bluuebunny/crossref_metadata_2025 huggingface dataset:
Ternary Alkali Metal Transition Metal Acetylides
Authors: Ruschewitz Uwe
Published: March 2006

The first alkali metal transition metal acetylides of general composition A2M0C2 (A = Na − Cs, M0 = Pd, Pt) were obtained by solid state reactions of alkali metal acetylides with palladium and platinum. They are characterized by $^{1}_{\infty}[{\rm M}^{\rm o}({\rm C}_{2})^{2-}_{{2}/{2}}]$ chains, which are separated by alkali metal ions. Analogous $^{1}_{\infty}[{\rm M}^{\rm o}({\rm C}_{2})^{2-}_{{2}/{2}}]$ chains also separated by alkali metal ions are the characteristic structural feature of acetylides of composition AMIC2, which are accessible by reacting AC2H with MII in liquid ammonia (A = Li − Cs, MI = Cu, Ag, Au). Despite their structural similarities they possess different properties, as acetylides of composition A2M0C2 are semiconductors with very small indirect band gaps and slightly extended C–C distances compared to a C–C triple bond, whereas acetylides of composition AMIC2 show a typical salt‐like behavior with C–C distances close to the expected value for a C–C triple bond of 120 pm. But with the help of simple chemical models these differences can be made plausible. Furthermore, it is shown that only by a combination of different methods (powder diffraction with X‐rays and neutrons, solid state NMR spectroscopy, Raman spectroscopy) it was possible to characterize this new class of compounds structurally and chemically.
Septal anterior ventricular exclusion operation (Pacopexy) for ischemic dilated cardiomyopathy: treat form not disease
Authors: Isomura Tadashi , Horii Taiko , Suma Hisayoshi , Buckberg Gerald D. ,   the RESTORE Group
Published: March 2006

Objective: Restoration of left ventricle size and shape is an effective surgical procedure in patients with dilated cardiomyopathy. This report defines early and intermediate results following the reshaping of the left ventricle from spherical to ellipsoid configuration in patients with ischemic cardiomyopathy, employing a technique for LV restoration (LVR) that uses form rather than disease as the endpoint for oblique patch placement. Methods: Between 1998 and 2004, a cohort of 83 patients with dilated ischemic cardiomyopathy underwent an operation to reshape the left ventricle. In 54 patients the Dor procedure was done, and 29 underwent the septal anterior ventricular exclusion (SAVE) procedure to emphasize the elliptical shape, whereby patch placement followed an oblique trajectory between the LV apex and septum below the aortic valve. Ventricular form, rather than the disease scar marked the suture placement site endpoint to create an ellipse. The mean age was 58 ± 27, but SAVE patients had larger end systolic volume index (135 ± 38 vs 95 ± 25*). Overall preoperative NYHA functional class III was in 69% and IV in 31 patients, but more SAVE patients were in class IV (38% vs 28%*). The procedures were elective in 72 and emergent in 11, with similar entry criteria for each procedure. Results: In combination with LVR operation, mitral surgery was performed in 49/83 and tricuspid annuloplasty in 23/83 patients, but these procedures were more common after SAVE (59% vs 44%* and 45% vs 19%*, respectively), because of larger LV volumes in SAVE patients; 2.8 ± 1.3 coronary artery bypass grafts were used. Perioperative use of IABP or LVAD was 15 and 1, respectively in 83 patients. Hospital death was in 1/11 or 9% after emergent operations and 3/72 or 4% in elective procedures, with no difference between groups. After discharge from the hospital, NYHA class improved to class I or II in 57 patients, class III/IV in 14 patients, with 10 late deaths. The 5-year survival rate after the elective operation was 80.3% in SAVE and with elective operation and 77.4% in the Dor procedure. Conclusion: The SAVE or Pacopexy technique is easy to reshape the dilated left ventricle from spherical to ellipsoid form after the LVR, and the resultant improved configuration may contribute to the overall results for patients with ischemic dilated cardiomyopathy.
The Ballad of Bourg-Madame: Memory, Exile, and the Spanish Republican Refugees of the Retirada of 1939
Authors: Gemie Sharif
Published: March 2006

This paper analyses the experience of the Spanish Republican refugees who left Catalonia in the Retirada of January and February 1939. The first section – “the Road to Bourg-Madame” – considers issues of interpretation raised by the refugees' texts: it discusses historiography, the politics of memory, and political culture. In “Bourg-Madame”, the second section, the essay considers the refugees' experiences. It discusses previous patterns of Spanish migration, the decision-making process that preceded the refugees' journey, group identity formation during the Retirada, the gendered dimension of their experiences, the despair felt by many on arrival in France and the reception that the refugees met. The paper ends by discussing the surprising resilience of the refugees.
Managing Police Constables and Firefighters: Uniformed Public Services in English Cities, c.1870–1930
Authors: Ewen Shane
Published: March 2006

Using a variety of archival sources, notably personnel records and municipal minute books, this article builds a picture of the work-life histories of rank-and-file police constables and firefighters in the English cities of Birmingham and Leicester, and contrasts the techniques of behavioural control adopted by their employers. By drawing on an expanding literature on the social history of public institutions, the article compares the experience of managing such disciplined and uniformed public services. The article demonstrates that municipal management combined insidious devices for controlling workers' behaviour with consensual and negotiated tactics deployed by workers aware of the tangible material benefits offered by a career in public service. Moreover, by placing the English experience of municipal policing and fire-fighting in an international context by focusing on the visits and writings made by prominent technical and social reformers, the article offers a framework within which comparative research can be undertaken.
The Common Soldier in Rebel Armies: An Introduction
Authors: Hart Marjolein 't
Published: March 2006

With the following two contributions the International Review of Social History hopes to focus scholarly attention on a rather neglected theme: the labour conditions of the ordinary foot soldiers in rebel armed forces. Although quite disparate in time, social setting, and method, both articles deal with the position and circumstances of common soldiers; both study these soldiers during a period of civil war; and both deal with rebel forces that were ultimately to emerge victorious and eventually be transformed into a regular army. Erik Swart's contribution on the soldiers in the army of the northern Netherlands is set in the late sixteenth century, just after the start of Holland's war of independence. Within a couple of years, the military underwent a comprehensive process of professionalization. The consequences for ordinary soldiers were far reaching: lower wages, fewer privileges, fewer rights, and an obligation to carry out digging work and other forms of manual labour. By contrast, their predecessors (the Landsknechts) had enjoyed a significantly higher status, with a system of organization not much different from that of nineteenth-century trade unions.
Early PCR detection of tyramine-producing bacteria during cheese production
Authors: Fernández María , Belén Flórez Ana , Linares Daniel M , Mayo Baltasar , Alvarez Miguel A
Published: March 2006

Biogenic amines (BA) are toxic substances that appear in foods and beverages. Tyramine is the most abundant BA in cheeses. A PCR method was developed to detect the presence of tyramine-producing bacteria during cheese manufacture and ripening. Six different batches of a farmhouse blue cheese were analysed by PCR. Tyramine concentrations were also determined by HPLC. The PCR method was able to anticipate tyramine accumulation in the cheeses; the presence of tyramine-producing microorganisms in the early stages of manufacture correlated well with a high concentration of BA in mature cheese samples.
William Perkins as Apologist for the Church of England
Authors: PATTERSON W. B.
Published: March 2006

William Perkins, usually described as an Elizabethan Puritan, was significant in ways that are only beginning to be recognised by historians. His writings, published in numerous editions in England and on the continent and translated into Latin and half a dozen vernacular languages, made him the most prominent English theologian of his day. This article contends that his career was devoted not to bringing about changes in the Established Church but to making that Church's teachings better known and appreciated. Perkins should be seen as a leading apologist for the Elizabethan Church of England.
Gerardo Segarelli as the Anti-Francis: Mendicant Rivalry and Heresy in Medieval Italy, 1260–1300
Authors: CARNIELLO BRIAN R.
Published: March 2006

Scholars generally associate the Order of Apostles, founded around 1260 by Gerardo Segarelli in Parma, Italy, with medieval heresies. This article analyses the leading source for the first three decades of the Apostles, the chronicle of the Franciscan Salimbene de Adam of Parma, and casts Segarelli and the Apostle friars instead as thirteenth-century mendicants who rivalled the Franciscans in the Emilia, the Romagna and the March of Ancona. Salimbene's depiction of Gerardo Segarelli focuses on the chronicler's desire to recreate his rival as an inversion of Francis of Assisi and Franciscan ideals. Gerardo Segarelli emerges in the account as an anti-Francis. Yet only after 1274, when the Second Council of Lyons ordered a general suppression of all religious movements founded after Fourth Lateran in 1215, did the situation change slowly for Segarelli's followers as opponents began to question their obedience to papal authority. Gerardo Segarelli and the Apostle friars ultimately faced condemnation as heretics, but not before the 1290s. Salimbene's chronicle, written in the 1280s, should not be taken as a source for a ‘Segarellian heresy’ launched by a ‘heresiarch’ in the Joachite year 1260, but as a source for mendicant rivalry in the thirteenth century that was deeply passionate in its rhetoric and invective.
Tracking Einhard's ‘Life of Charlemagne’ Einharts Vita Karoli. Studien zur Entstehung, Überlieferung und Rezeption. 2 vols. By Matthias M. Tischler. (Monumenta Germaniae Historica, Schriften, 48.) Pp. lxx+896+8 plates; vii+898–1828. Hanover: Hahnsche Buchhandlung, 2001. €140. 3 7752 5448 X; 0080 6951
Authors: NELSON JANET L.
Published: March 2006

‘Habent sua fata libelli’. Had Einhard been able to contemplate the fate of his own libellus of 41 pages (in the standard modern edition) as revealed in Matthias Tischler's 1,828-page two-volume liber, the gamut of his responses from angst to wonderment would surely have included gratitude. In all the voluminous historiography on the Vita Karoli, no one has paid Einhard the compliment of taking his little book as seriously as has Tischler in bringing this Heidelberg doctoral thesis of 1998, now in expanded form, to a wider audience. The subtitle indicates the three dimensions of Tischler's vast enquiry: the immediate context of the VK's original writing, as Einhard responded creatively to an urgent political situation; the VK's own evolving life (if books have fates, Tischler says they also have lives) through preservation and transmission in an extraordinary number of manuscripts; and the VK's afterlife in its variegated reception across eight centuries by scribes, scholars and patrons. Tischler has taken his cue from the literary historian Paul Aebischer: ‘la Vita Karoli est un immense continent’. In Tischler, the improbable continent – vaster than ever realised before and with larger prospects of cultural riches – has found its hinterland explorer and topographer.
Decline of the Tibetan gazelle Procapra picticaudata in Ladakh, India
Authors: Bhatnagar Yash Veer , Wangchuk Rinchen , Mishra Charudutt
Published: March 2006

The Tibetan gazelle Procapra picticaudata is endemic to the Tibetan plateau. In the Ladakh region of northern India its range declined from c. 20,000 km2 in the early 1900s to c. 1,000 km2 in the late 1980s. Here we report the results of our recent (1999–2003) assessments of the gazelle's conservation status in Ladakh. Range-wide surveys indicate that the present population of the Tibetan gazelle in Ladakh is c. 50, restricted to a range of c. 100 km2. Populations in the Tso Kar basin and Dungti have gone extinct within the past decade. Throughout the last century hunting was the primary cause of the gazelle's decline. Although hunting has been brought under control in the last two decades, intensified livestock grazing appears to have prevented the gazelle's recovery and may be precipitating further declines. The species needs immediate, participatory conservation management, as well as a reassessment of its IUCN Red List status.
Antigemination, assimilation and the determination of identity
Authors: Baković Eric
Published: March 2006

Avoidance of adjacent consonants that are ‘sufficiently identical’ – that is, identical except for possible differences in a small subset of specific features – is argued to result from joint satisfaction of a constraint against geminates (identical adjacent consonants) and other active constraints that independently require assimilation with respect to those features ignored in the determination of identity. The crux of the proposal is the dependence of antigemination on independent assimilation processes, a prediction that is independently verified in case studies from English and Lithuanian. The factorial typology of constraints at the core of the proposal is demonstrated to closely fit a significant range of observed cases.
Saturation of parameter settings in Spanish stress
Authors: Roca Iggy
Published: March 2006

This paper advances a novel analysis of Spanish non-verb stress couched in the metrical model of Halle & Idsardi (1995), minimally augmented with an Edge Marking domain parameter. All relevant data are surveyed, and the patterns are classified on empirical grounds into unmarked, marked and supermarked. The unmarked pattern, assigned by default, has the stem-final syllable stressed, while the marked pattern involves a binary trochee, also on the right edge of the stem, and supermarked stress a non-final binary trochee or a word Edge Marking domain. All and only these patterns are generated, in both singulars and plurals, through permutations in the settings of three of the four Edge Marking components (domain included), checked by an avoidance constraint barring stress from the desinence. The ‘three-syllable window’ directly falls out from this machinery, both in the established Spanish vocabulary and in incoming borrowings, blind mimicry of the source form thus being obviated, indeed contradicted.
Quantity, stress and reduplication in Washo
Authors: Yu Alan C. L.
Published: March 2006

Plural internal reduplication in Washo has generated much interest in the phonological literature. This study presents a novel analysis that unifies the treatment of a set of seemingly disparate aspects of this plural reduplication pattern (e.g. variation in the placement and size of the reduplicant, contrastive vowel length in stressed syllables, post-tonic gemination, and vowel-length inheritance in reduplication), relying on the interaction between constraints on weight assignment, affix anchoring and stress assignment. In particular, the odd placement of the plural reduplicant in roots with internal consonant sequences and the restricted distribution of long vowels in Washo can be attributed to a previously unnoticed emerging preference for heavy stressed syllables on the surface. The results of this study have implications for theories of reduplication and theories of weight phenomena in general.
Risk, modernity and history
Authors: Hasson Ezra
Published: March 2006

A current trend in sociology characterises the end of the twentieth century as obsessed with risk. Ulrich Beck and Anthony Giddens are perhaps the leading expositors of this theme. Both emphasise a break with the past as the last millennium approached its conclusion, whereby changes in patterns of work, technological developments and the demise of traditional social forms have ushered in a new modernity. In their view, social organisations became more reflexive in their assessments of the circumstances of daily life, at a time when new technologies created the possibility of damage on a global scale. The result in the new social world is a society focused on risk. Some aspects of this assessment are uncontroversial. New technologies have emerged, whilst the role of the nation state has changed since its apogee in the nineteenth century. Other aspects of this new vision are, however, empirically more problematic. Furthermore, the degree to which social changes actually had the effects identified by Beck and Giddens remains an open question. Using the early twentieth-century regulation of mental defectives as a case study, this paper will interrogate this ‘discontinuist’ vision, exploring whether and how our understanding of risk has changed.
Adolescence, autonomy and Harry Potter: the child as decision-maker
Authors: Van Praagh Shauna
Published: March 2006

Like all babies, Harry Potter was born vulnerable. Like most babies, he was cared for and loved by those closest to him. When Harry was still an infant, however, the most horrible thing imaginable happened. His parents were killed by Voldemort; in turn, the evil wizard turned his murderous wrath on baby Harry. But Harry was too strong for Voldemort. Without realising it, he destroyed Voldemort’s powers and survived with only a jagged scar on his forehead. Harry Potter may have been vulnerable. But he was also capable of directing the history of the entire wizard world.
A critique of contractual relationships in the aerospace industry: collaboration v conflict
Authors: Cullen Penny-Anne , Butcher Bob , Hickman Richard , Keast John
Published: March 2006

This paper draws on an analysis of case studies from the line of research that examines contractual and working relationships in the aerospace industry (Cullen, Keast and Simpson, 2002; Cullen, Hickman, 2001; Cullen, 2005). These studies found a divergence between the parties’ intended working relationship and the agenda prescribed by formal contracts. The paper proposes that the ramifications of the contractual arrangements engender strains between the dynamic nature of collaborative transactions and the laissez-faire presumption of conflictual relations that underpins western commercial contract law, which in turn influences contractual relations and formal agreements.
Atomic scale control of single molecule charging
Authors: Mikaelian G. , Ogawa N. , Tu X. W. , Ho W.
Published: March 2006

A scanning tunneling microscope was used to study charging of single copper phthalocyanine molecules adsorbed on an ultrathin Al2O3 film grown on a NiAl(110) surface. A double-barrier tunnel junction is formed by a vacuum barrier between the tip and the molecule and an oxide barrier between the molecule and the NiAl. In this geometry the molecule can be charged by the tunneling electrons. This charging was found to be strongly dependent on the position of the tip above the molecule and the applied bias voltage.
Order-parameter-based Monte Carlo simulation of crystallization
Authors: Chopra Manan , Müller Marcus , de Pablo J. J.
Published: March 2006

A Monte Carlo simulation method is presented for simulation of phase transitions, with emphasis on the study of crystallization. The method relies on a random walk in order parameter Φ(qN) space to calculate a free energy profile between the two coexisting phases. The energy and volume data generated over the course of the simulation are subsequently reweighed to identify the precise conditions for phase coexistence. The usefulness of the method is demonstrated in the context of crystallization of a purely repulsive Lennard-Jones system. A systematic analysis of precritical and critical nuclei as a function of supercooling reveals a gradual change from a bcc to a fcc structure inside the crystalline nucleus as it grows at large degrees of supercooling. The method is generally applicable and is expected to find applications in systems for which two or more coexisting phases can be distinguished through one or more order parameters.
Evidence of photon acceleration by laser wake fields
Authors: Murphy C. D. , Trines R. , Vieira J. , Reitsma A. J. W. , Bingham R. , Collier J. L. , Divall E. J. , Foster P. S. , Hooker C. J. , Langley A. J. , Norreys P. A. , Fonseca R. A. , Fiuza F. , Silva L. O. , Mendonça J. T. , Mori W. B. , Gallacher J. G. , Viskup R. , Jaroszynski D. A. , Mangles S. P. D. , Thomas A. G. R. , Krushelnick K. , Najmudin Z.
Published: March 2006

Photon acceleration is the phenomenon whereby a light wave changes color when propagating through a medium whose index of refraction changes in time. This concept can be used to describe the spectral changes experienced by electromagnetic waves when they propagate in spatially and temporally varying plasmas. In this paper the detection of a large-amplitude laser-driven wake field is reported for the first time, demonstrating photon acceleration. Several features characteristic of photon acceleration in wake fields, such as splitting of the main spectral peak and asymmetries between the blueshift and redshift for large shifts, have been observed. The experiment is modeled using both a novel photon-kinetic code and a three-dimensional particle-in-cell code. In addition to the wide-ranging applications in the field of compact particle accelerators, the concept of wave kinetics can be applied to understanding phenomena in nonlinear optics, space physics, and fusion energy research.
Component-resolved determination of the magnetization by magnetization-induced optical second-harmonic generation
Authors: Gerrits Th. , Silva T. J. , Rasing Th.
Published: March 2006

We present a method for simultaneously measuring the two normalized in-plane magnetization components in magnetic thin films that allows for the reconstruction of the magnetization angle and the normalized value of the magnetization with subnanosecond temporal resolution. The calibrated method relies on the large contrast associated with magnetization-induced optical second-harmonic generation, permitting measurements with a dynamic range in excess of 25dB. Calibration is achieved by the determination of the relative magnitude and phase of the essential nonlinear optical tensor components, including those of a magneto-optic origin. Ellipsometric determination of the polarization of the second-harmonic signal, when the magnetization is saturated along four in-plane Cartesian directions, is sufficient to determine the second-order nonlinear tensor components. These four directions represent the two saturated states along the longitudinal and transverse directions of the magnetization, respectively. The tensor components are subsequently used to uniquely determine the in-plane magnetization amplitude and direction.
Impurity ion density measurements at the plasma edge of ASDEX Upgrade using lithium beam charge exchange spectroscopy
Authors: Wolfrum E. , Schweinzer J. , Reich M. , Horton L. D. , Maggi C. F.
Published: March 2006

The method of lithium-beam charge exchange spectroscopy is used to determine the density of C6+ and He2+ impurity ions at the edge of the ASDEX Upgrade tokamak plasma. Spectrally resolved measurements are used. l-level resolved atomic capture cross sections are corrected for collisional mixing. The absolute calibration relies on simultaneous beam emission spectroscopy. Together with detailed beam attenuation modeling, impurity ion densities can be measured with good accuracy.
Pointing of laser-accelerated proton beams
Authors: Schreiber J. , Ter-Avetisyan S. , Risse E. , Kalachnikov M. P. , Nickles P. V. , Sandner W. , Schramm U. , Habs D. , Witte J. , Schnürer M.
Published: March 2006

Small fluctuations in the acceleration sheath change the pointing of a proton beam accelerated from the rear side of a laser irradiated thin aluminum foil. The proton acceleration was produced with 40fs pulses of a Ti:sapphire laser at an intensity of approximately 1019W∕cm2. This observation has been made with a high spatial resolution Thomson spectrometer. The proton beam pointing has appeared stable in the energy range between the high energy cutoff (3MeV) and 50% of this value. Deviations of the beam position at lower energies changes in a range of 0–3mrad. The recorded pictures show wiggled and continuous proton traces which imply a release of the proton beam from the acceleration zone with a velocity chirp.
Vibrations of the “beetle” scanning probe microscope: Identification of a new mode, generalized analysis, and characterization methodology
Authors: Brukman Matthew J. , Carpick Robert W.
Published: March 2006

The prediction and understanding of structural resonances are required to optimize scanning probe microscope (SPM) design. Here, Euler beam theory is applied to the beetle-style SPM to derive analytic functions for the natural frequencies of three significant modes of vibration as a general function of the microscope shape, materials, and dimensions. In the first mode, the three piezoelectric legs vibrate transversely and the scanhead moves from side to side. In the second, the legs bend circumferentially and the scanhead rotates about its center. These modes have been identified previously, but here the mechanics analysis is presented in an improved form where the inertia of the piezo legs is considered, constraints on the shape of the central supporting disk are lifted, and appropriate boundary conditions are defined and enforced. In addition, we discuss a third mode that has not been previously identified. In this lowest frequency mode, two legs pivot about the stationary third leg. The predictions are tested against experimental data obtained from an atomic force microscope (AFM) built in our laboratory. We show that the mode frequencies can be determined easily using in situ motion of the AFM cantilever itself. Predicted frequencies are in good agreement with experimental results, although unpredicted modes are also observed. The simple closed-form solutions allow the designer to make quantitative comparisons when choosing the materials and dimensions used in the SPM design. Two new design criteria emerge from the analysis for optimizing the resonant response of the “beetle” scanhead: (1) the wall thickness τ of the piezo legs should be minimized, with their mean diameters increasing as τ−1 and (2) the distance between the legs and the center of the scanhead should be adjusted to optimize the rotation mode eigenfrequency.
Magnetron-based source of neutral metal vapors for photoelectron spectroscopy
Authors: Tchaplyguine M. , Peredkov S. , Svensson H. , Schulz J. , Öhrwall G. , Lundwall M. , Rander T. , Lindblad A. , Bergersen H. , Svensson S. , Gisselbrecht M. , Sorensen S. L. , Gridneva L. , Mårtensson N. , Björneholm O.
Published: March 2006

The construction of a magnetron-based source for neutral metal vapors is presented. The first photoelectron spectroscopy experiments with the source using synchrotron radiation at MAX-lab, Sweden are described. Photoelectron spectra of atomic copper, silver, and nickel are reported with an 80meV resolution for Cu and Ag, previously not achieved in experiments using synchrotron light.
Development of symmetry-resolved zero-kinetic-energy photoelectron spectroscopy for probing multielectron processes
Authors: Gejo T. , Nakamura E. , Shigemasa E.
Published: March 2006

A new experimental setup for probing multielectron processes in molecular inner-shell ionization regions has been developed. Symmetry-resolved zero-kinetic-energy (ZEKE) spectra have been measured by scanning the photon energy along with monitoring the intensity of the coincidence signals between ZEKE electrons and fragment ions detected at 0° and 90° relative to the electric vector of the light. The actual performance of the method is illustrated by using it to reveal the symmetry decomposition of the multielectron processes, such as double excitations and shake-up satellites, in the K-shell ionization region of nitrogen.
Hard x-ray and hot electron environment in vacuum hohlraums at the National Ignition Facility
Authors: McDonald J. W. , Suter L. J. , Landen O. L. , Foster J. M. , Celeste J. R. , Holder J. P. , Dewald E. L. , Schneider M. B. , Hinkel D. E. , Kauffman R. L. , Atherton L. J. , Bonanno R. E. , Dixit S. N. , Eder D. C. , Haynam C. A. , Kalantar D. H. , Koniges A. E. , Lee F. D. , MacGowan B. J. , Manes K. R. , Munro D. H. , Murray J. R. , Shaw M. J. , Stevenson R. M. , Parham T. G. , Van Wonterghem B. M. , Wallace R. J. , Wegner P. J. , Whitman P. K. , Young B. K. , Hammel B. A. , Moses E. I.
Published: March 2006

Time resolved hard x-ray images (hv>9keV) and time integrated hard x-ray spectra (hv=18–150keV) from vacuum hohlraums irradiated with four 351nm wavelength National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technol. 26, 755 (1994)] laser beams are presented as a function of hohlraum size, laser power, and duration. The hard x-ray images and spectra provide insight into the time evolution of the hohlraum plasma filling and the production of hot electrons. The fraction of laser energy detected as hot electrons (Fhot) shows a correlation with laser intensity and with an empirical hohlraum plasma filling model. In addition, the significance of Au K-alpha emission and Au K-shell reabsorption observed in some of the bremsstrahlung dominated spectra is discussed.
Nanolithography by elastomeric scattering mask: An application of photolithographic standing waves
Authors: Kostovski Gorgi , Mitchell Arnan , Holland Anthony , Fardin Ernest , Austin Michael
Published: March 2006

An application is demonstrated for the much maligned standing wave in photolithography that is responsible for the sidewall corrugations in photoresist patterns. We demonstrate the realization of a polydimethylsiloxane (PDMS) scattering mask through the casting of these sidewall corrugations and their application as the masking components in an otherwise transparent bulk of PDMS. Photoresist structures with widths in the order of 80nm are realized by the application of this mask, demonstrating excellent correlation with the lateral depths of the sidewall corrugations. The continuity of the sidewall corrugations around corners makes both straight and curved lines realizable with equal simplicity.
First-principles calculations on magnetic properties of interface-rippled Co∕α-Al2O3∕Co
Authors: Kim Chiho , Chung Yong-Chae
Published: March 2006

The effects of the interface fluctuations on the magnetic properties of a Co∕α-Al2O3∕Co magnetic tunnel junction were intensively investigated using first-principles calculations. Hybridization of Co-3d and O-2p orbitals resulted in the covalent bonds between Co and three O atoms at the interface of Co(111)∕α-Al2O3(0001) and, subsequently, interfacial Co atoms became undulated as much as 34.6% of the interlayer distance measured in the z direction. The magnetic moment of Co atoms at the rippled interface was enhanced to 1.95μB, while the value of the other ferromagnetic Co atoms remained unchanged. Significantly induced minority-spin density of states at the Fermi energy of the Co-interface atoms led to a highly negative spin polarization, −52.0%, at the junction interface. Interestingly, the spin polarization value for the barrier layer was in the range of −6.3%–59.2%.
Effects of Ag/indium tin oxide contact to a SiC doping layer on performance of Si nanocrystal light-emitting diodes
Authors: Huh Chul , Park Nae-Man , Shin Jae-Heon , Kim Kyung-Hyun , Kim Tae-Youb , Cho Kwan Sik , Sung Gun Yong
Published: March 2006

We report on the effects of a very thin Ag (2.5nm) interlayer between the indium tin oxide (ITO) current spreading layer and a SiC doping layer on silicon nanocrystals (nc-Si) embedded in silicon nitride film on the electrical and optical performance of the light-emitting diodes (LEDs). The forward voltage at a current of 20mA of the nc-Si LED with a Ag interlayer was decreased by 2.5V compared to that of the nc-Si LED without one due to the decrease in the contact resistance. In addition, the light output power of the nc-Si LED with a Ag interlayer was also enhanced by 40%. This result strongly indicates that the Ag/ITO contact scheme can serve as a highly promising contact scheme to a SiC film for the realization of the nc-Si LEDs with a high efficiency.
Atomic structure of (111) SrTiO3∕Pt interfaces
Authors: Schmidt Steffen , Klenov Dmitri O. , Keane Sean P. , Lu Jiwei , Mates Thomas E. , Stemmer Susanne
Published: March 2006

Atomic resolution high-angle annular dark field (HAADF) imaging in scanning transmission electron microscopy was used to investigate the interface atomic structure of epitaxial, (111) oriented SrTiO3 films on epitaxial Pt electrodes grown on (0001) sapphire. The cube-on-cube orientation relationship of SrTiO3 on Pt was promoted by the use of a Ti adhesion layer underneath the Pt electrode. While a Ti-rich Pt surface was observed before SrTiO3 growth, HAADF images showed an atomically abrupt SrTiO3∕Pt interface with no interfacial layers. The SrTiO3 films contained two twin variants that were related by a 180° rotation about the ⟨111⟩ surface normal. HAADF images showed two different interface atomic arrangements for the two twins. The role of Ti in promoting (111) epitaxy and the implications for the dielectric properties are discussed.
Spectral tuning of plasmon-enhanced silicon quantum dot luminescence
Authors: Biteen Julie S. , Lewis Nathan S. , Atwater Harry A. , Mertens Hans , Polman Albert
Published: March 2006

In the presence of nanoscale silver island arrays, silicon quantum dots exhibit up to sevenfold luminescence enhancements at emission frequencies that correspond to the collective dipole plasmon resonance frequency of the Ag island array. Using electron-beam lithography to alter the pitch and particle diameter, this wavelength-selective enhancement can be varied as the metal array resonance wavelength is tuned from 600to900nm. The luminescence intensity enhancement upon coupling is attributed to an increase in the radiative decay rate of the silicon quantum dots.
Formation of ZnO nanoparticles and α-AgI nanocrystals embedded in superionic glass nanocomposites
Authors: Bhattacharya S. , Ghosh A.
Published: March 2006

We have reported the formation of ZnO nanoparticles and α-AgI nanocrystals embedded in the glass matrix in the 0.70AgI–0.15Ag2O–0.15[xZnO–(1−x)MoO3], x=0.05–0.30, glass nanocomposites from x-ray diffraction, field emission scanning electron microscopy, and high resolution transmission electron microscopy patterns. Fourier transform infrared spectra have revealed the strong partial covalency due to the presence of Ag+ and MoO42− ions. It is observed that the variation of the conductivity of the composites is well correlated to their structural behavior. A structural model to account for the electrical properties has been proposed.
Adjustable pretilt angle of nematic 4-n-pentyl-4′-cyanobiphenyl on self-assembled monolayers formed from organosilanes on square-wave grating silica surfaces
Authors: Chiou Da-Ren , Yeh Kuan-Yu , Chen Li-Jen
Published: March 2006

The square-wave grating silica surfaces are fabricated by soft embossing silica sol-gel precursor on glass substrates with an elastomeric polydimethylsiloxane mold. The patterned silica surface could induce the planar alignment of liquid crystal 4-n-pentyl-4′-cyanobiphenyl (5CB) along the direction of microgrooves but with no pretilt angle. The pretilt angle of 5CBs is adjusted from 0° to 90° by the further deposition of organosilane self-assembled monolayers with different functional end-groups on the patterned silica surfaces.
Stability of strained H:Si(105) and H:Ge(105) surfaces
Authors: Ciobanu Cristian V. , Briggs Ryan M.
Published: March 2006

We report atomic scale studies of the effect of applied strain and hydrogen environment on the reconstructions of the (105) Si and Ge surfaces. Surface energy calculations for monohydride-terminated (001) and (105) reconstructions reveal that the recently established single-height rebonded model is unstable not only with respect to (001) but also in comparison with other monohydride (105) structures. This finding persists for both Si and Ge, for applied biaxial strains from −4% to 4%, and for nearly the entire relevant domain of the chemical potential of hydrogen, thus providing thermodynamic arguments for the experimentally observed H-induced destabilization of the Ge∕Si(105) surface.
Organic nonvolatile memory by dopant-configurable polymer
Authors: Lai Qianxi , Zhu Zuhua , Chen Yong , Patil Satish , Wudl Fred
Published: March 2006

We report an organic, nonvolatile memory based on dopant concentration-induced conductance changes in a conjugated polymer. Consisting of a polymer poly [2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV)/ionic conductor (RbAg4I5) bilayer sandwiched between two metal electrodes, the device is electrically switched between its low-conductance “off” state and high-conductance “on” state reversibly and repeatedly with on/off ratios above two orders of magnitude and pulse durations as short as 1μs when a voltage exceeding its threshold values (>+3.5V or <−3.8V) is applied. The conductance change is attributed to the injection/depletion of iodide dopant ions in the MEH-PPV layer by the applied electric field.
Control of p- and n-type conductivities in P doped ZnO thin films by using radio-frequency sputtering
Authors: Yu Zhi Gen , Wu Ping , Gong Hao
Published: March 2006

The conduction type of P doped ZnO thin films using Zn3P2 dopant source can be controlled by adjusting the oxygen partial pressure by means of radio-frequency sputtering. Under an optimal oxygen partial pressure of 5%, p-type ZnO thin films were obtained with a hole concentration of 1.93×1016–3.84×1019cm−3. Under a growth condition of extremely low oxygen partial pressure, P doped ZnO thin films exhibit n-type conduction with a hole concentration of 8.34×1017–3.1×1019cm−3. This research not only achieved significant technical advance in the fabrication of p-type ZnO but also gained critical advance in fundamental understanding of the governing mechanism of p-type ZnO.
Sn
O
2
nanoparticles in silica: Nanosized tools for femtosecond-laser machining of refractive index patterns
Authors: Paleari A. , Franchina E. , Chiodini N. , Lauria A. , Bricchi E. , Kazansky P. G.
Published: March 2006

We show that SnO2 nanoclusters in silica interact with ultrashort infrared laser pulses focused inside the material generating a hydrostatic compression and photoelastic response of the surrounding glass. This effect, together with the laser-induced nanocluster amorphization, gives rise to positive or negative refractive-index changes, up to 10−2, depending on the beam-power density. This result points out a wide tuning of the refractive index patterns obtainable in silica-based optical technology.
Changes in soil water content under annual- and perennial-based pasture systems in the wheatbelt of southern New South Wales
Authors: Sandral G. A. , Dear B. S. , Virgona J. M. , Swan A. D. , Orchard B. A.
Published: March 2006

Nine pasture treatments differing in species composition were monitored for changes in soil water content at a depth of 0.10–1.70 m, at 2 sites (Kamarah and Junee), in the wheatbelt of eastern Australia. Treatments containing perennial species, viz. lucerne (Medicago sativa L.), phalaris (Phalaris aquatica L.), cocksfoot (Dactylis glomerata L.), mixture (lucerne + phalaris + cocksfoot), wallaby grass (Austrodanthonia richardsonii Cashmore.), and lovegrass (Eragrostis curvula (Schrader) Nees.), were sown with subterranean clover (Trifolium subterraneum L.). In addition, 3 treatments based solely on annual species were examined: subterranean clover (sown by itself and kept weed-free with herbicides), annual (sown to subterranean clover but weed invasion not controlled), and serradella (Ornithopus compressus L.). The experiment was conducted from 1994–97 at the Junee site (annual average rainfall 550 mm/year) and from 1995–97 at the Kamarah site (annual average rainfall 450 mm per year).
At the higher rainfall site (Junee), there were few differences among pasture types in soil water content to 0.70 m. Below 0.70 m the soil profile was drier under all the perennial swards than under the annual pasture treatments by the end of the 4-year pasture phase. At the drier Kamarah site, where the pasture phase was shorter due to an initial sowing failure, all the perennials, except cocksfoot, dried the profile below 1.05 m. At both sites, lucerne dried the 1.05–1.70 m section of the soil profile more rapidly than the other perennials, which apparently took longer to reach this depth.
At the Junee site, the soil water deficit in May (SWD(MAY), defined as field capacity (mm) – stored soil water (mm) at the beginning of May) was largest in the phalaris, mixture, lucerne, and cocksfoot treatments (155–162 mm), whereas as under a pasture of subterranean clover alone, SWD(MAY) was only 89 mm. At the drier Kamarah site, the largest SWD(MAY) was created by the lovegrass (114 mm) and lucerne (107 mm) treatments. The cocksfoot and subterranean clover treatments created the smallest SWD(MAY) at this site, at 79 and 72 mm, respectively.
The study showed that currently available C3 and C4 perennial grasses can be as effective as lucerne in drying the soil profile to 1.70 m in the 450–600 mm rainfall areas of the southern NSW wheatbelt, creating a dry soil buffer to reduce the risk of deep drainage during subsequent cropping phases. As the rate at which grasses dried the profile was slower than lucerne, pastures based on perennial grasses may have to be retained longer to achieve the same level of dewatering.
Consequences of rainfall during summer - autumn fallow on available soil water and subsequent drainage in annual-based cropping systems
Authors: Dolling P. J. , Fillery I. R. P. , Ward P. R. , Asseng S. , Robertson M. J.
Published: March 2006

This paper investigates factors controlling soil water content changes during the non-growing summer–autumn season or fallow (December–May) in annual farming systems in southern Western Australia. This was achieved by examining variation in available soil water storage to a depth of 1.0–1.5 m at 3 sites within 13 seasons. Reasons for the variation were examined using the Agricultural Production Systems Simulator (APSIM). This paper also investigated whether water accumulation during the summer–autumn period (fallow) contributed to drainage during the following growing season (May–November). This was achieved by determining the relationship between soil water content at the end of the fallow period (1 May) and the amount of drainage below 2.5 m by using APSIM coupled to historical weather records at 3 locations.
At the end of the fallow, 24 mm (or 25%) of rain falling during the fallow was retained in the soil. Evaporation was the main loss of soil water during fallow periods (mean of 60 mm). Other losses included transpiration from plant cover (mean of 12 mm) and drainage below the root zone and runoff (combined mean of 13 mm). Evaporation and transpiration losses of soil water were concentrated in the surface 0.3 m. The use of APSIM to determine changes in the soil water content during the fallow indicated the importance of plants to soil water losses, the potential for higher evaporation than previously reported, and the possibility of an extended period (4–6 weeks) of drainage in sandy soils after large rainfall events (>50 mm).
Soil water accumulation during the fallow period had a significant effect on simulated drainage under wheat in the following growing season. By the end of fallow there was limited ability of the soil to store water before drainage occurred due to rainfall during the fallow and the small soil water deficit under annual farming systems (1–67 mm). A 1-mm increase in soil wetness at the end of the fallow resulted in a 0.7–1-mm increase in simulated drainage during the growing season.
Structure of human Wilson protein domains 5 and 6 and their interplay with domain 4 and the copper chaperone HAH1 in copper uptake
Authors: Achila David , Banci Lucia , Bertini Ivano , Bunce Jennifer , Ciofi-Baffoni Simone , Huffman David L.
Published: March 2006

Human Wilson protein is a copper-transporting ATPase located in the secretory pathway possessing six N-terminal metal-binding domains. Here we focus on the function of the metal-binding domains closest to the vesicular portion of the copper pump, i.e., domain 4 (WLN4), and a construct of domains 5 and 6 (WLN5–6). For comparison purposes, some experiments were also performed with domain 2 (WLN2). The solution structure of apoWLN5–6 consists of two ferredoxin folds connected by a short linker, and
15
N relaxation rate measurements show that it behaves as a unit in solution. An NMR titration of apoWLN5–6 with the metallochaperone Cu(I)HAH1 reveals no complex formation and no copper exchange between the two proteins, whereas titration of Cu(I)HAH1 with WLN4 shows the formation of an adduct that is in fast exchange on the NMR time scale with the isolated protein species as confirmed by
15
N relaxation data. A similar interaction is also observed between Cu(I)HAH1 and WLN2; however, the relative amount of the adduct in the protein mixture is lower. An NMR titration of apoWLN5–6 with Cu(I)WLN4 shows copper transfer, first to WLN6 then to WLN5, without the formation of an adduct. Therefore, we suggest that WLN4 and WLN2 are two acceptors of Cu(I) from HAH1, which then somehow route copper to WLN5–6, before the ATP-driven transport of copper across the vesicular membrane.
Connexin30.2 containing gap junction channels decelerate impulse propagation through the atrioventricular node
Authors: Kreuzberg Maria M. , Schrickel Jan W. , Ghanem Alexander , Kim Jung-Sun , Degen Joachim , Janssen-Bienhold Ulrike , Lewalter Thorsten , Tiemann Klaus , Willecke Klaus
Published: March 2006

In the mammalian heart, gap junction channels between electrically coupled cardiomyocytes are necessary for impulse propagation and coordinated contraction of atria and ventricles. Recently, mouse connexin30.2 (Cx30.2) was shown to be expressed in the cardiac conduction system, predominantly in sinoatrial and atrioventricular (AV) nodes. The corresponding gap junctional channels expressed in HeLa cells exhibit the lowest unitary conductance (9 pS) of all connexin channels. Here we report that Cx30.2 slows down the propagation of excitation through the AV node. Mice expressing a LacZ reporter gene instead of the Cx30.2 coding region (Cx30.2
LacZ/LacZ
) exhibit a PQ interval that is ≈25% shorter than in WT littermates. By recording atrial, His, and ventricular signals with intracardiac electrodes, we show that this decrease is attributed to significantly accelerated conduction above the His bundle (atrial-His interval: 27.9 ± 5.1 ms in Cx30.2
LacZ/LacZ
versus 37.1 ± 4.1 ms in Cx30.2
+/+
mice), whereas HV conduction is unaltered. Atrial stimulation revealed an elevated AV-nodal conduction capacity and faster ventricular response rates during induced episodes of atrial fibrillation in Cx30.2
LacZ/LacZ
mice. Our results show that Cx30.2 contributes to the slowdown of impulse propagation in the AV node and additionally limits the maximum number of beats conducted from atria to ventricles. Thus, it is likely to be involved in coordination of atrial and ventricular contraction and to fulfill a protective role toward pathophysiological states such as atrial tachyarrhythmias (e.g., atrial fibrillation) by preventing rapid conduction to the ventricles potentially associated with hemodynamic deterioration.