bluuebunny/crossref_metadata_2025 huggingface dataset:
Register variation, truncation, and subject omission in English and in French
Authors: Haegeman Liliane
Published: September 2008

This paper concerns the null subject phenomenon attested in abbreviated written registers in English and in French (diaries, instructions) and in informal spoken English. Neither a pro drop analysis nor a topic drop analysis will account for the incompatibility of the English null subjects withwh-preposing and with embedded contexts. Rizzi's (1994) analysis for null subjects in child production is adopted here in a slightly modified form. Like the early null subject, the (adult) null subject in abbreviated registers is an antecedentless empty category in the A-specifier of the root. Null subjects depend on the truncation of CP, which turns the specifier of IP into the highest specifier of the clause. The paper explores apparent noninitial null subjects, i.e. null subjects co-occurring with preposed adjuncts (though not arguments) and shows that these can be accounted for in terms of partial truncation within an articulated CP. The null subject is an antecedentless empty category in the (A-)specifier of an AGR-projection dominating the Topic Projection. The incompatibility withwh-preposing and with argument preposing is accounted for. In a more speculative vein I also consider the deletion ofbein the abbreviated styles, which I claim can also be analysed in terms of truncation.
The choice between infinitives andthat-clauses afterbelieve
Authors: Noël Dirk
Published: September 2008

Intuitive, sentence-based approaches have so far failed to account conclusively for the choice between athat-complement and an infinitival complement afterbelieve-type verbs, in sentences likeI believe something like this to be very much the case(EB2 1297) andI believe that monetary union is political union, and that the creation of a single currency is federalism(HHW 13012). Syntactically, there is no free variation between the two patterns, since there are a number of formal restrictions on the infinitival complements that do not apply to thethat-complements. But is there a semantic motivation behind the choice in cases when there are no formal reasons for choosing one or the other? This paper surveys a few earlier suggestions to this effect, but argues that a corpus-based approach unmistakably suggests that factors of a textual nature are at work, rather than purely semantic ones.2
On subject-orientation in English -lyadverbs
Authors: Valera Salvador
Published: September 2008

This paper challenges the view that subject-orientation in English de-adjectival -lyadverbs is a syntactic attribute, and favours the hypothesis that orientation is, rather, a lexico-semantic feature. An important part of the evidence supporting this hypothesis derives from the examination of constructions in which an -lyadverb modifies an adjectival head (as inhis genially informal manner) and displays a (potential) orientation to a co-occurring noun. The discussion is based on examples from the LOB Corpus.
IS IT GOOD FOR THE JEWS? A RESPONSE TO BRIAN KLUG'S ‘A PLEA FOR DISTINCTIONS: DISENTANGLING ANTI-AMERICANISM FROM ANTI-SEMITISM’
Authors: Meisels Tamar
Published: September 2008

Tamar Meisels responds to the preceding article.
A RESPONSE TO TAMAR MEISELS
Authors: Klug Brian
Published: September 2008

Our third and final article on the the Israel/Palestine conflict and anti-semitism.
REPLY TO BLACKBURN
Authors: Swinburne Richard
Published: September 2008

Richard Swinburne responds to Simon Blackburn.
Porous compaction in transient creep regime and implications for melt, petroleum, and CO2 circulation
Authors: Chauveau B. , Kaminski E.
Published: September 2008

Liquid segregation through a porous medium depends on the ability of the matrix to deform and compact. Earth's materials have a complex rheology, in which the balance between the elastic and viscous contribution to the deformation is time‐dependent. In this paper, we propose a Burger‐type model to investigate the implications of transient rheology for viscous compaction of a porous material. The model is characterized by three dimensionless parameters: (1) the Deborah number, De, defined as the ratio of an elastic timescale over the compaction timescale, (2) the ratio of the transient and steady viscosities, λμ, and (3) the ratio of the transient and steady elastic moduli, λG. For De < 10−2 the compaction occurs in the classic viscous mode, and solitary waves (magmons) are generated. For larger De, compaction is mainly controlled by λμ. For small transient viscosity, compaction occurs in an elastic mode, and shock waves are generated. For increasing λμ, two new regimes are observed, first “shaggy” shock waves and then “polytons”. Shaggy shock waves are characterized by the presence of secondary peaks at the wave propagation front. The length scale of the peaks is a decreasing function of λG, and their amplitude decreases along the propagation. In the polytons regime, the peaks tend to detach and mimic the behavior of solitary waves. Polytons and shaggy shock waves are expected both in the mantle and in sedimentary basins. Polytons will require a particular attention as they imply larger extraction velocities and smaller compaction length scales than the usual magmons.
Retrieval of aerosol optical properties from OMI radiances using a multiwavelength algorithm: Application to western Europe
Authors: Curier R. L. , Veefkind J. P. , Braak R. , Veihelmann B. , Torres O. , de Leeuw G.
Published: September 2008

The Ozone Monitoring Instrument (OMI) multiwavelength algorithm has been developed to retrieve aerosol optical depth using OMI‐measured reflectance at the top of the atmosphere. This algorithm was further developed by using surface reflectance data from a field campaign in Cabauw (The Netherlands), a new cloud‐screening method, and a global aerosol database derived from the aerosol transport model TM5. The first results from an application of this algorithm over western Europe are presented. The OMI‐retrieved aerosol optical depth is evaluated by comparison with both ground‐based measurements from Aerosol Robotic Network (AERONET) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. The various aerosol optical depth values compare favorably, except in situations where large changes occur in the surface properties, which is illustrated over the Iberian peninsula. OMI and MODIS aerosol optical depth are well correlated (with a correlation coefficient of 0.66 over land and 0.79 over sea), although the multiwavelength algorithm appears to overestimate the aerosol optical depth values with respect to MODIS. The multiwavelength algorithm performs better over sea than over land. Qualitatively, the multiwavelength algorithm well reproduces the expected spatial aerosol optical depth gradient over western Europe.
High‐precision spectroscopy of 32S, 33S, and 34S sulfur dioxide: Ultraviolet absorption cross sections and isotope effects
Authors: Danielache Sebastian O. , Eskebjerg Carsten , Johnson Matthew S. , Ueno Yuichiro , Yoshida Naohiro
Published: September 2008

We report measurements of the ultraviolet absorption cross sections of 32SO2, 33SO2, and 34SO2, recorded from 30,300 to 52,500 cm−1 (330 to 190 nm) at 293 K with a resolution of 25 cm−1. The 33SO2 sample was produced by the combustion of isotopically enriched 33S while the 34SO2 and natural abundance samples were obtained from commercial manufacturers. The spectrum of the natural abundance sample is in agreement with previously published spectra. The spectra of the isotopically pure species were retrieved using the isotopic composition of the samples. The 32SO2, 33SO2, and 34SO2 absorption spectra show rich vibrational structure, and the positions and widths of the peaks change with isotopic substitution in a complex fashion. The results imply that large wavelength‐dependent and broadband isotopic fractionations are associated with the UV photolysis of SO2.
Analytical relationships between atmospheric carbon dioxide, carbon emissions, and ocean processes
Authors: Goodwin Philip , Follows Michael J. , Williams Richard G.
Published: September 2008

Carbon perturbations leading to an increase in atmospheric CO2 are partly offset by the carbon uptake by the oceans and the rest of the climate system. Atmospheric CO2 approaches a new equilibrium state, reached after ocean invasion ceases after typically 1000 years, given by PCO2 = P0exp(δIχ/IB), where P0 and PCO2 are the initial and final partial pressures of atmospheric CO2, δIχ is a CO2 perturbation, and IB is the buffered carbon inventory of the air‐sea system. The perturbation, δIχ, includes carbon emissions and changes in the terrestrial reservoir, as well as ocean changes in the surface carbon disequilibrium and fallout of organic soft tissue material. Changes in marine calcium carbonate, δICaCO3, lead to a more complex relationship with atmospheric CO2, where PCO2 is changed by the ratio PCO2 = P0{IO(A − C)/(IO(A − C) − δICaCO3)} and then modified by a similar exponential relationship, where IO(A − C) is the difference between the inventories of titration alkalinity and dissolved inorganic carbon. The overall atmospheric PCO2 response to a range of perturbations is sensitive to their nonlinear interactions, depending on the product of the separate amplification factors for each perturbation.
A first approach to the characterization of solute transfer from soil to runoff in transient shallow flows
Authors: Nofuentes M. , Polo M. J.
Published: September 2008

Solute transfer from soil to runoff is a complex process in which soil properties and flow runoff conditions interact. This process has been described when the runoff is generated from rainfall, but there has been very little research into sudden flooding of soil by runoff from upstream water sources. This article outlines the experimental design used to describe this process in shallow water flows, and to study the relationships between water flow conditions and the transfer process. Experimental work was carried out in a laboratory flume under different water inflow rates over a narrow fringe along the soil surface with a conservative tracer. The transfer process from the soil was described as an exponential load function, with a decreasing duration and an increasing load to the surface flow as the water inflow rate increased. Non‐linearity was tested and parameterized in a final run to include upstream loads to the flow.
Geomagnetic excursions: Knowns and unknowns
Authors: Roberts Andrew P.
Published: September 2008

Geomagnetic excursions are short‐lived episodes when Earth’s magnetic field deviates into an intermediate polarity state. Understanding the origin, frequency, amplitude, duration, and field behavior associated with excursions is a forefront research area within solid earth geophysics. Recent advances in excursion research are summarized here, and key further research is suggested to resolve major unanswered questions. Improving the global distribution of excursion records, particularly from the southern hemisphere, obtaining high‐resolution sedimentary excursion records with good age control from sites with sedimentation rates >10 cm/kyr, obtaining volcanic excursion records coupled with high‐precision geochronology, and estimating excursion duration with high chronological precision will all facilitate hypothesis testing concerning the deep earth dynamics that generate geomagnetic excursions.
Electron thermal effects in standing shear Alfvén waves
Authors: Damiano P. A. , Wright A. N.
Published: September 2008

Recent hybrid MHD‐kinetic electron simulations of Field Line Resonances have illustrated that the acceleration of electrons to carry the field aligned current can dissipate a significant amount of wave energy over only half an Alfvén cycle. This was done in the limit of colder electron temperatures, and in the present study we extend this to consider temperatures of up to several hundred eV. It is found that mirror force effects enhance both the parallel electric field needed to support the given current as well as the dissipation associated with the acceleration of the electrons to carry it. The current‐voltage (C‐V) relation appears consistent with the Knight relation for a portion of the evolution but then saturates with the decline of electrons within the loss cone.
Assessing land‐atmosphere coupling using soil moisture from the Global Land Data Assimilation System and observational precipitation
Authors: Zhang Jingyong , Wang Wei‐Chyung , Wei Jiangfeng
Published: September 2008

Precipitation analysis and soil moisture from the Global Land Data Assimilation System (GLDAS) are used to assess the land‐atmosphere coupling in boreal summer. Correlations between antecedent soil moisture and precipitation suggest that regions of strong land‐atmosphere coupling lie mainly in arid to semiarid transition zones or in semihumid forest to grassland transition zones. They consist of central Eurasia, the region from Mongolia to northern China, southwest China, the Sahel, the northern continental United States, and southern Europe. It is found that over these regions, positive soil moisture feedback accounts for typically 10–20% of the variance of monthly precipitation anomalies with the feedback efficiency of the order of 0.3–0.9 mm month−1 (0.1 standardized soil moisture)−1. While soil moisture feedback is dominated by the positive sign, negative feedback may exist in some areas, such as India and the western part and Quebec province of Canada. Generally, the land‐atmosphere coupling strength estimated from the GLDAS data agrees well with those from the observational soil moisture in Illinois and the European Centre for Medium‐Range Weather Forecasts 40‐year reanalysis (ERA‐40) soil moisture product. Physical mechanisms responsible for the findings are further discussed. This study provides a Northern Hemisphere distribution of the land‐atmosphere coupling strength, which can be used to test the model simulations on monthly to seasonal time scales.
Submillennial‐to‐millennial variability of diatom production off Mauritania, NW Africa, during the last glacial cycle
Authors: Romero Oscar E. , Kim Jung‐Hyun , Donner Barbara
Published: September 2008

The low‐latitude upwelling regime off the Mauritanian coast in the subtropical NE Atlantic accounts for a significant part of global export production. Although productivity variations in coastal upwelling areas are usually attributed to changes in wind stress and upwelling intensity, productivity dynamics off Mauritania are less straightforward because of the complex atmospheric and hydrographic setting. Here we integrate micropaleontological (diatoms) and geochemical (bulk biogenic sediment components, X‐ray fluorescence, and alkenones) proxies to examine on submillennial‐to‐millennial changes in diatom production that occurred off Mauritania, NW Africa, for the last 25 ka. During the Last Glacial Maximum (LGM, 19.0–23.0 ka B.P.), moderate silicate content of upwelled waters coupled with weakened NE trade winds determined moderate diatom productivity. No significant cooling is observed during the LGM, suggesting that our alkenone‐based SST reconstruction represents a local, upwelling‐related signal rather than a global insolation related one. Extraordinary increases in diatom and opal concentrations during Heinrich event 1 (H1, 15.5–18.0 ka B.P.) and the Younger Dryas (YD, 13.5–11.5 ka B.P.) are attributed to enhanced upwelling of silica‐rich waters and an enlarged upwelling filament, due to more intense NE trade winds. The synchronous increase of CaCO3 and K intensity and the decreased opal and diatoms values mark the occurrence of the Bølling/Allerød (BA, 13.5–15.5 ka B.P.) due to weakened eolian input and more humid conditions on land. Although the high export of diatoms is inextricably linked to upwelling intensity off Mauritania, variability in the nutrient content of the thermocline also plays a decisive role.
Organometallic Chemistry
Authors: Timney J A , Butler I R , Wright Dominic S , Brennan J , Sella A , Wheatley Andrew E H , Humphrey M G , Lynam Jason M , Bridgeman A J , King P J , Layfield Richard A , Solan Gregory A , Jelliss Paul , Francis Matthew D , Aldridge Simon , Boss Sally , Cifuentes Marie P , Christie Steve D R
Published: September 2008

Organometallic chemistry is an interdisciplinary science which continues to grow at a rapid pace. Although there is continued interest in synthetic and structural studies the last decade has seen a growing interest in the potential of organometallic chemistry to provide answers to problems in catalysis, synthetic organic chemistry and also in the development of new materials. This Specialist Periodical Report aims to reflect these current interests, reviewing progress in theoretical organometallic chemistry, main group chemistry, the lanthanides and all aspects of transition metal chemistry. Volume 31 covers literature published during 2002. Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading authorities in the relevant subject areas, the series creates a unique service for the active research chemist, with regular, in-depth accounts of progress in particular fields of chemistry. Subject coverage within different volumes of a given title is similar and publication is on an annual or biennial basis.
Angiotensin II modulates CD40 expression in vascular smooth muscle cells
Authors: Souza Heraldo P. , Frediani Denise , Cobra Ana L. , Moretti Ana I. , Jurado Márcia C. , Fernandes Thadeu R. , Cardounel Arturo J. , Zweier Jay L. , Tostes Rita C.
Published: September 2008

The signalling pathway CD40/CD40L (CD40 ligand) plays an important role in atherosclerotic plaque formation and rupture. AngII (angiotensin II), which induces oxidative stress and inflammation, is also implicated in the progression of atherosclerosis. In the present study, we tested the hypothesis that AngII increases CD40/CD40L activity in vascular cells and that ROS (reactive oxygen species) are part of the signalling cascade that controls CD40/CD40L expression. Human CASMCs (coronary artery smooth muscle cells) in culture exposed to IL (interleukin)-1β or TNF-α (tumour necrosis factor-α) had increased superoxide generation and enhanced CD40 expression, detected by EPR (electron paramagnetic resonance) and immunoblotting respectively. Both phenomena were abolished by previous incubation with membrane-permeant antioxidants or cell transfection with p22phoxantisense. AngII (50–200 nmol/l) induced an early and sustained increase in CD40 mRNA and protein expression in CASMCs, which was blocked by treatment with antioxidants. Increased CD40 expression led to enhanced activity of the pathway, as AngII-treated cells stimulated with recombinant CD40L released higher amounts of IL-8 and had increased COX-2 (cyclo-oxygenase-2) expression. We conclude that AngII stimulation of vascular cells leads to a ROS-dependent increase in CD40/CD40L signalling pathway activity. This phenomenon may be an important mechanism modulating the arterial injury observed in atherosclerosis-related vasculopathy.
Polar face dependence of the ultrafast UV reflectivity of ZnO single crystal
Authors: Schneck J. R. , Bellotti E. , Lamarre P. , Ziegler L. D.
Published: September 2008

The transient reflectivity of an ∼40 fs, 340 nm pulse incident on each face of a ZnO single crystal is reported as a function of carrier density. Three exponentially damped carrier relaxation components can be identified in these responses. Only the Zn face reflectivity reveals a subpicosecond decay (200–300 fs) due to electron scattering. In contrast, the O face reflectivity exhibits an ∼2 ps absorptive decay attributed to the trapping of carriers by O-surface defects at the earliest times. The other decay components are consistent with electron cooling via acoustic phonons and exciton recombination for both faces.
Retardation time spectra computed from complex compliance functions
Authors: Domínguez-Espinosa Gustavo , Ginestar Damian , Sanchis Maria J. , Díaz-Calleja Ricardo , Riande Evaristo
Published: September 2008

This work describes the calculation of retardation time spectra by minimization of the square of the differences between experimental compliance results and those recalculated from the spectra. Spectra were computed taking analytical complex dielectric results as the basis of the minimization process. Comparison of the spectra computed from both the complex dielectric permittivity and the dielectric loss with those calculated analytically shows that minimization methods based on complex dielectric permittivity data are more accurate than those based only on loss dielectric results.
Theory of 360° domain walls in thin ferromagnetic films
Authors: Muratov C. B. , Osipov V. V.
Published: September 2008

An analytical and computational study of 360° domain walls in thin uniaxial ferromagnetic films is presented. The existence of stable one-dimensional 360° domain wall solutions both with and without the applied field is demonstrated in a reduced thin film micromagnetic model. The wall energy is found to depend rather strongly on the orientation of the wall and the wall width significantly grows when the strength of the magnetostatic forces increases. It is also shown that a critical reverse field is required to break up a 360° domain wall into a pair of 180° walls. The stability of the 360° walls in two-dimensional films of finite extent is demonstrated numerically and the stability with respect to slow modulations in extended films is demonstrated analytically. These domain wall solutions are shown to play an important role in magnetization reversal. In particular, it is found that the presence of 360° domain walls may result in nonuniqueness of the observed magnetization patterns during repeated cycles of magnetization reversal by pulsed fields.
Radiation tolerance of a high quality synthetic single crystal chemical vapor deposition diamond detector irradiated by 14.8 MeV neutrons
Authors: Pillon M. , Angelone M. , Aielli G. , Almaviva S. , Marinelli Marco , Milani E. , Prestopino G. , Tucciarone A. , Verona C. , Verona-Rinati G.
Published: September 2008

Diamond exhibits many properties such as an outstanding radiation hardness and fast response time both important to design detectors working in extremely radioactive environments. Among the many applications these devices can be used for, there is the development of a fast and radiation hard neutron detector for the next generation of fusion reactors, such as the International Thermonuclear Experimental Reactor project, under construction at Cadarache in France. A technology to routinely produce electronic grade synthetic single crystal diamond detectors was recently developed by our group. One of such detectors, with an energy resolution of 0.9% as measured using an A241m α particle source, has been heavily irradiated with 14.8 MeV neutrons produced by the Frascati Neutron Generator. The modifications of its spectroscopic properties have been studied as a function of the neutron fluence up to 2.0×1014 n/cm2. In the early stage of the irradiation procedure an improvement in the spectroscopic performance of the detector was observed. Subsequently the detection performance remains stable for all the given neutron fluence up to the final one thus assessing a remarkable radiation hardness of the device. The neutron damage in materials has been calculated and compared with the experimental results. This comparison is discussed within the nonionizing energy loss (NIEL) hypothesis, which states that performance degradation is proportional to NIEL.
Effect of applied stress on vacancy segregation near the grain boundary in nickel
Authors: Xiao W. , Liu C. S. , Tian Z. X. , Geng W. T.
Published: September 2008

We report a first-principles density functional theory investigation on the vacancy segregation near the nickel Σ5(210) grain boundary (GB) under applied stress. Our total energy calculations within generalized-gradient approximation reveal that the applied stress can hardly alter the energy preference of a vacancy at different atomic layers away from the GB plane, especially in the range of practical stresses. The segregation enthalpy, nevertheless, gets more (less) significant with the increasing compressive (tensile) stress as a result of the vacancy being smaller in volume at the boundary. Our first-principles result that high-angle tilt GBs in nickel are likely to act as a source (sink) in emitting (absorb) vacancies under a tensile (compressive) stress is not in accordance with the prediction based on a thermodynamic model. The numerical results are discussed with electronic structure analysis.
Monte Carlo modeling of carrier-carrier scattering in semiconductors with nonparabolic bands
Authors: Bonno Olivier , Thobel Jean-Luc
Published: September 2008

An efficient algorithm to account for nonparabolicity in carrier-carrier scattering in an ensemble Monte Carlo simulator is proposed. The major difficulty of modeling intercarrier scattering in semiconductors with nonparabolic bands arises from the two particle momentum and energy conservation laws that have to be simultaneously satisfied. A numerically efficient method is thus proposed to compute the final states accounting for a nonparabolic density of states and included in an ensemble Monte Carlo simulator. The developed algorithm makes use of rejection procedures in order to determine the correct number of scattering events as well as the distribution of the final states. This algorithm is then applied to compute constant-energy contours in various semiconductors, including narrow gap, highly nonparabolic materials, such as InAs. The model is also used to investigate the electron dynamics in an InAs quantum well heterostructure. Our results show that nonparabolicity significantly alters the transient regime since it increases the number of carrier-carrier scattering events. Finally, we investigate the validity of the parabolic approximation in the modeling of a typical GaAs resonant phonon terahertz quantum cascade laser. It is shown that, although electron-electron scattering plays a crucial role in setting the device performance of the laser, the effect of nonparabolicity in this interaction alters only slightly the population inversion while the subband temperatures are increased.
Photoluminescence via plasmon resonance energy transfer in silver nanocomposite glasses
Authors: Jiménez J. A. , Lysenko S. , Liu H.
Published: September 2008

This paper reports the first spectroscopic demonstration of photoluminescence (PL) owing to plasmon resonance energy transfer (PRET) from silver nanoparticles (NPs) to luminescent species in glass. Optical absorption and PL spectroscopy experiments performed on the melt-quenched silver-doped glass indicate the presence of single Ag+ ions, Ag+–Ag+ and Ag+–Ag0 pairs, and Ag NPs. After thermal processing of the material, nonradiative energy transfer from the Ag+–Ag0 luminescent centers to Ag NPs is observed by uniform suppression of band emission and the vanishing of the excitation band associated. Furthermore, evidence for PRET is observed after glass heat treatment by the appearance of a new excitation band near the surface plasmon resonance peak of Ag NPs at about 420 nm, when emission of silver pairs is monitored around 550 nm. In fact, excitation at 420 nm leads to a band emission centered around 530 nm indicating that the excitation of luminescent silver species indeed takes place via PRET. The luminescence is interpreted as arising from a Ag NP→Ag+–Ag0→Ag+–Ag+ energy transfer scheme.
Hopping conductivity in Mn-doped β-FeSi2 single crystals
Authors: Arushanov E. , Lisunov K. G. , Vinzelberg H. , Behr G. , Schumann J. , Schmidt O. G.
Published: September 2008

The article gives a report on resistivity measurements on Mn-doped p-type FeSi2 single crystals and analyzes the data within the framework of different hopping conductivity models. Both the Mott [N. Mott and E. A. Davies, Electron Processes in Non-Crystalline Materials (Clarendon, Oxford, 1979)] and the Shklovskii–Efros [B. I. Shklovskii and A. L. Efros, Electronic Properties o0066 Doped Semiconductors (Springer, Berlin, 1984)] regimes of the variable-range hopping (VRH) conductivity are observed. It is shown that the temperature dependence of the resistivity of Mn-doped β-FeSi2 crystals, which follows a VRH conduction mechanism, can be expressed by a scaling expression of the form ln(ρ/ρ0)=Af(T/Tx). The characteristic and transition temperatures, as well as the complete set of parameters describing the properties of the localized holes (the localization radius, the dielectric permittivity, the width of the Coulomb gap Δ, and the values of the density of states at the Fermi level) are determined. The data above indicate existence of a rigid gap δ in the spectrum of the DOS in addition to Δ and point out to the polaronic nature of the charge carriers in the investigated compound.
Fluorescence detection of DNA using an amorphous silicon p-i-n photodiode
Authors: Pimentel A. C. , Prazeres D. M. F. , Chu V. , Conde J. P.
Published: September 2008

A microdevice based on a thin-film hydrogenated amorphous silicon (a-Si:H) n-i-p photodiode is used to quantify the density of DNA oligonucleotides labeled with a fluorophore in solution, adsorbed, and hybridized on the device surface. Excitation of single-stranded DNA molecules tagged with the fluorophore Alexa Fluor 430 with near UV/blue light results in the emission of visible light at 539 nm. The emitted light produces an electrical signal in the photodetector, allowing the optoelectronic detection and quantification of the DNA molecules. An integrated high-pass filter cuts the excitation light while allowing the collection of the emission light by the photodiode. The detection limit of the present device is of the order of 5 nM in solution. A surface density of the order of 2 pmol/cm2 was measured for DNA targets hybridized to immobilized DNA probes. The sensitivity of the current device is limited by the efficiency of the filtering of the excitation light. The detection concept explored can enable on-chip electronic data acquisition in lab-on-a-chip devices and microarrays.
Quasistatic dielectric and strain characterization of transparent relaxor ferroelectric lead lanthanum zirconate titanate ceramics
Authors: Sabat Ribal Georges , Rochon Paul , Mukherjee Binu K.
Published: September 2008

The relative permittivity and dielectric loss tangent of transparent lead lanthanum zirconate titanate (PLZT) (9.5/65/35) and (9.0/65/35) ceramics were measured as a function of temperature, ranging from −60 to 100 °C, and as a function of frequency, ranging from 0.12 to 5000 kHz. Diffuse maxima were observed in the complex permittivity plots of both PLZT compositions. These maxima correspond to phase transitions from ferroelectric to paraelectric and finally to cubic in the PLZT crystal structure. Second, a Sawyer–Tower circuit was used to determine the electric displacement of each ceramic composition as a function of a dc bias field, ranging from −1.7 to 1.7 MV/m. Third, a Polytech vibrometer was used to measure the longitudinal ac strain response of (9.5/65/35) and (9.0/65/35) PLZT ceramics under various dc bias and ac electric fields with a 120 Hz driving frequency. A maximum piezoelectric strain of 0.8×10−3 m/m occurred for a 0.64 mm thick (9.5/65/35) PLZT at 1.1 MV/m dc and 1.09 MV/m ac peak to peak, and 1.3×10−3 m/m for a 0.54 mm thick (9.0/65/35) PLZT at 1.4 MV/m dc and 0.68 MV/m ac peak-to-peak. Fourier analysis was performed on the raw vibrometer data and the strain response at the second, third, and fourth harmonics were obtained as a function of dc and ac fields. Finally, the measured data were fitted to a theoretical model and the material coefficients for these PLZT compositions were obtained.
A high temperature cell for simultaneous electrical resistance and neutron diffraction measurements
Authors: Engin T. E. , Powell A. V. , Haynes R. , Chowdhury M. A. H. , Goodway C. M. , Done R. , Kirichek O. , Hull S.
Published: September 2008

An in situ cell that allows the electrical resistance of a sample pellet to be measured while performing neutron diffraction experiments has been developed at the ISIS pulsed neutron source. The sample is held between two spring loaded platinum electrodes embedded in a boron nitride clamp assembly with the resistance measured using the four-probe method. An outer quartz glass jacket allows the atmosphere within the sample enclosure to be controlled, and the entire device can be accommodated within a standard ISIS neutron furnace for measurements at temperatures up to 1270 K. The operation of this cell is illustrated using data for the structural, magnetic, and electrical properties of chalcopyrite CuFeS2 collected over the temperature range of 398–873 K on the Polaris powder diffractometer at ISIS.
Fourth-order shear elastic constant assessment in quasi-incompressible soft solids
Authors: Rénier Mathieu , Gennisson Jean-Luc , Barrière Christophe , Royer Daniel , Fink. Mathias
Published: September 2008

In isotropic quasi-incompressible media, an expression of the elastic energy density has been developed as a function of the second-, third-, and fourth-order elastic constants (respectively μ, A, D). Thus the shear nonlinearity parameter βS depends only on these coefficients. In this letter βS is measured using finite amplitude plane shear waves in agar-gelatin based phantoms. Combining the results with recently published measurements of μ and A on the same phantoms, the fourth-order shear elastic constant D is found to be of the order of 10kPa and thus of the same order of magnitude as μ and A.
Atomic structure of the interface between SrTiO3 thin films and Si(001) substrates
Authors: Mi Shao-Bo , Jia Chun-Lin , Vaithyanathan Venu , Houben Lothar , Schubert Jürgen , Schlom Darrell G. , Urban Knut
Published: September 2008

The structure of the SrTiO3/Si interface is determined by high-angle annular dark field imaging in combination with a recently developed technique based on aberration-corrected high-resolution transmission electron microscopy. At the interface, a monolayer of SrO faces the terminating plane of silicon. In this monolayer, the strontium atoms lie above the face-center of four silicon atoms in the terminating plane, and the oxygen atoms are located directly above the terminating silicon atoms. This structure, which is the dominant type of interface structure observed in this system, agrees with one of the interface structures predicted by first-principles calculations.
Multimodal system for harvesting magnetic and mechanical energy
Authors: Dong Shuxiang , Zhai Junyi , Li J. F. , Viehland D. , Priya S.
Published: September 2008

In this letter, we investigate a multimodal system for simultaneous energy harvesting from stray magnetic and mechanical energies by combining magnetoelectric and piezoelectric effects. The system consists of a cantilever beam with tip mass and a magnetoelectric laminate attached in the center of the beam. At 2 Oe magnetic field and mechanical vibration amplitude of 50mg, both at frequency of 20 Hz, the system was found to generate open circuit output voltage of 8 VP.P.. An equivalent circuit model is proposed that predicts a summation effect for both mechanical and magnetic energies.
Eliminating the domain error in local explicitly correlated second-order Møller–Plesset perturbation theory
Authors: Werner Hans-Joachim
Published: September 2008

A new explicitly correlated local MP2-F12 method is proposed in which the error caused by truncating the virtual orbital space to pair-specific local domains is almost entirely removed. This is achieved by a simple modification of the ansatz for the explicitly correlated wave function, which makes it possible that the explicitly correlated terms correct both for the basis set incompleteness error as well as for the domain error in the LMP2. Benchmark calculations are presented for 21 molecules and 16 chemical reactions. The results demonstrate that the local approximations have hardly any effect on the accuracy of the computed correlation energies and reaction energies, and the LMP2-F12 reaction energies agree within 0.1–0.2 kcal/mol with estimated MP2 basis set limits.
Dynamic control of slow water transport by aquaporin 0: Implications for hydration and junction stability in the eye lens
Authors: Jensen Morten Ø. , Dror Ron O. , Xu Huafeng , Borhani David W. , Arkin Isaiah T. , Eastwood Michael P. , Shaw David E.
Published: September 2008

Aquaporin 0 (AQP0), the most abundant membrane protein in mammalian lens fiber cells, not only serves as the primary water channel in this tissue but also appears to mediate the formation of thin junctions between fiber cells. AQP0 is remarkably less water permeable than other aquaporins, but the structural basis and biological significance of this low permeability remain uncertain, as does the permeability of the protein in a reported junctional form. To address these issues, we performed molecular dynamics (MD) simulations of water transport through membrane-embedded AQP0 in both its (octameric) junctional and (tetrameric) nonjunctional forms. From our simulations, we measured an osmotic permeability for the nonjunctional form that agrees with experiment and found that the distinct dynamics of the conserved, lumen-protruding side chains of Tyr-23 and Tyr-149 modulate water passage, accounting for the slow permeation. The junctional and nonjunctional forms conducted water equivalently, in contrast to a previous suggestion based on static crystal structures that water conduction is lost on junction formation. Our analysis suggests that the low water permeability of AQP0 may help maintain the mechanical stability of the junction. We hypothesize that the structural features leading to low permeability may have evolved in part to allow AQP0 to form junctions that both conduct water and contribute to the organizational structure of the fiber cell tissue and microcirculation within it, as required to maintain transparency of the lens.
Slowing down as an early warning signal for abrupt climate change
Authors: Dakos Vasilis , Scheffer Marten , van Nes Egbert H. , Brovkin Victor , Petoukhov Vladimir , Held Hermann
Published: September 2008

In the Earth's history, periods of relatively stable climate have often been interrupted by sharp transitions to a contrasting state. One explanation for such events of abrupt change is that they happened when the earth system reached a critical tipping point. However, this remains hard to prove for events in the remote past, and it is even more difficult to predict if and when we might reach a tipping point for abrupt climate change in the future. Here, we analyze eight ancient abrupt climate shifts and show that they were all preceded by a characteristic slowing down of the fluctuations starting well before the actual shift. Such slowing down, measured as increased autocorrelation, can be mathematically shown to be a hallmark of tipping points. Therefore, our results imply independent empirical evidence for the idea that past abrupt shifts were associated with the passing of critical thresholds. Because the mechanism causing slowing down is fundamentally inherent to tipping points, it follows that our way to detect slowing down might be used as a universal early warning signal for upcoming catastrophic change. Because tipping points in ecosystems and other complex systems are notoriously hard to predict in other ways, this is a promising perspective.
Regulation of cytotoxic T lymphocyte triggering by PIR-B on dendritic cells
Authors: Endo Shota , Sakamoto Yuzuru , Kobayashi Eiji , Nakamura Akira , Takai Toshiyuki
Published: September 2008

Priming of cytotoxic T lymphocytes (CTLs) by dendritic cells (DCs) is crucial for elimination of pathogens and malignant cells. To activate CTLs, DCs present antigenic peptide-complexed MHC class I molecules (MHC-I) that will be recognized by the CTLs with T cell receptors and CD8 molecules. Here we show that paired Ig-like receptor (PIR)-B, an MHC-I receptor expressed on antigen-presenting cells, can regulate CTL triggering by blocking the access of CD8 molecules to MHC-I. PIR-B-deficient DCs evoked CTLs more efficiently, leading to accelerated graft and tumor rejection. PIR-B
+
non-DC transfectant cells served as less efficient stimulators and targets for CTLs than PIR-B
−
cells at the effector phase
in vitro
. On surface plasmon resonance analysis, PIR-B and CD8αα were revealed to compete in binding to MHC-I. Our results may provide a novel strategy for regulating CTL-mediated immunity and diseases in a sterical manner.
Distinct TRP channels are required for warm and cool avoidance in
Drosophila melanogaster
Authors: Rosenzweig Mark , Kang KyeongJin , Garrity Paul A.
Published: September 2008

The ability to sense and respond to subtle variations in environmental temperature is critical for animal survival. Animals avoid temperatures that are too cold or too warm and seek out temperatures favorable for their survival. At the molecular level, members of the transient receptor potential (TRP) family of cation channels contribute to thermosensory behaviors in animals from flies to humans. In
Drosophila melanogaster
larvae, avoidance of excessively warm temperatures is known to require the TRP protein dTRPA1. Whether larval avoidance of excessively cool temperatures also requires TRP channel function, and whether warm and cool avoidance use the same or distinct TRP channels has been unknown. Here we identify two TRP channels required for cool avoidance, TRPL and TRP. Although TRPL and TRP have previously characterized roles in phototransduction, their function in cool avoidance appears to be distinct, as neither photoreceptor neurons nor the phototransduction regulators NORPA and INAF are required for cool avoidance. TRPL and TRP are required for cool avoidance; however they are dispensable for warm avoidance. Furthermore, cold-activated neurons in the larvae are required for cool but not warm avoidance. Conversely, dTRPA1 is essential for warm avoidance, but not cool avoidance. Taken together, these data demonstrate that warm and cool avoidance in the
Drosophila
larva involves distinct TRP channels and circuits.
The geometric and spatial constraints of the microenvironment induce oligodendrocyte differentiation
Authors: Rosenberg Sheila S. , Kelland Eve E. , Tokar Eleonora , De La Torre Asia R. , Chan Jonah R.
Published: September 2008

The oligodendrocyte precursor cell (OPC) arises from the subventricular zone (SVZ) during early vertebrate development to migrate and proliferate along axon tracts before differentiating into the myelin-forming oligodendrocyte. We demonstrate that the spatial and temporal regulation of oligodendrocyte differentiation depends intimately on the axonal microenvironment and the density of precursor cells along a specified axonal area. Differentiation does not require dynamic axonal signaling, but instead is induced by packing constraints resulting from intercellular interactions. Schwann cells and even artificial beads bound to the axonal surface can mimic these constraints and promote differentiation. Together, these results describe the coordinately controlled biophysical interaction of oligodendrocyte precursors within an axonal niche leading to self-renewal and differentiation.
Euclid'sElements, Courtly Patronage and Princely Education
Authors: Brentjes Sonja
Published: September 2008

The Persian tradition of Euclid'sElementsis closely connected with the Arabic transmission of the work in Iran, Central Asia and India. This tradition has multiple starting points. Naīr al-Dīnūsī's Arabic edition had a profound impact, but it was one of several Arabic versions that served as the basis for Persian translations. At the institutional level both the Arabic and the Persian traditions flourished in different spaces—at the courts, in themadrasa, and in the sphere of collectors. Emphasizing the continued importance of court patronage, this paper explores the specifics of spatial and temporal coordinates in the transmission and transformation of Euclid'sElementsin Islamic Iran.
Illustrating Abu al-Wafā' Būzjānī: Flat Images, Spherical Constructions
Authors: Sarhangi Reza
Published: September 2008

This article analyzes two-dimensional images documented in the work of fourth/tenth century mathematician Abu al-Wafā' Būzjānī, which appear in his treatise, On Those Parts of Geometry Needed by Craftsmen. These images record three-dimensional tessellations of the sphere, geometric constructions, which may have served as a basis for architectural monuments and the interior design of domes in Islamic Iran. Such designs were very likely the result of collaborations among mathematicians and artists. As explained here, the construction of the icosahedron on a sphere, as presented in Būzjānī's treatise, is not mathematically correct. But the construction of the spherical dodecahedron is precise. Būzjānī's studies of the sphere as a three-dimensional form deserve further consideration as an important component in the development of mathematical thinking.
Iran's Early Encounter with Three Medieval European Inventions (875–1153 AH/1470–1740 CE)
Authors: Nourbakhsh Mohammad Reza (Farhad)
Published: September 2008

The production of the mechanical clock, the printing press, and firearms in Western Europe during the Middle Ages is considered the precursor to many subsequent technological advances. This paper briefly reviews the introduction of these inventions to Iran, and the pace of their adoption in that country. Firearms were more readily accepted, but clocks and printing took a longer time to become prevalent. This paper will also examine some of the possible explanations for the contrast between the rapid spread of clocks and printing in Western Europe and the lack of their widespread adoption in Iran. This phenomenon cannot simply be attributed to scientific and technological backwardness, nor can it have been due merely to geographic or cultural differences. This underscores the significance of the overall social and economic conditions, which are in turn explored.
Secular Sciences and the Question of “Decline”
Authors: Yousefi Najm al-Din
Published: September 2008

The fate of secular sciences in Islamic civilization has been the object of intense historical investigation. Historians have long sought to explicate the seemingly mysterious reduction of knowledge production in late medieval Islam. The present article attempts to grapple with this phenomenon by focusing on the social elements of knowledge production at the local, rather than the global level. It argues that the transmission of ancient knowledge to medieval Islam depended largely on a close cooperation among historical agents, who sought to advance various interests. The ultimate reduction of knowledge production—commonly referred to as the “decline” of sciences—was brought about by intense rivalry and the increased tension between different forms of knowledge and their representatives, which in turn hampered patterns of cooperation. The article stresses the contingent nature of the social relations that gave rise to the “decline” of sciences: the configuration of social agents, their interactions, and the final outcomes were not bound to unfold the way they did, nor did they have to follow the same path that led to emergence of modern Western science.