bluuebunny/crossref_metadata_2025 huggingface dataset:
Time and frequency of applications of entomopathogenic nematodes and their persistence for control of western flower thrips Frankliniella occidentalis
Authors: Belay Difabachew , Ebssa Lemma , Borgemeister Christian
Published: October 2005

Post application persistence of two entomopathogenic nematode (EPN) species, Heterorhabditis bacteriophora strain HK3 and Steinernema carpocapsae strain DD136, was studied against soil-dwelling late second instar larvae (L2) of western flower thrips (WFT) Frankliniella occidentalis (Thysanoptera: Thripidae). The nematodes were applied at 200 and 400 infective juveniles (IJ) cm−2, and L2 WFT were introduced at 0 (same day), 3, 6, 9 or 12 days after nematode application (DANA). Heterorhabditis bacteriophora caused higher thrips mortality than S. carpocapsae in most of the tests and both species persisted for at least 6 days, causing WFT mortality of up to 76 and 37.8%, respectively. In a separate experiment, H. bacteriophora and S. feltiae (Filipjev) Sylt were applied at 200 and 400 IJ cm−2 once (10, 15, or 20 days) or twice (10 and 15, 10 and 20, or 15 and 20 days) after introduction of ten female and two male WFT adults onto bean plants (Phaseolus vulgaris). An early repeated application (10 and 15 days after adult WFT release) of H. bacteriophora at 200 IJ cm−2 resulted in significantly lower numbers WFT than a single applications at 400 IJ cm−2 indicating that better WFT control can be achieved if the same concentration is split over time. However, an early application (10 days after adult WFT release) of H. bacteriophora at 400 IJ cm−2 controlled WFT better than late applications, indicating that time of EPN application is additionally very crucial in WFT control. For S. feltiae, higher WFT mortality was recorded when nematodes were repeatedly applied on days 10 and 15 than in any other applications at a given concentration. Thus, an early application of an efficient and relatively more persistent nematode species, e.g., H. bacteriophora HK3, at a lower concentration but in a repeated manner, can result in higher thrips control than a single application at the higher concentration.
Impact of Aerosol Intrusions on Arctic Boundary Layer Clouds. Part I: 4 May 1998 Case
Authors: Carrió G. G. , Jiang H. , Cotton W. R.
Published: October 2005

The objective of this paper is to assess the impact of the entrainment of aerosol from above the inversion on the microphysical structure and radiative properties of boundary layer clouds. For that purpose, the Los Alamos National Laboratory sea ice model was implemented into the research and real-time versions of the Regional Atmospheric Modeling System at Colorado State University.

A series of cloud-resolving simulations have been performed for a mixed-phase Arctic boundary layer cloud using a new microphysical module that considers the explicit nucleation of cloud droplets. Different aerosol profiles based on observations were used for initialization. When more polluted initial ice-forming nuclei (IFN) profiles are assumed, the liquid water fraction of the cloud decreases while the total condensate path, the residence time of the ice particles, and the downwelling infrared radiation monotonically increase. Results suggest that increasing the aerosol concentrations above the boundary layer may increase sea ice melting rates when mixed-phase clouds are present.
Numerical Study of the 10 January 1998 Lake-Effect Bands Observed during Lake-ICE
Authors: Tripoli Gregory J.
Published: October 2005

This paper presents the results of a series of idealized cloud resolving simulations of the evolution of moist roll convection observed as part of the Lake-Induced Convection Experiment (Lake-ICE) that took place during the 1997/98 winter over central Lake Michigan. Satellite and radar observations of the roll convection depict striking linear rolls stretching from 10 km off the western shore of the lake, across to the eastern shore, and then continuing across Michigan. The spacing of the primary rolls was observed to be 6 km, giving a ratio of spacing to depth of about 5:1, which is consistent with theory. In addition, a longer wavelength (13 km) of stationary banding was observed parallel to the shoreline.

In an earlier study of this case, multiply nested simulations of the convective rolls based on real data variable initialization were successful in producing banded structures with similar spacing and location over the water to those observed using fine grid resolution of about 500 m. Unfortunately, the initial locations of simulated bands were organized primarily by numerical effects of grid interpolation. This suggested that the spacing of the bands was robust, but that their initial location was highly sensitive to subtle systematic forcings. In this paper, a set of idealized model experiments, designed to isolate the role that physically realistic local forcing plays in the organization of the rolls, was performed. Because externally generated upstream turbulence was suppressed in these tests so as not to bias the result, the generation of rolls was delayed until 20–30 km downwind of the observed location and the location simulated in the previous grid nesting experiments. It was shown that the subtle effects of the shoreline geometry were sufficient to spawn a near-surface streamwise vorticity that became the primary seed for roll development at the most efficient mode of roll convection. These results suggest that previous structures evolved in the upstream shear-driven land-based mixed layer were likely also important in determining where the nonlocal overturning was first triggered. It is not clear from these results whether the shear-driven structures that evolved over the land also played a significant role in organizing the structural geometry of the lake rolls. Results also suggested that the shore parallel bands were a robust feature of the atmospheric structure resulting from resonant gravity wave trapping in the frontal layer.
The Dynamics of Orographic Wake Formation in Flows with Upstream Blocking
Authors: Epifanio C. C. , Rotunno R.
Published: October 2005

The development of orographic wakes and vortices is revisited from the dynamical perspective of a three-dimensional (3D) vorticity-vector potential formulation. Particular emphasis is given to the role of upstream blocking in the formation of the wake.

Scaling arguments are first presented to explore the limiting form of the 3D vorticity inversion for the case of flow at small dynamical aspect ratio δ. It is shown that in the limit of small δ the inversion is determined completely by the two horizontal vorticity components—that is, the part of the velocity induced by the vertical component of vorticity vanishes in the small-δ limit. This result leads to an approximate formulation of small-δ fluid mechanics in which the three governing prognostic variables are the two horizontal vorticity components and the potential temperature. The remainder of the study then revisits the problem of orographic wake formation from the perspective of this small-δ vorticity dynamics framework.

Previous studies have suggested that one of the potential routes to stratified wake formation is through the blocking of flow on the upstream side of the barrier. This apparent link between blocking and wake formation is shown to be relatively straightforward in the small-δ vorticity context. In particular, it is shown that blocking of the flow inevitably leads to a horizontal vorticity distribution that favors deceleration of the leeside flow at the ground. This process of leeside flow deceleration, as well as the subsequent time evolution of the wake, is illustrated through a series of numerical initial-value problems involving flows past 2D and 3D barriers. It is proposed that the initiation of the wake flow in these stratified problems resembles the flow produced by a retracting piston in shallow-water theory.
Large-Amplitude Mountain Wave Breaking over Greenland
Authors: Doyle James D. , Shapiro Melvyn A. , Jiang Qingfang , Bartels Diana L.
Published: October 2005

A large-amplitude mountain wave generated by strong southwesterly flow over southern Greenland was observed during the Fronts and Atlantic Storm-Track Experiment (FASTEX) on 29 January 1997 by the NOAA G-IV research aircraft. Dropwindsondes deployed every 50 km and flight level data depict a vertically propagating large-amplitude wave with deep convectively unstable layers, potential temperature perturbations of 25 K that deformed the tropopause and lower stratosphere, and a vertical velocity maximum of nearly 10 m s−1 in the stratosphere. The wave breaking was associated with a large vertical flux of horizontal momentum and dominated by quasi-isotropic turbulence. The Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) nonhydrostatic model with four-nested grid meshes with a minimum resolution of 1.7 km accurately simulates the amplitude, location, and timing of the mountain wave and turbulent breakdown. Finescale low-velocity plumes that resemble wakelike structures emanate from highly dissipative turbulent regions of wave breaking in the lower stratosphere. Idealized adiabatic three-dimensional simulations suggest that steep terrain slopes increase the effective Rossby number of the relatively wide Greenland plateau, decrease the sensitivity of the wave characteristics to rotation, and ultimately increase the tendency for wave breaking. Linear theory and idealized simulations indicate that diabatic cooling within the boundary layer above the Greenland ice sheet augments the effective mountain height and increases the wave amplitude and potential for wave breaking for relatively wide obstacles such as Greenland.
Drizzle in Stratiform Boundary Layer Clouds. Part I: Vertical and Horizontal Structure
Authors: Wood R.
Published: October 2005

Detailed observations of stratiform boundary layer clouds on 12 days are examined with specific reference to drizzle formation processes. The clouds differ considerably in mean thickness, liquid water path (LWP), and droplet concentration. Cloud-base precipitation rates differ by a factor of 20 between cases. The lowest precipitation rate is found in the case with the highest droplet concentration even though this case had by far the highest LWP, suggesting that drizzle can be severely suppressed in polluted clouds.

The vertical and horizontal structure of cloud and drizzle liquid water and bulk microphysical parameters are examined in detail. In general, the highest concentration of r > 20 μm drizzle drops is found toward the top of the cloud, and the mean volume radius of the drizzle drops increases monotonically from cloud top to base. The resulting precipitation rates are largest at the cloud base but decrease markedly only in the upper third of the cloud. Below cloud, precipitation rates decrease markedly with distance below base due to evaporation, and are broadly consistent in most cases with the results from a simple sedimentation–evaporation model. Evidence is presented that suggests evaporating drizzle is cooling regions of the subcloud layer, which could result in dynamical feedbacks. A composite power spectrum of the horizontal spatial series of precipitation rate is found to exhibit a power-law scaling from the smallest observable scales to close to the maximum observable scale (∼30 km). The exponent is considerably lower (1.1–1.2) than corresponding exponents for LWP variability obtained in other studies (∼1.5–2), demonstrating that there is relatively more variability of drizzle on small scales. Singular measures analysis shows that drizzle fields are much more intermittent than the cloud liquid water content fields, consistent with a drizzle production process that depends strongly upon liquid water content. The adiabaticity of the clouds, which can be modeled as a simple balance between drizzle loss and turbulent replenishment, is found to decrease if the time scale for drizzle loss is shorter than roughly 5–10 eddy turnover time scales. Finally, the data are compared with three simple scalings derived from recent observations of drizzle in subtropical stratocumulus clouds.
A Multimoment Bulk Microphysics Parameterization. Part II: A Proposed Three-Moment Closure and Scheme Description
Authors: Milbrandt J. A. , Yau M. K.
Published: October 2005

Many two-moment bulk schemes use a three-parameter gamma distribution of the form N(D) = N0Dαe−λD to describe the size spectrum of a given hydrometeor category. These schemes predict changes to the mass content and the total number concentration thereby allowing N0 and λ to vary as prognostic parameters while fixing the shape parameter, α. As was shown in Part I of this study, the shape parameter, which represents the relative dispersion of the hydrometeor size spectrum, plays an important role in the computation of sedimentation and instantaneous growth rates in bulk microphysics schemes. Significant improvement was shown by allowing α to vary as a diagnostic function of the predicted moments rather than using a fixed-value approach. Ideally, however, α should be an independent prognostic parameter.

In this paper, a closure formulation is developed for calculating the source and sink terms of a third moment of the size distribution—the radar reflectivity. With predictive equations for the mass content, total number concentration, and radar reflectivity, α becomes a fully prognostic variable and a three-moment parameterization becomes feasible. A new bulk microphysics scheme is presented and described. The full version of the scheme predicts three moments for all precipitating hydrometeor categories.

Simulations of an idealized hailstorm in the context of a 1D kinematic cloud model employing the one-moment, two-moment, and three-moment versions of the scheme are compared. The vertical distribution of the hydrometeor mass contents using the two-moment version with diagnostic-α relations are much closer to the three-moment than the one-moment simulation. However, the evolution of the surface precipitation rate is notably different between the three-moment and two-moment schemes.
The Continuum and Dynamics of Northern Hemisphere Teleconnection Patterns
Authors: Franzke Christian , Feldstein Steven B.
Published: October 2005

This study presents an alternative interpretation for Northern Hemisphere teleconnection patterns. Rather than comprising several different recurrent regimes, this study suggests that there is a continuum of teleconnection patterns. This interpretation indicates either that 1) all members of the continuum can be expressed in terms of a linear combination of a small number of real physical modes that correspond to basis functions or 2) that most low-frequency patterns within the continuum are real physical patterns, each having its own spatial structure and frequency of occurrence.

Daily NCEP–NCAR reanalysis data are used that cover the boreal winters of 1958–97. A set of nonorthogonal basis functions that span the continuum is derived. The leading basis functions correspond to well-known patterns such as the Pacific–North American teleconnection and North Atlantic Oscillation. Evidence for the continuum perspective is based on the finding that 1) most members of the continuum tend to have similar variance and autocorrelation time scales and 2) that members of the continuum show dynamical characteristics that are intermediate between those of the surrounding basis functions. The latter finding is obtained by examining the streamfunction tendency equation both for the basis functions and some members of the continuum.

The streamfunction tendency equation analysis suggests that North Pacific patterns (basis functions and continuum) are primarily driven by their interaction with the climatological stationary eddies and that North Atlantic patterns are primarily driven by transient eddy vorticity fluxes. The decay mechanism for all patterns is similar, being due to the impact of low-frequency (period greater than 10 days) transient eddies and horizontal divergence. Analysis with outgoing longwave radiation shows that tropical convection is found to play a much greater role in exciting North Pacific patterns. A plausible explanation for these differences between the North Atlantic and North Pacific patterns is presented.
Net Exchange Reformulation of Radiative Transfer in the CO2 15-μm Band on Mars
Authors: Dufresne Jean-Louis , Fournier Richard , Hourdin Christophe , Hourdin Frédéric
Published: October 2005

The net exchange formulation (NEF) is an alternative to the usual radiative transfer formulation. It was proposed by two authors in 1967, but until now, this formulation has been used only in a very few cases for atmospheric studies. The aim of this paper is to present the NEF and its main advantages and to illustrate them in the case of planet Mars.

In the NEF, the radiative fluxes are no longer considered. The basic variables are the net exchange rates between each pair of atmospheric layers i, j. NEF offers a meaningful matrix representation of radiative exchanges, allows qualification of the dominant contributions to the local heating rates, and provides a general framework to develop approximations satisfying reciprocity of radiative transfer as well as the first and second principles of thermodynamics. This may be very useful to develop fast radiative codes for GCMs.

A radiative code developed along those lines is presented for a GCM of Mars. It is shown that computing the most important optical exchange factors at each time step and the other exchange factors only a few times a day strongly reduces the computation time without any significant precision lost. With this solution, the computation time increases proportionally to the number N of the vertical layers and no longer proportionally to its square N 2. Some specific points, such as numerical instabilities that may appear in the high atmosphere and errors that may be introduced if inappropriate treatments are performed when reflection at the surface occurs, are also investigated.
Observations of Entrainment in Eastern Pacific Marine Stratocumulus Using Three Conserved Scalars
Authors: Faloona Ian , Lenschow Donald H. , Campos Teresa , Stevens B. , van Zanten M. , Blomquist B. , Thornton D. , Bandy Alan , Gerber Hermann
Published: October 2005

Fast measurements of three scalars, ozone, dimethyl sulfide (DMS), and total water, are used to investigate the entrainment process in the stratocumulus-topped boundary layer (STBL) observed over the eastern subtropical Pacific during the second Dynamics and Chemistry of Marine Stratocumulus Experiment (DYCOMS-II). Direct measurement of the flux profiles by eddy covariance is used to estimate the entrainment velocity, the average rate at which the boundary layer grows diabatically via incorporation of overlying free tropospheric air. The entrainment velocities observed over the course of the mission, which took place during July 2001, ranged from 0.12 to 0.72 cm s−1, and appear to outpace the estimated large-scale subsidence as the boundary layer advects over warmer sea surface temperatures. Observed entrainment velocities display only a weak correlation with the buoyancy Richardson number defined at the inversion, which suggests that processes other than inversion strength, such as wind shear, might play a larger role in driving entrainment in the STBL than previously recognized.

This study is the first to use DMS as an entrainment tracer because the high-rate mass spectrometric technique has only recently been developed. The biogenic sulfur compound shows great promise for such investigations in marine environments because the free tropospheric concentrations are virtually nonexistent, and it therefore serves as an unambiguous marker of boundary layer air. As such, individual mixing events can be analyzed to determine the mixing fraction of boundary layer and free tropospheric air, and in several such cases buoyancy reversal was observed despite the absence of large-scale dissipation of the cloud field as postulated by cloud-top entrainment instability. Moreover, the redundancy attained in using three separate scalars allows for an investigation of the average height scales above the inversion from where air is blended into the STBL, and this tends to be less than 80 m above the mean inversion height, implying that the entrainment process occurs on very small scales.
Mountain-Wave Momentum Flux in an Evolving Synoptic-Scale Flow
Authors: Chen Chih-Chieh , Durran Dale R. , Hakim Gregory J.
Published: October 2005

The evolution of mountain-wave-induced momentum flux is examined through idealized numerical simulations during the passage of a time-evolving synoptic-scale flow over an isolated 3D mountain of height h. The dynamically consistent synoptic-scale flow U accelerates and decelerates with a period of 50 h; the maximum wind arrives over the mountain at 25 h. The synoptic-scale static stability N is constant, so the time dependence of the nonlinearity parameter, ɛ(t) = Nh/U(t), is symmetric about a minimum value at 25 h.

The evolution of the vertical profile of momentum flux shows substantial asymmetry about the midpoint of the cycle even though the nonlinearity parameter is symmetric. Larger downward momentum fluxes are found during the accelerating phase, and the largest momentum fluxes occur in the mid- and upper troposphere before the maximum background flow arrives at the mountain. For a period of roughly 15 h, this vertical distribution of momentum flux accelerates the lower-tropospheric zonal-mean winds due to low-level momentum flux convergence.

Conservation of wave action and Wentzel–Kramers–Brillouin (WKB) ray tracing are used to reconstruct the time–altitude dependence of the mountain-wave momentum flux in a semianalytic procedure that is completely independent of the full numerical simulations. For quasi-linear cases, the reconstructions show good agreement with the numerical simulations, implying that the basic asymmetry obtained in the full numerical simulations may be interpreted using WKB theory. These results demonstrate that even slow variations in the mean flow, with a time scale of 2 days, play a dominant role in regulating the vertical profile of mountain-wave-induced momentum flux.

The time evolution of cross-mountain pressure drag is also examined in this study. For almost-linear cases, the pressure drag is well predicted under steady-state linear theory by using the instantaneous incident flow. Nevertheless, for mountains high enough to preserve a moderate degree of nonlinearity when the synoptic-scale incident flow is strongest, the evolution of cross-mountain pressure drag is no longer symmetric about the time of maximum wind. A higher drag state is found when the cross-mountain flow is accelerating. These results suggest that the local character of the topographically induced disturbance cannot be solely determined by the instantaneous value of the nonlinearity parameter ɛ.
An Autonomous Doppler Sodar Wind Profiling System
Authors: Anderson Philip S. , Ladkin Russell S. , Renfrew Ian A.
Published: October 2005

An autonomous Doppler sodar wind profiling system has been designed, built, tested, and then deployed for 2 years at a remote site in Coats Land, Antarctica. The system is designed around a commercially available phased-array sodar (a Scintec flat-array sodar, FAS64) and powered from five modular power system units. Each power unit comprises two batteries, two photovoltaic solar panels, and two vertical axis wind generators, plus charging control and isolation circuitry. The sodar’s main processing unit is located at the antenna, but is controlled from a manned research station 50 km distant, in real time, by a line-of-sight UHF radio link. Data from an integral automatic weather station (AWS) are also transmitted over the radio link, allowing meteorologically informed decisions on whether or not to operate the Doppler sodar. Over the 2-yr experiment dozens of sounding episodes, lasting from a few hours to a few days, were obtained. Successful soundings were obtained in temperatures down to −33°C, and wind speeds up to 12 m s−1. In general, the wind data quality was good, but the range was disappointing, probably as a result of the strongly stable atmospheric conditions that were experienced. The wind profiling system that is described has been used to obtain the first remote wintertime observations of katabatic winds over the Antarctic continent.
Statistical Characterization of Zonal and Meridional Ocean Wind Stress
Authors: Gille Sarah T.
Published: October 2005

Four years of ocean vector wind data are used to evaluate statistics of wind stress over the ocean. Raw swath wind stresses derived from the Quick Scatterometer (QuikSCAT) are compared with five different global gridded wind products, including products based on scatterometer observations, meteorological analysis winds from the European Centre for Medium-Range Weather Forecasts, and reanalysis winds from the National Centers for Environmental Prediction. Buoy winds from a limited number of sites in the Pacific Ocean are also considered.

Probability density functions (PDFs) computed for latitudinal bands show that mean wind stresses for the six global products are largely in agreement, while variances differ substantially, by a factor of 2 or more, with swath wind stresses indicating highest variances for meridional winds and for zonal winds outside the Tropics. Higher moments of the PDFs also differ. Kurtoses are large for all wind products, implying that PDFs are not Gaussian. None of the available gridded products fully captures the range of extreme wind events seen in the raw swath data.

Frequency spectra for the five gridded products agree with frequency spectra from swath data at low frequencies, but spectral slopes differ at higher frequencies, particularly for frequencies greater than 100 cycles per year (cpy), which are poorly resolved by a single scatterometer. In the frequency range between 10 and 90 cpy that is resolved by the scatterometer, spectra derived from swath data are flatter than spectra from gridded products and are judged to be flatter than ω−2/3 at all latitudes.
Absolute Calibration of Jason-1 and Envisat Altimeter Ku-Band Radar Cross Sections from Cross Comparison with TRMM Precipitation Radar Measurements
Authors: Tran N. , Zanife O-Z. , Chapron B. , Vandemark D. , Vincent P.
Published: October 2005

One year of collocated, rain-free nadir Ku-band backscatter cross-section measurements from the Tropical Rainfall Mapping Mission (TRMM) precipitation radar (PR) and both Jason-1 and Envisat RA-2 altimeter measurements have been compiled to compare these three sources of Ku-band radar cross section. With the exception of a +1.46 dB relative offset between Jason-1 and PR measurements and a −1.40 dB offset between Envisat and PR ones, all three Ku-band measurements compare very well in terms of dependencies upon model wind speed estimates and significant wave height measurements. The altimeter radars and the rain radar thus provide consistent measurements, and observed biases can be rationalized as differences in the radar calibration. The precipitation radar, which also covers off-nadir measurements, has been absolutely calibrated using an active radar calibrator. Consequently, the observed relative offsets can be used to indirectly calibrate both Jason-1 and Envisat altimeter Ku-band radar cross sections in an absolute sense.
Remote Measurements of Horizontal Eddy Diffusivity
Authors: Bogucki Darek J. , Jones Burton H. , Carr Mary-Elena
Published: October 2005

The rate of horizontal diffusivity or lateral dispersion is key to understanding the dispersion of tracers and contaminants in the ocean, and it is an elusive, yet crucial, parameter in numerical models of circulation. However, the difficulty of parameterizing horizontal mixing is exacerbated in the shallow coastal ocean, which points to the need for more direct measurements. Here, a novel and inexpensive approach to remotely measure the rate of horizontal diffusivity is proposed. Current shipboard measurement techniques require repeated surveys and are thus time consuming and labor intensive. Furthermore, intensive in situ sampling is generally impractical for routine coastal management or for rapid assessment in the case of emergencies. A remote approach is particularly useful in shallow coastal regions or those with complex bathymetry.

A time series of images from a dye-release experiment was obtained with a standard three-megapixel digital camera from a helicopter that hovered over the study area. The red–green–blue (RGB) images were then 1) analyzed to distinguish the dye from the ambient color of the water and adjacent land features, 2) orthorectified, and 3) analyzed to obtain advection and diffusion rates of the thin subsurface dye layer. A horizontal current of the order of 6 cm s−1 was found. The estimated horizontal eddy diffusivity rate for scales of O(10 m) in the harbor was 0.1 m2 s−1. The dye diffusivity and advection rate that are calculated from the images are consistent with independent calculations based on in situ measurements of current speed fluctuations.
Impact of Information on Customer Fairness Perceptions of Hotel Revenue Management
Authors: Choi Sunmee , Mattila Anna S.
Published: October 2005

Despite the prospective benefits of a revenue management (RM) program, some hotel managers remain concerned that customers perceive RM as being unfair. Studies have shown that offering customers information on a hotel’s pricing practices can enhance their perceptions of fairness. To determine how much and what type of information hotels should provide in this context, researchers administered a scenario-based survey to 120 travelers. The study found that giving would-be guests relatively complete information about how a hotel’s RM policies operate increases their perception of RM’s fairness. The study found that merely letting travelers know that the hotel’s rates vary was not enough to improve customers’ perceptions of fairness (even with a favorable rate). When respondents were also told that rates varied according to day of the week (with weekend rates being lower), length of stay, and how far in advance the reservation was made, their perceptions of fairness improved significantly.
To Walk or Not to Walk? The Hierarchy of Walking Needs
Authors: Alfonzo Mariela A.
Published: October 2005

The multitude of quality of life problems associated with declining walking rates has impelled researchers from various disciplines to identify factors related to this behavior change. Currently, this body of research is in need of a transdisciplinary, multilevel theoretical model that can help explain howindividual, group, regional, and physical-environmental factors all affect physical activity behaviors. To address this gap, this article offers a social-ecological model of walking that presents a dynamic, causal model of the decision-making process. Within the model, a hierarchy of walking needs operates and organizes five levels of needs hierarchically and presents them as antecedents within the walking decision-making process. This model can (a) serve as a framework by which to understand the relative significance of the cornucopia of variables identified by existing research, (b) offer hypotheses for how these factors affect peoples' decision to walk, and (c) help to guide future research and practice.
The Effect of Mood on Detection of Covariation
Authors: Braverman Julia
Published: October 2005

The purpose of this research is to explore the effect of mood on the detection of covariation. Predictions were based on an assumption that sad moods facilitate a data-driven information elaboration style and careful data scrutinizing, whereas happy moods predispose individuals toward top-down information processing and decrease the attention given to cognitive tasks. The primary dependent variable involved is the detection of covariation between facial features and personal information and the use of this information for evaluating new target faces. The findings support the view that sad mood facilitates both conscious and unconscious detection of covariation because it increases motivation to engage in the task. Limiting available cognitive resources does not eliminate the effect of mood on the detecting of covariation.
Sport Spectators and the Social Consequences of Commodification
Authors: Giulianotti Richard
Published: October 2005

The commodification of football has been the subject of substantial sociological debate but has received relatively limited scrutiny in terms of sustained comparative empirical research. This article draws heavily on interviews with supporter groups, journalists, and officials in Scottish football to examine a range of issues relating to fan experiences and understandings of football's commodification. The author examines how fans respond to their labeling as customers and considers whether they are alienated or marginalized from football in economic and cultural terms. The author explores how the game's commodification can be at the expense of themost deserving supporters and undermines the future reproduction of fan communities. The author concludes by arguing for a nuanced sociological reading of supporters in regard to commodification, which appreciates both the fans' market pragmatism and their normative critiques of distributive justice in the game.
The Effect of Direction and Reaction on the Neuromuscular and Biomechanical Characteristics of the Knee during Tasks that Simulate the Noncontact Anterior Cruciate Ligament Injury Mechanism
Authors: Sell Timothy C. , Ferris Cheryl M. , Abt John P. , Tsai Yung-Shen , Myers Joseph B. , Fu Freddie H. , Lephart Scott M.
Published: October 2005

Background

Jumping and landing tasks that have a change in direction have been implicated as a mechanism of noncontact anterior cruciate ligament injury. Yet, to date, neuromuscular and biomechanical research has focused primarily on straight landing tasks during planned jumps.

Hypothesis

Lateral and reactive jumps increase the neuromuscular and biomechanical demands placed on the anterior cruciate ligament, and women perform these tasks differently from men.

Study Design

Controlled laboratory study.

Methods

A total of 18 male and 17 female healthy high school basketball players underwent an analysis of the knee during planned and reactive 2-legged stop-jump tasks in 3 different directions that included novel methodology to incorporate a reactive component. Ground-reaction forces, joint kinematics, joint kinetics, and electromyographic activity were assessed during the tasks.

Results

Jump direction and task (planned or reactive) significantly affected joint angles, ground-reaction forces, knee joint moments, and proximal anterior tibia shear forces; female players demonstrated different kinematic, kinetic, and electromyographic characteristics during these tasks.

Conclusion and Clinical Relevance

Jump direction significantly influenced knee biomechanics, suggesting that lateral jumps are the most dangerous of the stop-jumps. Reactive jumps were also significantly different, suggesting differences between planned laboratory experiments and actual athletic competition. The results of this study indicate that directional and reactive jumps should be included in research methodology and injury-prevention programs.
Hamstring Muscle Function after Tendon Harvest for Anterior Cruciate Ligament Reconstruction
Authors: Takeda Yoshitsugu , Kashiwaguchi Shinji , Matsuura Tetsuya , Higashida Takeshi , Minato Akira
Published: October 2005

Background

Regeneration of the semitendinosus and gracilis tendons after harvesting for anterior cruciate ligament reconstruction has been reported; however, muscle belly function after tendon regeneration has not been well documented.

Hypothesis

The semitendinosus and gracilis muscles are highly activated during knee flexion if their tendons are well regenerated after anterior cruciate ligament reconstruction.

Study Design

Descriptive laboratory study.

Methods

Hamstring muscle activation in 11 patients who had undergone anterior cruciate ligament reconstruction with semitendinosus and gracilis tendons was evaluated by measuring the increase of T2 relaxation time measured via magnetic resonance imaging after knee flexion exercise. Tendon regeneration was evaluated via magnetic resonance imaging.

Results

Both muscles increased T2 relaxation time after knee flexion exercise in the operated legs, and there was no significant difference in those values between the operated and nonoperated legs. All the semitendinosus tendons were regenerated at or below the joint line, but no gracilis tendons were observed beyond the joint line. The results indicated that both muscles were highly recruited during knee flexion, regardless of the degree of their tendon regeneration.

Conclusion

The semitendinosus and gracilis muscles are able to restore or maintain their contractile capability after harvest of their tendons for anterior cruciate ligament reconstruction, regardless of the degree of regeneration.
Indomethacin and Celecoxib Impair Rotator Cuff Tendon-to-Bone Healing
Authors: Cohen David B. , Kawamura Sumito , Ehteshami John R. , Rodeo Scott A.
Published: October 2005

Background

Nonsteroidal anti-inflammatory drugs are commonly prescribed after rotator cuff repair. These agents can impair bone formation, but no studies have evaluated their impact on tendon-to-bone healing.

Hypothesis

Traditional nonselective nonsteroidal anti-inflammatory drugs and cyclooxygenase-2–specific nonsteroidal antiinflammatory drugs interfere with tendon-to-bone healing.

Study Design

Controlled laboratory study.

Methods

One hundred eighty Sprague-Dawley rats underwent acute rotator cuff repairs. Postoperatively, 60 rats received 14 days of celecoxib, a cyclooxygenase-2–specific nonsteroidal anti-inflammatory drug; 60 received indomethacin, a traditional nonselective nonsteroidal anti-inflammatory drug; and 60 received standard rat chow. Animals were sacrificed at 2, 4, and 8 weeks and evaluated by gross inspection, biomechanical testing, histologic analysis, and polarized light microscopy to quantify collagen formation and maturation.

Results

Five tendons completely failed to heal (4 celecoxib, 1 indomethacin). There were significantly lower failure loads in the celecoxib and indomethacin groups compared with the control groups at 2, 4, and 8 weeks (P< .001), with no significant difference between nonsteroidal anti-inflammatory drug groups. There were significant differences in collagen organization and maturation between the controls and both nonsteroidal anti-inflammatory drug groups at 4 and 8 weeks (P< .001). Controls demonstrated progressively increasing collagen organization during the course of the study (P< .001), whereas the nonsteroidal anti-inflammatory drug groups did not.

Conclusion

Traditional and cyclooxygenase-2–specific nonsteroidal anti-inflammatory drugs significantly inhibited tendon-tobone healing. This inhibition appears linked to cyclooxygenase-2.

Clinical Relevance

If the results of this study are verified in a larger animal model, the common practice of administering nonsteroidal anti-inflammatory drugs after rotator cuff repair should be reconsidered.
Critical Reflection on Cultural Difference in the Computer Conference
Authors: Ziegahn Linda
Published: October 2005

Adult educators have a strong interest in designing courses that stimulate learning toward critical, more inclusive cultural perspectives. Critical reflection is a key component of both intercultural learning and a growing medium of instruction, the asynchronous computer conference (CC). This study combined qualitative methodology with a framework for assessment of intercultural reflection to examine interactions between intercultural experience and issues and cognitive and affective approaches to reflection in a graduate course exploring cultural difference taught through the CC medium. Results revealed that beliefs about cultural difference were mediated through critical self-reflection approaches through which students linked cultural positions to inequity, embraced negative emotions, questioned prejudices, reframed underlying premises, and linked experiences to previously learned habits. Online discussion was strongly influenced by the topics of race and, secondarily, by experience as marginalized biculturals or international sojourners.
The Political Spectacle of Arizona's Proposition 203
Authors: Wright Wayne E.
Published: October 2005

Arizona's Proposition 203 places restrictions on bilingual and English-as-asecond-language programs and essentiality mandates English-only education for English language learners (ELLs). This article provides an analysis of this initiative and the wide variations in its interpretation and implementation. Data sources include official policy and related documents, media coverage, and observations of key policy events. The findings provide evidence that Proposition 203 and its implementation are political spectacle, rather than democratic rationale policy making with true concern for ELL students. The analysis focuses on the components of the political spectacle framework evident in the initiative, its campaign(s), and its implementation, including the use of symbolic language, the use of plots and story lines, the creation of leaders (heroes) and enemies, the evoking of symbols of rationality, and distinctions between on-stage and off-stage actions. The article concludes with a discussion of the implications for English language learners in Arizona.
Drug-Related Visits to the Emergency Department
Authors: Zed Peter J.
Published: October 2005

Over the past few years, several published reports have addressed the problem of drug-related morbidity in various practice settings. Studies evaluating drug-related hospitalization have estimated that approximately 5% to 10% of all hospital admissions are drug related. Unfortunately, many of these studies have excluded patients seeking medical attention in the emergency department (ED) but not requiring hospital admission. Drug-related visits to the emergency department are a significant problem and contribute to overall pressures on our current health care system. Despite the limited information published regarding drug-related ED visits, several studies describe the impact of this issue. The purpose of this article is to review the current literature pertaining to the incidence, classification, severity, preventability, and economic impact of drug-related visits to the emergency department.
Social Activism and Disability Rates in American Indian Tribes
Authors: Young Frank W.
Published: October 2005

This study tests the hypothesis that the social activism that some American Indian tribes engaged in during the 1960s to 1990s improved their average health, as measured by 1990 rates of mobility and work disability. The hypothesis is tested on a subuniverse of 59 reservation units using conventional regression techniques, including a factor analysis that generated three factors: Socioeconomic status (SES), Claims Against the Government, and Cultural Renewal. SES predicted lower rates of both types of disability across the sample. The activism predictions were supported mainly in the Southwest region where Claims and Renewal predicted lower levels of physical limitations. In the non-Southwest tribes, only Claims predicted (weakly) fewer claims for work disability. Alternative hypotheses are discussed.
Thrombospondin-1 controls vascular platelet recruitment and thrombus adherence in mice by protecting (sub)endothelial VWF from cleavage by ADAMTS13
Authors: Bonnefoy Arnaud , Daenens Kim , Feys Hendrik B. , De Vos Rita , Vandervoort Petra , Vermylen Jos , Lawler Jack , Hoylaerts Marc F.
Published: October 2005

The function of thrombospondin-1 (TSP-1) in hemostasis was investigated in wild-type (WT) and Tsp1-/- mice, via dynamic platelet interaction studies with A23187-stimulated mesenteric endothelium and with photochemically injured cecum subendothelium. Injected calcein-labeled WT platelets tethered or firmly adhered to almost all A23187-stimulated blood vessels of WT mice, but Tsp1-/- platelets tethered to 45% and adhered to 25.8% of stimulated Tsp1-/- vessels only. Stimulation generated temporary endothelium-associated ultralarge von Willebrand factor (VWF) multimers, triggering platelet string formation in 48% of WT versus 20% of Tsp1-/- vessels. Injection of human TSP-1 or thrombotic thrombocytopenic purpura (TTP) patient-derived neutralizing anti-ADAMTS13 antibodies corrected the defective platelet recruitment in Tsp1-/- mice, while having a moderate effect in WT mice. Photochemical injury of intestinal blood vessels induced thrombotic occlusions with longer occlusion times in Tsp1-/- venules (1027 ± 377 seconds) and arterioles (858 ± 289 seconds) than in WT vessels (559 ± 241 seconds, P < .001; 443 ± 413 seconds, P < .003) due to defective thrombus adherence, resulting in embolization of complete thrombi, a defect restored by both human TSP-1 and anti-ADAMTS13 antibodies. We conclude that in a shear field, soluble or local platelet-released TSP-1 can protect unfolded endothelium-bound and subendothelial VWF from degradation by plasma ADAMTS13, thus securing platelet tethering and thrombus adherence to inflamed and injured endothelium, respectively.
Dendritic cells regulate T-cell deattachment through the integrin-interacting protein CYTIP
Authors: Hofer Susanne , Pfeil Karina , Niederegger Harald , Ebner Susanne , Nguyen Van Anh , Kremmer Elisabeth , Auffinger Margit , Neyer Susanne , Fürhapter Christina , Heufler Christine
Published: October 2005

When T cells are primed by dendritic cells (DCs) to initiate antigen-specific immune responses screening for matching antigen receptor-MHC/peptide pairs takes place in DC-T-cell conjugates. For an immune response DC-T-cell conjugates formed during priming events need to dissolve. Although detailed knowledge on molecules involved in the conjugate formation is available, dissolving of them has not been considered to be an active process. Here, we identify CYTIP (cytohesin-interacting protein) to mediate DC-T-cell deattachment. CYTIP, which is induced during maturation of DCs, shortly accumulates to the contact zones with T cells within the first hour of coculture. Specific silencing of CYTIP results in stronger adhesion of DCs to T cells and to fibronectin. When a need for deattachment is created in a T-cell priming assay by only partially loading DCs with antigen, CYTIP silencing causes reduced priming capacity. Thus, CYTIP allows DCs to actively control DC-T-cell interactions.
How I treat refractory CLL
Authors: Montserrat Emili , Moreno Carol , Esteve Jordi , Urbano-Ispizua Alvaro , Giné Eva , Bosch Francesc
Published: October 2005

Therapy for patients with chronic lymphocytic leukemia (CLL) has greatly changed over the past few years. After years of stagnation, with treatment revolving around the use of rather ineffective drugs such as alkylators, many patients are now being treated with more effective agents such as purine analogs either alone or combined with other drugs and/or monoclonal antibodies. Treatment of patients refractory to these treatments is particularly challenging and should be decided only upon a careful evaluation of the disease, patient characteristics, and prognostic factors. Refractory disease should be clearly separated from relapsing disease. The only curative therapy for patients with CLL, including those with refractory disease, is allogeneic stem cell transplantation. However, the use of allogeneic transplantation is limited because of the advanced age of most patients and the high transplant-related mortality (TRM). Transplants with nonmyeloablative regimens may reduce TRM and allow more patients to receive transplants more safely. For patients in whom an allogeneic transplantation is not feasible or in whom it is deemed inappropriate, participation in phase 2 trials should be encouraged. Finally, to investigate mechanisms to overcome resistance to therapy in CLL and to identify patients that might gain benefit from early, intensive therapies (eg, based on biologic markers) constitute a challenge that needs active investigation.