378 research outputs found

    Simultaneous laser vibrometry on multiple surfaces with a single beam system using range-resolved interferometry

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    A novel range-resolved interferometric signal processing technique that uses sinusoidal optical frequency modulation is applied to multi-surface vibrometry, demonstrating simultaneous optical measurements of vibrations on two surfaces using a single, collimated laser beam, with a minimum permissible distance of 3.5 cm between surfaces. The current system, using a cost-effective laser diode and a fibre-coupled, downlead insensitive setup, allows an interferometric fringe rate of up to 180 kHz to be resolved with typical displacement noise levels of 8 pm Hz-0.5. In this paper, the system is applied to vibrometry measurements of a table-top cryostat, with concurrent measurements of the optical widow and the sample holder inside. This allows the separation of common-mode vibrations of the whole cryostat from differential vibrations between the window and the sample holder.EPSR

    Trends in the sand: directional evolution in the shell shape of recessing scallops (Bivalvia: Pectinidae)

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    Directional evolution is one of the most compelling evolutionary patterns observed in macroevolution. Yet, despite its importance, detecting such trends in multivariate data remains a challenge. In this study, we evaluate multivariate evolution of shell shape in 93 bivalved scallop species, combining geometric morphometrics and phylogenetic comparative methods. Phylomorphospace visualization described the history of morphological diversification in the group; revealing that taxa with a recessing life habit were the most distinctive in shell shape, and appeared to display a directional trend. To evaluate this hypothesis empirically, we extended existing methods by characterizing the mean directional evolution in phylomorphospace for recessing scallops. We then compared this pattern to what was expected under several alternative evolutionary scenarios using phylogenetic simulations. The observed pattern did not fall within the distribution obtained under multivariate Brownian motion, enabling us to reject this evolutionary scenario. By contrast, the observed pattern was more similar to, and fell within, the distribution obtained from simulations using Brownian motion combined with a directional trend. Thus, the observed data are consistent with a pattern of directional evolution for this lineage of recessing scallops. We discuss this putative directional evolutionary trend in terms of its potential adaptive role in exploiting novel habitats

    Morphological convergence of shell shape in distantly related scallop species (Mollusca: Pectinidae)

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    Morphological convergence is a central concept in evolutionary biology, but convergent patterns remain under-studied in nonvertebrate organisms. Some scallop species exhibit long-distance swimming, a behaviour whose biomechanical requirements probably generate similar selective regimes. We tested the hypothesis that shell shape similarity in long-distance swimming species is a result of convergent evolution. Using landmark-based geometric morphometrics, we quantified shell shape in seven species representing major behavioural habits. All species displayed distinct shell shapes, with the exception of the two long-distance swimmers, whose shells were indistinguishable. These species also displayed reduced morphological variance relative to other taxa. Finally, a phylogenetic simulation revealed that these species were more similar in their shell shape than was expected under Brownian motion, the model of character evolution that best described changes in shell shape. Together, these findings reveal that convergent evolution of shell shape occurs in scallops, and suggest that selection for shell shape and behaviour may be important in the diversification of the group

    Characterisation of a cryostat using simultaneous, single-beam multiple-surface laser vibrometry

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    A novel range-resolved interferometric signal processing technique that uses sinusoidal optical frequency modulation is applied to multi-surface vibrometry, demonstrating simultaneous optical measurements of vibrations on two surfaces using a single, collimated laser beam, with a minimum permissible distance of 3.5 cm between surfaces. The current system, using a cost-effective laser diode and a fibre-coupled, downlead insensitive setup, allows an interferometric fringe rate of up to 180 kHz to be resolved with typical displacement noise levels of 8 pm · Hz−0 5. In this paper, the system is applied to vibrometry measurements of a table-top cryostat, with concurrent measurements of the optical widow and the sample holder target inside. This allows the separation of common-mode vibrations of the whole cryostat from differential vibrations between the window and the target, allowing any resonances to be identified

    Eficiencia técnica del proceso de fotocatálisis heterogénea para la remoción de fármacos en el tratamiento de aguas residuales hospitalarias, 2020

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    La contaminación de las aguas por fármacos es un problema creciente en todo el mundo, aunque los tratamientos comunes de aguas residuales pueden eliminar algunos de estos compuestos, otros pueden persistir en el medio ambiente y ser potencialmente peligrosos para los ecosistemas acuáticos y para la salud pública. El proceso de fotocatálisis heterogénea es una técnica altamente eficiente en la remoción de fármacos y otros contaminantes. El objetivo de la presente investigación es determinar la eficiencia técnica del proceso de fotocatálisis heterogénea para la remoción de fármacos en el tratamiento de aguas residuales hospitalarias. Se realizó una búsqueda exhaustiva en 10 bases de datos y o plataformas como: Redalyc, SciELO, Google Scholar, revistas de índole científico y repositorios institucionales de diferentes universidades y organizaciones, contando con la revisión completa, tras aplicar los criterios de inclusión y exclusión, de 24 publicaciones, en la presente investigación. Se concluyó que la aplicación de la fotocatálisis heterogénea en aguas residuales hospitalarias es altamente efectiva para la remoción de ibuprofeno y diclofenaco, y optimiza los parámetros fisicoquímicos Demanda Bioquímica de Oxígeno y Demanda Química de Oxígeno

    Isokinetic Muscle Strength and Fatigue Evaluation Following a Combined Aerobic and Resistance Training Program on a Gravity Independent Flywheel Device

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    Exposure to microgravity imposes changes on the musculoskeletal and cardiovascular systems leading to decreases in aerobic capacity, muscular strength, and muscular fatigue (1). Anti-gravity muscles, those that play a postural role in a standard gravity environment such as the soleus and quadriceps, are most affected by microgravity (2) with nearly all musculature affected with extended spaceflight (3). The multi-mode exercise device (M-MED) is a gravity independent device that provides both high force resistance type and low force aerobic type modes of exercise. Consequently, the M-MED has the ability to enhance both skeletal muscle function through resistance training exercises as well as cardiovascular function with aerobic training

    A single domain antibody fragment that recognizes the adaptor ASC defines the role of ASC domains in inflammasome assembly

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    Myeloid cells assemble inflammasomes in response to infection or cell damage; cytosolic sensors activate pro–caspase-1, indirectly for the most part, via the adaptors ASC and NLRC4. This leads to secretion of proinflammatory cytokines and pyroptosis. To explore complex formation under physiological conditions, we generated an alpaca single domain antibody, VHH[subscript ASC], which specifically recognizes the CARD of human ASC via its type II interface. VHH[subscript ASC] not only impairs ASC[subscript CARD] interactions in vitro, but also inhibits inflammasome activation in response to NLRP3, AIM2, and NAIP triggers when expressed in living cells, highlighting a role of ASC in all three types of inflammasomes. VHH[subscript ASC] leaves the Pyrin domain of ASC functional and stabilizes a filamentous intermediate of inflammasome activation. Incorporation of VHH[subscript ASC]-EGFP into these structures allowed the visualization of endogenous ASC[superscript PYD] filaments for the first time. These data revealed that cross-linking of ASC[superscript PYD] filaments via ASC[superscript CARD] mediates the assembly of ASC foci.National Institutes of Health (U.S.) (Pioneer Award
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