1,809 research outputs found
AnĂĄlisis del fenĂłmeno de la expansividad de materiales en tĂşneles construidos en anhidrita. Consecuencias y experiencias
Los graves problemas geotĂŠcnicos sucedidos en numerosos tĂşneles europeos excavados en materiales que generan problemas de estabilidad, como consecuencia de su expansividad, los convierten en canalizadores de aguas. Estos materiales son fĂĄcilmente lavables al disolverse los sulfatos con el agua, provocando una decompresiĂłn y remoldeo del macizo, agravando y trasladando el problema mĂĄs allĂĄ del inmediato entorno del tĂşnel. En el caso particular de presencia de capas de anhidrita entre argilitas, ademĂĄs de la adopciĂłn de medidas de sostenimiento y revestimiento especiales, el sostenimiento primario y el revestimiento posterior deben ser excepcionalmente resistentes a las presiones que pueden llegar a transmitir el terreno a medio y largo plazo. En este artĂculo se describen los aspectos mĂĄs relevantes de comportamiento hidromecĂĄnico de los suelos y las rocas sulfatadas y se presentan algunas experiencias, concluyendo sobre aspectos asociados al fenĂłmeno de hinchamiento en tĂşneles y su posible tratamiento
Direct glia-to-neuron transdifferentiation gives rise to a pair of male-specific neurons that ensure nimble male mating
Sexually dimorphic behaviours require underlying differences in the nervous system between males and females. The extent to which nervous systems are sexually dimorphic and the cellular and molecular mechanisms that regulate these differences are only beginning to be understood. We reveal here a novel mechanism by which male-specific neurons are generated in Caenorhabditis elegans through the direct transdifferentiation of sex-shared glial cells. This glia-to-neuron cell fate switch occurs during male sexual maturation under the cell-autonomous control of the sex-determination pathway. We show that the neurons generated are cholinergic, peptidergic, and ciliated putative proprioceptors which integrate into male-specific circuits for copulation. These neurons ensure coordinated backward movement along the mateâs body during mating. One step of the mating sequence regulated by these neurons is an alternative readjustment movement performed when intromission becomes difficult to achieve. Our findings reveal programmed transdifferentiation as a developmental mechanism underlying flexibility in innate behaviour
Aportaciones hidrogeolĂłgicas al estudio arqueolĂłgico de los orĂgenes de la Edad del Bronce de La Mancha: la cueva monumentalizada de Castillejo del Bonete (Terrinches, Ciudad Real-EspaĂąa)
Estudios recientes indican que las motillas, asentamientos de la Edad del Bronce de La Mancha, pudieron ser las mĂĄs antiguas captaciones de agua subterrĂĄnea en la PenĂnsula IbĂŠrica. Pero Âżpor quĂŠ no existen motivas en el Campo de Montiel, territorio ubicado tradicionalmente en esta ĂĄrea cultural? En Castillejo del Bonete, sitio arqueolĂłgico situado en esa comarca, existe una cueva que fue utilizada y sellada durante la Prehistoria Reciente. Se presenta ahora la primera investigaciĂłn paleohidrogeolĂłgica interdisciplinar en La Mancha, que ha analizado manantiales y niveles de agua subterrĂĄnea del acuĂfero de Campo de Montiel, asĂ como el interior de la sima de Castillejo del Bonete. Las conclusiones avanzan una relaciĂłn entre el sustrato hidrogeomorfolĂłgico y la distribuciĂłn espacial de las motillas. AdemĂĄs permiten descartar que la sima de Castillejo del Bonete fuera utilizada como mina o como acceso al acuĂfero, dos de las hipĂłtesis de trabajo planteadas. De ese modo cobra fuerza que Castillejo del Bonete fuera un excepcional monumento funerario y simbĂłlico durante el CalcolĂtico y la Edad del Bronce, perteneciente a una nueva clase de asentamientos desconocidos hasta ahora en el grupo cultural de la Edad del Bronce de La Mancha
Mobile Augmented Reality and Language-Related Episodes
Applications of locative media (e.g., placeâbased mobile augmented reality [AR]) are used in various educational content areas and have been shown to provide learners with valuable opportunities for investigationâbased learning, locationâsituated social and collaborative interaction, and embodied experience of place (Squire, 2009; Thorne & Hellermann, 2017; Zheng et al., 2018). Mobile locative media applicationsâ value for language learning, however, remains underinvestigated. To address this lacuna, this study employed the widely used construct of languageârelated episodes (LREs; Swain & Lapkin, 1998) as a unit of analysis to investigate language learning through participation in a mobile AR game. Analysis of videorecorded interactions of four mixedâproficiency groups of game players (two English language learners [ELLs] and one expert speaker of English [ESE] per group) indicates that LREs in this environment were focused on lexical items relevant to the AR tasks and physical locations. Informed by sociocultural theory and conversation analysis, the microgenesis of learnersâ understanding and subsequent use of certain lexical items are indicated in the findings. This understanding of new lexical items was frequently facilitated by ESEsâ assistance and the surrounding physical environment. A strong goal orientation by both ESEs and ELLs was visible, providing implications for taskâbased language teaching approaches
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV
A search for new physics is presented based on an event signature of at least
three jets accompanied by large missing transverse momentum, using a data
sample corresponding to an integrated luminosity of 36 inverse picobarns
collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector
at the LHC. No excess of events is observed above the expected standard model
backgrounds, which are all estimated from the data. Exclusion limits are
presented for the constrained minimal supersymmetric extension of the standard
model. Cross section limits are also presented using simplified models with new
particles decaying to an undetected particle and one or two jets
Combined search for the quarks of a sequential fourth generation
Results are presented from a search for a fourth generation of quarks
produced singly or in pairs in a data set corresponding to an integrated
luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in
2011. A novel strategy has been developed for a combined search for quarks of
the up and down type in decay channels with at least one isolated muon or
electron. Limits on the mass of the fourth-generation quarks and the relevant
Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a
simple extension of the standard model with a sequential fourth generation of
fermions. The existence of mass-degenerate fourth-generation quarks with masses
below 685 GeV is excluded at 95% confidence level for minimal off-diagonal
mixing between the third- and the fourth-generation quarks. With a mass
difference of 25 GeV between the quark masses, the obtained limit on the masses
of the fourth-generation quarks shifts by about +/- 20 GeV. These results
significantly reduce the allowed parameter space for a fourth generation of
fermions.Comment: Replaced with published version. Added journal reference and DO
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