bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Southern Hemisphere Radiosonde and Lims Temperatures At 100 Mb
Authors: Miles T. , Grose W. L. , Russell J. M. , Remsberg E. E.
Published: July 2010

Radiosonde and satellite‐derived 100 mb temperatures over New Zealand at 12 GMT are compared for the 1978‐79 summer. the satellite measurements are made by the Nimbus‐7 Limb Infrared Monitor of the Stratosphere (LIMS) instrument. the co‐located LIMS temperature information consists of synoptically‐mapped values (for 12 GMT), as well as the primary nighttime orbital retrievals valid at ∼1030 GMT.

The radiosonde time series of temperature is dominated by temporal fluctuations associated mainly with the eastward passage of waves which have characteristic periods of 4‐5 and 11‐12 days and peak‐to‐peak amplitudes of 10‐15 K. In agreement with previous (northern hemisphere) 100 mb LIMS validation studies, the New Zealand orbital LIMS temperatures for 100 mb compare quite favourably with the ‘ground‐truth’ radiosonde measurements (r.m.s. difference of ∼1.6K). the corresponding LIMS‐mapped temperature time series is also found to exhibit quite close agreement, in terms of temporal phase, with the radiosonde information. However, it is shown that the LIMS‐mapped temperature fluctuations suffer from a noticeable attenuation in amplitude (approaching 50% for higher frequency fluctuations), which will therefore impact on the accuracy of LIMS‐derived estimates of dynamical quantities such as wind velocity and relative vorticity in the lower stratosphere.
Uncertainty dynamics and predictability in chaotic systems
Authors: Smith L. A. , Ziehmann C. , Fraedrich K.
Published: July 2010

An initial uncertainty in the state of a chaotic system is expected to grow even under a perfect model; the dynamics of this uncertainty during the early stages of its evolution are investigated. A variety of ‘error growth’ statistics are contrasted, illustrating their relative strengths when applied to chaotic systems, all within a perfect‐model scenario. A procedure is introduced which can establish the existence of regions of a strange attractor within which all infinitesimal uncertainties decrease with time. It is proven that such regions exist in the Lorenz attractor, and a number of previous numerical observations are interpreted in the light of this result; similar regions of decreasing uncertainty exist in the Ikeda attractor. It is proven that no such regions exist in either the Rössler system or the Moore‐Spiegel system. Numerically, strange attractors in each of these systems are observed to sample regions of state space where the Jacobians have eigenvalues with negative real parts, yet when the Jacobians are not normal matrices this does not guarantee that uncertainties will decrease. Discussions of predictability often focus on the evolution of infinitesimal uncertainties; clearly, as long as an uncertainty remains infinitesimal it cannot pose a limit to predictability. to reflect realistic boundaries, any proposed ‘limit of predictability’ must be defined with respect to the nonlinear behaviour of perfect ensembles. Such limits may vary significantly with the initial state of the system, the accuracy of the observations, and the aim of the forecaster. Perfect‐model analogues of operational weather forecasting ensemble schemes with finite initial uncertainties are contrasted both with perfect ensembles and uncertainty statistics based upon the dynamics infinitesimal uncertainties.
Observations of subtropical air in the european mid‐latitude lower stratosphere
Authors: O'Connor F. M. , Vaughan G. , De Backer H.
Published: July 2010

Evidence of two wave‐breaking events, during which subtropical air was transported into the northern mid latitudes, is presented. the first event took place in January 1997 when ozone mixing ratios of the order of 120 parts per billion (109) by volume (p.p.b.v.) were measured in the lower stratosphere above Aberystwyth (52.4°N, 4.1°W). the amount of subtropical air involved was 13 × 1014 kg. A second, more dramatic, wavebreaking event took place in March 1997 involving 36 × 1014 kg of air. This case contained a region with potential vorticity ⩽ 2 potential vorticity units (1 PVU=1 × 10‐6 K kg‐1m2s‐1), consistent with ozone mixing ratios of 80 p.p.b.v. observed at Aberystwyth at 365 K. Trajectory analysis showed that this air was advected northwards from near the subtropical tropopause. the extent to which irreversible transport into the mid‐latitude lower stratosphere followed both events is evaluated using trajectory analysis and potential‐vorticity evolution.
Parametrization of effective sizes of cirrus‐cloud particles and its verification against observations
Authors: Sun Zhian , Rikus Lawrie
Published: July 2010

A simplified parametrization of effective sizes of cirrus‐cloud particles is developed in terms of the ice‐water content and the cloud temperature based on some earlier studies. the effective particle sizes of the cirrus clouds determined using the simplified parametrization are compared with the results determined from observations. the results are generally encouraging.

The simplified parametrization is further tested by incorporating it into a new ice‐cloud optical‐property parametrization scheme and performing radiative‐transfer calculations. the results show that this scheme in conjunction with the ice‐cloud optical‐properties scheme can generate a reasonably good estimate of cirrus‐cloud radiative properties compared with the observations.
Cloud‐to‐ground lightning activity and radar observations of storms in the pyrénées range area
Authors: Molinie G. , Soula S. , Chauzy S.
Published: July 2010

This paper analyses radar observations and cloud‐to‐ground (CG) lightning flash activity of several thunderstorms occurring over the Pyrénées range during the night of 23‐24 August 1993 and the afternoon of 24 August 1993. the available data consisted of the European meteorological bulletin, the plan position indicator radar scans at three elevations performed by the 5.5 cm wavelength Rodin radar of Toulouse, and the characteristics of the CG lightning strikes.

The first thunderclouds began to develop at around 2200 UTC 23 August. Up to 0100 UTC 24 August, we observed three isolated convective cells. We also studied a mesoscale convective system (MCS) occurring during the afternoon of 24 August, and chose to investigate three convective cells embedded within it. These different thunderclouds developed over the Spanish side of the Pyrénées and moved north‐eastwards over the mountains. the locations of CG flashes in relation to the reflectivity fields revealed two kinds of CG lightning activity: flashes associated with intense rainfall, and those located in stratiform cloud areas far from the intense precipitating zone. the flash density was larger within the first type and the positive flash proportion was larger in the second type. the amount of large precipitating particles was characterized by the area A(τ) covered by reflectivities larger than τ dBZ, with τ taken as 33 dBZ. the study of the time evolution of A (33) at three altitudes showed that, for the lightning activity associated with intense rainfall, strong reflectivities at high altitude (4.5 km, and sometimes 7.5 km) coincided with large lightning flash rates, though it was the time evolution of the vertical profile of the area covered by precipitation that drove the CG lightning flash rate (or vice‐versa). the maximum flash rate coincided with the fall of large precipitating particles. Furthermore, a time lag was observed at the ground between the lightning flash rate and the rainfall rate. the time evolutions of the flash rate and A (τ) at the lowest elevation of the radar beam (0.6°) confirmed this delay. the correlation coefficient between these two parameters for the isolated convective cells reached 0.81 in the best case. the correlation between the lightning activity and precipitation of the whole MCS was less good but, nevertheless, the volume of precipitation per CG lightning flash was of the same order of magnitude for all the cells or MCSs observed. It ranged from 3.2 × 103 to 46.8 × 103 m3 flash‐1, in accordance with the results of other authors.
Atmospheric and surface variations during westerly wind bursts in the tropical western pacific
Authors: Fasullo John , Webster Peter J.
Published: July 2010

An analysis is made of variations in both the surface energy balance and the regional atmospheric dynamic and thermal structure during 44 westerly wind bursts (WWBs) in the western equatorial Pacific Ocean from 1979 to 1995. The study assesses winds, convective available potential energy, cloud properties, precipitation, surface temperature, and surface heat flux while distinguishing between brief (5–25 day periodicity) and sustained (30–90 day) WWBs. Datasets used in the study include fields from the NCEP/NCAR and ECMWF re‐analyses, and satellite retrievals of clouds (ISCPP), precipitation (MSU), moisture (TOVS), and surface solar flux.

Both brief and sustained WWBs, by definition, experience strong low‐level westerly winds that typically induce an increased surface latent‐heat flux of approximately 30 W m−2. Enhanced cloud thickness, precipitation, and upper tropospheric easterly wind anomalies accompany surface westerly winds, though maxima in winds lag those in clouds and precipitation by about one day for brief WWBs and four days for sustained events. WWBs of both types experience strong seasonality, occurring frequently in all seasons except boreal summer.

Important distinctions between brief and sustained WWBs can also be made. Westerly anomalies typically extend above 200 hPa during brief WWBs but are generally confined to the lower troposphere (below 400 hPa) for sustained events. Sustained WWBs are also preceded by a quiescent period of reduced cloud thickness and surface winds that is accompanied by strong incident solar flux. Convective instability, as judged by a variety of techniques, increases by approximately 30% during this quiescent period. Brief WWBs do not include the precursory surface warming or convective destabilization of sustained WWBs. Notwithstanding the warming episodes before the events, sustained WWBs are associated with a net surface cooling approximately 40% larger than brief WWBs.

The relationship between brief and sustained WWBs and the phase of the Madden‐Julian Oscillation (MJO) (as judged from outgoing long‐wave radiation) is also examined. Results support the classification of events as ‘brief’ and ‘sustained’ as used in this study, with brief WWBs occurring frequently during both wet and dry phases of the MJO, while sustained WWBs occur uniquely during the MJO wet phase. The association of brief and sustained WWBs with the MJO is shown to be independent of the El Niiio Southern Oscillation phase. It is therefore proposed that some, but not all, WWBs may be viewed as the surface signature of the MJO and that the mechanisms responsible for the MJO play an integral role in the formation and sustenance of sustained WWBs.
Dissipative heating in climate models
Authors: Fiedler B. H.
Published: July 2010

The various strategies towards dissipative heating in meteorological models are reviewed. The strategies are implicit formulations, explicit formulations, and exclusion. A thermodynamic formulation based on dry static energy, which has long been used in hydrostatic models, implicitly includes dissipative heating. Many modem non‐hydrostatic mesoscale models, being based on potential temperature, do not include any dissipative heating. The National Center for Atmospheric Research community climate model (CCM3) explicitly formulates the dissipative heating for the resolved motion, which is based upon potential temperature, but, uses the implicit formulation for the sub‐grid motion.

Those who want to use the mesoscale‐model formulation as a cloud‐resolving climate model are advised to consider the effect of dissipative heating. We show a dry radiative‐convective model, formulated without dissipative heating, in which climate equilibrium occurs with a net inward radiative flux of about 18 W m−2at the top of the atmosphere, and a surface temperature that is 8 K too low.
On the accuracy of the semi‐geostrophic approximation
Authors: Cullen M. J. P.
Published: July 2010

The semi‐geostrophic model has been widely used to understand atmospheric flows such as fronts and developing cyclones. However, there have been a number of demonstrations of its lack of accuracy. This paper presents theory and computations to demonstrate that the semi‐geostrophic model is an accurate approximation to the primitive equations either on horizontal scales larger than the Rossby radius of deformation or when the ratio of horizontal to vertical scales is greater than f/N.
The ECMWF operational implementation of four‐dimensional variational assimilation. II: Experimental results with improved physics
Authors: Mahfouf J.‐F. , Rabier F.
Published: July 2010

A comprehensive set of physical parametrizations has been linearized for use in the European Centre for Medium‐Range Weather Forecasts (ECMWF's) incremental four‐dimensional variational (4D‐Var) system described in Part I. The following processes are represented: vertical diffusion, subgrid‐scale orographic effects, large‐scale precipitation, deep moist convection and long‐wave radiation. The tangent‐linear approximation is examined for finite‐size perturbations. Significant improvements are illustrated for surface wind and specific humidity with respect to a simplified vertical diffusion scheme. Singular vectors computed over 6 hours (compatible with the 4D‐Var assimilation window) have lower amplification rates when the improved physical package is included, due to a more realistic description of dissipative processes, even though latent‐heat release contributes to amplify the potential energy of perturbations in rainy areas. A direct consequence is a larger value of the observation term of the cost‐function at the end of the minimization process when improved physics is included in 4D‐Var. However, the larger departure of the analysis state from observations in the lower‐resolution inner‐loop is in better agreement with the behaviour of the full nonlinear model at high resolution. More precisely, the improved physics produces smaller discontinuities in the value of the cost‐function when going from low to high resolution. In order to reduce the computational cost of the linear physics, a new configuration of the incremental 4D‐Var system using two outer‐loops is defined. In a first outer‐loop, a minimization is performed at low resolution with simplified physics (50 iterations), while in the second loop a second minimization is performed with improved physics (20 iterations) after an update of the model trajectory at high resolution. In this configuration the extra cost of the physics is only 25%, and results from a 2‐week assimilation period show positive impacts in terms of quality of the forecasts in the Tropics (reduced spin‐down of precipitation, lower root‐mean‐square errors in wind scores). This 4D‐Var configuration with improved physics and two outer‐loops was implemented operationally at ECMWF in November 1997.
The vertical resolution sensitivity of simulated equilibrium temperature and water‐vapour profiles
Authors: Tompkins Adrian. M. , Emanuel Kerry. A.
Published: July 2010

Variability of atmospheric water vapour is the most important climate feedback in present climate models. Thus, it is of crucial importance to understand the sensitivity of water vapour to model attributes, such as physical parametrizations and resolution. Here we attempt to determine the minimum vertical resolution necessary for accurate prediction of water vapour.

To address this issue, we have run two single‐column models to tropical radiative—convective equilibrium states and have examined the sensitivity of the equilibrium profiles to vertical resolution. Both column models produce reasonable equilibrium states of temperature and moisture.

Convergence of the profiles was achieved in both models using a uniform vertical resolution of around 25 hPa. Coarser resolution leads to significant errors in both the water vapour and temperature profiles, with a resolution of 100 hPa proving completely inadequate. However, fixing the boundary‐layer resolution and altering only the free‐tropospheric resolution significantly reduces sensitivity to vertical resolution in one of the column models, in both water and temperature, highlighting the importance of resolving boundary‐layer processes. Additional experiments show that the height of the simulated tropopause is sensitive to upper‐tropospheric vertical resolution.

At resolutions higher than 33 hPa, one of the models developed a high degree of vertical structure in the vapour profile, resulting directly from the complex array of microphysical processes included in the stratiform cloud parametrization, some of which were only resolved at high resolutions. This structure was completely absent at lower resolutions, casting some doubt on the approach of using relatively complicated cloud schemes at low vertical resolutions.
On the wave‐activity invariants and stability of the two‐layer shallow‐water semi‐geostrophic model
Authors: Ren Shuzhan
Published: July 2010

Although the two‐layer shallow‐water semi‐geostrophic (TLSWSG) model has been proven to be an important tool for the investigation of the dynamics of anisotropic and baroclinic flow in frontal zones, its general instability mechanism, however, has not been well understood. In light of recent work on the stability of the one‐layer SWSG model, this issue is re‐examined in this paper by extending a body of well developed theorems in the two‐layer quasi‐geostrophic (QG) model to the TLSWSG model. The generalized linearized TLSWSG model equations with respect to a parallel basic state are presented first. Conservation equations for two small‐amplitude wave‐activity invariants analogous to pseudo‐momentum and pseudo‐energy densities in QG dynamics are derived and then used to examine the stability of a parallel basic state. It is found that the TLSWSG model possesses two kinds of stability conditions: Arnold's first stability condition in the interior, plus conditions on lateral boundaries, and Arnold's second stability condition. In contrast to previous work, Ripa's ‘subsonic’ condition \documentclass{article}\pagestyle{empty}\begin{document}$ \[\left({\left({U_{G1},U_{G2} } \right)\max < \sum\nolimits_{j = 1}^2 {\left({{1 \mathord{\left/ {\vphantom {1 {cj}}} \right. \kern-\nulldelimiterspace} {cj}}} \right)^{ - 1} } } \right) \] $\end{document}, where UG1 and UG2 are basic flows at two levels and Cj is the phase speed of gravity waves at the jth level) is found to be unnecessary, and the underlying physical reasons, associated with the coastal Kelvin waves in the model, are given. It is also found that the phase speed of unstable normal‐mode disturbances of slow motion satisfies Howard's semi‐circle theorem.

The energy—Casimir method is applied to derive small‐ and finite‐amplitude wave‐activity invariants and corresponding stability criteria for non‐parallel basic states. It turns out that the stability criteria for non‐parallel basic states include not only those for parallel basic states but also conditions associated with the anisotropy of basic flow. The nonlinear stability analyses in this work help us to understand the failure of the energy—Casimir method in deriving finite‐amplitude stability criteria in the continuously stratified semi‐geostrophic model.
Some field experiments on the interaction of plumes from two sources
Authors: Davies B. M. , Jones C. D. , Manning A. J. , Thomson D. J.
Published: July 2010

Some experiments to measure concentration fluctuations downwind of two tracer sources in the atmospheric surface layer are described and the results presented. Fast response detectors were used. The sources were at a height of 4 m and the experiments were restricted to short ranges where the flow and turbulence can be assumed to be approximately homogeneous for the purpose of predicting the dispersion. The results are analysed to show the downwind evolution of the intensity of fluctuations for each source separately and to show how the correlation between the concentrations from the two sources varies with downwind distance and source separation. The variation of the intensity of fluctuations and the correlation with averaging time is also explored. Results support the idea of a universal behaviour when suitably scaled.
A method for estimating the analysis error variance in a physical space data assimilation system
Authors: Rushøjgaard Lars Peter
Published: July 2010

The error variance of a meteorological analysis is an important quantity, both as a measure of confidence in the analysed product, and as an initial condition for the forecast error variance in a cycling data assimilation system. Modem assimilation systems that rely on global solutions of the analysis equations typically do not include an estimate of this quantity, even though the equation for the full analysis error covariance matrix is well‐known. The reason is that this equation is far too costly to implement directly. In this article we analyse the analysis error covariance equation of the Kalman filter, and we propose a computationally efficient method for estimating the analysis error variance, i.e. the diagonal elements of the covariance matrix. The estimate is shown to be conservative in the sense that the analysis error variance is overestimated everywhere. We illustrate the performance of the method in the context of simple two‐dimensional analysis experiments as well as in a global, three‐dimensional ozone data assimilation system. These experiments show that both quantitatively and qualitatively the method captures the main features of the variance calculated by the full covariance equation at a small fraction of the cost.
Observation and background adjoint sensitivity in the adaptive observation‐targeting problem
Authors: Baker Nancy L. , Daley Roger
Published: July 2010

Recent observation‐targeting field experiments, such as the Fronts and Atlantic Storm‐Track Experiment (FASTEX) and the NORth Pacific Experiment (NORPEX), have demonstrated that by using objective adjoint techniques it is possible, in advance, to identify regions of the atmosphere where forecast‐error growth in numerical forecast models is maximally sensitive to the error in the initial conditions. 'Qpically, such techniques produce a field of the sensitivity of some aspect of the forecast to the analysis field. This analysis sensitivity field is then used to identify promising targets for the deployment of additional observations during the flight‐planning phase of field experiments. While FASTEX and, particularly. NORPEX had a number of successful ‘hits’, where the addition of dropsondes reduced the forecast error, there were also failures.

None of the objective techniques have involved any consideration of the characteristics of the data‐assimilation systems used in the analysis of the targeted observations. In particular, the interaction with the background field, interactions with other observations, and the background‐ and observationerror characteristics have been ignored. This can lead to potential mis‐sampling, conflict with other observations, and inefficient use of aircraft and expendables.

In this study, the adjoint of a simplified data‐assimilation system is used to determine directly the sensitivity of the forecast aspect to the observations and the background field. The procedure is illustrated by using simplified linear contexts such as the one‐ and two‐dimensional horizontal univariate problem and the one‐dimensional direct radiance assimilation problem. Adaptive targeting tools, such as a single‐observation sensitivity map and a marginal observation sensitivity vector, are devised and tested. The possibility of determining when the forecast would be sensitive to the background field and/or the observations is demonstrated. Such dependencies are shown to be a function of the specified observation‐ and background‐error variances, the characteristic scales of analysis sensitivity vector and background‐error correlations, and the properties of forward (observation) operators.

Although the present experiments concerned simplified assimilation systems and observation networks, extension of the technique to real situations is quite feasible. Obtaining the adjoint of a full three‐dimensional variational assimilation system is straightforward; moreover, the target areas are small and contain relatively few observations so the computational requirements are modest.

Finally, the data‐assimilation adjoint theory can be used for a posteriori assessment of those sources of forecast error which are due to errors in the initial analysis.
The use of tovs observations for the identification of tropopause‐level thermal anomalies
Authors: Fourrié Nadia , Claud Chantal , Donnadille Jérǒme , Cammas Jean‐Pierre , Pouponneau Béatrice , Scott Noelle
Published: July 2010

The evolution of tropopause‐level thermal patterns is generally not well represented by the conventional observational network, especially over the oceans. An alternative is provided by satellite observations which are global and frequent. In particular, from the TIROS‐N (Television Infra‐Red Observation Satellite) Operational Vertical Sounder (TOVS) which flies on‐board National Oceanic and Atmospheric Administration satellites, an estimate of the temperature of the lower stratosphere (TLS) can be derived using the Improved Initialization Inversion algorithm. In this study, the degree of reliability of TLS for describing tropopause‐level thermal structures and variations is examined. For three intensive observation periods (16, 17 and 18) of the Fronts and Atlantic Storm‐Track Experiment, conducted in January and February 1997 over the North Atlantic Ocean, TLS fields are described; their advantage, compared with the use of raw microwave data, is illustrated; TLS variations are also studied in connection with other dynamical variables which can be obtained by the French Action de Recherche Petite Echelle Grande Echelle operational model analysis. Finally, the suitability of TLS as a possible forecasting aid over mid‐oceanic regions is promoted.
Properties of the arctic tropopause
Authors: Highwood E. J. , Hoskins B. J. , Berrisford P.
Published: July 2010

A climatology of Arctic tropopause properties is derived using European Centre for Medium‐Range Weather Forecasts Re‐analyses, and is shown to be consistent with that from the Historical Arctic Radiosonde Archive. It is demonstrated that the thermal tropopause is generally easy to define from the temperature profile, even in the polar night, in contrast with the situation in Antarctic winter. In winter, the tropopause tends to have higher pressure and temperature in the western hemisphere and lower values in the eastern hemisphere. In summer the situation is more zonally symmetric with the higher pressure and temperature tropopause region near the pole. Strong annual cycles are seen in both temperature and pressure. these cycles being out of phase temporally. It is hypothesized that the tropopause temperature is largely determined by the approximately isothermal lower‐stratospheric temperature, while the pressure is more strongly influenced by changes in the tropospheric lapse rate due to dynamical mechanisms. The multi‐decade radiosonde dataset (1965–1990) shows some evidence of a long‐term trend in tropopause properties. The wintertime tropopause pressure has decreased by approximately 14 mb per decade, while that in other seasons has decreased by around 5 mb per decade. The tropopause temperature only shows a significant trend during winter, having decreased by 1.6 K per decade since 1965. These changes are discussed in relation to changes in ozone and greenhouse gases, and the strength of the stratospheric vortex. In particular, the winter tropopause properties appear to be strongly correlated with the Arctic Oscillation Index.
Surface resistance in atmospheric flow
Authors: Sutcliffe R. C.
Published: July 2010

The formula for surface resistance to atmospheric flow, F = ρκV2s, where Vs is the velocity of the surface wind, ρ the density, and κ a non‐dimensional constant, was proposed by G. I. Taylor, on an analogy with flow in pipes. In pipes, the value of κ was 0.004, and Taylor gave a mean value of 0.0025 for κ in the case of flow of air over the ground. In this paper the value of κ was deduced from actual observed distributions of wind velocity at different heights, obtained by pilot balloons, no assumption being made as to the nature of eddy viscosity. The mean value of κ so deduced is 0.006 over land, and 0.0004 over the sea.
Sonographic description and classification of tendinous involvement in relation to tophi in chronic tophaceous gout
Authors: de Ávila Fernandes Eloy , Sandim Gabriel B. , Mitraud Sônia A. V. , Kubota Edson S. , Ferrari Antonio J. L. , Fernandes Artur R. C.
Published: July 2010

Objective

To describe and classify the varied ultrasound features of tendinous involvement in relation to tophi in chronic tophaceous gout so that they are better recognised.

Methods

Ultrasound images of 138 affected areas from 31 patients with chronic tophaceous gout were analysed using high-quality broadband linear transducers. The relationship between tendon and tophi was classified, and the inter-observer agreement regarding classification was analysed.

Results

Tophi envelopment in the tendon was the most frequent characteristic (45%) followed by no relationship between tophi and tendon (41%), tophi at the insertion site of the tendon (7%), extrinsic compression (6%) and tophi within the tendon (1%). The inter-observer concordance on classification of the relationship between tophi and tendon was measured using McNemar’s test withP < 0.001 (χ2 = 30.0, degree of freedom = 9) and kappa test = 0.627 (P < 0.001), indicating substantial inter-observer concordance.

Conclusion

Tophi generally envelope the tendon or there is no relationship between them. Tophi can also be found at the insertion site of the tendon, cause extrinsic compression or be located inside the tendon. There is substantial inter-observer agreement for ultrasound classification of tendon involvement by tophi. This study contributes to diagnostic elucidation and shows the diverse characteristic forms of tendon involvement by tophi.
Substance use among middle school students: Associations with self‐rated and peer‐nominated popularity
Authors: Tucker Joan S. , Green Harold D. , Zhou Annie J. , Miles Jeremy N.V. , Shih Regina A. , D’Amico Elizabeth J.
Published: July 2010

Associations of popularity with adolescent substance use were examined among 1793 6–8th grade students who completed an in‐school survey. Popularity was assessed through both self‐ratings and peer nominations. Students who scored higher on either measure of popularity were more likely to be lifetime cigarette smokers, drinkers, and marijuana users, as well as past month drinkers. Self‐rated popularity was positively associated with past month marijuana use and heavy drinking, and peer‐nominated popularity showed a quadratic association with past month heavy drinking. These results extend previous work and highlight that popularity, whether based on self‐perceptions or peer friendship nominations, is a risk factor for substance use during middle school. Given the substantial increase in peer influence during early adolescence, prevention program effectiveness may be enhanced by addressing popularity as a risk factor for substance use or working with popular students to be peer leaders to influence social norms and promote healthier choices.
Adolescents and youth in developing countries: Health and development issues in context
Authors: Fatusi Adesegun O. , Hindin Michelle J.
Published: July 2010

Adolescence is a period of transition, marked by physical, psychological, and cognitive changes underpin by biological factors. Today's generation of young people – the largest in history – is approaching adulthood in a world vastly different from previous generations; AIDS, globalisation, urbanisation, electronic communication, migration, and economic challenges have radically transformed the landscape. Transition to productive and healthy adults is further shaped by societal context, including gender and socialisation process. With the evidence that young people are not as healthy as they seem, addressing the health and development issues of young people, more than ever before, need concerted and holistic approach. Such approach must take the entire lifecycle of the young person as well as the social environment into context. This is particularly critical in developing countries, where three major factors converge – comparatively higher proportion of young people in the population, disproportionately high burden of youth‐related health problems, and greater resources challenge.
Brief report: Do delinquency and community violence exposure explain internalizing problems in early adolescent gang members?
Authors: Madan Anjana , Mrug Sylvie , Windle Michael
Published: July 2010

Adolescent gang members are at higher risk for internalizing problems as well as exposure to community violence and delinquency. This study examined whether gang membership in early adolescence is associated with internalizing problems (depression, anxiety, and suicidal behavior) and whether these associations are mediated by delinquency and witnessing community violence. In a sample of 589 ethnically diverse early adolescents, gang membership was related to suicidal behavior but not depression or anxiety. Both delinquency and witnessing community violence mediated this association. Professionals working with gang members should assess these youth for suicidal behavior and provide interventions as needed.
Marketing Spending Strategy in Recessions
Authors: Lilien Gary L. , Srinivasan Raji
Published: July 2010

Recessions provide challenges to managers seeking to develop and justify an appropriate level of market-facing activity. The literature on the topic offers limited guidance on what strategy is most appropriate. We briefly review the literature on the topic and report on recent results that show (a) that R&D spending by B2BGoods firms and B2BServices firms in recessions increases both profits and stock returns, while advertising spending decreases both profits and stock returns; (b) for B2CServices firms, both R&D and advertising spending in recessions increases profits and stock returns and (c) for B2CGoods firms, R&D spending in recessions increases profits and stock returns, while advertising spending increases profits but decreases stock returns. Further, these effects are either strengthened or weakened depending on the firm's market share and financial leverage.
The Management of Voiding Dysfunction following Mid Urethral Tape Insertion
Authors: Dasgupta Jaydip , Goddard Jonathan C. , Mayne Christopher J. , Tincello Douglas G.
Published: July 2010

Objective:

No standard regimen has been established for the management of postoperative voiding dysfunction following TVT insertion. This study was designed to compare two different strategies for management of this problem.

Methods:

This is a retrospective study of women operated on within a tertiary referral unit. Two cohorts were identified: those managed by clean intermittent self catheterization (CISC) during 2006, and those managed by ‘pull-down’ of tape in the immediate post-operative period during 2007. Specific measurements include number of patients with resumption of normal voiding and time taken for resolution of symptoms. Incidence of tape division, recurrence of stress incontinence and development of overactive bladder (OAB) were also measured.

Results:

The incidence of voiding difficulty following TVT insertion remained the same in 2006 and in 2007. 45.5% of the CISC group resumed normal voiding compared to 100% of the ‘pull-down’ group. The incidence of tape division and reappearance of stress incontinence was 54.5% and 27% respectively in the CISC group compared to none in the ‘pull-down’ group. The CISC group also had higher incidence of OAB.

Conclusions:

Immediate “pull-down” of tape is an effective way of managing voiding dysfunction following TVT with an excellent rate of symptom resolution without any need of further intervention.
Parallel Incisions Procedure for Penile Curvature—Short Term Outcomes
Authors: Chang R.T.M. , Sahai A. , Dickinson I.K.
Published: July 2010

Objective:

A modified corporotomy technique has been developed in order to overcome the problems of previous techniques such as tissue removal, urethral mobilisation, palpable knots, ‘dog ears’ and leakage on testing after repair. Our objective is to describe the technique and review the outcomes in the short term.

Methods:

The procedure involves two transverse parallel incisions at the bite points of Allis forceps used to correct curvature. The intervening tunica is buried, sealing the incision and preventing leakage. The incision is closed with 2–0 Polydioxanone sutures and a single 2–0 Polyglycolic to maintain knot burial. Data were collected retrospectively on all patients undergoing this technique from our department.

Results:

Thirty-two patients underwent daycase surgery. Mean duration of disease was 12.5 months. At three months the cosmetic result was excellent (straight) or good (<20° bend) in 97%. Patient satisfaction was high with 87% being happy with the outcome and 88% able to have pain free intercourse. Complications of note included glans numbness in 1 patient and chronic granuloma related to suture placement requiring excision in 1 patient.

Conclusions:

The modified parallel incisions procedure is easy to perform and is efficacious in the short term with good cosmetic results and high patient satisfaction. Longer term follow-up is planned in a prospective fashion.
Effect of isosorbide mononitrate for cervical ripening before surgical termination of pregnancy in the first trimester
Authors: Phusaanantakul Poonam , Promsonthi Patama , Chanrachakul Boonsri
Published: July 2010

Objective

To evaluate the efficacy of isosorbide mononitrate (IMN) for cervical ripening prior to first trimester surgical termination of pregnancy.

Methods

A prospective, double‐blind, randomized, placebo‐controlled trial. Women scheduled for surgical termination of a nonviable fetus before 12 weeks of gestation from October 2008 to June 2009 were enrolled and randomly assigned to receive either 20 mg vaginally of IMN (n = 24) or a placebo (n = 24) 4 hours before suction evacuation. Cervical dilation before evacuation was assessed with 10‐mm Hegar dilators followed by smaller sizes that were measured until the instrument passed freely through the internal os. Cervical dilation, adverse effects, termination complications, and patient satisfaction were the main outcomes.

Results

Mean cervical dilation was not significantly different between the IMN and placebo groups (6.29 ± 0.99 mm vs 5.71 ± 1.04 mm; P = 0.05). Mean operative time did not differ between the groups (16 ± 0.07 min vs 18 ± 0.06 min; P = 0.55), nor did patient satisfaction measured by visual analogue scale (7.04 ± 1.68 vs 6.54 ± 1.22; P = 0.24).

Conclusion

IMN was comparable to placebo in terms of efficacy and patient satisfaction for cervical priming prior to first‐trimester termination of pregnancy.
Teaching Learning Strategies with a Pedagogical Agent
Authors: Sträfling Nicole , Fleischer Ivonne , Polzer Christin , Leutner Detlev , Krämer Nicole C.
Published: July 2010

Numerous studies have tested the effects of pedagogical agents on learning and the influence of their specific appearance. What has not been analyzed, however, is whether an agent can have indirect effects when it is employed as a tutor for learning strategies rather than directly teaching the relevant learning material. In a between-subjects design (N = 45) we compared two different kinds of pedagogical agents – a cartoon-like rabbit and a realistic anthropomorphic agent – with a control group that was not tutored by an animated agent but was informed by voice only. Results showed no clear advantages for the agents compared to voice-based tutoring with regard to indirect learning effects, but they did demonstrate that the appearance of the agent matters. The rabbit-like agent was not only preferred, but people exposed themselves longer to the tutoring session when the rabbit provided feedback.
Do Pedagogical Agents Facilitate Learner Motivation and Learning Outcomes?
Authors: Domagk Steffi
Published: July 2010

Pedagogical agents – lifelike characters that guide users through multimedia learning environments – are intended to facilitate the learning process. According to social agency theory, the presentation of social cues (the image and voice of the agent) may prime the social interaction schema and cause the learner to deeply process the learning material. Research on pedagogical agents focuses mainly on either the role of the presence of pedagogical agents, by comparing agent and no-agent groups, or on the design of the character, by comparing different agent groups. This article takes a comprehensive view combining both approaches in order to answer the question of how pedagogical agents should be designed so as to promote learner motivation and learning. It is argued that not only the mere presence, but also the valence of the social cues presented plays a decisive role. Two experiments examine the role of the perceived appeal of a pedagogical agent’s appearance and voice. The results of Experiment 1 indicate that pedagogical agents may promote transfer performance, but only if they are appealing in appearance. The mere inclusion of a pedagogical agent yielded no effect on motivation or learning. Experiment 2 suggests that a high appeal of the pedagogical agent’s appearance and voice promoted transfer performance. However, this advantage did not occur when compared to a control group without an agent. The presentation of two unappealing social cues (appearance and voice) even harmed transfer. This result suggests an important modification of social agency theory.
Individual histories and selection in heterogeneous populations
Authors: Leibler Stanislas , Kussell Edo
Published: July 2010

The strength of selection in populations has traditionally been inferred by measuring changes in bulk population parameters, such as mean reproductive rates. Untangling the effect of selection from other factors, such as specific responses to environmental fluctuations, poses a significant problem both in microbiology and in other fields, including cancer biology and immunology, where selection occurs within phenotypically heterogeneous populations of cells. Using “individual histories”—temporal sequences of all reproduction events and phenotypic changes of individuals and their ancestors—we present an alternative approach to quantifying selection in diverse experimental settings. Selection is viewed as a process that acts on histories, and a measure of selection that employs the distribution of histories is introduced. We apply this measure to phenotypically structured populations in fluctuating environments across different evolutionary regimes. Additionally, we show that reproduction events alone, recorded in the population’s tree of cell divisions, may be sufficient to accurately measure selection. The measure is thus applicable in a wide range of biological systems, from microorganisms—including species for which genetic tools do not yet exist—to cellular populations, such as tumors and stem cells, where detailed temporal data are becoming available.
Experimental demonstration of the importance of competition under disturbance
Authors: Violle Cyrille , Pu Zhichao , Jiang Lin
Published: July 2010

Ecologists have long recognized the roles of competition and disturbance in shaping ecological communities, and the combinatorial effects of these two factors have been the subject of substantial ecological research. Nevertheless, it is still unclear whether competition remains as an important structuring force in habitats strongly influenced by disturbance. The conventional belief remains that the importance of competition decreases with increasing disturbance, but limited theory suggests otherwise. Using protist communities established in laboratory microcosms, we demonstrate that disturbance does not diminish the importance of competition. Interspecific competition significantly increased rates of species extinction over a broad disturbance gradient, and increasing disturbance intensities increased, rather than decreased, the tempo of competitive exclusion. This community-level pattern is linked to the species-level pattern that interspecific competition led to most frequent extinctions of each species at the highest level of disturbance that the species can tolerate. Consequently, despite a strong tradeoff between competitive ability and disturbance tolerance across the competing species, species diversity generally declined with disturbance. The consistent structuring role of competition throughout the disturbance gradient underscores the need to understand competitive interactions and their consequences even in highly disturbed habitats.
Design of a potent CD1d-binding NKT cell ligand as a vaccine adjuvant
Authors: Li Xiangming , Fujio Masakazu , Imamura Masakazu , Wu Douglass , Vasan Sandhya , Wong Chi-Huey , Ho David D. , Tsuji Moriya
Published: July 2010

The glycolipid α-galactosylceramide (α-GalCer) has been shown to bind CD1d molecules to activate invariant natural killer T (iNKT) cells, and subsequently induce activation of various immune-competent cells, including dendritic cells, thereby providing a significant adjuvant effect for various vaccines. However, in phase I clinical trials, α-GalCer was shown to display only marginal biological activity. In our search for a glycolipid that can exert more potent stimulatory activity againstiNKT cells and dendritic cells and produce an adjuvant effect superior to α-GalCer, we performed step-wise screening assays on a focused library of 25 α-GalCer analogues. Assays included quantification of the magnitude of stimulatory activity against humaniNKT cells in vitro, binding affinity to human and murine CD1d molecules, and binding affinity to the invariant t cell receptor of humaniNKT cells. Through this rigorous and iterative screening process, we have identified a lead candidate glycolipid, 7DW8-5, that exhibits a superior adjuvant effect than α-GalCer on HIV and malaria vaccines in mice.
Knowing your users: the value of article database usage analysis
Authors: WAN Gang (Gary) , LIU Zao
Published: July 2010

This study analyzes the usage data of a major engineering article database, IEEE Xplore, from 2005 to 2008, at Texas A&M University. Usage data collected from the IEEE Xplore statistics website demonstrated some interesting patterns of user behavior. Usage of the database increased steadily from 2005 to 2007, but dropped in 2008 due to the launch of the library's new website; off‐campus usage was high in the first two years, but plunged in 2007 and 2008. Users from the Department of Electrical and Computer Engineering, and, to a lesser degree, from the Computer Science Department, were identified as major users of the database by IP statistics. The most heavily used journals and articles indicated that solid‐state circuits, microwave, information theory, and power systems were probably among core research areas in electrical and computer engineering for the university. The impact of conference articles in this database increased continuously throughout these years.
Article 50 million: an estimate of the number of scholarly articles in existence
Authors: JINHA Arif E.
Published: July 2010

How many scholarly research articles are there in existence? Journal articles first appeared in 1665, and the cumulative total is estimated here to have passed 50 million in 2009. This sum was arrived at based on published figures for global annual output for 2006, and analyses of annual output and growth rates published in the last decade.
Book Reviews
Authors: MLAMBO‐THATA Buhle
Published: July 2010

Evaluating Electronic Resource Programmes and Provision: Case Studies from Africa and Asia Diana Rosenberg (ed.) Oxford, International Network for the Availability of Scientific Publications, 2008, 124 pp. ISBN 978‐1802928‐31‐9, £10.00, pbk