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A chain formation strategy based on mobile frames for a set of n differential drive mobile robots is presented. Considering two consecutive robots in the formation, robots Ri and Ri+1. It is intended that robot Ri+1 follows the delayed trajectory, τ units of time, of the leader robot Ri. In this way, the follower robot Ri+1 becomes the leader robot for robot Ri+ 2 in the formation and so on. With this formation policy, the trailing distance between two consecutive robots varies accordingly to the velocity of the Ri leader robot. Mobile frames are located on the body of the vehicles, in such a way that the position of robot Ri is determined with respect to the frame located on Ri+1 robot. The strategy relies on the fact that the general leader robot R1 describes any trajectory generated by bounded linear v1(t) and angular ω1(t) velocities. For the remaining vehicles in the string, the strategy considers a desired trajectory for the follower robot Ri+1 obtained by an estimation of the delayed trajectory of the leader robot Ri. This desired estimated trajectory is obtained under the knowledge of the actual and past input velocities of the Ri robot. To formally prove the convergence of the formation strategy, the equations describing the time variation of the relative posture between any pair of consecutive vehicles in the formation are obtained, and a feedback law based on local measurements is proposed to get the convergence of robot Ri+1 to the delayed trajectory, τ units of time, of the trajectory previously described by robot Ri. Lyapunov techniques are considered for this fact. The effectiveness of the chain formation solution is evaluated by means of numerical simulations and real time experiments showing an adequate convergence.

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ABSTRACT The aim of this paper is to show a technique to speed up the interpretation of bone scans in order to determine the presence of early bone metastasis. This is done using the gray levels histogram of the region of interest. The technique is intended to assist in the bone scans interpretation in order to provide a successful diagnosis. During the analysis, three types of histograms were observed on the regions of interest. If the histogram is narrow and shifted toward the origin, the bone scan is free of metastasis. If it is shifted to the right and slightly broadened, indicates the presence of a bone anomaly different from a metastasis. On the other hand, if the histogram is more broadened and shifted to the right, is suggests the presence of metastasis. This histogram is characterized by displaying small curls on the right side providing information about the metastatic disease stage, which could be low-amplitude peaks and have a short length, if the metastasis is in early stage, or high-amplitude peaks and a long length, if is advanced. Finally, the analyzed region is displayed in false color considering the minimum gray levels observed in the histogram.

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Culex (Microculex) daumastocampa Dyar & Knab was originally described by Dyar and Knab (Proc US Nat Mus 35:53-70, 1908) from larvae collected at axils of bromeliads in Port San Felipe, Panama. Culex daumastocampa is found in Colombia, Venezuela, Panama, Suriname, Costa Rica, Nicaragua, Guatemala, and Mexico, although its presence had not been reported suggesting its northernmost distribution. In Mexico, the subgenus Microculex had included Cx. rejector Dyar and Knab, and Cx. imitator Theobald. However, after that collection specimens were re-examined along with other specimens collected during 2016 in Chiapas (all specimens are available in the Culicidae Collection of the Universidad Autonoma Agraria Antonio Narro Unidad Laguna [UAAAN-UL], Mexico). Culex daumastocampa is now reported for the first time in Mexico, Cx. rejector for Chiapas, and Cx. imitator removed from the checklist of previous reports as to be present in Mexico.

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This article presents the design of a sensor Fault Detection and Isolation (FDI) system for a condensation process based on a nonlinear model. The condenser is modeled by dynamic and thermodynamic equations. For this work, the dynamic equations are described by three pairs of differential equations which represent the energy balance between the fluids. The thermodynamic equations consist in algebraic heat transfer equations and empirical equations, that allow for the estimation of heat transfer coefficients. The FDI system consists of a bank of two nonlinear high-gain observers, in order to detect, estimate and to isolate the fault in any of both outlet temperature sensors. The main contributions of this work were the experimental validation of the condenser nonlinear model and the FDI system.

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BACKGROUND AND OBJECTIVE: Multidisciplinary management of Duchenne Muscular Dystrophy (DMD) has achieved outstanding results in developed nations. We aimed to describe the status of diagnosis and management of DMD in a developing country through the experience of non-profit organizations. METHODS: A Multistate, multiple-source, population-based survey was performed from medical records of 432 patients. Data were retrospectively collected, reviewed and curated by health specialists; including clinical features, age at first symptoms, age at diagnosis, disease progression and management, family history, education, age and cause of death. RESULTS: There is a delay in noticing first symptoms and it did not diminish over the past 20 years. Less than 30% of patients obtained definite diagnosis and most of them are in physiotherapy programs but not under steroid treatment. In our study, family history does not anticipate recognition of symptoms compared to sporadic cases (p = 0.05). Approximately 93.33% of our patients attended to education programs. Mean age at death was 18.94 +/- 6.73 years and the most frequent cause was pneumonia. CONCLUSION: Delayed diagnosis of DMD in Mexico is mainly caused by the late detection of first symptoms. There is no difference in early detection of symptoms between familiar and sporadic cases. Lifespan of patients in our cohort is reduced compared to developed countries. The late diagnosis and low percentage of definite cases may affect patient management and genetic counseling and could also preclude participation of patients into novel clinical trials.

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Gilbert syndrome (GS) is a hereditary relatively common benign unconjugated hyperbilirubinaemia. The promoter region of uridine diphosphate glycosyltransferase 1 (UGT1A1) gene contains a normal A (TA)6TAA element; variations in this motif (A(TA)7/8TAA) are generally associated with this disorder This is a report of the varied effects of GS in a Mexican Mestizo family with a non-common (TA)8 repeat in this population. The proposita and her mother showed (TA)7/(TA)8 genotype, while her father and sister were (TA)6/(TA)7, but only the proposita showed clinical manifestations. This report supports that the (TA)7 and (TA)8 are necessary, but not enough to explain the features of GS. There are probably additional genetic variations ie, the presence of "modifier" genes or one can speculate that an oligogenetic trait can contribute to the expression of the final phenotype.

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UNLABELLED: In patients undergoing long bone resection for osteosarcoma the use of bone allografts is a treatment option. How do they behave functionally and what is their long term osteointegration? MATERIAL AND METHODS: A retrospective, observational, longitudinal study was conducted to obtain clinical and radiologic data of the sample composed of a group of 15 patients with a diagnosis of limb osteosarcoma treated at our hospital with structural bone allografts. The Mankin and ISOLS (International Symposium on Limb Salvage) scales were applied to assess allograft functionality and osteointegration, respectively, from 1993 to 2006. RESULTS: Functional results were as follows: excellent, 10 patients (66.6%); good, one patient (6.6%), and poor, 4 patients (26%). The osteointegration assessment reported excellent results in 77% of cases at 18 months and in 87% at 2 years. Surgical wound infection was reported as a complication in only 2 patients (13.3%). CONCLUSIONS: Functionality and osteointegration in patients undergoing conservative surgery with bone allografts are excellent in most cases, and this is the technique of choice for the treatment of long bone osteosarcomas.

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This paper deals with fault detection and isolation (FDI) in sensors applied to a concentric-pipe counter-flow heat exchanger. The proposed FDI is based on the analytical redundancy implementing nonlinear high-gain observers which are used to generate residuals when a sensor fault is presented (as software sensors). By evaluating the generated residual, it is possible to switch between the sensor and the observer when a failure is detected. Experiments in a heat exchanger pilot validate the effectiveness of the approach. The FDI technique is easy to implement allowing the industries to have an excellent alternative tool to keep their heat transfer process under supervision. The main contribution of this work is based on a dynamic model with heat transfer coefficients which depend on temperature and flow used to estimate the output temperatures of a heat exchanger. This model provides a satisfactory approximation of the states of the heat exchanger in order to allow its implementation in a FDI system used to perform supervision tasks.

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A possible consequence of planting genetically modified organisms (GMOs) in centres of crop origin is unintended gene flow into traditional landraces. In 2001, a study reported the presence of the transgenic 35S promoter in maize landraces sampled in 2000 from the Sierra Juarez of Oaxaca, Mexico. Analysis of a large sample taken from the same region in 2003 and 2004 could not confirm the existence of transgenes, thereby casting doubt on the earlier results. These two studies were based on different sampling and analytical procedures and are thus hard to compare. Here, we present new molecular data for this region that confirm the presence of transgenes in three of 23 localities sampled in 2001. Transgene sequences were not detected in samples taken in 2002 from nine localities, while directed samples taken in 2004 from two of the positive 2001 localities were again found to contain transgenic sequences. These findings suggest the persistence or re-introduction of transgenes up until 2004 in this area. We address variability in recombinant sequence detection by analyzing the consistency of current molecular assays. We also present theoretical results on the limitations of estimating the probability of transgene detection in samples taken from landraces. The inclusion of a limited number of female gametes and, more importantly, aggregated transgene distributions may significantly lower detection probabilities. Our analytical and sampling considerations help explain discrepancies among different detection efforts, including the one presented here, and provide considerations for the establishment of monitoring protocols to detect the presence of transgenes among structured populations of landraces.

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Oxidative stress is related to an imbalance between the production of reactive species and the antioxidant defenses. In essence, oxidative stress has been defined as a disturbance in the pro-oxidant/antioxidant balance, leading to potential damage. It has been suggested that oxidative stress is involved in the etiology of several chronic diseases including cardiovascular disease, diabetes, cancer and neurodegenerative processes. The antioxidant defenses include nonenzymatic (especially dietary antioxidants) and antioxidant enzymes. Vitamins, minerals and phytochemicals (polyphenols and carotenoids) are among the major dietary antioxidants. The assessment of oxidative stress status though specific biomarkers has acquired great importance. The major biomarkers include the products of the attack of free radicals and reactive species to various substrates: lipids, proteins and nucleic acids. Measurement of antioxidant capacity may also involve the assessment of specific oxidative stress biomarkers. Most of the studies that have examined the association between diet and oxidative stress consider the effects of antioxidant supplements (vitamins and minerals), drinks and foods with bioactive compounds or dietary patterns on oxidative stress biomarkers. Some of these studies have demonstrated beneficial results on oxidative stress markers. However, the role of diet on oxidative stress biomarkers remains unclear and represents a potentially fruitful area for further research in the health area.

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