Critical Repetition Rates for Perceptual Segregation of Time-Varying Auditory, Visual and Vibrotactile Stimulation

What sound quality has led to exclude infrasound from sound in the conventional hearing range? We examined whether temporal segregation of pressure pulses is a distinctive property and evaluated this perceptual limit via an adaptive psychophysical procedure for pure tones and carriers of different envelopes. Further, to examine across-domain similarity and individual covariation of this limit, here called the critical segregation rate (CSR), it was also measured for various periodic visual and vibrotactile stimuli. Results showed that sequential auditory or vibrotactile stimuli separated by at least ~80‒90 ms (~11‒12-Hz repetition rates), will be perceived as perceptually segregated from one another. While this limit did not statistically differ between these two modalities, it was significantly lower than the ~150 ms necessary to perceptually segregate successive visual stimuli. For the three sensory modalities, stimulus periodicity was the main factor determining the CSR, which apparently reflects neural recovery times of the different sensory systems. Among all experimental conditions, significant within- and across-modality individual CSR correlations were observed, despite the visual CSR (mean: 6.8 Hz) being significantly lower than that of both other modalities. The auditory CSR was found to be significantly lower than the frequency above which sinusoids start to elicit a tonal quality (19 Hz; recently published for the same subjects). Returning to our initial question, the latter suggests that the cessation of tonal quality — not the segregation of pressure fluctuations — is the perceptual quality that has led to exclude infrasound (sound with frequencies < 20 Hz) from the conventional hearing range

El magmatismo alcalino del Triásico Superior en el NO de la Cadena Ibérica (España)

We have carried out a complete study of the Upper-Triassic alkaline magmatism on the northwestern margin of the Iberian Chain. This magmatism is composed of mafic sills, which intrude the Keuper facies in two geographic sectors: the Cameros Massif (NW) and the Moncayo Massif (SE). In both of these sectors, the rocks are characterised by an intense alteration (spilitisation). The field relationships point to an Upper Triassic age for the studied sills, given that: 1) interactions are recognised between the magma and wet, unconsolidated host sediments, suggesting that the magma was emplaced during or shortly after the deposition of the Keuper facies; 2) in the Moncayo sector a conglomerate bed that includes igneous clasts overlaies the sills and passes upwards to the Norian-Rhaetian Imón Fm. According to the petrological and geochemical features of the sills, an internal differentiation can be recognised inwards, with the developments of three zones: chilled margins, central facies and pegmatoid facies. The rocks are porphyritic and are mainly composed of phenocrysts of pseudomorphed olivine and microcrysts of plagioclase, opaque minerals and minor clinopyroxene. Vesicles and xenoliths of the host sedimentary rocks are also recognised, especially at the chilled margins. The mineral assemblage is constant across the sills but the mineral proportions vary among the different zones. The sills are basic to intermediate rocks. They are classified as basalts to dacites with an alkaline geochemical affinity. According to the trace element contents, this magmatism is related to an enriched sub-lithospheric mantle source affected by crustal contamination. Considering the Upper Triassic magmatisms from southwestern Europe, two types can be distinguished. On the one hand, the magmatisms in the Catalonian Coastal Ranges and SE France are paleogeographically located in the inner platform and are related to deep, astenospheric mantle sources with no evidence of crustal contamination. On the other hand, the magmatisms in the NW Iberian Chain –this study-, the External Betics and the Brescian Prealps are situated in a more litoral position and are related to a shallower, lithospheric mantle with evidence of crustal contamination. These differences could be related to the thickness of the continental crust, which might be thinner in the inner areas of the platform.Se ha realizado un estudio completo del magmatismo alcalino del Triásico Superior del margen noroccidental de la Cadena Ibérica. Este magmatismo consta de sills máficos emplazados entre los materiales sedimentarios de la Facies Keuper en dos sectores: Macizo de Cameros (NO) y Macizo del Moncayo (SE). En ambos sectores, las rocas estudiadas se caracterizan por una intensa alteración (espilitización). Las relaciones de campo apuntan a una edad de los sills estudiados de Triásico Superior dado que: 1) se reconocen interacciones entre el magma y el sedimento encajante sin consolidar, que sugieren su emplazamiento coetáneo con el depósito de la facies Keuper o poco posterior y, 2) se observa, en el sector de Moncayo, un nivel conglomerático con cantos de rocas ígneas similares a las que forman los sills, depositado entre los sedimentos argilíticos que se disponen por encima de los sills y siempre, bajo la Fm. Imón de edad Noriense terminal a Retiense inferior. Las características petrológicas y geoquímicas de los sills sugieren una diferenciación hacia el interior de los mismos, reconociéndose tres zonas: borde enfriado, facies central y facies pegmatoide. Las rocas son porfídicas y tienen una asociación mineral común formada por fenocristales de olivino alterado y una mesostasia compuesta por microcristales de plagioclasa, opacos y clinopiroxeno. También se reconocen vesículas y enclaves de la roca sedimentaria encajante, especialmente en el borde enfriado. Las proporciones modales varían entre las tres facies reconocidas. Los sills están formados por rocas básicas a intermedias, clasificadas desde basaltos a dacitas, con afinidad alcalina. De acuerdo a sus contenidos en elementos traza, este magmatismo está relacionado con una fuente mantélica sublitosférica enriquecida, afectada por contaminación cortical. Considerando los magmatismos del Triásico Superior del suroeste de Europa, pueden establecerse dos tipos. Por un lado, los magmatismos aflorantes en las Cadenas Costero Catalanas y el Sur de Francia estaban paleogeográficamente situadas hacia zonas internas de la plataforma y se relacionan con un manto profundo, astenosférico, sin evidencias de contaminación cortical. Por el contrario, los magmatismos de las áreas más occidentales y septentrionales (NO de la Cadena Ibérica –este estudio-, Zonas Externas de las Béticas y Prealpes de Brescia), próximas al litoral paleogeográfico, se relacionan con un manto más superficial, litosférico y muestran evidencias de contaminación cortical. Todas estas diferencias observadas pueden relacionarse con variaciones del espesor de la corteza continental, más adelgazada hacia las zonas internas de la plataforma

Superelastic damping at nanoscale in ternary and quaternary Cu-based shape memory alloys

Superelasticity is a characteristic thermomechanical property in shape memory alloys (SMA), which is due to a reversible stress-induced martensitic transformation. Nano-compression experiments made possible the study of this property in Cu–Al–Ni SMA micropillars, showing an outstanding ultra-high mechanical damping capacity reproducible for thousands of cycles and reliable over the years. This scenario motivated the present work, where a comparative study of the damping capacity on four copper-based SMA: Cu–Al–Ni, Cu–Al–Be, Cu–Al–Ni–Be and Cu–Al–Ni–Ga is approached. For this purpose, [001] oriented single-crystal micropillars of comparable dimensions (around 1 µm in diameter) were milled by focused ion beam technique. All micropillars were cycled up to two hundred superelastic cycles, exhibiting a remarkable reproducibility. The damping capacity was evaluated through the dimensionless loss factor η, calculated for each superelastic cycle, representing the dissipated energy per cycle and unit of volume. The calculated loss factor was averaged between three micro-pillars of each alloy, obtaining the following results: Cu–Al–Ni η = 0.20 ± 0.01; Cu–Al–Be η = 0.100 ± 0.006; Cu–Al–Ni–Be η = 0.072 ± 0.004 and Cu–Al–Ni–Ga η = 0.042 ± 0.002. These four alloys exhibit an intrinsic superelastic damping capacity and offer a wide loss factor band, which constitutes a reference for engineering, since this kind of micro/nano structures can potentially be integrated not only as sensors and actuators but also as dampers in the design of MEMS to improve their reliability. In addition, the study of the dependence of the superelastic loss factor on the diameter of the pillar was approached in the Cu–Al–Ni–Ga alloy, and here we demonstrate that there is a size effect on damping at the nanoscale.Fil: Gómez Cortés, J.F.. Universidad del País Vasco; EspañaFil: Fuster, Valeria de Los Angeles. Universidad del País Vasco; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Física de Rosario. Universidad Nacional de Rosario. Instituto de Física de Rosario; ArgentinaFil: Pérez Cerrato, M.. Universidad del País Vasco; EspañaFil: Lorenzo, P.. Universidad del País Vasco; EspañaFil: Ruiz Larrea, I.. Universidad del País Vasco; EspañaFil: Breczewski, T.. Universidad del País Vasco; EspañaFil: Nó, M. L.. Universidad del País Vasco; EspañaFil: San Juan, J. M.. Universidad del País Vasco; Españ

DNA-barcoding revela la existencia de un posible nuevo género del complejo Laurencia (Rodophyta, Ceramiales) en las islas Canarias

XIX Simposio de Botánica Criptogámica, Las Palmas de Gran Canaria, 24-28 de junio de 2013.Basado en análisis morfológicos y moleculares, en la actualidad el complejo Laurencia (Rhodophyta, Ceramiales) incluye seis géneros (Chondrophycus, Laurencia, Laurenciella, Osmundea, Palisada y Yuzurua). El objetivo principal de este estudio preliminar es valorar a nivel molecular la posible existencia de un nuevo género dentro del complejo Laurencia presente en las Islas Canarias, así como establecer posibles relaciones filogenéticas entre éste y otros taxones del complejo citados en la Macaronesia

A molecular perspective of the Laurencia complex (Ceramiales, Rhodophyta) in Macaronesia region

IV Congress of Marine Sciences. Las Palmas de Gran Canaria, June 11th to 13th 2014.In the present study, we undertook an integrative approach, using molecular data to assess the diversity of the Laurencia complex in Macaronesian islands (Azores, Madeira and Canary Islands) where speciation events are supposedly common leading to a high endemism. Identification of species of the Laurencia complex based on anatomical and morphological characters is extremely difficult due to phenotypic plasticity and overlaps in many morphological characters. As a consequence, among the 28 species reported so far from these Macaronesian archipelagos, 14 species records have been regarded as doubtful. We used DNA barcode data (mitochondrial COI gene and partial nuclear LSU marker) as a tool for species delimitation. A third marker (rbcL gene) was also studied and phylogenetic analyses were carried out using the three independent markers as well as the combined data set, in the aim to infer the phylogenetic relationships and biogeographic affinities of members of the complex from Macaronesia. Our results proved the usefulness of the DNA barcode markers for uncovering several putative new species of the Laurencia complex in Macaronesia and phylogenetic results revealed the existence of a potential new genus present in Canary Islands, which adds to the six pre-existing genera: Laurencia, Osmundea, Chondrophycus, Palisada, Yuzurua and Laurenciella

Topological Defect Densities in Type-I Superconducting Phase Transitions

We examine the consequences of a cubic term addition to the mean-field potential of Ginzburg-Landau theory to describe first order superconductive phase transitions. Constraints on its existence are obtained from experiment, which are used to assess its impact on topological defect creation. We find no fundamental changes in either the Kibble-Zurek or Hindmarsh-Rajantie predictions.Comment: Revtex4, 1 eps figure, 6 pages. Change in title and in sections II and III so to broaden the scope of the paper. Additional author is include

Phase separation and suppression of critical dynamics at quantum transitions of itinerant magnets: MnSi and (Sr1−x_{1-x}Cax_{x})RuO3_{3}

Quantum phase transitions (QPTs) have been studied extensively in correlated electron systems. Characterization of magnetism at QPTs has, however, been limited by the volume-integrated feature of neutron and magnetization measurements and by pressure uncertainties in NMR studies using powderized specimens. Overcoming these limitations, we performed muon spin relaxation ($\mu$SR) measurements which have a unique sensitivity to volume fractions of magnetically ordered and paramagnetic regions, and studied QPTs from itinerant heli/ferro magnet to paramagnet in MnSi (single-crystal; varying pressure) and (Sr$_{1-x}$Ca$_{x}$)RuO$_{3}$ (ceramic specimens; varying $x$). Our results provide the first clear evidence that both cases are associated with spontaneous phase separation and suppression of dynamic critical behavior, revealed a slow but dynamic character of the ``partial order'' diffuse spin correlations in MnSi above the critical pressure, and, combined with other known results in heavy-fermion and cuprate systems, suggest a possibility that a majority of QPTs involve first-order transitions and/or phase separation.Comment: 11 pages, 4 figures, 21 authors, to appear in Nature Physic

Epigenetic Mechanisms Regulate MHC and Antigen Processing Molecules in Human Embryonic and Induced Pluripotent Stem Cells

Background Human embryonic stem cells (hESCs) are an attractive resource for new therapeutic approaches that involve tissue regeneration. hESCs have exhibited low immunogenicity due to low levels of Mayor Histocompatibility Complex (MHC) class-I and absence of MHC class-II expression. Nevertheless, the mechanisms regulating MHC expression in hESCs had not been explored. Methodology/Principal Findings We analyzed the expression levels of classical and non-classical MHC class-I, MHC class-II molecules, antigen-processing machinery (APM) components and NKG2D ligands (NKG2D-L) in hESCs, induced pluripotent stem cells (iPSCs) and NTera2 (NT2) teratocarcinoma cell line. Epigenetic mechanisms involved in the regulation of these genes were investigated by bisulfite sequencing and chromatin immunoprecipitation (ChIP) assays. We showed that low levels of MHC class-I molecules were associated with absent or reduced expression of the transporter associated with antigen processing 1 (TAP-1) and tapasin (TPN) components in hESCs and iPSCs, which are involved in the transport and load of peptides. Furthermore, lack of β2-microglobulin (β2m) light chain in these cells limited the expression of MHC class I trimeric molecule on the cell surface. NKG2D ligands (MICA, MICB) were observed in all pluripotent stem cells lines. Epigenetic analysis showed that H3K9me3 repressed the TPN gene in undifferentiated cells whilst HLA-B and β2m acquired the H3K4me3 modification during the differentiation to embryoid bodies (EBs). Absence of HLA-DR and HLA-G expression was regulated by DNA methylation. Conclusions/Significance Our data provide fundamental evidence for the epigenetic control of MHC in hESCs and iPSCs. Reduced MHC class I and class II expression in hESCs and iPSCs can limit their recognition by the immune response against these cells. The knowledge of these mechanisms will further allow the development of strategies to induce tolerance and improve stem cell allograft acceptance