Testing GeoGebra as an effective tool to improve the understanding of the concept of limit on engineering students

The impact GeoGebra on the teaching of the concept of limit was analyzed. Two groups of engineering students, studying differential calculus, served as control and test groups. The traditional teaching, based on examples solved by hand, was given to the control group while a series of activities involving the usage of the mathematical software GeoGebra were applied in an attempt of improving the degree of assimilation on the concept of limits

Paleoseismological evidence of holocene activity of the Los Tollos fault (Murcia, se Spain): a lately formed quaternary tectonic feature of the eastern betic shear zone

The Los Tollos Fault is a recent and important feature of the Eastern Betic Shear Zone, one of the major tectonic structures in South Iberia accommodating the convergence between Nubian and Eurasian plates in the western Mediterranean. The Los Tollos Fault became active by the end of Middle Pleistocene introducing some paleogeographical modifications. Previously mapped as a secondary normal fault related to the Carrascoy Fault, recent research evidences that the Los Tollos Fault is an independent Holocene active left-lateral reverse fault extending for at least 15 km. Data analysis from 4 trenches dug across the fault has revealed the occurrence of at least two paleo-earthquake events during the Holocene. The most recent event is dated between 2,740 and 2,140 yr BP (8th to 2nd centuries BC). The size of the paleoevents is calculated to be Mw 6.3 – 6.6 following empirical regressions on surface rupture length. The recurrence interval is estimated to be between 2,200-6,860 years, fitting a slip rate for the fault between 0.12 and 0.17 mm/yr. Such parameters highlight the Los Tollos Fault as a tectonic structure with a considerable activity located relatively close to densely populated areas. These seismogenic parameters should be considered in future reassessments of the seismic hazard of the regionThis work forms part of the research activities carried out in the FASEGEO Project (CGL2009-09726) funded by the Spanish Ministry of Science and Innovatio

On Optimal Coverage of a Tree with Multiple Robots

We study the algorithmic problem of optimally covering a tree with $k$ mobile robots. The tree is known to all robots, and our goal is to assign a walk to each robot in such a way that the union of these walks covers the whole tree. We assume that the edges have the same length, and that traveling along an edge takes a unit of time. Two objective functions are considered: the cover time and the cover length. The cover time is the maximum time a robot needs to finish its assigned walk and the cover length is the sum of the lengths of all the walks. We also consider a variant in which the robots must rendezvous periodically at the same vertex in at most a certain number of moves. We show that the problem is different for the two cost functions. For the cover time minimization problem, we prove that the problem is NP-hard when $k$ is part of the input, regardless of whether periodic rendezvous are required or not. For the cover length minimization problem, we show that it can be solved in polynomial time when periodic rendezvous are not required, and it is NP-hard otherwise

Morris water maze overtraining increases the density of thorny excrescences in the basal dendrites of CA3 pyramidal neurons

The hippocampus plays a fundamental role in spatial learning and memory. Dentate gyrus (DG) granular neurons project mainly to proximal apical dendrites of neurons in the CA3 stratum lucidum and also, to some extent, to the basal dendrites of CA3 pyramidal cells in the stratum oriens. The terminal specializations of DG neurons are the mossy fibers (MF), and these huge axon terminals show expansion in the CA3 stratum oriens after the animals undergo overtraining in the Morris Water Maze task (MWM). However, to our knowledge there are no reports regarding the possible changes in density of post-synaptic targets of these terminals in the basal dendrites of CA3 neurons after overtraining in the MWM. The purpose of this work was to study the density of thorny excrescences (TE) and other dendritic spine types (stubby, thin, and mushroom) in the CA3 stratum oriens in animals overtrained in the MWM for three consecutive days and in animals trained for only one day. Seven days after MWM training, the animals were sacrificed, and their brains removed and processed for rapid Golgi staining to visualize the different types of dendritic protrusions. Our results revealed that the relative quantity of stubby, thin, and mushroom dendritic spines did not change, regardless of amount of training. However, a significant increase in the density of TE was detected in the overtrained animals. These results strongly suggest that spatial water maze overtraining induces an increased density of MF–TE connections, which might be functionally relevant for long-term spatial memory formation.Fil: Gómez Padilla, Eurídice. Universidad Autonoma de Queretaro.; MéxicoFil: Bello Medina, Paola C.. Universidad Nacional Autónoma de México; MéxicoFil: León Jacinto, Uriel. Universidad Nacional Autónoma de México; MéxicoFil: Orta Salazar, Erika. Universidad Nacional Autónoma de México; MéxicoFil: Quirarte, Gina L.. Universidad Nacional Autónoma de México; MéxicoFil: Ramirez Amaya, Victor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentina. Universidad Autonoma de Queretaro.; MéxicoFil: Prado Alcalá, Roberto A.. Universidad Nacional Autónoma de México; MéxicoFil: Díaz Cintra, Sofía. Universidad Nacional Autónoma de México; Méxic

Paleoseismological evidence of Holocene activity of the Los Tollos Fault (Murcia, SE Spain): A lately formed Quaternary tectonic feature of the Eastern Betic Shear Zone

The Los Tollos Fault is a recent and important feature of the Eastern Betic Shear Zone, one of the major tectonic structures in South Iberia accommodating the convergence between Nubian and Eurasian plates in the western Mediterranean. The Los Tollos Fault became active by the end of Middle Pleistocene introducing some paleogeographical modifications. Previously mapped as a secondary normal fault related to the Carrascoy Fault, recent research evidences that the Los Tollos Fault is an independent Holocene active left-lateral reverse fault extending for at least 15 km. Data analysis from 4 trenches dug across the fault has revealed the occurrence of at least two paleo-earthquake events during the Holocene. The most recent event is dated between 2,740 and 2,140 yr BP (8th to 2nd centuries BC). The size of the paleoevents is calculated to be Mw 6.3 – 6.6 following empirical regressions on surface rupture length. The recurrence interval is estimated to be between 2,200-6,860 years, fitting a slip rate for the fault between 0.12 and 0.17 mm/yr. Such parameters highlight the Los Tollos Fault as a tectonic structure with a considerable activity located relatively close to densely populated areas. These seismogenic parameters should be considered in future reassessments of the seismic hazard of the region.La falla de Los Tollos es una estructura reciente e importante de la Zona de Cizalla de la Bética Oriental, la principal estructura del sureste de la Península Ibérica que acomoda gran parte de la convergencia entre las placas de Eurasia y Nubia en el Mediterráneo Occidental. La falla de Los Tollos, descrita inicialmente como una falla normal secundaria relacionada con la falla de Carrascoy, comenzó su actividad a finales del Pleistoceno Medio generando algunas modificaciones paleogeográficas significativas. El trabajo que aquí presentamos demuestra su activad durante el Holoceno con una cinemática lateral sinestral con componente inversa a lo largo de una longitud de 15 km, e independiente de la Falla de Carrascoy. Del análisis de los datos obtenidos en 4 trincheras paleosismológicas realizadas a lo largo de la traza de la falla, se han podido interpretar la ocurrencia de al menos 2 paleoterremotos durante el Holoceno, acotándose el evento más reciente entre hace 2.740 y 2.140 años (siglos VIII a II a.C.). La magnitud máxima de estos paleoterremotos, estimada mediante correlaciones empíricas que consideran la longitud de rotura en superficie de la falla, se encuentra entre Mw 6,3 y 6,6, con un periodo de recurrencia comprendido entre 2.200 y 6.860 años. La tasa de deslizamiento neta calculada para la falla se estima entre 0,12 y 0,17 mm/a. Estos parámetros identifican la falla de Los Tollos como una estructura activa situada en las cercanías de áreas densamente pobladas y ponen de manifiesto el interés que tendría considerarla en futuras reevaluaciones de la peligrosidad sísmica en la región

Increasing contrast improves object perception in Parkinson's disease with visual hallucinations

BACKGROUND: Deficits in basic vision are associated with visual hallucinations in Parkinson's disease. Of particular interest is contrast sensitivity loss in this disorder and its effect on object identification. OBJECTIVES: Evaluate whether increased contrast improves object perception in persons with Parkinson's disease and visual hallucinations, without dementia. METHODS: We assessed 26 individuals with mild to moderate idiopathic Parkinson's disease, half of whom reported one or more episodes of hallucinations/unusual perceptual experiences in the past month, with a letter-identification task that determined the contrast level required to achieve 80% accuracy. Contrast sensitivity was further assessed with a chart that presented stimuli at multiple spatial frequencies. The groups were closely matched for demographic and clinical characteristics except for experience of hallucinations. RESULTS: Relative to participants without visual hallucinations, those with hallucinations had poorer spatial frequency contrast sensitivity and required significantly greater contrast to correctly identify the letters on the identification task. Specifically, participants with hallucinations required a mean contrast of 52.8%, whereas participants without hallucinations required 35.0%. When given sufficient contrast, the groups with and without hallucinations were equally accurate in letter identification. CONCLUSIONS: Compared to those without hallucinations, individuals with Parkinson's disease and hallucinations without dementia showed poorer contrast sensitivity. Once contrast was individually enhanced, the groups were equally accurate at object identification. These findings suggest the potential of visual perception tests to predict, and perception-based interventions to reduce, hallucinations in Parkinson's disease.R01 NS050446 - NINDS NIH HHS; R01 NS067128 - NINDS NIH HHSAccepted manuscrip

Evaluación en campo de material absorbente para recogida de hidrocarburos del petróleo en agua.

Las regulaciones ambientales mundiales recientes para el vertimiento de petróleo en suelos y aguas han obligado a la aplicación de soluciones utilizando materiales absorbentes. Por este motivo, existe la tendencia a buscar materiales de fibras naturales, por su alta capacidad de absorción y biodegradabilidad. El presente trabajo tiene como objetivo, evaluar la capacidad de absorción de hidrocarburos en agua superficial de un material absorbente elaborado a partir de   bagazo modificado. Para determinar dicha capacidad se realizaron pruebas en condiciones dinámicas en una fase acuosa en movimiento (condiciones hidrofílicas) conteniendo hidrocarburos (condiciones oleofílicas) y se realizaron dos pruebas de acuerdo al método (F 726-06 ASTM, 2006) para absorbentes tipo II. La prueba de campo se ejecutó en la laguna de residuales de una Empresa Comercializadora de Combustibles depositando almohadillas absorbentes con un peso base seca de 4 kg. Transcurrido el tiempo de la prueba dinámica fueron retiradas y pesadas. La cantidad de hidrocarburo absorbido se determinó por el método gravimétrico. La mejor capacidad de absorción fue de 2,24 g de hidrocarburo/4 kg de absorbente, obtenida a las 24 horas de haber depositado el material, siendo estos resultados similares a los reflejados en la literatura para este tipo de materia

Benchmarking of human Y-chromosomal haplogroup classifiers with whole-genome and whole-exome sequence data

In anthropological, medical, and forensic studies, the nonrecombinant region of the human Y chromosome (NRY) enables accurate reconstruction of pedigree relationships and retrieval of ancestral information. Using high-throughput sequencing (HTS) data, we present a benchmarking analysis of command-line tools for NRY haplogroup classification. The evaluation was performed using paired Illumina data from whole-genome sequencing (WGS) and whole-exome sequencing (WES) experiments from 50 unrelated donors. Additionally, as a validation, we also used paired WGS/WES datasets of 54 individuals from the 1000 Genomes Project. Finally, we evaluated the tools on data from third-generation HTS obtained from a subset of donors and one reference sample. Our results show that WES, despite typically offering less genealogical resolution than WGS, is an effective method for determining the NRY haplogroup. Y-LineageTracker and Yleaf showed the highest accuracy for WGS data, classifying precisely 98% and 96% of the samples, respectively. Yleaf outperforms all benchmarked tools in the WES data, classifying approximately 90% of the samples. Yleaf, Y-LineageTracker, and pathPhynder can correctly classify most samples (88%) sequenced with third-generation HTS. As a result, Yleaf provides the best performance for applications that use WGS and WES. Overall, our study offers researchers with a guide that allows them to select the most appropriate tool to analyze the NRY region using both second- and third-generation HTS data

Los orígenes de un nuevo gen de diseño de alas de mariposa dentro de una familia de reguladores conservados del ciclo celular

A major challenge in evolutionary biology is to understand the origins of novel structures. The wing patterns of butterflies and moths are derived phenotypes unique to the Lepidoptera. Here we identify a gene that we name poikilomousa (poik), which regulates colour pattern switches in the mimetic Heliconius butterflies. Strong associations between phenotypic variation and DNA sequence variation are seen in three different Heliconius species, in addition to associations between gene expression and colour pattern. Colour pattern variants are also associated with differences in splicing of poik transcripts. poik is a member of the conserved fizzy family of cell cycle regulators. It belongs to a faster evolving subfamily, the closest functionally characterised orthologue being the cortex gene in Drosophila, a female germ-line specific protein involved in meiosis. poik appears to have adopted a novel function in the Lepidoptera and become a major target for natural selection acting on colour and pattern variation in this group