bluuebunny/crossref_metadata_2025 huggingface dataset:
Intradermal positivity after negative prick testing for inhalants
Authors: McKay Shawn P. , Meslemani Danny , Stachler Robert J. , Krouse John H.
Published: August 2006

Objective

Examine the incidence of positive intradermal tests after a negative skin prick test for 24 inhalant antigens.

Study Design and Setting

Retrospective study. Charts from patients who underwent modified quantitative testing over a 3‐year period were reviewed. Patients were initially tested with Multi‐Test II. Subjects with negative wheals to a specific allergen were then tested with a 1:500 weight:volume intradermal injection of that allergen.

Results

One hundred thirty‐three patients underwent MQT for 24 antigens. Allergens with the highest incidence of positive intradermal wheals after negative prick testing were Dermatophagoides pteronyssinus and Dermatophagoides farinae at 26.67%. Allergens with elevated incidence of positive intradermals included fusarium, cockroach, cocklebur, rough marsh elder, and ragweed, all with incidences of 16% to 19%.

Conclusion

Positive intradermal responses after negative prick testing occur commonly. Future study is needed to determine the generalizability and clinical significance of these findings.

EBM rating: C‐4
Reliable surgical landmarks for the identification of the recurrent laryngeal nerve
Authors: Çakir Burak Ömür , Ercan Ibrahim , Şam Bülent , Turgut Suat
Published: August 2006

Objective

To obtain reliable landmarks for identification of the recurrent laryngeal nerve in human larynges.

Study Design and Setting

This is a prospective study, analyzing the laryngeal anatomic features. Structures easily palpable on the thyroid and cricoid cartilage (ie, the most prominent portion of the inferior cornu of the thyroid cartilage [IC], the inferior tubercle of the thyroid cartilage [ITT] and the most anterior portion of the arch of the cricoid cartilage [AC]) were accepted as landmarks and the distances of these structures to the entrance point of the RLN on the medial aspect of the inferior pharyngeal constrictor muscle (cross point [CP]) were measured in 65 adult autopsies.

Results

When a straight line is drawn 11 to 12 millimeters (mm) from the IC, 22 to 24 mm from the ITT, and 26 to 28 mm from the AC, the point at which they intersect indicates the point at which the RLN enters the medial side of the inferior pharyngeal constrictor muscle (ICM) and is easy to locate at this point. All of the RLN were seen to lie posterolateral to the Berry ligament. Thirty‐eight of 65 cases possessed extralaryngeal bifurcation of the RLN.

Conclusion

With such constant mathematic values, these 3 landmarks are reliable markers for identification of RLN. This study is important in the fact that it states constant mathematic values regarding surgical landmarks used to expose the RLN.
Palatal and tongue base surgery for surgical treatment of obstructive sleep apnea: A prospective study
Authors: Jacobowitz Ofer
Published: August 2006

Objective

To assess the effect of concurrent uvulopalatopha‐ryngoplasty and hypopharyngeal procedures in obstructive sleep apnea (OSA) patients with diffuse airway narrowing.

Study Design and Setting

Forty‐eight patients were treated surgically by a single surgeon in private practice over 2 years. Symptoms, Epworth score, and polysomnographic outcome were assessed preoperatively and postoperatively. The Friedman staging system was applied. UPPP with genioglossus advancement, hyoid suspension, or radiofrequency treatment was carried out.

Results

In 37 patients with complete data, the average apnea‐hypopnea index (AHI) was reduced from 46.5 ± 24.8 to 14.9 ± 16.8. The Epworth score was reduced from 12.1 ± 4.9 to 6.7 ± 3.7. Most patients reported improved sleep quality, alertness, memory, concentration, and mood.

Conclusion

Successful outcome, defined by symptom and AHI reduction, was achieved with multilevel surgery for most patients with advanced Friedman stages 2 and 3.

Significance

Multilevel surgery seems effective in treating severe OSA patients with diffuse airway narrowing.

EBM rating: C‐4
DQA1 and DQB1 association and nasal polyposis
Authors: Fajardo‐Dolci Germán , Solorio‐Abreu Jesús , Romero‐Álvarez Julio César , Zavaleta‐Villa Beatríz , Cerezo‐Camacho Oscar , Jiménez‐Lucio Rocío , Olivo‐Díaz Angélica
Published: August 2006

Objective

The aim of this study was to determine the contribution of the human major histocompatibility complex (HLA)‐DQA1, ‐DQB1, and TNFΑ genes with simple nasal polyposis.

Study Design and Setting

A comparative case‐control study with 31 patients and 151 controls was performed. HLADQA1, ‐DQB1, and TNFΑ −238 promoter position loci were typed by polymerase chain reaction (PCR) and sequence specific oligonucleotide probes (SSOPs). TNFΑ ℒ308 promoter position was determined by PCR and digestion with NcoI restriction enzyme.

Results

The allele HLA‐DQA1*0201 (Pc = 0.019) had an etiologic fraction (EF) of 17%, whereas 13% EF was found for the haplotype HLA‐DQA1*0201‐DQB1*0201 (P = 0.016). Analysis of ‐DQB1 and TNFΑ promoter did not show significant differences between cases and controls.

Conclusions

HLA‐DQA1*0201‐DQB1*0201 haplotype is involved in susceptibility, conferring 5.53 times more risk of developing this disease.

EBM rating: B−2b
Factors influencing publication of abstracts presented at the AAO‐HNS Annual Meeting
Authors: Peng Phyllis H. , Wasserman Jared M. , Rosenfeld Richard M.
Published: August 2006

Objective

To examine abstracts presented at the American Academy of Otolaryngology‐Head and Neck Surgery Annual Meeting and to identify factors associated with publication success.

Study Design and Setting

All abstracts published in the August 1999 official program issue of the AAO‐HNS Journal were examined. MEDLINE searches were performed to assess publication success. Multivariate analysis was performed to identify factors related to successful publication.

Results

We identified 473 abstracts, of which 260 (55%) were poster presentations. Median publication time was 16 months, with a publication rate of 50%. Multivariate analysis revealed oral presentation, statistical analysis, and number of authors to be the most significant predictive factors of publication success (odds ratios of 2.2, 1.9, and 1.2 respectively). Level of evidence did not correlate with publication success, even when case reports (n = 70) were excluded from the analysis. Publication rates in other disciplines ranged from 25% to 68%, with a mean of 47%.

Conclusions

The rate of publication from the AAO‐HNS Annual Meeting is similar to other disciplines. Oral presentations with inferential statistics in the abstract were most likely to be published. Conversely, level of evidence and direction of study inquiry were not significant predictors, suggesting that research design is a less important determinant of publication success.

Significance

Our investigation is one of the first to critically analyze the factors in presentations at annual meetings that predict successful publication.
Sound and complete models of contracts
Authors: BLUME MATTHIAS , McALLESTER DAVID
Published: August 2006

Even in statically typed languages it is useful to have certain invariants checked dynamically. Findler and Felleisen gave an algorithm for dynamically checking expressive higher-order types called contracts. They did not, however, give a semantics of contracts. The lack of a semantics makes it impossible to define and prove soundness and completeness of the checking algorithm. (Given a semantics, a sound checker never reports violations that do not exist under that semantics; a complete checker is – in principle – able to find violations when violations exist.) Ideally, a semantics should capture what programmers intuitively feel is the meaning of a contract or otherwise clearly point out where intuition does not match reality. In this paper we give an interpretation of contracts for which we prove the Findler-Felleisen algorithm sound and (under reasonable assumptions) complete. While our semantics mostly matches intuition, it also exposes a problem with predicate contracts where an arguably more intuitive interpretation than ours would render the checking algorithm unsound. In our semantics we have to make use of a notion of safety (which we define in the paper) to avoid unsoundness. We are able to eliminate the “leakage” of safety into the semantics by changing the language, replacing the original version of unrestricted predicate contracts with a restricted form. The corresponding loss in expressive power can be recovered by making safety explicit as a contract. This can be done either in ad-hoc fashion or by including general recursive contracts. The addition of recursive contracts has far-reaching implications, deeply affecting the formulation of our model and requiring different techniques for proving soundness.
Multi-return function call
Authors: SHIVERS OLIN , FISHER DAVID
Published: August 2006

It is possible to extend the basic notion of “function call” to allow functions to have multiple return points. This turns out to be a surprisingly useful mechanism. This article conducts a fairly wide-ranging tour of such a feature: a formal semantics for a minimal $\lambda$-calculus capturing the mechanism; motivating examples; monomorphic and parametrically polymorphic static type systems; useful transformations; implementation concerns and experience with an implementation; and comparison to related mechanisms, such as exceptions, sum-types and explicit continuations. We conclude that multiple-return function call is not only a useful and expressive mechanism, at both the source-code and intermediate-representation levels, but also quite inexpensive to implement.
Venice, print, and the early modern icon
Authors: WILSON BRONWEN
Published: August 2006

Venetian printmakers in the sixteenth century were enthusiastic participants in what became a project of civic self-promotion as they looked beyond the local market to an international one. In response to the fascination of foreigners who marvelled at the city's singular topography and its reputation for liberty and licentiousness, the bird's-eye view and images of local social types – such as the doge and courtesan – became transmuted into icons of the city's urban identity. The medium and modes of representation used to reproduce the republic's social and physical organization on paper are crucial here, for it was the repetition and sedimentation of visual conventions that forged iconicity. Venice was redefined as a centre in which all the world could be seen. And the mechanisms for this redefinition, as this article argues, emerged, in part, out of print, for it was because the city could be seen from the eye of a bird, on paper as an image, by foreigners – that it could be re-envisioned from the outside in.
The kinetic icon: Reyner Banham on Los Angeles as mobile metropolis
Authors: DIMENDBERG EDWARD
Published: August 2006

Architectural historian P. Reyner Banham (1922–88) is widely known for his numerous writings on the modern built environment, including the book Los Angeles: The Architecture of Four Ecologies (1971). In the BBC television film Reyner Banham Loves Los Angeles (Julian Cooper, 1972), he concretized his earlier insights about the importance of mobility in the Southern California metropolis by employing the proclivity of the cinematic medium to represent movement. While traditional notions of the urban icon commonly understand it as a static monument or landmark, in these two works Banham challenges the suitability of this view to a city as inflected by automobility as Los Angeles and proposes the motorway and the experience of driving as its most characteristic iconic forms.
Review of periodical articles
Authors: BRODT BÄRBEL , ELLIOTT PAUL , MISKELL LOUISE
Published: August 2006

Just as nature fails to produce the ‘perfect harvest’ with predictable regularity, so does the quantity of medieval urban periodical publications vary. The crop of 2005 falls well behind the richer harvests of previous years, in quantity though not in quality of the published work. Two impressions of this work: first, there are fewer obvious ‘themes’ which seem to preoccupy the authors' minds; but, secondly, articles by German and Austrian scholars show a greater concern with the exposition and analysis of major urban themes than do those from the English-speaking world. One wonders why. Could it be that German-speaking urban historians are less hesitant to re-address the seemingly obvious? Two prime examples here are presented by the contributions of Ferdinand Opll and Benjamin Scheller.
Food, drink and public order in the London Liber Albus
Authors: CARREL HELEN
Published: August 2006

This article provides a detailed study of the Liber Albus, a London custumal compiled in 1419 by John Carpenter, Common Clerk of the City, under the direction of the mayor, Richard Whittington. It explores how the manuscript demonstrated a growing conservatism in early fifteenth-century London government, especially in relation to the regulation of the food trade and matters of public order, linking this to memories of late fourteenth-century turbulence in the City and poor relations with the Crown.
Towns, improvement and cultural change in Georgian Scotland: the evidence of the Angus burghs, c. 1760-1820
Authors: HARRIS BOB
Published: August 2006

This article uses the concept of ‘improvement’ to examine the experiences of five burghs in Angus – Dundee, Montrose, Forfar, Brechin and Arbroath – in the later Georgian era. Designed as a contribution to British history in a comparative sense, and using the five burghs as case studies, it seeks to identity distinctively Scottish, as well as common, British elements in Scottish urbanization during a crucial phase in its development. Existing studies of Scottish urban society in this period focus very heavily on the impact of industrialization on large towns and cities, especially Glasgow. Partly as a result, other themes have been neglected or obscured. A second main aim, therefore, is to offer an alternative framework for understanding the development and experiences of the smaller towns in which most of the Scottish urban population lived prior to 1830.
Research in urban history: a review of recent theses
Authors: MILLER CAROLINE L.
Published: August 2006

In keeping with past experiences, 2005 produced a rich range of 70 theses that address urban history topics. Equally, as in past years, the topics the theses address are marked by diversity that itself is reflective of the nature of the urban experience. As usual the theses reviewed here are drawn from the Index of Theses located at http://www.theses.com/, which now also features Irish theses, and Dissertations International located at http://wwwli.umi.com/dissertations. This year's crop of theses has proved somewhat easier to categorize than has been the case in previous years and has seen the emergence of some new topics. In particular there is a noticeable interest in what might be called the urban environment and its functioning, which leads to interest in the infrastructural aspects of the city. This is not a new agenda for urban historians but it does also reflect the growth of environmental history and seems to represent an intersection of the two areas. It is also a consequence of the dominance of the nineteenth and twentieth centuries in urban history, which of itself tends to bring infrastructure to the historian's notice. Another interesting area of study that is emerging as the result of the opening of Soviet era archives is that of city planning, reconstruction and history in the former Soviet Union and eastern bloc countries. Theses from American universities continued to predominate with 68 per cent being drawn from their institutions. The proportion from Great Britain dropped to 21 per cent but the percentage from other countries, predominantly Canadian universities, increased to 11 per cent. The earlier production of this article may be the reason for the reduction in the British proportion rather than a real decline in numbers. There were noticeable clusters of theses coming from Stanford University (7.6 per cent of the total), with the University of Pennsylvania and Columbia University each producing 6.1 per cent of the theses produced. In Britain there was a small cluster that emerged from the Open University and among the ‘other’ group, Toronto University was the only institution to produce more than one thesis.
Subduction history of the Tethyan region derived from seismic tomography and tectonic reconstructions
Authors: Hafkenscheid E. , Wortel M. J. R. , Spakman W.
Published: August 2006

In the mantle underneath the Tethyan suture zone, large volumes of positive velocity anomalies have been imaged by seismic tomography and interpreted as the present‐day signature of subducted Tethyan lithosphere. We investigate the Mesozoic‐Cenozoic subduction history of the region by integrating independent information from mantle tomography and tectonic reconstructions. Three different subduction scenarios for the Tethyan oceanic lithosphere, representative for the available tectonic reconstructions, are used to predict the present thermally anomalous volumes associated with the lithospheric surface subducted since the late Mesozoic. Next, these predicted thermal volumes and their expected positions are compared to the relevant anomalous volumes derived from seismic tomographic images. In this analysis we include, among others, the possible effects of ridge subduction and slab detachment after the Cenozoic continental collisions, absolute plate motion, and slab thickening in the mantle. Our preferred subduction model comprises the opening of large back‐arc oceanic basins within the Eurasian margin. The model points to slab thickening by a factor of 3 in the mantle, in which case the estimated volumes allow for active oceanic spreading (∼1–2.5 cm/yr) in the Tethyan lithosphere during convergence. Our results further indicate the occurrence of early Oligocene slab detachment underneath the northern Zagros suture zone, followed by both westward and eastward propagation of the slab tear and diachronous Eocene to Miocene slab detachment below the eastern to western Himalayas. Free sinking rates of the detached material of ∼2 cm/yr in the lower mantle provide the best fit between the tomographic mantle structure and our Tethyan subduction model.
Solar spectral actinic flux and photolysis frequency measurements in a deciduous forest
Authors: Bohn B.
Published: August 2006

Within the Emission and Chemical Transformation of Biogenic Volatile Organic Compounds (ECHO) project the photochemistry of biogenic organic compounds in a forest was investigated. In this context, two spectroradiometers were used to determine solar spectral actinic flux and photolysis frequencies within and above a deciduous forest at Jülich, Germany. Locations in the forest and in a small clearing were examined 2 m above ground. Under overcast conditions, photolysis frequencies were within 1–3% and 6–8% of above canopy values at forest and clearing locations, respectively. In a spectral range below 500 nm the canopy was found to act as a gray filter that diminished spectral actinic flux independent of daytime and wavelength. Under clear‐sky conditions, diurnal variations within the forest also followed that of diffuse sky radiation above the forest except for sharp peaks from direct sunlight that was incident sporadically at the selected locations. The results under all conditions were in accord with the foliage being opaque toward UV and gaps in the canopy being responsible for the remaining actinic flux. Sky photographs showed that the distribution and size of gaps in the foliage were extremely heterogeneous with patterns changing rapidly upon changing location. Regarding daytime chemical reactions of biogenic compounds within the forest, it was estimated that degradation by OH was reduced by a factor similar to the photolysis frequencies, while potential degradation by NO3 was increased by a factor of ∼3 compared with above forest conditions. As a result, it was estimated that minor fractions of 0.8% of isoprene and 3.4% of monoterpenes were degraded by reactions with OH, NO3, and O3 prior to transport into the layer above the forest.
Effects of aerosols on the surface solar radiation in a tropical urban area
Authors: Chou Ming‐Dah , Lin Po‐Hsiung , Ma Po‐Lun , Lin Ho‐Jiunn
Published: August 2006

Surface radiation measurements at an urban site in southern Taiwan during the dry winter season, December 2003 to March 2004, are used to investigate the aerosol properties and the effects of aerosols on the surface solar radiation in clear skies. The AERONET‐retrieved monthly mean aerosol optical thickness at 0.5 μm ranges from 0.52 to 1.18 with a mean of 0.73 for the four winter months. The single‐scattering albedo and asymmetry factor remain nearly constant with a mean of ∼0.95 for the former and ∼0.70 for the latter. Thus the air of Tainan during the winter is highly polluted, and the aerosols are moderately absorbing. A new approach is developed to estimate the effect of aerosols on the surface radiation from surface observations. The relationship between the surface radiation and the aerosol optical thickness is established for narrow intervals of the solar zenith angle by regression of the atmospheric path transmission against the aerosol optical path. It is found that the relationship is surprisingly linear. On the basis of the relationship the effect of aerosols on the surface radiation and the sensitivity of surface radiation to the aerosol optical thickness are computed. For the four‐month average, the effect of aerosols is to reduce the incident surface solar radiation by ∼39 W m−2, and the sensitivity of the surface radiation to aerosols undergoes a reduction of ∼53 W m−2 per unit increase of the aerosol optical thickness at 0.5 μm. These results are in good agreement with radiative transfer model calculations.
Coincident vortices in Antarctic wind fields and sea ice motion
Authors: Wassermann S. , Schmitt C. , Kottmeier C. , Simmonds I.
Published: August 2006

This study introduces a method to examine the coincidence of rotational ice drift and winds caused by the forcing of ice motion by Antarctic cyclones. Vortices are automatically detected using the algorithm of Murray and Simmonds (1991) from both ECMWF surface pressures and SSM/I sea ice motions. For compatibility with this algorithm sea ice motion vectors are transformed to a scalar stream function. During a seven‐day test period positions of pressure minima and stream function maxima (SFM) of ice drift are within 300 km in 96% of the cases. Lowest pressure minima are related to highest stream function maxima. The results promise the method to provide a complementary tool of detecting and localizing low‐pressure systems over sea ice, adding to numerical pressure analyses.
A Siberian precursor to midwinter intraseasonal variability in the North Pacific storm track
Authors: Robinson Dennis P. , Black Robert X. , McDaniel Brent A.
Published: August 2006

An observational diagnostic analysis is performed to study variations in the behavior of upper tropospheric Rossby waves prior to intraseasonal variability in the North Pacific storm track. The research is motivated from considerations of the midwinter suppression of the North Pacific storm track. During midwinter strong upper tropospheric cyclone events in the North Pacific storm track are preceded 7 days by a large‐scale cyclonic circulation anomaly located over Siberia. The Siberian precursor anomaly is found to be strongly linked to one of the primary modes of upper tropospheric intraseasonal variability over Asia. More generally, this Asian mode is determined to provide a substantial modulation in the structure and amplitude of the North Pacific storm track at lead times of +5 to +8 days. This downstream influence is concentrated during midwinter and is likely related to intraseasonal variations in the East Asian winter monsoon.
In vitropharmacological characterization of AM1241: a protean agonist at the cannabinoid CB2receptor?
Authors: Yao B B , Mukherjee S , Fan Y , Garrison T R , Daza A V , Grayson G K , Hooker B A , Dart M J , Sullivan J P , Meyer M D
Published: August 2006

Background and purpose:

The CB2receptor has been proposed as a novel target for the treatment of pain, and CB2receptor agonists defined inin vitroassays have demonstrated analgesic activity in animal models. Based on itsin vivoanalgesic efficacy, AM1241 has been classified as a CB2‐selective agonist. However,in vitrocharacterization of AM1241 in functional assays has not been reported.

Experimental approach:

In this study, AM1241 was characterized across multiplein vitroassays employing heterologous recombinant receptor expression systems to assess its binding potencies at the human CB2and CB1receptors and its functional efficacies at the human CB2receptor.

Key results:

AM1241 exhibited distinct functional properties depending on the assay conditions employed, a unique profile in contrast to those of the agonist CP 55,940 and the inverse agonist SR144528. AM1241 displayed neutral antagonist activities in FLIPR and cyclase assays. However, when cyclase assays were performed using lower forskolin concentrations for stimulation, AM1241 exhibited partial agonist efficacy. In addition, it behaved as a partial agonist in ERK (or MAP) kinase assays.

Conclusions and implications:

The unusual phenomenon of inconsistent functional efficacies suggests that AM1241 is a protean agonist at the CB2receptor. We postulate that functional efficacies displayed by protean agonists in various assay systems may depend on the levels of receptor constitutive activities exhibited in the assay systems, and therefore, efficacies observed inin vitroassays may not predictin vivoactivities.

British Journal of Pharmacology(2006)149, 145–154. doi:10.1038/sj.bjp.0706838
Linear and nonlinear theory of long-wave Marangoni instability with the Soret effect at finite Biot numbers
Authors: Podolny A. , Oron A. , Nepomnyashchy A. A.
Published: August 2006

We investigate the long-wave Marangoni instability in binary-liquid layers in the presence of the Soret effect in the case of finite Biot numbers. Linear stability theory reveals both long-wave monotonic and oscillatory modes of instability in various parameter domains. A set of nonlinear evolution equations governing the spatiotemporal dynamics of a thin binary-liquid film is derived. Based on this set of equations, weakly nonlinear analysis is carried out. Selection of stable supercritical patterns is investigated in the limit of low gravity. Various parameter domains are examined in which supercritical standing and traveling waves are found. Stability of superposed two-wave traveling solutions is also investigated.
Experimental investigation of vortex properties in a turbulent boundary layer
Authors: Ganapathisubramani Bharathram , Longmire Ellen K. , Marusic Ivan
Published: August 2006

Dual-plane particle image velocimetry experiments were performed in a turbulent boundary layer with Reτ=1160 to obtain all components of the velocity gradient tensor. Wall-normal locations in the logarithmic and wake region were examined. The availability of the complete gradient tensor facilitates improved identification of vortex cores and determination of their orientation and size. Inclination angles of vortex cores were computed using statistical tools such as two-point correlations and joint probability density functions. Also, a vortex identification technique was employed to identify individual cores and to compute inclination angles directly from instantaneous fields. The results reveal broad distributions of inclination angles at both locations. The results are consistent with the presence of many hairpin vortices which are most frequently inclined downstream at an angle of 45∘ with the wall. According to the probability density functions, a relatively small percentage of cores are inclined upstream. The number density of forward leaning cores decreases from the logarithmic to the outer region while the number density of backward-leaning cores remains relatively constant. These trends, together with the correlation statistics, suggest that the backward-leaning cores are part of smaller, weaker structures that have been distorted and convected by larger, predominantly forward-leaning eddies associated with the local shear.
Analysis of passive scalar gradient alignment in a simplified three-dimensional case
Authors: Garcia A. , Gonzalez M.
Published: August 2006

Numerical simulations as well as recent experiments in turbulent three-dimensional flow show a trend of the gradient of a passive scalar to align with the compressional axis of the strain tensor. In two-dimensional flow, however, it has been proved that the most probable orientation of the scalar gradient can be different from the compressional direction. An idealized situation is used to address this question in the three-dimensional case and to suggest a possible way to reexamine the scalar gradient alignment in three-dimensional flow. This kind of analysis can be applied to the material line alignment as well.
Wall slip of bubbles in foams
Authors: Saugey A. , Drenckhan W. , Weaire D.
Published: August 2006

We present a computational analysis of the flow of liquid foam along a smooth wall, as encountered in the transport of foams in vessels and pipes. We concentrate on the slip of the bubbles at the wall and present some novel finite element calculations of this motion for the case of fully mobile gas/liquid interfaces. Our two-dimensional simulations provide for the first time the bubble shapes and entire flow field, giving detailed insight into the distribution of stresses and dissipation in the system. In particular, we investigate the relationship between the drag force and the slip velocity of the bubble, which for small slip velocities obeys power laws, as predicted by previous semianalytical treatments.
A synthetic perturbative hypothesis for multiscale analysis of convective wake instability
Authors: Tordella D. , Scarsoglio S. , Belan M.
Published: August 2006

The paper presents a nonparallel stability analysis of the intermediate region of the two-dimensional wake behind a bluff body. In particular, it analyzes the convective instabilities using a Wentzel-Kramers-Brillouin-Jeffreys method on a basic flow previously derived from intermediate asymptotics [D. Tordella and M. Belan, Phys. Fluids 15, 1897 (2003)]. The multiscaling is carried out to explicitly account for the effects associated to the lateral momentum dynamics at a given Reynolds number. These effects are an important feature of the base flow and are included in the perturbative equation as well as in the associated modulation equation. At the first order in the multiscaling, the disturbance is locally tuned to the property of the instability, as can be seen in the zero-order theory (near-parallel parametric Orr-Sommerfeld treatment). This leads to a synthetic analysis of the nonparallel correction of the instability characteristics. The system is, in fact, considered to be locally perturbed by waves with a wave number that varies along the intermediate wake and which is equal to the wave number of the dominant saddle point of the zero order dispersion relation, taken at different Reynolds numbers. In this study, the Reynolds number is thus the only parameter. It is shown that the corrections to the frequency, and to the temporal and spatial growth rates are remarkable in the first part of the intermediate wake and lead to absolute instability in regions that extend to about ten body scales. The correction increases with the Reynolds number and agrees with data from laboratory and numerical experiments in literature. An eigenfunction and eigenvalue asymptotic analysis for the far wake is included, which is in excellent agreement with the complete problem.
Partial coalescence between a drop and a liquid-liquid interface
Authors: Chen Xiaopeng , Mandre Shreyas , Feng James J.
Published: August 2006

This Letter reports experimental results for partial coalescence when a drop merges with an interface. We find an intermediate range of drop sizes in which the merger is not complete but a daughter drop is left behind. This phenomenon is governed primarily by inertia and interfacial tension, and three regimes can be further delineated depending on the roles of viscosity and gravity. Scaling relationships are developed for the drop size ratio and the coalescence time. For drops that are too large or too small, partial coalescence is arrested by gravity or viscosity, respectively.
Buoyancy and surface tension driven convection around a bubble
Authors: Savino R. , Fico S.
Published: August 2006

A combined experimental and numerical analysis has been carried out to study the behavior of a bubble under a horizontal heated surface. In this configuration, the interaction between buoyancy and surface tension driven convection produces complex fluid dynamic structures. An instability occurs in the form of an oscillatory three-dimensional fluctuation of the thermal and velocity field when a critical temperature difference is exceeded. The structure of this flow regime has been investigated with transient three-dimensional simulations carried out for normal gravity and zero gravity conditions. The velocity field around the bubble has been experimentally analyzed with a “laser sheet” technique for the flow visualization and a Wollaston prism interferometer has been utilized to capture the oscillatory temperature field. Good correlations are shown between experimental and numerical results.
Singularities on charged viscous droplets
Authors: Betelú S. I. , Fontelos M. A. , Kindelán U. , Vantzos O.
Published: August 2006

We study the evolution of charged droplets of a conducting viscous liquid. The flow is driven by electrostatic repulsion and capillarity. These droplets are known to be linearly unstable when the electric charge is above the Rayleigh critical value. Here, we investigate the nonlinear evolution that develops after the linear regime. Using a boundary element method, we find that a perturbed sphere with critical charge evolves into a fusiform shape with conical tips at time t0, and that the velocity at the tips blows up as (t0−t)α, with α close to −1∕2. In the neighborhood of the singularity, the shape of the surface is self-similar, and the asymptotic angle of the tips is smaller than the opening angle in Taylor cones.
Low shear turbulence structures beneath stress-driven interface with neutral and stable stratification
Authors: Enstad Lars Inge , Nagaosa Ryuichi , Alendal Guttorm
Published: August 2006

This study deals with turbulent flow below a stress-driven interface with stable density stratification, as a simplified configuration of a turbulent flow below a calm gas-liquid interface with wind forcing. A simple shear stress, which is constant in time and uniform at the interface, is enforced, hence only turbulence below the interface is studied. A flat interface is assumed to simplify transport phenomena beneath the interface by limiting the strength of the enforced wind stress and avoiding violent wave motions. A direct numerical simulation technique is employed to obtain three-dimensional turbulence structures below the interface. Results from the present study indicate two major changes of turbulence structures below the sheared interface in the presence of stable density stratification; one is a reduction of the Reynolds stress at the near-interface region, which leads to a coincidental increase of mean velocity gradient. The other effect of stable stratification is the quantitative variation of the surface-streak structures and associated microscale turbulence structures. Examination of the autocorrelation coefficients of the streamwise velocity fluctuations in the subinterface region exhibited that the surface-streak structures in the velocity field are established in both neutral and stably stratified fluid. These streak structures are, however, partially disorganized in the region very close to the interface when strong stable stratification is imposed. The spacing between the streaks tends to decrease with increasing Richardson number in the subinterfacial region −30<x3+<−20, where the disorganization of the streaks is not encountered. A flow visualization technique verifies the establishment of these streaks in every Richardson number case and their partial disorganization under the effect of strong density stratification. A statistical three-dimensional relation between the streaks and the vortical structures are explored by applying a two-point correlation technique to instantaneous turbulent flow realizations. The presence of a counter-rotating vortex pair below the high-momentum fluid at the interface can be found in these examinations. Such presence of the counter-rotating vortex pair are confirmed by the visualization of the vortical structures in instantaneous turbulent flow realizations, whose three-dimensional shape is rather a hairpin-like configuration than two separated vortex tubes.
Quantum energy inequalities and local covariance. I. Globally hyperbolic spacetimes
Authors: Fewster Christopher J. , Pfenning Michael J.
Published: August 2006

We begin a systematic study of quantum energy inequalities (QEIs) in relation to local covariance. We define notions of locally covariant QEIs of both “absolute” and “difference” types and show that existing QEIs satisfy these conditions. Local covariance permits us to place constraints on the renormalized stress-energy tensor in one spacetime using QEIs derived in another, in subregions where the two spacetimes are isometric. This is of particular utility where one of the two spacetimes exhibits a high degree of symmetry and the QEIs are available in simple closed form. Various general applications are presented, including a priori constraints (depending only on geometric quantities) on the ground-state energy density in a static spacetime containing locally Minkowskian regions. In addition, we present a number of concrete calculations in both two and four dimensions that demonstrate the consistency of our bounds with various known ground- and thermal-state energy densities. Examples considered include the Rindler and Misner spacetimes, and spacetimes with toroidal spatial sections. In this paper we confine the discussion to globally hyperbolic spacetimes; subsequent papers will also discuss spacetimes with boundary and other related issues.
Electrical detection of oscillations in microcantilevers and nanocantilevers
Authors: Gaillard J. , Skove M. J. , Ciocan R. , Rao A. M.
Published: August 2006

Precise determination of the resonant frequency, phase, and quality factor in micromechanical and nanomechanical oscillators would permit, among other things, (i) the detection of trace amounts of adsorbed molecules through a shift in the resonant frequency, and (ii) pressure variations in the environment which affect the mechanical damping of the oscillator. The major difficulty in making these measurements in many cases is the ancillary equipment such as lasers or high magnetic fields that must be used. Being able to make precise measurements with a fully electrical actuation and detection method would greatly extend the usefulness of these oscillators. Detecting the oscillation through changes in the capacitance between the oscillator and a counter electrode is difficult because the static capacitance between them as well as the parasitic capacitance of the rest of the circuitry overwhelm the detection. We have found that the charge on a microcantilever or nanocantilever when driven by a nearby counter electrode contains higher harmonics of the driving signal with appreciable amplitude. This allows detection at frequencies well removed from the driving frequency, which increases the signal to background ratio by approximately three orders of magnitude. With this method, we show clear electrical detection of mechanical oscillations in ambient conditions for two systems: Si-based microcantilevers and multiwalled carbon nanotube based nanocantilevers.
Effects of the frequency detuning in Raman backscattering of infinitely long laser pulses in plasmas
Authors: Hur Min Sup , Hwang Ilmoon , Jang Hyo Jae , Suk Hyyong
Published: August 2006

Raman backscattering (RBS) in an infinite homogeneous laser-plasma system was investigated with the three-wave fluid model and averaged particle-in-cell (aPIC) simulations in the nonrelativistic and low temperature regime. It was found that the periodic boundary condition for the electrostatic potential, which is commonly used in an infinite homogeneous plasma, induces a numerical frequency shift of the plasma wave. The initial frequency detuning between the three waves is modified by the frequency shift, leading to a significantly wrong result in the RBS system. An alternative boundary condition based on the Maxwell equation is presented. The aPIC simulations with the modified boundary condition show that the pump depletion level depends sensitively on the frequency mismatch between the three waves. This sensitivity is closely related with the erroneous RBS: the numerical frequency shift is very minor (a few percent of the plasma frequency or less than that) but RBS can be greatly affected even by such a small frequency change. Analytic formulas for the pump depletion time and level is derived and compared to the aPIC simulations with the modified boundary condition, showing an excellent agreement.
Properties of energetic-particle continuum modes destabilized by energetic ions with beam-like velocity distributions
Authors: Todo Y.
Published: August 2006

Properties of energetic-particle continuum modes (EPMs) destabilized by energetic ions in tokamak plasmas were investigated using a hybrid simulation code for magnetohydrodynamics and energetic particles. The energetic ions are assumed to have beam-like velocity distributions for the purpose of clarifying the dependence on energetic ion velocity. It was found that for beam velocities lower than the Alfvén velocity, the unstable modes are EPMs while the toroidal Alfvén eigenmodes are unstable for the beam velocities well above the Alfvén velocity. The EPMs destabilized by the copassing energetic ions and those destabilized by the counterpassing energetic ions differ in primary poloidal harmonics and spatial locations. The frequencies of the EPMs are located close to the shear Alfvén continuous spectrum when they are compared at the spatial peak locations of the primary poloidal harmonic or compared at the spatial tails if the primary poloidal harmonic is m=1. The frequencies of the EPMs were carefully compared with the energetic-ion orbital frequencies. It was found that the frequencies of the EPMs are in good agreement with the energetic-ion orbital frequencies with a correction for the toroidal circulation frequency. This demonstrates that the energetic-ion orbital frequency determines the EPM frequency.
Suppression of phosphorus diffusion by carbon co-implantation
Authors: Pawlak B. J. , Duffy R. , Janssens T. , Vandervorst W. , Felch S. B. , Collart E. J. H. , Cowern N. E. B.
Published: August 2006

The impact of Si interstitial (Sii) flux suppression on the formation of P junctions by rapid thermal annealing (RTA) is demonstrated. Here we investigate the role of amorphization coupled with C co-implantation on P diffusion and its activation. From experiments on C co-implants in a-Si versus c-Si, we conclude that only a small fraction of C interacts with Si interstitials (Sii). We have demonstrated that optimization of implants followed by spike RTA yields extensions suitable for gate lengths of 30nm, with vertical depth Xj=20nm (taken at 5×1018at.∕cm3), abruptness of 3nm/decade, and Rs=326Ω/◻.
Interface circuits for quartz crystal sensors in scanning probe microscopy applications
Authors: Jersch Johann , Maletzky Tobias , Fuchs Harald
Published: August 2006

Complementary to industrial cantilever based force sensors in scanning probe microscopy (SPM), symmetrical quartz crystal resonators (QCRs), e.g., tuning fork, trident tuning fork, and needle quartz sensors, are of great interest. A self-excitation scheme with QCR is particularly promising and allows the development of cheap SPM heads with excellent characteristics. We have developed a high performance electronic interface based on an amplitude controlled oscillator and a phase-locked loop frequency demodulator applicable for QCR with frequencies from 10 up to 10MHz. The oscillation amplitude of the sensing tip can be set from thermal noise level up to amplitudes of a tenth of nanometers. The device is small, cheap, and highly sensitive in amplitude and frequency measurements. Important features of the design are grounded QCR, parasitic capacity compensation, bridge schematic, and high temperature stability. Characteristic experimental data of the device and its operation in combination with a commercial SPM and a homemade scanning near-field optical microscope are reported. By using the 1MHz needle quartz resonator with a standard atomic force microscope tip attached, atomic scale resolution in ambient conditions is achieved. Furthermore, reproducible measurements on very soft materials (Langmuir-Blodgett layers) with a very stiff needle quartz (∼400000N∕m) are possible.
Electroplated mounting of diamond anvils for use in cryogenic systems
Authors: Pugh E. , Haselwimmer R. K. W.
Published: August 2006

The mounting of diamonds using the electroplated deposition of copper was originally developed to hold diamonds in place during polishing. This article describes the extension and application of this method for the mounting of diamonds inside diamond anvil cells. The novel method described, unlike more traditional gluing or clamping methods, can withstand both continual thermal cycling and provide a small profile such that it can be used in miniature cells to permit ample space for fitting electrical feed throughs or external coils around the anvils. The method is developed such that it can be used to attach the diamond to nonmetallic backing plates such as sapphire. Details of precautions to reduce the production of eddy currents in the deposited copper when performing ac-susceptibility measurements are also described.
On the tunnel injection of excitons and free carriers from In0.53Ga0.47As∕In0.53Ga0.23Al0.24As quantum well to InAs∕In0.53Ga0.23Al0.24As quantum dashes
Authors: Podemski P. , Kudrawiec R. , Misiewicz J. , Somers A. , Reithmaier J. P. , Forchel A.
Published: August 2006

The authors investigate the efficiency of exciton and free carrier injections from quantum well (QW) to quantum dashes (QDashes) in tunnel-injection structures composed of In0.53Ga0.47As∕In0.53Ga0.23Al0.24As QW and InAs∕In0.53Ga0.23Al0.24As QDashes with ground state transitions separated by the energy close to the energy of LO phonon. As far as the thermal energy is smaller than the binding energy of QW excitons, almost all of the carriers created in QW tunnel to QDash. The injection process is much less efficient for free carriers because the energy difference between energy levels in QW and QDashes is not favorable for tunneling of electrons and holes separately.
Spin-wave interference
Authors: Choi Sangkook , Lee Ki-Suk , Kim Sang-Koog
Published: August 2006

Spin-wave interference is demonstrated in the micromagnetic modeling of a specially designed geometry made of variously shaped magnetic thin-film waveguides. When spin waves are diffracted through two separate openings, corresponding to the two pinholes in the second screen of Young’s apparatus, they interfere constructively or destructively in a magnetic medium, thereby showing distinct interference patterns. Furthermore, the radiation, propagation, transmission, and dispersion behaviors of spin waves as well as the filtering of their lower frequencies are investigated in the present modeling study. These results directly confirm not only the wave characteristics of spin waves traveling at ultrafast speeds in variously shaped magnetic waveguides but also their interference effect, that is similar to that observed in well-known Young’s double slit experiment with light.