bluuebunny/crossref_metadata_2025 huggingface dataset:
The regulation of constructive learning processes
Authors: Vermunt Jan D.
Published: May 2011

Background. Classical instructional design theories and constructivist theories disagree on the issue of how high‐quality learning can be realised. Research on student learning has identified a large number of learning components, but the problems of overlap among conceptualisations and the direction of interrelations among constructs have received little attention.

Aims. The main aims of this study were: increasing integration of existing models of student learning; gaining understanding of the regulation of constructive learning processes; and investigating the degree to which these phenomena generalise across contexts.

Samples. A total of 717 students from an open university (OU) and 795 students from a regular university (RU), from various academic disciplines, participated in the studies. The mean age of the OU students was 36.2 years and of the RU students 22.5 years.

Methods. Based on phenomenographic studies, a diagnostic instrument was constructed that covered four learning components: cognitive processing, metacognitive regulation, mental learning models, and learning orientations. It was administered to all students from the samples. Factor analyses on the data were conducted to achieve a more integrated model of student learning. Regression analyses were performed to study the directionality in the regulation of learning processes.

Results. Four learning dimensions were consistently found: an undirected, reproduction‐directed, meaning‐directed and application‐directed style. These styles consisted of typical combinations of learning components. Moreover, students' use of constructive processing strategies was explained much better by self‐regulation of learning than by external regulation. These findings were almost identical at both educational institutions, indicating a high degree of generalisability.

Conclusions. The integrated model of student learning developed in this study can reduce the overlap among learning component conceptualisations considerably. The results stress the importance of process‐oriented teaching models for improving the quality of student learning.
Affective variables, learning approaches and academic achievement: a causal modelling investigation with Hong Kong tertiary students
Authors: Drew Po Yin , Watkins David
Published: May 2011

Background. Academic learning outcomes are believed to be influenced by a complex system that involves the interaction of student personality characteristics and learning processes. Yet to date there have been few studies, particularly in a non‐western culture, which have examined the interrelationships between these variables and their causal effects on achievement outcomes.

Aims. This study aims to investigate the interrelationships of affective variables, learning approaches and academic achievement. It was hypothesised that academic causal attributions and academic self‐concept affected the learning approaches the students adopted and subsequently influenced achievement outcomes.

Sample. The participants were 162 male and female Hong Kong Chinese university students who enrolled in first year full‐time Nursing, Radiography, and Language and Communication courses. Their average age was 20 years.

Methods. Measures of academic causal attributions, academic self‐concept, learning approaches and academic achievement were obtained. Structural equation modelling (SEM) techniques were used to test the relationships among the variables.

Results. It was shown that as predicted, both academic causal attributions and academic self‐concept influenced academic achievement indirectly via students' learning approaches. Locus of control was significantly and negatively related to the surface approach to studying while academic self‐concept had a positive significant influence on the deep approach. Both the surface and the deep approaches to studying showed significant direct effects on academic achievement.

Conclusions. The findings supported the theoretical notion that personality variables influence students' learning processes and subsequently their academic achievement. The findings also lend support to attributional retraining, self‐concept enhancement interventions and development of self‐regulated learning strategies to improve different aspects of student learning.
Scottish and Australian teacher stress and strain: a comparative study
Authors: Pithers R.T. , Soden Rebecca
Published: May 2011

Background. There is a widespread belief that teacher stress is a serious problem with obvious implications for teachers' physical and psychological health status as well as performance. There is much published research about teacher stress, although not about cultural or national group comparisons.

Aim. This study examines the occupational stress, strain and personal coping resources of a comparative group of Scottish and Australian vocational teachers.

Sample. Three hundred and thirty two Scottish and Australian vocational and further education teachers.

Method. A standardised test, the Occupational Stress Inventory, was used to gather the data.

Results and Conclusions. Overall it was found that stress and strain similarities between the two national groups far outweighed the differences. For instance, there were no between‐group differences in strain levels, which were found to be at ‘average’ levels for both groups. Nevertheless, for both groups of teachers, role overload appeared to be a strong source of occupational stress.
Willcoxson and Prosser's factor analyses on Kolb's (1985) LSI data: reflections and re‐analyses
Authors: Yahya Ibramsha
Published: May 2011

Background. Willcoxson & Prosser's (1996) factor analyses provide partial evidence for the existence of Kolb's (1985) two bipolar dimensions while their correlation analysis provides complete evidence.

Aims. Based on this discrepancy, coupled with past research evidence, the present writer aims to clarify some problems in the factor analyses conducted by Willcoxson and Prosser by re‐analysing the correlation matrix.

Methods. The present re‐analyses investigated both the two‐ and three‐factor solutions.

Results. The two‐factor solution was found to be preferable.

Conclusions. In all, the factor analysis, appropriately conducted, provides strong and complete evidence for the validity of Kolb's two bipolar dimensions, not just partial evidence as found out by Willcoxson and Prosser.
Paired reading: effects of a parent involvement programme in a disadvantaged community in South Africa
Authors: Overett Jennifer , Donald David
Published: May 2011

Background. The study was conducted in an educationally disadvantaged South African community where the effectiveness of a paired reading parent involvement programme, which stressed interaction around reading as a means of mediating meaning, was evaluated.

Aims. The research aimed to evaluate whether reading accuracy, comprehension and attitude were promoted through involving parents and other family members as mediators in a process of paired reading. Further, it aimed to elucidate interactive ecosystemic effects across family, school and community levels.

Samples. Two complete grade four classes (29 and 32 children respectively) served as comparison groups (average age: 9 years 7 months).

Methods. To test the significance of the improvement in reading accuracy and comprehension (Neale Analysis of Reading Ability: Neale, 1966) and attitude (Elementary Reading Attitude Survey: McKenna & Kear, 1990) for the experimental group relative to the control, one‐tailed t‐tests for independent samples on the respective pre‐test/post‐test difference scores were applied.

Results. Statistically significant improvements in reading accuracy and comprehension, as well as reading attitude and involvement, were demonstrated. A broad ecosystemic analysis suggested that positive relationships between children and significant others in the family were nurtured and other children in the family were benefiting. Interactions between family and school, and school and the local community library, were also enhanced.

Conclusions. The study emphasises the importance of developing mediation insights and skills in parent involvement programmes, and the place of ecosystemic analysis in understanding the social dynamics involved in such programmes.
Third graders' acquisition of knowledge of banking: restructuring or accretion?
Authors: Berti Anna Emilia , Monaci Maria Grazia
Published: May 2011

Background. Some scholars maintain that similar processes intervene in children's cognitive development and in the history of science. According to Carey (1985), radical conceptual restructurings taking place during ontogenesis are the counterpart of scientific revolutions. Other authors object that individual cognitive development is only of an incremental type and shows no resemblance to scientific revolutions.

Aims. The main aim was to investigate whether a radical restructuring in children's conceptions of banking can be produced in a short time through explicit teaching.

Sample. A total of 58 third grade middle‐class children participated.

Method. A curriculum on the notion of banking (involving deposits, loans, interest, and their relations) was implemented in a third grade class of 25 children. The curriculum lasted about 20 hours, distributed over two months. Two post‐tests were carried out — a week and four months later — on both the experimental and the control group who received no training.

Results. Most children in the experimental group acquired and retained an understanding of banking. Only very limited progress was shown instead by the control group.

Conclusion. The comparison between children's conceptions before and after teaching suggests that a conceptual restructuring had occurred. The way this result was achieved shows that restructuring should be viewed as the end product of changes of an incremental type rather than as a distinct process.
Pupil‐class determinants of aggressive and victim behaviour in pupils
Authors: Mooij Ton
Published: May 2011

Background. Aggressive behaviour in pupils is expressed in, e.g., bullying, sexual harassment, and violence. Different kinds of variables could be relevant in explaining a pupil's aggressive or victim behaviour.

Aims. To develop a multilevel theoretical and empirical explanation for different kinds of aggressive and victim behaviour displayed by pupils in a classroom and school environment.

Samples. A national survey was carried out to identify different kinds of aggressive and victim behaviour displayed by pupils and to assess other variables related to pupils, classes, and schools. A total of 1998 pupils from 100 third and fourth year classes attending 71 different secondary schools took part in the research.

Methods. Data were analysed by a series of secondary multilevel analyses using the MLA‐program.

Results. Being a boy, being more extravert, being more disagreeable, coming across fewer teachers with positive teaching behaviour, and attending a lower type of secondary school, help explain why someone is a perpetrator as such. Being a boy, being more disagreeable, being more emotionally unstable, being open to new ideas, and seeing more teachers as being strict, function as explanatory pupil variables for victim behaviour. Other pupil level variables determine more specific aggressive and victim behaviour aspects. Various other class level and school level variables are relevant, too.

Conclusions. Personal and environmental pupil variables are more important than class variables but class variables are in turn more important than school variables in explaining a pupil's aggressive and victim behaviour.
Learning styles: a cross‐sectional and longitudinal study in higher education
Authors: Busato Vittorio V. , Prins Frans J. , Elshout Jan J. , Hamaker Christiaan
Published: May 2011

Background. In his dissertation, Jan Vermunt (1992) proposed four different learning styles: a meaning directed, a reproduction directed, an application directed and an undirected style.

Aims. In a cross‐sectional and longitudinal design the development of these learning styles during students' stay at the university is studied, as well as the relation of these styles with academic success. A systematic relation between year of study and learning style is expected, namely that the application and meaning directed learning style scores would be higher in the later years and the undirected and reproduction learning style scores would be the highest in the early years.

Results. In the cross‐sectional study it was not found that the application and meaning directed learning style scores were higher in the later years, nor that the undirected and reproduction learning style scores were the highest in the early years. In the longitudinal study the means of the meaning directed and application directed learning style scores indeed increased over the years, while the means of the reproduction and undirected learning style scores decreased. For the score on the meaning directed learning style, this change was significant, though a marginal effect size was found.

Conclusion. It might not be concluded there is a systematic relation between year of study and learning style. No evidence is found for the implicit hierarchy that the meaning directed and application directed learning are better than the reproduction learning style. The undirected learning style, however, correlates negatively with academic success.
An evaluation of structured abstracts in journals published by the British Psychological Society
Authors: Hartley James , Benjamin Michele
Published: May 2011

Background. In 1997 four journals published by the British Psychological Society — the British Journal of Clinical Psychology, the British Journal of Educational Psychology, the British Journal of Health Psychology, and Legal and Criminological Psychology — began publishing structured abstracts.

Aims. The aim of the studies reported here was to assess the effectiveness of these structured abstracts by comparing them with original versions written in a traditional, unstructured, format.

Method. The authors of articles accepted for publication in the four journals were asked to supply copies of their original traditional abstracts (written when the paper was submitted) together with copies of their structured abstracts (when the paper was revised). 48 such requests were made, and 30 pairs of abstracts were obtained. These abstracts were then compared on a number of measures.

Results. Analysis showed that the structured abstracts were significantly more readable, significantly longer, and significantly more informative than the traditional ones. Judges assessed the contents of the structured abstracts more quickly and with significantly less difficulty than they did the traditional ones. Almost every respondent expressed positive attitudes to structured abstracts.

Conclusions. The structured abstracts fared significantly better than the traditional ones on every measure used in this enquiry. We recommend, therefore, that the editors of other journals in the social sciences consider adopting structured abstracts.
An intervention programme for children with moderate learning difficulties
Authors: Lamb Susannah J. , Bibby Peter A. , Wood David J. , Leyden Gervase
Published: May 2011

Background. Children with learning difficulties typically demonstrate problems generalising what they have learned in specific contexts to new situations. Intervention programmes that teach children regulatory skills have been shown to overcome these problems for children with reading difficulties. This study applies the principles that underlie such interventions to the design of a programme for children with more general learning difficulties.

Aim. The aim of the study reported here was to design and evaluate an intervention programme which would facilitate the transfer of skills learned over the course of the intervention to different types of task.

Sample. A total of 41 children (aged 13–16 yrs; 14 females, 27 males) with moderate learning difficulties participated in the intervention programme.

Method. The children participated in a twelve‐week intervention programme designed to promote regulatory strategies over a range of activities. The children worked in pairs and were guided by an adult who provided explicit instruction and modelled appropriate strategies. The children were assessed before and after the programme to determine whether improvements in strategic behaviour were evident and whether this generalised to new situations.

Results. Gains made in regulatory skills over the course of the intervention were accompanied by improvements in other performance measures such as reading and IQ.

Conclusions. Even after a relatively short intervention, which focused on the development of regulatory skills, significant improvements on a range of tasks were observed for a group of children with moderate learning difficulties.
Pupils' explanations of seasonal changes: age differences and the influence of teaching
Authors: Kikas Eve
Published: May 2011

Background. Pupils have consistent everyday astronomical explanations, some of which, e.g., distance theory, are very resistant to change. The reasons why everyday explanations are not replaced by scientific ones have been connected with teaching methods used in school.

Aims. The developmental differences in explaining seasonal changes and the reasons why school teaching fails in changing distance theory are studied.

Samples. The 112 schoolchildren participating in the study were: 32 pupils from each of grade 3 (age 9–10), grade 5 (age 11–12) and grade 7 (age 13–14) (half of them from a state school, others from Waldorf school) and 16 pupils from grade 9 (age 15–16). Half of the pupils were boys. The participants were divided into groups of four same‐sex and same‐grade pupils (i.e., into 28 groups).

Methods. Guided peer discussions in foursomes are used. Explanations of pupils of different ages and from two schools with different teaching methods are compared.

Results. The sources of references on which pupils based their explanations were divided into five categories: everyday, distance‐theory, incomplete, exact rules and authoritative. It is shown that younger pupils refer more frequently to everyday perceptible data and older ones more to knowledge taught in school but using distance theory does not change with age. Differences between schools were determined.

Conclusions. Such an everyday explanation as distance theory is very vital as it is drawn from several everyday experiences with heat sources. It is used to explain seasonal changes as far as scientific explanations learnt in school have not been well understood or have been forgotten.
A multilevel meta‐analysis of gender differences in learning orientations
Authors: Severiens Sabine , ten Dam Geert
Published: May 2011

Background. Reviewing gender differences in learning processes does not result in a clear and coherent picture of the magnitude and direction of gender differences (Severiens & ten Dam, 1994). The results not only differ on several dimensions but at times they are actually contradictory.

Aims. The aim of the present study is to obtain a more coherent picture of gender differences in learning orientations.

Samples. To provide this picture, a meta‐analysis was performed on 22 studies which investigate gender differences in learning orientations. The studies used Entwistle's Approaches to Studying Inventory, and were conducted in a variety of higher education settings.

Methods. The results of these studies were analysed in a multilevel approach with two levels: the respondents are nested within studies.

Results. Results show significant mean gender differences on the Reproduction Orientation (women score higher), and on the Non‐academic Orientation (men score higher). Furthermore, gender differences appeared on 11 of 16 scales (e.g., relating ideas, operational learning, fear of failure, negative attitude to studying, extrinsic motivation). The effect scores of 10 of 16 scales of the ASI are heterogeneous. The observed variation in gender differences across studies could not be explained by the small number of available study characteristics.

Conclusions. More research is needed which explores factors in the educational context ‘responsible’ for the magnitude and direction of gender differences in learning orientations.
Identification of Rotordynamic Force Coefficients of a Metal Mesh Foil Bearing Using Impact Load Excitations
Authors: San Andrés Luis , Chirathadam Thomas Abraham
Published: May 2011

Metal mesh foil bearings (MMFBs) are inexpensive compliant gas bearing type that aim to enable high speed, high temperature operation of small turbomachinery. A MMFB with an inner diameter of 28.00 mm and length of 28.05 mm is constructed with low cost and common materials. The bearing incorporates a copper mesh ring, 20% in compactness, and offering large material damping beneath a 0.127 mm thick preformed top foil. Prior experimentations (published papers) provide the bearing structure force coefficients and the break away torque for bearing lift off. Presently, the MMFB replaces a compressor in a small turbocharger driven test rig. Impact load tests aid to identify the direct and cross-coupled rotor dynamic force coefficients of the floating MMFB while operating at a speed of 50 krpm. Tests conducted with and without shaft rotation show the MMFB direct stiffness is less than its structural (static) stiffness, ∼25% lower at an excitation frequency of 200 Hz. The thin air film acting in series with the metal mesh support and separating the rotating shaft and the bearing inner surface while airborne reduces the bearing stiffness. The equivalent viscous damping is nearly identical with and without shaft rotation. The identified loss factor, best representing the hysteretic type damping from the metal mesh, is high at ∼0.50 in the frequency range 0–200 Hz. This magnitude reveals large mechanical energy dissipation ability from the MMFB. The measurements also show appreciable cross directional motions from the unidirectional impact loads, thus generating appreciable cross-coupled force coefficients. Rotor speed coast down measurements reveal pronounced subsynchronous whirl motion amplitudes locked at distinct frequencies. The MMFB stiffness hardening nonlinearity produces the rich frequency forced response. The synchronous as well as subsynchronous motions peak while the shaft traverses its critical speeds. The measurements establish reliable operation of the test MMFB while airborne.
A Kantian argument against comparatively advantageous genetic modification
Authors: Jensen David
Published: May 2011

The genetic modification of children is becoming a more likely possibility given our rapid progress in medical technologies. I argue, from a broadly Kantian point of view, that at least one kind of such modification—modification by a parent for the sake of a child's comparative advantage—is not rationally justified. To argue this, I first characterize a necessary condition on reasons and rational justification: what is a reason for an agent to do an action in one set of circumstances must be a reason for any in those circumstances to do the action. I then show that comparatively advantageous genetic modification violates this principle since a child's “getting ahead” through genetic modification cannot be rationally justified unless other children also could receive the modification, thus rendering the advantage useless. Finally, I consider the major objection to this conclusion: it seems to disallow all cases of a parent's helping a child get ahead, something that parents normally engage in with their children. I argue that typical practices of developing a comparative advantage in a child, as well as practices of societal competition in general, do not conflict because they involve circumstances that mitigate the universal character of reasons. Many ordinary cases of competitive advantage that we think of as unjust, in fact, can be explained by my argument.
ENERGY CONCENTRATION FOR 2-DIMENSIONAL RADIALLY SYMMETRIC EQUIVARIANT HARMONIC MAP HEAT FLOWS
Authors: BERTSCH MICHIEL , VAN DER HOUT REIN , HULSHOF JOSEPHUS
Published: May 2011

We give a description of singularity formation in terms of energy quanta for 2-dimensional radially symmetric equivariant harmonic map heat flows. Adapting Struwe's energy method we first establish a finite bubble tree result with a discrete multiple of energy quanta disappearing in the singularity. We then use intersection-comparison arguments to show that the bubble tree consists of a single bubble only and that there is a well defined scale RBHK(t) ↓ 0 in which the solution converges to the standard harmonic map.
QUASILINEAR ELLIPTIC EQUATIONS WITH SINGULAR QUADRATIC GROWTH TERMS
Authors: BOCCARDO LUCIO , LEONORI TOMMASO , ORSINA LUIGI , PETITTA FRANCESCO
Published: May 2011

In this paper, we deal with positive solutions for singular quasilinear problems whose model is [Formula: see text] where Ω is a bounded open set of ℝN, g ≥ 0 is a function in some Lebesgue space, and γ > 0. We prove both existence and nonexistence of solutions depending on the value of γ and on the size of g.
SMOOTH K-THEORY OF LOCALLY CONVEX ALGEBRAS
Authors: INASSARIDZE HVEDRI , KANDELAKI TAMAZ
Published: May 2011

Smooth K-functors are introduced and the smooth K-theory of locally convex algebras is developed. It is proved that the algebraic and smooth K-functors are isomorphic on the category of quasi [Formula: see text]-stable real (or complex) Fréchet algebras.
MULTIPLICITY OF SOLUTIONS FOR SEMILINEAR ELLIPTIC PROBLEMS WITH COMBINED NONLINEARITIES
Authors: CHANG XIAO JUN
Published: May 2011

In this paper, we are concerned with the semilinear elliptic problem [Formula: see text] where Ω is a bounded smooth domain in Rm(m ≥ 2), h ∈ L∞(Ω), h(x) ≢ 0, 1 < q < 2, [Formula: see text]. When the nonlinearity f satisfies the Ambrosetti–Prodi type condition at infinity, two multiplicity results are established by using a combination of variational methods, upper and lower solutions, Leray–Schauder degree theory and suitable truncation techniques.
INTEGRAL FORMULATION OF 3D NAVIER–STOKES AND LONGER TIME EXISTENCE OF SMOOTH SOLUTIONS
Authors: COSTIN O. , LUO G. , TANVEER S.
Published: May 2011

We extend Borel summability methods to the analysis of the 3D Navier–Stokes initial value problem, [Formula: see text] where [Formula: see text] is the Hodge projection to divergence-free vector fields. We assume that the Fourier transform norms [Formula: see text] and [Formula: see text] are finite. We prove that the integral equation obtained from (*) by Borel transform and Écalle acceleration, Û (k, q), is exponentially bounded for q in a sector centered on ℝ+, where q is the inverse Laplace dual to 1/tnfor n ≥ 1.

This implies in particular local existence of a classical solution to (*) for t ∈ (0, T), where T depends on [Formula: see text] and [Formula: see text]. Global existence of the solution to NS follows if ‖Û(⋅, q)‖l1has subexponential bounds as q → ∞.

If f = 0, then the converse is also true: if NS has global solution, then there exists n ≥ 1 for which ‖Û(⋅, q)‖ necessarily decays. More generally, if the exponential growth rate in q of Û is α, then a classical solution to NS exists for t ∈ (0, α-1/n).

We show that α can be better estimated based on the values of Û on a finite interval [0, q0]. We also show how the integral equation can be solved numerically with controlled errors.

Preliminary numerical calculations of the integral equation over a modest [0, 10], q-interval for n = 2 corresponding to Kida ([21]) initial conditions, though far from being optimized or rigorously controlled, suggest that this approach gives an existence time for 3D Navier–Stokes that substantially exceeds classical estimate.
RADIAL SYMMETRY OF MINIMAX CRITICAL POINTS FOR NONSMOOTH FUNCTIONALS
Authors: SQUASSINA MARCO
Published: May 2011

We obtain the existence of radially symmetric and decreasing solutions to a general class of quasi-linear elliptic problems by a nonsmooth version of a symmetric minimax principle recently obtained by Van Schaftingen.
THE Cα REGULARITY OF A CLASS OF ULTRAPARABOLIC EQUATIONS
Authors: ZHANG LIQUN
Published: May 2011

We prove the Cα regularity for weak solutions to a class of ultraparabolic equation, with measurable coefficients. The result generalized our recent Cα regularity results of Prandtl's system to high dimensional cases.
CRITICAL POINTS OF YANG–MILLS–HIGGS FUNCTIONAL
Authors: SONG CHONG
Published: May 2011

We use Sacks–Uhlenbeck's perturbation method to find critical points of the Yang–Mills–Higgs functional on fiber bundles with 2-dimensional base manifolds. Such critical points can be regarded as a generalization of harmonic maps from surfaces, and also a generalization of the so-called twisted holomorphic maps [15]. We prove an existence result analogous to the one for harmonic maps. In particular, we show that the so-called energy identity holds for the Yang–Mills–Higgs functional.
CONSTRUCTION AND APPLICATIONS OF BIORTHOGONAL TERNARY LOOP SUBDIVISION WAVELETS
Authors: XUE YAOHONG , LIANG XUEZHANG , LI QIANG
Published: May 2011

In this paper, we present an efficient biorthogonal wavelet construction for the ternary Loop subdivision based on the lifting scheme, and give the corresponding decomposition and reconstruction formulas. We apply the proposed algorithm to the progressive transmission and the denoising of 3D graphics, and show its sufficient stability and good performance by some numerical experiments. Since the usual input mesh does not possess the property of subdivision connectivity, while the multiresolution analysis based on subdivision surface requires the processed initial mesh to be semi-regular, we further propose a new rapid algorithm of constructing the initial mesh which not only possesses ternary subdivision connectivity but also approximates the given input mesh.
TERNARY INTERPOLATORY SUBDIVISION SCHEMES ORIGINATED FROM SPLINES
Authors: AVERBUCH AMIR Z. , ZHELUDEV VALERY A. , FATAKHOV GARY B. , YAKUBOV EDUARD H.
Published: May 2011

A generic technique for construction of ternary interpolatory subdivision schemes, which is based on polynomial and discrete splines, is presented. These schemes have rational symbols. The symbols are explicitly presented in the paper. This is accompanied by a detailed description of the design of the refinement masks and by algorithms that verify the convergence of these schemes. In addition, the smoothness of the limit functions is investigated. The ternary subdivision schemes, whose construction is based on continuous splines, become tools for fast computation ofıory s of arbitrary order at triadic rational points.
DESIGN OF AN OPTIMAL PREVIEW CONTROLLER FOR CONTINUOUS-TIME SYSTEMS
Authors: LIAO FUCHENG , TANG YUAN YAN , LIU HEPING , WANG YUNJIAN
Published: May 2011

This paper studies the preview control problem for continuous-time control systems. A design method for an optimal preview controller is presented, when the desired tracking and disturbance are piecewise-continuously differentiable functions. Applying the same techniques as for optimal control in linear quadratic optimal control, we derive a type-one servomechanism with both desired tracking preview and disturbance preview compensation. A proof is presented that if the original system is stabilizable and detectable, the closed-loop system is asymptotically stable. We also design a full-dimensional state observer for the considered system. Finally, numerical simulations show the efficiency of the controller.
STRONGLY SINGULAR CONVOLUTION OPERATORS ON MODULATION SPACES
Authors: CHENG MEIFANG , ZHANG ZHENQIU
Published: May 2011

The purpose of this paper is to investigate the mapping properties of the strongly singular convolution operators on general weighted modulation spaces [Formula: see text] for 0 < p ≤ ∞, 0 < q ≤ ∞ and s ∈ ℝ. Our results show that modulation spaces are good substitutions for Lebesgue spaces.
Identification of differentially expressed proteins in ruminal epithelium in response to a concentrate-supplemented diet
Authors: Bondzio Angelika , Gabler Christoph , Badewien-Rentzsch Brit , Schulze Petra , Martens Holger , Einspanier Ralf
Published: May 2011

Ruminal epithelium adapts to dietary change with well-coordinated alterations in metabolism, proliferation, and permeability. To further understand the molecular events controlling diet effects, the aim of this study was to evaluate protein expression patterns of ruminal epithelium in response to various feeding regimes. Sheep were fed with a concentrate-supplemented diet for up to 6 wk. The control group received hay only. Proteome analysis with differential in gel electrophoresis technology revealed that, after 2 days, 60 proteins were significantly modulated in ruminal epithelium in a comparison between hay-fed and concentrate-fed sheep ( P < 0.05). Forty proteins were upregulated and 20 proteins were downregulated in response to concentrate diet. After 6 wk of this diet, only 14 proteins were differentially expressed. Among these, 11 proteins were upregulated and 3 downregulated. To identify proteins that were modulated by dietary change, two-dimensional electrophoresis was coupled with liquid chromatography electrospray ionization mass spectrometry. The differential expression of selected proteins, such as esterase D, annexin 5, peroxiredoxin 6, carbonic anhydrase I, and actin-related protein 3, was verified by immunoblotting and/or mRNA analysis. The identified proteins were mainly associated with functions related to cellular stress, metabolism, and differentiation. These results suggest new candidate proteins that may contribute to a better understanding of the signaling pathways and mechanisms that mediate rumen epithelial adaptation to high-concentrate diet.
TNF transactivation of EGFR stimulates cytoprotective COX-2 expression in gastrointestinal epithelial cells
Authors: Hobbs Stuart S. , Goettel Jeremy A. , Liang Dongchun , Yan Fang , Edelblum Karen L. , Frey Mark R. , Mullane Matthew T. , Polk D. Brent
Published: May 2011

TNF and epidermal growth factor (EGF) are well-known stimuli of cyclooxygenase (COX)-2 expression, and TNF stimulates transactivation of EGF receptor (EGFR) signaling to promote survival in colon epithelial cells. We hypothesized that COX-2 induction and cell survival signaling downstream of TNF are mediated by EGFR transactivation. TNF treatment was more cytotoxic to COX-2−/−mouse colon epithelial (MCE) cells than wild-type (WT) young adult mouse colon (YAMC) epithelial cells or COX-1−/−cells. TNF also induced COX-2 protein and mRNA expression in YAMC cells, but blockade of EGFR kinase activity or expression inhibited COX-2 upregulation. TNF-induced COX-2 expression was reduced and absent in EGFR−/−and TNF receptor-1 (TNFR1) knockout MCE cells, respectively, but was restored upon expression of the WT receptors. Inhibition of mediators of EGFR transactivation, Src family kinases and p38 MAPK, blocked TNF-induced COX-2 protein and mRNA expression. Finally, TNF injection increased COX-2 expression in colon epithelium of WT, but not kinase-defective EGFRwa2and EGFRwa5, mice. These data indicate that TNFR1-dependent transactivation of EGFR through a p38- and/or an Src-dependent mechanism stimulates COX-2 expression to promote cell survival. This highlights an EGFR-dependent cell signaling pathway and response that may be significant in colitis-associated carcinoma.
Decreased specific force and power production of muscle fibers from myostatin-deficient mice are associated with a suppression of protein degradation
Authors: Mendias Christopher L. , Kayupov Erdan , Bradley Joshua R. , Brooks Susan V. , Claflin Dennis R.
Published: May 2011

Myostatin ( MSTN) is a member of the transforming growth factor-β superfamily of cytokines and is a negative regulator of skeletal muscle mass. Compared with MSTN+/+mice, the extensor digitorum longus muscles of MSTN−/−mice exhibit hypertrophy, hyperplasia, and greater maximum isometric force production (Fo), but decreased specific maximum isometric force (sFo; Fonormalized by muscle cross-sectional area). The reason for the reduction in sFowas not known. Studies in myotubes indicate that inhibiting myostatin may increase muscle mass by decreasing the expression of the E3 ubiquitin ligase atrogin-1, which could impact the force-generating capacity and size of muscle fibers. To gain a greater understanding of the influence of myostatin on muscle contractility, we determined the impact of myostatin deficiency on the contractility of permeabilized muscle fibers and on the levels of atrogin-1 and ubiquitinated myosin heavy chain in whole muscle. We hypothesized that single fibers from MSTN−/−mice have a greater Fo, but no difference in sFo, and a decrease in atrogin-1 and ubiquitin-tagged myosin heavy chain levels. The results indicated that fibers from MSTN−/−mice have a greater cross-sectional area, but do not have a greater Foand have a sFothat is significantly lower than fibers from MSTN+/+mice. The extensor digitorum longus muscles from MSTN−/−mice also have reduced levels of atrogin-1 and ubiquitinated myosin heavy chain. These findings suggest that myostatin inhibition in otherwise healthy muscle increases the size of muscle fibers and decreases atrogin-1 levels, but does not increase the force production of individual muscle fibers.
Do genetic variations alter the effects of exercise training on cardiovascular disease and can we identify the candidate variants now or in the future?
Authors: Hagberg James M.
Published: May 2011

Cardiovascular disease (CVD) and CVD risk factors are highly heritable, and numerous lines of evidence indicate they have a strong genetic basis. While there is nothing known about the interactive effects of genetics and exercise training on CVD itself, there is at least some literature addressing their interactive effect on CVD risk factors. There is some evidence indicating that CVD risk factor responses to exercise training are also heritable and, thus, may have a genetic basis. While roughly 100 studies have reported significant effects of genetic variants on CVD risk factor responses to exercise training, no definitive conclusions can be generated at the present time, because of the lack of consistent and replicated results and the small sample sizes evident in most studies. There is some evidence supporting “possible” candidate genes that may affect these responses to exercise training: APO E and CETP for plasma lipoprotein-lipid profiles; eNOS, ACE, EDN1, and GNB3 for blood pressure; PPARG for type 2 diabetes phenotypes; and FTO and BAR genes for obesity-related phenotypes. However, while genotyping technologies and statistical methods are advancing rapidly, the primary limitation in this field is the need to generate what in terms of exercise intervention studies would be almost incomprehensible sample sizes. Most recent diabetes, obesity, and blood pressure genetic studies have utilized populations of 10,000–250,000 subjects, which result in the necessary statistical power to detect the magnitude of effects that would probably be expected for the impact of an individual gene on CVD risk factor responses to exercise training. Thus at this time it is difficult to see how this field will advance in the future to the point where robust, consistent, and replicated data are available to address these issues. However, the results of recent large-scale genomewide association studies for baseline CVD risk factors may drive future hypothesis-driven exercise training intervention studies in smaller populations addressing the impact of specific genetic variants on well-defined physiological phenotypes.
Airflow pattern complexity and airway obstruction in asthma
Authors: Veiga Juliana , Lopes Agnaldo J. , Jansen José M. , Melo Pedro L.
Published: May 2011

The scientific and clinical value of a measure of complexity is potentially enormous because complexity appears to be lost in the presence of illness. The authors examined the effect of elevated airway obstruction on the complexity of the airflow (Q) pattern of asthmatic patients analyzing the airflow approximate entropy (ApEnQ). This study involved 11 healthy controls, 11 asthmatics with normal spirometric exams, and 40 asthmatics with mild ( 14 ), moderate ( 14 ), and severe ( 12 ) airway obstructions. A significant ( P < 0.02) reduction in the ApEnQ was observed in the asthmatic patients. This reduction was significantly correlated with spirometric indexes of airway obstruction [FEV1 (%): R = 0.31, P = 0.013] and the total respiratory impedance ( R = −0.39; P < 0.002). These results are in close agreement with pathophysiological fundamentals and suggest that the airflow pattern becomes less complex in asthmatic patients, which may reduce the adaptability of the respiratory system to perform the exercise that is associated with daily life activities. This analysis was able to identify respiratory changes in patients with mild obstruction with an adequate accuracy (83%). Higher accuracies were obtained in patients with moderate and severe obstructions. The analysis of airflow pattern complexity by the ApEnQ was able to provide new information concerning the changes associated with asthma. In addition, this analysis was also able to contribute to the detection of the adverse effects of asthma. Because these measurements are easy to perform, such a technique may represent an alternative and/or a complement to other conventional exams to help the clinical evaluations of asthmatic patients.
Dynamic nonlinearity of lung tissue: frequency dependence and harmonic distortion
Authors: Romero Pablo V. , Faffe Débora S. , Cañete Concepción
Published: May 2011

Harmonic distortion (HD) is a simple approach to analyze lung tissue nonlinear phenomena. This study aimed to characterize frequency-dependent behavior of HD at several amplitudes in lung tissue strips from healthy rats and its influence on the parameters of linear analysis. Lung strips ( n = 17) were subjected to sinusoidal deformation at three different strain amplitudes (Δε) and fixed operational stress (12 hPa) among various frequencies, between 0.03 and 3 Hz. Input HD was <2% in all cases. The main findings in our study can be summarized as follows: 1) harmonic distortion of stress (HD) showed a positive frequency and amplitude dependence following a power law with frequency; 2) HD correlated significantly with the frequency response of dynamic elastance, seeming to converge to a limited range at an extrapolated point where HD=0; 3) the relationship between tissue damping (G) and HDω=1 (the harmonic distortion at ω=1 rad/s) was linear and accounted for a large part of the interindividual variability of G; 4) hysteresivity depended linearly on κ (the power law exponent of HD with ω); and 5) the error of the constant phase model could be corrected by taking into account the frequency dependence of harmonic distortion. We concluded that tissue elasticity and tissue damping are coupled at the level of the stress-bearing element and to the mechanisms underlying dynamic nonlinearity of lung tissue.
Tumor Suppressor miR-22 Determines p53-Dependent Cellular Fate through Post-transcriptional Regulation of p21
Authors: Tsuchiya Naoto , Izumiya Masashi , Ogata-Kawata Hiroko , Okamoto Koji , Fujiwara Yuko , Nakai Makiko , Okabe Atsushi , Schetter Aaron J. , Bowman Elise D. , Midorikawa Yutaka , Sugiyama Yasuyuki , Aburatani Hiroyuki , Harris Curtis C. , Nakagama Hitoshi
Published: May 2011

Selective activation of p53 target genes in response to various cellular stresses is a critical step in determining the ability to induce cell-cycle arrest or apoptosis. Here we report the identification of the microRNA miR-22 as a p53 target gene that selectively determines the induction of p53-dependent apoptosis by repressing p21. Combinatorial analyses of the AGO2 immunocomplex and gene expression profiles identified p21 as a direct target of miR-22. Induction of p21 was inhibited by miR-22 after exposure to the genotoxic agent Adriamycin (doxorubicin; Bedford Laboratories), sensitizing cells to p53-dependent apoptosis. Interestingly, the activation of miR-22 depended on the intensity of the stresses that induced cells to undergo apoptosis in the presence of p21 suppression. Our findings define an intrinsic molecular switch that determines p53-dependent cellular fate through post-transcriptional regulation of p21. Cancer Res; 71(13); 4628–39. ©2011 AACR.
Nicotinamide Blocks Proliferation and Induces Apoptosis of Chronic Lymphocytic Leukemia Cells through Activation of the p53/miR-34a/SIRT1 Tumor Suppressor Network
Authors: Audrito Valentina , Vaisitti Tiziana , Rossi Davide , Gottardi Daniela , D'Arena Giovanni , Laurenti Luca , Gaidano Gianluca , Malavasi Fabio , Deaglio Silvia
Published: May 2011

Because of its relatively indolent clinical course, chronic lymphocytic leukemia (CLL) offers a versatile model for testing novel therapeutic regimens and drug combinations. Nicotinamide is the main NAD+ precursor and a direct inhibitor of four classes of enzymes, including the sirtuins. SIRT1, the main member of the sirtuin family, inactivates p53 by deacetylating a critical lysine residue. In this study, we showed that CLL cells express high levels of functional SIRT1, which is inhibited by exogenous nicotinamide. This agent blocks proliferation and promotes apoptosis selectively in leukemic cells that express wild-type (wt) p53. Nicotinamide modulates the p53-dependent genes p21, NOXA, BAX, and Mcl-1, indicating an activation of the p53 pathway and of caspase-3. DNA-damaging chemotherapeutics, such as etoposide, activate a functional loop linking SIRT1 and p53 through the induction of miR-34a. When leukemic cells are simultaneously exposed to nicotinamide and etoposide, we observe a significant increase in miR-34a levels with a concomitant inhibition of SIRT1. Furthermore, p53 acetylation levels are higher than with either agent used alone. Overall, treatment with both nicotinamde and etoposide shows strongly synergistic effects in the induction of apoptosis. We therefore concluded that nicotinamide has the dual property of inhibiting SIRT1 through a noncompetitive enzymatic block (p53 independent) and at the same time through miR-34a induction (p53 dependent). These observations suggested the therapeutic potential of nicotinamide, a novel, safe, and inexpensive drug, to be used in addition to chemotherapy for CLL patients with wt p53. Cancer Res; 71(13); 4473–83. ©2011 AACR.