bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Information Content of Infrared Sounding Radiances in Cloudy Conditions
Authors: Koyama T. , Vukicevic T. , Sengupta M. , Vonder Haar T. , Jones A. S.
Published: December 2006

Information content analysis of the Geostationary Operational Environmental Satellite (GOES) sounder observations in the infrared was conducted for use in satellite data assimilation. Information content is defined as a first-order response of the top-of-atmosphere brightness temperature to perturbations of simulated temperature and humidity profiles, obtained from a cloud-resolving model, both in the presence and absence of clouds. Sensitivity to the perturbations was numerically evaluated using an observational operator for visible and infrared radiative transfer developed within a research satellite data assimilation system. The vertical distribution of the sensitivities was analyzed as a function of cloud optical thickness covering the range from a cloud-free scene to an optically thick cloud. The clear-sky sensitivities to temperature and humidity perturbations for each channel are representative of the corresponding channel weighting functions for a clear-sky case. For optically thin–moderate ice clouds, the vertical distributions of the sensitivities resemble clear-sky results, indicating that the use of infrared sounding observations in data assimilation can potentially improve temperature and humidity profiles below those clouds. This result is significant, as GOES infrared sounder data have until now only been used in cloud-cleared scenes. It is expected that the use of sounder data in data assimilation, even in the presence of optically thin to moderate high clouds, will help reduce errors in temperature and water vapor mixing ratio profiles below the clouds.
Using Stochastically Generated Subcolumns to Represent Cloud Structure in a Large-Scale Model
Authors: Pincus Robert , Hemler Richard , Klein Stephen A.
Published: December 2006

A new method for representing subgrid-scale cloud structure in which each model column is decomposed into a set of subcolumns has been introduced into the Geophysical Fluid Dynamics Laboratory’s global atmospheric model AM2. Each subcolumn in the decomposition is homogeneous, but the ensemble reproduces the initial profiles of cloud properties including cloud fraction, internal variability (if any) in cloud condensate, and arbitrary overlap assumptions that describe vertical correlations. These subcolumns are used in radiation and diagnostic calculations and have allowed the introduction of more realistic overlap assumptions. This paper describes the impact of these new methods for representing cloud structure in instantaneous calculations and long-term integrations. Shortwave radiation computed using subcolumns and the random overlap assumption differs in the global annual average by more than 4 W m−2 from the operational radiation scheme in instantaneous calculations; much of this difference is counteracted by a change in the overlap assumption to one in which overlap varies continuously with the separation distance between layers. Internal variability in cloud condensate, diagnosed from the mean condensate amount and cloud fraction, has about the same effect on radiative fluxes as does the ad hoc tuning accounting for this effect in the operational radiation scheme. Long simulations with the new model configuration show little difference from the operational model configuration, while statistical tests indicate that the model does not respond systematically to the sampling noise introduced by the approximate radiative transfer techniques introduced to work with the subcolumns.
Characteristics of African Easterly Waves Depicted by ECMWF Reanalyses for 1991–2000
Authors: Chen Tsing-Chang
Published: December 2006

Several interesting characteristics of African easterly waves (AEWs) were observed and investigated by previous studies: two separate propagation paths, genesis mechanisms, restriction of vertical development, and the interaction with the African easterly jet (AEJ). However, some aspects of these characteristics have been neglected: the contrast of the AEW population along the two propagation paths, the AEW genesis mechanism over the Saharan thermal low and the role played by the low-level North African circulation in this mechanism, the dynamical mechanism restricting the vertical development of AEWs, and the synoptic relationship and interaction between the AEJ and the AEWs along the two propagation paths. The ECMWF reanalyses for the 1991–2000 period supplemented with those of 1979 were analyzed to explore these AEW features. Major findings of this effort are the following:

The population of AEWs along the propagation path north of the AEJ (AEWn) is approximately 2.5 times of that along the propagation path south of the AEJ (AEWs). The AEWn geneses primarily occur over the three convergent centers and the southwestward extension of the Saharan thermal low. Underneath the midtropospheric Saharan high, the baroclinic instability of a shallow, low static stability environment, which may be triggered by the intrusion of dry northerlies over central North Africa, leads to the AEW genesis. Continental-scale upward motion along the Saharan thermal low and the cyclonic-shear side of the AEJ maintains positive vortex stretching below the Saharan high and the western part of the Asian monsoon high. These two regions thus form a favorable environment for the development of AEWs within the near-surface troposphere along the Saharan thermal low and the midtroposphere south of the AEJ. The passage of AEWn (AEWs) across the coastal zone of West Africa is accompanied by a weak (strong) AEJ and weak (strong) Saharan high. The westward propagation and development/maintenance of the two types of AEWs are achieved through vorticity advection by the AEJ, which is the major AEW–AEJ interaction. These findings will facilitate the search for AEW dynamics and aid in assessing the impact of AEW activity on North African climate change.
Synoptic–Dynamic Climatology of Large-Scale Cyclones in the North Pacific
Authors: Keller Linda M. , Morgan Michael C. , Houghton David D. , Lazear Ross A.
Published: December 2006

A climatology of large-scale, persistent cyclonic flow anomalies over the North Pacific was constructed using the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) global reanalysis data for the cold season (November–March) for 1977–2003. These large-scale cyclone (LSC) events were identified as those periods for which the filtered geopotential height anomaly at a given analysis point was at least 100 m below its average for the date for at least 10 days. This study identifies a region of maximum frequency of LSC events at 45°N, 160°W [key point 1 (KP1)] for the entire period. This point is somewhat to the east of regions of maximum height variability noted in previous studies. A second key point (37.5°N, 162.5°W) was defined as the maximum in LSC frequency for the period after November 1988. The authors show that the difference in location of maximum LSC frequency is linked to a climate regime shift at about that time. LSC events occur with a maximum frequency in the period from November through January.

A composite 500-hPa synoptic evolution, constructed relative to the event onset, suggests that the upper-tropospheric precursor for LSC events emerges from a quasi-stationary long-wave trough positioned off the east coast of Asia. In the middle and lower troposphere, the events are accompanied by cold thickness advection from a thermal trough over northeastern Asia. The composite mean sea level evolution reveals a cyclone that deepens while moving from the coast of Asia into the central Pacific. As the cyclone amplifies, it slows down in the central Pacific and becomes nearly stationary within a day of onset. Following onset, at 500 hPa, a stationary wave pattern, resembling the Pacific–North American teleconnection pattern, emerges with a ridge immediately downstream (over western North America) and a trough farther downstream (from the southeast coast of the United States into the western North Atlantic). The implications for the resulting sensible weather and predictability of the flow are discussed. An adjoint-derived sensitivity study was conducted for one of the KP1 cases identified in the climatology. The results provide dynamical confirmation of the LSC precursor identification for the events. The upper-tropospheric precursor is seen to play a key role not only in the onset of the lower-tropospheric height falls and concomitant circulation increases, but also in the eastward extension of the polar jet across the Pacific. The evolution of the forecast sensitivities suggest that LSC events are not a manifestation of a modal instability of the time mean flow, but rather the growth of a favorably configured perturbation on the flow.
Dynamics of Track Deflection Associated with the Passage of Tropical Cyclones over a Mesoscale Mountain
Authors: Lin Yuh-Lang , Witcraft Nicholas C. , Kuo Ying-Hwa
Published: December 2006

In this study, the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) was used to simulate Supertyphoon Bilis (in 2000) and Typhoon Toraji (in 2001) in order to investigate the dynamics of track deflection caused by the Central Mountain Range (CMR) of Taiwan. The MM5 predicted the track of each storm reasonably well. Bilis was stronger and had a relatively faster forward motion, which helped make the track continuous as it crossed the CMR. The use of a “bogus” vortex in the initialization process helped produce a storm closer to the observed strength. Bilis is a classic example of a typhoon crossing Taiwan with a continuous track. For comparison, Typhoon Toraji, a typical typhoon having a discontinuous track, was also studied. Toraji was weaker and had a relatively slower forward speed, which prevented the original low center from crossing over the CMR and forced more air parcels to go around the northern tip of the CMR. As a result, it produced a vortex and a secondary low center on the lee. Potential vorticity banners on the north side of the CMR acted to organize the secondary low and the lee vortex. With time, the low-level circulation extended into the upper levels, completing the formation of the secondary center. Remnants of the initial center crossed over the CMR and were entrained into the secondary center. Nondimensional control parameters for track continuity and deflection from idealized studies are calculated for Bilis and Toraji. The results are consistent with the theory proposed in Lin et al. For tropical cyclones (TCs) approaching Taiwan from the southeast, the conceptual model proposed by Lin et al. for continuous and discontinuous tracks was applied. For continuous tracks over the CMR, the blocking effect on the outer circulation of the vortex is weak and the vorticity advection around the northern tip is strong due to an intense TC. Weak TCs tend to be totally blocked by the CMR.
Evaluation of the NCEP Global Forecast System at the ARM SGP Site
Authors: Yang Fanglin , Pan Hua-Lu , Krueger Steven K. , Moorthi Shrinivas , Lord Stephen J.
Published: December 2006

This study evaluates the performance of the National Centers for Environmental Prediction Global Forecast System (GFS) against observations made by the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) Program at the southern Great Plains site for the years 2001–04. The spatial and temporal scales of the observations are examined to search for an optimum approach for comparing grid-mean model forecasts with single-point observations. A single-column model (SCM) based upon the GFS was also used to aid in understanding certain forecast errors. The investigation is focused on the surface energy fluxes and clouds. Results show that the overall performance of the GFS model has been improving, although certain forecast errors remain. The model overestimated the daily maximum latent heat flux by 76 W m−2 and the daily maximum surface downward solar flux by 44 W m−2, and underestimated the daily maximum sensible heat flux by 44 W m−2. The model’s surface energy balance was reached by a cancellation of errors. For clouds, the GFS was able to capture the observed evolutions of cloud systems during major synoptic events. However, on average, the model largely underestimated cloud fraction in the lower and midtroposphere, especially for daytime nonprecipitating low clouds because shallow convection in the GFS does not produce clouds. Analyses of surface radiative fluxes revealed that the diurnal cycle of the model’s surface downward longwave flux (SDLW) was not in phase with that of the ARM-observed SDLW. SCM experiments showed that this error was caused by an inaccurate scaling factor, which was a function of ground skin temperature and was used to adjust the SDLW at each model time step to that computed by the model’s longwave radiative transfer routine once every 3 h. A method has been proposed to correct this error in the operational forecast model. It was also noticed that the SDLW biases changed from mostly negative in 2003 to slightly positive in 2004. This change was traced back to errors in the near-surface air temperature. In addition, the SDLW simulated with the newly implemented Rapid Radiative Transfer Model longwave routine in the GFS is usually 5–10 W m−2 larger than that simulated with the previous routine. The forecasts of surface downward shortwave flux (SDSW) were relatively accurate under clear-sky conditions. The errors in SDSW were primarily caused by inaccurate forecasts of cloud properties. Results from this study can be used as guidance for the further development of the GFS.
Simulated Physical Mechanisms Associated with Climate Variability over Lake Victoria Basin in East Africa
Authors: Anyah Richard O. , Semazzi Fredrick H. M. , Xie Lian
Published: December 2006

A fully coupled regional climate, 3D lake modeling system is used to investigate the physical mechanisms associated with the multiscale variability of the Lake Victoria basin climate. To examine the relative influence of different processes on the lake basin climate, a suite of model experiments were performed by smoothing topography around the lake basin, altering lake surface characteristics, and reducing or increasing the amount of large-scale moisture advected into the lake region through the four lateral boundaries of the model domain. Simulated monthly mean rainfall over the basin is comparable to the satellite (Tropical Rainfall Measuring Mission) estimates. Peaks between midnight and early morning hours characterize the simulated diurnal variability of rainfall over the four quadrants of the lake, consistent with satellite estimates, although the simulated peaks occur a little earlier. It is evident in the simulations with smoothed topography that the upslope/downslope flow generated by the mountains east of the lake and the land–lake breeze circulations play important roles in influencing the intensity, the location of lake/land breeze fronts, and the horizontal extent of the land–lake breeze circulation, as well as lake basin precipitation. When the lake surface is replaced with marsh (water hyacinth), the late night and early morning rainfall maximum located over the western sector of the lake is dramatically reduced. Our simulations also indicate that large-scale moisture transported via the prevailing easterly trades enhances lake basin precipitation significantly. This is in contrast to the notion advanced in some of the previous studies that Lake Victoria generates its own climate (rainfall) through precipitation–evaporation–reprecipitation recycling only.
An Improved Calculation of Coriolis Terms on the C Grid
Authors: Dobricic Srdjan
Published: December 2006

The central differencing grid with fully staggered velocity components (C grid) is widely used in primitive equation oceanographic models despite potential problems in simulating baroclinic inertia–gravity and Rossby waves that can arise due to the averaging of velocity components in the Coriolis terms. This note proposes a new averaging of the velocity components in order to calculate the Coriolis terms on the C grid. The averaging weights are calculated from the minimum of a suitably defined cost function that optimally minimizes the error in the inertial part of frequencies of inertia–gravity waves and maintains the second-order accuracy of the computations. The theoretical analysis of wave frequency diagrams shows that the new scheme results in more accurate frequencies of long inertia–gravity and Rossby waves, especially when the Rossby radius of deformation is not well resolved by the grid resolution.
Photographic Documentation and Environmental Analysis of an Intense, Anticyclonic Supercell on the Colorado Plains
Authors: Edwards Roger , Hodanish Stephen J.
Published: December 2006

Anticyclonic left-moving supercells are observed each year in the United States, emanating both discretely and from storm splitting processes. Such thunderstorms often produce severe hail and wind gusts and, on rare occasion, tornadoes. The body of documentary literature on this subset of supercells is relatively scant compared with right-moving storms, and this is especially true regarding visual characteristics and conceptual models. Here a characteristic example of the anticyclonic supercell is presented using an intense and well-defined specimen that passed over Aroya, Colorado, on 15 June 2002. Photographic and radar documentation is provided in original and mirrored forms, for aid in conceptualizing the left-moving supercell and associated structures and processes. A summary overview is presented of the environment, development, evolution, and effects of this remotely located but noteworthy event.
Rapid Scan Views of Convectively Generated Mesovortices in Sheared Tropical Cyclone Gustav (2002)
Authors: Hendricks Eric A. , Montgomery Michael T.
Published: December 2006

On 9–10 September 2002, multiple mesovortices were captured in great detail by rapid scan visible satellite imagery in subtropical, then later, Tropical Storm Gustav. These mesovortices were observed as low-level cloud swirls while the low-level structure of the storm was exposed due to vertical shearing. They are shown to form most plausibly via vortex tube stretching associated with deep convection; they become decoupled from the convective towers by vertical shear; they are advected with the low-level circulation; finally they initiate new hot towers on their boundaries. Partial evidence of an axisymmetrizing mesovortex and its hypothesized role in the parent vortex spinup is presented. Observations from the mesoscale and synoptic scale are synthesized to provide a multiscale perspective of the intensification of Gustav that occurred on 10 September. The most important large-scale factors were the concurrent relaxation of the 850–200-hPa-deep layer vertical wind shear from 10–15 to 5–10 m s−1 and movement over pockets of very warm sea surface temperatures (approximately 29.5°–30.5°C). The mesoscale observations are not sufficient alone to determine the precise role of the deep convection and mesovortices in the intensification. However, qualitative comparisons are made between the mesoscale processes observed in Gustav and recent full-physics and idealized numerical simulations to obtain additional insight.
A Simple and Flexible Method for Ranking Severe Weather Events
Authors: Doswell C. A. , Edwards R. , Thompson R. L. , Hart J. A. , Crosbie K. C.
Published: December 2006

The notion of an “outbreak” of severe weather has been used for decades, but has never been formally defined. There are many different criteria by which outbreaks can be defined based on severe weather occurrence data, and there is not likely to be any compelling logic to choose any single criterion as ideal for all purposes. Therefore, a method has been developed that uses multiple variables and allows for considerable flexibility. The technique can be adapted easily to any project that needs to establish a ranking of weather events. The intended use involves isolating the most important tornado outbreak days, as well as important outbreak days of primarily nontornadic severe convective weather, during a period when the number of reports has been growing rapidly from nonmeteorological factors. The method is illustrated for both tornadic and primarily nontornadic severe weather event day cases. The impact of the secular trends in the data has been reduced by a simple detrending scheme. The effect of detrending is less important for the tornado outbreak cases and is illustrated by comparing rankings with and without detrending. It is shown that the resulting rankings are relatively resistant to secular trends in the data, as intended, and not strongly sensitive to the choices made in applying the method. The rankings are also consistent with subjective judgments of the relative importance of historical tornado outbreak cases.
Comparing Local Analysis and Prediction System (LAPS) Assimilations with Independent Observations
Authors: Hiemstra Christopher A. , Liston Glen E. , Pielke Roger A. , Birkenheuer Daniel L. , Albers Steven C.
Published: December 2006

Meteorological forcing data are necessary to drive many of the spatial models used to simulate atmospheric, biological, and hydrological processes. Unfortunately, many domains lack sufficient meteorological data and available point observations are not always suitable or reliable for landscape or regional applications. NOAA’s Local Analysis and Prediction System (LAPS) is a meteorological assimilation tool that employs available observations (meteorological networks, radar, satellite, soundings, and aircraft) to generate a spatially distributed, three-dimensional representation of atmospheric features and processes. As with any diagnostic representation, it is important to ascertain how LAPS outputs deviate from a variety of independent observations. A number of surface observations exist that are not used in the LAPS system, and they were employed to assess LAPS surface state variable and precipitation analysis performance during two consecutive years (1 September 2001–31 August 2003). LAPS assimilations accurately depicted temperature and relative humidity values. The ability of LAPS to represent wind speed was satisfactory overall, but accuracy declined with increasing elevation. Last, precipitation estimates performed by LAPS were irregular and reflected inherent difficulties in measuring and estimating precipitation.
Tornadoes with Cold Core 500-mb Lows
Authors: Davies Jonathan M.
Published: December 2006

Tornadoes that occur in close proximity to midlevel closed lows with a core of cold temperatures aloft are not uncommon, particularly in the central United States. Although several informal studies have shown that severe weather and tornadoes can occur with these midlevel lows, little in the way of formal work has been published documenting features and ingredients of such systems, especially those that produce what are sometimes called cold core tornadoes. Of particular concern is that these tornadoes can be associated with surface and low-level moisture that appears deceptively small or marginal regarding severe weather potential, yet on occasion tornadoes of F2 or greater intensity can develop. In other cases, vertical shear may appear relatively weak at locations close to the midlevel low, suggesting little potential for tornadoes. These “atypical” characteristics can result in poor anticipation by forecasters of tornado events associated with closed 500-mb lows. This note documents some synoptic and mesoscale features commonly associated with tornado events in close proximity to cold core 500-mb lows using four tornadic cases in Kansas as examples, including photographs to show the small nature of storms associated with such systems. Recognition of surface patterns with a particular organization of boundaries and surface heating positioned near midlevel lows, along with the presence of some amount of buoyancy, can help with the operational awareness of the potential for tornadoes in many 500-mb closed low settings.
Linear and Nonlinear Statistical Downscaling for Rainfall Forecasting over Southeastern Brazil
Authors: Ramírez María CleoféValverde , Ferreira Nelson Jesus , Velho Haroldo Fragade Campos
Published: December 2006

In this work linear and nonlinear downscaling are developed to establish empirical relationships between the synoptic-scale circulation and observed rainfall over southeastern Brazil. The methodology uses outputs from the regional Eta Model; prognostic equations for local forecasting were developed using an artificial neural network (ANN) and multiple linear regression (MLR). The final objective is the application of such prognostic equations to Eta Model output to generate rainfall forecasts. In the first experiment the predictors were obtained from the Eta Model and the predictand was rainfall data from meteorological stations in southeastern Brazil. In the second experiment the observed rainfall on the day prior to the forecast was included as a predictor. The threat score (TS) and bias, used to quantify the performance of the forecasts, showed that the ANN was superior to MLR in most seasons. When compared with Eta Model forecasts, it was observed that the ANN has a tendency to forecast moderate and high rainfall with greater accuracy during the austral summer. Also, when the observed rainfall of the previous day is included as a predictor, the TS showed the best performance in continuous rain and well-organized meteorological systems. On the other hand, in the austral winter period, characterized by slight rain, the ANN showed better forecasting ability than did the Eta Model. The obtained results also suggest that in the austral winter rainfall is more predictable because convection is less frequent, and when this occurs the forcing is dynamic instead of thermodynamic.
Effects of Fibers' Alkali Treatment on the Resin Transfer Molding Processing and Mechanical Properties of Jute—Vinylester Composites
Authors: Rodriguez Exequiel S. , Stefani Pablo M. , Vazquez Analia
Published: December 2006

The aim of this paper is to evaluate the effect of the alkali treatment on the mechanical properties of jute fibers and its composites. The effect on the processing conditions was also analyzed. Woven jute preforms were used to prepare the composites using the vacuum infusion technique. The fibers were treated with NaOH (5wt.%) for 24 h at room temperature. Single filament tests showed that the treatment was detrimental for the mechanical properties of the fibers. The injection times increased in the treated jute preforms as a consequence of the increase in the exposed area and the flow resistance. The preform permeability decreased, also, in the tubular structure collapse of the fibers, which could reduce the capillary pressure. Flexural and impact properties of the treated jute composites decreased mainly in the lower mechanical properties of the fibers.
Multi-scale Analyses of 3D Woven Composite Based On Periodicity Boundary Conditions
Authors: Wang X.F. , Wang X.W. , Zhou G.M. , Zhou C.W.
Published: December 2006

In this article, two-scale 3D finite element (FE) models, the microscopic repeated unit cell (RUC) model for yarn, and mesoscopic-repeated unit cell model for woven composite, are presented to predict the effective stiffness properties of 3D woven orthogonal interlock composites. The micro-RUC model for the yarn is based on a hexagonal array of fibers. Undulation of the yarns in the novel 3-D meso-RUC for the woven composite is described by Hermit-spline function. The periodic boundary conditions are applied to the two-scale models during the 3D FE analysis in order to ensure that both the displacement and stress are continuous on the boundary surfaces. Specimens are manufactured with house-made resin transfer molding (RTM) equipment and simple tensile experiment is performed. It is found that the predicted yarn properties by the micro-RUC agree well with data computed by equations with a suitable parameter determined by experiment and the predicted effective stiffness properties of 3-D woven composites by the meso-RUC are also in good agreement with the test data. Thus the correctness of the established multi-scale models and analysis method are verified.
Smart Concrete with Embedded Piezoelectric Devices: Implementation and Characterization
Authors: Wen Yumei , Chen Yu , Li Ping , Jiang Deyi , Guo Hao
Published: December 2006

A scheme for monitoring concrete structures, by embedding PZT ceramics into concrete modules has been proposed previously. These modules can be used as building blocks in the infrastructure engineering. Owing to the piezoelectric device embedment, the blocks are sensitive to ambient condition changes including stress, temperature, and humidity. It is suggested that by measuring the equivalent circuit parameters of embedded piezoelectric ceramics, the structural-static or quasi-static state may be interrogated. The equivalent circuit parameters of a piezoelectric device represent the characteristics of the piezoelectric, dielectric, and mechanical performances. By analyzing the parameters, the signal related to the structural-mechanical state can be acquired. Theoretically, a piezoelectric device can be modeled as a multiple-input-multiple-output transducer. In practice, the problem remains that the equivalent parameters, the sensing outputs, are also dependent on the ambient settings such as temperature which may cause either expansion or shrinkage. However, through dozens of experiments with smart concrete specimens embedded with piezoelectric elements and piezoelectric elements free of embedment, it is observed that the characteristic frequencies (anti-resonance and resonance) are quite sensitive to temperature but have little dependence on stress. This way, by sensing data fusion, the characteristic frequencies are used as temperature indicators to remove the variation in equivalent circuit parameters resulting from temperature, exclusive of using additional sensors for compensation. In turn, the structural stress-monitoring (static or quasi-static) through the detection of the equivalent circuit parameters is achieved.
Analysis of SMA Hybrid Composite Structures in MSC.Nastran and ABAQUS
Authors: Turner Travis L. , Patel Hemant D.
Published: December 2006

A thermoelastic constitutive model for shape memory alloy (SMA) actuators embedded in a composite structure, termed an SMA hybrid composite (SMAHC), was recently implemented in the commercial finite element codes MSC.Nastran and ABAQUS. The model can be easily implemented in any code that has the capability for analysis of laminated composite structures with temperature-dependent material properties. The model is also relatively easy to use, and requires input of only fundamental engineering properties. A brief description of the model is presented, followed by a discussion of implementation and usage in commercial codes. Results are presented from static and dynamic analysis of SMAHC beams of two types: a beam clamped at each end and a cantilever beam. Nonlinear static (post-buckling) and random response analyses are demonstrated for the first specimen. Static deflection (shape) control is demonstrated for the cantilever beam. Approaches for modeling SMAHC material systems with embedded SMA in ribbon and small round wire product forms are demonstrated and compared. The results from commercial codes are compared with those from a research code as validation of commercial implementations; excellent correlation is achieved in all the cases.
Exploiting Functional Fibers in Advanced Composite Materials
Authors: Etches Julie A. , Scholey Jonathan J. , Williams Gareth J. , Bond Ian P. , Mellor Phillip H. , Friswell Michael I. , Lieven Nick A.J.
Published: December 2006

Magnetic fiber reinforced composite material is being developed which utilizes hollow glass fibers filled with active ferromagnetic material. The resulting material maintains structural integrity as is, providing a possible means of electrical power generation from a dynamically loaded structure. The hollow glass fibers are manufactured in-house using a bespoke fiber drawing facility. Hard magnetic powder materials are introduced into the hollow fiber cores to provide an active ferromagnetic function. The first part of this article discusses the ongoing work to manufacture, characterize, and optimize active magnetic fiber reinforced composite materials.

Recent advances in smart material actuators have led to the development of piezoceramic `patches' that utilize the piezoelectric effect of individual fibers encased in a protective environment. Previously, these patches have been either positioned on the surface or embedded within the structure, disrupting the composite lay-up. The second part of the article outlines a study of the feasibility of embedding piezoelectric fibers directly into a composite lay-up, thereby allowing a composite laminate to deform due to internal actuation. Potential improvements to the work have been identified and future work has been proposed to further understand and maximize the performance of integrated piezoelectric fiber composites.
Accurate Modeling of the Electric Field within Piezoelectric Layers for Active Composite Structures
Authors: Marinković Dragan , Köppe Heinz , Gabbert Ulrich
Published: December 2006

The article considers thin-walled active structures, which utilize the piezoelectric patches as both sensor and actuator components. Most of the developed models for this type of application make an assumption of a constant electric field and, consequently, a linear distribution of the electric potential over the thickness of the piezopatches. Some recent papers use higher-order functions to model the mentioned electric quantities. In the study, it is demonstrated through an analytical deduction that a quadratic distribution of the electric potential and a linear distribution of the electric field are adequate for the piezoelectric patch that exhibits kinematics described by a first-order two-dimensional theory. A degenerated shell element is developed for modeling purposes and a set of numerical analyses is performed in order to demonstrate the additional stiffening effect caused by the refined functions for the electric quantities. The significance of the effect is discussed in detail.
Nonmalignant T cells stimulate growth of T-cell lymphoma cells in the presence of bacterial toxins
Authors: Woetmann Anders , Lovato Paola , Eriksen Karsten W. , Krejsgaard Thorbjørn , Labuda Tord , Zhang Qian , Mathiesen Anne-Merethe , Geisler Carsten , Svejgaard Arne , Wasik Mariusz A. , Ødum Niels
Published: December 2006

Bacterial toxins including staphylococcal enterotoxins (SEs) have been implicated in the pathogenesis of cutaneous T-cell lymphomas (CTCLs). Here, we investigate SE-mediated interactions between nonmalignant T cells and malignant T-cell lines established from skin and blood of CTCL patients. The malignant CTCL cells express MHC class II molecules that are high-affinity receptors for SE. Although treatment with SE has no direct effect on the growth of the malignant CTCL cells, the SE-treated CTCL cells induce vigorous proliferation of the SE-responsive nonmalignant T cells. In turn, the nonmalignant T cells enhance proliferation of the malignant cells in an SE- and MHC class II–dependent manner. Furthermore, SE and, in addition, alloantigen presentation by malignant CTCL cells to irradiated nonmalignant CD4+ T-cell lines also enhance proliferation of the malignant cells. The growth-promoting effect depends on direct cell-cell contact and soluble factors such as interleukin-2. In conclusion, we demonstrate that SE triggers a bidirectional cross talk between nonmalignant T cells and malignant CTCL cells that promotes growth of the malignant cells. This represents a novel mechanism by which infections with SE-producing bacteria may contribute to pathogenesis of CTCL.
Reduction of GVHD and enhanced antitumor effects after adoptive infusion of alloreactive Ly49-mismatched NK cells from MHC-matched donors
Authors: Lundqvist Andreas , Philip McCoy J. , Samsel Leigh , Childs Richard
Published: December 2006

We investigated if an infusion of alloreactive natural killer (NK) cells would reduce GVHD and mediate antitumor effects in mice undergoing MHC-matched allogeneic stem cell transplantation (SCT). Balb/c mice bearing RENCA tumors underwent an allogeneic SCT from MHC-matched B10.d2 donors and were given a single infusion of either Ly49 ligand-matched, ligand-mismatched, or no donor NK cells. Recipients of Ly49 ligand-mismatched NK cells had a reduced incidence of graft-versus-host disease (GVHD; 39% vs 100%; P < .01), and prolonged survival (median 84 days vs 39 days; P < .01) compared with SCT recipients not receiving NK cells. Recipients of Ly49 ligand-matched NK cells had the same incidence of GVHD and similar survival compared with controls not receiving NK cells. Pulmonary tumor burden was significantly (P < .01) lower in recipients that received Ly49-mismatched or Ly49-matched NK cells compared with recipients not receiving NK cells. These data provide in vivo evidence that a single infusion of alloreactive donor NK cells reduces GVHD and mediates antitumor effects following MHC-matched allogeneic transplantation.
A novel PAX5-ELN fusion protein identified in B-cell acute lymphoblastic leukemia acts as a dominant negative on wild-type PAX5
Authors: Bousquet Marina , Broccardo Cyril , Quelen Cathy , Meggetto Fabienne , Kuhlein Emilienne , Delsol Georges , Dastugue Nicole , Brousset Pierre
Published: December 2006

We report a novel t(7;9)(q11;p13) translocation in 2 patients with B-cell acute lymphoblastic leukemia (B-ALL). By fluorescent in situ hybridization and 3′ rapid amplification of cDNA ends, we showed that the paired box domain of PAX5 was fused with the elastin (ELN) gene. After cloning the full-length cDNA of the chimeric gene, confocal microscopy of transfected NIH3T3 cells and Burkitt lymphoma cells (DG75) demonstrated that PAX5-ELN was localized in the nucleus. Chromatin immunoprecipitation clearly indicated that PAX5-ELN retained the capability to bind CD19 and BLK promoter sequences. To analyze the functions of the chimeric protein, HeLa cells were cotransfected with a luc-CD19 construct, pcDNA3-PAX5, and with increasing amounts of pcDNA3-PAX5-ELN. Thus, in vitro, PAX5-ELN was able to block CD19 transcription. Furthermore, real-time quantitative polymerase chain reaction (RQ-PCR) experiments showed that PAX5-ELN was able to affect the transcription of endogenous PAX5 target genes. Since PAX5 is essential for B-cell differentiation, this translocation may account for the blockage of leukemic cells at the pre–B-cell stage. The mechanism involved in this process appears to be, at least in part, through a dominant-negative effect of PAX5-ELN on the wild-type PAX5 in a setting ofPAX5 haploinsufficiency.
Expression and release of soluble HLA-E is an immunoregulatory feature of endothelial cell activation
Authors: Coupel Stéphanie , Moreau Anne , Hamidou Mohamed , Horejsi Vaclav , Soulillou Jean-Paul , Charreau Béatrice
Published: December 2006

Human leukocyte antigen (HLA)–E belongs, with HLA-G and HLA-F, to the nonclassic major histocompatibility complex (MHC) class I (Ib) molecules, broadly defined by a limited polymorphism and a restricted pattern of cellular expression. In contrast to HLA-G, the expression and function of HLA-E and HLA-F in physiologic and pathologic processes remain poorly established. In the present study, we show that HLA-E protein expression in normal human nonlymphoid organs is mainly restricted to endothelial cells (ECs). HLA-E is also basally expressed by B and T lymphocytes, natural killer (NK) cells and by macrophages. We demonstrate that tumor necrosis factor α (TNFα), interleukin-1β (IL-1β), and interferon γ (IFNγ) up-regulate the cell-surface expression of HLA-E on ECs in vitro and induce the release of soluble HLA-E (sHLA-E). HLA-E up-regulation protects IFNγ-activated ECs from NK-mediated cell lysis, while sHLA-E protects bystander cells. Finally, sHLA-E is not detected in normal sera, and increased serum levels correlate with disease activity in patients with antineutrophil cytoplasmic antibody–associated systemic vasculitis. Thus, HLA-E expression and release of sHLA-E are features of EC activation and emphasize immunoregulatory functions of the endothelium. The present identification of soluble HLA-E molecules may have important implications in understanding the pathogenesis of immune-mediated vascular diseases and for the diagnosis and monitoring of patients.
Rapamycin derivatives reduce mTORC2 signaling and inhibit AKT activation in AML
Authors: Zeng Zhihong , Sarbassov Dos D. , Samudio Ismael J. , Yee Karen W. L. , Munsell Mark F. , Ellen Jackson C. , Giles Francis J. , Sabatini David M. , Andreeff Michael , Konopleva Marina
Published: December 2006

The mTOR complex 2 (mTORC2) containing mTOR and rictor is thought to be rapamycin insensitive and was recently shown to regulate the prosurvival kinase AKT by phosphorylation on Ser473. We investigated the molecular effects of mTOR inhibition by the rapamycin derivatives (RDs) temsirolimus (CCI-779) and everolimus (RAD001) in acute myeloid leukemia (AML) cells. Unexpectedly, RDs not only inhibited the mTOR complex 1 (mTORC1) containing mTOR and raptor with decreased p70S6K, 4EPB1 phosphorylation, and GLUT1 mRNA, but also blocked AKT activation via inhibition of mTORC2 formation. This resulted in suppression of phosphorylation of the direct AKT substrate FKHR and decreased transcription of D-cyclins in AML cells. Similar observations were made in samples from patients with hematologic malignancies who received RDs in clinical studies. Our study provides the first evidence that rapamycin derivatives inhibit AKT signaling in primary AML cells both in vitro and in vivo, and supports the therapeutic potential of mTOR inhibition strategies in leukemias.
Overexpression of nucleolin in chronic lymphocytic leukemia cells induces stabilization of bcl2 mRNA
Authors: Otake Yoko , Soundararajan Sridharan , Sengupta Tapas K. , Kio Ebenezer A. , Smith James C. , Pineda-Roman Mauricio , Stuart Robert K. , Spicer Eleanor K. , Fernandes Daniel J.
Published: December 2006

B-cell chronic lymphocytic leukemia (CLL) is characterized by the accumulation of clonal B cells that are resistant to apoptosis as a result of bcl2 oncogene overexpression. Studies were done to determine the mechanism for the up-regulation of bcl-2 protein observed in CD19+ CLL cells compared with CD19+ B cells from healthy volunteers. The 11-fold higher level of bcl-2 protein in CLL cells was positively correlated with a 26-fold elevation in the cytosolic level of nucleolin, a bcl2 mRNA–stabilizing protein. Measurements of the bcl2 heterogeneous nuclear/bcl2 mRNA (hnRNA)/mRNA ratios and the rates of bcl2 mRNA decay in cell extracts indicated that the 3-fold higher steady-state level of bcl2 mRNA in CLL cells was the result of increased bcl2 mRNA stability. Nucleolin was present throughout the nucleus and cytoplasm of CLL cells, whereas in normal B cells nucleolin was only detected in the nucleus. The addition of recombinant human nucleolin to extracts of normal B cells markedly slowed the rate of bcl2 mRNA decay. SiRNA knockdown of nucleolin in MCF-7 cells resulted in decreased levels of bcl2 mRNA and protein but no change in β-actin. These results indicate that bcl-2 overexpression in CLL cells is related to stabilization of bcl2 mRNA by nucleolin.
Members of the glutathione and ABC-transporter families are associated with clinical outcome in patients with diffuse large B-cell lymphoma
Authors: Andreadis Charalambos , Gimotty Phyllis A. , Wahl Peter , Hammond Rachel , Houldsworth Jane , Schuster Stephen J. , Rebbeck Timothy R.
Published: December 2006

Standard chemotherapy fails in 40% to 50% of patients with diffuse large B-cell lymphoma (DLBCL). Some of these failures can be salvaged with high-dose regimens, suggesting a role for drug resistance in this disease. We examined the expression of genes in the glutathione (GSH) and ATP-dependent transporter (ABC) families in 2 independent tissue-based expression microarray datasets obtained prior to therapy from patients with DLBCL. Among genes in the GSH family, glutathione peroxidase 1 (GPX1) had the most significant adverse effect on disease-specific overall survival (dOS) in the primary dataset (n = 130) (HR: 1.68; 95% CI: 1.26-2.22; P < .001). This effect remained statistically significant after controlling for biologic signature, LLMPP cell-of-origin signature, and IPI score, and was confirmed in the validation dataset (n = 39) (HR: 1.7; 95% CI: 1.05-2.8; P = .033). Recursive partitioning identified a group of patients with low-level expression of GPX1 and multidrug resistance 1 (MDR1; ABCB1) without early treatment failures and with superior dOS (P < .001). Overall, our findings suggest an important association of oxidative-stress defense and drug elimination with treatment failure in DLBCL and identify GPX1 and ABCB1 as potentially powerful biomarkers of early failure and disease-specific survival.
Functional status decline as a measure of adverse events in home health care: an observational study
Authors: Scharpf Tanya Pollack , Colabianchi Natalie , Madigan Elizabeth A , Neuhauser Duncan , Peng Timothy , Feldman Penny H , Bridges John FP
Published: December 2006

Background

Research that examines the quality of home health care is complex because no gold standard exists for measuring adverse outcomes, and because the patient and clinician populations are highly heterogeneous. The objectives in this study are to develop models to predict functional decline for three indices of functional status as measures of adverse events in home health care and determine which index is most appropriate for risk-adjusting for future quality research.

Methods

Data come from the Outcomes and Assessment Information Set (OASIS) from a large urban home health care agency and other agency data. Prognostic data yields 49,437 episodes, while follow-up data yields 47,684 episodes. We tested three indices defined as substantial decline in three or more (gt3_ADLs), two or more (gt2_ADLs), and one or more (gt1_ADLs) ADLs. Multivariate logistic regression determines the performance of the models for each index as measured by the c-statistic and Hosmer-Lemeshow chi square (χ2).

Results

Frequencies for gt3_ADLs, gt2_ADLs, and gt1_ADLs are 212 (0.43%), 783 (1.58%), and 4,271 (8.64%) respectively. Follow-up results are comparable with frequencies of 218 (0.46%), 763 (1.60%), and 3,949 (8.28%) for each index. Gt3_ADLs does not produce valid models. The model for gt2_ADLs consistently yields a higher c-statistic compared to gt1_ADLs (0.754 vs. 0.679, respectively). Both indices' models yield non-significant Hosmer-Lemeshow chi square indicating reasonable model fit. Findings for gt2_ADLs and gt1_ADLs are consistent over time as indicated by follow-up data results.

Conclusion

Gt2_ADLs yields the best models as indicated by a high c-statistic and a non-significant Hosmer-Lemeshow χ2, both of which exhibit exceptional consistency. We conclude that gt2_ADLs may be preferable in defining ADL adverse events in the context of home health care.