bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison between western Tethys and eastern Pacific ammonites: further evidence for a possible late Sinemurian–early Pliensbachian trans-Pangaean marine connection
Authors: VENTURI FEDERICO , BILOTTA MASSIMILIANO , RICCI CARLO
Published: September 2006

Comparing the Early Jurassic ammonoids found in three Italian Apennine sections (Bosso, Pallareto and Furlo) with those reported in the literature for some South American sections (Argentina and Chile), we noted that these two areas share the same late Sinemurian–early Pliensbachian faunal succession: Paltechioceras in the late Sinemurian (Raricostatum Zone), Catriceras in the earliest Pliensbachian (Jamesoni Zone, Taylori Subzone), Miltoceras in the middle part of the early Pliensbachian (Jamesoni Zone, Polymorphus Subzone). An overall similarity to Apennine and South American ammonite faunas of the same age can be found for some sections of Morocco and partially also for southern Spain. One of the Italian taxa (an unpublished early Pliensbachian Apennine genus, ascribable to the family Polymorphitidae) is reported in the South American Pacific coast by the middle to late part of the early Pliensbachian (Ibex Zone). Evolving towards more and more discoidal morphologies, it might have given rise to an endemic American ammonite group, which is represented by the genera Eoamaltheus Hillebrandt and Fanninoceras McLearn. This phylogenetic reconstruction is based on several lines of evidence (shell morphology, ontogenetic development, aspect of the suture lines, biostratigraphy), and can be safely traced back to the basal Pliensbachian strata of the Tethyan Palaeoprovince. As far as we know, the examined ammonoid taxa are exclusively found in the western Tethys (e.g. Italian Apennines) and American Pacific coast (e.g. Argentina), but they have never been recorded elsewhere, and they show no evidence of pantropical distribution. Our biostratigraphic and phylogenetic data suggest the existence of a late Sinemurian–early Pliensbachian marine connection between the western Tethys (Italian Apennines) and the South American Pacific coast (Argentina). This is the so-called Hispanic Corridor, the existence of which has already been supported by many authors using several geological and palaeontological pieces of evidence. According to our interpretation, as well as the conclusions of other workers, it was a temporary and intermittent seaway, which allowed a partial faunal exchange for some taxa (including certain shallow-water ammonoids) during Sinemurian and Pliensbachian times. This palaeobiogeographic model consistently relates the biostratigraphy and evolution of some western Tethys and South American ammonoids to the major palaeogeographic changes affecting this vast area. In any case, our working hypothesis does not have any claim of universal applicability; we deem the proto-Atlantic seaway model to be the most suitable (until proof of the contrary) for the ammonites we examined, but it may not be necessarily valid for all the currently known taxa.
JOHN DRYDEN, THE HOUSE OF ORMOND, AND THE POLITICS OF ANGLO-IRISH PATRONAGE
Authors: OHLMEYER JANE , ZWICKER STEVEN
Published: September 2006

This article analyses John Dryden's personal and textual relations with the Butlers of Ormond as they are played out over four decades in a series of texts – Absalom and Achitophel (1681), the dedication of his Life of Plutarch (1683), the engraved plates of the Aeneid (1697), and the verse which opens Fables (1700). This detailed case study uncovers the nature and complexities of literary patronage during years of rebellion, war and intense political uncertainty. It addresses issues central to restoration politics and society – lineage, legitimacy, loyalty, honour, and reputation – and suggests how these issues might be explored more fully by both historians and literary scholars.
LAW IN THE VINDICIAE, CONTRA TYRANNOS: A VINDICATION
Authors: GARNETT GEORGE
Published: September 2006

Dr Anne McLaren has disputed the interpretation of the Vindiciae, contra tyrannos (1579) as a work in which Roman and canon law were fundamental. She correctly identifies Quentin Skinner and me with this interpretation. She bases her case on two sorts of evidence: the alleged paucity of Roman law citations, as compared with scriptural ones, in the margins of the original text; and our alleged failure to appreciate the ‘context’ of the Vindiciae, which, she suggests, means how it was translated and used in England, primarily in the seventeenth century. This response argues that she has seriously underestimated the number of legal citations, ignored the use of legal material which is not cited in the margins, and failed to appreciate that Scripture is interpreted in accordance with the categories and principles of Roman and canon law. It further argues that sixteenth-century France, not seventeenth-century England, is the proper ‘context’ in which to understand the book; and that substituting her assessment of English interpretations for what the original says is illegitimate.
Suicide in Early Modern and Modern Europe
Authors: HEALY RÓISÍN
Published: September 2006

This is a review of recent English- and German-language publications on suicide, both as an act and a subject of discourse, in the early and late modern periods. It argues that, while publications on the theme have increased considerably in the past two decades, the problematic character of the evidence for suicide has led to a focus on attitudes to suicide at the expense of empirical investigations. The latter have largely confirmed the link between social isolation and suicide, posited by Durkheim, but have revealed differences in patterns across social groups. The growth of lenient attitudes to suicide has proven to be more protracted and contested than originally believed. The ambivalent role of clergy, the persistence of religious sanctions against suicide, and continued efforts by the state to curb suicide all suggest that the term ‘hybridization’ better characterizes the changes over this period than the older term ‘secularization’. Finally, this review recommends that historians undertake further empirical investigations of suicide, where possible, and that they broaden suicide research to include suicidal behaviours and alternative responses to despair in order to identify the specific allure of suicide.
QUEENSHIP IN EARLY MODERN ENGLAND AND SCOTLAND
Authors: MCLAREN ANNE
Published: September 2006

The last medieval queens: English queenship, 1445–1503. By J. L. Laynesmith. Oxford: Oxford University Press, 2004. Pp. xxviii+294. ISBN 0-19-924 737-4. £35.00.

The marrying of Anne of Cleves: royal protocol in Tudor England. By Retha M. Warnicke. Cambridge: Cambridge University Press, 2000. Pp. xiv+343. ISBN 0-521-77037-8. £19.95.

Mary of Guise in Scotland, 1548–1560: a political career. By Pamela E. Ritchie. East Lothian: Tuckwell Press, 2002. Pp. xii+306. ISBN 1-86232-184-1. £20.00.

My heart is my own: the life of Mary Queen of Scots. By John Guy. London: Fourth Estate, 2004. Pp. xii+574. ISBN 1-84115-752-X. £20.00.

Queenship in Britain, 1660–1837. Edited by Clarissa Campbell Orr. Manchester: Manchester University Press, 2002. Pp. xii+300. ISBN 0-7190-5769-8. £49.99.

Therefore if any man be in christ, let him be a new creature.Old things are passed away: behold, all things are become new.2 Cor. 5:17, Geneva Bible

The Reformation's claim to be, in Patrick Collinson's words, the ‘greatest geological fault line in European civilisation’ rests not on the fact that it proposed a new set of answers to old questions, but rather that it proposed old answers in a new world – the one that came into being with the advent of printing. This confluence transformed the ways in which the yearning for purification and renewal endemic to the religious impulse was enacted and institutionalized during the early modern period. Most radically, the Reformation challenged the socio-political hierarchies of degree, descent, and gender that had ordered medieval society. These hierarchies were most powerfully symbolized by the person of the king. In important ways they were perceived to be embodied in and dependent on him and, through him, on the women who came to be queens. To understand early modern queenship, we must bear this cultural context in mind. Too often, however, historians fail to do so, writing instead of kings and queens in terms more suited to modern political biography. This limits our ability to comprehend not only the phenomenon of kingship, but also – for as long as personal monarchy remained the dominant form of European government – political culture more generally. This review article provides an opportunity to address this historiographical deficiency. I therefore want to begin by sketching out the contours of early modern queenship, before turning my attention to the books under review.
Purification of Densonucleosis Virus by Tangential Flow Ultrafiltration
Authors: Grzenia David L. , Carlson Jonathan O. , Czermak Peter , Han Binbing , Specht Rachel K. , Wickramasinghe S. Ranil
Published: September 2006

Purification at commercial scale of viruses and virus vectors for gene therapy applications and viral vaccines is a major separations challenge. Tangential flow ultrafiltration has been developed for protein purification. Here tangential flow ultrafiltration of parvoviruses has been investigated. Because these virus particles are small (18–26 nm), removal of host cell proteins will be challenging. The results obtained here indicate that 30, 50, and 100 kDa membranes reject the virus particles, whereas 300 kDa membranes allow some virus particles to pass into the permeate. The decrease in permeate flux for the 300 kDa ultrafiltration membrane is much greater than for the 30, 50, and 100 kDa membranes, indicating possible entrapment of virus particle in the membrane pores. The permeate flux and level of protein rejection is strongly affected by the cell culture growth medium. The results indicate that when developing a new process, it is essential that the cell culture and purification operations be developed in parallel.
Estimates of flushing times, submarine groundwater discharge, and nutrient fluxes to Okatee Estuary, South Carolina
Authors: Moore Willard S. , Blanton Jackson O. , Joye Samantha B.
Published: September 2006

A physical model based on determining the fraction of the tidal prism that returns to the estuary on the next high tide is used to estimate the flushing time of the Okatee River estuary. The return flow factor (b) of 0.81 yields a flushing time of 2 days. A mass balance model of 228Ra and salinity is also used to estimate b. This model yields an average b = 0.79, virtually the same as the physical model. A third model based on the decay of 224Ra relative to 228Ra is used to determine the apparent age of water in the estuary. These ages range from 1.6 to 5 days, with an average of 3.4 days. These three independent estimates are in remarkably close agreement, certainly within the error of each estimate. We use these residence times to develop a mass balance model for the radium isotopes in the Okatee estuary. We consider decay, mixing, sedimentary input, river input, and submarine groundwater discharge (SGD). The major loss term for each isotope is mixing with water in Port Royal Sound; the major input for each isotope is SGD. At steady state these terms must balance. Knowing the water age and the radium isotope composition of groundwater entering the Okatee allows us to estimate an average SGD flux of 1 m3/s. The SGD flux is a factor of 3–4 greater during the summer relative to the winter. This SGD supplies a considerable quantity of nutrients and carbon into the Okatee system.
Impact of different initial soil moisture fields on Eta model weather forecasts for South America
Authors: de Goncalves L. Gustavo Goncalves , Shuttleworth William James , Chou Sin Chan , Xue Yongkang , Houser Paul R. , Toll David L. , Marengo José , Rodell Matthew
Published: September 2006

Two 7‐day weather simulations were made for South America in July 2003 and January 2004 (in the Southern Hemisphere summer and winter) to investigate the impacts of using different soil moisture initialization fields in the Eta model coupled to the Simplified Simple Biosphere (SSiB) land surface model. The alternative initial soil moisture fields were (1) the soil moisture climatology used operationally by the Centro de Previsão do Tempo e Estudos Climáticos in Brazil and (2) the soil moisture fields generated by a South American Land Data Assimilation System (SALDAS) based on SSiB. When the SALDAS soil moisture fields were used, there was an increase in the model performance relative to climatology in the equitable threat score calculated with respect to observed surface precipitation fields and a decrease (up to 53%) in the root‐mean‐square error relative to the NCEP analysis of the modeled geopotential height at 500 hPa and mean sea level pressure. However, there was small change in the model skill in positioning the primary South American weather systems because of a change in the upper troposphere circulation caused by SALDAS initialization, most noticeably in the South Atlantic Convergence Zone.
Continuous estimation of winter carbon dioxide efflux from the snow surface in a deciduous broadleaf forest
Authors: Suzuki Satoru , Ishizuka Shigehiro , Kitamura Kenzo , Yamanoi Katsumi , Nakai Yuichiro
Published: September 2006

The objective of our study was to estimate CO2 efflux from the snow surface in a deciduous broadleaf forest throughout the duration of winter on the basis of a continuous measurement of CO2 concentration at the soil‐snow interfaces. Continuous CO2 efflux was estimated from the CO2 concentration gradient across the snow cover. We examined the accuracy of the values obtained from the CO2 concentration gradient across the snow cover by comparing them with the values observed by the closed static chambers. Although each couple of the values from both methods had relatively large differences, the amounts of the values were consistent. The average CO2 efflux ± 1SD was 1.4 ± 1.0 gCO2 m−2 d−1 throughout the duration of winter. The estimated CO2 efflux in winter is considered to be reasonable, compared with the value obtained by a relationship between soil temperature and soil respiration in the same forest and with the values reported in forest ecosystems in middle latitudes. Our value is, however, smaller than the value obtained by the eddy covariance technique at a tower in the same forest. We attempted to estimate the hypothetical CO2 efflux, minimizing the impact of pressure pumping. The average CO2 efflux was estimated at 2.0 gCO2 m−2 d−1.
Alba Patera, Mars: Topography, structure, and evolution of a unique late Hesperian–early Amazonian shield volcano
Authors: Ivanov Mikhail A. , Head James W.
Published: September 2006

New spacecraft data, especially MOLA topography, reveal important characteristics of Alba Patera that were either unknown or poorly resolved in previous data sets. The major and consistent breaks of slope and the specific pattern of lava flows within a broad region around Alba Patera permit division of this area into two major parts that appear to be related to different episodes of volcanism at Alba Patera: a low‐lying apron of lava flows that broadly surrounds the edifice, a high‐standing main construct, consisting of a central edifice, western and eastern flanking lobes, and a summit area characterized by a summit plateau and a summit dome topped by a caldera complex. Volcanic activity apparently began as massive effusive eruptions that formed the broad apron of lava flows, followed by more focused effusive eruptions that built the central construct. The construct spread gravitationally in a northerly direction to favor E‐W dike propagation, leading to the formation of Tharsis‐Montes‐like flanking lobes. The final stages of volcanic activity at Alba Patera were concentrated in the summit area, forming a summit dome ∼400 km in diameter, a caldera complex, and two small shields near and inside the caldera, which underwent late‐stage tilting and deformation; the load of the newly documented summit dome may have led to the development of Alba Fossae, reactivation of graben within Tantalus Fossae, and tilting of the summit dome to the east. A clear sequence in eruptive style is observed (early massive sheet flows, later tube‐fed flows, and late, shorter‐length and lower‐volume sheet flows). Dendritic valley networks on the northern flanks of Alba Patera have been interpreted to be evidence of easily erodable material of pyroclastic origin, but new data suggest that these friable deposits and the valley networks may have formed instead during Amazonian climate excursion periods. The extensive apron of lava flows, combined with the flanking lava lobes and the Tharsis‐Montes‐scale summit dome, make Alba Patera much more similar to the Tharsis Montes than to the Hesperian‐aged paterae. The Alba Patera lava apron was emplaced on early Hesperian ridged plains largely during the middle to late Hesperian; stratigraphic relationships suggest that effusive eruptions from Alba Patera interacted with ice‐rich deposits in the northern lowlands. Alba Patera flanking lobes and the summit dome were emplaced in the earliest Amazonian, accompanied by late‐stage loading, graben formation, and edifice tilting.
Simulation of spontaneous and variable global dust storms with the GFDL Mars GCM
Authors: Basu Shabari , Wilson John , Richardson Mark , Ingersoll Andrew
Published: September 2006

We report on the successful simulation of global dust storms in a general circulation model. The simulated storms develop spontaneously in multiyear simulations and exhibit significant interannual variability. The simulated storms produce dramatic increases in atmospheric dustiness, global‐mean air temperatures, and atmospheric circulation intensity, in accord with observations. As with observed global storms, spontaneous initiation of storms in the model occurs in southern spring and summer, and there is significant interannual variability in storm development: years with no storms are interspersed with years with storms of various sizes and specific seasonal date of initiation. Our results support the idea that variable and spontaneous global dust storm behavior can emerge from a periodically forced system (the only forcing being the diurnal and seasonal cycles) when the dust injection mechanism involves an activation threshold. In our simulations, surface wind stresses associated with resolved, large‐scale (>300 km) wind systems initiate the storms. These winds are generally associated with the seasonally migrating CO2 cap boundary and sloping topography of the Hellas basin, thermal tides, and traveling waves. A very limited number of large storms begin with lifting along the frontal zones associated with traveling waves in the northern hemisphere. Explosive growth to global scales results from the intensification of the Hadley circulation and the activation of secondary dust‐lifting centers.
Low Earth orbit satellite navigation errors and vertical total electron content in single‐frequency GPS tracking
Authors: Garcia‐Fernàndez Miquel , Montenbruck Oliver
Published: September 2006

In the context of space applications, the GPS system is presently a well‐established and accepted tracking system. To meet the basic navigation requirements, most satellites in a low Earth orbit are equipped with single‐frequency GPS receivers that measure the coarse acquisition code as well as the L1 phase. However, the resulting kinematic navigation solutions exhibit systematic position errors caused by elevation‐dependent ionospheric path delays. In this study a simple analytical model is established, which quantitatively relates the position error to the vertical electron content and the mapping function. This model substantiates the empirical evidence of a mean radial offset that increases in proportion to the total electron content above the satellite. It is furthermore shown that the ratio between this offset and the vertical ionospheric path delay depends on the applied elevation mask angle. Representative ratios of 3–5 are obtained for the mapping function of the Lear ionosphere model and elevation cutoff angles of 10°, 5°, and 0°. This analytical result has further been confirmed by signal simulator tests as well as flight data of the CHAMP satellite.
Climate impacts of the Atlantic Multidecadal Oscillation
Authors: Knight Jeff R. , Folland Chris K. , Scaife Adam A.
Published: September 2006

The Atlantic Multidecadal Oscillation (AMO) is a near‐global scale mode of observed multidecadal climate variability with alternating warm and cool phases over large parts of the Northern Hemisphere. Many prominent examples of regional multidecadal climate variability have been related to the AMO, such as North Eastern Brazilian and African Sahel rainfall, Atlantic hurricanes and North American and European summer climate. The relative shortness of the instrumental climate record, however, limits confidence in these observationally derived relationships. Here, we seek evidence of these links in the 1400 year control simulation of the HadCM3 climate model, which produces a realistic long‐lived AMO as part of its internal climate variability. By permitting the analysis of more AMO cycles than are present in observations, we find that the model confirms the association of the AMO with almost all of the above phenomena. This has implications for the predictability of regional climate.
Is there evidence for sunspot forcing of climate at multi‐year and decadal periods?
Authors: Moore John , Grinsted Aslak , Jevrejeva Svetlana
Published: September 2006

It has been proposed that solar cycle irradiance variations may affect the whole planet's climate via the stratosphere, the Quasi‐Biennial Oscillation (QBO) and Arctic Oscillation (AO). We test this hypothesis by examining causal links between time series of sunspot number and indices of QBO, AO and ENSO activity. We use various methods: wavelet coherence, average mutual information, and mean phase coherence to study the phase dynamics of weakly interacting oscillating systems. All methods clearly show a cause and effect link between Southern Oscillation Index (SOI) and AO, but no link between AO and QBO or solar cycle over all scales from biannual to decadal. We conclude that the 11‐year cycle sometimes seen in climate proxy records is unlikely to be driven by solar forcing, and most likely reflects other natural cycles of the climate system such as the 14‐year cycle, or a harmonic combination of multi‐year cycles.
Thermal model of the Vesuvius magma chamber
Authors: de Lorenzo S. , Di Renzo V. , Civetta L. , D'Antonio M. , Gasparini P.
Published: September 2006

A thermal modeling of the Vesuvius is presented, based on its magmatic and volcanic history. A 2D numerical scheme has been developed to evaluate the heat transfer inside and around a magma body, the latent heat of crystallization and the inputs of magma from the asthenosphere to a crustal reservoir. Assuming a ratio >1 between velocities of magma ascending in the conduit and magma laterally displaced in the reservoir, the results indicate that, after 40 ka, the reservoir is vertically thermally zoned. As a consequence it hosts magma batches that can individually differentiate, mix and be contaminated by the crust, and produce the spectrum of isotopic compositions of the Vesuvian products. The thermal model reproduces the geothermal gradient and the brittle‐ductile transition (250–300°C) at 6 km of depth (the maximum depth of earthquake foci) only after 0.5–1 Ma, implying a long lived magma chamber below the volcano.
Satellite measurements of chlorophyll distribution during spring 2005 in the California Current
Authors: Thomas Andrew C. , Brickley Peter
Published: September 2006

Eight years of satellite data quantify spring 2005 surface chlorophyll‐a (chl‐a) anomalies in coastal areas of the California Current. Negative anomalies <−1.0 mg m−3 begin in March north of ∼47°N, spread south to 43°N in April and 40°N in May and June 2005, maximum (<−2.0 mg m−3) north of 45°N. Positive chlorophyll anomalies dominate from ∼40°N to 27°N during this period. Strongest negative wind stress and positive coastal surface temperature anomalies are located south of maximum chl‐a anomalies, in the region of maximum climatological summer wind stress. Despite the magnitude of these wind anomalies, they remain upwelling‐favorable and negative chl‐a anomalies are in higher latitude regions of weaker wind anomalies, sufficient however, to prolong winter downwelling, delaying the onset of spring upwelling. In June, winds across the entire region become strongly upwelling favorable and by July, chl‐a anomalies switch to positive.
Solar heating of suspended particles and the dynamics of Martian dust devils
Authors: Fuerstenau Stephen D.
Published: September 2006

The heat input to Martian dust devils due to solar warming of suspended particles is assessed based on a prior estimate of dust loading and from an analysis of shadows cast by dust devils in images taken from orbit. Estimated values for solar heating range from 0.12 to 0.57 W/m3 with associated temperature increases of 0.011 to 0.051°C per second. These warming rates are comparable to the adiabatic cooling rate expected for a gas parcel rising on Mars with a vertical velocity of 10 m/s. Solar warming of suspended dust serves to maintain buoyancy in a rising dust plume and may be one cause for the large scale of dust devils observed on Mars.
Evaluation of ERS scatterometer soil moisture products over a half‐degree region in southwestern France
Authors: Pellarin Thierry , Calvet Jean‐Christophe , Wagner Wolfgang
Published: September 2006

This paper investigates the ERS Scatterometer soil moisture products precision over a half‐degree region in Southwestern France. Based on a high resolution soil moisture simulation (1 km2) validated at the local scale, the ERS‐scat product is assessed at its own resolution (about 50 × 50 km2). The study points out the suitable quality of the surface soil moisture product (root mean square error equal to 0.06 m3.m−3 for a 4‐year period) and assesses the retrieved root‐zone soil moisture accuracy provided by a semi‐empirical methodology exclusively based on surface soil moisture products.
Importance of oceanic heat uptake in transient climate change
Authors: Stouffer Ronald J. , Russell Joellen , Spelman Michael J.
Published: September 2006

The impact of the differences in the oceanic heat uptake and storage on the transient response to changes in radiative forcing is investigated using two newly developed coupled atmosphere‐ocean models. In spite of its larger equilibrium climate sensitivity, one model (CM2.1) has smaller transient globally averaged surface air temperature (SAT) response than is found in the second model (CM2.0). The differences in the SAT response become larger as radiative forcing increases and the time scales become longer. The smaller transient SAT response in CM2.1 is due to its larger oceanic heat uptake. The heat storage differences between the two models also increase with time and larger rates of radiative forcing. The larger oceanic heat uptake in CM2.1 can be traced to differences in the Southern Ocean heat uptake and is related to a more realistic Southern Ocean simulation in the control integration.
Self-catalysis: A contamination-free, substrate-free growth mechanism for single-crystal nanowire and nanotube growth by chemical vapor deposition
Authors: Noor Mohammad S.
Published: September 2006

A unified mechanism for the growth of a wide variety of long, uniform, single-crystal nanowires and whiskers, including III–V and II–VI binary, ternary, and quaternary nanowires and whiskers, without the use of any substrate and catalyst has been presented. While elucidating the mechanism, attempts have been made to provide a kinetic and thermodynamic rationale for the growth. Various features of the growth mechanism, including the formation of liquid droplets and seeds, nucleation, and creation of products, have been discussed. Extensive studies of illustrative examples provide the validity of the proposed mechanism. The influence of various parameters such as growth temperature and chamber pressure on the growth mechanism has been studied. The advantages and disadvantages of the proposed mechanism, and its superiority to the well-known vapor-liquid-solid mechanism, have been elucidated. Means to improve the mechanism to obtain self-aligned nanowires and whiskers have been suggested. Based on these, it has been demonstrated that the present mechanism is indeed a powerful self-catalytic growth mechanism uniquely suited to the growth of a wide variety of single-crystal nanowires and whiskers. It can be very useful also for the growth of single-crystal nanotubes.
Finite element implementation of Braginskii’s gyroviscous stress with application to the gravitational instability
Authors: Ferraro N. M. , Jardin S. C.
Published: September 2006

A general coordinate-independent expression for Braginskii’s form of the ion gyroviscosity in the two-dimensional potential field representation is presented, and is implemented in a full two-dimensional, two-fluid extended magnetohydrodynamic (MHD) numerical model. The expression for the gyroviscous force requires no field to be differentiated more than twice, and thus is appropriate for finite elements with first derivatives continuous across element boundaries (C1 finite elements). From the extended MHD model, which includes the full gyroviscous stress, are derived linear dispersion relations of a homogeneous equilibrium and of an inverted-density profile in the presence of gravity. The treatment of the gravitational instability presented here extends previous work on the subject [M. N. Rosenbluth, N. A. Krall, and N. Rostoker, Nucl. Fusion Suppl. 1, 143 (1962); K. V. Roberts and J. B. Taylor, Phys. Rev. Lett. 8, 197 (1962)]. Linear and nonlinear simulations of the gravitational instability are presented. Simulations are shown to agree closely with the derived dispersion relations in the linear regime. The “gyroviscous cancellation” effect is demonstrated, and some limitations of the v⃗* approximation are discussed.
Gas-liquid phase separation in oppositely charged colloids: Stability and interfacial tension
Authors: Fortini Andrea , Hynninen Antti-Pekka , Dijkstra Marjolein
Published: September 2006

We study the phase behavior and the interfacial tension of the screened Coulomb (Yukawa) restricted primitive model (YRPM) of oppositely charged hard spheres with diameter σ using Monte Carlo simulations. We determine the gas-liquid and gas-solid phase transitions using free energy calculations and grand-canonical Monte Carlo simulations for varying inverse Debye screening length κ. We find that the gas-liquid phase separation is stable for κσ⩽4, and that the critical temperature decreases upon increasing the screening of the interaction (decreasing the range of the interaction). In addition, we determine the gas-liquid interfacial tension using grand-canonical Monte Carlo simulations. The interfacial tension decreases upon increasing the range of the interaction. In particular, we find that simple scaling can be used to relate the interfacial tension of the YRPM to that of the restricted primitive model, where particles interact with bare Coulomb interactions.
D
matrix analysis of the Renner-Teller effect: An accurate three-state diabatization for NH2
Authors: Halász G. J. , Vibók Á. , Baer R. , Baer M.
Published: September 2006

Some time ago we published our first article on the Renner-Teller (RT) model to treat the electronic interaction for a triatomic molecule [J. Chem. Phys. 124, 081106 (2006)]. The main purpose of that Communication was to suggest considering the RT phenomenon as a topological effect, just like the Jahn-Teller phenomenon. However, whereas in the first publication we just summarized a few basic features to support that idea, here in the present article, we extend the topological approach and show that all the expected features that characterize a three (multi) state RT-type'3 system of a triatomic molecule can be studied and analyzed within the framework of that approach. This, among other things, enables us to employ the topological D matrix [Phys. Rev. A 62, 032506 (2000)] to determine, a priori, under what conditions a three-state system can be diabatized. The theoretical presentation is accompanied by a detailed numerical study as carried out for the HNH system. The D-matrix analysis shows that the two original electronic states A12 and B12 (evolving from the collinear degenerate Π doublet), frequently used to study this Renner-Teller-type system, are insufficient for diabatization. This is true, in particular, for the stable ground-state configurations of the HNH molecule. However, by including just one additional electronic state—a B state (originating from a collinear Σ state)—it is found that a rigorous, meaningful three-state diabatization can be carried out for large regions of configuration space, particularly for those, near the stable configuration of NH2. This opens the way for an accurate study of this important molecule even where the electronic angular momentum deviates significantly from an integer value.
m
=
1
ideal internal kink modes in a line-tied screw pinch
Authors: Huang Yi-Min , Zweibel Ellen G. , Sovinec Carl R.
Published: September 2006

It is well known that the radial displacement of the m=1 internal kink mode in a periodic screw pinch has a steep jump at the resonant surface where k∙B=0 [Rosenbluth, Dagazian, and Rutherford, Phys. Fluids 16, 1894 (1973)]. In a line-tied system, relevant to solar and astrophysical plasmas, the resonant surface is no longer a valid concept. It is then of interest to see how line-tying alters the aforementioned result for a periodic system. If the line-tied kink also produces a steep gradient, corresponding to a thin current layer, it may lead to strong resistive effects even with weak dissipation. Numerical solution of the eigenmode equations shows that the fastest growing kink mode in a line-tied system still possesses a jump in the radial displacement at the location coincident with the resonant surface of the fastest growing mode in the periodic counterpart. However, line-tying thickens the inner layer and slows down the growth rate. As the system length L approaches infinity, both the inner layer thickness and the growth rate approach the periodic values. In the limit of small ϵ∼Bϕ∕Bz, the critical length for instability Lc∼ϵ−3. The relative increase in the inner layer thickness due to line-tying scales as ϵ−1(Lc∕L)2.5.
Electromagnetic and gravitational interactions of the spinning particle
Authors: Ünal Nuri
Published: September 2006

We consider the invariance of the spinning free particle Lagrangian under the global coordinate transformations for the classical model of the electron with internal degrees of freedom and obtain the conservation of the energy-momentum, total angular momentum, and electric charge. The local gauge transformations give the electromagnetic and gravitational interactions of the spinning particle in the Riemann-Cartan space from the generalized spin connections. We show that the covariant constancy of the Dirac matrices gives; (i) the form invariance of the classical equations of motion, except the gravitational force terms in nongeodesic equation, (ii) the conservation of the electromagnetic current, (iii) the quantum Hamiltonian and equations of motion from the classical ones without the quantum ordering corrections, and (iv) the minimal coupling of the gravitation with the spinning particle in the Hamiltonian and in wave equations in the Riemann-Cartan space–time.
Growth and decomposition of aligned and ordered PdO nanoparticles
Authors: Penner Simon , Wang Di , Jenewein Bernd , Gabasch Harald , Klötzer Bernhard , Knop-Gericke Axel , Schlögl Robert , Hayek Konrad
Published: September 2006

The formation, thermal decomposition, and reduction of small PdO particles were studied by high-resolution transmission electron microscopy and selected area electron diffraction. Well-defined Pd particles (mean size of 5–7nm) were grown epitaxially on NaCl (001) surfaces and subsequently covered by a layer of amorphous SiO2 (25nm), prepared by reactive deposition of SiO in 10−2Pa O2. The resulting films were exposed to molecular O2 in the temperature range of 373–673K, and the growth of PdO was studied. The formation of a PdO phase starts at 623K and is almost completed at 673K. The high-resolution experiments suggest a topotactic growth of PdO crystallites on top of the original Pd particles. Subsequent reaction of the PdO in 10mbar CO for 15min and thermal decomposition in 1bar He for 1h were also investigated in the temperature range from 373to573K. Reductive treatments in CO up to 493K do not cause a significant change in the PdO structure. The reduction of PdO starts at 503K and is completed at 523K. In contrast, PdO decomposes in 1bar He at around 573K. The mechanism of PdO growth and decay is discussed and compared to results of previous studies on other metals, e.g., on rhodium.
Electron stimulated desorption of anionic fragments from films of pure and electron-irradiated thiophene
Authors: Hedhili M. N. , Cloutier P. , Bass A. D. , Madey T. E. , Sanche L.
Published: September 2006

The electron stimulated desorption (ESD) of anions is used to explore the effects of electron irradiation on a thiophene film and we report measurements for electron impact on multilayer thiophene condensed on a polycrystalline platinum substrate. Below 22eV and at low electron dose, desorbed anions include H− (the dominant signal) as well as S−, CH2−, SH− and SCH2−. Yield functions show that anions are desorbed both by dissociative electron attachment (DEA) with resonances observed at 9.5, 11, and 16eV, and for energies >13eV, by dipolar dissociation (DD). An increase in the S− signal from electron irradiated (beam-damaged) thiophene films and the appearance of a new DEA resonance in the S− yield function at 6eV are linked to rupture of the thiophene ring and the formation of sulfur-terminated products within the film. The threshold energy for ring rupture is 5eV. The desorption of new anions such as C4H3S− (Thiophene-H)−is also observed from electron irradiated films and these likely arise from the decomposition of large radiation product molecules synthesized in the film. The yield functions of H−, S−, SH−, (Thiophene-H)−, and (Thiophene+H)− anions from irradiated thiophene films that have been annealed to 300K, each exhibit a single resonant feature centered around 5.1eV, suggesting that all signals derive from DEA to the same molecular radiation product. In contrast, only H− and S− are observed to desorb from films of 2-2-bithiophene and no resonance is seen below ∼10eV in the anion yield functions. These data suggest that electron irradiation causes formation of ring-opened oligomers, and that closed-ring or ‘classical” oligomers, (similar to bithiophene) if formed, contribute little to the ESD of anions.
A comparison of linear and nonlinear correlation factors for basis set limit Møller-Plesset second order binding energies and structures of He2, Be2, and Ne2
Authors: Tew David P. , Klopper Wim
Published: September 2006

The basis set limit Møller-Plesset second-order equilibrium bond lengths of He2, Be2, and Ne2, accurate to 0.01a0, are computed to be 5.785a0, 5.11a0, and 6.05a0. The corresponding binding energies are 22.4±0.1, 2180±20, and 86±2μEh, respectively. An accuracy of 95% in the binding energy requires an aug-cc-pV6Z basis or larger for conventional Møller-Plesset theory. This accuracy is obtained using an aug-cc-pV5Z basis if geminal basis functions with a linear correlation factor are included and with an aug-cc-pVQZ basis if the linear correlation factor is replaced by exp(−γr12) with γ=1. The correlation factor r12exp(−γr12) does not perform as well, describing the atom more efficiently than the dimer. The geminal functions supplement the orbital basis in the description of both the short-range correlation, at electron coalescence, and the long-range dispersion correlation and the values of γ that give the best binding energies are smaller than those that are optimum for the atom or the dimer. It is important to sufficiently reduce the error due to the resolution of the identity approximation for the three- and four-electron integrals and we recommend the complementary auxiliary basis set method. The effect of both orbital and geminal basis set superposition error must be considered to obtain accurate binding energies with small orbital basis sets. In this respect, we recommend using exp(−γr12) with localized orbitals and the original orbital-variant formalism.
Glass transition in pure and doped amorphous solid water: An ultrafast microcalorimetry study
Authors: Chonde M. , Brindza M. , Sadtchenko Vlad
Published: September 2006

Using an ultrafast scanning microcalorimetry apparatus capable of heating rates in excess of 105K∕s, we have conducted the first direct measurements of thermodynamic properties of pure and doped amorphous solid water (also referred to as low density amorphous ice) in the temperature range from 120to230K. Ultrafast microcalorimetry experiments show that the heat capacity of pure amorphous solid water (ASW) remains indistinguishable from that of crystalline ice during rapid heating up to a temperature of 205±5K where the ASW undergoes rapid crystallization. Based on these observations, we conclude that the enthalpy relaxation time in pure ASW must be greater than 10−5s at 205K. We argue that this result contradicts the assignment of glass transition temperature to 135K and that ASW may undergo fragile to strong transition at temperatures greater than 205K. Unlike pure ASW, we observe an approximately twofold rise in heat capacity of CH3COOH doped ASW at 177±5K. We discuss results of past studies taking into account possible influence of impurities and confinement on physical properties of ASW.
Virial coefficients and osmotic pressure in polymer solutions in good-solvent conditions
Authors: Caracciolo Sergio , Mognetti Bortolo Matteo , Pelissetto Andrea
Published: September 2006

We determine the second, third, and fourth virial coefficients appearing in the density expansion of the osmotic pressure Π of a monodisperse polymer solution in good-solvent conditions. Using the expected large-concentration behavior, we extrapolate the low-density expansion outside the dilute regime, obtaining the osmotic pressure for any concentration in the semidilute region. Comparison with field-theoretical predictions and experimental data shows that the obtained expression is quite accurate. The error is approximately 1%–2% below the overlap concentration and rises at most to 5%–10% in the limit of very large polymer concentrations.
Polymer size in dilute solutions in the good-solvent regime
Authors: Caracciolo Sergio , Mognetti Bortolo Matteo , Pelissetto Andrea
Published: September 2006

We determine the density expansion of the radius of gyration, of the hydrodynamic radius, and of the end-to-end distance for a monodisperse polymer solution in good-solvent conditions. We consider the scaling limit (large degree of polymerization), including the leading scaling corrections. Using the expected large-concentration behavior, we extrapolate these low-density expansions outside the dilute regime, obtaining a prediction for the radii for any concentration in the semidilute region. For the radius of gyration, comparison with field-theoretical predictions shows that the relative error should be at most 5% in the limit of very large polymer concentrations.
Multireference configuration interaction studies on the ground and excited states of N2O2: The potential energy curves of N2O2 along N–N distance
Authors: Li Yumin , Vo Christopher K.
Published: September 2006

In this paper, the ground and excited states of N2O2 were studied at the multireference configuration interaction (MRCI) level of theory with Dunning's [J. Chem. Phys. 90, 1007 (1985); 96, 6796 (1992)] correlation consistent basis sets augo-cc-pVDZ and aug-cc-pVTZ. The geometry optimizations were performed for the ground state of N2O2. The vertical excitation energies and transition moments were calculated for the low-lying singlet states of N2O2 including the lowest three A11 states, two B11 states, one B21 state, and two A21 states at the MRCI level of theory with Dunning’s correlation consistent basis sets aug-cc-pVDZ, aug-cc-pVTZ, and aug-cc-pVQZ. Furthermore, for the first time, the potential energy curves were calculated at the complete active space self-consistent-field and MRCI levels of theory for as many as 12 N2O2 singlet electronic states along the N–N distance. The dissociation asymptotes of these 12 N2O2 singlet electronic states were discussed.
N doping of TiO2(110): Photoemission and density-functional studies
Authors: Nambu A. , Graciani J. , Rodriguez J. A. , Wu Q. , Fujita E. , Fdez Sanz J.
Published: September 2006

The electronic properties of N-doped rutile TiO2(110) have been investigated using synchrotron-based photoemission and density-functional calculations. The doping via N2+ ion bombardment leads to the implantation of N atoms (∼5% saturation concentration) that coexist with O vacancies. Ti 2p core level spectra show the formation of Ti3+ and a second partially reduced Ti species with oxidation states between +4 and +3. The valence region of the TiO2−xNy(110) systems exhibits a broad peak for Ti3+ near the Fermi level and N-induced features above the O 2p valence band that shift the edge up by ∼0.5eV. The magnitude of this shift is consistent with the “redshift” observed in the ultraviolet spectrum of N-doped TiO2. The experimental and theoretical results show the existence of attractive interactions between the dopant and O vacancies. First, the presence of N embedded in the surface layer reduces the formation energy of O vacancies. Second, the existence of O vacancies stabilizes the N impurities with respect to N2(g) formation. When oxygen vacancies and N impurities are together there is an electron transfer from the higher energy 3d band of Ti3+ to the lower energy 2p band of the N2− impurities.
Isotope effects in the CO dimer: Millimeter wave spectrum and rovibrational calculations of (C12O18)2
Authors: Surin L. A. , Fourzikov D. N. , Giesen T. F. , Schlemmer S. , Winnewisser G. , Panfilov V. A. , Dumesh B. S. , Vissers G. W. M. , van der Avoird A.
Published: September 2006

The millimeter wave spectrum of the isotopically substituted CO dimer, (C12O18)2, was studied with the Orotron jet spectrometer, confirming and extending a previous infrared study [A. R. W. McKellar, J. Mol. Spectrosc. 226, 190 (2004)]. A very dilute gas mixture of CO in Ne was used, which resulted in small consumption of C12O18 sample gas and produced cold and simple spectra. Using the technique of combination differences together with the data from the infrared work, six transitions in the 84–127GHz region have been assigned. They belong to two branches, which connect four low levels of A+ symmetry to three previously unknown levels of A− symmetry. The discovery of the lowest state of A− symmetry, which corresponds to the projection K=0 of the total angular momentum J onto the intermolecular axis, identifies the geared bending mode of the C12O18 dimer at 3.607cm−1. Accompanying rovibrational calculations using a recently developed hybrid potential from ab initio coupled cluster [CCSD(T)] and symmetry-adapted perturbation theory calculations [G. W. M. Vissers et al., J. Chem. Phys. 122, 054306 (2005)] gave very good agreement with experiment. The isotopic dependence of the A+∕A− energy splitting, the intermolecular separation R, and the energy difference of two ground state isomers, which change significantly when O18 or C13 are substituted into the normal (C12O16)2 isotopolog [L. A. Surin et al., J. Mol. Spectrosc. 223, 132 (2004)], was explained by these calculations. It turns out that the change in anisotropy of the intermolecular potential with respect to the shifted monomer centers of mass is particularly significant.