bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction Grammar in the twenty-first century
Authors: BOAS HANS C.
Published: November 2007

Adele Goldberg, Constructions at work: The nature of generalization in language. Oxford: Oxford University Press, 2006. vii + 280.

Goldberg's new work ‘investigates the nature of our knowledge of language, how that knowledge is acquired by children, and how crosslinguistic and language-internal generalizations can be explained’. It builds on earlier research on Construction Grammar (CxG) by Fillmore (1986), Lakoff (1987), Fillmore, Kay & O'Connor (1988), and Goldberg (1995), among others. Since the mid-1990s constructions have become more and more popular as an alternative to Chomsky's (1995) Minimalist Program, but it was not until the new millennium that CxG reached a new level of interest that resulted in an ever-growing body of research (for an overview, see Fried & Östman 2004). Besides numerous articles and monographs, the increased interest in CxG is evidenced by a book series and an e-journal devoted to constructional research, as well as the bi-annual International Conference on Construction Grammar (ICCG). The publication of Goldberg (1995) inspired much constructional research over the past decade, most notably Croft's (2001) typologically oriented approach to CxG and Tomasello's (2003) constructional account of language acquisition.
Richard Hogg, 20 May 1944 – 6 September 2007
Authors: Denison David , Aarts Bas
Published: November 2007

It is with great sadness that we inform our readers of the death of Richard Hogg at the age of just sixty-three. He had been one of the three founding editors of English Language and Linguistics and was set to continue in the role until his retirement in 2009. His death has come as a great shock. We wish to share with readers of ELL at this earliest opportunity our appreciation of, and affection for, our fellow-editor, colleague and friend.
Kinship Trouble: Antigone's Claim and the Politics of Heteronormativity
Authors: Carver Terrell , Chambers Samuel A.
Published: November 2007

Heteronormativity has recently emerged as a fully shaped and well theorized concept in numerous fields, and it proves central to sexual politics and the politics of sexuality. In Antigone's Claim (2000), Judith Butler explores the heteronormativity of kinship as structured by the state, and she links this language of kinship to the incest taboo. This article focuses on Butler's politicization of kinship structures in her reading of the figure of Antigone. Because she sees the incest taboo as a social force that maintains heteronormativity by producing a particular configuration of the family, Butler advances the critique of heteronormativity. She does this through both her introduction and explication of the concept of (un)intelligibility and her explicit attention to the “incest born” person. The unintelligibility of the incest-born demands a thoroughgoing reconsideration of the liberal framework of tolerance: The unintelligible cannot be tolerated because they have not even been granted access to the category of the human. By asking us to reconsider kinship outside the defining and dominant terms of heteronormativity and the incest taboo, Butler promotes a distinct conception of politics. She thereby makes a noteworthy contribution to the political project of undoing gender hierarchy.
State Feminism since the 1980s: From Loose Notion to Operationalized Concept
Authors: Mazur Amy G. , McBride Dorothy E.
Published: November 2007

We argue that since the term state feminism first appeared in the 1980s, it has gone through three stages of development, becoming a formal concept useful in cross-national analysis in the last stage. Scholars first used the term loosely to describe a range of state activities with a gender/women's issues focus. Next, the concept became associated with the study of women's policy agencies. Most recently, a group of comparative gender and policy scholars—the Research Network on Gender Politics and the State (RNGS)—has developed systematic nominal and operational definitions of state feminism to study if, how, and why women's policy agencies make alliances with women's movements within the state to achieve feminist outcomes.
Humanity amid conflict, terror and catastrophe: hypothetical but possible scenarios
Authors: Sanyasi Anthea
Published: November 2007

This article offers an understanding of the nature, scale and complexity of two hypothetical yet possible events and their potentially overwhelming impact upon health, security and socioeconomic productivity. It describes a no-warning CBRNE incident and a gradual rising-tide emergency with a newly emerging infectious disease, summarizing a range of likely response actions, impacts and constraints, particularly for the humanitarian community.
Prompt and utter destruction: the Nagasaki disaster and the initial medical relief
Authors: Margaret Kosuge Nobuko
Published: November 2007

The article takes an overall look at the initial medical relief activities in Nagasaki after the atomic bomb fell there on 9 August 1945. In Nagasaki, as in Hiroshima, medical facilities were instantaneously destroyed by the explosion, yet the surviving doctors and other medical staff, though themselves sometimes seriously injured, did their best to help the victims. Medical facilities in adjacent areas also tended to the wounded continuously being brought there; some relief workers arrived at the disaster area when the level of radiation was still dangerously high. This article will in particular highlight the work of the doctors.
Tides and the flow of Rutford Ice Stream, West Antarctica
Authors: Gudmundsson G. Hilmar
Published: November 2007

Surface speeds of Rutford Ice Stream, West Antarctica, are known to vary by around 10–20% (depending on location) with a fortnightly periodicity corresponding to a spring‐neap tidal cycle. The reasons for these periodic variations in flow are unclear. Here the possible role of tidal stress transmission upstream of the grounding line in affecting rates of basal motion is investigated. It is found that nonlinear rheological effects within the till, when coupled with transmission of tidal stresses within the ice that are linearly related to tidal amplitude, can give rise to the type of periodic oscillations in flow observed. This nonlinear interaction between tidal forcing and till deformation increases the mean ice flux across the grounding line by a few percent above what might be expected in the absence of tidal forcing. Periodic velocity fluctuations of this type have not been observed on other ice streams. However, modeling suggests that this may be due to lack of data and that such flow variations are likely to be common features of active ice streams draining into the Ronne Ice Shelf, as well as of other ice streams subjected to similar tidal forcing.
Branch prediction and speculative execution: A magnetospheric data assimilation scheme for space weather forecasting
Authors: Doxas I. , Horton W. , Lyon J. , Wiltberger M. , Weigel R. S.
Published: November 2007

Although space weather is modeled after tropospheric weather, both in its conception as a weather system and in our efforts to forecast it, no capability exists today for assimilating magnetospheric data into space weather simulations. In this paper a scheme is proposed for assimilating magnetospheric data into a global MHD code. The scheme is similar to ensemble Kalman filters, but it is less reliant on dense data coverage and allows numerical models easier adherence to conservation laws. Three different estimates of the computational cost of the proposed scheme indicate that it is easily achievable with current computational resources.
Composition changes during disturbed conditions: Are mass spectrometers overestimating the concentrations of atomic oxygen?
Authors: Russell A. T. , St.‐Maurice J.‐P. , Sica R. J. , Noël J.‐M.
Published: November 2007

Mass spectrometer measurements during disturbed conditions have shown that heavier gases like N2 and Ar can be substantially enhanced while lighter gases like He can suffer moderate to severe depletions. Quantifying the changes in atomic and molecular oxygen is usually much more difficult as most mass spectrometers are not able to distinguish between ambient molecular oxygen and the molecular oxygen created by atomic oxygen‐satellite surface reactions, but the paucity of molecular oxygen above 250 km normally allows one to attribute any molecular oxygen above 250 km to the recombination of atomic oxygen on a satellite surface. High resolution simulations presented in this study suggest that large amounts of molecular oxygen can be transported upwards by vertical winds during geomagnetic storms and that the neglect of this effect could mean that mass spectrometers are overestimating the concentrations of atomic oxygen. These overestimations can be quite significant; a mass spectrometer inferred atomic oxygen depletion of 50% at 280 km could mean that the atomic oxygen number densities are actually one‐seventh of their quiet‐time values while the simulated molecular oxygen concentrations are 25 times greater.
Upscaling river networks for use in climate models
Authors: Arora Vivek K. , Harrison Stephen
Published: November 2007

Upscaling fine resolution river networks in a realistic manner is a cumbersome process and manual corrections are difficult to avoid. A modified algorithm is presented that offers improvement over the existing approaches and requires comparatively fewer manual corrections. The algorithm uses fine resolution flow directions to find the adjacent coarse resolution grid cell in which the majority of water drains and then corrects for increased occurrences of river flow through the sides of the grid cells. Visual comparison remains an acceptable way to assess the success of various upscaling algorithms given the complex nature of rivers and in the absence of a method for comprehensive quantitative comparison. Here, the fraction of ordinal river flow directions (a measure of side‐to‐corner preference) and the fraction of grid cells that only drain themselves (a measure of connectivity of low order river segments) are used to provide information about the nature of upscaled coarse resolution river networks in comparison to the fine resolution networks. For both visual evaluation and these more quantitative measures, the modified algorithm presented here yields the best comparison with the 0.5° resolution river networks on which the upscaled coarse resolution networks are based.
Urban photochemistry in central Tokyo: 1. Observed and modeled OH and HO2 radical concentrations during the winter and summer of 2004
Authors: Kanaya Yugo , Cao Renqiu , Akimoto Hajime , Fukuda Masato , Komazaki Yuichi , Yokouchi Yoko , Koike Makoto , Tanimoto Hiroshi , Takegawa Nobuyuki , Kondo Yutaka
Published: November 2007

We used laser‐induced fluorescence to measure the concentrations of OH and HO2 radicals in central Tokyo during two intensive campaigns (IMPACT IV and IMPACT L) in January–February and July–August 2004. The estimated detection limit for the 10‐min data was 1.3 × 105 cm−3 for the nighttime and 5.2 × 105 cm−3 for the daytime. The median values of the daytime peak concentrations of HO2 were 1.1 and 5.7 pptv for the winter and summer periods, respectively, while the values for OH were 1.5 × 106 and 6.3 × 106 cm−3. High HO2 mixing ratios (>50 pptv) were observed on a day in summer when O3 mixing ratios exceeded 100 ppbv. The average nighttime concentrations of HO2 were 0.7 and 2.6 pptv for the winter and summer periods, respectively, while the values for OH were 1.8 × 105 and 3.7 × 105 cm−3. A photochemical box model constrained by ancillary observations was able to reproduce daytime OH concentrations reasonably well for both periods, although daytime HO2 concentrations were underestimated in winter and overestimated in summer. Increasing the wintertime hydrocarbon concentrations in the model led to an increase in daytime HO2 concentrations, thereby showing better agreement with observations; however, the model continued to underestimate HO2 concentrations at high NO mixing ratios. This underestimate was most pronounced in the mornings of both periods and during the daytime in winter. We studied processes that are capable of explaining this discrepancy, including unknown reactions of HNO4 or an unidentified HOx source that is linearly scalable to the NO mixing ratio. The important processes in terms of producing radicals were the olefin + O3 reactions in the nighttime of both periods and during the daytime in winter, the photolysis of carbonyls in the daytime for both periods, and the photolysis of HONO during the daytime in winter (using measured HONO concentrations) and during mornings in summer (using estimated HONO concentrations).
MRI of Monocyte Infiltration in an Animal Model of Neuroinflammation Using SPIO-Labeled Monocytes or Free USPIO
Authors: Oude Engberink Raoul D , Blezer Erwin L A , Hoff Erik I , van der Pol Susanne M A , van der Toorn Annette , Dijkhuizen Rick M , de Vries Helga E
Published: November 2007

Magnetic resonance imaging (MRI) has been applied to visualize monocyte infiltration with the use of intravenously injected ultrasmall superparamagnetic iron oxide (USPIO). However, USPIO uptake in vivo remains elusive, and the heterogeneous enhancement patterns observed by MRI point to multiple pathophysiological events. This study focused on specific imaging of monocyte infiltration into the brain by transfusion of superparamagnetic iron oxide (SPIO)-labeled monocytes in a rat model of neuroinflammation, experimentally induced photothrombosis (PT). At day 5 after lesion induction, animals were transfused with SPIO-labeled monocytes (5 × 106 cells) or free USPIO (17 mg Fe/kg). MRI was performed 24, 72 and, 120 h later. To investigate temporal changes directly after intravenous USPIO administration, MRI was performed repeatedly up to 8 h. Relaxation measurements showed that rat monocytes were efficiently labeled in vitro using SPIO ( R2=12±0.9 s−1). After transfusion of SPIO-labeled monocytes, a significant increase in contrast enhanced area (340%±106%) in the PT lesion was observed not before 72 h. Contrast enhancement after USPIO injection increased up to 407%±39% at a much earlier point of time (24 h) and diminished thereafter. Repetitive MRI directly after USPIO injection showed significant contrast enhancement in the lesion within 2 h. Our study shows that MRI enables in vivo tracking of SPIO-labeled monocytes longitudinally. Moreover, our data suggest that contrast enhancement after injection of free USPIO does not primarily represent signals from peripherally labeled monocytes that migrated toward the inflammatory lesion. The use of SPIO-labeled monocytes provides a better tool to specifically assess the time window of monocyte infiltration.
CTCF mediates insulator function at the CFTR locus
Authors: Blackledge Neil P. , Carter Emma J. , Evans Joanne R. , Lawson Victoria , Rowntree Rebecca K. , Harris Ann
Published: November 2007

Regulatory elements that lie outside the basal promoter of a gene may be revealed by local changes in chromatin structure and histone modifications. The promoter of the CFTR (cystic fibrosis transmembrane conductance regulator) gene is not responsible for its complex pattern of expression. To identify important regulatory elements for CFTR we have previously mapped DHS (DNase I-hypersensitive sites) across 400 kb spanning the locus. Of particular interest were two DHS that flank the CFTR gene, upstream at −20.9 kb with respect to the translational start site, and downstream at +15.6 kb. In the present study we show that these two DHS possess enhancer-blocking activity and bind proteins that are characteristic of known insulator elements. The DHS core at −20.9 kb binds CTCF (CCCTC-binding factor) both in vitro and in vivo; however, the +15.6 kb core appears to bind other factors. Histone-modification analysis across the CFTR locus highlights structural differences between the −20.9 kb and +15.6 kb DHS, further suggesting that these two insulator elements may operate by distinct mechanisms. We propose that these two DHS mark the boundaries of the CFTR gene functional unit and establish a chromatin domain within which the complex profile of CFTR expression is maintained.
Sialidase NEU3 is a peripheral membrane protein localized on the cell surface and in endosomal structures
Authors: Zanchetti Gabriele , Colombi Paolo , Manzoni Marta , Anastasia Luigi , Caimi Luigi , Borsani Giuseppe , Venerando Bruno , Tettamanti Guido , Preti Augusto , Monti Eugenio , Bresciani Roberto
Published: November 2007

Sialidase NEU3 is also known as the plasma-membrane-associated form of mammalian sialidases, exhibiting a high substrate specificity towards gangliosides. In this respect, sialidase NEU3 modulates cell-surface biological events and plays a pivotal role in different cellular processes, including cell adhesion, recognition and differentiation. At the moment, no detailed studies concerning the subcellular localization of NEU3 are available, and the mechanism of its association with cellular membranes is still unknown. In the present study, we have demonstrated that sialidase NEU3, besides its localization at the plasma membrane, is present in intracellular structures at least partially represented by a subset of the endosomal compartment. Moreover, we have shown that NEU3 present at the plasma membrane is internalized and locates then to the recycling endosomal compartment. The enzyme is associated with the outer leaflet of the plasma membrane, as shown by selective cell-surface protein biotinylation. This evidence is in agreement with the ability of NEU3 to degrade gangliosides inserted into the plasma membrane of adjacent cells. Moreover, the mechanism of the protein association with the lipid bilayer was elucidated by carbonate extraction. Under these experimental conditions, we have succeeded in solubilizing NEU3, thus demonstrating that the enzyme is a peripheral membrane protein. In addition, Triton X-114 phase separation demonstrates further the hydrophilic nature of the protein. Overall, these results provide important information about the biology of NEU3, the most studied member of the mammalian sialidase family.
A stress-induced rice (Oryza sativa L.) β-glucosidase represents a new subfamily of glycosyl hydrolase family 5 containing a fascin-like domain
Authors: Opassiri Rodjana , Pomthong Busarakum , Akiyama Takashi , Nakphaichit Massalin , Onkoksoong Tassanee , Ketudat Cairns Mariena , Ketudat Cairns James R.
Published: November 2007

GH5BG, the cDNA for a stress-induced GH5 (glycosyl hydrolase family 5) β-glucosidase, was cloned from rice (Oryza sativa L.) seedlings. The GH5BG cDNA encodes a 510-amino-acid precursor protein that comprises 19 amino acids of prepeptide and 491 amino acids of mature protein. The protein was predicted to be extracellular. The mature protein is a member of a plant-specific subgroup of the GH5 exoglucanase subfamily that contains two major domains, a β-1,3-exoglucanase-like domain and a fascin-like domain that is not commonly found in plant enzymes. The GH5BG mRNA is highly expressed in the shoot during germination and in leaf sheaths of mature plants. The GH5BG was up-regulated in response to salt stress, submergence stress, methyl jasmonate and abscisic acid in rice seedlings. A GUS (glucuronidase) reporter tagged at the C-terminus of GH5BG was found to be secreted to the apoplast when expressed in onion (Allium cepa) cells. A thioredoxin fusion protein produced from the GH5BG cDNA in Escherichia coli hydrolysed various pNP (p-nitrophenyl) glycosides, including β-D-glucoside, α-L-arabinoside, β-D-fucoside, β-D-galactoside, β-D-xyloside and β-D-cellobioside, as well as β-(1,4)-linked glucose oligosaccharides and β-(1,3)-linked disaccharide (laminaribiose). The catalytic efficiency (kcat/Km) for hydrolysis of β-(1,4)-linked oligosaccharides by the enzyme remained constant as the DP (degree of polymerization) increased from 3 to 5. This substrate specificity is significantly different from fungal GH5 exoglucanases, such as the exo-β-(1,3)-glucanase of the yeast Candida albicans, which may correlate with a marked reduction in a loop that makes up the active-site wall in the Candida enzyme.
The NHB1 (N-terminal homology box 1) sequence in transcription factor Nrf1 is required to anchor it to the endoplasmic reticulum and also to enable its asparagine-glycosylation
Authors: Zhang Yiguo , Lucocq John M. , Yamamoto Masayuki , Hayes John D.
Published: November 2007

Nrf1 (nuclear factor-erythroid 2 p45 subunit-related factor 1) is negatively controlled by its NTD (N-terminal domain) that lies between amino acids 1 and 124. This domain contains a leucine-rich sequence, called NHB1 (N-terminal homology box 1; residues 11–30), which tethers Nrf1 to the ER (endoplasmic reticulum). Electrophoresis resolved Nrf1 into two major bands of approx. 95 and 120 kDa. The 120-kDa Nrf1 form represents a glycosylated protein that was present exclusively in the ER and was converted into a substantially smaller polypeptide upon digestion with either peptide:N-glycosidase F or endoglycosidase H. By contrast, the 95-kDa Nrf1 form did not appear to be glycosylated and was present primarily in the nucleus. NHB1 and its adjacent residues conform to the classic tripartite signal peptide sequence, comprising n-, h- and c-regions. The h-region (residues 11–22), but neither the n-region (residues 1–10) nor the c-region (residues 23–30), is required to direct Nrf1 to the ER. Targeting Nrf1 to the ER is necessary to generate the 120-kDa glycosylated protein. The n-region and c-region are required for correct membrane orientation of Nrf1, as deletion of residues 2–10 or 23–30 greatly increased its association with the ER and the extent to which it was glycosylated. The NHB1 does not contain a signal peptidase cleavage site, indicating that it serves as an ER anchor sequence. Wild-type Nrf1 is glycosylated through its Asn/Ser/Thr-rich domain, between amino acids 296 and 403, and this modification was not observed in an Nrf1Δ299–400 mutant. Glycosylation of Nrf1 was not necessary to retain it in the ER.
A structural basis for differential cell signalling by PAI-1 and PAI-2 in breast cancer cells
Authors: Croucher David R. , Saunders Darren N. , Stillfried Gillian E. , Ranson Marie
Published: November 2007

PAI-1 and PAI-2 (plasminogen-activator inibitor types 1 and 2) are inhibitors of cell surface uPA (urokinase plasminogen activator). However, tumour expression of PAI-1 and PAI-2 correlates with poor compared with good patient prognosis in breast cancer respectively. This biological divergence may be related to additional functional roles of PAI-1. For example, the inhibition of uPA by PAI-1 reveals a cryptic high-affinity site within the PAI-1 moiety for the VLDLr (very-low-density-lipoprotein receptor), which sustains cell signalling events initiated by binding of uPA to its receptor. These interactions and subsequent signalling events promote proliferation of breast cancer cells. Biochemical and structural analyses show that, unlike PAI-1, the PAI-2 moiety of uPA–PAI-2 does not contain a high-affinity-binding site for VLDLr, although uPA–PAI-2 is still efficiently endocytosed via this receptor in breast cancer cells. Furthermore, global protein tyrosine phosphorylation events were not sustained by uPA–PAI-2 and cell proliferation was not affected. We thus propose a structurally based mechanism for these differences between PAI-1 and PAI-2 and suggest that PAI-2 is able to inhibit and clear uPA activity without initiating mitogenic signalling events through VLDLr.
Configuration selection as a route towards efficient vibrational configuration interaction calculations
Authors: Rauhut Guntram
Published: November 2007

A configuration selective vibrational configuration interaction (CI) approach is presented that efficiently reduces the variational space and thus leads to significant speedups in comparison to standard vibrational CI implementations. Deviations with respect to reference calculations are well below the accuracy of the underlying electronic structure calculations for the potential and hence are essentially negligible. Parallel implementations of the presented configuration selective vibrational CI approaches lead to further significant time savings. Benchmark calculations based on potential energy surfaces of coupled-cluster quality are presented for the fundamental modes of cis- and trans-difluoroethylene. The size-consistency error within the vibrational configuration interaction calculations of the difluoroethylene dimer has been studied in dependence on the excitation level.
The stress generated by non-Brownian fibers in turbulent channel flow simulations
Authors: Gillissen J. J. J. , Boersma B. J. , Mortensen P. H. , Andersson H. I.
Published: November 2007

Turbulent fiber suspension channel flow is studied using direct numerical simulation. The effect of the fibers on the fluid mechanics is governed by a stress tensor, involving the distribution of fiber position and orientation. Properties of this function in channel flow are studied by computing the trajectories and orientations of individual particles, referred to as the particle method. It is shown that, due to computer restrictions, the instantaneous stress in channel flow cannot be simulated directly with the particle method. To approximate the stress we compute the second-order moment of the fiber distribution function. This method involves an unknown subgrid term, which is modeled as diffusion. The accuracy of the moment approximation is studied by comparing Reynolds averaged stress to results obtained from the particle method. It is observed that the errors are ∼1% for y+>20, and ∼20% for y+<20. The model is improved by applying a wall damping function to the diffusivity. The moment approximation is used to simulate drag-reduced channel flow. A simplified model for fiber stress is introduced as fiber viscosity times rate of strain, where fiber viscosity is defined as the ratio of Reynolds averaged dissipation due to fiber stress and Reynolds averaged dissipation due to Newtonian stress. Fluid velocity statistics predicted by the simple model compare very well to those obtained from the moment approximation. This means that the effect of fibers on turbulent channel flow is equivalent to an additional Reynolds averaged viscosity.
A fully relaxed helicity balance model for an inductively driven spheromak
Authors: O’Neill R. G. , Marklin G. J. , Jarboe T. R. , Akcay C. , Hamp W. T. , Nelson B. A. , Redd A. J. , Smith R. J. , Stewart B. T. , Wrobel J. S. , Sieck P. E.
Published: November 2007

Magnetic helicity balance and a fully relaxed Taylor-state model are shown to predict the magnitude of sustained equilibrium current in an inductively driven spheromak. The Helicity Injected Torus with Steady Inductive drive (HIT-SI) [T. R. Jarboe et al., Phys. Rev. Lett. 97, 115003 (2006)] forms and sustains spheromaks using two inductively driven helicity injectors. By assuming helicity is injected at a rate 2VΨ, and only decays through Spitzer resistivity using Te measured with a Langmuir probe, the magnitude of the sustained equilibrium current is predicted with no fitting parameters. The model correctly predicts a threshold helicity injection rate for spheromak formation. Although the experimental results suggest a higher effective helicity dissipation rate by a factor of ∼1.37 compared to the Spitzer value, the prediction is still within the uncertainties of the measured parameters.
Bifurcation and stability of near-critical compressible swirling flows
Authors: Rusak Z. , Choi J. J. , Lee J.-H.
Published: November 2007

The bifurcation and global nonlinear stability of near-critical states of a compressible and axisymmetric swirling flow of a perfect gas in a finite-length straight, circular pipe is studied. This work extends the bifurcation and stability analyses of Wang and Rusak [Phys. Fluids 8, 1007 (1996); Wang and Rusak Phys. Fluids8, 1017 (1996)] to include the influence of Mach number on the flow dynamics. The first- and second-order equations of motion for the evolution of small axially symmetric perturbations on a base columnar state are developed. These equations are reduced to an eigenvalue problem for the perturbation shape function and critical swirl ratio and a model ordinary differential equation for the nonlinear evolution of the perturbations’ amplitude as function of swirl level and Mach number. It is found that noncolumnar equilibrium states bifurcate from the branch of the base columnar equilibrium states at the critical swirl ratio of a compressible vortex flow in the form of a transcritical bifurcation, where both the critical swirl and the bifurcation slope ratio are functions of Mach number. It is also shown that this critical swirl ratio is a point of exchange of global stability for both the columnar and noncolumnar states as the swirl ratio increases across this critical level. When the swirl ratio of the incoming flow is below the critical level the columnar states have an asymptotically decaying mode of perturbation whereas the noncolumnar states are unstable. On the other hand, when the swirl ratio of the incoming flow is greater than the critical level, the columnar states are unstable whereas the noncolumnar states have an asymptotically decaying mode of disturbance. The effect of Mach number on the bifurcation behavior and on the stability characteristics of the various states is presented. The relationship between the present results and the breakdown of a compressible vortex flow is discussed.
Simulation of hydrodynamically interacting particles near a no-slip boundary
Authors: Swan James W. , Brady John F.
Published: November 2007

The dynamics of spherical particles near a single plane wall are computed using an extension of the Stokesian dynamics method that includes long-range many-body and pairwise lubrication interactions between the spheres and the wall in Stokes flow. Extra care is taken to ensure that the mobility and resistance tensors are symmetric, positive, and definite—something which is ineluctable for particles in low-Reynolds-number flows. We discuss why two previous simulation methods for particles near a plane wall, one using multipole expansions and the other using the Rotne-Prager tensor, fail to produce symmetric resistance and mobility tensors. Additionally, we offer some insight on how the Stokesian dynamics paradigm might be extended to study the dynamics of particles in any confining geometry.
Single-step controlled-NOT logic from any exchange interaction
Authors: Galiautdinov Andrei
Published: November 2007

A self-contained approach to studying the unitary evolution of coupled qubits is introduced, capable of addressing a variety of physical systems described by exchange Hamiltonians containing Rabi terms. The method automatically determines both the Weyl chamber steering trajectory and the accompanying local rotations. Particular attention is paid to the case of anisotropic exchange with tracking controls, which is solved analytically. It is shown that, if computational subspace is well isolated, any exchange interaction can always generate high fidelity, single-step controlled-NOT (CNOT) logic, provided that both qubits can be individually manipulated. The results are then applied to superconducting qubit architectures, for which several CNOT gate implementations are identified. The paper concludes with consideration of two CNOT gate designs having high efficiency and operating with no significant leakage to higher-lying noncomputational states.
Raman spectroscopy study of damage and strain in (001) and (011) Si induced by hydrogen or helium implantation
Authors: Villeneuve C. , Bourdelle K. K. , Paillard V. , Hebras X. , Kennard M.
Published: November 2007

We use Raman spectrometry to investigate lattice disorder and strain induced by hydrogen or helium implantation in (001) and (011) Si. The phonon peak intensities and the spatial correlation model are used to estimate the amount of damage affecting the phonon coherence length. The redshift due to reduced coherence length is taken into account to fit the model to the experimental spectra. This allows us to correctly estimate a blueshift attributed to a compressive in-plane strain. We observe that the amount of strain increases linearly with the implant dose. For H implants the dependence of strain on crystallographic orientation was discovered. This effect is attributed to the anisotropic morphology of the H-induced extended defects: two-dimensional platelets with preferred orientations versus spherical nanobubbles formed after He implants. Raman results are correlated with the implant damage simulations and compared with the data obtained by other characterization techniques.
Many-body effects in wide parabolic AlGaAs quantum wells
Authors: Tabata A. , Martins M. R. , Oliveira J. B. B. , Lamas T. E. , Duarte C. A. , da Silva E. C. F. , Gusev G. M.
Published: November 2007

Photoluminescence measurements at different temperatures have been performed to investigate the optical response of a two-dimensional electron gas in n-type wide parabolic quantum wells. A series of samples with different well widths in the range of 1000–3000Å was analyzed. Many-body effects, usually observed in the recombination process of a two-dimensional electron gas, appear as a strong enhancement in the photoluminescence spectra at the Fermi level at low temperature only in the thinnest parabolic quantum wells. The suppression of the many-body effect in the thicker quantum wells was attributed to the decrease of the overlap between the wavefunctions of the photocreated holes and the two-dimensional electrons belonging to the highest occupied electron subband.
Valence-band mixing effects in the exciton capture and escape in quantum-well structures
Authors: Chen Y. , Sadeghi S. M. , Huang W. P.
Published: November 2007

We study exciton capture and escape in shallow quantum wells including the effects of valence subband mixing. We show that such a mixing process has significant impacts, yielding one order of magnitude smaller capture and escape times than the previous results, which do not include band mixing. These results can have impacts on the various functionalities of optoelectronic devices, such as their speed and leakage currents.
Incorporation of tin in boron doped silicon for reduced deactivation of boron during post-laser-anneal rapid thermal processing
Authors: Liu Fangyue , Tan Kian-Ming , Wang Xincai , Low David Kuang Yong , Lai Doreen Mei Ying , Lim Poh Chong , Samudra Ganesh , Yeo Yee-Chia
Published: November 2007

The supersaturated and metastable boron produced by laser anneal could deactivate during post-laser-thermal-cycles and lead to undesirable performance degradation. The effect of tin incorporation on the thermal stability of boron was studied for the first time and suppressed boron deactivation during post-laser-rapid-thermal-anneal was observed with tin coimplantation. High resolution x-ray diffraction measurement indicates that the tensile strain caused by a high boron concentration was reduced by the introduction of tin, which effectively reduces the strain energy and therefore, enhances the thermal stability of boron in post-laser-anneal rapid thermal processing.
Making high resolution positioning independent of scan rates: A feedback approach
Authors: Shegaonkar Ajit C. , Salapaka Srinivasa M.
Published: November 2007

A feedback paradigm for achieving high resolution positioning for applications requiring repetitive motions such as image scanning in atomic force microscopy (AFM) is presented. The feedback scheme achieves very high resolution by compromising on the bandwidth of the device, even at high speeds, by making the device equivalent to a low bandwidth band pass filter with the central frequency corresponding to scan frequency. Application of this scheme on a flexure based stacked piezoactuated AFM scanner has demonstrated subnanometer resolution enabling atomic scale stick-slip images on mica, impossible otherwise. Experiments at high scan speeds using this scheme improved the positioning resolution by 96%.
Large negative magnetoresistance in Ge films at ultralow temperatures and low magnetic fields
Authors: Mitin V. F. , Dugaev V. K. , Ihas G. G.
Published: November 2007

Large negative magnetoresistance is found in Ge films, used as ultralow-temperature resistance thermometers, at temperatures below 0.2K and magnetic fields below 1T. This effect is very sensitive to temperature. At T<0.3K, the magnetoresistance is negative, and its magnitude increases with decreasing temperature. At 0.03K, the resistance strongly decreases (up to 100 times) when the magnetic field is increased from 0to1T and then saturates in higher fields. We discuss the mechanisms of this phenomenon and present results of calculations involving the hopping theory of conductivity with localization corrections.
Thermal properties and percolation in carbon nanotube-polymer composites
Authors: Bonnet P. , Sireude D. , Garnier B. , Chauvet O.
Published: November 2007

Thermal properties of single walled carbon nanotube (SWNT)/polymethylmetacrylate composite thick films have been investigated at room temperature. The introduction of ∼7% SWNT into the polymer matrix enhances the thermal conductivity of the composite by 55% while the electrical conductivity increases by several orders of magnitude. Despite this difference, we show that the (moderate) enhancement of the thermal conductivity is quantified by the percolation of the SWNT network. A thermal conductivity of the SWNT network of ∼55W∕mK is estimated.
Zone sculpting using partitioned electrokinetic injections
Authors: Narovlyansky Max , Whitesides George M. , Squires Todd M.
Published: November 2007

We describe a general and versatile method to sculpt low-dispersion, high-fidelity sample zones in microfluidic devices for high resolution electrokinetic separations. In a simple channel intersection, microfabricated partitions reduce each channel’s permittivity to transverse electric fields, yet maintain their permeability to parallel fields. The resulting anisotropy effectively confines fields to the intersection, thus sculpting the injected plug. We demonstrate by injecting narrow yet symmetric sample zones in a poly(dimethylsiloxane) microfluidic device. This simple geometric strategy for sculpting the field and flow lines does not depend on the device material or analyte/electrolyte properties, and is limited in scale only by fabrication capabilities.
Entanglement generation using silicon wire waveguide
Authors: Takesue Hiroki , Tokura Yasuhiro , Fukuda Hiroshi , Tsuchizawa Tai , Watanabe Toshifumi , Yamada Koji , Itabashi Sei-ichi
Published: November 2007

We report an entanglement generation experiment that utilizes a silicon waveguide. Using spontaneous four-wave mixing in a 1.09-cm-long silicon wire waveguide, we generated 1.5μm, high-purity time-bin entangled photons without temperature control and observed a two-photon interference fringe with >73% visibility.
Transmission of pillar-based photonic crystal waveguides in InP technology
Authors: Kok Abigaël , Geluk Erik Jan , Docter Boudewijn , van der Tol Jos , Nötzel Richard , Smit Meint , Baets Roel
Published: November 2007

Waveguides based on line defects in pillar photonic crystals have been fabricated in InP∕InGaAsP∕InP technology. Transmission measurements of different line defects are reported. The results can be explained by comparison with two-dimensional band diagram simulations. The losses increase substantially at mode crossings and in the slow light regime. The agreement with the band diagrams implies a good control on the dimensions of the fabricated features, which is an important step in the actual application of these devices in photonic integrated circuits.
Optical limiting using Laguerre-Gaussian beams
Authors: Zhang Weiya , Kuzyk Mark G.
Published: November 2007

We demonstrate optical limiting using the self-lensing effect of a higher-order Laguerre-Gaussian beam in a thin dye-doped polymer sample, which we find consistent with our model using Gaussian decomposition. The peak phase shift in the sample required for limiting is smaller than that for a fundamental Gaussian beam with the added flexibility that the nonlinear medium can be placed either in front of or behind the beam focus.
A comparison of tree water use in two contiguous vegetation communities of the seasonally dry tropics of northern Australia: the importance of site water budget to tree hydraulics
Authors: Kelley G. , O'Grady A. P. , Hutley L. B. , Eamus D.
Published: November 2007

Tree water use in two contiguous communities (eucalypt open-forest and Melaleuca paperbark forest) was measured in tropical Australia, over a 2-year period. The aims of the study were to (1) quantify daily and seasonal patterns of water use in each community, (2) compare patterns of water use among the communities and (3) compare relationships among tree size, sapwood area and water use within the two contrasting vegetation communities. Access to deep soil water stores and the effect of run-on from the eucalypt forest resulted in a relatively high pre-dawn water potential throughout the year, particularly for Melaleuca forest. There were no differences in daily rates of water use, expressed on a sapwood area (Q
s) basis, between the two eucalypt species examined (Eucalyptus miniata Cunn. Ex Schauer and E. tetrodonta F.Muell) at any time in the eucalypt forest. For both the eucalypt and Melaleuca forests, there was less seasonal variation in water use expressed on a leaf area (Q
l) basis than on a Q
s basis, and neither year nor season were significant factors in Q
l. In the mono-specific Melaleuca forest, Q
s was not significantly different between years or seasons. Water use on a Q
l basis was similarly not significantly different between years or seasons in the Melaleuca forest. Leaf area index (LAI) of the eucalypt forest was about half of that of the Melaleuca forest throughout the year but sapwood area per hectare was 33% larger in the eucalypt than the Melaleuca forest, despite the basal area of the Melaeuca forest being almost double that of the eucalypt forest. There was no significant difference in stand water use (mm day–1) between eucalypt and Melaleuca forests during 1998; however, in 1999 Melaleuca stand water use was larger than that of the eucalypt forest. Because of the enhanced dry-season availability of water in the Melaleuca forest and its larger LAI, average annual water use of the Melaleuca forest was almost 60% larger than that of the eucalypt forest. Despite differences in Q
l, Q
s and annual water use between forests, the ratio of LAI to stand water use was similar for all seasons in both forests. The applicability of ‘universal rules’ linking tree water use and tree hydraulics and the importance of ecosystem location on site water budgets and plant adaptations are discussed.
Petroleum geophysics - four decades of progress
Authors: McNatt E.M.
Published: November 2007

Progress in petroleum geophysics is, of course, inevitably bound up with the progress of petroleum exploration. In fact, some of us tend to think that advances in exploration technology are primarily the result of progress in geophysics! In any event, by way of introduction, I would like to review briefly how petroleum exploration has evolved from early days to its present state.
Geophysics in the mineral industry today
Authors: Seigel H.O.
Published: November 2007

I am going to start out by listing a few things that might be considered fairly new in exploration in mining geophysics and then sort of fit them into context in a more general over-view.
Computer programs for Turam data reductions
Authors: Williams J.P.
Published: November 2007

A computer program TURAMTAB was written to compute the reciprocals of theoretical Turam ratios at any required point outside, but, in the plane of a specified rectangular transmitting loop. A program TURAMBUK was written to produce tables for efficient reduction of measured Turam ratios. These programs are outlined briefly and their usefulness discussed.
Recent trends in computer contouring
Authors: Crain I.K.
Published: November 2007

The contour map is, by far, the most common display mode for geophysical and geological data. With the increasing use of computers in geophysical data analysis, the demand for computer contoured maps is rapidly growing. Computer contouring has been available on a fairly routine basis for about ten years (see, for example, Dayhoff, 1963), but in spite of this, much programming effort (and money) is still being devoted to the research and development of new contouring programs. The main reason for this continuing research is the failure of previous effort to establish an interpolation technique for irregularly spaced data which gives consistently "good" results, under what- ever definition of "good" is applied. The purpose of this note is to describe the directions of some recent research into the contouring problem, and hopefully to suggest in which direction the ultimate solution may lie.
Airborne seismic survey in northern New Guinea
Authors: Brown A.R.
Published: November 2007

The Bureau of Mineral Resources is conducting an experimental airborne seismic survey in the Sepik-Ramu area of northern New Guinea between October and December this year.
When the dipole geomagnetic field dwindles away
Authors: Facer R.A.
Published: November 2007

It is now widely accepted that the geomagnetic field changes sign from time to time, generally irregularly, this "reversal" being accompanied by a decrease in intensity. Study of these changes in the past geomagnetic field has been limited to consideration of the dipole field. Unfortunately, the non-dipole geomagnetic field is more significant than has been considered previously - not only in palaeo-magnetism (Facer, 1970), but perhaps in the future in exploration magnetic studies also.
The role of geology and geophysics in mineral exploration
Authors: Shalley M.J.
Published: November 2007

Mineral Exploration starts and finishes with geology. Geophysics, in its proper place, is a service to the geologist to assist him to come as close as possible to the truth in a given geological situation. It is, generally speaking, a science of the sub-surface - a tangible way of dealing with intangibles. It could, in fact, be described as a method of quantifying the unknown.
A simple direct method for computing the parameters of a buried disc from the results of a gravity survey
Authors: Lee T.
Published: November 2007

The vertical component of the gravitational field across a right vertical disc may be formulated in terms of elliptic integrals. This may be transformed into a more manageable form by the Hankel transform. The transformed integrals give relationships from which a unique solution for the radius of the disc, the thickness and the depth of burial may be readily obtained, for a given density. The method has been programmed for a computer and has been found to produce rapid and reliable results.
Geophysical exploration for buried river channels in the Gulgong Goldfields N.S.W.
Authors: Whiteley R.J.
Published: November 2007

A detailed magnetic and gravity survey was done on portion of the Gulgong Goldfields, New South Wales. The geophysical survey was undertaken to study the geology in an area blanketed by a thick alluvial cover and in particular to investigate a buried, Tertiary river system. This system is known to be present and was once the object of active gold mining operation. The magnetic survey revealed a complex anomaly pattern containing both normal and reversed anomalies. These features were difficult to interpret due to the paucity of geological information and did not appear to be related to the channel structures. The gravity survey was successful in distinguishing the generally broad bedrock depressions associated with the gold-bearing channels. Owing to the presence of a complex regional feature, qualitative interpretation was simplified by applying a number of second derivative operators to the gravity data. Quantitative interpretation wer known ground suggested that lateral density variations within the bedrock or alluvium did not significantly contribute to the measured anomalies and that a density contrast of 0.5 gm/cc exiats between the bedrock and alluvium.