318 research outputs found
Rapid absolute plate motion changes inferred from high-resolution relative spreading reconstructions: A case study focusing on the South America plate and its Atlantic/Pacific neighbors
The reconstruction of past plate motions relative to a deemed–to–be–fixed hotspot reference frame relies on the sparse occurrence of intraplate volcanism. Consequently, this absolute reference frame often features a temporal resolution that exceeds the rapid kinematic changes observed in plate–to–plate spreading reconstructions, changes recently shown to occur within less than 5 Ma. In this work we put forward an alternative method based on the study of high–resolution relative plate motion data sets. By studying time periods featuring a relatively high probability of plate motion change across multiple spreading ridges, we are able to identify and quantify (likely) changes in absolute plate motion. Specifically, we implement such approach and provide well–defined estimates for the absolute plate motion changes of South America and neighboring plates Nubia, Antarctica, Somalia, North America and Pacific. We find that kinematic changes for all these plates occur between 9 and 5 Ma. For South America, we identify a change also between 14 and 10 Ma. Lastly, we estimate the torque–variations required upon these plates to generate the inferred kinematic changes, which we find to be between ∼5⋅1023 and ∼20⋅1024 N ⋅ m
Experimental and theoretical memory diffusion of water in sand
International audienceThe basic equations used to study the fluid diffusion in porous media have been set by Fick and Darcy in the mid of the XIXth century but some data on the flow of fluids in rocks exhibit properties which may not be interpreted with the classical theory of propagation of pressure and fluids in porous media (Bell and Nur, 1978; Roeloffs, 1988). Concerning the fluids and the flow, some fluids carry solid particles which may obstruct some of the pores diminishing their size or even closing them, some others may chemically and physically react with the medium enlarging the pores; so permeability changes during time and the flow occurs as if the medium had a memory. In this paper we show with experimental data that the permeability of sand layers may decrease due to rearrangement of the grains and consequent compaction, as already shown qualitatively by Elias and Hajash (1992). We also provide a memory model for diffusion of fluids in porous media which fits well the flux rate observed in five laboratory experiments of diffusion of water in sand. Finally we show that the flux rate variations observed during the experiments are compatible with the compaction of sand, due to the amount of fluid which went through the grains locally, and therefore with the reduction of porosity
Role of mantle flow in Nubia-Somalia plate divergence
Present-day continental extension along the East African Rift System (EARS) has often been attributed to diverging sublithospheric mantle flow associated with the African Superplume. This implies a degree of viscous coupling between mantle and lithosphere that remains poorly constrained. Recent advances in estimating present-day opening rates along the EARS from geodesy offer an opportunity to address this issue with geodynamic modeling of the mantle-lithosphere system. Here we use numerical models of the global mantle-plates coupled system to test the role of present-day mantle flow in Nubia-Somalia plate divergence across the EARS. The scenario yielding the best fit to geodetic observations is one where torques associated with gradients of gravitational potential energy stored in the African highlands are resisted by weak continental faults and mantle basal drag. These results suggest that shear tractions from diverging mantle flow play a minor role in present-day Nubia-Somalia divergence.This work was supported by NSF award EAR-0538119 to E.C. D.S.S. was supported by NSF graduate research fellowship EAR-2009052513. G.I. acknowledges support from the
Ringwood Fellowship at the Australian National University
The use of alternative energies in hatcheries: an application of Life Cycle Analysis
Fish production requires great efforts and energies and causes different impacts/effects on the ecosystems. The development of aquaculture is possible, in the medium and long term, only if this is done responsibly, and if the production is reached from both an economic and environmental point of view. In our study we have worked on fry production using 1.5 g sized Dicentrarchus labrax obtained rearing larvae for 120 days after the hatching of the eggs
Neuromyelitis optica spectrum disorders associated with systemic sclerosis: a case report and literature review
Neuromyelitis optica (NMO) is an autoimmune demyelinating disease of the central nervous system (CNS) afecting
predominantly the spinal cord, brainstem, and optic nerves
[1]. NMOSD may be associated with a variety of immunemediated disorders, such as systemic lupus erythematosus,
Sjögren syndrome, and other organ-specifc autoimmune
diseases [2], though accurate information about their prevalence is not available [3]. Systemic sclerosis (SSc) is characterized by vascular alterations, activation of the immune
system, and tissue fbrosis [4]. Only a few cases of coexisting
systemic sclerosis (SSc) and NMOSD are described [1, 5–9].
We report a case of an NMOSD AQP4-IgG antibodypositive patient associated with SSc and a review of the
available evidence of the relationship between these autoimmune disease
Free-Range Rearing Density for Male and Female Milanino Chickens: Growth Performance and Stress Markers
The Milanino is a heavy Italian chicken breed and represents an important genetic resource for alternative production systems. Due to the absence of standard management guidelines for local chicken breeds, this study aims to determine the space requirement to achieve a good equilibrium between growth performance and stress response in Milanino chickens reared according to a separate-sex free-range program. A total of 140 birds (70M:70F) were reared in outdoor pens from 75 to 235 d of life according to the following experimental groups (35 birds/group): (M2) males in 2 m(2)/bird; (F2) females in 2 m(2)/bird; (M10) males in 10 m(2)/bird; (F10) females in 10 m(2)/bird. Growth performance and stress condition were recorded. Bird density affected male body weight, that was higher at the lower density of 10 m2/bird. In contrast, females showed a consistent growth rate irrespective of the bird density suggesting lower space requirements. An overall good adaptability of the breed to the separate-sex free-range system was found, irrespective of both sex and bird density. Moreover, the stress markers values assessed at the end of the growing period suggest the ability of Milanino birds to respond well to environmental stressors. The results provided in this report will be implemented into free-range management guidelines for meat production in the Milanino breed: the separate-sex rearing is recommended during the growing period in outdoor pens and the bird density has to be planned according to the sex
Finding an effective freezing protocol for Turkey semen: Benefits of ficoll as non-permeant cryoprotectant and 1:4 as dilution rate
The present study aimed to find an effective cryopreservation protocol for turkey semen through the combined use of dimethylsulfoxide (DMSO) and three non-permeant cryoprotectants (NP-CPAs), sucrose, trehalose, and Ficoll 70. In addition, the action of two dilution rates (1:2 and 1:4) were also investigated. Semen was processed according to two final dilution rates and the following treatments: Tselutin extender (TE)/DMSO (control), TE/DMSO + sucrose or trehalose 50, 100, 200, or 400 mM, and TE/DMSO + Ficoll 0.5, 0.75, 1, or 1.5 mM. In total 26 different combinations treatments were achieved. The diluted semen was filled up into straws and frozen on liquid nitrogen vapor. The post-thawing sperm quality was assessed by analyzing motility, membrane integrity, osmotic resistance, and DNA integrity. The results obtained revealed a significant effect of NP-CPA concentration on total and progressive motility, on most of the kinetic parameters, on membrane integrity and DNA integrity, while the post-thaw quality was less affected by dilution rate. The highest post-thaw quality for all sperm quality parameters assessed except curvilinear velocity (VCL) and DNA integrity were found in semen frozen with 1 mM Ficoll/1:4 (p < 0.05). Our findings provide an important contribution for the identification of a reference procedure for turkey semen cryopreservation, in order to create the first national avian semen cryobank
Validation of the Turkey semen cryopreservation by evaluating the effect of two diluents and the inseminating doses
This study was designed to test the fertilizing ability of cryopreserved turkey semen, and here, two experiments were performed: an in vitro analysis to assess the effects of Tselutin and Lake diluents and an in vivo test to determine the fertility and hatching rates by also studying the feat of three insemination doses (250, 400 and 600
7 106 sperm/hen). Pooled semen samples were diluted with Tselutin or Lake extender which contained 20% of dimethylsulfoxide and 1 mM of Ficoll at final sperm concentration of 3
7 109 sperm/mL. Thereafter, semen was packaged into straws and frozen on liquid nitrogen. The post-thaw sperm quality was evaluated considering motility (computer-aided sperm analysis\u2014CASA system) and membrane integrity (flow cytometry). Significantly higher values of progressive motility and some kinetic parameters in semen frozen with Lake were found. When we compared the extenders in vivo, no significant effects were detected, whilst sperm concentration significantly affected both fertility and hatching rates, with the best results obtained with the sperm concentration of 400
7 106 sperm/hen. From the results obtained, it emerged that the extender type only affected sperm motility characteristics, not the fertilizing ability of frozen-thawed semen, while inseminating dose markedly affected fertility and hatching rates
Predictors of unemployment status in people with relapsing multiple sclerosis: a single center experience
Background: Multiple sclerosis (MS) is the most common cause of nontraumatic chronic neurological disability affecting young adults during their crucial employment years. Objectives: To evaluate patients and disease related factors associated to unemployment in a cohort of relapsing–remitting (RR) MS patients. Methods: We included RRMS patients with a follow-up of at least 1 year. We collected data about years of school education and employment status. Patients underwent a neuropsychological evaluation using the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS). Demographic and clinical predictors of unemployment were assessed through a multivariable stepwise logistic regression model. Results: We evaluated 260 consecutive RRMS patients. Employed patients were less frequently female (68.4% vs 83.3%, p = 0.006), less disabled (median Expanded Disability Status Scale (EDSS) score: 2.0 (0–7.0) vs 2.5 (0–7.5), p < 0.001), with more years of school education (mean ± standard deviation (SD), years: 13.74 ± 0.30 vs 10.86 ± 3.47, p < 0.001). Female sex and a higher EDSS score resulted associated with a greater risk of unemployment (OR 3.510, 95% CI 1.654–7.448, p = 0.001; OR 1.366, 95% CI 1.074–1.737, p = 0.011, respectively), whereas a greater number of years of schooling and current disease-modifying therapy exposure resulted protective factors (OR 0.788, 95% CI 0.723–0.858, p < 0,001; OR 0.414, 95% CI 0.217–0.790, p = 0.008, respectively). Conclusions: Understanding work is pervasively influenced by consequences of MS, we confirmed the impact of demographic, physical, and cognitive factors on employment status in RRMS patients
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