For the safe and economical construction of embankment dams, the mechanical behaviour of the rockfill materials used in the dam’s shell must be analyzed. The characterization of rockfill materials with specified shear strength is difficult and expensive due to the presence of particles greater than 500 mm in diameter. This work investigates the feasibility of using an extreme gradient boosting computing paradigm to estimate the shear strength of rockfill materials. To train and validate the proposed XGBoost model, a total of (...) 165 databases obtained from the literature are chosen. The XGBoost model was compared against support vector machine, adaptive boosting, random forest, and K-nearest neighbor models described in the literature. XGBoost beats SVM, RF, AdaBoost, and KNN models in terms of performance evaluation metrics such as coefficient of determination, Nash–Sutcliffe coefficient, and error in the root mean square ratio to the standard deviation of the measured data. The results demonstrated that the XGBoost model has the highest prediction performance with, followed by the SVM model with, RF, the AdaBoost model with and the KNN model with. A sensitivity analysis has been conducted to ascertain the impact of each investigated input parameter. This study demonstrates that the established XGBoost model for estimating the shear strength of rockfill materials is reliable. (shrink)

The concept of wild food does not play a significant role in contemporary nutritional science and it is seldom regarded as a salient feature within standard dietary guidelines. The knowledge systems of wild edible taxa are indeed at risk of disappearing. However, recent scholarship in ethnobotany, field biology, and philosophy demonstrated the crucial role of wild foods for food biodiversity and food security. The knowledge of how to use and consume wild foods is not only a means to deliver high-end (...) culinary offerings, but also a way to foster alternative models of consumption. Our aim in this paper is to provide a conceptual framework for wild foods, which can account for diversified wild food ontologies. In the first section of the paper, we survey the main conception of wild foods provided in the literature, what we call the Nature View. We argue that this view falls short of capturing characteristics that are core to a sound account of wilderness in a culinary sense. In the second part of the paper, we provide the foundation for an improved model of wild food, which can countenance multiple dimensions and degrees connoting wilderness in the culinary world. In the third part of the paper we argue that thanks to a more nuanced ontological analysis, the gradient framework can serve ethnobiologists, philosophers, scientists, and policymakers to represent and negotiate theoretical conflicts on the nature of wild food. (shrink)

The two parameters of leaf dimension namely, length and width, show inverse correlation with the third parameter, the thickness. A thermal diffusion model is proposed which explains the inverse relationship between these and envisages that while leaf length and width are directly influenced by the microclimate the thickness is affected by the microclimate through endoclimate and energy balance in the leaves. The significance of the model is discussed in the light of its importance in assessing the survival range of plant (...) species along the altitudinal gradient. (shrink)

Recent decades have witnessed the rapid evolution of robotic applications and their expansion into a variety of spheres with remarkable achievements. This article researches a crucial technique of robot manipulators referred to as visual servoing, which relies on the visual feedback to respond to the external information. In this regard, the visual servoing issue is tactfully transformed into a quadratic programming problem with equality and inequality constraints. Differing from the traditional methods, a gradient-based recurrent neural network for solving the visual (...) servoing issue is newly proposed in this article in the light of the gradient descent method. Then, the stability proof is presented in theory with the pixel error convergent exponentially to zero. Specifically speaking, the proposed method is able to impel the manipulator to approach the desired static point while maintaining physical constraints considered. After that, the feasibility and superiority of the proposed GRNN are verified by simulative experiments. Significantly, the proposed visual servo method can be leveraged to medical robots and rehabilitation robots to further assist doctors in treating patients remotely. (shrink)

It is not yet clear which response behavior requires self-regulatory effort in the moral dilemma task. Previous research has proposed that utilitarian responses require cognitive control, but subsequent studies have found inconsistencies with the empirical predictions of that hypothesis. In this paper we treat participants’ sensitivity to utilitarian gradients as a measure of performance. We confronted participants (N = 82) with a set of five dilemmas evoking a gradient of mean utilitarian responses in a 4-point scale and collected data (...) on heart rate variability and on utilitarian responses. We found positive correlations between tonic and phasic HRV and sensitivity to the utilitarian gradient in the high tonic group, but not in the low tonic group. Moreover, the low tonic group misplaced a scenario with a selfish incentive at the high end of the gradient. Results suggest that performance is represented by sensitivity correlated with HRV and accompanied with a reasonable placement of individual scenarios within the gradient. (shrink)

Mental representations have continuous as well as discrete, combinatorial properties. For example, while predominantly discrete, phonological representations also vary continuously; this is reflected by gradient effects in instrumental studies of speech production. Can an integrated theoretical framework address both aspects of structure? The framework we introduce here, Gradient Symbol Processing, characterizes the emergence of grammatical macrostructure from the Parallel Distributed Processing microstructure (McClelland, Rumelhart, & The PDP Research Group, 1986) of language processing. The mental representations that emerge, Distributed Symbol Systems, (...) have both combinatorial and gradient structure. They are processed through Subsymbolic Optimization–Quantization, in which an optimization process favoring representations that satisfy well-formedness constraints operates in parallel with a distributed quantization process favoring discrete symbolic structures. We apply a particular instantiation of this framework, λ-Diffusion Theory, to phonological production. Simulations of the resulting model suggest that Gradient Symbol Processing offers a way to unify accounts of grammatical competence with both discrete and continuous patterns in language performance. (shrink)

Major contributions emanating from Sagvolden et al.'s theory include elucidation of the role in attention-deficit/hyperactivity disorder (ADHD) of temporal information processing, social learning, and response extinction learning. Key issues include a need for clearer explanation of the relative role of impulsivity versus response suppression/inhibition in the dual process model, and delineation of genotype-environment correlations versus interactions in the social and experiential mechanisms posited.

In biology, the “field” concept is used in different ways. Therefore, its meaning in biology as compared to that in physics, and the relation between the conceptions of “gradient” and “field” are studied.In physics, scalar fields, vector fields and tensor fields are distinguished. In a scalar field, the variation of the scalar in space is expressed in form of a gradient. For the whole of a scalar field with its derived gradients the term “gradient-field” may be used.In biology, especially (...) in experimental embryology, the field concept is used both in a purely descriptive sense and as a means of causal analysis. To the first group belong the kinematic fields and growth fields. The kinematic field is a vector field; the growth field is generally a tensor field, but may be treated as a gradient-field in the most simple cases. In the causal analysis of development the gradient-field plays an important part, in the form of axial, superficial and spatial gradient-fields. In such a field by the combined action of the scalar and the gradients a great diversity of relations may occur. Probably, both the induction field and the organisation field belong to the class of gradient-fields. (shrink)

In biology, the “field” concept is used in different ways. Therefore, its meaning in biology as compared to that in physics, and the relation between the conceptions of “gradient” and “field” are studied.In physics, scalar fields, vector fields and tensor fields are distinguished. In a scalar field, the variation of the scalar in space is expressed in form of a gradient. For the whole of a scalar field with its derived gradients the term “gradient-field” may be used.In biology, especially (...) in experimental embryology, the field concept is used both in a purely descriptive sense and as a means of causal analysis. To the first group belong the kinematic fields and growth fields. The kinematic field is a vector field; the growth field is generally a tensor field, but may be treated as a gradient-field in the most simple cases. In the causal analysis of development the gradient-field plays an important part, in the form of axial, superficial and spatial gradient-fields. In such a field by the combined action of the scalar and the gradients a great diversity of relations may occur. Probably, both the induction field and the organisation field belong to the class of gradient-fields.Der Feldbegriff wird in der Biologie in sehr verschiedener Weise verwendet. Es wird daher versucht, das Wesen der „biologischen Felder” in Anlehnung an die Physik zu bestimmen, und das Verhältnis zwischen den Begriffen „Gradient” und „Feld” darzustellen.In der Physik unterscheidet man Skalarfelder, Vektorfelder und Tensorfelder. Im Skalarfeld lässt sich der Wechsel der Skalargrösse im Raume durch einen Gradienten darstellen. Für die Gesamtheit eines Skalarfeldes mit seinen abgeleiteten Gradienten wird der Ausdruck „Gradientfeld” vorgeschlagen.In der Biologie, im besonderen in der Entwicklungsmechanik, wird der Feldbegriff bald in rein-beschreibendem Sinne, bald als Mittel zur kausalen Analyse verwendet. Zur ersten Gruppe gehören das Bewegungsfeld und das Wachstumsfeld. Das Bewegungsfeld ist ein Vektorfeld; das Wachstumsfeld ist im allgemeinen ein Tensorfeld, kann aber im einfachsten Falle als ein Gradientfeld betrachtet werden. In der kausalen Analyse der Entwicklungserscheinungen spielt besonders das Gradientfeld eine grosse Rolle; dabei kann es sich um ein axiales, oberflächliches oder räumliches Gradientfeld handeln. Es wird darauf hingewiesen, dass in einem Gradientfelde durch das Zusammenwirken der Skalargrösse und des Gradienten eine grosse Mannigfaltigkeit der Beziehungen auftreten kann. Auch das Induktionsfeld und das Organisationsfeld gehören vermutlich zu den Gradientfeldern. (shrink)

There is increasing evidence for directional guidance of growing axons by molecular gradients in target tissues. Aside from biochemical studies on gradients and their role, the capability of axons to approach their target position from different aspects of a two-dimensional field is itself an indication for guidance by gradients. According to this criterion, such guidance is expected to be involved not only in map-formation in the visual system but also in targeting of receptor cell axons in the (...) olfactory bulb. In this paper, physico-chemical concepts of visual mapping are adapted to olfactory targeting. In both cases there must be sophisticated processing of graded cues in the growing tip of the axon for growth cone navigation. In visual map formation, a target position is determined by influences of cues depending on the position of axonal origin; in olfactory targeting, however, these influences are expected to be based on properties of the receptor-cell-specific molecules (possibly including the receptor molecule itself), as well as by gene regulation affecting the levels of expression. According to this concept, the main role of molecules expressed in a receptor-cell-type specific manner is not matching specific counterparts on the target tissue, but instead quantitative modulation of growth cone steering for sensing the direction towards the target position. (shrink)

Gap genes stand at the top of the zygotic segmentation hierarchy in Drosophila. Their expression domains are set up by a combination of maternal regulatory signals and interactions among themselves. In addition, these regulatory pathways are partially redundantly specified by the maternal and zygotic genomes, or by multiple zygotic gene products. The gap genes code for transcription factors which exert their function by foming short‐range morphogenetic gradients; differential concentrations of these transcription factors can either act as activators or as (...) repressors for the expression domains of neighbouring genes. It is possible to view the gap genes as a system of genes that subdivides the embryo by forming an activation‐repression cascade proceeding from anterior towards posterior. (shrink)