Tecnológico Nacional de México

We present a new strategy called "curvilinear component analysis" (CCA) for dimensionality reduction and representation of multidimensional data sets. The principle of CCA is a self-organized neural network performing two tasks: vector quantization (VQ) of the submanifold in the data set (input space); and nonlinear projection (P) of these quantizing vectors toward an output space, providing a revealing unfolding of the submanifold. After learning, the network has the ability to continuously map any new point from one space into another: forward mapping of new points in the input space, or backward mapping of an arbitrary position in the output space.

Old-growth tropical forests harbor an immense diversity of tree species but are rapidly being cleared, while secondary forests that regrow on abandoned agricultural lands increase in extent. We assess how tree species richness and composition recover during secondary succession across gradients in environmental conditions and anthropogenic disturbance in an unprecedented multisite analysis for the Neotropics. Secondary forests recover remarkably fast in species richness but slowly in species composition. Secondary forests take a median time of five decades to recover the species richness of old-growth forest (80% recovery after 20 years) based on rarefaction analysis. Full recovery of species composition takes centuries (only 34% recovery after 20 years). A dual strategy that maintains both old-growth forests and species-rich secondary forests is therefore crucial for biodiversity conservation in human-modified tropical landscapes.

Abstract This article examines cultural practices that support informal learning as children observe and pitch in with everyday activities that are integrated into family and community life. We discuss the social and cultural grounding of this learning tradition, drawing on research carried out in different parts of the world during more than 60 years. Children learn by watching, listening, and attending, often with great concentration, by taking purposeful initiative, and by contributing and collaborating. We try to correct the frequent misconception that this way of learning is essentially a nonverbal process by showing that speech is commonly used, but judiciously, in support of efficient communication rather than for “lessons.” This learning tradition is not in opposition to school learning; children with schooling experience learn this way when they belong and experience community. [informal learning, cultural practices, socialization, observation, family and community learning]

Biocontrol agents (BCA) have been an important tool in agriculture to prevent crop losses due to plant pathogens infections and to increase plant food production globally, diminishing the necessity for chemical pesticides and fertilizers and offering a more sustainable and environmentally friendly option. Fungi from the genus Trichoderma are among the most used and studied microorganisms as BCA due to the variety of biocontrol traits, such as parasitism, antibiosis, secondary metabolites (SM) production, and plant defense system induction. Several Trichoderma species are well-known mycoparasites. However, some of those species can antagonize other organisms such as nematodes and plant pests, making this fungus a very versatile BCA. Trichoderma has been used in agriculture as part of innovative bioformulations, either just Trichoderma species or in combination with other plant-beneficial microbes, such as plant growth-promoting bacteria (PGPB). Here, we review the most recent literature regarding the biocontrol studies about six of the most used Trichoderma species, T. atroviride, T. harzianum, T. asperellum, T. virens, T. longibrachiatum, and T. viride, highlighting their biocontrol traits and the use of these fungal genera in Trichoderma-based formulations to control or prevent plant diseases, and their importance as a substitute for chemical pesticides and fertilizers.

The coinciding development of multiobjective evolutionary algorithms (MOEAs) and the emergence of complex problem formulation in the finance and economics areas has led to a mutual interest from both research communities. Since the 1990s, an increasing number of works have thus proposed the application of MOEAs to solve complex financial and economic problems, involving multiple objectives. This paper provides a survey on the state-of-the-art of research, reported in the specialized literature to date, related to this framework. The taxonomy chosen here makes a distinction between the (widely covered) portfolio optimization problem and the other applications in the field. In addition, potential paths for future research within this area are identified.

In the last decade, theoretical and applied studies were done in order to provide a suitable definition of fractional derivative, which meets all the requirement of a derivative in its primary sense. It was concluded by some eminent researchers that the Riemann‐Liouville version was the most suitable. However, many numerical approximation of fractional derivative were done with Caputo version. This paper addresses the numerical approximation of fractional differentiation based on the Riemann‐Liouville definition, from power‐law kernel to generalized Mittag‐Leffler‐law via exponential‐decay‐law.

Abstract The demand for high‐performance displays is continuously increasing because of their wide range of applications in smart devices (smartphones/watches), augmented reality, virtual reality, and naked eye 3D projection. High‐resolution, transparent, and flexible displays are the main types of display to be used in future. In the above scenario, the micro‐LEDs (light‐emitting diodes) display which has outstanding features, such as low power consumption, wider color gamut, longer lifetime, and short response‐time, can replace traditional liquid crystal displays and organic LEDs‐based display technologies. However, to attain a remarkable position in future display technology, the micro‐LEDs need to overcome problems associated with mass transfer and its high cost of manufacturing. Besides micro‐LEDs, the other option for future displays includes the usage of color conversion medium (phosphor/ quantum dots) to convert some of the blue light into other colors. In this review, the various mass transfer display technologies and color conversion strategies which are being used for the realization of a full‐color display are discussed.

An approximate method to estimate the maximum lateral deformation demands in multistory buildings responding primarily in the fundamental mode when subjected to earthquake ground motions is presented. This method permits a rapid estimation of the maximum roof displacement and of the maximum interstory drift for a given acceleration time history or for a given displacement response spectrum. A multistory building is modeled as an equivalent continuum structure consisting of a combination of a flexural cantilever beam and a shear cantilever beam. The simplified model is used to investigate the ratio of the spectral displacement to the roof displacement and the ratio of the maximum interstory drift ratio to the roof drift ratio. The effect of the distribution of lateral forces along the height of the building and of the ratio of overall flexural and shear deformations is examined. Lateral deformation demands of a 10-story steel building computed with the simplified method when subjected to various earthquake ground motions are compared with those computed using step-by-step time history analyses. It is shown that the method provides good approximations, which are useful for the preliminary design of new buildings or for a rapid evaluation of existing buildings.

Obesity is a serious medical condition worldwide, which needs new approaches and recognized international consensus in treating diseases leading to morbidity. The aim of this review was to examine heterogeneous links among the various phenotypes of obesity in adults. Proteins and associated genes in each group were analysed to differentiate between biomarkers. A variety of terms for classification and characterization within this pathology are currently in use; however, there is no clear consensus in terminology. The most significant groups reviewed include metabolically healthy obese, metabolically abnormal obese, metabolically abnormal, normal weight and sarcopenic obese. These phenotypes do not define particular genotypes or epigenetic gene regulation, or proteins related to inflammation. There are many other genes linked to obesity, though the value of screening all of those for diagnosis has low predictive results, as there are no significant biomarkers. It is important to establish a consensus in the terminology used and the characteristics attributed to obesity subtypes. The identification of specific molecular biomarkers is also required for better diagnosis in subtypes of obesity.

In this paper, a novel failure-detection technique and its analog circuit for insulated gate bipolar transistors (IGBTs), under open- and short-circuit failures, are proposed. This technique is applied to a three-phase induction-motor (IM) drive system. The detection technique is adapted to detect failures of short-circuit and open-circuit in the IGBT, which is based on gate-signal monitoring. The most important issue of this technique is the reduction of time for fault detection. This is very important in a failure-tolerant IM drive based on the material-redundancy approach or protection systems since the detection must be done before the device is damaged, in approximately less than 10 μs. The experimental test and simulations are presented in order to validate the proposed fault-detection technique, and it is validated, achieving replacement of the damaged element in the most suitable time.

Learning systems have made a significant impact on all areas of engineering problems. They are attractive methods for solving many problems which are too complex, highly non-linear, uncertain, incomplete or non-stationary, and have subtle and interactive exchanges with the environment where they operate. The main aim of the book is to give a systematic treatment of learning automata and to produce a guide to a wide variety of ideas and methods that can be used in learning systems, including enough theoretical material to enable the user of the relevant techniques and concepts to understand why

Chitosan is a naturally occurring compound that can be obtained from deacetylated chitin, which is obtained from various sources such as fungi, crustaceans, and insects. Commercially, chitosan is produced from crustaceans. Based on the range of its molecular weight, chitosan can be classified into three different types, namely, high molecular weight chitosan (HMWC, >700 kDa), medium molecular weight chitosan (MMWC, 150-700 kDa), and low molecular weight chitosan (LMWC, less than 150 kDa). Chitosan shows several properties that can be applied in horticultural crops, such as plant root growth enhancer, antimicrobial, antifungal, and antiviral activities. Nevertheless, these properties depend on its molecular weight (MW) and acetylation degree (DD). Therefore, this article seeks to extensively review the properties of chitosan applied in the agricultural sector, classifying them in relation to chitosan's MW, and its use as a material for sustainable agriculture.

Iron-doped titania photocatalysts with different iron contents were prepared by using a sol−gel method in acidic media. The crystalline structures of the various phases calcined at temperatures ranging from 70 to 800 °C were studied by using the Rietveld technique in combination with XRD experiments. The average crystallite size of the phases, lattice cell parameters, phase concentrations, and titanium cationic defects in the crystalline structures of different samples were quantitatively determined. Both iron content and calcination temperature strongly affected phase transformation and solid-state reaction mechanism. Below 400 °C of calcination, all the samples had some brookite and a majority of anatase phase. Iron ions were uniformly distributed in the interstices of titania crystals to form a titanium−iron solid solution when the samples were calcined at 80, 200, and 400 °C. However, when the temperature was 800 °C, Fe 2 TiO 5 was produced in the sample containing 5 wt % Fe by a reaction between interstitial iron ions and lattice titanium ions, and in the 10 wt % Fe sample through a reaction of hematite with titania phases. The crystalline structures of titania phases were distorted at higher calcination temperature. For the first time, it is possible to show that titanium lattice defects related to the hydroxyl ions in the crystalline structures were created in anatase and rutile phases. The concentration of titanium defects remained almost constant below 400 °C but decreased as the calcination temperature was higher than 600 °C due to the decrease of the hydroxyls in the crystalline structure.

In this paper, we investigated the behavior of 22 co-occurrence statistics combined to six gray-scale quantization levels to classify breast lesions on ultrasound (BUS) images. The database of 436 BUS images used in this investigation was formed by 217 carcinoma and 219 benign lesions images. The region delimited by a minimum bounding rectangle around the lesion was employed to calculate the gray-level co-occurrence matrix (GLCM). Next, 22 co-occurrence statistics were computed regarding six quantization levels (8, 16, 32, 64, 128, and 256), four orientations (0° , 45° , 90° , and 135°), and ten distances (1, 2,...,10 pixels). Also, to reduce feature space dimensionality, texture descriptors of the same distance were averaged over all orientations, which is a common practice in the literature. Thereafter, the feature space was ranked using mutual information technique with minimal-redundancy-maximal-relevance (mRMR) criterion. Fisher linear discriminant analysis (FLDA) was applied to assess the discrimination power of texture features, by adding the first m-ranked features to the classification procedure iteratively until all of them were considered. The area under ROC curve (AUC) was used as figure of merit to measure the performance of the classifier. It was observed that averaging texture descriptors of a same distance impacts negatively the classification performance, since the best AUC of 0.81 was achieved with 32 gray levels and 109 features. On the other hand, regarding the single texture features (i.e., without averaging procedure), the quantization level does not impact the discrimination power, since AUC = 0.87 was obtained for the six quantization levels. Moreover, the number of features was reduced (between 17 and 24 features). The texture descriptors that contributed notably to distinguish breast lesions were contrast and correlation computed from GLCMs with orientation of 90° and distance more than five pixels.

This work evaluates the effects of different concentrations of Hibiscus sabdariffa flower (Jamaica) extracts on the green synthesis of zinc oxide (ZnO), for the photocatalytic degradation of methylene blue (MB). Zinc nitrate is used for the synthesis of ZnO as a source of the zinc ions. Extracts of 1%, 4% and 8% (% weight-volume) of Hibiscus sabdariffa, in an aqueous medium, were used as reducing and stabilizing agents. In FTIR characterization, the ZnO bond was observed at 618 cm−1. By means of XRD, the material was observed to have a hexagonal crystalline phase (Wurzite). Through XPS, the energy values of 1022 eV for Zn and 531 eV for O were observed, showing the chemical state of Zn+2. The morphology of the ZnO nanoparticles (NPs) varies in its semicircular shape and size distributions depending on the extract used, which range from 30 to 8 nm. The values of the band gap decreased from 2.96 to 2.77 eV as the concentration of extract increased. These materials presented good photocatalytic activity, degrading 97% of MB in 150 min, which are efficient results comparable to ZnO NPs green synthesized via other extracts and other methods.

Phytohormones are regulators of plant growth and development, which under different types of stress can play a fundamental role in a plant's adaptation and survival. Some of these phytohormones such as cytokinin, gibberellin, salicylic acid, auxin, and ethylene are also produced by plant growth-promoting bacteria (PGPB). In addition, numerous volatile organic compounds are released by PGPB and, like bacterial phytohormones, modulate plant physiology and genetics. In the present work we review the basic functions of these bacterial phytohormones during their interaction with different plant species. Moreover, we discuss the most recent advances of the beneficial effects on plant growth of the phytohormones produced by PGPB. Finally, we review some aspects of the cross-link between phytohormone production and other plant growth promotion (PGP) mechanisms. This work highlights the most recent advances in the essential functions performed by bacterial phytohormones and their potential application in agricultural production.

Cardiovascular diseases (CVDs) are the leading cause of death globally. An effective strategy to mitigate the burden of CVDs has been to monitor patients' biomedical variables during daily activities with wearable technology. Nowadays, technological advance has contributed to wearables technology by reducing the size of the devices, improving the accuracy of sensing biomedical variables to be devices with relatively low energy consumption that can manage security and privacy of the patient's medical information, have adaptability to any data storage system, and have reasonable costs with regard to the traditional scheme where the patient must go to a hospital for an electrocardiogram, thus contributing a serious option in diagnosis and treatment of CVDs. In this work, we review commercial and noncommercial wearable devices used to monitor CVD biomedical variables. Our main findings revealed that commercial wearables usually include smart wristbands, patches, and smartwatches, and they generally monitor variables such as heart rate, blood oxygen saturation, and electrocardiogram data. Noncommercial wearables focus on monitoring electrocardiogram and photoplethysmography data, and they mostly include accelerometers and smartwatches for detecting atrial fibrillation and heart failure. However, using wearable devices without healthy personal habits will cause disappointing results in the patient's health.

BACKGROUND: The double-blind, placebo-controlled Sildenafil in Treatment-Naive Children, Aged 1 to 17 Years, With Pulmonary Arterial Hypertension (STARTS-1) study assessed sildenafil in pediatric patients with pulmonary arterial hypertension; improved hemodynamics and exercise capacity occurred in medium- and high-dose groups. STARTS-2 was the extension study. METHODS AND RESULTS: In STARTS-1, 234 children ≥8 kg were randomly assigned to low-, medium-, or high-dose sildenafil or placebo orally thrice daily; within-group dose depended on weight. In STARTS-2, sildenafil-treated patients continued STARTS-1 dosing; placebo-treated patients were randomized to 1 of the 3 sildenafil dose groups. Patients requiring additional pulmonary arterial hypertension-specific therapy discontinued study treatment; survival follow-up was attempted. As of August 2011, all children received ≥3 years of treatment (unless discontinued) from STARTS-1 baseline; 37 deaths were reported (26 on study treatment), 1 of which occurred within the first year of treatment. Most patients who died (28/37) had idiopathic/heritable pulmonary arterial hypertension (76% versus 33% overall) and baseline functional class III/IV disease (38% versus 15% overall); patients who died had worse baseline hemodynamics. Kaplan-Meier estimated 3-year survival rates from start of sildenafil were 94%, 93%, and 88% for patients randomized to low-, medium-, and high-dose sildenafil, respectively; 87%, 89%, and 80% were known to be alive at 3 years. Hazard ratios for mortality were 3.95 (95% confidence interval, 1.46-10.65) for high versus low and 1.92 (95% confidence interval, 0.65-5.65) for medium versus low dose; however, multiple analyses raised uncertainty about the survival/dose relationship. CONCLUSIONS: Although children randomized to higher compared with lower sildenafil doses had an unexplained increased mortality, all sildenafil dose groups displayed favorable survival for children with pulmonary arterial hypertension. CLINICAL TRIAL REGISTRATION URL: http://clinicaltrials.gov/ct2/show/NCT00159874 (extension study of NCT00149913). Unique identifier: NCT00159874.

BACKGROUND: Biofilms contribute to the pathogenesis of many forms of Staphylococcus aureus infection. Treatment of these infections is complicated by intrinsic resistance to conventional antibiotics, thus creating an urgent need for strategies that can be used for the prevention and treatment of biofilm-associated infections. METHODOLOGY/PRINCIPAL FINDINGS: This study demonstrates that a botanical natural product composition (220D-F2) rich in ellagic acid and its derivatives can limit S. aureus biofilm formation to a degree that can be correlated with increased antibiotic susceptibility. The source of this composition is Rubus ulmifolius Schott. (Rosaceae), a plant used in complementary and alternative medicine in southern Italy for the treatment of skin and soft tissue infections. All S. aureus clonal lineages tested exhibited a reduced capacity to form a biofilm at 220D-F2 concentrations ranging from 50-200 µg/mL, which were well below the concentrations required to limit bacterial growth (530-1040 µg/mL). This limitation was therapeutically relevant in that inclusion of 220D-F2 resulted in enhanced susceptibility to the functionally-distinct antibiotics daptomycin, clindamycin and oxacillin. Testing with kidney and liver cell lines also demonstrated a lack of host cell cytotoxicity at concentrations of 220D-F2 required to achieve these effects. CONCLUSIONS/SIGNIFICANCE: These results demonstrate that extract 220D-F2 from the root of Rubus ulmifolius can be used to inhibit S. aureus biofilm formation to a degree that can be correlated with increased antibiotic susceptibility without toxic effects on normal mammalian cells. Hence, 220D-F2 is a strong candidate for development as a botanical drug for use in the prevention and treatment of S. aureus biofilm-associated infections.

Despite occupying an area no greater than 8% of the earth’s surface, natural wetland ecosystems fulfill multiple ecological functions: 1. Soil formation and stabilization support, 2. Food, water, and plant biomass supply, 3. Cultural/recreational services, landscape, and ecological tourism, 4. Climate regulation, and 5. Carbon sequestration; with the last one being its most important function. They are subject to direct and indirect incident factors that affect plant productivity and the sequestration of carbon from the soil. Thus, the objective of this review was to identify the incident factors in the loss of area and carbon sequestration in marine, coastal, and continental wetlands that have had an impact on climate change in the last 14 years, globally. The methodology consisted of conducting a literature review in international databases, analyzing a sample of 134 research studies from 37 countries, organized in tables and figures supported by descriptive statistics and content analysis. Global results indicate that agriculture (25%), urbanization (16.8%), aquaculture (10.7%), and industry (7.6%) are incident factors that promote wetlands effective loss affecting continental wetlands more than coastal and marine ones. Regarding carbon sequestration, this is reduced by vegetation loss since GHG emissions raise because the soil is exposed to sun rays, increasing surface temperature and oxidation, and raising organic matter decomposition and the eutrophication phenomenon caused by the previous incident factors that generate wastewater rich in nutrients in their different activities, thus creating biomass and plant growth imbalances, either at the foliage or root levels and altering the accumulation of organic matter and carbon. It is possible to affirm in conclusion that the most affected types of wetlands are: mangroves (25.7%), lagoons (19.11%), and marine waters (11.7%). Furthermore, it was identified that agriculture has a greater incidence in the loss of wetlands, followed by urbanization and industry in a lower percentage.