The major purposes of the presents study were (a) to examine the degree to which academic engagement mediates the relationship between parenting style and academic achievement. Data from 382 participants (191 males and 191 females) were examined using measures of parenting style, academic engagement, and self-reported grade point average. The results indicated that academic engagement mediate relationship between parenting style an academic achievement. Implications for future research are discussed. [Elham Dehyadegary, Kouros Divsalar, Nooshin Sabour Esmaeili, Azimeh Jafari Sadr, Fatemeh Askari. Academic Engagement as a Mediator in Relationship between Parenting Style and Academic Achievement among Adolescents in Sirjan-Iran. Life Sci J 2012;9(4):5715-5727] (ISSN:1097-8135). http://www.lifesciencesite.com. 851

When assessing the mechanical durability of electronic assemblies, the focus is generally on the solder interconnect. However, in many package styles, such as BGAs (ball grid arrays), LGAs (land grid arrays), MLFs (micro lead frame) and QFNs (quad flat no-lead), the Cu trace emanating from the solder pad may be the weakest failure site, especially if the solder joint is copper-defined rather than mask-defined. This is particularly true in situations with cyclic mechanical loading, such as cyclic quasi-static bending, vibration and repetitive drop/shock. This study focuses on quasi-static mechanical cycling durability of LGA assemblies with copper-defined pads. Specimens were cycled to failure under zero-to-max, three-point bending and failure statistics were collected. The failure mode was confirmed to be fatigue cracks in copper traces emanating from the corner solder pads, just at the edge of the solder mask where the solder joint ends. The cracks were identified by lateral polishing after desoldering the component. The cyclic bending of this assembly was modeled with 3D, elastic-plastic, large deformation finite element analysis. Due to the complexity of the geometry, a global-local approach was used to identify the strain history and the mean-stress at the failure site. A generalized strain-based fatigue model was used to characterize these failures, and preliminary model constants were iteratively estimated by ensuring that they were simultaneously compatible with both the durability test data and the copper stress-strain curves used in the FEA (finite element analysis). These preliminary model constants were then refined by separately modeling the initiation and progression history of fatigue damage in the cyclic bend tests. Damage progression was modeled in this study by using a technique of 'successive initiation' developed earlier by this research group. In this method, finite element simulations are used to progressively 'kill' elements that have accum- ulated sufficient fatigue damage to lose their load-carrying capacity. When the killed elements span the entire cross-section of the copper trace, the trace is assumed to electrically fail. This calibrated model is then used to demonstrate its ability to predict copper trace failures in other situations such as quasi-static 4-point bending of LGA assemblies and vibration of BGA assemblies. More important, we demonstrate its use for re-designing of BGA assemblies to prevent copper trace failures under drop/shock loading. The important impact of this study includes insight into copper trace failures in PWAs under mechanical cycling, a quantitative model to predict its occurrence, and validated guidelines to prevent it by design.

In this investigation, a dynamic simulation and optimization for an auto-thermal dual-type methanol synthesis reactor was developed in the presence of catalyst deactivation. Theoretical investigation was performed in order to evaluate the performance, optimal operating conditions, and enhancement of methanol production in an auto-thermal dual-type methanol reactor. The proposed reactor model was used to simulate, optimize, and compare the performance of a dual-type methanol reactor with a conventional methanol reactor. An auto-thermal dual-type methanol reactor is a shell-and-tube heat exchanger reactor in which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. The proposed model was validated against daily process data measured of a methanol plant recorded for a period of 4 years. Good agreement was achieved. The optimization was achieve by use of genetic algorithms in two steps and the results show there is a favorable profile of methanol production rate along the dual-type reactor relative to the conventional-type reactor. Initially, the optimal ratio of reactor lengths and temperature profiles along the reactor were obtained. Then, the approach was followed to get an optimal temperature profile at three periods of operation to maximize production rate. These optimization approaches increased by 4.7 % and 5.8 % additional yield, respectively, throughout 4 years, as catalyst lifetime. Therefore, the performance of the methanol reactor system improves using optimized dual-type methanol reactor.

We examine the spatial variability of the wind/roughness fields over the Adriatic Sea during BORA/SIROCCO wind events using RADARSAT synthetic aperture radar (SAR) imagery, QUICKSCAT scatterometer wind measurements, and simulations derived from high-resolution atmospheric Limited Area Model Italy (LAMI) and Coupled Ocean/Atmospheric Mesoscale Prediction System (COAMPS). BORA winds are manifested in SAR imagery as jet-like structures exhibiting intense roughness modulations along the eastern coast. SIROCCO winds produce more uniform roughness signatures and extend over the southern Adriatic. On the basis of comparisons with the SAR imagery, the atmospheric models are able to replicate the gross morphological structures of the wind field. However, higher resolution models are required for simulating more local orographic effects.

Airborne microwave radar imagery and coincident in situ data collected off Cape Hatteras, NC (USA) are used to examine the small-scale horizontal structure of a frontal region, which formed through intrusion of relatively dense Gulf Stream water onto the continental shelf. The frontal outcrop is shown to have a kilometer-wavelength scalloped structure consisting of sharp angular features (cusps) alternating with broad, gently curved regions (troughs). There is also an associated pattern of slicks lying on the buoyant side of the front and asymmetrically offset from the cusps. These slicks appear to originate from biophysical processes associated with the front itself and to trace out cyclonic trajectories of surface fluid particles. It is conjectured that the distinctive horizontal pattern of frontal cusps and slicks arises from shear-flow instability modified by the requirement for convergence of buoyant water along the front.

We identify upwelling signatures caused by eddy interactions with bottom topography on the downstream of the Malta Plateau, using space-borne remote sensing Advanced Very High Resolution Radiometer (AVHRR) imagery, ERS-1 Synthetic Aperture Radar (SAR) imagery, Topex/Poseidon/ERS-2 (TPE) altimeter maps, and Orbview2/SeaWiFS imagery. The cyclonically rotating eddy contributes to upwelling, reducing the sea surface temperature (SST) by about 1-2°C inside the eddy with respect to the ambient ocean. Ocean colour imagery shows increases in pigment concentrations (0.5 mg m-3) associated with the eddy. In TPE altimeter maps, the eddy is manifested as a 40-50 km wide 'bowl-shaped' structure, with negative sea height anomalies ranging between 6 and 10 cm. The eddy-type motion is further evidenced in SAR imagery by the appearance of striations forming along the boundaries of the eddy as well as reduced backscatter at its centre. The study demonstrates the utility of sensor fusion and identifies a set of generic indicators for upwelling identification and tracking using multiple sensors.

The authors use simulations of radar cross-section, based on wave-current interaction calculations, to investigate the origin of a prominent enhancement in L-band, HV polarization radar return that was observed in imagery of the northern boundary of the Gulf Stream (GS) during the first Shuttle Radar Laboratory (SRL-1) mission. The calculations of surface roughness are based on a 1-dimensional surface current model that closely resembles a current convergence that was observed in in-situ current measurements, taken at both sides of the Stream at the time SRL-1 imaged the GS boundary. In agreement with trends observed in the imagery, significant enhancements in L-band HV polarization cross-section occur in the neighborhood of the GS boundary, relative to comparable VV polarization cross-section signatures at X-, C- and L-band. This occurs despite the fact that the magnitude of the L-band HV cross-section is significantly reduced relative to the comparable X-, C-, and L-band VV cross-sections. These results indicate that the associated L-band HV enhancement occurs from tilt-induced modulation in the radar backscatter, which preferentially alters the relative modulation in L-band HV backscatter in regions where considerable variation in surface slope takes place. The authors also provide an overview of a number of additional sub-mesoscale features associated with the Gulf Stream that were present in the image of the GS boundary

Bright linear features have been observed in radar imagery taken near the Gulf Stream (GS) boundary on two separate occasions. In each case, these have been observed directly over strong current convergences. Progress has been made in understanding the origin of these signatures through simulations that incorporate environmental forcing from the winds and currents. These simulations significantly underestimate the backscatter unless wave-breaking (WB) effects are included at least approximately. Using a new, quasistatistical procedure that generalizes and quantifies earlier procedures for including WB effects, the authors have been able to successfully simulate the magnitude and behavior of these signatures. The approach combines the statistically based, composite model of radar backscatter with a deterministic feature model that relates backscatter from breaking waves to a particular geometrical model of a spilling breaker. This is accomplished using localized criteria, defined by local wave crest acceleration, to determine the probability of breaking, and by extending the feature model so that its unknown parameters may be evaluated directly from wave-current interaction calculations. The new approach provides an estimate of the critical crest acceleration of a potentially breaking wave, as a function of wind speed, that agrees with independent measurements.

Field observations, including hydrographic, microwave imaging radar, and HF radar measurements, reveal the evolution of a complicated frontal interaction between three water masses on the continental shelf near Cape Hatteras, North Carolina, during a period of incursion of water from the Gulf Stream. The water masses were found to be separated by intersecting frontal lines configured in a manner analogous to an occluded atmospheric front. The densest water lay between inshore and offshore fronts that gradually merged or occluded in the generally downstream direction, leaving a single surface front. The overall frontal structure appeared as a distinct Y-shaped feature in the radar imagery, similar to historical imagery of the study area. The interpretation of the observations is aided by the use of a two-dimensional numerical model. The model is initialized with two fronts idealized from the ocean measurements. The model fronts quickly sharpen and begin to move together, eventually occluding into a single surface front. As a result of the occlusion, the water mass having intermediate density subducts and intrudes under the most buoyant water, carrying with it strong horizontal and vertical shears, and a frontal band of diverging currents is created in the densest water mass. The model thus suggests that in the ocean there will be an increase in hydrographic and velocity fine structure downstream of the frontal occlusion point.

Imaging radars, under certain environmental conditions, can provide an extensive description of shallow submarine topography. In this investigation, sand waves were observed in shallow water and under light winds, weak flow, and highly stratified conditions with an L band synthetic aperture radar and X band real aperture radar. An analysis of the radar data reveals that regularly spaced modulations seen in the imagery are a result of bathymetric forcing. These modulations appear as a group of bright linear east-west trending features approximately 5 km in length and spaced 230 m apart with observed peak modulations exceeding predicted modulations by 7 dB. Bathymetric measurements extracted from shipboard ADCP data confirm the existence of sand waves in this region. Results from the ADCP data reveal an east-west orientation of the sand wave crest with lee slopes facing north. Mean wavelengths are 230 m and the heights are roughly 2.5 m. The radar modulations lead the sand wave crest, by approximately 135 m suggesting a possible upstream hydrodynamic effect, which is consistent with an observed Froude number less than one. This study shows that bathymetric effects are observed in radar imagery at low current speed, light winds, and strong stratification, demonstrating the critical nature that topographic and stratified hydrodynamic effects have on radar image interpretation in the littoral environment.

This paper describes a PC-based multilayered data integration and classification system that is under development for monitoring coastal oceanographic processes. For data integration and sensor fusion, the authors have developed a multilayered “hypercube” that includes data from satellite ERS-1, multi-frequency airborne SAR imagery, AVHRR imagery, in situ measurements of temperature, salinity and the calculated sound speed. The authors show examples from a number of the systems applications that include: georeferencing, sensor fusion, pattern classification and automatic frontal detection, geophysical parameter extraction, objective interpolation, and prediction of acoustic propagation loss within the water column

We examine the radar signatures and changes in the surface roughness associated with oceanic features in the low grazing angle (LGA) scattering regime. The X band (HH) radar signatures consist of high-amplitude sea spikes, step changes in the normalized radar cross-section (NRCS) modulations, and bright narrowbanded frontal structures. Using in situ observations coupled with airborne precision radiation thermometer (PRT-5) data, we show that the step changes in radar cross-section modulations are associated with either thermal stability-induced stress variations or current velocity variations. Superimposed on the step changes are additional modulations that result from wave breaking and hydrodynamic straining. The amplitudes of the NRCS LGA measurements are compared with the predictions of four backscattering models: the Bragg, the tilted-Bragg, the wedge, and the plume model. It is shown that while the simple Bragg model can describe the measurements to a limited degree, it generally tends to underpredict the results. Agreement is improved by including the tilt contribution from the longwave surface waves in the context of the composite scattering model. We use the wedge and plume models as the basis for explaining the cross sections associated with the high-amplitude sea spikes. The wedge model is used to describe scattering from sharply crested waves, and the plume model is used to describe the extreme cross sections that are associated with breaking waves near the fronts. In describing the probability density function characteristics we show that the backscattering statistics exhibit “K distribution” behavior for the Gulf Stream current region and near-frontal regions, while the cooler shelf waters have characteristics of an exponential distribution.

Crigler-Najjar syndrome type I (CN-I) is a congenital hepatic metabolic deficiency in bilirubin UDP-glucuronosyltransferase activity which leads to profound jaundice and death from kernicterus. UGT1, the gene locus coding for multiple glucuronosyltransferase isoforms, has been well characterized and the cDNA for the most active form, HUG Br1, has been cloned. Recent advances in liver directed gene transfer suggest that this disease could be treated through gene therapy. As an initial step to correct the genetic defect in Crigler-Najjar type I, recombinant retroviruses were used to transduce an HUG Br1 gene into hepatocytes of a rat model of CN-I and CN-I fibroblasts. The retroviral vector gagCMVBA HUG Br1 was constructed and helper-free amphotrophic virus was isolated and used to transfer bilirubin UDP-glucuronosyltransferase activity to genetically deficient cells. The efficiency of transduction as measured by Southern blot analysis of integrated proviral sequences in DNA of recipient cells ranged from 5 to 100%. HUG Br1 gene expression was documented by blot hybridization analysis of total cellular RNA, immunotransblot analysis using a rabbit polyclonal antipeptide HUG Br1 antibody, and lysate enzymatic assay of bilirubin UDP-glucuronosyltransferase activity. HUG Br1 gene transfer was definitively demonstrated by four independent modalities following HUG Br1 retroviral transduction.

This article investigates the scatterometer radar cross-section distributions and wind stress spatial variability across a sea surface temperature (SST) front under different wind directions and synoptic scale atmospheric forcings. Shipboard meteorological measurements in concert with airborne Ku-band (14.0 Ghz) rotating scatterometer data show evidence of mesoscale circulation near the front during low ambient winds (4 m/s) blowing from the cold side of the SST front to the warm side. The mesoscale signature is characterized by a 25–35° counterclockwise shift in the wind direction and a maximum of 4.9 dB increase in the backscattering cross section across the front. The mesoscale circulation is reduced when the wind direction reverses, and the ambient wind flow increases to 13.6 m/s. The maximum cross-section change across the front is reduced to 3.6 dB. The azimuthal characteristics of the scatterometer data are compared with the predictions of two scatterometer model functions. According to the models, the anisotropy of the short waves is inversely related to the wind speed, such that the short wave directional spreads tend to broaden as the wind speed increases. The scatterometer data, however, show greater short-wave anisotropy at the higher wind speeds. This measured difference could be caused by current velocity changes or by longwave directional changes across the front.

The Shuttle Imaging Radar, (SIR)-C/X-SAR, first and second Shuttle Radar Laboratory (SRL) missions, SRL-1 and SRL-2, took place April 9-20 and Sept. 30-Oct. 10, 1994. The authors report on a major, multi organizational series of experiments designed to investigate oceanographic phenomena at the Gulf Stream (GS) Supersite off the east coast of the US during these two missions. The investigations emphasized current-wave and air-sea interactions with extensive ground/sea/air truthing. The authors summarize a number of detailed findings associated with SRL-1 and provide a preliminary description of SRL-2 results.

Laboratory experiments are conducted in a wind-wave tank facility to investigate the physics of radar scattering associated with: (1) transient wave packets undergoing various stages of breaking, (2) the effects of propagation of solitons through a pre-existing wind wave sea. The problem is fundamental to the understanding of radar signatures of internal waves, ship wakes and deep water breaking waves. Using a programmable paddle which controls the steepness parameters of the wave-breaking process, five classes of waves with different steepness characteristics are considered including a symmetrical round wave, an asymmetrical steep wave, an incipient breaker, a spilling breaker, and a plunging breaker. Video imaging and resistance wire wave gauges are used to measure the surface displacement and the temporal evolution of the surface. Wave gauges spaced approximately 1.2 m apart are placed along the tank measuring the surface wave height, celerity, and curvature. Each wave gauge corresponds to a specific range bin in the radar's field of view. The radar is a pulsed Doppler dual polarized X-band (9.4 GHz) system with a 3 (ns) pulse width, and the antenna is centered at 80 degrees incidence. Observations are made with the wave packets propagating towards and away from the radar. The backscatter response from the breaking waves exhibit nonlinear behavior such that the magnitude of the return increases with the increase in front face slope and with the onset of breaking, but decreases when the intensity of wave breaking is more vigorous and of plunging type. The differences in modulations for upwave and downwave look directions are examined. For the experiments involving the propagation of solitons through a pre-existing wind wave sea, the wind speeds in the tank are varied between 5-15 ms/sup -1/. Based on the range gated radar time series, the temporal evolution of the surface is characterized into four separate stages. The radar signatures show strong polarization dependence both in the cross-section modulations and Doppler bandwidth characteristics, with stronger modulations in the HH scatter, and upshifts in the Doppler centroids of the HH return with respect to the VV return.< >

This article is devoted to the synthesis, characterization, and modification of acrylic-based superabsorbents which are synthesized by carrying out the well-known process of inverse suspension polymerization. The dispersion is stabilized by using a mixture of micromolecular and macromolecular stabilizers. High swelling and appropriate absorption kinetics are obtained, provided that parameters (including initial monomer and crosslinker concentration, range of neutralization degree, initiating and stabilizing system, monomer addition rate, temperature and nature of the organic phase) are being considered. Modifications of cross-linker and comonomer nature and their effects on absorbency characteristics (capacity and rate) of the above-mentioned superabsorbents are graphically presented. Finally, diffusion behavior of superabsorbents is briefly discussed. (C) 1994 John Wiley & Sons, Inc.

This paper investigates the radar imaging of ocean waves under two separate wind speed and sea state conditions using an X band real aperture radar (RAR). It is shown experimentally that for the case of higher sea state and wind speed (9.1 m/s), the RAR is capable of imaging the waves from all directions including the azimuth. The case for low sea state and wind speed (4.5 m/s), however, shows somewhat stronger imaging contrast in the range direction with reduced contrast for the azimuth‐traveling waves. The results of the aircraft observations are compared with numerical simulations of a RAR imaging model. Simulations show that cross tilt is a viable mechanism for enhancing the azimuthal modulations, but the results are sensitive to the level of upwind/cross‐wind anisotropy of the shortwave spectrum. Simulations also show that the variations in incidence angle create irregularities in the azimuthal angle distribution.

During the NRL Hi Res experiment (Mied et al., 1992), several regions of anomalously high radar backscatter were observed. These “rip” features have been modeled as current convergence regions, based on ship-borne current measurements. Ship mounted optical data have been analyzed to produce slope statistics in one and two dimensions (Raiser and Lindemann, 1992). These measurements show that in the region of the rip, the measured slopes exhibit an isotropic spatial distribution that is absent in other regions. Slope spectral measurements during a transit of the rip were constructed from ship based optical data using a modified Stilwell technique. The authors have calculated the slope spectra using the wave action equation in the ERIM Ocean Model (Lyzenga and Bennett, 1988). They present a preliminary comparison between the data and the model results