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The concept of extended slash distribution is introduced. For the extended slash distribution of the sum of two independent logistic random variables, the characteristic function, moments, absolute...

Learning to program is the new literacy of the 21st century. Computational thinking, closely related to programming, requires thinking and solving problems with different levels of abstraction and is independent of hardware devices. The early childhood education stage provides teachers with the opportunity to lay the foundations for a comprehensive quality education using innovative tools and technologies. Educational robotics in early childhood education becomes a tool that facilitates the acquisition of knowledge to children, playfully, based on the principles of interactivity, social interrelationships, collaborative work, creativity, constructivist and constructionist learning, and a student-centered didactic approach, allowing in turn that student can acquire digital competencies and develop logical and computational thinking in an underlying way. This project explores the current state of teaching and learning computational thinking and programming in early childhood education in an inclusive manner. Moreover, the lack of diversity and inequality is particularly latent in science, Technology, Engineering, and Mathematics (STEM) fields. Therefore, this work considers this problem and presents an inclusive coeducation approach to this new literacy, eliminating gender stereotypes and extending them to people with Down syndrome and hospitalized minors.

We consider the random variables Zi=βi2Yi/∑k=1mβk2Yk where Yi,i=1…,m are independent inverted chi-square r.v. with νi degrees of freedom. The probability density function of Z=(Z1,Z2,…Zm) is obtain...

Three new models for the flow–density relationship are proposed in this work. The resulting flow–density curves are concave in the whole range of feasible values for the parameters. These models have four parameters, three of them being the jam density, the free-flow speed and the kinematic wave speed. The fourth parameter is a shape parameter. The models allow for a great flexibility for fitting of real traffic flow and density data. A remarkable property of these models is the fact that they yield a bilinear fundamental diagram when the shape parameter tends to infinity. The models have been tested with freeway data and urban data. The results demonstrate that the models achieve an excellent goodness of fit and yield realistic estimates of the parameters. The models proposed in this work are a valuable tool not only for fitting flow–density data but also for its use in traffic flow dynamic models.

Traffic volume is a parameter used to quantify demand in transportation studies, and it is commonly collected by using on-road (fixed) sensors such as inductive loops, cameras, etc. The installation of fixed sensors to cover all roads is neither practical nor economically feasible; therefore, they are only installed on a subset of links. Cellular phone tracking has been an emerging topic developed and investigated during the last few years to extract traffic information. Cellular systems provide alternative methods to detect phones in motion without the cost and coverage limitations associated with those infrastructure-based solutions. Utilizing existing cellular systems to capture traffic volume has a major advantage compared with other solutions, since it avoids new and expensive hardware installations of sensors, with a large number of cellular phones acting as probes. This paper proposes a set of models for inferring the number of vehicles moving from one cell to another by means of anonymous call data of phones. The models contain, in their functional form, terms related to the users' calling behavior and other characteristics of the phenomenon such as hourly intensity in calls and vehicles. A set of intercell boundaries with different traffic background and characteristics were selected for the field test. The experiment results show that reasonable estimates are achieved by comparison with volume measurements collected by detectors located in the same study area. The motion of phones while being involved in calls can be used as an easily accessible, fast, and low-cost alternative to deriving volume data on intercell boundaries.

Some recent developments in path generation have been based on neural network mechanism databases, which instantaneously provide an approximate solution of the synthesis problem. We describe a way to reduce the design space, ensuring that the neural network always yields a consistent crank-rocker mechanism with optimal transmission angle. Moreover, instead of the usual strategy of using Fourier coefficients, we propose a new method based on wavelet descriptors to represent the shape of the path, where the points do not need to be sampled at a constant time interval. Numerical results demonstrate the superiority of this wavelet-based neural network over the Fourier-based network in finding the optimal mechanism. They also show the accuracy of the proposed approach in providing near optimal crank-rocker mechanism solutions for path generation.

International audience; Intercontinental introductions are widespread in the genus Spartina, with important ecological and evolutionary consequences. The native or introduced status of Spartina species is then critical with regard to biodiversity assessment, especially for vulnerable Mediterranean coastline ecosystems. Spartina versicolor was first recorded in southern France in 1849, then successively in various places on the European and North-African Mediterranean and Atlantic coasts. This species is considered to be either a European native or an invasive species introduced from North America which has a high morphological similarity to the Atlantic American species Spartina patens. We performed extensive sampling of S. versicolor in Europe and North Africa (from natural populations and herbarium collections) and compared these samples to other European and American Spartina species (including S. patens). Chromosome counts were reported for the first time and revealed that S. versicolor is tetraploid (2n = 4x = 40). Phylogenetic analyses based on chloroplast and nuclear ribosomal DNA sequences did not reveal any molecular variation within S. versicolor. In this species, a single haplotype, that is identical to one haplotype of S. patens, was found in the four chloroplast and the nuclear ribosomal ITS regions investigated. In addition, simple sequence repeat markers were used and revealed a low level of genetic diversity within S. versicolor, suggesting that the introduction of S. versicolor occurred from a narrow genetic pool of S. patens from North Americ

Background: The aim of this study is to confirm whether the absolute and relative lengths of the first metatarso-digital segment is greater than normal in incipient hallux limitus deformity. Methods: In a sample of 144 dorsoplantar radiographs under weightbearing conditions (94 of normal feet and 50 of feet with a slightly stiff hallux), measurements were made of the relative first metatarsal protrusion, the length and width of the first metatarsal and of the proximal phalanx of the hallux, the length of the distal phalanx of the hallux, and the total length of the hallux. Results: There were significant differences between the two types of feet in the relative first metatarsal protrusion, the width of the first metatarsal, the length and width of the proximal phalanx of the hallux, the length of the distal phalanx, and the total length of the hallux. Conclusion: The size of the first metatarso-digital segment could be implicated in the development of hallux limitus deformity. (J Am Podiatr Med Assoc 97(6): 460–468, 2007)

A procedure for the enumeration of the graphs of 1-dof planetary gear trains is presented. The planetary gear trains enumerated have a single input shaft and a single output shaft. These gear trains should satisfy certain functional constraints that avoid the existence of idle links. These constraints are derived. The enumeration of the graphs exploits the resulting particular features of the structure of planetary gear trains by proceeding gradually through different levels of that structure. The procedure includes a check for isomorphism among the resulting graphs. Finally, the graphs of the planetary gear trains having up to 9 links are presented. Those graphs containing embedded structures are identified.

Two procedures are presented for obtaining the analytical expression for the efficiency of any planetary gear train. The first employs the speed and torque equations and the concept of virtual gear teeth ratios. The second is based on an relationship between the gearing power and the speed ratio. This relationship, which is satisfied by any spur gear train, allows one to obtain the efficiency expression in a surprisingly simple manner. Two proofs of that relationship are presented.

A model of the evolution of speed perturbations in dense traffic flow is presented in this work. Traffic volume is assumed to be at capacity and a given vehicle undergoes a temporary speed drop. This speed drop may propagate through the traffic flow until it is either dissipated or causes the stoppage of the traffic flow. The two events are random and occur with a certain probability. The proposed model leads to a set of recurrence equations for the speed drop and its duration. The simulation of those equations allows the estimation of the normalization probability, that is, the probability that the perturbation vanishes. An analytical approximation for the normalization probability is also proposed. The approximation is based on a result from Brownian motion theory. The agreement with the simulation results is fairly good given the simplicity of the approximation. The model and its analytical approximation allows one to conjecture which could be the most important parameters that determine the evolution of the perturbation. The implications of this conjecture are commented and the assumptions of the model are contrasted with related work.

This paper presents a simple physical principle that can be used to solve the kinematic wave problem for freeways with special lanes and priority vehicles. The principle is shown to yield the flows for all possible ‘Riemann problems’ arising in a homogeneous highway, so that its application in a simulation is equivalent to the Godunov ‘classic’ finite difference approximation method. The principle is appealing because its physical basis, unlike purely mathematical formulae, suggests a natural way in which boundary conditions for practical problems may be treated. Perhaps the IT principle will prove useful for solving general problems, e.g. involving multicommodity networks. This issue deserves more study. As an illustration of this potential the paper shows that an IT simulation of the finite highway problem solved in the companion paper (Daganzo, Transportation Research B , 31 , 83–102, 1997) matches rather well the exact solution. Additional tests using other boundary conditions for the same problem also revealed a good match.

Technical and economic investigations of automated highway systems (AHS) are addressed. It has generally been accepted that such systems show potential to alleviate urban traffic congestion, so most of the AHS research has been focused instead on technical design and implementation issues. It is demonstrated that, despite making a number of assumptions that are favorable to AHS, the actual viable implementation opportunities for AHS are scarce, and that most existing congested urban areas can be disqualified on the basis of at least one criterion developed herein. Technical investigations are described, including realistic estimates of AHS capacity, interfacing with the local street system, and storage issues. Discussion then turns to identifying criteria to help establish the types of urban areas that might be likely candidates for AHS technology. These criteria relate to the nature of the surrounding infrastructure and the traffic demands placed on it, as well as the economic realities of AHS implementation. Certain “boutique” locations where AHS might be beneficial are identified, but it is uncertain whether enough benefit could be realized to make AHS palatable to the general public. AHS technology is not dismissed, but the simple analyses contained herein should warn that much more research into these areas is required before fully informed decision making about the future of AHS technologies can be accomplished.

The study of four-bar linkages to trace a desired path is an important part of teaching in mechanical design. When the number of precision points exceeds a certain number, most recent approaches utilize intelligent optimization methods based on too complex computer science theories to be implemented by an engineering student. In this article we develop and implement new mechanism design results, reducing simultaneously the design space to facilitate finding the optimal mechanism. Finally, we apply global optimization methods that do not require analytical expression of the objective function and are freely available for educational use with Matlab. The proposed computerized methodology focuses student motivation on the mechanical aspects of the problem. Design examples presented illustrate the effectiveness of the approach that provides a solution quality comparable to that of the recently proposed intelligent optimization methods with simplicity of implementation and fast convergence. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 87–92, 2010; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20181

The use of the Hodrick-Prescott (HP) filter is presented as an alternative to the traditional digital filtering and spline smoothing methods currently used in biomechanics. In econometrics, HP filtering is a standard tool used to decompose a macroeconomic time series into a nonstationary trend component and a stationary residual component. The use of the HP filter in the present work is based on reasonable assumptions about the jerk and noise components of the raw displacement signal. Its applicability was tested on 4 kinematic signals with different characteristics. Two are well known signals taken from the literature on biomechanical signal filtering, and the other two were acquired with our own motion capture system. The criterion for the selection of cutoff frequency was based on the power spectral density of the raw displacement signals. The results showed the technique to be well suited to filtering biomechanical displacement signals in order to obtain accurate higher derivatives in a simple and systematic way. Namely, the HP filter and the generalized cross-validated quintic spline (GCVSPL) produce similar RMS errors on the first (0.1063 vs. 0.1024 m/s2) and second (23.76 vs. 23.24 rad/s2) signals. The HP filter performs slightly better than GCVSPL on the third (0.209 vs. 0.236 m/s2) and fourth (1.596 vs. 2.315 m/s2) signals.

In biomechanics studies it is necessary to obtain acceleration of certain parts of the body in order to perform dynamical analysis. The motion capture systems introduce systematic measurement errors that appear in the form of high-frequency noise in recorded displacement signals. The noise is dramatically amplified when differentiating displacements to obtain velocities and accelerations. To avoid this phenomenon it is necessary to smooth the displacement signal prior to differentiation. The use of Singular Spectrum Analysis (SSA) is presented in this paper as an alternative to traditional digital filtering methods. SSA decomposes original time series into a number of additive time series each of which can be easily identified as being part of the modulated signal, or as being part of the random noise. An automatic filtering procedure based in SSA is presented in this work. The procedure is applied to two signals to demonstrate its performance.

Introduction: In the right ventricle (RV), unlike the left ventricle (LV), there is a predominance of longitudinal fibers that are necessary to empty systolic volume against the low pulmonary resistance. The normal longitudinal strain of the RV is -30 to -35% and transversal (radial) strain 20 to 25%. As pulmonary artery hypertension (PAH) develops RV dysfunction, systolic tricuspid regurgitation may be inadequate to estimate the pulmonary pressure.The pulmonary flow acceleration time, TAPSE and tissue Doppler of the tricuspid annulus may infer, but not quantify RV function. Objectives: The aim of this work is to assess with speckle tracking RV strain in patients with PAH and compare the results with data obtained in normal subjects. Methods: Assess RV function parameters (fractional areas, TAPSE and tricuspid regurgitation gradient). Determine longitudinal and transverse strain from the apical view in septum and free wall in patients with PAH and in healthy subjects. Material: 30 PAH patients, mean age 56+/-11 years, 21 male. Results: Among PAH patients and normal subjects, fractional areas were 22% and 46% and TAPSE 1.6 and 2.5 cm. Tricuspid regurgitation gradient was 57 and 19 mmHg. Longitudinal strain -14% and -29% and transverse strain 37% and 22% respectively. Conclusion: Patients with PAH modify the pattern of myocardial strain, with high transversal deformation, probably due to the RV adaptation to the high pressure.Conventional parameters to assess RV function may be masked by the systolic dysfunction of this camera. Disclosure of Interest: None Declared

Background: Orthotic devices are used to help children progressively acquire a more physiologic walking pattern. Methods: To determine the effect of an orthotic device with an out-toeing wedge along with a physiologic shoe as treatment for in-toed gait, angle of gait was measured in 48 children aged 3 to 14 years with in-toed gait. The following comparisons were made: angle of gait in children unshod versus children shod without treatment, angle of gait in children shod without treatment versus children shod plus orthoses, and angle of gait in children unshod versus children shod plus orthoses. Results: Using a correctly fitting shoe increased the angle of gait in a nonsignificant manner, but a significant increase was revealed in the comparison of the angle of gait in children unshod versus children under treatment. The results showed that the behavior in boys and girls was similar to that in the total sample. Regarding side, the corrective effect of the orthotic device was similar in the two feet. However, the data showed a greater corrective effect of the shoe in the right foot. Conclusions: Orthotic devices with out-toeing wedge combined with correctly fitting shoes, as well as shoes alone, are useful tools in the treatment of in-toed gait in children. (J Am Podiatr Med Assoc 100(6): 472–478, 2010)