Home About us Contact
|
Home About us Contact | ||
|
|
||
Adaptive
Terms modified by Adaptive Selected AbstractsAdaptive and Feature-Preserving Subdivision for High-Quality Tetrahedral MeshesCOMPUTER GRAPHICS FORUM, Issue 1 2010D. Burkhart I.3.5 [Computer Graphics]: Curve, surface, solid, and object representations Abstract We present an adaptive subdivision scheme for unstructured tetrahedral meshes inspired by the, -subdivision scheme for triangular meshes. Existing tetrahedral subdivision schemes do not support adaptive refinement and have traditionally been driven by the need to generate smooth three-dimensional deformations of solids. These schemes use edge bisections to subdivide tetrahedra, which generates octahedra in addition to tetrahedra. To split octahedra into tetrahedra one routinely chooses a direction for the diagonals for the subdivision step. We propose a new topology-based refinement operator that generates only tetrahedra and supports adaptive refinement. Our tetrahedral subdivision algorithm is motivated by the need to have one representation for the modeling, the simulation and the visualization and so to bridge the gap between CAD and CAE. Our subdivision algorithm design emphasizes on geometric quality of the tetrahedral meshes, local and adaptive refinement operations, and preservation of sharp geometric features on the boundary and in the interior of the physical domain. [source] An Adaptive Conjugate Gradient Neural Network,Wavelet Model for Traffic Incident DetectionCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2000H. Adeli Artificial neural networks are known to be effective in solving problems involving pattern recognition and classification. The traffic incident-detection problem can be viewed as recognizing incident patterns from incident-free patterns. A neural network classifier has to be trained first using incident and incident-free traffic data. The dimensionality of the training input data is high, and the embedded incident characteristics are not easily detectable. In this article we present a computational model for automatic traffic incident detection using discrete wavelet transform, linear discriminant analysis, and neural networks. Wavelet transform and linear discriminant analysis are used for feature extraction, denoising, and effective preprocessing of data before an adaptive neural network model is used to make the traffic incident detection. Simulated as well as actual traffic data are used to test the model. For incidents with a duration of more than 5 minutes, the incident-detection model yields a detection rate of nearly 100 percent and a false-alarm rate of about 1 percent for two- or three-lane freeways. [source] Adaptive bang,bang control for the vibration control of structures under earthquakesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 13 2003C. W. Lim Abstract An adaptive method based on the modified bang,bang control algorithm is proposed for the vibration control of structures subjected to unexpected severe seismic loads greater than the design loads. A hydraulic-type active mass damper was made and experiments were carried out in the laboratory using a one-story test structure and a five-story test structure with the active mass damper. Through numerical simulations and experiments it was confirmed that the proposed method works well to suppress the vibration of structures subjected to unexpected severe seismic loads greater than the design loads without causing any unstable situations. Copyright © 2003 John Wiley & Sons, Ltd. [source] An Adaptive, Rate-Optimal Test of a Parametric Mean-Regression Model Against a Nonparametric AlternativeECONOMETRICA, Issue 3 2001Joel L. Horowitz We develop a new test of a parametric model of a conditional mean function against a nonparametric alternative. The test adapts to the unknown smoothness of the alternative model and is uniformly consistent against alternatives whose distance from the parametric model converges to zero at the fastest possible rate. This rate is slower than n,1/2. Some existing tests have nontrivial power against restricted classes of alternatives whose distance from the parametric model decreases at the rate n,1/2. There are, however, sequences of alternatives against which these tests are inconsistent and ours is consistent. As a consequence, there are alternative models for which the finite-sample power of our test greatly exceeds that of existing tests. This conclusion is illustrated by the results of some Monte Carlo experiments. [source] Adaptive versus non-adaptive phenotypic plasticity and the potential for contemporary adaptation in new environmentsFUNCTIONAL ECOLOGY, Issue 3 2007C. K. GHALAMBOR Summary 1The role of phenotypic plasticity in evolution has historically been a contentious issue because of debate over whether plasticity shields genotypes from selection or generates novel opportunities for selection to act. Because plasticity encompasses diverse adaptive and non-adaptive responses to environmental variation, no single conceptual framework adequately predicts the diverse roles of plasticity in evolutionary change. 2Different types of phenotypic plasticity can uniquely contribute to adaptive evolution when populations are faced with new or altered environments. Adaptive plasticity should promote establishment and persistence in a new environment, but depending on how close the plastic response is to the new favoured phenotypic optimum dictates whether directional selection will cause adaptive divergence between populations. Further, non-adaptive plasticity in response to stressful environments can result in a mean phenotypic response being further away from the favoured optimum or alternatively increase the variance around the mean due to the expression of cryptic genetic variation. The expression of cryptic genetic variation can facilitate adaptive evolution if by chance it results in a fitter phenotype. 3We conclude that adaptive plasticity that places populations close enough to a new phenotypic optimum for directional selection to act is the only plasticity that predictably enhances fitness and is most likely to facilitate adaptive evolution on ecological time-scales in new environments. However, this type of plasticity is likely to be the product of past selection on variation that may have been initially non-adaptive. 4We end with suggestions on how future empirical studies can be designed to better test the importance of different kinds of plasticity to adaptive evolution. [source] Sleep arrangements and night waking at 6 and 12 months in relation to infants' stress-induced cortisol responsesINFANT AND CHILD DEVELOPMENT, Issue 6 2009Rachel Lucas-Thompson Abstract The objective of this short-term longitudinal study was to examine the concurrent and prospective associations of infants' sleep arrangements and night waking with cortisol responses to an inoculation at 6 and 12 months, controlling for several key covariates. To our knowledge, this was the first study to concurrently and prospectively link proximity in sleep arrangements and night waking to physiological stress reactivity. A sample of 92 mother,infant dyads participated in the study when the infants were 6 and 12 months of age, although sample sizes were reduced for some analyses. Both proximal cosleeping arrangements and more frequent night wakings' were associated concurrently with an increased cortisol response to inoculations at both ages. Night waking at 6 months also was associated with a slightly increased cortisol response to inoculation at 12 months. Results aimed at exploring the direction of influence suggested that cosleeping and night waking may influence infant stress physiology rather than the reverse. Adaptive and maladaptive implications of infants' nocturnal experiences and greater stress-induced cortisol responses are discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Self-Assembled Perovskite-Fluorite Oblique Nanostructures for Adaptive (Tunable) ElectronicsADVANCED MATERIALS, Issue 13 2009Tomoaki Yamada The relative concentration of BaTiO3 and CeO2 is shown to control the inclination of composite growth. The oblique composite structures consist of tunable BaTiO3 nanofibers embedded in a CeO2 matrix, which lowers considerably the permittivity while significantly enhancing the tunable response to an electric field. This is of interest in reconfigurable microelectronics. [source] Adaptive least mean squares block Volterra filtersINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 4 2001Tarek I. Haweel Abstract Adaptive filtering has found many applications in situations where the underlying signals are changing or unknown. While linear filters are simple from implementation and conceptual points of view, many signals are non-linear in nature. Non-linear filters based on truncated Volterra expansions can effectively model a large number of systems. Unfortunately, the resulting input auto-moment matrix is ill conditioned, which results in a slow convergence rate. This paper proposes a class of block adaptive Volterra filters in which the input sequences are Hadamard transformed to improve the condition number of the input auto-moment matrix and consequently improve the convergence rate. This is achieved by the decorrelation effect produced by the orthogonality of the transform. Since Hadamard transformation employs only ±1's, the additional required computational and implementation burdens are few. The effect of additive white Gaussian noise is introduced. Simulation experiments are given to illustrate the improved performance of the proposed method over the conventional Volterra LMS method. Copyright © 2001 John Wiley & Sons, Ltd. [source] Adaptive and Generative Learning: Implications from Complexity TheoriesINTERNATIONAL JOURNAL OF MANAGEMENT REVIEWS, Issue 2 2010Ricardo Chiva One of the most important classical typologies within the organizational learning literature is the distinction between adaptive and generative learning. However, the processes of these types of learning, particularly the latter, have not been widely analyzed and incorporated into the organizational learning process. This paper puts forward a new understanding of adaptive and generative learning within organizations, grounded in some ideas from complexity theories: mainly self-organization and implicate order. Adaptive learning involves any improvement or development of the explicate order through a process of self-organization. Self-organization is a self-referential process characterized by logical deductive reasoning, concentration, discussion and improvement. Generative learning involves any approach to the implicate order through a process of self-transcendence. Self-transcendence is a holo-organizational process characterized by intuition, attention, dialogue and inquiry. The main implications of the two types of learning for organizational learning are discussed. [source] Adaptive/robust time-varying stabilization of second-order non-holonomic chained form with input uncertaintiesINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 15 2002B. L. Ma Abstract Adaptive and robust time-varying control schemes are constructed to stabilize second-order non-holonomic chained form in the presence of input uncertainties. The proposed control schemes guarantee that all the state variables converge to zero asymptotically in spite of input uncertainties, and are applied to the stabilization of a planar rigid body driven by active force and torque with unknown inertia and geometric parameters. The basic idea of the proposed stabilization schemes is to first convert the non-holonomic system into a linear time-varying form by time-varying co-ordinate transformation, and then design control laws to stabilize the converted linear time-varying system. Copyright © 2002 John Wiley & Sons, Ltd. [source] Ethics in operations research and sustainable developmentINTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH, Issue 4 2010Jean-Pierre Brans Abstract During the last 100 years, major social, economic, environmental and technical problems have arisen that today jeopardise mankind's very existence. The authors argue that operations research (OR) should be more strongly involved by developing models to face today's crucial challenges. OR should change drastically because it is traditionally involved mainly with optimisation problems, which are often counterproductive in the sense of ethical behaviour: new basic approaches are required. This paper provides some avenues on how to develop instruments for addressing mankind's sustainability problems, and for complying with ethical principles. It is proposed to have a mix of techniques, mainly: systems thinking, multi-criteria decision-making and dynamic control. A global framework, called ASMC (Adaptive, Systemic, Multi-criteria, Control procedure), is proposed for developing these ideas. Some sustainable development applications are presented. [source] Effects of Communicator Credibility and Fear on Adaptive and Maladaptive Coping Reactions to the HIV ThreatJOURNAL OF APPLIED BIOBEHAVIORAL RESEARCH, Issue 3 2005Kanayo Umeh Late diagnosis is currently the principal cause of continued mortality among HIV-infected people. Consequently, medical experts (i.e., GPs) are now required to play a more active role in promoting HIV prevention. Social psychological studies suggest that communicator credibility (CC) affects persuasion. However, there is a paucity of research focusing on HIV/AIDS. We tested propositions that a credible (i.e., "expert") communicator is more persuasive than a noncredible source, and that this effect is moderated by fear. Drive-reduction models (Hovland, Janis, & Kelley, 1953) provided the theoretic framework. One hundred undergraduates were exposed to a communication about HIV/AIDS. CC and fear arousal were manipulated with adaptive coping (intentions to use condoms) and maladaptive coping (rationalizations, denial) treated as outcome variables. Multivariate analysis of variance revealed neither a main effect of CC nor an interaction with fear. However, fear arousal seemed to negate persuasion by increasing maladaptive coping. The partial eta-squared (n,2) value indicated a weak-to-modest effect size. Overall, these findings echo drive-reduction models but raise new questions about relevance of source expertise in health persuasion. [source] Adaptive and maladaptive personality traits as predictors of violent and nonviolent offending behavior in men and womenAGGRESSIVE BEHAVIOR, Issue 3 2010Abigail J. Varley Thornton Abstract The aim of this study was to assess both violent and nonviolent offending behavior in a single, mixed-sex population. The rationale for this is that the two types of offending are usually researched separately, despite evidence that they overlap. A comprehensive measure of general violence, intimate partner violence (IPV), and nonviolent offending behavior was administered to 116 men and 181 women, together with measures of personality and personality disorder (PD) traits, to investigate whether predictors of violent and nonviolent offending were similar or different for men and women. Men were found to perpetrate higher levels of general violence and nonviolent offenses than women, but women perpetrated significantly more IPV than men. Cluster B PD traits predicted all three offense types for women and also men's general violence and nonviolent offending. Women's general violence and men's non-violence also had one unique risk factor each, low agreeableness, and low conscientiousness, respectively. The main difference was for IPV, where men's IPV was predicted by cluster A PD traits, indicating that men's and women's risk factors for IPV may be different, although their risk factors for the other offense types were fairly consistent. Aggr. Behav. 36:177,186, 2010. © 2010 Wiley-Liss, Inc. [source] Parenting stress in mothers of adults with an intellectual disability: parental cognitions in relation to child characteristics and family supportJOURNAL OF INTELLECTUAL DISABILITY RESEARCH, Issue 12 2009C. Hill Abstract Background There is a body of evidence that indicates that the cognitions of parents of children with intellectual disabilities (ID) play an important role in influencing parental stress. However, there is a paucity of evidence about the experience of parents of adult children with ID. This study sought to apply a model of parenting stress to mothers of adults with ID. Of particular interest were the parental cognitions of parenting self-esteem and parental locus of control. Method Face-to face interviews were administered with 44 mothers of adults with ID. They completed the Vineland Adaptive and Maladaptive Behaviour Scale, the Family Support Scale, the Parenting Sense of Competence Scale, a shortened version of the Parental Locus of Control Scale and the Parenting Stress Index. Results Correlations were observed between parenting stress and the other study variables. Regression analysis revealed that parental cognitive variables predicted 61% of the variance in parenting stress. Parenting satisfaction, a subscale of the measure of parenting sense of competence, mediated the relationships between adaptive behaviour and parenting stress and between family support and parenting stress. Conclusions These results indicate the importance of cognitive variables in the stress of mothers of adults with ID. Potential avenues of future research might focus on the experience of fathers and the impact of positive perceptions as a cognitive factor. [source] Infant Intersubjectivity: Research, Theory, and Clinical ApplicationsTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 1 2001Colwyn Trevarthen We review research evidence on the emergence and development of active " self-and-other " awareness in infancy, and examine the importance of its motives and emotions to mental health practice with children. This relates to how communication begins and develops in infancy, how it influences the individual subject's movement, perception, and learning, and how the infant's biologically grounded self-regulation of internal state and self-conscious purposefulness is sustained through active engagement with sympathetic others. Mutual selfother- consciousness is found to play the lead role in developing a child's cooperative intelligence for cultural learning and language. A variety of preconceptions have animated rival research traditions investigating infant communication and cognition. We distinguish the concept of " intersubjectivity ", and outline the history of its use in developmental research. The transforming body and brain of ahumanindividual grows in active engagement with an environment of human factors-organic at first, then psychological or inter-mental. Adaptive, human-responsive processes are generated first by interneuronal activity within the developing brain as formation of the human embryo is regulated in a support-system of maternal tissues. Neural structures are further elaborated with the benefit of intra-uterine stimuli in the foetus, then supported in the rapidly growing forebrain and cerebellum of the young child by experience of the intuitive responses of parents and other human companions. We focus particularly on intrinsic patterns and processes in pre-natal and post-natal brain maturation that anticipate psychosocial support in infancy. The operation of an intrinsic motive formation (IMF) that developed in the core of the brain before birth is evident in the tightly integrated intermodal sensory-motor coordination of a newborn infant's orienting to stimuli and preferential learning of human signals, by the temporal coherence and intrinsic rhythms of infant behaviour, especially in communication, and neonates' extraordinary capacities for reactive and evocative imitation. The correct functioning of this integrated neural motivating system is found to be essential to the development of both the infant's purposeful consciousness and his or her ability to cooperate with other persons' actions and interests, and to learn from them. The relevance of infants' inherent intersubjectivity to major child mental health issues is highlighted by examining selected areas of clinical concern. We review recent findings on postnatal depression, prematurity, autism, ADHD, specific language impairments, and central auditory processing deficits, and comment on the effcacy of interventions that aim to support intrinsic motives for intersubjective communication when these are not developing normally. [source] Adaptive Weighted Learning for Unbalanced Multicategory ClassificationBIOMETRICS, Issue 1 2009Xingye Qiao Summary In multicategory classification, standard techniques typically treat all classes equally. This treatment can be problematic when the dataset is unbalanced in the sense that certain classes have very small class proportions compared to others. The minority classes may be ignored or discounted during the classification process due to their small proportions. This can be a serious problem if those minority classes are important. In this article, we study the problem of unbalanced classification and propose new criteria to measure classification accuracy. Moreover, we propose three different weighted learning procedures, two one-step weighted procedures, as well as one adaptive weighted procedure. We demonstrate the advantages of the new procedures, using multicategory support vector machines, through simulated and real datasets. Our results indicate that the proposed methodology can handle unbalanced classification problems effectively. [source] Compulsive-like Behavior in Individuals with Down Syndrome: Its Relation to Mental Age Level, Adaptive and Maladaptive BehaviorCHILD DEVELOPMENT, Issue 2 2000David W. Evans This study examined the nature of repetitive, ritualistic, and compulsive-like behaviors in 50 typically developing children and 50 individuals with Down syndrome (DS), matched on mental age (MA; M = 59.72 months). Parents reported on their children's compulsive-like behaviors , including ritualistic habits , and perfectionistic behaviors, as well as their children's adaptive and maladaptive behaviors. Results indicated that children with DS show similar MA-related changes in compulsive-like behaviors compared to the MA-matched comparison group. Younger children (both typical and DS) exhibited significantly more compulsive-like behaviors than older children. In general, children with and without DS did not differ from each other in terms of the number of compulsive-like behaviors they engaged in, although participants with DS engaged in more frequent, more intense repetitive behaviors. Compulsive-like behaviors were differentially related to adaptive and maladaptive behaviors across the MA and mental retardation groups. The results extend the "similar sequence" model of development to the construct of compulsive-like behaviors, and also suggest that some repetitive behaviors may be among the behavioral phenotype of individuals with DS. [source] An improved study of real-time fluid simulation on GPUCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 3-4 2004Enhua Wu Abstract Taking advantage of the parallelism and programmability of GPU, we solve the fluid dynamics problem completely on GPU. Different from previous methods, the whole computation is accelerated in our method by packing the scalar and vector variables into four channels of texels. In order to be adaptive to the arbitrary boundary conditions, we group the grid nodes into different types according to their positions relative to obstacles and search the node that determines the value of the current node. Then we compute the texture coordinates offsets according to the type of the boundary condition of each node to determine the corresponding variables and achieve the interaction of flows with obstacles set freely by users. The test results prove the efficiency of our method and exhibit the potential of GPU for general-purpose computations. Copyright © 2004 John Wiley & Sons, Ltd. [source] Sparsely Precomputing The Light Transport Matrix for Real-Time RenderingCOMPUTER GRAPHICS FORUM, Issue 4 2010Fu-Chung Huang Precomputation-based methods have enabled real-time rendering with natural illumination, all-frequency shadows, and global illumination. However, a major bottleneck is the precomputation time, that can take hours to days. While the final real-time data structures are typically heavily compressed with clustered principal component analysis and/or wavelets, a full light transport matrix still needs to be precomputed for a synthetic scene, often by exhaustive sampling and raytracing. This is expensive and makes rapid prototyping of new scenes prohibitive. In this paper, we show that the precomputation can be made much more efficient by adaptive and sparse sampling of light transport. We first select a small subset of "dense vertices", where we sample the angular dimensions more completely (but still adaptively). The remaining "sparse vertices" require only a few angular samples, isolating features of the light transport. They can then be interpolated from nearby dense vertices using locally low rank approximations. We demonstrate sparse sampling and precomputation 5 × faster than previous methods. [source] Accelerating Ray Tracing using Constrained TetrahedralizationsCOMPUTER GRAPHICS FORUM, Issue 4 2008Ares Lagae Abstract In this paper we introduce the constrained tetrahedralization as a new acceleration structure for ray tracing. A constrained tetrahedralization of a scene is a tetrahedralization that respects the faces of the scene geometry. The closest intersection of a ray with a scene is found by traversing this tetrahedralization along the ray, one tetrahedron at a time. We show that constrained tetrahedralizations are a viable alternative to current acceleration structures, and that they have a number of unique properties that set them apart from other acceleration structures: constrained tetrahedralizations are not hierarchical yet adaptive; the complexity of traversing them is a function of local geometric complexity rather than global geometric complexity; constrained tetrahedralizations support deforming geometry without any effort; and they have the potential to unify several data structures currently used in global illumination. [source] Reputation-based semantic service discoveryCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 8 2006Ali Shaikh Ali Abstract An important component of Semantic Grid services is the support for dynamic service discovery. Dynamic service discovery requires the provision of rich and flexible metadata that is not supported by current registry services such as UDDI. We present a framework to facilitate reputation-based service selection in Semantic Grids. Our framework has two key features that distinguish it from other work in this area. First, we propose a dynamic, adaptive, and highly fault-tolerant reputation-aware service discovery algorithm. Second, we present a service-oriented distributed reputation assessment algorithm. In this paper, we describe the main components of our framework and report on our experience of developing the prototype. Copyright © 2005 John Wiley & Sons, Ltd. [source] Full waveform seismic inversion using a distributed system of computersCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 11 2005Indrajit G. Roy Abstract The aim of seismic waveform inversion is to estimate the elastic properties of the Earth's subsurface layers from recordings of seismic waveform data. This is usually accomplished by using constrained optimization often based on very simplistic assumptions. Full waveform inversion uses a more accurate wave propagation model but is extremely difficult to use for routine analysis and interpretation. This is because computational difficulties arise due to: (1) strong nonlinearity of the inverse problem; (2) extreme ill-posedness; and (3) large dimensions of data and model spaces. We show that some of these difficulties can be overcome by using: (1) an improved forward problem solver and efficient technique to generate sensitivity matrix; (2) an iteration adaptive regularized truncated Gauss,Newton technique; (3) an efficient technique for matrix,matrix and matrix,vector multiplication; and (4) a parallel programming implementation with a distributed system of processors. We use a message-passing interface in the parallel programming environment. We present inversion results for synthetic and field data, and a performance analysis of our parallel implementation. Copyright © 2005 John Wiley & Sons, Ltd. [source] Threatened Peripheral Populations in Context: Geographical Variation in Population Frequency and Size and Sexual Reproduction in a Clonal Woody ShrubCONSERVATION BIOLOGY, Issue 3 2007SARAH B. YAKIMOWSKI especies en riesgo; límites de distribución; poblaciones periféricas; reproducción sexual; Vaccinium stamineum Abstract:,Geographically peripheral populations of widespread species are often the focus of conservation because they are locally rare within political jurisdictions. Yet the ecology and genetics of these populations are rarely evaluated in a broader geographic context. Most expectations concerning the ecology and evolution of peripheral populations derive from the abundant-center model, which predicts that peripheral populations should be less frequent, smaller, less dense, and have a lower reproductive rate than central populations. We tested these predictions and in doing so evaluated the conservation value of peripheral populations for the clonal shrub Vaccinium stamineum L. (Ericaceae, deerberry), which is listed as threatened in Canada. Based on 51 populations sampled from the center to the northern range limits over 2 years, population frequency and size declined toward the range limit, but ramet density increased. Sexual reproductive output varied widely among populations and between years, with many populations producing very few seeds, but did not decline toward range margins. In fact seed mass increased steadily toward range limit, and this was associated with faster germination and seedling growth, which may be adaptive in seasonal northern environments. Our results did not support the prediction that clonal reproduction is more prevalent in peripheral populations or that it contributed antagonistically to the wide variation in seed production. Peripheral populations of V. stamineum are as productive as central populations and may be locally adapted to northern environments. This emphasizes the importance of a broad geographical perspective for evaluating the ecology, evolution, and conservation of peripheral populations. Resumen:,Las poblaciones geográficamente periféricas de una especie de amplia distribución a menudo son el foco de conservación porque son raras localmente dentro de jurisdicciones políticas. Sin embargo, la ecología y genética de estas poblaciones son evaluadas poco frecuentemente en un contexto geográfico más amplio. La mayoría de las expectaciones relacionadas con la ecología y evolución de las poblaciones periféricas se derivan del modelo centro-abundante, que predice que las poblaciones periféricas son menos frecuentes, más pequeñas, menos densas y menor tasa reproductiva que poblaciones centrales. Probamos estas predicciones y al hacerlo evaluamos el valor de conservación de poblaciones periféricas de una especie de arbusto clonal (Vaccinium stamineum L., Ericaceae), que está enlistada como amenazada en Canadá. Con base en 51 poblaciones muestreadas del centro hacia los límites norteños de su distribución durante 2 años, la frecuencia y tamaño poblacional declinó hacia los límites de su distribución, pero la densidad de rametos aumentó. La reproducción sexual varió ampliamente entre las poblaciones y entre años, con muchas poblaciones produciendo muy pocas semillas, pero no declinó hacia los límites de su distribución. De hecho, la masa de semillas incrementó sostenidamente hacia los límites, y esto se asoció a una acelerada germinación y crecimiento de plántulas, lo cual puede ser adaptativo en ambientes norteños estacionales. Nuestros resultados no sustentaron la predicción de que la reproducción clonal es más prevaleciente en poblaciones periféricas o que contribuye antagónicamente a la amplia variación en la producción de semillas. Las poblaciones periféricas de V. stamineum son tan productivas como las poblaciones centrales y pueden estar adaptadas localmente a ambientes norteños. Esto enfatiza la importancia de una perspectiva geográfica amplia cuando se evalúa la ecología, evolución y conservación de poblaciones periféricas. [source] Conceptual background, development, and preliminary data from the unified protocol for transdiagnostic treatment of emotional disorders,DEPRESSION AND ANXIETY, Issue 10 2010Zofia A. Wilamowska M.A. Abstract Anxiety and mood disorders are common, chronic, costly, and characterized by high comorbidity. The development of cognitive behavioral approaches to treating anxiety and mood disorders has left us with highly efficacious treatments that are increasingly widely accepted. The proliferation of treatment manuals targeting single disorders, sometimes with trivial differences among them, leaves the mental health professional with no clear way to choose one manual over another and little chance of ever becoming familiar with most of them, let alone trained to competence in their delivery. Deepening understanding of the nature of emotional disorders reveals that commonalities in etiology and latent structures among these disorders supersedes differences. Based on empirical evidence from the domains of learning, emotional development and regulation, and cognitive science, we have distilled a set of psychological procedures that comprise a unified intervention for emotional disorders. The Unified Protocol (UP) is a transdiagnostic, emotion-focused cognitive behavioral treatment, which emphasizes the adaptive, functional nature of emotions, and seeks to identify and correct maladaptive attempts to regulate emotional experiences, thereby facilitating appropriate processing and extinction of excessive emotional responding to both internal (somatic) and external cues. The treatment components of the UP are briefly outlined. Theory and rationale supporting this new approach are described along with some preliminary evidence supporting its efficacy. Implications for the treatment of emotional disorders using the UP are discussed. Depression and Anxiety, 2010. © 2010 Wiley-Liss, Inc. [source] Something old, something new: a developmental transition from familiarity to novelty preferences with hidden objectsDEVELOPMENTAL SCIENCE, Issue 2 2010Jeanne L. Shinskey Novelty seeking is viewed as adaptive, and novelty preferences in infancy predict cognitive performance into adulthood. Yet 7-month-olds prefer familiar stimuli to novel ones when searching for hidden objects, in contrast to their strong novelty preferences with visible objects (Shinskey & Munakata, 2005). According to a graded representations perspective on object knowledge, infants gradually develop stronger object representations through experience, such that representations of familiar objects can be better maintained, supporting greater search than with novel objects. Object representations should strengthen with further development to allow older infants to shift from familiarity to novelty preferences with hidden objects. The current study tested this prediction by presenting 24 11-month-olds with novel and familiar objects that were sometimes visible and sometimes hidden. Unlike 7-month-olds, 11-month-olds showed novelty preferences with both visible and hidden objects. This developmental shift from familiarity to novelty preference with hidden objects parallels one that infants show months earlier with perceptible stimuli, but the two transitions may reflect different underlying mechanisms. The current findings suggest both change and continuity in the adaptive development of object representations and associated cognitive processes. [source] Adaptive training leads to sustained enhancement of poor working memory in childrenDEVELOPMENTAL SCIENCE, Issue 4 2009Joni Holmes Working memory plays a crucial role in supporting learning, with poor progress in reading and mathematics characterizing children with low memory skills. This study investigated whether these problems can be overcome by a training program designed to boost working memory. Children with low working memory skills were assessed on measures of working memory, IQ and academic attainment before and after training on either adaptive or non-adaptive versions of the program. Adaptive training that taxed working memory to its limits was associated with substantial and sustained gains in working memory, with age-appropriate levels achieved by the majority of children. Mathematical ability also improved significantly 6 months following adaptive training. These findings indicate that common impairments in working memory and associated learning difficulties may be overcome with this behavioral treatment. [source] The 2004 Madrid train bombings: an analysis of pre-hospital managementDISASTERS, Issue 1 2008Alejandro López Carresi The terrorist train bombings in Madrid, Spain, on 11 March 2004 triggered a swift and massive medical response., This paper analyses the pre-hospital response to the attacks to gain insight into current trends in disaster management among Madrid's Emergency Medical Services (EMSs). To this end, the existing emergency planning framework is described, the basic structures of the different EMSs are presented, and the attacks are briefly depicted before consideration is given to pre-hospital management. Finally, an explanation of the main underlying misconceptions in emergency planning and management in Madrid is provided to aid understanding of the origins of some of the problems detected during the response. These are attributable mainly to inappropriate planning rather than to mistakes in field-level decision-making. By contrast, many of the successes are attributable to individual initiatives by frontline medics who compensated for the lack of clear command by senior managers by making adaptive and flexible decisions. [source] The origin of higher taxa: macroevolutionary processes, and the case of the mammalsACTA ZOOLOGICA, Issue 1 2007T. S. Kemp Abstract The origin of a new higher taxon is characterized by a long-term phylogenetic trend, involving evolutionary changes in a large number of characters. At this phylogenetic level, the conflict between internal integration of the phenotype and its evolvability can be resolved by the correlated progression model, in which many disparate traits evolve by a sequence of small increments in loose correlation with one another, rather than by the modularity model. The trend leading to the new higher taxon implies the existence of a long ridge in an adaptive landscape. An evolutionary lineage tracking it requires adaptive changes in broad biological characteristics, involving many traits. Species selection is a possible additional driver of the trend. These conclusions are tested against the synapsid fossil record of the origin of mammals. The reconstructed sequence of acquisition of mammalian traits supports the correlated progression model. The adaptive ridge involved is postulated to have been a sequence of overlapping niches requiring increasing ability to remain active in daily and seasonally fluctuating environments by means of increasing internal regulation. An inferred speciation bias in favour of relatively small, relatively more progressive carnivores indicates that species selection was also involved in driving the trend. Palaeoenvironmental evidence indicates that ecological opportunity probably played a role at certain points along the lineage. [source] A simple LMS-based approach to the structural health monitoring benchmark problemEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2005J. Geoffrey Chase Abstract A structure's health or level of damage can be monitored by identifying changes in structural or modal parameters. However, the fundamental modal frequencies can sometimes be less sensitive to (localized) damage in large civil structures, although there are developing algorithms that seek to reduce this difficulty. This research directly identifies changes in structural stiffness due to modeling error or damage using a structural health monitoring method based on adaptive least mean square (LMS) filtering theory. The focus is on computational simplicity to enable real-time implementation. Several adaptive LMS filtering based approaches are used to analyze the data from the IASC,ASCE Structural Health Monitoring Task Group Benchmark problem. Results are compared with those from the task group and other published results. The proposed methods are shown to be very effective, accurately identifying damage to within 1%, with convergence times of 0.4,13.0 s for the twelve different 4 and 12 degree of freedom benchmark problems. The resulting modal parameters match to within 1% those from the benchmark problem definition. Finally, the methods developed require 1.4,14.0 Mcycles of computation and therefore could easily be implemented in real time. Copyright © 2004 John Wiley & Sons, Ltd. [source] Identification of soil degradation during earthquake excitations by Bayesian inferenceEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 6 2003Jianye Ching Abstract A Bayesian inference approach is introduced to identify soil degradation behaviours at four downhole array sites. The approach of inference is based on a parametric time-varying infinite impulse response filter model. The approach is shown to be adaptive to the changes of filter parameters and noise amplitudes. Four sites, including the Lotung (Taiwan), Chiba (Japan), Garner Valley (California), and Treasure Island (California) sites with downhole seismic arrays are analysed. Our results show two major types of soil degradation behaviour: the well-known strain-dependent softening, and reduction in stiffness that is not instantaneously recoverable. It is also found that both types of soil degradation are more pronounced in sandy soils than in clayey soils. The mechanism for the second type of soil degradation is not yet clear to the authors and suggested to be further studied. Copyright © 2003 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||