Tumbling under the surf Navarrete, S. A.; Largier, J. L.; Vera, G. ...
Marine ecology. Progress series (Halstenbek),
02/2015, Letnik:
520
Journal Article
Recenzirano
Odprti dostop
For many mussel species, the model of planktonic development followed by metamorphosis and settlement in the benthic habitat is complicated by the existence of planktonic post-metamorphic stages ...and/or pediveliger benthic stages that can relocate after initial settlement. This has led to the long-standing hypothesis of ‘primary’ settlement from the plankton onto intertidal algal substrate followed by ‘secondary’ relocation to mussel beds. Here, we investigate settlement of the intertidal mussels Perumytilus purpuratus and Semimytilus algosus in central Chile to test this hypothesis and explore physical drivers. Our results indicate that: (1) these species do not have planktonic post-metamorphic stages, (2) larvae typically arrive to the intertidal zone at a size 80–150 μm larger than the largest planktonic larva, which based on growth rates, corresponds to a 3–20 d delay, (3) there are no differences in pediveliger sizes between different algal substrates, mussel beds, or artificial collectors, and (4) there is no evidence that larvae metamorphose in the intertidal and grow in alternative habitat before relocation to mussel beds. In 2 summers, daily settlement of both species was tightly and positively associated with wave height, despite large inter-annual variability in wind conditions. Our results reject the primary-secondary settlement hypothesis and support a new settlement model in which, after metamorphosis beyond the surf zone, the negatively buoyant settlers become semi-benthic and readily sink to the bottom. There, they can be transported onshore through the surf-zone by wave-driven near-bed transport. The process of tumbling under the surf may take from a few hours to several days, with larvae arriving at the shoreline in a wide range of sizes at any given time. For some larvae, relocation continues in the intertidal zone for months.
In recent years, a class of soft (deformable) robots has attracted the attention of researchers due to their continuum features being advantageous over rigid robots for dexterous and safe compliant ...motions. These distinct advantages are obtained from the elastomer hyperelastic material properties because continuum robots are manufactured and actuated through embedded pneumatic energy fields. In this way, the continuum deformation raises novel problems in modeling and control due to its highly nonlinear behavior. That is, the deformable shape of its components varies continuously, unlike rigid robots, suggesting that the controller should compensate for its varying continuum model. Motivated by the deformable soft robot subject to parametric uncertainties and unmodeled dynamics, this paper proposes an adaptive, instead of constant, tuning of feedback gains of a model-free controller. The tuning mechanism is based on a knowledge-based scheme using a discrete wavelet neural network (DWN) by an efficient input–output identification updating its parameters and weights online, with a gradient descent algorithm driven by the identification error. At the same time, the control feedback gains are self-tuned, minimizing a convex cost function of tracking errors. Dynamic simulations show the performance of the proposed approach considering the parameters of a real soft robot mimicking a gelatin-like behavior. Finally, some discussions on the proposed scheme’s computational cost, feasibility, and viability are briefly addressed.
In this radiation tolerance study, Low Gain Avalanche Detectors (LGADs) with a carbon-enriched broad and shallow multiplication layer were examined in comparison to identical non-carbonated LGADs. ...Manufactured at IMB-CNM, the sensors underwent neutron irradiation at the TRIGA reactor in Ljubljana, reaching a fluence of \(1.5e^{15} {n_{eq}} cm^{-2}\). The results revealed a smaller deactivation of boron and improved resistance to radiation in carbonated LGADs. The study demonstrated the potential benefits of carbon enrichment in mitigating radiation damage effects, particularly the acceptor removal mechanism, reducing the acceptor removal constant by more than a factor of two. Additionally, time resolution and collected charge degradation due to irradiation were observed, with carbonated samples exhibiting better radiation tolerance. A noise analysis focused on baseline noise and spurious pulses showed the presence of thermal-generated dark counts attributed to a too narrow distance between the gain layer end and the p-stop implant at the periphery of the pad for the characterized LGAD design; however, without significant impact of operation performance.
In order to control the grain size by the addition of microalloying elements, it is important to realize that the sequence of casting, reheating, control rolling and subsequent weld cycles may ...produce a complex series of precipitation reactions. To characterize these reactions in a quantitative manner, it is essential to attempt to define the structure, morphology, composition, size and distribution of precipitate phases produced during the thermal processes. The role of precipitate particles is to refine austenite grains by the pinning of the boundaries during normalizing heat treatments or during thermomechanical working, and to harden the ferrite grains on cooling after transformation. The goal of present work is to characterize chemically, structurally and microstructurally the precipitate phases formed in a Nb-containing microalloyed steel during isothermal aging by means of X-ray diffraction (XRD), scanning and transmission electron microscopes (SEM and TEM) and EDS microanalysis.
Deep brain stimulation (DBS) is a surgical technique based on the placement of a programmable electrode into certain areas of central nervous system. DBS is nowadays a well established treatment for ...patients with Parkinson's disease (PD) and motor complications. However, there are controversies about several items, including the correct selection of patients and the best time for DBS. There is a current trend for DBS to be carried out at earlier stages of PD. A group of experts from Spanish Neurosurgical Society (Functional Surgery Study Group) and Spanish Neurological Society (Movement Disorders Study Group) wrote this consensus statement in order to clarify these and other items.
ABSTRACT
Recent wide-area surveys have enabled us to study the Milky Way with unprecedented detail. Its inner regions, hidden behind dust and gas, have been partially unveiled with the arrival of ...near-infrared (IR) photometric and spectroscopic data sets. Among recent discoveries, there is a population of low-mass globular clusters, known to be missing, especially towards the Galactic bulge. In this work, five new low-luminosity globular clusters located towards the bulge area are presented. They were discovered by searching for groups in the multidimensional space of coordinates, colours, and proper motions from the Gaia EDR3 catalogue and later confirmed with deeper VVV survey near-IR photometry. The clusters show well-defined red giant branches and, in some cases, horizontal branches with their members forming a dynamically coherent structure in proper motion space. Four of them were confirmed by spectroscopic follow-up with the MUSE instrument on the ESO VLT. Photometric parameters were derived, and when available, metallicities, radial velocities, and orbits were determined. The new clusters Gran 1 and 5 are bulge globular clusters, while Gran 2, 3 and 4 present halo-like properties. Preliminary orbits indicate that Gran 1 might be related to the Main Progenitor, or the so-called ‘low-energy’ group, while Gran 2, 3 and 5 appears to follow the Gaia-Enceladus/Sausage structure. This study demonstrates that the Gaia proper motions, combined with the spectroscopic follow-up and colour–magnitude diagrams, are required to confirm the nature of cluster candidates towards the inner Galaxy. High stellar crowding and differential extinction may hide other low-luminosity clusters.
This article describes a bibliometric review of the publications on obesity research in PubMed over the last 20 years. We used Medline via the PubMed online service of the US National Library of ...Medicine from 1988 to 2007. The search strategy was: (obesity in MesH). A total of 58 325 references were retrieved, 25.5% in 1988-1997, and 74.5% in 1998-2007. The growth in the number of publications showed an exponential increase. The references were published in 3613 different journals, with 20 journals contributing 25% of obesity literature. The two journals contributing most were the International Journal of Obesity (5.1%), Obesity-Obesity Research (2.9%). North America and Europe were the most productive world areas with 44.1% and 37.9% of the literature, respectively. The US was the predominant country in number of publications, followed by the United Kingdom, Japan and Italy. The ranking of production changed when the number of publications was normalized by population, gross domestic product and obesity prevalence by countries. The great increase of publications on obesity during the period 1988-2007 was particularly evident in the second decade of the period which is concordant with the worldwide obesity epidemic. USA and Europe were leaders in the production of scientific articles on obesity.
The prototypical second messenger cAMP regulates a wide variety of physiological processes. It can simultaneously mediate diverse functions by acting locally in independently regulated microdomains. ...In mammalian cells, two types of adenylyl cyclase generate cAMP: G-protein-regulated transmembrane adenylyl cyclases and bicarbonate-, calcium- and ATP-regulated soluble adenylyl cyclase (sAC). Because each type of cyclase regulates distinct microdomains, methods to distinguish between them are needed to understand cAMP signaling. We developed a mass-spectrometry-based adenylyl cyclase assay, which we used to identify a new sAC-specific inhibitor, LRE1. LRE1 bound to the bicarbonate activator binding site and inhibited sAC via a unique allosteric mechanism. LRE1 prevented sAC-dependent processes in cellular and physiological systems, and it will facilitate exploration of the therapeutic potential of sAC inhibition.
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