The issue of outwelling in the Guadiana River estuary (Portugal): some findings and research suggestions in the context of recent evidence

Abstract The ‘‘Outwelling Theory’’ states that salt marshes play a major role in exporting production to adjacent estuarine and coastal ecosystems. However, it has been found that some marshes act as net importers instead of net exporters of organic matter and nutrients. Once we include mangroves and refine the analysis to comprehend bacterioplankton, organic and stable isotope tracers, the picture became, more complex, making room for a revival of the outwelling idea. The exchanges between the Castro Marim salt marsh and the main estuary were tentatively established determining periodically, in a selected cross-section, the concentrations of TSS, FSS, VSS, NH4, NO2, NO3, NKjeldhal, SiO4, PO4, TDP, Chlorophyll a and Pheopigments, measuring their fluxes along tidal cycles and computing the corresponding budgets. Apparently, the sedimentary behaviour of the marsh will be close to equilibrium during the period of study. However, it will import mainly inert matter and export mainly organic matter in the same period. Moreover, extrapolating these results to the entire Guadiana salt marshes, the exchanges of sediment do not seem to be significant. Particularly, the marshes will not trap a significantly amount sediment transported by the main river (0.5%). It also seems to follow, that in a general way, the Guadiana salt marshes might have a more significant role than was anticipated in the system economy ofOMand nutrients and their outwelling to coastal waters, assuring outputs that could amount to something like 6% of the river load of N, 1.2% of the river load of P, and 20-57% of the river load of TOC, for an average year, and 42% of the river load of Nand 35% of the river load of P in a dry year. These findings suggest that a more detailed investigation, over an extended period of time, is certainly worthwhile

PLK4 trans-Autoactivation Controls Centriole Biogenesis in Space

The deposited article is a post-print version and has been submitted to peer review.This publication hasn't any creative commons license associated.The deposited article version contains attached the supplementary materials within the pdf.Centrioles are essential for cilia and centrosome assembly. In centriole-containing cells, centrioles always form juxtaposed to pre-existing ones, motivating a century-old debate on centriole biogenesis control. Here, we show that trans-autoactivation of Polo-like kinase 4 (PLK4), the trigger of centriole biogenesis, is a critical event in the spatial control of that process. We demonstrate that centrioles promote PLK4 activation through its recruitment and local accumulation. Though centriole removal reduces the proportion of active PLK4, this is rescued by concentrating PLK4 to the peroxisome lumen. Moreover, while mild overexpression of PLK4 only triggers centriole amplification at the existing centriole, higher PLK4 levels trigger both centriolar and cytoplasmatic (de novo) biogenesis. Hence, centrioles promote their assembly locally and disfavor de novo synthesis. Similar mechanisms enforcing the local concentration and/or activity of other centriole components are likely to contribute to the spatial control of centriole biogenesis under physiological conditions.Fundação Portuguesa para a Ciência e Tecnologia grants: (SFRH/BPD/87479/2012, PTDC/BBB-BEP/1724/2012, HMSP-CT/SAU-ICT/0075/2009, PTDC/SAU-OBD/105616/2008, EXPL/BIM-ONC/0830/2013, PTDC/BBB-BEP/1724/2012); EMBO installation grant; ERC starting grant: (PFE-GI-UE-ERC-2010-StG-261344).info:eu-repo/semantics/publishedVersio

The role of point-like topological excitations at criticality: from vortices to global monopoles

We determine the detailed thermodynamic behavior of vortices in the O(2) scalar model in 2D and of global monopoles in the O(3) model in 3D. We construct new numerical techniques, based on cluster decomposition algorithms, to analyze the point defect configurations. We find that these criteria produce results for the Kosterlitz-Thouless temperature in agreement with a topological transition between a polarizable insulator and a conductor, at which free topological charges appear in the system. For global monopoles we find no pair unbinding transition. Instead a transition to a dense state where pairs are no longer distinguishable occurs at T<Tc, without leading to long range disorder. We produce both extensive numerical evidence of this behavior as well as a semi-analytic treatment of the partition function for defects. General expectations for N=D>3 are drawn, based on the observed behavior.Comment: 14 pages, REVTEX, 13 eps figure

Measuring Cosmic Defect Correlations in Liquid Crystals

From the theory of topological defect formation proposed for the early universe, the so called Kibble mechanism, it follows that the density correlation functions of defects and anti-defects in a given system should be completely determined in terms of a single length scale $\xi$, the relevant domain size. Thus, when lengths are expressed in units of $\xi$, these distributions should show universal behavior, depending only on the symmetry of the order parameter, and space dimensions. We have verified this prediction by analyzing the distributions of defects/anti-defects formed in the isotropic-nematic phase transition in a thin layer of nematic liquid crystals. Our experimental results confirm this prediction and are in reasonable agreement with the results of numerical simulations.Comment: 15 pages, 4 figures, minor changes, few new references adde

Centrosome amplification arises before neoplasia and increases upon p53 loss in tumorigenesis

The uploaded article version is the Epub Ahead of Print version of the article, posted online 8 May 2018. It has been submitted to peer-review.The deposited article version contains attached the supplementary materials within the pdf.Centrosome abnormalities are a typical hallmark of human cancers. However, the origin and dynamics of such abnormalities in human cancer are not known. In this study, we examined centrosomes in Barrett's esophagus tumorigenesis, a well-characterized multistep pathway of progression, from the premalignant condition to the metastatic disease. This human cancer model allows the study of sequential steps of progression within the same patient and has representative cell lines from all stages of disease. Remarkably, centrosome amplification was detected as early as the premalignant condition and was significantly expanded in dysplasia. It was then present throughout malignant transformation both in adenocarcinoma and metastasis. The early expansion of centrosome amplification correlated with and was dependent on loss of function of the tumor suppressor p53 both through loss of wild-type expression and hotspot mutations. Our work shows that centrosome amplification in human tumorigenesis can occur before transformation, being repressed by p53. These findings suggest centrosome amplification in humans can contribute to tumor initiation and progression.Fundação para a Ciência e a Tecnologia–Harvard Medical School Program Portugal grant: (HMSP-CT/SAU-ICT/0075/2009); Liga Portuguesa Contra o Cancro; European Molecular Biology Organization Installation; Sociedade Portuguesa de Gastroenterologia.N/

Hadronization geometry from net-charge angular correlations on momentum subspace (η,ϕ\eta,\phi) in Au-Au collisions at sNN=130\sqrt{s_{NN}} = 130 GeV

We present the first measurements of charge-dependent correlations on angular difference variables $\eta_1 - \eta_2$ (pseudorapidity) and $\phi_1 - \phi_2$ (azimuth) for primary charged hadrons with transverse momentum $0.15 \leq p_t \leq 2$ GeV/$c$ and $|\eta| \leq 1.3$ from Au-Au collisions at $\sqrt{s_{NN}} = 130$ GeV. We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings along the beam direction to an at least two-dimensional hadronization geometry along the beam and azimuth directions of a hadron-opaque bulk medium.Comment: 8 pages, 4 figure

Sediment denitrification in the Mira estuary salt marshes

Sediment denitrification is a microbial process that converts dissolved inorganic nitrogen present in sediment porewaters to nitrogen gas, which is lost to the atmosphere. Sediment denitrification was determined as a flux of nitrogen gas from intact sediments incubated in gas-tight chambers. The present technique allows for the direct measurement od denitrification in undisturbed sediment cores under ambient conditions of oxygen, dissolved nutrients and temperature. Nitrogen gas flux was measured from Spartina maritima sediments taken from the Mira estuary salt marshes in southern Portugal, over six month period. DNF rates ranged from 0.42 to 20.86 mmoles N2.m2.day. Lowest rates were obtained during spring months when salt marshes presented a peak export of dissolved inorganic nitrogen to the Mira estuary. The lowest rate obtained in April seems to be related with the dissolved inorganic nitrogen export period that characterized the spring months in the Mira salt marshes. The highest rate was measured in July. During summer months, the flux of nitrate out of the sediments reached the higher values. This result suggests that nitrate produced by nitrification in the sediments during this time of the year appears to be an important substarte for DNF in the Mira salt marshes. In summer, there was also a substantial import of ammonium and nitrate into marsh. Although water column nitrate concentrations were not high, this fact does not eliminate the possibility that some nitrate from the water column enters the sediment and is denitrified

Avaliação das necessidades em água doce do estuário do Guadiana (Portugal) com recurso aos desembarques da pesca profissional.

The importance of the freshwater inflows to the estuarine and adjoining coastal waters fish communities are put in evidence and a relationship between the commercial fisheries landings and freshwater inflow is presented. For the period between 1988 and 2000, twenty-one different equations were obtained, relating fish catches landed at the Vila Real de Santo António harbor, and the freshwater flow of the River Guadiana. Spring and summer were the seasons of the year that showed a higher number of significant relationships between fresh water flow and commercial fisheries landings. Estimates indicated that a fish catch of 1220 t/ year would depend upon an annual freshwater inflow of 1280 hm3, distributed in the following way: 22.7 m3/ s during the wet season (December to March), 39.0 m3/ s during the spring (April and May), 18.3 m3/ s during the dry season (June to September) and 69.6 m3/ s during the autumn (October and November). A flushing flow of 280 hm3 (7.5 days/ year) should be added to the previous scenario, preferably during the spring