bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessing Educational Effectiveness: Policy Implications from Diverse Areas of Research*
Authors: Marsh Herbert W. , Nagengast Benjamin , Fletcher John , Televantou Ioulia 
Published: August 2011

AbstractIn England, school league tables – based on student scores on standardised tests – are used extensively by policymakers and parents as one of the key measures of secondary school effectiveness. Here, we briefly review the English contextual value added (E‐CVA) model used to construct league tables of school effectiveness and juxtapose it with studies that focus on teacher effectiveness, other criteria of educational effectiveness and effectiveness at the university level. Methodologically, we consider the fragility of causal inferences based on psychometric and econometric value added models, and new multilevel models that take into account measurement and sampling error. Value added models largely ignore measurement error which systematically biases the outcomes, but both measurement and sampling error can be incorporated into doubly‐latent models that integrate multilevel and latent variable approaches. The E‐CVA model focuses on school effects and ignores teacher effects. However, research on both secondary schools and universities shows that there is little variance at the school or university level, but much more at the teacher level. E‐CVA models consider test scores as the only indicator of effectiveness; there is little emphasis on other indicators of effectiveness, tests of the construct validity of test scores as a measure of effectiveness in relation to other indicators, or formative evaluations to improve effectiveness. Research on university students' ratings of teachers incorporates a broader perspective to construct validation: multidimensional factor structure, reliability/stability, relations with multiple criteria of effective teaching, and interventions to improve teaching. Both areas of research could learn from the other, and many strategies from the higher‐education literature could be incorporated into the literature on educational effectiveness at the primary‐ and secondary‐school levels.
Recent Developments in the Identification and Estimation of Production Functions of Skills*
Authors: Cunha Flávio 
Published: August 2011

AbstractThis paper summarises the literature on the estimation of production functions governing the process of skill formation. This literature focuses on attacking three problems. The first is the endogeneity of measures of investments. The second is the measurement error in skills and investments that are widely used in the literature. Endogeneity and measurement error produce, in general, inconsistent estimates. The third problem is the lack of a metric for tests designed to measure skills. The fact that scores have no cardinal meaning implies that the coefficients of the production function have no economic meaning. We show that anchoring test scores on outcomes that have a natural metric produces estimates that are economically interpretable.
Previous overt hepatic encephalopathy rather than minimal hepatic encephalopathy impairs health‐related quality of life in cirrhotic patients
Authors: Moscucci Federica , Nardelli Silvia , Pentassuglio Ilaria , Pasquale Chiara , Ridola Lorenzo , Merli Manuela , Riggio Oliviero 
Published: August 2011

AbstractBackgroundIt has been observed that overt hepatic encephalopathy (HE) is accompanied by a persistent cognitive defect, suggesting that HE may not be fully reversible. The health‐related quality‐of‐life (HRQoL) has been shown to be impaired by cirrhosis, and, according to some reports, influenced by minimal HE. Little is known about the effect of previous HE on HRQoL.AimTo investigate the relative impact of previous HE and minimal HE on HRQoL in a group of consecutively hospitalized cirrhotic patients.Patients/MethodsSeventy five consecutive cirrhotic patients were evaluated using the Psychometric HE Score (PHES) and simplified Psychometric HE Score (SPHES) to detect the presence of minimal HE and using SF‐36 to assess the HRQoL, both corrected for age and education. Eighteen of them had previous bouts of overt HE.ResultsMinimal HE was significantly more frequent in patients with previous HE than in those without (p < 0.001), independently on the method used for the diagnosis (PHES or SPHES). A deeper impairment in several domains of SF‐36 was observed in patients with previous bouts of overt HE, in those with ascites, as well as in those with decompensated cirrhosis. At multivariate analysis, ascites, MELD score and previous HE were independently related to the mental‐component‐summary (MCS) of SF‐36, whereas ascites was the only variable independently associated with the physical‐component‐summary (PCS) of SF‐36. Minimal HE (independently on the method used for its diagnosis) impaired only one domain of SF‐36.ConclusionsThese data suggest that previous bouts of HE, despite their complete clinical resolution, play an independent role in producing a persistent impairment in HRQoL of cirrhotics.
A Method for Control of an Implantable Rotary Blood Pump for Heart Failure Patients Using Noninvasive Measurements
Authors: Lim Einly , Alomari Abdul‐Hakeem H. , Savkin Andrey V. , Dokos Socrates , Fraser John F. , Timms Daniel L. , Mason David G. , Lovell Nigel H. 
Published: August 2011

AbstractWe propose a deadbeat controller for the control of pulsatile pump flow (Qp) in an implantable rotary blood pump (IRBP). Noninvasive measurements of pump speed and current are used as inputs to a dynamical model of Qp estimation, previously developed and verified in our laboratory. The controller was tested using a lumped parameter model of the cardiovascular system (CVS), in combination with the stable dynamical models of Qp and differential pressure (head) estimation for the IRBP. The control algorithm was tested with both constant and sinusoidal reference Qp as input to the CVS model. Results showed that the controller was able to track the reference input with minimal error in the presence of model uncertainty. Furthermore, Qp was shown to settle to the desired reference value within a finite number of sampling periods. Our results also indicated that counterpulsation yields the minimum left ventricular stroke work, left ventricular end diastolic volume, and aortic pulse pressure, without significantly affecting mean cardiac output and aortic pressure.
Evaluation of Hydraulic Radial Forces on the Impeller by the Volute in a Centrifugal Rotary Blood Pump
Authors: Boehning Fiete , Timms Daniel L. , Amaral Felipe , Oliveira Leonardo , Graefe Roland , Hsu Po‐Lin , Schmitz‐Rode Thomas , Steinseifer Ulrich 
Published: August 2011

AbstractIn many state‐of‐the‐art rotary blood pumps for long‐term ventricular assistance, the impeller is suspended within the casing by magnetic or hydrodynamic means. For the design of such suspension systems, profound knowledge of the acting forces on the impeller is crucial. Hydrodynamic bearings running at low clearance gaps can yield increased blood damage and magnetic bearings counteracting high forces consume excessive power. Most current rotary blood pump devices with contactless bearings are centrifugal pumps that incorporate a radial diffuser volute where hydraulic forces on the impeller develop. The yielding radial forces are highly dependent on impeller design, operating point and volute design. There are three basic types of volute design—singular, circular, and double volute. In this study, the hydraulic radial forces on the impeller created by the volute in an investigational centrifugal blood pump are evaluated and discussed with regard to the choice of contactless suspension systems. Each volute type was tested experimentally in a centrifugal pump test setup at various rotational speeds and flow rates. For the pump's design point at 5 L/min and 2500 rpm, the single volute had the lowest radial force (∼0 N), the circular volute yielded the highest force (∼2 N), and the double volute possessed a force of approx. 0.5 N. Results of radial force magnitude and direction were obtained and compared with a previously performed computational fluid dynamics (CFD) study.
Alterations in Red Blood Cell Volume and Hemoglobin Concentration, Viscoelastic Properties, and Mechanical Fragility Caused by Continuous Flow Pumping in Calves
Authors: Yokoyama Naoyuki , Sakota Daisuke , Nagaoka Eiki , Takatani Setsuo 
Published: August 2011

AbstractIn this study, we have analyzed the changes in mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), and the dynamic deformability and mechanical fragility of red blood cells (RBCs) in five male Holstein calves (body weight: 95.6 ± 10.8 kg) whose circulation was partially supported with a novel magnetically levitated extracorporeal centrifugal blood pump MedTech Dispo. One hour after the pumping has started, the MCV increased and the MCHC decreased by 1.064 ± 0.006 and 0.906 ± 0.050 times, respectively, as compared with those of the prepumped blood (P < 0.05). The deformability index L/W, where L and W are the long and short axes of the two‐dimensional RBC images, respectively, sheared by a cyclically reversing shear flow increased indicating that the RBCs pumped for 1 h exhibited more elastic characteristics (P < 0.05). In addition, when the pumped blood cells were sheared for 30 min with a uniform shear stress of 25.38 Pa, the hemolysis level decreased dramatically as compared with the control blood, as more fragile RBCs were destroyed by pumping, leaving behind less fragile RBCs. All these characteristics of the RBCs exposed to continuous flow resemble those of young RBCs having larger MCV, lower MCHC, higher elasticity, and lower fragility. In conclusion, during continuous flow pumping, the RBCs having relatively lower threshold for hemolysis to mechanical shear stress generated by continuous flow blood pump (CFBP) are destroyed first and removed from circulation in the early stage of application of CFBP, thus leaving behind less fragile and stronger RBCs.
Results of Animal Experiments With the Fourth Model of the Undulation Pump Total Artificial Heart
Authors: Abe Yusuke , Isoyama Takashi , Saito Itsuro , Shi Wei , Inoue Yusuke , Ishii Kohei , Nakagawa Hidemoto , Ono Toshiya , Ono Minoru , Imachi Kou 
Published: August 2011

AbstractAnimal experiments using a total artificial heart in a goat are not easy to perform. The fourth model of the undulation pump total artificial heart (UPTAH4), which was designed to perform a long‐term physiological experiment including pulsatile and nonpulsatile TAH operations with a conductance‐ and arterial pressure‐based control method named 1/R control, was implanted in 31 goats weighing 38.5 to 60.4 kg (average of 46.8 kg). The 1/R control is a physiological flow control method of TAH developed with a conductance (1/R: reciprocal of a resistance) parallel circuit model. The survival periods were from 0.1 to 153 days (average of 14.5 days). The causes of termination were postoperative bleeding in eight goats, respiratory failure in five goats, device failure in 14 goats, dissected aneurysm in two goats, and thrombus in one goat. The thrombus case was the longest surviving goat. The respiratory failure tended to occur when the extracorporeal circulation time was prolonged. Autotransfusion was effective for the prolongation of survival time. The left–right balance control and the suction control were performed successfully in all goats. The 1/R control was performed for a long time in five goats that survived for more than 1 month. With three goats that survived for 48, 52, and 53 days mainly with the pulsatile mode, the 1/R control was stable. With a goat that survived for 73 days, the nonpulsatile mode with the 1/R control could be tested for 3 weeks. With the longest surviving goat that was maintained mainly with the pulsatile mode, the 1/R control was unstable, possibly due to the mismatching of the response time of the control system between the computer and the body. However, liver and kidney functions were almost normal, and the total protein level recovered. Further study to stabilize the 1/R control in the UPTAH is necessary.
One‐Month Biocompatibility Evaluation of the Pediatric TinyPump in Goats
Authors: Ando Yusuke , Kitao Takashi , Nagaoka Eiki , Kimura Taro , Yokoyama Yoshimasa , Yoshikawa Masaharu , Tominaga Ryuji , Takatani Setsuo 
Published: August 2011

AbstractThe TinyPump is an extracorporeal, magnetically driven centrifugal blood pump with its impeller suspended magnetically and hydrodynamically to provide short‐term mechanical circulatory support for children and infants. We have previously demonstrated that the in vivo experiments of the experimental TinyPump showed acceptable stable performance at pump flows averaging around 1.0 L/min with low hemolytic and thrombogenic properties for up to 2 weeks. We present here the 1‐month in vivo evaluation of the TinyPump, whose design was modified further for more durable operation. The pump was implanted as a left ventricular assist device in five goats (12.5–26.7 kg), with inflow inserted into the left ventricular apex and outflow anastomosed to the descending aorta. Five animals were supported for 110 pump days, with mean pump flow of 1.19 ± 0.03 L/min at a pump speed of 2679 ± 97 rpm. Two animals reached the scheduled end point of 30 days without device failure, and mean plasma‐free hemoglobin was 1.7 ± 0.8 mg/dL. Hematologic and biochemical data of these two animals showed no evidence of cardiovascular, renal, or hepatic dysfunction. Although further experiments are needed, the modified TinyPump offers promise as a short‐term mechanical circulatory support device in pediatric population.
Complications associated with implant migration into the maxillary sinus cavity
Authors: Galindo‐Moreno Pablo , Padial‐Molina Miguel , Avila Gustavo , Rios Hector F. , Hernández‐Cortés Pedro , Wang Hom‐Lay 
Published: August 2011

AbstractBackgroundMigration of dental implants into the maxillary sinus is an uncommon, but increasingly reported complication. Implant migration may result from initial lack of primary stability, intrasinusal and nasal pressure changes, autoimmune reaction to the implant or incorrect distribution of occlusal forces. This retrospective study aims at analyzing the factors that may influence implant migration into the maxillary sinus cavity.Material and methodsFourteen patients presenting a total 15 implants that migrated into the maxillary sinus were recruited. Diagnosis of this complication was based on imaging techniques, such as cone beam computerized tomography scan and panoramic radiography. Clinical data were recorded in all cases and processed for statistical analysis.ResultsABH was below 6 mm in the majority of cases. However, almost 50% of the patients did not receive any site preparation treatment prior to implant insertion. Five patients (33.3%) were treated by osteotome techniques, but only one of them had bone grafting. Therefore, 73.3% of sites did not receive any biomaterial to increase available bone height. The most common complication‐associated factors found on this study were related to implant design (cylindrical), implant dimension (diameter), implant restoration/rehabilitation method (partial removable denture), site‐specific anatomy (initial residual bone height between 5 and 6.9 mm), demographics (age), and biomaterials.ConclusionPatient selection and proper treatment planning, as well as the application of the appropriate sinus augmentation technique, are critical aspects that should be controlled to minimize the risk of implant migration into the maxillary sinus cavity. [Correction added after online publication August 17 2011: The Conclusion was revised to provide better clarity to the reader.]
Is oral health‐related quality of life stable following rehabilitation with mandibular two‐implant overdentures?
Authors: Jabbour Z. , Emami E. , de Grandmont P. , Rompré P. H. , Feine J. S. 
Published: August 2011

AbstractObjectivesThe superiority of mandibular two‐implant overdentures (IODs) over conventional complete dentures (CDs) in terms of quality of life is still questioned. Furthermore, the stability and magnitude of the treatment effect over time remain uncertain. This follow‐up study aimed to determine the stability and magnitude of the effect of IODs on oral health‐related quality of life (OHRQoL).Material and methods172 participants (mean age 71 ± 4.5 years) randomly received CDs or IODs, both opposed by conventional maxillary dentures. OHRQoL was measured using the Oral Health Impact Profile (OHIP‐20) at baseline, 1 and 2 years post‐treatment. Repeated measures ANOVAs were conducted to assess the effects of time and treatment on the total OHIP and its individual domain scores.ResultsA statistically significant improvement in OHRQoL was seen for both treatment groups (P < 0.001). This improvement was maintained over the 2 year assessment. At both follow‐ups, participants wearing IODs reported significantly better total OHIP scores than those wearing CDs (P < 0.001), with a 1.5 times larger magnitude of effect. In the CD group, baseline OHIP scores influenced the post‐treatment scores (P < 0.001). This effect was not found in the IOD group.ConclusionsThe effect of mandibular two‐IODs on OHRQoL is stable over a 2‐year period. The large magnitude of effect of this treatment supports its clinical significance.
Experimental
Determination of Spectral Transmittance of Porous Cerium Dioxide in the Range 900–1700
nm
Authors: Ganesan Krithiga , Lipiński Wojciech 
Published: August 2011

Abstract
Overall transmittance of porous cerium dioxide is measured in the spectral range of 900–1700 nm using dispersive spectroscopy. Dense and porous samples of cerium dioxide with average porosities of 0.08 and 0.72, respectively, are investigated. The transmittance of both sample types increases with decreasing thickness, and this trend is more pronounced for the dense samples. The on-average spectrally increasing transmittance of the dense samples is attributed to the decreasing absorption by bulk cerium dioxide with radiation wavelength. The transmittance of the porous samples, on the other hand, remains approximately constant over the spectrum. Porous samples attenuate radiation stronger than the dense samples at any wavelength in the considered range, and it is hypothesized that this effect is due to more intense scattering. Sharp local variations of the transmittance are observed for both sample types.
Measuring signal‐to‐noise ratio in partially parallel imaging MRI
Authors: Goerner Frank L. , Clarke Geoffrey D. 
Published: August 2011

Purpose:To assess five different methods of signal‐to‐noise ratio (SNR) measurement for partially parallel imaging (PPI) acquisitions.Methods:Measurements were performed on a spherical phantom and three volunteers using a multichannel head coil a clinical 3T MRI system to produce echo planar, fast spin echo, gradient echo, and balanced steady state free precession image acquisitions. Two different PPI acquisitions, generalized autocalibrating partially parallel acquisition algorithm and modified sensitivity encoding with acceleration factors (R) of 2–4, were evaluated and compared to nonaccelerated acquisitions. Five standard SNR measurement techniques were investigated and Bland–Altman analysis was used to determine agreement between the various SNR methods. The estimated g‐factor values, associated with each method of SNR calculation and PPI reconstruction method, were also subjected to assessments that considered the effects on SNR due to reconstruction method, phase encoding direction, and R‐value.Results:Only two SNR measurement methods produced g‐factors in agreement with theoretical expectations (g ≥ 1). Bland–Altman tests demonstrated that these two methods also gave the most similar results relative to the other three measurements.R‐value was the only factor of the three we considered that showed significant influence on SNR changes.Conclusions:Non‐signal methods used in SNR evaluation do not produce results consistent with expectations in the investigated PPI protocols. Two of the methods studied provided the most accurate and useful results. Of these two methods, it is recommended, when evaluating PPI protocols, the image subtraction method be used for SNR calculations due to its relative accuracy and ease of implementation.
The influence of field strength and different clinical breast MRI protocols on the outcome of texture analysis using foam phantoms
Authors: Waugh Shelley A. , Lerski Richard A. , Bidaut Luc , Thompson Alastair M. 
Published: August 2011

Purpose:Texture analysis (TA) has proved to be useful to distinguish different tissues and disease states using magnetic resonance imaging (MRI). TA has been successfully applied clinically to improve identification of abnormalities in the brain, liver, and bone and, more recently, has been used to enhance the specificity of breast MRI. This preclinical study used a custom‐made phantom containing different grades of reticulated foam embedded in agarose gel to assess the capability of TA to distinguish between different texture objects, under different imaging conditions. The aim was to assess whether TA could be used reliably with clinical protocols that were not optimized for texture analysis and also to investigate the effect that changing imaging sequence parameters would have on the outcome of TA.Methods:Clinical fast gradient echo sequences and two different breast RF coils were used in order to reflect standard clinical practice. Three protocols were used: (1) a high spatial resolution protocol run on a 1.5 Tesla (T) MRI scanner, (2) a parameter matched sequence run on a 3.0 T magnet, and (3) a high temporal resolution protocol also run on a 3.0 T magnet.For each protocol, three sequence parameters (repetition time, bandwidth/echo time, and flip angle) were altered from the baseline values to assess the impact of changes in acquisition parameters on the outcome of TA.Results:TA was performed usingMAZDA software and clearly differentiated four foam phantoms when using the wavelet transform method (WAV), also moderately so with the co‐occurrence matrix method (COM). The outcome was generally improved for imaging protocols acquired on the 3.0 T scanner, particularly for the high spatial resolution protocol where changes to the acquisition parameters influenced the TA, especially changes to the bandwidth/echo time. For the other protocols, TA outcome was less affected by changes to the imaging parameters.Conclusions:This phantom study shows that acquisition parameters and protocols that are typically used for clinical breast imaging can result in good TA. Our findings suggest that changes to sequence parameters may not greatly influence the outcome of texture analysis, but rather that spatial resolution may be the most important factor to consider.
Studies of the structure and the atomic diffusion properties of the Σ = 5 [001] twist GB in B2-type intermetallic compound NiAl
Authors: Wen Yan-Ni , Zhang Jian-Min 
Published: August 2011

The structural properties, the formation energies and the atoms’ diffusion behaviors by vacancy mechanism near the Σ = 5 [001] twist GB of the B2-type intermetallic compound NiAl have been investigated by using the modified analytical embedded-atom method and a molecular dynamics simulation. Both the largest displacement and rippling effect occur at the first layer near the GB. The Ni vacancies at uncoincident sites are most easily formed on the first and second layers of the Ni- and Al-terminations, respectively. Furthermore, the Ni vacancy at an uncoincident site on the second layer of the Al-termination tends to migrate to the coincident Ni site of the first layer of the Ni-termination along a six-step jump path. The Ni vacancies at either the coincident or uncoincident site of the first layer tend to migrate in the first layer and finally return to their original site. Therefore, there is a collective tendency for the Ni vacancies to appear in the GB without local disorder.