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Los linfangiomas abdominales son tumores quísticos poco frecuentes en pediatría, representan el 1% de todos los casos de linfangiomas; los síntomas clínicos no son específicos, se descubren de forma incidental; actualmente el manejo quirúrgico es de primera elección, pero se deben valorar otras posibilidades terapéuticas como los agentes esclerosantes que, dependiendo del tamaño, la ausencia o no de sintomatología y las comorbilidades del paciente se convierte en otra opción terapéutica menos invasivo con el cual se logran buenos resultados; se describe los casos clínicos de dos neonatos con diagnóstico de linfangioma retroperitoneal, manejados con agentes esclerosantes (caso 1) y cirugía (caso 2), mostrando las diferentes opciones terapéuticas. Recibido: 31/12/2020 Aceptado:17/02/2021 Conflicto de interés: Los autores declaran no poseer conflicto de interés

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...

(1) Background: A decrease in operative time can not only improve patient outcomes through a reduction in the risk of developing complications but can also result in cost savings. The aim of this study is to determine whether there an intraoperative time gain can be achieved by using the preoperative virtual planning of mandibular reconstruction using a free fibula flap compared with freehand plate bending and osteotomies. (2) Methods: A retrospective comparative study was carried out in the Oral and Maxillofacial Department of La Paz University Hospital, Madrid, Spain. The study compared 18 patients in the CAD/CAM group with 19 patients in the conventional freehand group. A comparison was made between the total surgical time, the comorbidities, and the hospital stay. The resource consumption was estimated using a cost analysis. (3) Results: Although CAD/CAM was a statistically more expensive procedure in the perioperative phase, no significant differences were observed in total health care costs between the two groups. There was a non-significant trend towards an increase in complications with conventional reconstruction plates compared to patient-specific plates (PSI). (4) Conclusions: CAD/CAM technology and a 3D printed cutting guide offer a significantly shorter surgical time, which is associated with a reduction in hospital days, PACU days, and complications. The cost of CAD/CAM technology is comparable to that of the conventional freehand technique.

Introduction: The management of subcondylar fractures has been very controversial in the maxillofacial literature. The open reduction and internal fixation (ORIF) technique has been considered by many authors the gold standard in selected cases. However, with the rise in endoscopic techniques in the craniomaxillofacial area, new boundaries and less invasive techniques are being explored. The endoscopic approach of subcondylar fractures has proved overall good and similar results to open approaches whilst reducing complications such as facial nerve injury. In this article we purpose to describe our experience with the endoscopic approach to subcondylar fractures. Patients and methods: We retrospectively analyzed 11 patients with subcondylar fractures treated at our department via an endoscopic approach. The number and type of plates used in each patient is recorded. Results and complications observed for all patients are described as well as functional outcomes in terms of mouth opening at 1 week, 3 months and 6 months postoperatively. Results: One patient presented with transient damage to the marginal and frontal branches of the facial nerve. 18.2 % of patients had their hardware removed due to pain or infection at the fracture site. No cases of salivary fistula or sialocele were found in this study. Mean mouth opening at one week postoperatively was 31.8 mm which increased to 37.8 mm at 6 months after surgery, meaning an increase of 18.86 % through the follow-up. Also, 18.2 % of patients presented with persistent deviation with mouth opening and one patient presented with postoperative persistent malocclusion that was treated with intermaxillary fixation and elastics. Conclusion: The endoscopic management of subcondylar fractures is a safe alternative to the open approach, specially in favorable cases, which reduces the risk of complications associa­ted to open approaches, such as unfavorable scarring, salivary gland complications and facial nerve damage. In our series only one patient presented with transient damage to the facial nerve. 18.2 % of the plates were removed, which is a high percentage and should be evaluated, although the small size of the series should be taken into account. Maxillofacial surgeons should be encouraged to learn and trained in endoscopic techniques and include the endoscopic assisted approach in their surgical armamentarium.

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...

The objective of this work was to design and build a fully mechanical knee orthosis. A knee orthosis should both allow control of the angle of flexion of the knee during the stance phase of the gait cycle and leave the joint free during the swing phase. Knee orthoses are normally used to assist the walking of people suffering from muscle weaknesses or gait pathologies in order to avoid excessive knee flexion during the stance phase. The design of the orthosis proposed in the present work is characterized by allowing the knee to be locked at any angle of flexion during the stance phase, and because the orthosis can be unlocked to allow the joint to be released in the swing phase without the action of any external agent, i.e., without requiring external electrical or electronic systems for the control and performance of the orthosis. These characteristics mean that the design can be adapted to the gait of any user. The proposed design consists of a set of three rods, one attached to the user's thigh, another to the calf, and the other to the foot, connected to each other by a self-locking planetary gear train (PGT).

This study will explore the use of a nonlinear relationship between dew point temperature (DPT) and precipitation to apply a method to downscale global circulation models (GCMs) information. Recently, there have been attempts to characterize dew point temperature (DPT) and precipitation intensity. The DPT has shown to be an easier variable to predict, and therefore forecast or prediction on GCM could provide a more reliable estimation. DPT using Clausius-Clapeyron (CC) relationship is one of the methods. This relationship has approximated a non-linear relation into a simple slope coefficient. In a recent study in the Netherlands, DPT was processed by the Advanced Delta Change Method (ADCM) and then converted to precipitation using CC or super CC relation observing better results. In this research work this approach is compared with a non-linear (neural network) model of the relationship. The main contribution of the overall project is to explore the improvement of a better relationship description and how much this could impact in our engineering intensity duration frequency curves. The problem posed is the analysis of the implications of climate change information for civil engineering design in the Metropolitan Area of Monterrey (Santa Catarina River Basin in Mexico).

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.

A procedure for solving, suboptimally, the traveling salesman problem is presented. The set of points on the traveling salesman tour is distributed over a region having the shape of a circular or ring sector. The procedure is based on an optimal partition of the sector and reduces the tour construction to a sorting problem. Namely, the tour is constructed by visiting the points in radial or angular order depending on the part of the sector on which they are located. The optimal partition is derived by a continuous approximation of the set of points. It is defined by a single parameter and simple analytical expressions for it are obtained. A great number of numerical tests were carried out to evaluate the performance of the procedure. These tests allowed a measure of the difference from the optimum solution that could be obtained for problems up to a few hundred points. The results show that the euclidean length of the tours produced by the partition procedure grows, on average, like AN , where A is the region area and N the number of points. The initial tours are improved by means of the Or’s algorithm and the final tours obtained are nearly as good as those given by more intrincate improvement heuristics. The whole procedure, that is, the tour construction and improvement heuristics, is rather simple to implement on a computer, which makes it very appealing to use in routing software.

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.

Percutaneous balloon mitral valvotomy (BMV) is an alternative therapeutic method for patients with mitral stenosis. We studied 62 patients (56 females, mean age 36.4 years) who underwent balloon mitral valvotomy. Five patients were pregnant and in New York Heart Association Functional Class IV. Doppler echocardiographic studies were performed prior to the procedure, and at 7 days, 6 months, 12 months, and 24 months after the procedure. We studied the following parameters: echo-score by the sum of valvular mobility, thickening, and calcification, and subvalvular disease, graded from 1 to 4; and mitral valve area (MVA) and mitral pressure gradient (MPG) by Doppler echocardiography. The patients were separated into two groups: group I with an echo-score less than or equal to 8 (40 patients), and group II with an echo-score greater than or equal to 9 (22 patients). Mitral valve area and MPG were compared with hemodynamics through the correlation coefficient and linear regression. Comparison between groups I and II was performed using the unpaired Student's t-test. Follow-up of MVA and MPG was analyzed by analysis of variance. The Student's t-test did not show any significant difference between MVA and MPG before balloon mitral valvotomy. There was significant decrease of MVA in group II (P less than 0.01) in the last three studies. There was significant increase in MPG in group II (P less than 0.01) in every postvalvotomy study. The analysis of variance of group I showed statistical increase of the MVA, and significant decrease of the MPG after BMV. The analysis of variance of group II showed significant increase in MVA and significant decrease in MPG between the pre- and the first postvalvotomy study. There was significant decrease (P less than 0.01) in MVA, and increase in MPG in the three postvalvotomy studies. Complications included mitral regurgitation, residual interatrial communication, pericardial effusion due to an atrial wall perforation, and peripheral embolization. Atrial fibrillation did not significantly alter the results of BMV. Results were considered positive when MVA was greater than 1.5 cm 2 and area increase was greater than 25%. Patients with an echo-score less than or equal to 8 (group I) benefit from BMV, with a positive predictive value greater than 78%. In pregnant patients the symptomatology was alleviated by BMV, without any signs of fetal compromise.

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 appearance of an intraoral mass is common in our specialty. Most are benign lesions, but some are primary malignancies. Metastases account for less than 1% of all oral malignancies. An 86 year old woman was referred to our department with a large, asymptomatic, intraoral, fast-growing mass. She had no previous cancer history or other relevant physical findings. The radiology studies showed underlying bone erosion. The histological study showed a metastatic adenocarcinoma with a suspected origin in the abdomen. We were unable to identify it by non invasive diagnostic procedures. Given the patient's general status and despite the ominous prognosis of such lesions, we decided not to perform any aggressive therapy beyond removing the oral mass, in order to maintain her quality of life. There have been no local recurrences until this time.

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.

Although lipomas are among the most frequent tumors in the human body, their presentation in the oral cavity is not common. Oral cavity lipomas usually show a slow painless and assymptomatic growing. When these tumors reach big sizes, they can cause compressive symptons and deformities. In this paper we present the case of a patient in whom oral lipoma was the final finding in the differential diagnosis of a chronic mucosal ulcer. CT scan and MRI images and microscopical examination after fine-needle aspiration were the clue for the final diagnosis. The surgical excision of the tumor was the basis for the healing of the ulcer. We also review the most relevant and recent literature about clinic, diagnosis and treatment for these tumors.

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.