bluuebunny/crossref_metadata_2025 huggingface dataset:
Trends in Incidence, Risk Factors, and Survival in Symptomatic Lacunar Stroke in Dijon, France, From 1989 to 2006
Authors: Bejot Yannick , Catteau Aurélie , Caillier Marie , Rouaud Olivier , Durier Jerome , Marie Christine , Di Carlo Antonio , Osseby Guy-Victor , Moreau Thibault , Giroud Maurice
Published: April 2008

Background and Purpose—

Lacunar infarcts are usually regarded as benign stroke, but population-based studies are required to assess the exact place of this stroke subtype in cerebrovascular pathology.

Methods—

We evaluated trends in incidence rates, risk factor profiles, and survival rates in symptomatic lacunar stroke from a prospective population-based registry from 1989 to 2006.

Results—

We recorded 2536 ischemic strokes. Among these, 715 (28%) were lacunar infarcts (354 men and 361 women). From 1989 to 2006, we observed a significant rise in the incidence of lacunar stroke in the 2 sexes considered together (relative risk, 1.02; 95% CI, 1.005 to 1.035;
P
=0.007), whereas the variation was not significant in either men or women when considered separately. Incidence rates significantly increased in young patients under 65 years old (relative risk, 1.049; 95% CI, 1.0175 to 1.0817;
P
=0.002). Concerning the distribution of cerebrovascular risk factors, lacunar stroke differed from nonlacunar stroke only with regard to the lower prevalence of a history of atrial fibrillation in the former (
P
<0.001). For lacunar infarcts, survival rates were 96% at 1 month (95% CI, 0.94 to 0.97), 86% at 1 year (95% CI, 0.83 to 0.89), and 78% at 2 years (95% CI, 0.75 to 0.81) and were significantly higher than those for nonlacunar stroke (hazard ratio, 2.05; 95% CI, 1.70 to 2.47;
P
<0.001).

Conclusion—

Our results suggest a significant increase in the incidence rates of lacunar stroke with a relatively good short-term prognosis in terms of survival. The association among hypertension, diabetes mellitus, and lacunar stroke was no stronger than the association between these 2 risk factors and nonlacunar stroke.
Sparse Coding via Thresholding and Local Competition in Neural Circuits
Authors: Rozell Christopher J. , Johnson Don H. , Baraniuk Richard G. , Olshausen Bruno A.
Published: April 2008

While evidence indicates that neural systems may be employing sparse approximations to represent sensed stimuli, the mechanisms underlying this ability are not understood. We describe a locally competitive algorithm (LCA) that solves a collection of sparse coding principles minimizing a weighted combination of mean-squared error and a coefficient cost function. LCAs are designed to be implemented in a dynamical system composed of many neuron-like elements operating in parallel. These algorithms use thresholding functions to induce local (usually one-way) inhibitory competitions between nodes to produce sparse representations. LCAs produce coefficients with sparsity levels comparable to the most popular centralized sparse coding algorithms while being readily suited for neural implementation. Additionally, LCA coefficients for video sequences demonstrate inertial properties that are both qualitatively and quantitatively more regular (i.e., smoother and more predictable) than the coefficients produced by greedy algorithms.
Dependence of Neuronal Correlations on Filter Characteristics and Marginal Spike Train Statistics
Authors: Tetzlaff Tom , Rotter Stefan , Stark Eran , Abeles Moshe , Aertsen Ad , Diesmann Markus
Published: April 2008

Correlated neural activity has been observed at various signal levels (e.g., spike count, membrane potential, local field potential, EEG, fMRI BOLD). Most of these signals can be considered as superpositions of spike trains filtered by components of the neural system (synapses, membranes) and the measurement process. It is largely unknown how the spike train correlation structure is altered by this filtering and what the consequences for the dynamics of the system and for the interpretation of measured correlations are. In this study, we focus on linearly filtered spike trains and particularly consider correlations caused by overlapping presynaptic neuron populations. We demonstrate that correlation functions and statistical second-order measures like the variance, the covariance, and the correlation coefficient generally exhibit a complex dependence on the filter properties and the statistics of the presynaptic spike trains. We point out that both contributions can play a significant role in modulating the interaction strength between neurons or neuron populations. In many applications, the coherence allows a filter-independent quantification of correlated activity. In different network models, we discuss the estimation of network connectivity from the high-frequency coherence of simultaneous intracellular recordings of pairs of neurons.
Rapid Convergence to Feature Layer Correspondences
Authors: Lücke Jörg , Keck Christian , von der Malsburg Christoph
Published: April 2008

We describe a neural network able to rapidly establish correspondence between neural feature layers. Each of the network's two layers consists of interconnected cortical columns, and each column consists of inhibitorily coupled subpopulations of excitatory neurons. The dynamics of the system builds on a dynamic model of a single column, which is consistent with recent experimental findings. The network realizes dynamic links between its layers with the help of specialized columns that evaluate similarities between the activity distributions of local feature cell populations, are subject to a topology constraint, and can gate the transfer of feature information between the neural layers. The system can robustly be applied to natural images, and correspondences are found in time intervals estimated to be smaller than 100 ms in physiological terms.
Exact Solutions for Rate and Synchrony in Recurrent Networks of Coincidence Detectors
Authors: Mikula Shawn , Niebur Ernst
Published: April 2008

We provide analytical solutions for mean firing rates and cross-correlations of coincidence detector neurons in recurrent networks with excitatory or inhibitory connectivity, with rate-modulated steady-state spiking inputs. We use discrete-time finite-state Markov chains to represent network state transition probabilities, which are subsequently used to derive exact analytical solutions for mean firing rates and cross-correlations. As illustrated in several examples, the method can be used for modeling cortical microcircuits and clarifying single-neuron and population coding mechanisms. We also demonstrate that increasing firing rates do not necessarily translate into increasing cross-correlations, though our results do support the contention that firing rates and cross-correlations are likely to be coupled. Our analytical solutions underscore the complexity of the relationship between firing rates and cross-correlations.
The Russian Civil Code and the Rome Convention: Implied Choice of the Governing Law
Authors: Badykov Mikhail
Published: April 2008

In this article, the author compares the provisions of the 1980 European Convention on the Law Applicable to Contractual Obligations (Rome Convention) and the 1994 Russian Civil Code on implied choice of a governing law (the provisions of Article 3 of the Convention and Article 1210(2) of the Code). He begins with an examination of whether the Code and the Convention allow the use of the same factual data for inferring an implied choice; goes on to analyze whether the relationship between the terms and the circumstances is the same under these two instruments; and concludes by testing whether the Code and the Convention demand the same level of certainty in inferring a choice. This research enriches the methodological background to the rules set forth in Article 1210(2) of the RF Civil Code, as the Russian case law on the subject is quite elementary at present and courts and lawyers, therefore, lack any firm guidance. The author shows that a prima facie similarity in the possible use of terms and circumstances in the Convention and the Code is misleading. Many circumstances that are well-settled under the Convention (e.g., the choice of a particular forum, reference in a contract to a national statute, use of standard forms, etc.) are likely to be ignored in Russia. Furthermore, there is a difference between terms and circumstances in the instruments examined. This difference has its roots in the general provisions of the RF Civil Code (Part I). The implication of a choice in the Code demands such a high standard of certainty that it renders the regulation of the Code substantially different from that of the Convention.
Conditional (Contingent) Fees in the Russian Federation
Authors: Medvedev Andrey
Published: April 2008

In this article, the author discusses contemporary Russian judicial practice concerning the legality of attorney's conditional fees. He starts with a brief overview of foreign practice and distinguishes various kinds of conditional fees. The author provides a classification of conditional fees, through the prism of which he evaluates judicial practice in Russia. He distinguishes and, in particular, contrasts the contingent (or contingency) fee from (with) the conditional fee per se (the conditional fee in the narrow sense). The main focus is on a landmark 2007 Decision of the RF Constitutional Court in which the Court ruled against conditional fees in Russia. The author provides a detailed analysis of the Decision. He supports a view which is in clear opposition to the Constitutional Court, finding the Decision facile, criticizing its motivation and questioning its feasibility. The author describes the claims submitted to the Court, the findings of the Court, and the conclusions reached by the Court. Furthermore, he considers the impact which the Decision may have on judicial practice. The author concludes by discussing the possible future of conditional fees in the Russian Federation and notes that the Decision of the RF Constitutional Court may not constitute the final word on the issue. He advocates further and more in-depth research on the nature of conditional fees.
An Analysis of West African Dynamics Using a Linearized GCM*
Authors: Nicholson S. E. , Barcilon A. I. , Challa M.
Published: April 2008

This study utilizes a linear, primitive equation spherical model to study the development and propagation of easterly wave disturbances over West Africa. Perturbations are started from an initial disturbance consisting of a barotropic vortex and the governing equations are integrated forward in time. The perturbations are introduced into basic states corresponding to the observed dynamical and thermodynamical characteristics of two wet years in the Sahel and two dry years.

The model simulations show consistent contrasts in wave activity between the wet and dry years. The waves are markedly stronger in the wet years and show a barotropic structure throughout the troposphere. The waves tend to extend throughout the troposphere to the level of the tropical easterly jet (TEJ) in the wet years, but not in the dry years. The upper-tropospheric shear, which is stronger in wet years, appears to be a key factor in wave development. This shear is dependent on the intensity of the TEJ, suggesting that the TEJ is an important factor in interannual variability in the Sahel. When the overall shear is weak, vertical development is suppressed.

Another contrast is that in the dry years the growth rates show a single maximum around 3000–4000 km, but in the wet years there is a second, around 6000–7000 km. This suggests that both synoptic-scale and planetary-scale waves are active in the rainy season of some wet years. Imposing considerations of potential vorticity, the generation of planetary-scale waves implies a strong link between the surface and the TEJ in wet years. Such a link is absent in the dry years. This is likely a major factor in the interannual variability of rainfall in the Sahel.
A Barotropic Model of the Angular Momentum–Conserving Potential Vorticity Staircase in Spherical Geometry
Authors: Dunkerton Timothy J. , Scott Richard K.
Published: April 2008

An idealized analytical model of the barotropic potential vorticity (PV) staircase is constructed, constrained by global conservation of absolute angular momentum, perfect homogenization of PV in mixing zones between (prograde) westerly jets, and the requirement of barotropic stability. An imposed functional relationship is also assumed between jet speed and latitudinal separation using a multiple of the “dynamical Rossby wave” Rhines scale inferred from the strength of westerly jets. The relative simplicity of the barotropic system provides a simple relation between absolute angular momentum and PV (or absolute vorticity). A family of solutions comprising an arbitrary number of jets is constructed and is used to illustrate the restriction of jet spacing and strength imposed by the constraints of global conservation of angular momentum and barotropic stability. Asymptotic analysis of the theoretical solution indicates a limiting ratio of jet spacing to the dynamical Rhines scale equal to the square root of 6, meaning that westerly jets are spaced farther apart than predicted by the dynamical Rhines scale. It is inferred that an alternative “geometrical” Rhines scale for jet spacing can be obtained from conservation of absolute angular momentum on the sphere if the strength of zonal jets is known from other considerations. Numerical simulations of the full (nonaxisymmetric) equations reveal a pattern of zonal jet evolution that is consistent with our construction of ideal PV staircases in spherical geometry (which can be considered as limiting cases), as well as with the asymptotic analysis of a geometrical Rhines scale. The evolution of the PV staircase originating from an upscale cascade of energy in the barotropic model is therefore seen to depend on conservation of energy (for the strength of jets) and conservation of absolute angular momentum (for the spacing and number of jets). Further analysis of the numerical results confirms a “Taylor identity” relating the flux of eddy potential vorticity to mean-flow acceleration. Eddy fluxes are responsible for the occasional transitions between mode number as well as for maintaining the sharp westerly jets against small-scale dissipation. Suggestions are made for extending the theoretical model to PV staircases that are asymmetric between hemispheres or with latitudinal variation of amplitude, as modeled in the shallow-water system.
Vertical Transition in Transport and Mixing in Baroclinic Flows
Authors: Greenslade M. D. , Haynes P. H.
Published: April 2008

Numerical simulations in multilevel baroclinic turbulence in a β-plane channel model are discussed, focusing on the transport and mixing behavior. The temperature field in the model is relaxed toward a field consistent with a broad zonal jet with vertical shear that is a Gaussian function of the cross-channel coordinate. The resulting statistical equilibrium flow includes an active baroclinic eddy field. The transport and mixing properties are analyzed by considering the fields of potential vorticity and a passive tracer (from which effective diffusivities/equivalent lengths are calculated). The upper part of the flow organizes itself in such a way that there is a transport barrier in the center of the channel, with eddy mixing regions on either side. In the lower part of the flow the eddy mixing occurs across a single broad region, with no central transport barrier. The transition between these two regimes takes place abruptly at a height zT. A large set of simulations is used to map out the variation of zT as a function of external parameters including β, the thermal relaxation rate κT, and the (lower boundary) frictional relaxation rate κM (applied in the lowest model layer only). The transition height zT is argued to be relevant to sharp vertical transitions in transport and mixing observed in atmospheric and oceanic flows.
Modulation of Small-Scale Turbulence by Ducted Gravity Waves in the Nocturnal Boundary Layer
Authors: Meillier Y. P. , Frehlich R. G. , Jones R. M. , Balsley B. B.
Published: April 2008

Constant altitude measurements of temperature and velocity in the residual layer of the nocturnal boundary layer, collected by the Cooperative Institute for Research in Environmental Sciences (CIRES) Tethered Lifting System (TLS), exhibit fluctuations identified by previous work (Fritts et al.) as the signature of ducted gravity waves. The concurrent high-resolution TLS turbulence measurements (temperature structure constant C2T and turbulent kinetic energy dissipation rate ɛ) reveal the presence of patches of enhanced turbulence activity that are roughly synchronized with the troughs of the temperature and velocity fluctuations. To investigate the potentially dominant role ducted gravity waves might play on the modulation of atmospheric stability and therefore, on turbulence, time series of the wave-modulated gradient Richardson number (Ri) and of the vertical gradient of potential temperature ∂θ/∂z(t) are computed numerically and compared to the TLS small-scale turbulence measurements. The results of this study agree with the predictions of previous theoretical studies (i.e., wave-generated fluctuations of temperature and velocity modulate the gradient Richardson number), resulting in periodic enhancements of turbulence at Ri minima. The patches of turbulence observed in the TLS dataset are subsequently identified as convective instabilities generated locally within the unstable phase of the wave.
Is There a Statistical Connection between Stratospheric Sudden Warming and Tropospheric Blocking Events?
Authors: Taguchi Masakazu
Published: April 2008

This paper presents statistical analyses of possible associations between major stratospheric sudden warming (SSW) and tropospheric blocking events in the Northern Hemisphere (NH) with 49 yr of NCEP–NCAR reanalysis data from 1957/58 to 2005/06. Using a random shuffling or “bootstrap” method, these analyses explore two hypotheses claiming that blocking events occur preferentially and last longer in association with SSWs (pre- and post-SSW periods are considered separately). In the shuffling method, the defined SSWs are randomly redistributed to evaluate the statistical significance of linked cases in the original data. The author’s analyses generally do not support either hypothesis for the pre- or post-SSW period when treating the SSW events all together, suggesting that such associations are not dominant modes of coupling.
A Lagrangian Spectral Parameterization of Gravity Wave Drag Induced by Cumulus Convection
Authors: Song In-Sun , Chun Hye-Yeong
Published: April 2008

A Lagrangian spectral parameterization of gravity wave drag (GWD) induced by cumulus convection (GWDC) is developed based on ray theory and several assumptions and implemented into the NCAR Whole Atmosphere Community Climate Model. The Lagrangian parameterization calculates explicitly gravity wave (GW) propagation that has been treated too simply in existing column-based parameterizations. For comparison with column-based parameterization, a hydrostatic and Boussinesq version of the Lagrangian parameterization is used in the present study. One-day convective GW-packet trajectories demonstrate that the Lagrangian parameterization calculates reasonably the GW-packet propagation, and GW packets propagate upward along curved paths determined by Doppler shifting and the variation of stability. The GW trajectories show that the horizontal extent of GW propagation can be as large as 20° as GWs approach critical levels. Comparison with column-based parameterization through one-month simulations indicates that the magnitude of GWDC is much increased due mainly to the vertical convergence of GW packets in the lower stratosphere and equatorial troposphere with the Lagrangian parameterization. However, this increase in GWDC is found to be essentially dependent on the horizontal propagation characteristics of GWs. In climate simulations, it is found that the easterly flow in the equatorial stratosphere and mesospheric subtropical jet are improved through the Lagrangian parameterization. With the Lagrangian parameterization, interannual variability is significantly enhanced in the equatorial lower stratosphere and exhibits a structure related to the onset of the westerly phase of the stratospheric quasi-biennial oscillations. Finally, limitations of the current Lagrangian parameterization and required improvements are noted.
Using Singular Value Decomposition to Parameterize State-Dependent Model Errors
Authors: Danforth Christopher M. , Kalnay Eugenia
Published: April 2008

The purpose of the present study is to use a new method of empirical model error correction, developed by Danforth et al. in 2007, based on estimating the systematic component of the nonperiodic errors linearly dependent on the anomalous state. The method uses singular value decomposition (SVD) to generate a basis of model errors and states. It requires only a time series of errors to estimate covariances and uses negligible additional computation during a forecast integration. As a result, it should be suitable for operational use at a relatively small computational expense.

The method is tested with the Lorenz ’96 coupled system as the truth and an uncoupled version of the same system as a model. The authors demonstrate that the SVD method explains a significant component of the effect that the model’s unresolved state has on the resolved state and shows that the results are better than those obtained with Leith’s empirical correction operator. The improvement is attributed to the fact that the SVD truncation effectively reduces sampling errors. Forecast improvements of up to 1000% are seen when compared with the original model. The improvements come at the expense of weakening ensemble spread.
Why Precipitation Is Mostly Concentrated over Islands in the Maritime Continent
Authors: Qian Jian-Hua
Published: April 2008

High-resolution observations and regional climate model simulations reveal that precipitation over the Maritime Continent is mostly concentrated over islands. Analysis of the diurnal cycles of precipitation and winds indicates that this is predominantly caused by sea-breeze convergence over islands, reinforced by mountain–valley winds and further amplified by the cumulus merger processes. Comparison of a regional climate model control simulation to a flat-island run and an all-ocean run demonstrates that the underrepresentation of islands and terrain in the Maritime Continent weakens the atmospheric disturbance associated with the diurnal cycle, and hence underestimates precipitation. The implication of these regional modeling results is that systematic errors in coarse-resolution global circulation models probably result from insufficient representation of land–sea breezes associated with the complex topography in the Maritime Continent. It is found that precipitation in the Maritime Continent, simulated by a global model, is indeed smaller than observed. The simulated upper-atmospheric velocity potential, which represents large-scale tropospheric heating, was substantially displaced eastward compared to observations. Possible approaches toward solving this problem are suggested.
Rapid Filamentation Zone in a Numerically Simulated Tropical Cyclone*
Authors: Wang Yuqing
Published: April 2008

In a recent study, Rozoff et al. proposed a possible mechanism to explain the formation and maintenance of the weak-echo annulus (or moat) outside of the primary eyewall of a tropical cyclone observed in radar images. By this mechanism, the moat is determined to be a region of the strain-dominated flow outside of the radius of maximum wind in which essentially all fields are filamented and deep convection is hypothesized to be highly distorted and even suppressed. This strain-dominated region is defined as the rapid filamentation zone wherein the filamentation time is shorter than the overturning time of deep convection. An attempt has been made in this study to test the hypothesis in a full-physics tropical cyclone model under idealized conditions and to extend the concept to the study of the inner-core dynamics of tropical cyclones. The foci of this paper are the evolution of the rapid filamentation zone during the storm intensification, the potential roles of rapid filamentation in the organization of inner spiral rainbands, and the damping of high azimuthal wavenumber asymmetries in the tropical cyclone inner core.

The presented results show that instead of suppressing deep convection, the strain flow in the rapid filamentation zone outside the elevated potential vorticity core provides a favorable environment for the organized inner spiral rainbands, which generally have time scales of several hours, much longer than the typical overturning time scale of individual convective clouds. Although the moat in the simulated tropical cyclone is located in the rapid filamentation zone, it is mainly controlled by the subsidence associated with the overturning flow from eyewall convection and downdrafts from the anvil stratiform precipitation outside of the eyewall. It is thus suggested that rapid filamentation is likely to play a secondary role in the formation of the moat in tropical cyclones. Although the deformation field is determined primarily by the structure of the tropical cyclone, it can have a considerable effect on the evolution of the storm. Because of strong straining deformation, asymmetries with azimuthal wavenumber >4 are found to be damped effectively in the rapid filamentation zone. The filamentation time thus provides a quantitative measure of the stabilization and axisymmetrization of high-wavenumber asymmetries in the inner core by shearing deformation and filamentation.
Large-Eddy Simulations and Observations of Atmospheric Marine Boundary Layers above Nonequilibrium Surface Waves
Authors: Sullivan Peter P. , Edson James B. , Hristov Tihomir , McWilliams James C.
Published: April 2008

Winds and waves in marine boundary layers are often in an unsettled state when fast-running swell generated by distant storms propagates into local regions and modifies the overlying turbulent fields. A large-eddy simulation (LES) model with the capability to resolve a moving sinusoidal wave at its lower boundary is developed to investigate this low-wind/fast-wave regime. It is used to simulate idealized situations with wind following and opposing fast-propagating waves (swell), and stationary bumps. LES predicts momentum transfer from the ocean to the atmosphere for wind following swell, and this can greatly modify the turbulence production mechanism in the marine surface layer. In certain circumstances the generation of a low-level jet reduces the mean shear between the surface layer and the PBL top, resulting in a near collapse of turbulence in the PBL. When light winds oppose the propagating swell, turbulence levels increase over the depth of the boundary layer and the surface drag increases by a factor of 4 compared to a flat surface. The mean wind profile, turbulence variances, and vertical momentum flux are then dependent on the state of the wave field. The LES results are compared with measurements from the Coupled Boundary Layers Air–Sea Transfer (CBLAST) field campaign. A quadrant analysis of the momentum flux from CBLAST verifies a wave age dependence predicted by the LES solutions. The measured bulk drag coefficient CD then depends on wind speed and wave state. In situations with light wind following swell, CD is approximately 50% lower than values obtained from standard bulk parameterizations that have no sea state dependence. In extreme cases with light wind and persistent swell, CD < 0.
Arctic Mixed-Phase Clouds Simulated by a Cloud-Resolving Model: Comparison with ARM Observations and Sensitivity to Microphysics Parameterizations
Authors: Luo Yali , Xu Kuan-Man , Morrison Hugh , McFarquhar Greg
Published: April 2008

Single-layer mixed-phase stratiform (MPS) Arctic clouds, which formed under conditions of large surface heat flux combined with general subsidence during a subperiod of the Atmospheric Radiation Measurement (ARM) Program’s Mixed-Phase Arctic Cloud Experiment (MPACE), are simulated with a cloud-resolving model (CRM). The CRM is implemented with either an advanced two-moment [Morrison et al. (MCK)] or a commonly used one-moment [Lin et al. (LFO)] bulk microphysics scheme and a state-of-the-art radiative transfer scheme.

The MCK simulation, which uses the two-moment scheme and observed aerosol size distribution and ice nulei (IN) number concentration, reproduces the magnitudes and vertical structures of cloud liquid water content (LWC), total ice water content (IWC), and number concentration and effective radius of cloud droplets as suggested by the MPACE observations. The simulation underestimates ice crystal number concentrations by an order of magnitude and overestimates effective radius of ice crystals by a factor of 2–3. The LFO experiment, which uses the one-moment scheme, produces values of liquid water path (LWP) and ice plus snow water path (ISWP) that were about 30% and 4 times, respectively, those produced by MCK. The vertical profile of IWC exhibits a bimodal distribution in contrast to the constant distribution of IWC produced in MCK and observations.

A sensitivity test that uses the same ice–water saturation adjustment scheme as in LFO produces cloud properties that are more similar to the LFO simulation than MCK. The mean value of the intercept parameter of snow size spectra (N0s) from MCK is one order of magnitude smaller than that assumed in LFO. A sensitivity test that prescribes the larger LFO N0s results in 20% less LWP and 5 times larger snow water path than that in MCK. When an exponential ice size distribution replaces the gamma size distribution in MCK, the ISWP decreases by 70% but the LWP increases by 7% versus that in the MCK. Increasing the IN number concentration from the observed value of 0.16 to 3.2 L−1 forces the MPS clouds to become glaciated and dissipate, but the simulated ice number concentration agrees initially with the observations better. Physical explanations for these quantitative differences are provided. It is further shown that the differences between the LFO and MCK results are larger than those due to the estimated uncertainties in the prescribed surface fluxes. Additional observations and simulations of a variety of cases are required to further narrow down uncertainties in the microphysics schemes.
Vertical Motions in Arctic Mixed-Phase Stratiform Clouds
Authors: Shupe Matthew D. , Kollias Pavlos , Persson P. Ola G. , McFarquhar Greg M.
Published: April 2008

The characteristics of Arctic mixed-phase stratiform clouds and their relation to vertical air motions are examined using ground-based observations during the Mixed-Phase Arctic Cloud Experiment (MPACE) in Barrow, Alaska, during fall 2004. The cloud macrophysical, microphysical, and dynamical properties are derived from a suite of active and passive remote sensors. Low-level, single-layer, mixed-phase stratiform clouds are typically topped by a 400–700-m-deep liquid water layer from which ice crystals precipitate. These clouds are strongly dominated (85% by mass) by liquid water. On average, an in-cloud updraft of 0.4 m s−1 sustains the clouds, although cloud-scale circulations lead to a variability of up to ±2 m s−1 from the average. Dominant scales-of-variability in both vertical air motions and cloud microphysical properties retrieved by this analysis occur at 0.5–10-km wavelengths. In updrafts, both cloud liquid and ice mass grow, although the net liquid mass growth is usually largest. Between updrafts, nearly all ice falls out and/or sublimates while the cloud liquid diminishes but does not completely evaporate. The persistence of liquid water throughout these cloud cycles suggests that ice-forming nuclei, and thus ice crystal, concentrations must be limited and that water vapor is plentiful. These details are brought together within the context of a conceptual model relating cloud-scale dynamics and microphysics.
Characteristics of Summer Airflow over the Antarctic Peninsula in Response to Recent Strengthening of Westerly Circumpolar Winds
Authors: Orr Andrew , Marshall Gareth J. , Hunt Julian C. R. , Sommeria Joel , Wang Chang-Gui , van Lipzig Nicole P. M. , Cresswell Doug , King John C.
Published: April 2008

Summer near-surface temperatures over the northeast coast of the Antarctic Peninsula have increased by more than 2°C over the past 40 years, a temperature increase 3 times greater than that on the northwest coast. Recent analysis has shown a strong correlation between this striking warming trend and significant change in the summer Southern Hemisphere annular mode (SAM), which has resulted in greatly increased summer westerlies across the northern peninsula. It has been proposed that the strengthening westerlies have resulted in increased vertical deflection of relatively warm maritime air over the northern peninsula, contributing significantly to the observed warming and the recent collapse of northern sections of the Larsen Ice Shelf. In this study, laboratory and numerical modeling of airflow incident to the peninsula are employed to further understand this mechanism. It is shown that the effect of the strengthening westerlies has led to a distinct transition from a “blocked” regime to a “flow-over” regime, that is, confirmation of the proposed warming mechanism. The blocked regime is dominated by flow stagnation upstream (i.e., little vertical deflection) and consequent lateral deflection of flow along the western side of the peninsula. The flow-over regime is dominated by vertical deflection of mid/upper-level air over the peninsula, with strong downslope winds following closely to the leeward slope transporting this air (which warms adiabatically as it descends) to the near-surface of the northeast peninsula. The strong rotation typical of high latitudes considerably increases the flow over the peninsula, particularly strengthening it over the southern side (verified by aircraft measurements), suggesting that the warming trend is not solely confined to the northeast. Globally, flow regime transitions such as this may be responsible for other local climate variations.
Examining Regional Science Attainment and School—Teacher Resources Using GIS
Authors: Hogrebe Mark C. , Kyei-Blankson Lydia , Zou Li
Published: April 2008

Using percentage of students at proficient and advanced levels for science on the Missouri Assessment Program in St. Louis area school districts, this study investigates the relationship of scientific attainment with school variables of enrollment, percentage of students receiving free/reduced lunch, instructional expenditures per student, teacher/pupil ratio, and teacher variables of percentage with master's degrees, salary, and years of experience. At the district level, the results suggest a significantly large negative correlation between science performance and percentage of students receiving free/ reduced lunch and moderate positive correlations for science attainment with instructional expenditures per student, teacher salary, education, and experience. Geographic information system (GIS) is used to produce spatial and geographic representations of relationships between school, teacher, and science attainment variables. This geospatial representation gives a unique perspective on how educational data are distributed across the region and shows district variation in student science attainment in relationship to where school and teacher resources are located.
Iterations of the SafeCare Model
Authors: Edwards Anna , Lutzker John R.
Published: April 2008

SafeCare is an evidenced-based parenting program for at-risk and maltreating parents that addresses the social and family ecology in which child maltreatment occurs. SafeCare home visitors focus on behavioral skills that are trained to predetermined performance criteria. Recent research has stressed the importance of successful dissemination and implementation of evidence-based models. This article describes the history of the SafeCare model, critical features involved with past and current implementation of the program, populations that have received SafeCare services, staff who have implemented the program, and factors associated with SafeCare implementation. As well, it notes projects currently occurring in Oklahoma and Kansas and at the Center for Child Well-Treatment, at the Marcus Institute, in Atlanta, Georgia.
On Being Eager and Uninhibited: Narcissism and Approach–Avoidance Motivation
Authors: Foster Joshua D. , Trimm Riley F.
Published: April 2008

This article demonstrates the validity and utility of conceptualizing narcissistic personality in terms of relative approach–avoidance motivation. Across three studies (N = 1,319), narcissism predicted high approach and low avoidance motivation. That is, narcissists reported being strongly motivated to approach desirable outcomes but only weakly motivated to avoid negative outcomes. Relative approach–avoidance motivation was shown to be useful in terms of explaining behavioral tendencies associated with narcissism (i.e., functional and dysfunctional impulsivity) and distinguishing different “flavors” of narcissism (i.e., overt and covert narcissism). Discussion focuses on how approach–avoidance motivation may be used to explain prior findings in the narcissism literature and generate novel future hypotheses.
Results of a prospective pilot trial on mobility after whole body vibration in children and adolescents with osteogenesis imperfecta
Authors: Semler Oliver , Fricke Oliver , Vezyroglou Katharina , Stark Christina , Stabrey Angelika , Schoenau Eckhard
Published: April 2008

Objective: To evaluate the effect of whole body vibration on the mobility of long-term immobilized children and adolescents with a severe form of osteogenesis imperfecta. Osteogenesis imperfecta is a hereditary primary bone disorder with a prevalence from 1 in 10000 to 1 in 20000 births. Most of these children are suffering from long-term immobilization after recurrent fractures. Due to the immobilization they are affected by loss of muscle (sarcopenia) and secondary loss of bone mass.

Subjects: Whole body vibration was applied to eight children and adolescents (osteogenesis imperfecta type 3, N=5; osteogenesis imperfecta type 4, N=3) over a period of six months.

Interventions and results: Whole body vibration was applied by a vibrating platform (Galileo Systems) constructed on a tilting-table. Success of treatment was assessed by measuring alterations of the tilting-angle and evaluating the mobility (Brief Assessment of Motor Function). All individuals were characterized by improved muscle force documented by an increased tilting-angle (median = 35 degrees) or by an increase in ground reaction force (median at start=30.0 [N/kg] (14.48—134.21); median after six months = 146.0 [N/kg] (42.46—245.25).

Conclusions: Whole body vibration may be a promising approach to improve mobility in children and adolescents severely affected with osteogenesis imperfecta.
Serial casting versus positioning for the treatment of elbow contractures in adults with traumatic brain injury: a randomized controlled trial
Authors: Moseley Anne M , Hassett Leanne M , Leung Joan , Clare Jennifer S , Herbert Robert D , Harvey Lisa A
Published: April 2008

Objective: To compare the effects of serial casting with positioning for 1 hour per day for the treatment of elbow flexion contracture in adults with traumatic brain injury.

Design: Pragmatic randomized controlled trial with concealed allocation and assessor blinding.

Setting: Four brain injury rehabilitation units.

Subjects: Twenty-six adults with elbow flexion contracture after traumatic brain injury participating in multidisciplinary inpatient rehabilitation.

Interventions: Subjects were randomized to receive either serial casting or positioning for two weeks. In the subsequent four weeks subjects could be positioned for up to 1 hour/day.

Main measures: Torque-controlled passive elbow extension was measured at baseline, post-intervention (two weeks), post-intervention plus one day, and at follow-up (four weeks post-intervention).

Results: All 26 subjects completed the study. Post-intervention, serial casting reduced contracture by an average of 22 degrees (95% confidence interval (CI) 13 to 31; P <0.001) compared with the positioning group. One day later this effect had decreased to 11 degrees (95% CI 0 to 21 degrees; P= 0.052). The effect had almost completely disappeared at the four-week follow-up (mean 2 degrees, 95% CI -13 to 17; P= 0.782).

Conclusions: Serial casting induces transient increases in range of motion. These effects are not maintained.
Can exercise limits prevent post-exertional malaise in chronic fatigue syndrome? An uncontrolled clinical trial
Authors: Nijs Jo , Almond Freya , De Becker Pascale , Truijen Steven , Paul Lorna
Published: April 2008

Objective: It was hypothesized that the use of exercise limits prevents symptom increases and worsening of their health status following a walking exercise in people with chronic fatigue syndrome.

Design: An uncontrolled clinical trial (semi-experimental design).

Setting: Outpatient clinic of a university department.

Subjects: Twenty-four patients with chronic fatigue syndrome.

Interventions: Subjects undertook a walking test with the two concurrent exercise limits. Each subject walked at an intensity where the maximum heart rate was determined by heart rate corresponding to the respiratory exchange ratio = 1.0 derived from a previous submaximal exercise test and for a duration calculated from how long each patient felt they were able to walk.

Main outcome measures: The Short Form 36 Health Survey or SF-36, the Chronic Fatigue Syndrome Symptom List, and the Chronic Fatigue Syndrome — Activities and Participation Questionnaire were filled in prior to, immediately after and 24 hours after exercise.

Results: The fatigue increase observed immediately post-exercise (P= 0.006) returned to pre-exercise levels 24 hours post-exercise. The increase in pain observed immediately post-exercise was retained at 24 hours post-exercise (P=0.03). Fourteen of the 24 subjects experienced a clinically meaningful change in bodily pain (change of SF-36 bodily pain score ≥10); 6 indicated that the exercise bout had slightly worsened their health status, and 2 had a clinically meaningful decrease in vitality (change of SF-36 vitality score ≥20). There was no change in activity limitations/participation restrictions.

Conclusion: It was shown that the use of exercise limits (limiting both the intensity and duration of exercise) prevents important health status changes following a walking exercise in people with chronic fatigue syndrome, but was unable to prevent short-term symptom increases.
Short- and long-term outcome of constraint-induced movement therapy after stroke: a randomized controlled feasibility trial
Authors: Dahl AE , Askim T. , Stock R. , Langørgen E. , Lydersen S. , Indredavik B.
Published: April 2008

Objective: Constraint-induced movement therapy (CIMT) is a method to improve motor function in the upper extremity following stroke. The aim of this trial was to determine the effect and feasibility of CIMT compared with traditional rehabilitation in short and long term.

Design: A randomized controlled trial.

Setting: An inpatient rehabilitation clinic.

Subjects: Thirty patients with unilateral hand impairment after stroke.

Intervention: Six hours arm therapy for 10 consecutive weekdays, while

using a restraining mitten on the unaffected hand.

Main measures: The patients were assessed at baseline, post-treatment and at six-month follow-up using the Wolf Motor Function Test as primary outcome measure and the Motor Activity Log, Functional Independence Measure and Stroke Impact Scale as secondary measurements.

Results: The CIMT group (n=18) showed a statistically significant shorter performance time (4.76 seconds versus 7.61 seconds, P= 0.030) and greater functional ability (3.85 versus 3.47, P= 0.037) than the control group (n=12) on the Wolf Motor Function Test at post-treatment assessment. There was a non-significant trend toward greater amount of use (2.47 versus 1.97, P= 0.097) and better quality of movement (2.45 versus 2.12, P=0.105) in the CIMT group according to the Motor Activity Log. No such differences were seen on Functional Independence Measure at the same time. At six-month follow-up the CIMT group maintained their improvement, but as the control group improved even more, there were no significant differences between the groups on any measurements.

Conclusions: CIMT seems to be an effective and feasible method to improve motor function in the short term, but no long-term effect was found.
The effects of sensorimotor training on knee proprioception and function for patients with knee osteoarthritis: a preliminary report
Authors: Tsauo Jau-Yih , Cheng Pai-Fu , Yang Rong-Sen
Published: April 2008

Objective: To investigate the effects of a sensorimotor training programme in osteoarthritic patients.

Design: Randomized, single-blind, controlled trial.

Setting: Kinesiology laboratory at School of Physical Therapy.

Participants: A total of 60 patients were randomly assigned to the training group and the control group. Only 29 patients (training group, 15; control group, 14) completed the study.

Intervention: The training group underwent a sensorimotor training programme using a sling suspension system complemented by a routine physical therapy. The control group underwent a routine physical therapy.

Main measures: Active joint repositioning, functional testings, and self-reported function with the Western Ontario & McMaster Universities Arthritis Index before and after the eight-week intervention.

Results: There were significant differences between the two groups with respect to the improvement in proprioception as measured by active joint repositioning (the changes in the absolute error were 1.9± 1.7°, training group versus 0.1 ± 2.8°, control group (P<0.05), and in self-reported functional difficulty (33.2 ±35.1, training group versus 8.0± 10.2, control group; P<0.05)). There was no significant difference between the two groups in other outcomes.

Conclusion: A sensorimotor training using a sling suspension system improved the patients' proprioception in the knee joints and their self-reported function. Thus, these exercises may serve as an exercise programme for patients with knee osteoarthritis.
An exploratory randomized controlled trial of assisted practice for improving sit-to-stand in stroke patients in the hospital setting
Authors: Britton Elizabeth , Harris Nigel , Turton Ailie
Published: April 2008

Objectives: To evaluate the amount of practice achieved and assess potential for effects on performance of 30 minutes of daily training in sit-to-stand.

Design: Randomized controlled pilot study.

Setting: Stroke rehabilitation unit, UK.

Participants: Eighteen stroke patients needing `stand by' help to sit-to-stand.

Interventions: In addition to usual rehabilitation the experimental group (n = 9) practised sit-to-stand and leg strengthening exercises for 30 minutes, on weekdays for two weeks, with a physiotherapy assistant. The control group received arm therapy.

Main outcome measures: Frequency of sit-to-stands per day. Performance measures: rise time, weight taken through the affected foot at `thighs off', number of attempts needed to achieve three successful sit-to-stands and the number of sit-to-stands performed in 60 seconds. Outcome was measured one and two weeks after baseline assessment.

Results: Sit-to-stand frequency averaged 18 per day. Thirty minutes of practice in sit-to-stand resulted in a mean of 50 (SD 17.2) extra stands per day. There was a significant mean difference of 10% body weight taken through the affected foot after one week of intervention: The control group had reduced weight through the affected leg while the training group increased weight (F1,16 = 11.1, P= 0.004, 95% confidence interval (CI) -16.61 to -3.72). No significant differences between groups were found on other measures. Results two weeks after baseline were inconclusive due to loss of five participants.

Conclusions: Task-specific practice given for 30 minutes a day appears promising for patients learning to sit-to-stand.