376 research outputs found
Seismometer Detection of Dust Devil Vortices by Ground Tilt
We report seismic signals on a desert playa caused by convective vortices and
dust devils. The long-period (10-100s) signatures, with tilts of ~10
radians, are correlated with the presence of vortices, detected with nearby
sensors as sharp temporary pressure drops (0.2-1 mbar) and solar obscuration by
dust. We show that the shape and amplitude of the signals, manifesting
primarily as horizontal accelerations, can be modeled approximately with a
simple quasi-static point-load model of the negative pressure field associated
with the vortices acting on the ground as an elastic half space. We suggest the
load imposed by a dust devil of diameter D and core pressure {\Delta}Po is
~({\pi}/2){\Delta}PoD, or for a typical terrestrial devil of 5 m diameter
and 2 mbar, about the weight of a small car. The tilt depends on the inverse
square of distance, and on the elastic properties of the ground, and the large
signals we observe are in part due to the relatively soft playa sediment and
the shallow installation of the instrument. Ground tilt may be a particularly
sensitive means of detecting dust devils. The simple point-load model fails for
large dust devils at short ranges, but more elaborate models incorporating the
work of Sorrells (1971) may explain some of the more complex features in such
cases, taking the vortex winds and ground velocity into account. We discuss
some implications for the InSight mission to Mars.Comment: Contributed Article for Bulletin of the Seismological Society of
America, Accepted 29th August 201
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Reclaiming the witch: Processes and heroic outcomes of consumer mythopoesis
Although previous research has investigated consumer mythopoesis (consumers’ identity work using marketplace myths), little is known about its enactment involving ambiguous myths. Here, we investigate the myth of the witch (predominantly depicted by dominant mythmakers as a villain but recently repositioned more positively) and describe how consumers reclaim the empowering and heroic aspects of the ambiguous witch myth. Based on a qualitative study using archival data and in-depth interviews with self-proclaimed witches, we argue that the witch’s ambiguity originates in different mythopoetic cycles. Then, we describe the following processes through which consumers reclaim positive cycles: incarnating the myth, coming out to selected others and practising myth-related craft. Finally, we show that reclaiming results in new forms of heroic agency that amplify the myth’s ambiguity and identity value. Our results reveal that consumers cope with market-wide paradoxical injunctions, stressful situations and marginalisation by transforming these pressures into acts of self-heroism
Production of Sodium Bose--Einstein condensates in an optical dimple trap
We report on the realization of a sodium Bose--Einstein condensate (BEC) in a
combined red-detuned optical dipole trap, formed by two beams crossing in a
horizontal plane and a third, tightly focused dimple trap propagating
vertically. We produce a BEC in three main steps: loading of the crossed dipole
trap from laser-cooled atoms, an intermediate evaporative cooling stage which
results in efficient loading of the auxiliary dimple trap, and a final
evaporative cooling stage in the dimple trap. Our protocol is implemented in a
compact setup and allows us to reach quantum degeneracy even with relatively
modest initial atom numbers and available laser power
Solid-state laser system for laser cooling of Sodium
We demonstrate a frequency-stabilized, all-solid laser source at 589 nm with
up to 800 mW output power. The laser relies on sum-frequency generation from
two laser sources at 1064 nm and 1319 nm through a PPKTP crystal in a
doubly-resonant cavity. We obtain conversion efficiency as high as 2 W/W^2
after optimization of the cavity parameters. The output wavelength is tunable
over 60 GHz, which is sufficient to lock on the Sodium D2 line. The robustness,
beam quality, spectral narrowness and tunability of our source make it an
alternative to dye lasers for atomic physics experiments with Sodium atoms
Fractura triplana epifisaria distal de tibia: a propósito de un caso con interposición de periostio
Se presenta un caso de fractura triplana en 2 fragmentos en un paciente varón
de 13 años tratado quirúrgicamente, observando la interposición perióstica en el plano axial a
nivel del fragmento antero-externo, que impedÃa la reducción anatómica de la zona epifisaria
articular. Se analiza la anatomÃa quirúrgica de las fracturas triplanas considerando que esta lesión
puede ser más frecuente de lo que se ha informado, y sólo valorada en los casos en que se
emplee un abordaje antero-externo.The case of a 13-year-old boy with a two-fragment triplane fracture of the distal
epiphysis of the tibia is presented. At surgery, an interposition of the periosteum in the axial
plane behind the antero-lateral fragment, preventing the anatomical reduction of the epiphyseal
joint surface was found. The surgical anatomy of triplane fractures is review taking into account
that this lesion can be more frequent that it has been reported. The true incidence
should be evaluated at surgery by antero-lateral approach
Fracturas del macizo trocantéreo. Estudio comparativo Ender-DHS: revision de 114 casos
Se presenta un estudio retrospectivo de 114 fracturas pertrocantéreas tratadas
con enclavado elástico de Ender (71) y tornillo placa deslizante, DHS (43). Se efectuó un estudio
estadÃstico descriptivo-comparativo entre los 2 grupos de pacientes según la técnica quirúrgica
empleada. Se constató un mayor Ãndice de estabilidad usando el DHS (81%), frente al
6 1 % del otro grupo. La tasa de complicaciones fue del 16% y 55% respectivamente. Los resultados
clÃnicos fueron mejores en los enfermos tratados con DHS, fundamentalmente en
cuanto a la deambulación que se consiguió en el 98% (Ender 75%), ausencia de dolor y movilidad
conservada. Los autores piensan que la estabilidad preoperatoria no influye en la solidez
del montaje usando el DHS, pero con la técnica de Ender ésta disminuye en las fracturas inestables;
por ello, la técnica de Ender estarÃa solamente indicada en el tratamiento de fracturas
estables en pacientes de edad avanzada o con mal estado general, aunque en clara competencia
con el DHS.A retrospective study of 114 intertrochanteric fractures operated on either with
Ender's rods (71) or dynamic hip screws, DHS (43) is presented. A statistical descriptive-comparative
study between the 2 groups was attempted. There was a greater index of stability using the
DHS (82%) than Ender's rods (61%). The rate of complications was 16% and 55% respectively.
The clinical outcome was better in cases treated with DHS, specially for walking ability,
which was regained in the 98% of cases (Ender 75%), painless and preserved mobility. The authors
think that the stability before operation do not influence the solidity of the assembly using
the DHS device. On the contrary, with the Ender's technique the fixation is no satisfactory in
unstables fractures. Ender's rods would only be suitable for treatment of stable fractures in older
patient or with serious associated diseases, although in clear competition with the DHS
Seismic risk in the city of Al Hoceima (north of Morocco) using the vulnerability index method, applied in Risk-UE project
The final publication is available at Springer via http://dx.doi.org/10.1007/s11069-016-2566-8Al Hoceima is one of the most seismic active regions in north of Morocco. It is demonstrated by the large seismic episodes reported in seismic catalogs and research studies. However, seismic risk is relatively high due to vulnerable buildings that are either old or don’t respect seismic standards. Our aim is to present a study about seismic risk and seismic scenarios for the city of Al Hoceima. The seismic vulnerability of the existing residential buildings was evaluated using the vulnerability index method (Risk-UE). It was chosen to be adapted and applied to the Moroccan constructions for its practicality and simple methodology. A visual inspection of 1102 buildings was carried out to assess the vulnerability factors. As for seismic hazard, it was evaluated in terms of macroseismic intensity for two scenarios (a deterministic and probabilistic scenario). The maps of seismic risk are represented by direct damage on buildings, damage to population and economic cost. According to the results, the main vulnerability index of the city is equal to 0.49 and the seismic risk is estimated as Slight (main damage grade equal to 0.9 for the deterministic scenario and 0.7 for the probabilistic scenario). However, Moderate to heavy damage is expected in areas located in the newer extensions, in both the east and west of the city. Important economic losses and damage to the population are expected in these areas as well. The maps elaborated can be a potential guide to the decision making in the field of seismic risk prevention and mitigation strategies in Al Hoceima.Peer ReviewedPostprint (author's final draft
Une méthode adaptative pour la segmentation de drusen
Le but de ce travail est la segmentation automatique d'images d'angiographie du fond de l'oeil pour extraire les drusen, qui sont des taches jaunes, un peu nuageuses situées au niveau de la rétine. Les méthodes classiques de segmentation n'étant pas efficaces pour l'extraction automatique des drusen, nous introduisons une nouvelle approche adaptative. Nous introduisons un algorithme adaptatif basé sur des transformations issues de la morphologie mathématique. Au calcul de la transformée "maxima h - ∞", nous proposons une définition automatique du paramètre de contraste h. Nous introduisons également une approche avec une fonction h(x) non constante. Le résultat ainsi obtenu fait ressortir les taches en uniformisant le fond. Notre méthode donne des résultats très satisfaisants sur des images typiques
The linear ubiquitin chain assembly complex regulates TRAIL-induced gene activation and cell death.
The linear ubiquitin chain assembly complex (LUBAC) is the only known E3 ubiquitin ligase which catalyses the generation of linear ubiquitin linkages de novo LUBAC is a crucial component of various immune receptor signalling pathways. Here, we show that LUBAC forms part of the TRAIL-R-associated complex I as well as of the cytoplasmic TRAIL-induced complex II In both of these complexes, HOIP limits caspase-8 activity and, consequently, apoptosis whilst being itself cleaved in a caspase-8-dependent manner. Yet, by limiting the formation of a RIPK1/RIPK3/MLKL-containing complex, LUBAC also restricts TRAIL-induced necroptosis. We identify RIPK1 and caspase-8 as linearly ubiquitinated targets of LUBAC following TRAIL stimulation. Contrary to its role in preventing TRAIL-induced RIPK1-independent apoptosis, HOIP presence, but not its activity, is required for preventing necroptosis. By promoting recruitment of the IKK complex to complex I, LUBAC also promotes TRAIL-induced activation of NF-κB and, consequently, the production of cytokines, downstream of FADD, caspase-8 and cIAP1/2. Hence, LUBAC controls the TRAIL signalling outcome from complex I and II, two platforms which both trigger cell death and gene activation
The Mars Microphone onboard SuperCam
The Mars Microphone is one of the five measurement techniques of SuperCam, an
improved version of the ChemCam instrument that has been functioning aboard the
Curiosity rover for several years. SuperCam is located on the Rover's Mast
Unit, to take advantage of the unique pointing capabilities of the rover's
head. In addition to being the first instrument to record sounds on Mars, the
SuperCam Microphone can address several original scientific objectives: the
study of sound associated with laser impacts on Martian rocks to better
understand their mechanical properties, the improvement of our knowledge of
atmospheric phenomena at the surface of Mars: atmospheric turbulence,
convective vortices, dust lifting processes and wind interactions with the
rover itself. The microphone will also help our understanding of the sound
signature of the different movements of the rover: operations of the robotic
arm and the mast, driving on the rough floor of Mars, monitoring of the pumps,
etc ... The SuperCam Microphone was delivered to the SuperCam team in early
2019 and integrated at the Jet Propulsion Laboratory (JPL, Pasadena, CA) with
the complete SuperCam instrument. The Mars 2020 Mission launched in July 2020
and landed on Mars on February 18th 2021. The mission operations are expected
to last until at least August 2023. The microphone is operating perfectly.Comment: 40 page
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