bluuebunny/crossref_metadata_2025 huggingface dataset:
Peculiarities of the silica surface center structure in rigid dehydroxidation conditions
Authors: Litinsky A. O. , Perminov V. N. , Vasiljeva G. Y.
Published: September 2006

A model of molecular claster and nonempirical calculation schemes MP2/6‐31G*, MP4/6‐31G*, and MP2/DZVP2 were applied to study electronic and energy characteristics of the surface centers of different SiO2 modifications in rigid dehydroxidation conditions. It was established that depending on an angle α = Si′O′Si″ (where O′ is an oxygen atom of the nearest to the surface layer), O* atom corresponding with two surface Si atoms, could (i) form a chemical bond with one of the Si′ or Si″‐centers (an asymmetric configuration, α > 118° ÷ 120°); or (ii) be common for these centers (a symmetric configuration, α < 118° ÷ 120°). It was also established that when α > 132° ÷ 133°, the basic state was triple and at α < 132° ÷ 133°, it was single. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Synchronicity related to dead loved ones as a natural healing modality
Authors: Todaro‐Franceschi Vidette
Published: September 2006

The purpose of this exploratory descriptive study was to explore the experience of synchronicity (meaningful coincidence) related to dead loved ones and to identify whether these events, when experienced by those who are grieving, help to create opportunities for personal transformation and enhanced well‐being. Nine female adults agreed to participate in the study, which was conducted in a nondenominational community group setting using weekly group sessions, one‐to‐one interviews, and written questionnaires. Several common themes emerged: participants verbalized feeling happy while sad, believing and at the same time disbelieving, being scared and yet reassured, feeling connected but also disconnected, and sometimes having faith while at other times lacking faith. In addition, it was identified that the sharing of synchronicity experiences with other individuals who were grieving contributed positively to the grief‐healing process for the group as a whole. Copyright © 2006 John Wiley & Sons, Ltd.
Assessing the Predictive Accuracy of hMLH1 and hMSH2 Mutation Probability Models
Authors: Jasperson Kory W. , Lowstuter Katrina , Weitzel Jeffrey N.
Published: September 2006

Hereditary nonpolyposis colorectal cancer (HNPCC) is characterized by a susceptibility to colorectal and extra‐colonic cancers. Several guidelines exist for the identification of families suspected of having HNPCC, however these guidelines lack adequate sensitivity and specificity. In an attempt to improve accuracy for the detection of individuals with HNPCC, the Wijnen pre‐test probability model (1998) and Myriad Genetics Laboratory prevalence table (2004) were developed. Here we evaluate the Wijnen model and Myriad table at predicting the presence of a mutation in individuals undergoing genetic testing for HNPCC. Forty‐nine patients who had undergone genetic testing for germline mutations in hMLH1 and/or hMSH2 were part of our analysis. Our results revealed that the revised Bethesda guidelines performed with the highest sensitivity for germline mutations (94.4%), however the specificity was low (12.9%). Using a 10.0% mutation probability threshold, the Wijnen model and Myriad table had sensitivities of 55.6 and 60.0%, respectively and specificities of 54.8 and 23.8%, respectively. The Wijnen model and Myriad table were poor predictors of mutation prevalence, which is shown by the areas underneath their corresponding receiver operator characteristic curves (0.616 and 0.400, respectively). The results of this study demonsrate that neither the Wijnen model nor the Myriad table are sensitive or specific enough to be used as the only indication when to offer genetic testing for HNPCC.
Shedding of procoagulant microparticles from unstimulated platelets by integrin‐mediated destabilization of actin cytoskeleton
Authors: Cauwenberghs Sandra , Feijge Marion A.H. , Harper Alan G.S. , Sage Stewart O. , Curvers Joyce , Heemskerk Johan W.M.
Published: September 2006

Platelet activation by potent, Ca2+‐mobilizing agonists results in shedding of microparticles that are active in coagulation. Here we show that platelets under storage produce procoagulant microparticles in the absence of agonist. Microparticle formation by resting platelets results from αIIbβ3 signaling to destabilization of the actin cytoskeleton in the absence of calpain activation. Integrin‐mediated spreading of platelets over fibrinogen similarly results in microparticle formation. After transfusion of stored platelet preparations to thrombocytopenic patients, the microparticles contribute to coagulant activity in vivo.
Paneth cell antimicrobial peptides: Topographical distribution and quantification in human gastrointestinal tissues
Authors: Wehkamp Jan , Chu Hiutung , Shen Bo , Feathers Ryan W. , Kays Robert J. , Lee Sarah K. , Bevins Charles L.
Published: September 2006

Antimicrobial peptides and proteins are key effectors of innate immunity, expressed both by circulating phagocytic cells and by epithelial cells of mucosal tissues. In the human small intestine, Paneth cells are secretory epithelial cells that express the antimicrobials human α‐defensin‐5 (HD5), HD6, lysozyme and secretory phospholipase A2 (sPLA2), and recent studies have implicated reduced HD5 and HD6 expression levels in the pathogenesis of ileal Crohn's disease. However, expression levels of these molecules have not been determined routinely by techniques that readily permit quantitative comparisons of their distribution between tissues and samples. Using quantitative real‐time PCR with external standards and Northern blot analysis, we compared expression levels of mRNA encoding these four Paneth cell antimicrobial peptides, as well as circulating human neutrophil defensins in several different gastrointestinal tissues and the bone marrow. HD5 and HD6 were the most abundant antimicrobials expressed in the small intestine. The concentration of HD5 mRNA is approximately 5 × 105 copies per 10 ng RNA in the jejunum and ileum; HD6 mRNA levels were about six times lower than those of HD5. With the exception of low levels in the pancreas (103 copies/10 ng RNA), the expression of HD5 and HD6 in tissues other than small intestine was at or below detectable limits. The expression of sPLA2 and lysozyme mRNA was observed in the small intestine (approximately, 3 × 103 and 9 × 103 copies/10 ng RNA, respectively), but also in several other tissues. Lysozyme expression was high in the duodenum (105 copies/10 ng RNA), and the protein localized to both Brunner's glands in the lamina propria and Paneth cells. By comparison, the hematopoietic α‐defensins HNP1‐3 mRNA were detected at 6 × 105 copies per 10 ng RNA in the bone marrow. These quantitative RT‐PCR data from healthy tissues represents the first quantitative topographical assessment of antimicrobial expression in the gastrointestinal tract and provides a means to directly compare expression levels between healthy tissues and disease specimens for multiple antimicrobial peptides.
Protein‐based phylogenetic analysis by using hydropathy profile of amino acids
Authors: Liu Na , Wang Tianming
Published: September 2006

So far, various approaches for phylogenetic analysis have been developed. Almost all of them put stress on analyzing nucleic acid sequences or protein primary structures. In this paper, we take the physicochemical properties of amino acids into account and introduce the hydropathy profile of amino acids into phylogenetic analysis. We find that this introduction is effectual and our method may be used to complement phylogenetic analysis.
Observation of single‐stranded DNA on mica and highly oriented pyrolytic graphite by atomic force microscopy
Authors: Adamcik Jozef , Klinov Dmitry V. , Witz Guillaume , Sekatskii Sergey K. , Dietler Giovanni
Published: September 2006

Atomic force microscopy was used to image single‐stranded DNA (ssDNA) adsorbed on mica modified by Mg2+, by 3‐aminopropyltriethoxysilane or on modified highly oriented pyrolytic graphite (HOPG). ssDNA molecules on mica have compact structures with lumps, loops and super twisting, while on modified HOPG graphite ssDNA molecules adopt a conformation without secondary structures. We have shown that the immobilization of ssDNA under standard conditions on modified HOPG eliminates intramolecular base‐pairing, thus this method could be important for studying certain processes involving ssDNA in more details.
Spinal cord injury resulting from incorrect microchip placement in a cat
Authors: Platt Simon , Wieczorek Lara , Dennis Ruth , De Stefani Alberta
Published: September 2006

A 2-year-old, male neutered domestic shorthair cat was presented for investigation of an acute onset of tetraparesis immediately following the implantation of a pet identification microchip. A left-sided C6–T2 spinal segment localisation was suspected from the neurological examination, with spinal cord trauma being the primary differential diagnosis. Myelography demonstrated obliteration of the contrast columns by the microchip at the C5–C6 intervertebral disc space. A dorsal laminectomy was undertaken and the microchip was successfully removed. Eleven months after the surgery, the cat was able to weight bear in all limbs but with mild residual paresis in the left thoracic limb.
Magnetostratigraphic dating of an intensification of glacial activity in the southern Italian Alps during Marine Isotope Stage 22
Authors: Muttoni Giovanni , Ravazzi Cesare , Breda Marzia , Pini Roberta , Laj Carlo , Kissel Catherine , Mazaud Alain , Garzanti Eduardo
Published: September 2006

We applied magnetostratigraphy and mammal biostratigraphy to date climate-sensitive pollen cycles and lithostratigraphic units of the Pliocene–Pleistocene Leffe sedimentary succession from the Southern Alps, Italy. The Leffe section was correlated to additional sections (Casnigo, Fornaci di Ranica, and Pianengo) to construct a stratigraphic network along a common fluviatile system (the Serio River) sourced in the Southern Alps and flowing southward into the Po River Basin. We obtained a coherent scenario of climate variability for the last ∼ 2 Myr. At Leffe, lacustrine deposition commenced during the Olduvai Normal Subchron (1.94–1.78 Ma) and lasted up to a chronologic level compatible with Marine Isotope Stage (MIS) 22 (0.87 Ma). Pollen analysis revealed that climate varied cyclically from warm-temperate to cool during this time interval, but never as cold as during glacial intervals. At around MIS 22, climate cooled globally. Gravels, attributed to high-energy braided river systems fed locally by alluvial fans, prograded from the Serio River catchment area over the Leffe Basin and toward the Po Plain in response to a generalized event of vegetation withdrawal and enhanced physical erosion. At this time, Alpine valley glaciers reached their first maximum southward expansion with glacier fronts located at only ∼ 5 km upstream from Leffe.
Two Tales of Municipal Reorganization: Toronto's and Montreal's Diverging Paths Toward Regional Governance and Social Sustainability
Authors: Le Blanc Marie-France
Published: September 2006

Abstract.In Toronto and Montreal, territorial reorganizations modified the arrangements governing regional cooperation, the channels for citizen participation, and the composition of the civic community, all important factors that define the margins local authorities have to control and shape economic and social development. In both cases, these changes brought about a realignment of local civic forces and modified political arrangements at the metropolitan level, leading each city to break from its former path of development.

Résumé.Les réorganisations territoriales de Toronto et Montréal ont modifié les paramètres guidant la coopération régionale, les modes de participation des citoyens et la composition de la communauté civique, soit autant de facteurs déterminant les marges de manœuvre des autorités locales pour encadrer le développement économique et social. Dans les deux cas, ces changements ont modifié les institutions politiques métropolitaines et ont amené les deux villes à s'engager dans de nouvelles avenues.
The Nonindividuation Argument Against Zygotic Personhood
Authors: Guenin Louis
Published: September 2006

I consider the argument, thought to clinch the moral case for use of a human embryo solely as a means, that (i) only a human individual can be a person, (ii) because it can happen at any time before formation of the primitive streak that an embryo splits into monozygotic twins, no embryo in which the primitive streak has not formed is a human individual, and therefore (iii) no embryo in which the primitive streak has not formed is a person. I explore the following proffered arguments for (ii): (a) indivisibility is a necessary condition of individuality, (b) nonidentity of an embryo with successor twins impugns the embryo’s individuality, and (c) totipotency of an embryo’s constituents is inconsistent with the embryo’s being a human individual. These arguments are tested and found wanting; so too is an alternative to (a), the argument that indivisibility is intrinsic to personhood. Whereupon (ii) is unsustained. In search of ways to rehabilitate the nonindividuation argument, I canvass alternative metaphysical views and inquire further into biological individuality, but find that the argument cannot be saved. I conclude by analyzing where this leaves matters concerning the morality of embryo use.
Kantian Duties to the Self, Explained and Defended
Authors: Timmermann Jens
Published: September 2006

The present article is an attempt to clarify the Kantian conception of duties to the self and to defend them against common objections. Kant’s thesis that all duty rests on duties to the self is shown to follow from the autonomy of the human will; and the allegation that they are impossible because the agent could always release himself from such a duty turns out to be question-begging. There is no attempt to prove that there are such duties, but they are revealed to be an indispensable part of morality. Traditional attributes of moral commands, such as ‘categoricity’ or ‘overridingness’ make no sense in a one-sidedly other-regarding or social conception of morality.
The revolt of ‘Abdallāh b. Mu‘āwiya, AH 127–130: a reconsideration through the coinage
Authors: BERNHEIMER TERESA
Published: September 2006

‘Abdallāh b. Mu‘āwiya b. ‘Abdallam h b. Ja‘far b. Abī Tālib, great-grandson of ‘Alī's brother Ja‘far, rose up in Kufa in Muharram of 127/October 744. He was defeated by Umayyad forces in 130 (747–748), and killed by Abū Muslim in Khurāsaān. During the two years of his uprising, Ibn Mu‘āwiya established himself in the Jibāl and Fārs, where he appointed governors, collected taxes and struck his own coins. Ibn Mu‘āwiya's coinage is an important source for the revolt, which is among the most important uprisings of the late Umayyad period. It presents evidence for a strong and unified movement, and corroborates the interpretation of a ‘dress rehearsal’ for the ‘Abbāsid Revolution. This article suggests some alternatives regarding the chronology and geography of Ibn Mu‘āwiya's revolt through a re-examination of textual sources and new coinage, and shows the usefulness of numismatics for the historical study of early Islam.
Survey on the involvement of consumers in health technology assessment programs
Authors: Hailey David , Nordwall Margareta
Published: September 2006

Objectives: The aim of this study was to obtain information from members of the International Network of Agencies for Health Technology Assessment (INAHTA) on their involvement of consumers (patients, carers, and related organizations) in their programs.

Methods: A questionnaire for a survey was developed and sent to member agencies in October 2005.

Results: Of the thirty-seven agencies that provided responses, 57 percent involve consumers in some aspects of their HTA programs and 83 percent intend to involve consumers in the future. Summaries of HTA reports that are intended to be easily understood by consumers are prepared by 49 percent of the agencies, and 36 percent involve consumers in dissemination of HTA material.

Conclusions: Most INAHTA members involve consumers in some aspects of their programs, although not always routinely. Involvement seems likely to increase in the future.
Epicardial Development in the Rat: A New Perspective
Authors: Nesbitt Tresa , Lemley Aubrey , Davis Jeff , Yost Michael J. , Goodwin Richard L. , Potts Jay D.
Published: September 2006

Development of the epicardium is critical to proper heart formation.
It provides all of the precursor cells that form the coronary system and
supplies signals that stimulate cardiac myocyte proliferation. The
epicardium forms from mesothelial cells associated with the septum
transversum and is referred to as the proepicardium (PE). Two different
methods by which these PE cells colonize the developing heart have been
described. In avians, PE cells form a bridge to the heart over which PE
cells migrate onto the heart. In fish and mammals, PE cells form vesicles
of cells that detach from the mesothelium, float through the pericardial
cavity, and attach to the heart. A previous study of rat PE development
investigated this process at the histological level. Protein markers have
been developed since this study. Thus, we investigated this important
developmental process coupled with these new markers using other
visualization techniques such as scanning electron microscopy (SEM) and
confocal microscopy. Finally, a novel, three-dimensional (3-D) culture
system was used to confirm the identity of the PE cells. In this study, we
found convincing evidence that the rat PE cells directly attach to the
heart in a manner similar to that observed in avians.
Helicobacter pylori 2006: Wie testen, wann behandeln
Authors: van der Weg  , Meyenberger  , Borovicka
Published: September 2006

Die Rolle von H.pylori bei der Ulkuskrankheit, dem Magenkarzinom und MALT-Lymphom (Mukosa-assoziiertes lymphatisches Gewebe) ist belegt. Bei der Dyspepsie werden der Wert der H.pylori-Diagnostik und die Eradikationstherapie kontrovers diskutiert. Bei Patienten älter als 45 Jahre wird bei dyspeptischen Beschwerden eine Endoskopie empfohlen. Bei Patienten jünger als 45 Jahre ist eine nichtinvasive Abklärung eine adäquate Option, sofern keine Alarmsymptome vorliegen. Als nichtinvasive Tests haben sich die H.pylori-Serologie, der ଓC-Atemtest und der Stuhl-Antigentest etabliert. Die Therapie von H.pylori besteht aus einem Protonenpumpeninhibitor (PPI) und zwei Antibiotika. Ein Therapieversagen tritt nicht selten auf. Nach zweimaligem Therapieversagen ist eine H.pylori-Kultur zur Bestimmung der Resistenzen indiziert.
Funktionelle Musik zur Therapie essentieller Hypertonie
Authors: Brandes Vera , Maier Wolfgang , Ottowitz Gernot
Published: September 2006

Zusammenfassung. In einer Vielzahl von Studien wurden in den letzten Jahren die Wirkungen von Musik experimentell sowie empirisch untersucht. Dies führte zu einem zunehmenden Interesse der Naturwissenschaften an verschiedenen Formen der Musiktherapie und dem Einsatz von Musik in der Medizin. Trotzdem sind die Wirkungsmechanismen zum größten Teil noch unerforscht. Die hier beschriebene Studie hat es sich zur Aufgabe gesetzt, verschiedene Wirkungsaspekte näher zu ermitteln. Dabei wurde der Einsatz einer speziell entwickelten rezeptiven Musiktherapie bei verschiedenen Krankheitsbildern analysiert, deren Ursachen in hohem Maße psychosomatisch bedingt sind. Dieser Beitrag über den Einsatz von rezeptiver Musiktherapie bei Bluthochdruck erörtert das Studiendesign und setzt einen Schwerpunkt auf die angewandten psychologischen sowie physiologischen Untersuchungs- bzw. Analyseverfahren. Zusätzlich werden erste Zwischenergebnisse, welche vorerst auf den statistischen Auswertungen der mittels Fragebögen erhobenen Daten basieren, präsentiert.
Paleomagnetism of the 1.1 Ga Umkondo large igneous province in southern Africa
Authors: Gose Wulf A. , Hanson Richard E. , Dalziel Ian W. D. , Pancake James A. , Seidel Emily K.
Published: September 2006

The Umkondo dolerites are present over a wide area in the Kalahari craton, southern Africa. Thirty‐nine sampling sites in Botswana and South Africa yielded tightly grouped paleomagnetic directions due south with shallow inclinations and three sites of opposite polarity. The dolerites have U‐Pb single‐crystal baddeleyite or zircon crystallization ages of 1112 ± 0.5 to 1108 ± 0.9 Ma. These results can be combined with published data from 39 additional Umkondo sites and 33 sites in the Grunehogna Province of Antarctica after restoring East Antarctica to its position next to southern Africa. Grouping the sites geographically yields 10 site mean poles with mean at 64.0°N, 38.8°E, A95 = 3.7°. This Umkondo pole can be correlated with Keweenawan poles from Laurentia. Because both sets of poles are precisely of the same age as well as predominantly of one polarity, the relative orientation of the two cratons within the Rodinia supercontinent is fixed. This implies that the Namaqua‐Natal‐Maud belt which rims the southern part of the Kalahari craton, faced away from Laurentia. The Umkondo pole combined with published poles suggest that the Kalahari craton remained distinctly south of the Laurentian craton between 1.1 and 1.0 Ga, making it highly unlikely that the two cratons collided.
Sea ice thickness in the southwestern Sea of Okhotsk revealed by a moored ice‐profiling sonar
Authors: Fukamachi Yasushi , Mizuta Genta , Ohshima Kay I. , Toyota Takenobu , Kimura Noriaki , Wakatsuchi Masaaki
Published: September 2006

Using a moored ice‐profiling sonar along with a moored acoustic Doppler current profiler, a total spatial section of draft across 3334 km of sea ice was obtained in the southwestern Sea of Okhotsk near Hokkaido in the winters of 1999–2001. Using this draft data set, the average draft and keel statistics are discussed in this sea for the first time. The mean draft was 0.60 m, which corresponds to the thickness of 0.71 m, over the three winters with the range of 0.49–0.72 m for each winter. The classification of level and deformed ice reveals a small range of the monthly mean level ice draft (0.18–0.27 m) and the dominance of the deformed ice in terms of volume (80%). The mean draft varied with the areal ratio of the deformed ice fairly well. These results suggest that dynamic processes such as ridging and rafting are important for the evolution of draft in the region of observation. The observed draft probability density distribution and keel statistics show that the thick ice ratio and keel frequency are lower than the similar data in polar regions and closer to those observed in Davis Strait west of Greenland. Along with the ice concentration and speed derived from the satellite data the southward ice transport to the southwestern Sea of Okhotsk is estimated on the basis of the observed sea ice thickness. The estimated ice transport ranged from 15 to 70 km3 in each winter. The heat and freshwater transport associated with the ice transport ranged from −3.9 × 1017 to −1.8 × 1018 J and from 12 to 57 km3, respectively.
Effect of UV scattering on SO2 emission rate measurements
Authors: Mori Takehiko , Mori Toshiya , Kazahaya Kohei , Ohwada Michiko , Hirabayashi Jun'ichi , Yoshikawa Shin
Published: September 2006

We report the quantitative evaluation of the UV scattering effect on the SO2 emission rate measurement by the compact UV spectrometer system. Plume spectra were obtained simultaneously at three measuring points with different distance to the volcanic plume. The apparent absorbance decreases with increasing distance to the plume and the attenuation becomes stronger at shorter wavelength bands. In addition, the attenuation intensity depends on the SO2 column concentration. The underestimation of the measured absorbance caused by the UV scattering leads to the underestimation of the SO2 emission rate. The attenuation was not significant with any wavelength band (<±10%) at 0.6 km but was 35–50% with shorter wavelength band at 2.6 km distance. The UV scattering effect on the SO2 emission rate estimation can be evaluated by the comparison of the emission rates calculated with different wavelength bands.
Summertime tropospheric ozone columns from Aura OMI/MLS measurements versus regional model results over the United States
Authors: Jing P. , Cunnold D. , Choi Y. , Wang Y.
Published: September 2006

Ozone columns below 147 hPa are derived over the United States from September 2004 to August 2005 from the differences between clear‐sky Aura OMI columns and coincident MLS columns. The mean difference from coincident ozonesonde measurements at four USA sites is 0.3 DU with an rms difference of 10.1 DU and a correlation coefficient of 0.67. Semimonthly patterns of the columns over the USA for the summer of 2005 have been produced. The observed columns, as well as Regional Air Quality Forecast (RAQAST) model columns, show high values over the southeastern USA and its surrounding oceans. Changes of these columns exceeding 6 DU in many places were observed between June 17–30 and July 1–16 and the changes reversed in the following two‐week period. Comparisons against calculations from the RAQAST model, as well as correlations with geopotential height changes at 147 hPa, indicate that these changes were primarily related to dynamics.
A simple pan‐evaporation model for analysis of climate simulations: Evaluation over Australia
Authors: Rotstayn Leon D. , Roderick Michael L. , Farquhar Graham D.
Published: September 2006

We show that a simple model of pan evaporation (“PenPan”) can be used to analyze monthly mean output from a global climate model (GCM). PenPan is based on a modified version of Penman's potential evapotranspiration equation. Very good agreement is obtained with observed annual pan evaporation for Australian sites when PenPan is forced by surface observations of radiation, wind speed, humidity and air temperature. When PenPan is forced with monthly mean output from the CSIRO GCM, the results are still satisfactory, but pan evaporation is overestimated over southern Australia, primarily due to excessive surface solar radiation simulated by the GCM. The results suggest that PenPan will be a valuable tool for reconciling observed pan‐evaporation trends with climate‐model simulations.
Tomographic evidence for the Eurasian lithosphere subducting beneath south Taiwan
Authors: Wang Zhi , Zhao Dapeng , Wang Jian , Kao Honn
Published: September 2006

A tomographic image of the crust and upper mantle beneath the Taiwan Island as derived from local, regional and teleseismic data simultaneously revealed a high‐velocity zone from the surface down to a depth of 300 km, locating beneath south Taiwan (to the south of latitude 24°N). We interpret this high‐velocity zone to be the subducted Eurasian lithosphere. Our result is different from a global tomography study that shows the Eurasian plate subducting beneath most part of the Taiwan Island down to 670 km depth. This down‐going model of the Eurasian lithosphere implies that the tectonic framework of Taiwan has been changing from subduction in the south to collision in the north, which provides geophysical evidence supporting the previous proposed models. The subducted Eurasian lithosphere colliding with the subducted Philippine Sea plate would have contributed to the mountain building, active seismicity and crustal deformation in the study region due to the lower part of the Eurasian continental plate subducted beneath south Taiwan.
Coastline responses to changing storm patterns
Authors: Slott Jordan M. , Murray A. Brad , Ashton Andrew D. , Crowley Thomas J.
Published: September 2006

Researchers and coastal managers are pondering how accelerated sea‐level rise and possibly intensified storms will affect shorelines. These issues are most often investigated in a cross‐shore profile framework, fostering the implicit assumption that coastline responses will be approximately uniform in the alongshore direction. However, experiments with a recently developed numerical model of coastline change on a large spatial domain suggest that the shoreline responses to climate change could be highly variable. As storm and wave climates change, large‐scale coastline shapes are likely to shift—causing areas of greatly accelerated coastal erosion to alternate with areas of considerable shoreline accretion. On complex‐shaped coastlines, including cuspate‐cape and spit coastlines, the alongshore variation in shoreline retreat rates could be an order of magnitude higher than the baseline retreat rate expected from sea‐level rise alone.
Tracking control and synchronization of four-dimensional hyperchaotic Rössler system
Authors: Wang Xing-Yuan , Wu Xiang-Jun
Published: September 2006

In this paper we study the problem of the four-dimensional hyperchaotic Rössler system tracking control. A controller based on the reference signal is designed. It is theoretically proved that the controller can make the error converge to zero exponentially. Numerical results have verified the validity of the controller. The Rössler system cannot only track any reference signal fast, but can synchronize with identical or different chaotic systems.
Experimental study of the transitions between synchronous chaos and a periodic rotating wave
Authors: Sánchez Esteban , Pazó Diego , Matías Manuel A.
Published: September 2006

In this work we characterize experimentally the transition between periodic rotating waves and synchronized chaos in a ring of unidirectionally coupled Lorenz oscillators by means of electronic circuits. The study is complemented by numerical and theoretical analysis, and the intermediate states and their transitions are identified. The route linking periodic behavior with synchronous chaos involves quasiperiodic behavior and a type of high-dimensional chaos known as chaotic rotating wave. The high-dimensional chaotic behavior is characterized, and is shown to be composed actually by three different behaviors. The experimental study confirms the robustness of this route.
Determination of chiral asymmetries in the valence photoionization of camphor enantiomers by photoelectron imaging using tunable circularly polarized light
Authors: Nahon Laurent , Garcia Gustavo A. , Harding Chris J. , Mikajlo Elisabeth , Powis Ivan
Published: September 2006

An electron imaging technique has been used to study the full angular distribution of valence photoelectrons produced from enantiomerically pure molecular beams of camphor when these are photoionized with circularly polarized light. In addition to the familiar β parameter, this provides a new chiral term, taking the form of an additional cosine function in the angular distribution which consequently displays a forward-backward electron ejection asymmetry. Several ionization channels have been studied using synchrotron radiation in the 8.85–26eV photon energy range. With alternating left and right circularly polarized radiations the photoelectron circular dichroism (PECD) in the angular distribution can be measured and shows some strong dynamical variations with the photon energy, depending in sign and intensity on the ionized orbital. For all orbitals the measured PECD has a quite perfect antisymmetry when switching between R and S enantiomers, as expected from theory. In the HOMO−1 channel the PECD chiral asymmetry curves show a double maxima reaching nearly 10% close to threshold, and peaking again at ∼20% some 11eV above threshold. This is attributed to a resonance that is also visible in the β parameter curve. Newly optimized CMS-Xα photoionization dynamics calculations are also presented. They are in reasonably good agreement with the experimental data, including in the very challenging threshold regions. These calculations show that PECD in such randomly oriented samples can be understood in the electric dipole approximation and that, unlike the case pertaining in core-shell ionization—where a highly localized achiral initial orbital means that the dichroism arises purely as a final state scattering effect—in valence shell ionization there is a significant additional influence contributed by the initial orbital density.
A general multiscroll Lorenz system family and its realization via digital signal processors
Authors: Yu Simin , Lü Jinhu , Tang Wallace K. S. , Chen Guanrong
Published: September 2006

This paper proposes a general multiscroll Lorenz system family by introducing a novel parameterized nth-order polynomial transformation. Some basic dynamical behaviors of this general multiscroll Lorenz system family are then investigated, including bifurcations, maximum Lyapunov exponents, and parameters regions. Furthermore, the general multiscroll Lorenz attractors are physically verified by using digital signal processors.
Design and implementation of a flux compression generator nonexplosive test bed for electroexplosive fuses
Authors: Belt D. , Mankowski J. , Neuber A. , Dickens J. , Kristiansen M.
Published: September 2006

Helical flux compression generators (HFCGs) of a 50mm form factor have been shown to produce output energies on the order of ten times the seeded value and a typical deposited energy of 3kJ into a 3μH inductor. By utilizing an electroexplosive fuse, a large dI∕dt into a coupled load is possible. Our previous work with a nonoptimized fuse has produced ∼100kV into a 15Ω load, which leads into a regime relevant for high power microwave systems. It is expected that ∼300kV can be achieved with the present two-stage HFCG driving an inductive storage system with electroexploding fuse. In order to optimize the electroexplosive wire fuse, we have constructed a nonexplosive test bed which simulates the HFCG output with high accuracy. We have designed and implemented a capacitor based, magnetic switching scheme to generate the near exponential rise of the HFCG. The varying inductance approach utilizes four stages of inductance change and is based upon a piecewise linear regression model of the HFCG wave form. The nonexplosive test bed will provide a more efficient method of component testing and has demonstrated positive initial fuse results. By utilizing the nonexplosive test bed, we hope to reduce the physical size of the inductive energy storage system and fuse substantially.
Unbinding of the streptavidin-biotin complex by atomic force microscopy: A hybrid simulation study
Authors: Zhou Jian , Zhang Luzheng , Leng Yongsheng , Tsao Heng-Kwong , Sheng Yu-Jane , Jiang Shaoyi
Published: September 2006

A hybrid molecular simulation technique, which combines molecular dynamics and continuum mechanics, was used to study the single-molecule unbinding force of a streptavidin-biotin complex. The hybrid method enables atomistic simulations of unbinding events at the millisecond time scale of atomic force microscopy (AFM) experiments. The logarithmic relationship between the unbinding force of the streptavidin-biotin complex and the loading rate (the product of cantilever spring constant and pulling velocity) in AFM experiments was confirmed by hybrid simulations. The unbinding forces, cantilever and tip positions, locations of energy barriers, and unbinding pathway were analyzed. Hybrid simulation results from this work not only interpret unbinding AFM experiments but also provide detailed molecular information not available in AFM experiments.
Two-dimensional chiral model for liquid crystals, bent hard needles: A Monte Carlo simulation
Authors: Peón Jorge , Saucedo-Zugazagoitia Jimena , Pucheta-Mendez Fabian , Perusquía Raúl A. , Sutmann Godehard , Quintana-H Jacqueline
Published: September 2006

The liquid crystalline behavior of a two dimensional (2D) model of hard needles bent into a “zigzag shape” is studied. This model, originally designed to study two dimensional chiral segregation, also shows liquid crystalline behavior and has some anomalous features which are contrasted in relation to the following: (i) Most of the microscopical models used to study liquid crystals have a symmetry axis that coincides with a molecular axis; (ii) in three-dimensions, chiral molecules can form cholesteric instead of nematic phases; (iii) the smectic phase is usually found when attractions are present or at least when the molecules have finite volume. Despite the fact that the present 2D model does not have any of these characteristics, numerical evidence is found for the occurrence of nematic and smectic phases. Since these molecules are athermal, infinitely repulsive, and infinitesimally thin, the liquid crystalline characteristics are attributed to excluded volume effects. To determine the mesophases of the model, both nematic and smectic order parameters as well as distribution functions are computed.
Photoinduced fluorescence intensity oscillation in a reaction-diffusion cell containing a colloidal quantum dot dispersion
Authors: Komoto Atsushi , Maenosono Shinya
Published: September 2006

The nonlinear spontaneous oscillation of photoluminescence (PL) intensity in an ensemble of semiconductor quantum dots (QDs), which differs from the fluorescence intermittency of a single QD, is investigated. The PL intensity in a QD dispersion slowly oscillates with time under continuous illumination. The oscillatory behavior is found to vary with changing QD concentration, solvent viscosity, volume fraction of irradiated region, and irradiation intensity. On the basis of the Gray-Scott model [Chemical Oscillation and Instabilities: Non-linear Chemical Kinetics (Clarendon, Oxford, 1994); J. Phys. Chem. 89, 22 (1985); Chem. Eng. Sci. 42, 307 (1987)], and its comparison with the experimental results, it is revealed that the following processes are important for PL oscillation: (1) mass transfer of QDs between the illuminated and dark regions, (2) autocatalytic formation of vacant sites on QD surfaces via photodesorption of ligand molecules, and (3) passivation of vacant sites via photoadsorption of water molecules.
Galois quantum systems, irreducible polynomials and Riemann surfaces
Authors: Vourdas A.
Published: September 2006

Finite quantum systems in which the position and momentum take values in the Galois field GF(pℓ), are studied. Ideas from the subject of field extension are transferred in the context of quantum mechanics. The Frobenius automorphisms in Galois fields lead naturally to the “Frobenius formalism” in a quantum context. The Hilbert space splits into “Frobenius subspaces” which are labeled with the irreducible polynomials associated with the ypℓ−y. The Frobenius maps transform unitarily the states of a Galois quantum system and leave fixed all states in some of its Galois subsystems (where the position and momentum take values in subfields of GF(pℓ)). An analytic representation of these systems in the ℓ-sheeted complex plane shows deeper links between Galois theory and Riemann surfaces.
Simulation of the gyroid phase in off-lattice models of pure diblock copolymer melts
Authors: Martínez-Veracoechea Francisco J. , Escobedo Fernando A.
Published: September 2006

Particle-based molecular simulations of pure diblock copolymer (DBC) systems were performed in continuum space via dissipative particle dynamics and Monte Carlo methods for a bead-spring chain model. This model consisted of chains of soft repulsive particles often used with dissipative particle dynamics. The gyroid phase was successfully simulated in DBC melts at selected conditions provided that the simulation box size was commensurate with the gyroid lattice spacing. Simulations were concentrated at conditions where the gyroid phase is expected to be stable which allowed us to outline approximate phase boundaries. When more than one phase was observed by varying simulation box size, thermodynamic stability was discerned by comparing the Helmholtz free energy of the competing phases. For this purpose, chemical potentials were efficiently simulated via an expanded ensemble that gradually inserts/deletes a target chain to/from the system. These simulations employed a novel combination of Bennett’s [J. Comput. Phys. 22, 245 (1976)] acceptance-ratio method to estimate free-energy differences and a recently proposed method to get biasing weights that maximize the number of times that the target chain is regrown. The analysis of the gyroid nodes revealed clear evidence of packing frustration in the form of an (entropically) unfavorably overstretching of chains, a phenomenon that has been suggested to provide the structural basis for the limited region of stability of the gyroid phase in the DBC phase diagram. Finally, the G phase and nodal chain stretching were also found in simulations with a completely different DBC particle-based model.
Determination of the nonlinear dielectric increment in the Cole-Davidson model
Authors: Déjardin Jean-Louis , Jadzyn Jan
Published: September 2006

The problem of the nonlinear dielectric relaxation of complex liquids is tackled in the context of the Cole-Davidson [J. Chem. Phys. 19, 1484 (1951)] model. By using an appropriate time derivative of noninteger order, an infinite hierarchy of differential-recurrence relations for the moments (expectation values of the Legendre polynomials) is obtained. The solution is established for the stationary regime of an ensemble of polar and symmetric-top molecules acted on by a strong dc bias electric field superimposed on a weak ac electric field. The results for the first three nonlinear harmonic components of the electric susceptibility are analytically established and illustrated with the help of Argand diagrams for the nonlinear dielectric increment and three-dimensional dispersion and absorption spectra for the second and the third harmonic components as a function of the anomalous exponent β⩽1, the value of which gives rise to skewed arcs (Argand plots) and asymmetric shapes (loss spectra) in the high-frequency domain.
Observation of step-induced magnetic domain formation in La1−xSrxMnO3 thin films by photoelectron emission microscopy
Authors: Taniuchi T. , Kumigashira H. , Oshima M. , Wakita T. , Yokoya T. , Kubota M. , Ono K. , Akinaga H. , Lippmaa M. , Kawasaki M. , Koinuma H.
Published: September 2006

Magnetic domain formation in thin films of La1−xSrxMnO3 (LSMO) with x=0.2 and 0.4 epitaxially grown on stepped SrTiO3 (001) substrates has been investigated by photoelectron emission microscopy. The magnetic domains show a stripe structure elongated along the step directions, indicating uniaxial magnetic anisotropy induced by step structures. We have also found that the magnetization of the magnetic domains is slightly meandering at domain boundaries. The existence of the additional structures suggests that the magnetic domains in LSMO films are also influenced by biaxial magnetocrystalline anisotropy. The direct observation of the magnetic domain structures suggests that the competition between the two magnetic anisotropies may play an important role in magnetic properties in LSMO films.
Interface modification of a pentacene field-effect transistor with a submicron channel
Authors: Tsukagoshi K. , Shigeto K. , Yagi I. , Aoyagi Y.
Published: September 2006

Effective interface modification of a pentacene field-effect transistor with a submicron channel is performed. The two interfaces between the pentacene channel and the substrate and between the channel and the metallic electrode are markedly changed by nanoscale modification. At the substrate interface, thin polyparaxylylene film was formed, resulting in higher field-effect mobility of the short-channel transistor. A further increase in the field-effect mobility is achieved when multiple layers of tetracyanoquinodimethane are introduced to the pentacene film beneath the metallic electrodes.
Effect of interfacial strain on the morphological instability of noncommon anion semiconductor epitaxial films
Authors: Li J. H. , Stokes D. W.
Published: September 2006

A simple thermodynamic approach has been employed to study the effect of interfacial strain, arising from distinct interfacial bonding, on the morphological instability of some noncommon anion semiconductor epitaxial films. The authors have particularly considered a case in which the interfacial strain is significantly greater than the strain in the film. The authors show that it is possible for a lightly strained film to transit from two-dimensional growth to three-dimensional growth at a significantly reduced thickness if the small film strain is of the same sign as the large interfacial strain.
Characterization of InN layers grown by high-pressure chemical vapor deposition
Authors: Alevli M. , Durkaya G. , Weerasekara A. , Perera A. G. U. , Dietz N. , Fenwick W. , Woods V. , Ferguson I.
Published: September 2006

Structural and optical properties of indium nitride (InN) layers grown by high-pressure chemical vapor deposition (HPCVD) on sapphire and GaN epilayers have been studied. HPCVD extends processing parameters beyond those accessible by molecular beam epitaxy and metal organic chemical vapor deposition, enabling the growth of epitaxial InN layers at temperatures as high as 1150K for reactor pressures around 15bars, leading to vastly improved material properties. InN layers grown on GaN(0002) epilayers exhibit single-phase InN(0002) x-ray diffraction peaks with full width at half maximum (FWHM) around 430arcsec. Optical characterization of the InN layers by infrared (IR) reflectance reveals free carrier concentrations in the low to mid-10+19-cm−3 and optical dielectric function ε∞=5.8. The optical properties in the visible and near IR spectral ranges were analyzed by transmission spectroscopy, showing an absorption edge around 1.5eV. The shift of the absorption edge correlates with deviations in the InN stoichiometry, indicating that the understanding and control of the point defect chemistry of InN is critical for improved material properties.
CsBr photocathode at 257nm: A rugged high current density electron source
Authors: Liu Zhi , Maldonado Juan , Sun Yun , Pianetta Piero , Pease R. F. W.
Published: September 2006

There is a continuing need for high intensity electron sources that will operate in demountable vacuum and can be externally modulated. Materials with wide band gap, e.g., diamond, are rugged but need photon energies exceeding the band gap to emit efficiently and this rules out the use of cw lasers. The authors have found that a photocathode of CsBr is both adequately intense (>150A∕cm2) and rugged and can be excited with photons of energy of 4.8eV (257nm). This is below the energy gap of CsBr (7.3eV) but such operation can be explained by the presence of intraband states about 4eV below the conduction band minimum.
Submillisecond response of a photorefractive polymer under single nanosecond pulse exposure
Authors: Eralp M. , Thomas J. , Tay S. , Li G. , Schülzgen A. , Norwood R. A. , Yamamoto M. , Peyghambarian N.
Published: September 2006

Individual nanosecond pulses at 532nm are applied to record gratings in photorefractive composite. At 4mJ∕cm2 illumination, maximum diffraction efficiencies of 56% have been reached with a build-up time of only 300μs (t1) demonstrating one order of magnitude faster recording compared to writing with continuous wave beams. This fast response enables applications in optical processing requiring frame rates of 100Hz or more. Due to the short duration of the writing pulses, the recording is insensitive to vibrations.
Compact Mach-Zehnder acousto-optic modulator
Authors: de Lima M. M. , Beck M. , Hey R. , Santos P. V.
Published: September 2006

The authors demonstrate a compact optical waveguide modulator based on a Mach-Zehnder interferometer driven by surface acoustic waves. The modulator was monolithically fabricated on GaAs with an active region length of approximately 15μm. It yields peak-to-peak modulation exceeding 90% of the average transmission and operation in the gigahertz frequency range.