744 research outputs found
Correlations in Networks associated to Preferential Growth
Combinations of random and preferential growth for both on-growing and
stationary networks are studied and a hierarchical topology is observed. Thus
for real world scale-free networks which do not exhibit hierarchical features
preferential growth is probably not the main ingredient in the growth process.
An example of such real world networks includes the protein-protein interaction
network in yeast, which exhibits pronounced anti-hierarchical features.Comment: 4 pages, 4 figure
Secuestro de C en plantaciones de Eucalyptus spp establecidas en terrenos agrícolas en el norte de España
Una de las estrategias que se ha planteado para fijar
gases con efecto invernadero (CO2, CH4 y N2O) es el
aumento de la superficie forestal. España es uno de
los países que más han contribuido a incrementar la
superficie forestal en Europa, lo que se debe en
buena parte al establecimiento de parcelas en tierras
agrarias en situación de marginalidad. Durante el
período de 11 años, transcurridos entre el segundo y
el tercer inventarios forestales (1987 y 1998), el
almacenamiento de C en biomasa arbórea en el norte
de España ha aumentado en un 50 %. En este trabajo
se realiza una primera estimación de las ganancias
de C en biomasa y suelo en plantaciones de
eucalipto establecidas en terrenos agrícolas.
Para ello se seleccionaron un total de 25 pares de
parcelas. Se trata de parcelas agrarias en las cuales
parte de la superficie se transformó a plantación de
Eucalyptus sp. En estas parcelas se determinó la
acumulación de C en biomasa arbórea, mantillo y
suelo en tres profundidades 0-5, 5-15 y 15-30 cm.
Dado las mejores condiciones de fertilidad y mayor
profundidad, que promueven el crecimiento arbóreo,
la tasa de acumulación de C en biomasa es
considerablemente superior a las plantaciones
establecidas en suelos forestales. Los datos de este
trabajo muestran acumulaciones superiores a 17 Mg
ha-1 año-1. La acumulación de C en el mantillo
también es superior a 1 Mg ha-1 año-1. En cuanto al
suelo mineral, las pérdidas de C se reducen con los
años desde el cambio de uso, fundamentalmente a
partir de los 15 años del establecimiento y en
plantaciones sobre esquistos y pizarras. Hasta ese
momento se produjeron ligeras pérdidas.____________________________________One of the strategies proposed for fixing gases that
contribute to the greenhouse effect (CO2, CH4 and
N2O) is to increase the extension of land covered by
forest. Spain is one of the countries that has
contributed most to the increase in the forest area in
Europe, largely due to the establishment of forest
plots on marginal agricultural land. During the 11-
year period between the second and third forest
inventories (1987 and 1998), there has been a 50%
increase in the storage of C in tree biomass in
northern Spain. In the present study, a first estimate
was made of the increase in C in biomass and soil in
eucalyptus plantations established on agricultural
land.
A total of 25 pairs of plots were selected for the
study. The plots are on agricultural land, part of
which has been transformed by plantation of
Eucalyptus sp. The amount of C accumulated in the
tree biomass, humus and three different depths of
soil (0-5, 5-15 and 15-30 cm) was determined.
Given the more fertile conditions and the greater
depth of the soil, which favour tree growth, the rate
of accumulation of C in the biomass was
considerably higher than in plantations established
on forest soils. The data obtained in the present
study revealed accumulations of C of more than 17
Mg ha-1 year-1. Accumulation of C in the humus was
also higher than 1 Mg ha-1 year-1. The losses of C in
the mineral soil decreased since the change in land
use, generally from 15 years after establishment
onwards, and in plantations on schists and slates.
Slight losses of C were observed up until this time
Serum and cerebrospinal fluid biomarkers in neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein associated disease
The term neuromyelitis optica spectrum disorder (NMOSD) describes a group of clinical-MRI syndromes characterized by longitudinally extensive transverse myelitis, optic neuritis, brainstem dysfunction and/or, less commonly, encephalopathy. About 80% of patients harbor antibodies directed against the water channel aquaporin-4 (AQP4-IgG), expressed on astrocytes, which was found to be both a biomarker and a pathogenic cause of NMOSD. More recently, antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG), have been found to be a biomarker of a different entity, termed MOG antibody-associated disease (MOGAD), which has overlapping, but different pathogenesis, clinical features, treatment response, and prognosis when compared to AQP4-IgG-positive NMOSD. Despite important refinements in the accuracy of AQP4-IgG and MOG-IgG testing assays, a small proportion of patients with NMOSD still remain negative for both antibodies and are called "seronegative" NMOSD. Whilst major advances have been made in the diagnosis and treatment of these conditions, biomarkers that could help predict the risk of relapses, disease activity, and prognosis are still lacking. In this context, a number of serum and/or cerebrospinal fluid biomarkers are emerging as potentially useful in clinical practice for diagnostic and treatment purposes. These include antibody titers, cytokine profiles, complement factors, and markers of neuronal (e.g., neurofilament light chain) or astroglial (e.g., glial fibrillary acidic protein) damage. The aim of this review is to summarize current evidence regarding the role of emerging diagnostic and prognostic biomarkers in patients with NMOSD and MOGAD
Calculation of mackerel adult parameters for the application of the DEPM in the western spawning area
The ICES Working Group on Mackerel and Horse Mackerel Egg Surveys (WGMEGS) coordinates the mackerel and horse mackerel egg survey in the Northeast Atlantic (NEA) and the mackerel egg survey in the North Sea. The working group plans and reports on these surveys, with recent attention focused on the execution of the surveys given the increasing demands related to covering the expanding survey area as well as balanced fecundity sampling. WGMEGS also addresses data quality assurance in macke-rel fecundity and total annual egg production estimation.Currently, there are 3 surveys in place which are carried out triennially and deliver standing stock bio-mass (SSB) indices: (1) the survey for the western and southern stock components of the NEA mackerel stock, as well as for the western horse mackerel stock, (2) the survey for the NEA mackerel North Sea stock component, and (3) the survey for the southern horse mackerel stock.For the North Sea component, the egg survey in 2017 revealed an estimated egg production of 201*1012, resulting in an SSB of 287*103 tons. This is a strong increase of more than 100*103 tons com-pared to 2015 (SSB = 170*103 tons). While peak spawning in the North Sea was covered, the coverage of the complete spawning season and area was insufficient to produce a reliable estimate of survey in-dices.In 2019, the application of an alternate transect survey design made it possible to survey the persis-tently expanding mackerel spawning area and season. Northern and northwestern spawning bounda-ries for mackerel during survey periods 5 (weeks 19 – 22) and 6 (weeks 23 – 26) were not fully deline-ated. Peak spawning was observed in period 4 (weeks 16 – 18). Subsequent analyses of survey results in conjunction with results from exploratory surveys in the inter-survey-years showed that the mackerel core spawning area was covered and a reliable estimate of mackerel annual egg production was deliv-ered. The estimate of total mackerel egg production was 1.64*1015, which is a decrease of 7.6% com-pared to that of 2016 (rev. 1.77*1015).Realized fecundity was estimated at 1147 per g female, revealing the SSB for the NEA mackerel stock in 2019 at 3.09 million tons indicating at 12 % decrease since the 2016 survey (SSB = 3.52 million tons). At only 1.78*1014 , total annual egg production (TAEP) in western horse mackerel was found to be lowest production reported in the time series since 1992. The spawning maximum was detected in the last pe-riod 7 (weeks 27 – 29). It can, thus, not be concluded that peak spawning and the entire temporal ex-tent of horse mackerel spawning had been sufficiently covered.To further improve the quality of the index time series, WGMEGS will continue to dedicate much of its work to survey design and quality assurance in mackerel egg production and fecundity estimation
Silicon-hydroxyapatite bioactive coatings (Si-HA) from diatomaceous earth and silica. Study of adhesion and proliferation of osteoblast-like cells
The aim of this study consisted on investigating
the influence of silicon substituted hydroxyapatite (Si–HA)
coatings over the human osteoblast-like cell line (SaOS-2)
behaviour. Diatomaceous earth and silica, together with
commercial hydroxyapatite were respectively the silicon
and HA sources used to produce the Si–HA coatings. HA
coatings with 0 wt% of silicon were used as control of the
experiment. Pulsed laser deposition (PLD) was the selected
technique to deposit the coatings. The Si–HA thin films
were characterized by Fourier Transformed Infrared
Spectroscopy (FTIR) demonstrating the efficient transfer of
Si to the HA structure. The in vitro cell culture was
established to assess the cell attachment, proliferation and
osteoblastic activity respectively by, Scanning Electron
Microscopy (SEM), DNA and alkaline phosphatase (ALP)
quantification. The SEM analysis demonstrated a similar
adhesion behaviour of the cells on the tested materials and
the maintenance of the typical osteoblastic morphology
along the time of culture. The Si–HA coatings did not
evidence any type of cytotoxic behaviour when compared
with HA coatings. Moreover, both the proliferation rate
and osteoblastic activity results showed a slightly better
performance on the Si–HA coatings from diatoms than on
the Si–HA from silica.This work was supported by the UE-Interreg IIIA (SP1.P151/03) Proteus project and Xunta de Galicia ( Projects: 2006/12 and PGIDITO5PXIC30301PN)
A quantitative analysis of measures of quality in science
Condensing the work of any academic scientist into a one-dimensional measure
of scientific quality is a difficult problem. Here, we employ Bayesian
statistics to analyze several different measures of quality. Specifically, we
determine each measure's ability to discriminate between scientific authors.
Using scaling arguments, we demonstrate that the best of these measures require
approximately 50 papers to draw conclusions regarding long term scientific
performance with usefully small statistical uncertainties. Further, the
approach described here permits the value-free (i.e., statistical) comparison
of scientists working in distinct areas of science.Comment: 11 pages, 8 figures, 4 table
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