Copepods encounter rates from a model of escape jump behaviour in turbulence

A key ecological parameter for planktonic copepods studies is their interspecies encounter rate which is driven by their behaviour and is strongly influenced by turbulence of the surrounding environment. A distinctive feature of copepods motility is their ability to perform quick displacements, often dubbed jumps, by means of powerful swimming strokes. Such a reaction has been associated to an escape behaviour from flow disturbances due to predators or other external dangers. In the present study, the encounter rate of copepods in a developed turbulent flow with intensity comparable to the one found in copepods' habitat is numerically investigated. This is done by means of a Lagrangian copepod (LC) model that mimics the jump escape reaction behaviour from localised high-shear rate fluctuations in the turbulent flows. Our analysis shows that the encounter rate for copepods of typical perception radius of ~ {\eta}, where {\eta} is the dissipative scale of turbulence, can be increased by a factor up to ~ 100 compared to the one experienced by passively transported fluid tracers. Furthermore, we address the effect of introducing in the LC model a minimal waiting time between consecutive jumps. It is shown that any encounter-rate enhancement is lost if such time goes beyond the dissipative time-scale of turbulence, {\tau}_{\eta}. Because typically in the ocean {\eta} ~ 0.001m and {\tau}_{\eta} ~ 1s, this provides stringent constraints on the turbulent-driven enhancement of encounter-rate due to a purely mechanical induced escape reaction.Comment: 11 pages, 10 figure

Ocean Wind Energy Technologies in Modern Electric Networks: Opportunity and Challenges

Wind energy is one of the most important sources of energy in the world. In recent decades, wind as one of the massive marine energy resources in the ocean to produce electricity has been used. This chapter introduces a comprehensive overview of the efficient ocean wind energy technologies, and the global wind energies in both offshore and onshore sides are discussed. Also, the classification of global ocean wind energy resources is presented. Moreover, different components of a wind farm offshore as well as the technologies used in them are investigated. Possible layouts regarding the foundation of an offshore wind turbine, floating offshore, as well as the operation of wind farms in the shallow and deep location of the ocean are studied. Finally, the offshore wind power plant challenges are described

Cerebral cavernous malformations proteins inhibit Rho kinase to stabilize vascular integrity

Endothelial cell–cell junctions regulate vascular permeability, vasculogenesis, and angiogenesis. Familial cerebral cavernous malformations (CCMs) in humans result from mutations of CCM2 (malcavernin, OSM, MGC4607), PDCD10 (CCM3), or KRIT1 (CCM1), a Rap1 effector which stabilizes endothelial cell–cell junctions. Homozygous loss of KRIT1 or CCM2 produces lethal vascular phenotypes in mice and zebrafish. We report that the physical interaction of KRIT1 and CCM2 proteins is required for endothelial cell–cell junctional localization, and lack of either protein destabilizes barrier function by sustaining activity of RhoA and its effector Rho kinase (ROCK). Protein haploinsufficient Krit1+/− or Ccm2+/− mouse endothelial cells manifested increased monolayer permeability in vitro, and both Krit1+/− and Ccm2+/− mice exhibited increased vascular leak in vivo, reversible by fasudil, a ROCK inhibitor. Furthermore, we show that ROCK hyperactivity occurs in sporadic and familial human CCM endothelium as judged by increased phosphorylation of myosin light chain. These data establish that KRIT1–CCM2 interaction regulates vascular barrier function by suppressing Rho/ROCK signaling and that this pathway is dysregulated in human CCM endothelium, and they suggest that fasudil could ameliorate both CCM disease and vascular leak

Copepods encounter rates from a model of escape jump behaviour in turbulence

\u3cp\u3eA key ecological parameter for planktonic copepod studies is their encounter rates within the same population as well as with other species. The encounter rate is partly determined by copepod's swimming behaviour and is strongly influenced by turbulence of the surrounding environment. A distinctive feature of copepods' motility is their ability to perform quick displacements, often termed jumps, by means of powerful swimming strokes. Such a reaction has been associated to an escape behaviour from flow disturbances due to predators or other external signals. In the present study, we investigate the encounter rates of copepods of the same species in a developed turbulent flow with intensities comparable to those encountered in their natural habitat. This is done by means of a Lagrangian copepod (LC) model that mimics the jump escape reaction behaviour from localized high-deformation rate fluctuations in the turbulent flows. Our analysis shows that the encounter rate for copepods of typical perception radius of ∼, where is the dissipative scale of turbulence, can be increased by a factor up to ∼102 compared to that experienced by passively transported fluid tracers of the same size. Furthermore, we address the effect of a minimal waiting time between consecutive jumps. It is shown that any encounter-rate enhancement is lost if such time goes beyond the dissipative time-scale of turbulence, Because typically in the ocean ∼1mm and, ∼1s, this provides stringent constraints on the turbulent-driven enhancement of contact-rate due to a purely mechanical induced escape reaction. The implications of our results in the context of copepod ecology copepods are discussed.\u3c/p\u3

Factor XI deficiency in Southern Iran: identification of a novel missense mutation

Factor XI (FXI)-deficiency is a rare coagulation disorder inherited as an autosomal recessive trait, which is most common in Ashkenazi Jews, but also found in other groups like Moslems. We have reviewed for the first time cases of FXI deficiency in southern Iran in order to analyze their mutations related to factor XI, the main clinical and biological features, levels of circulating factor XI, and bleeding history. All 15 exons and exon-intron boundaries of F11 were polymerase chain reaction amplified using sets of primers designed on the basis of the known genomic sequence of the gene. Among bleeding disorder cases, five were FXI-deficient. FXI clotting activity ranged 0.39-16%. All were severely deficient. In all analyzed patients, functional level of FXI was markedly reduced, confirming the diagnosis of quantitative FXI deficiency. Sequencing of F11 identified three mutations: (1) a highly prevalent type II nonsense mutation (Glu117stop) in a homozygous patient, (2) a previously reported missense (Glu547Lys), and (3) novel missense (Gly372Ala) mutation. No causative mutation was found in the sequenced regions of other patients. One novel mutation and two previously described mutations were identified in patients living in southern Iran. No recurrent mutation was found, perhaps because there is a more intense population mixing in southern Iran. Screening a higher number of FXI-deficient patients will also be necessary to reveal the existence of a founder effect for these mutations in the Iranian population

Efficacy of prophylaxis and genotype-phenotype correlation in patients with severe Factor X deficiency in Iran

We aimed to evaluate the effect of regular prophylaxis with a Factor X (FX) concentrate for patients with severe FXD in Iran and to assess the correlation of the genotype and phenotype in these patients. Ten patients with severe FXD (FX activity <1%) were enrolled and characterized during 2010-2011. Prophylaxis with 20\u2003IU FX P Behring per kg body weight was administered once a week. FX levels, were monitored at baseline, 15 and 30\u2003min, 1, 3, 6, 12, 24, 48, 72 and 96\u2003h after starting prophylaxis. All patients were followed for 1\u2003year. The mean age of the patients was 15\u2003\ub1\u20037.8\u2003years (age range of: 6-27\u2003years). One patient had anaphylactic reaction after the first infusion, and the treatment was stopped. During one-year follow-up after starting prophylaxis, no bleeding symptoms occurred in any patient who tolerated and remained on the prophylaxis programme and all of them had a FX level of 1% or above. The maximum level of FX activity has been observed at 15\u2003min after starting prophylaxis. A level of 1.5-3.5% was detected after 96\u2003h. Homozygous mutations p.Arg40Thr (Arg-1Thr), p.Gly51Arg and p.Glu69Lys were detected in patients with intracranial haemorrhage. In our patients, significant decrease in symptoms without any complication after administration of FX, was demonstrated in all except one patient who had an anaphylactic reaction. It seems that the dose of 20\u2003IU\u2003kg(-1) could be probably the best choice for patients with severe FXD, who require regular prophylaxi

Observation of turbulent dispersion of artificially released SO₂ puffs with UV cameras

In atmospheric tracer experiments, a substance is released into the turbulent atmospheric flow to study the dispersion parameters of the atmosphere. That can be done by observing the substance's concentration distribution downwind of the source. Past experiments have suffered from the fact that observations were only made at a few discrete locations and/or at low time resolution. The Comtessa project (Camera Observation and Modelling of 4-D Tracer Dispersion in the Atmosphere) is the first attempt at using ultraviolet (UV) camera observations to sample the three-dimensional (3-D) concentration distribution in the atmospheric boundary layer at high spatial and temporal resolution. For this, during a three-week campaign in Norway in July 2017, sulfur dioxide (SO2), a nearly passive tracer, was artificially released in continuous plumes and nearly instantaneous puffs from a 9&thinsp;m high tower. Column-integrated SO2 concentrations were observed with six UV SO2 cameras with sampling rates of several hertz and a spatial resolution of a few centimetres. The atmospheric flow was characterised by eddy covariance measurements of heat and momentum fluxes at the release mast and two additional towers. By measuring simultaneously with six UV cameras positioned in a half circle around the release point, we could collect a data set of spatially and temporally resolved tracer column densities from six different directions, allowing a tomographic reconstruction of the 3-D concentration field. However, due to unfavourable cloudy conditions on all measurement days and their restrictive effect on the SO2 camera technique, the presented data set is limited to case studies. In this paper, we present a feasibility study demonstrating that the turbulent dispersion parameters can be retrieved from images of artificially released puffs, although the presented data set does not allow for an in-depth analysis of the obtained parameters. The 3-D trajectories of the centre of mass of the puffs were reconstructed enabling both a direct determination of the centre of mass meandering and a scaling of the image pixel dimension to the position of the puff. The latter made it possible to retrieve the temporal evolution of the puff spread projected to the image plane. The puff spread is a direct measure of the relative dispersion process. Combining meandering and relative dispersion, the absolute dispersion could be retrieved. The turbulent dispersion in the vertical is then used to estimate the effective source size, source timescale and the Lagrangian integral time. In principle, the Richardson–Obukhov constant of relative dispersion in the inertial subrange could be also obtained, but the observation time was not sufficiently long in comparison to the source timescale to allow an observation of this dispersion range. While the feasibility of the methodology to measure turbulent dispersion could be demonstrated, a larger data set with a larger number of cloud-free puff releases and longer observation times of each puff will be recorded in future studies to give a solid estimate for the turbulent dispersion under a variety of stability conditions.</p