetus’ continues to loom large in the politics of abortion and women's positions in relation to the new reproductive technologies remain contested, Duden's work remains important in the continuing debate about how women's reproductive freedom can be continually re-negotiated and re-established.
Surface energy transport following relativistic laser-solid interaction
Authors: Langhoff H. , Bowes B. T. , Downer M. C. , Hou Bixue , Nees J. A.
Published: July 2009

A planar Al target is excited by a 25 fs laser pulse focused to intensity up to 3×1018 W/cm2 in a ∼1 μm radius spot; subsequent heat propagation along the target surface, imaged by a delayed probe pulse, appears as a roughly circular area of reduced reflectivity centered on the pump spot, that expands to as much as 12±3 μm in radius within 500 fs. We present a semiempirical model in which the pump laser pulse drives hot electrons into the target via collisionless interactions. A return current heats the target and, above a critical temperature, includes runaway electrons that return to the surface before dissipating their energy. Ultrafast radial expansion of the heated surface layer is explained by lateral diffusive motion of returning runaway electrons oscillating across the target surface layer confined by space charge. Isotropy of the observed expansion is consistent with dominance of resonance absorption over j×B heating, indicating prepulse heating is important.
Omnidirectional transparency induced by matched impedance in disordered metamaterials
Authors: Sun Wei-Hua , Lu Ye , Peng Ru-Wen , Cao Lu-Shuai , Li De , Wu Xin , Wang Mu
Published: July 2009

In this work, we present an omnidirectional perfect transmission in the photonic band gap of a metamaterial, where positive-index and active negative-index materials are randomly stacked. Due to mismatched impedance, a photonic band gap appears when the metamaterial possesses zero averaged refractive index. By introducing the matched impedance at the expected frequency, a complete tunneling is achieved in the photonic band gap. This kind of transparency is robust against not only incident angles, optical polarization but system disorder as well. The finding is expected to achieve potential applications in optoelectronic devices.
High-pressure powder x-ray diffraction experiments andab initiocalculation of Ti3AlC2
Authors: Zhang Haibin , Wu Xiang , Nickel Klaus Georg , Chen Jixin , Presser Volker
Published: July 2009

The structural stability of the layered ternary carbide Ti3AlC2 was studied up to 35 GPa using x-ray diffraction with a Merrill–Basset-type diamond anvil cell and ab initio calculations. The structure (P63/mmc) was stable in the present pressure range without any phase transition. The Birch–Murnaghan equation of state was employed to fit the experimental pressure-volume date, from which the isothermal bulk modulus of Ti3AlC2 was determined as 156±5 GPa, which was also supported by theoretical results. In addition, theoretical calculations described anisotropic pressure dependences of the lattice parameters, electronic structure, and bonding properties of Ti3AlC2.
Template-based fluoroethylenepropylene piezoelectrets with tubular channels for transducer applications
Authors: Altafim Ruy Alberto Pisani , Qiu Xunlin , Wirges Werner , Gerhard Reimund , Altafim Ruy Alberto Corrêa , Basso Heitor Cury , Jenninger Werner , Wagner Joachim
Published: July 2009

We describe the concept, the fabrication, and the most relevant properties of a piezoelectric-polymer system: Two fluoroethylenepropylene (FEP) films with good electret properties are laminated around a specifically designed and prepared polytetrafluoroethylene (PTFE) template at 300 °C. After removing the PTFE template, a two-layer FEP film with open tubular channels is obtained. For electric charging, the two-layer FEP system is subjected to a high electric field. The resulting dielectric barrier discharges inside the tubular channels yield a ferroelectret with high piezoelectricity. d33 coefficients of up to 160 pC/N have already been achieved on the ferroelectret films. After charging at suitable elevated temperatures, the piezoelectricity is stable at temperatures of at least 130 °C. Advantages of the transducer films include ease of fabrication at laboratory or industrial scales, a wide range of possible geometrical and processing parameters, straightforward control of the uniformity of the polymer system, flexibility, and versatility of the soft ferroelectrets, and a large potential for device applications e.g., in the areas of biomedicine, communications, production engineering, sensor systems, environmental monitoring, etc.
Low-energy Landau levels of Bernal zigzag graphene ribbons
Authors: Huang Y. C. , Chang C. P. , Su W. S. , Lin M. F.
Published: July 2009

Low-energy Landau levels of Bernal zigzag graphene ribbons in the presence of a uniform perpendicular magnetic field (B) are investigated by the Peierls coupling tight-binding model. State energies and associated wave functions are dominated by the B-field strength and the kz-dependent inter-ribbon interactions. The occupied valence bands are asymmetric to the unoccupied conduction bands about the Fermi level. Many doubly degenerate Landau levels and singlet curving magnetobands exist along the kx and kz directions, respectively. The kz-dependent inter-ribbon interactions dramatically modify the magnetobands, such as the lift of double degeneracy, the change in state energies, and the production of two groups of curving magnetobands. They also change the characteristics of the wave functions and cause the redistribution of the charge-carrier density. The kz-dependent wave functions are further used to predict the selection rule of the optical transition.
Persistent photoconductivity and electron paramagnetic resonance in zinc oxide ceramics
Authors: Laiho R. , Poloskin D. S. , Stepanov Yu. P. , Vlasenko M. P. , Vlasenko L. S. , Zakhvalinskii V. S.
Published: July 2009

The effect of persistent photoconductivity is observed in zinc oxide (ZnO) ceramics together with persistence of the electron paramagnetic resonance (EPR) spectra of defects and impurity centers in the samples. The spectral and time dependences of the EPR signals and microwave photoconductivity are investigated under excitation by light with different quantum energies below the ZnO band gap. The mechanisms of the persistent photoconductivity and coexistence of pnotoconductivity and optically induced EPR spectra after switching off the light are discussed. Based on the experimental results it is concluded that surface and intergranular conductivities dominate in ZnO ceramics.
Investigating the role of hydrogen in indium oxide tubular nanostructures as a donor or oxygen vacancy passivation center
Authors: Kumar Mukesh , Chatterjee R. , Milikisiyants S. , Kanjilal A. , Voelskow M. , Grambole D. , Lakshmi K. V. , Singh J. P.
Published: July 2009

Electron paramagnetic resonance (EPR) spectroscopy of hydrogen-doped indium oxide (IO) tubular nanostructures shows presence of paramagnetic oxygen vacancies (VO) at room temperature. For temperatures below 80 K, the EPR spectra exhibit two distinct split resonances correspond to S=12 hydrogen electron spin. Interestingly, presence of hydrogen EPR resonances is accompanied by absence of EPR signal of VO, which is restored above 80 K with the concomitant disappearance of signature resonances from hydrogen. The temperature dependent donor and passivation behavior of hydrogen has been directly observed in metal oxide. This could provide valuable explanations of various VO induced controversial properties of IO nanostructures.
Origins of threshold voltage shifts in room-temperature deposited and annealed a-In–Ga–Zn–O thin-film transistors
Authors: Nomura Kenji , Kamiya Toshio , Hirano Masahiro , Hosono Hideo
Published: July 2009

Threshold voltage (Vth) stability was examined under constant current stress for a-In–Ga–Zn–O thin film transistors (TFTs) deposited at room temperature and annealed at 400 °C in dry or wet O2 atmospheres. All the TFTs exhibited positive Vth shifts (ΔVth) and the ΔVth value was reduced by the thermal annealing to <2 V for 50 h. TFT simulations revealed that the ΔVth for the annealed TFTs is explained by increase in deep charged defects. Large ΔVth over 10 V and deterioration in subthreshold voltage swing were observed in the unannealed TFTs, which are attributed to the increase in shallow trap states.
Field emission from multiwall carbon nanotubes in gas for producing microplasma discharge
Authors: Zou Q. , Wang M. Z. , Yang Y. L.
Published: July 2009

Electron field emission (FE) from multiwall carbon nanotubes (CNTs) in gas (Ar and air) for producing microplasma discharge was measured in a scanning electron microscope. The results showed that the FE properties of the CNTs were stable in Ar and air gases when the FE threshold voltages were lower than the conventional gas breakdown voltages. These results proved the probability that microplasma could be sustained by FE electrons emitted from the CNTs without ion bombardment, which could avoid the damage of the cathode.
Signal transformation approach to fast nanopositioning
Authors: Sebastian Abu , Moheimani S. O. Reza
Published: July 2009

High bandwidth, high resolution positioning is a significant enabling tool for nanotechnology. Unfortunately, in a typical nanopositioner operating in closed loop, higher bandwidth results in increased sensitivity to measurement noise and hence reduced resolution. In this article we present a technique that allows high-precision tracking of repetitive, jitter-free reference signals without being constrained by the reduction in measurement noise induced positioning resolution. The technique works exceptionally well for scanners with high enough open loop bandwidth and in the absence of high frequency external disturbances. Both simulation and experimental results are presented to illustrate this concept using a triangular reference signal.
Characterization of condenser microphones under different environmental conditions for accurate speed of sound measurements with acoustic resonators
Authors: Guianvarc’h Cécile , Gavioso Roberto M. , Benedetto Giuliana , Pitre Laurent , Bruneau Michel
Published: July 2009

Condenser microphones are more commonly used and have been extensively modeled and characterized in air at ambient temperature and static pressure. However, several applications of interest for metrology and physical acoustics require to use these transducers in significantly different environmental conditions. Particularly, the extremely accurate determination of the speed of sound in monoatomic gases, which is pursued for a determination of the Boltzmann constant k by an acoustic method, entails the use of condenser microphones mounted within a spherical cavity, over a wide range of static pressures, at the temperature of the triple point of water (273.16 K). To further increase the accuracy achievable in this application, the microphone frequency response and its acoustic input impedance need to be precisely determined over the same static pressure and temperature range. Few previous works examined the influence of static pressure, temperature, and gas composition on the microphone’s sensitivity. In this work, the results of relative calibrations of 1/4 in. condenser microphones obtained using an electrostatic actuator technique are presented. The calibrations are performed in pure helium and argon gas at temperatures near 273 K and in the pressure range between 10 and 600 kPa. These experimental results are compared with the predictions of a realistic model available in the literature, finding a remarkable good agreement. The model provides an estimate of the acoustic impedance of 1/4 in. condenser microphones as a function of frequency and static pressure and is used to calculate the corresponding frequency perturbations induced on the normal modes of a spherical cavity when this is filled with helium or argon gas.
Radioisotope microbattery based on liquid semiconductor
Authors: Wacharasindhu T. , Kwon J. W. , Meier D. E. , Robertson J. D.
Published: July 2009

A liquid semiconductor-based radioisotope micropower source has been pioneerly developed. The semiconductor property of selenium was utilized along with a 166 MBq radioactive source of S35 as elemental sulfur. Using a liquid semiconductor-based Schottky diode, electrical power was distinctively generated from the radioactive source. Energetic beta radiations in the liquid semiconductor can produce numerous electron hole pairs and create a potential drop. The measured power from the microbattery is 16.2 nW with an open-circuit voltage of 899 mV and a short-circuit of 107.4 nA.
Self-consistent nonstationary two-dimensional model of multipactor in dielectric-loaded accelerator structures
Authors: Sinitsyn O. V. , Nusinovich G. S. , Antonsen T. M.
Published: July 2009

In this paper, a self-consistent nonstationary two-dimensional model of multipactor in dielectric-loaded accelerating structures is proposed. In comparison with existing models, this model calculates dc electric field produced by secondary electrons self-consistently and it also includes effects of cylindricity. Results of our calculations are compared with the ones obtained for the 11.424 GHz alumina-based dielectric-loaded accelerating structure designed and experimentally tested by Argonne National and Naval Research Laboratories.
An improved X-band magnetically insulated transmission line oscillator
Authors: Ju Jin-Chuan , Fan Yu-Wei , Zhong Hui-Huang , Shu Ting
Published: July 2009

This paper presents an improved X-band magnetically insulated transmission line oscillator (MILO) design that addresses several deficiencies found in previous experiments. In the new structure, an improved design of the launch point region is introduced, which improves the electric field uniformity on the cathode surface in order to suppress cathode flare formation. In addition, a new design for the load region is presented where the end of the cathode consists of four polymer velvet rings, a mesh is adopted as the anode of the load, and a metal barrel is employed as the beam dump. These improvements reduce energy deposition in the beam dump to less than 30 J/g, which probably suppresses plasma formation in the load region. Typical simulation results of the improved MILO show that when the applied voltage is 690 kV and beam current is 48 kA, high power microwave with an average power of 3.5 GW and a frequency of 9.26 GHz is generated. Furthermore, new meshes are specially studied for long pulse operation of this improved X-band MILO. Correlative experiments are being carried out in our laboratory.
Transition from dynamic to static disorder in one-dimensional organic semiconductors
Authors: Troisi Alessandro , Cheung David L.
Published: July 2009

A generic model Hamiltonian is proposed for the study of the transport in a quasi-one-dimensional semiconductor in the charge transport regime intermediate between dynamic localization and static localization due to structural disorder. This intermediate regime may be appropriate for many organic semiconductors, including polymers, discotic liquid crystals, and DNA. The dynamics of the charge carrier is coupled to classical Langevin oscillators whose spectral density can be adjusted to model experimental systems of interest. In the proposed model, the density of states is constant (at constant temperature) and the transition from dynamic to static disorder is controlled by a single parameter. This paper further clarifies that the density of states may not contain all the information needed to describe the charge transport in some materials.
Phase space correlation to improve detection accuracy
Authors: Carroll T. L. , Rachford F. J.
Published: July 2009

The standard method used for detecting signals in radar or sonar is cross correlation. The accuracy of the detection with cross correlation is limited by the bandwidth of the signals. We show that by calculating the cross correlation based on points that are nearby in phase space rather than points that are simultaneous in time, the detection accuracy is improved. The phase space correlation technique works for some standard radar signals, but it is especially well suited to chaotic signals because trajectories that are adjacent in phase space move apart from each other at an exponential rate.
Analysis of the electric field induced elemental separation of Ge2Sb2Te5 by transmission electron microscopy
Authors: Kang Dongmin , Lee Dongbok , Kim Hyun-Mi , Nam Sung-Wook , Kwon Min-Ho , Kim Ki-Bum
Published: July 2009

The chemical instability of line patterned Ge2Sb2Te5 was studied by transmission electron microscopy after electrically inducing melt and solidification. Compositional analysis showed elemental separation of Te to the anode side, while Ge and Sb mutually separated at the cathode side. Such elemental separation of Ge2Sb2Te5 is explained by the electric field effects and thermodynamic driving forces.
Phase change behavior in oxygen-incorporated Ge2Sb2Te5 films
Authors: Jang M. H. , Park S. J. , Lim D. H. , Cho M.-H. , Do K. H. , Ko D.-H. , Sohn H. C.
Published: July 2009

Oxygen-incorporated Ge2Sb2Te5 (GST) films were deposited using ion beam sputtering deposition. Sheet resistance in films with 16.7% oxygen content decreased at a higher annealing temperature than that of undoped GST films, while resistance in films with an oxygen content of over 21.7% decreased dramatically at lower temperatures. X-ray diffraction patterns showed crystallization to face-centered cubic phase was suppressed. However, phase separation to a hexagonal structure was observed in films with an oxygen content of over 21.7%. Extended x-ray absorption fine structure data of Ge K edge showed Ge was bonded to O as well as Te. Moreover, a stoichiometric GeO2 phase was not observed, while phase separation into Sb2O3 and Sb2Te3 occurred. The results indicate Ge–Te bonds with oxygen are related to structural stability.
Direct gap photoluminescence of n-type tensile-strained Ge-on-Si
Authors: Sun Xiaochen , Liu Jifeng , Kimerling Lionel C. , Michel Jurgen
Published: July 2009

Room temperature direct gap photoluminescence (PL) was observed from n-type tensile-strained epitaxial Ge-on-Si. The PL intensity increases with n-type doping due to a higher electron population in the direct Γ valley as a result of increased Fermi level. The direct gap emission also increases with temperature due to thermal excitation of electrons into the direct Γ valley, exhibiting robustness to heating effects. These unique properties of direct gap emission in an indirect gap material agree with our theoretical model and make Ge a promising light emitting material in 1550 nm communication band.
Indium-zinc-oxide nanobelts with superlattice structure
Authors: Alemán B. , Fernández P. , Piqueras J
Published: July 2009

Indium-zinc-oxide (IZO) nanobelts have been grown by a thermal evaporation-deposition method with ZnO and In2O3 powders as precursors. The nanobelts have a superlattice structure that is explained by the formation of In–O and In/Zn–O layers, which appears to favor the formation of nanorings. X-ray analytical methods indicate that the approximate composition of the compound is Zn4In2O7. Cathodoluminescence of the nanobelts in scanning electron microscope shows a dominant emission at 2.37 eV, which is suggested to be a characteristic band of the IZO structure.
Tumor suppressor function of laminin-binding α-dystroglycan requires a distinct β3-
N
-acetylglucosaminyltransferase
Authors: Bao Xingfeng , Kobayashi Motohiro , Hatakeyama Shingo , Angata Kiyohiko , Gullberg Donald , Nakayama Jun , Fukuda Michiko N. , Fukuda Minoru
Published: July 2009

α-Dystroglycan (α-DG) represents a highly glycosylated cell surface molecule that is expressed in the epithelial cell-basement membrane (BM) interface and plays an essential role in epithelium development and tissue organization. The α-DG–mediated epithelial cell-BM interaction is often impaired in invasive carcinomas, yet roles and underlying mechanisms of such an impaired interaction in tumor progression remain unclear. We report here a suppressor function of laminin-binding glycans on α-DG in tumor progression. In aggressive prostate and breast carcinoma cell lines, laminin-binding glycans are dramatically decreased, although the amount of α-DG and β-dystroglycan is maintained. The decrease of laminin-binding glycans and consequent increased cell migration were associated with the decreased expression of β3-
N
-acetylglucosaminyltransferase-1 (β3GnT1). Forced expression of β3GnT1 in aggressive cancer cells restored the laminin-binding glycans and decreased tumor formation. β3GnT1 was found to be required for laminin-binding glycan synthesis through formation of a complex with LARGE, thus regulating the function of LARGE. Interaction of the laminin-binding glycans with laminin and other adhesive molecules in BM attenuates tumor cell migratory potential by antagonizing ERK/AKT phosphorylation induced by the components in the ECM. These results identify a previously undescribed role of carbohydrate-dependent cell-BM interaction in tumor suppression and its control by β3GnT1 and LARGE.