1,884 research outputs found
Variation in Patterns of Metal Accumulation in Thallus Parts of Lessonia trabeculata (Laminariales; Phaeophyceae): Implications for Biomonitoring
Seaweeds are well known to concentrate metals from seawater and have been
employed as monitors of metal pollution in coastal waters and estuaries.
However, research showing that various intrinsic and extrinsic factors can
influence metal accumulation, raises doubts about the basis for using seaweeds
in biomonitoring programmes. The thallus of brown seaweeds of the order
Laminariales (kelps) is morphologically complex but there is limited
information about the variation in metal accumulation between the different
parts, which might result in erroneous conclusions being drawn if not accounted
for in the biomonitoring protocol. To assess patterns of individual metals in
the differentiated parts of the thallus (blade, stipe, holdfast),
concentrations of a wide range of essential and non-essential metals (Fe, Cr,
Cu, Zn, Mn, Pb, Cd, Ni and Al) were measured in the kelp Lessonia trabeculata.
Seaweeds were collected from three sampling stations located at 5, 30 and 60 m
from an illegal sewage outfall close to Ventanas, Chile and from a pristine
location at Faro Curaumilla. For the majority of metals the highest
concentrations in bottom sediment and seaweed samples were found at the site
closest to the outfall, with concentrations decreasing with distance from the
outfall and at control stations; the exception was Cd, concentrations of which
were higher at control stations. The patterns of metal concentrations in
different thallus parts were metal specific and independent of sampling
station. These results and the available literature suggest that biomonitoring
of metals using seaweeds must take account of differences in the accumulation
of metals in thallus parts of complex seaweedsComment: Research articl
Propiedades Psicométricas del Inventario Psicológico de Ejecución Deportiva (IPED) en deportistas peruanos de Alto Rendimiento
To measure athlete's success and his sports performance, it is required to quantify the maximum performance developed during seasons of trainings and championships; using a valid, reliable, and adapted to peruvian context instrument. However, caution is urged when considering there is no psychometric evidence to support the use of any scale related to peruvian high performance athletes' sample. The current study was designed to evaluate the psychometric properties of the Sports Performance Psychological Inventory (IPED) in the mentioned sample. Method: Participated 255 peruvian athletes with ages between 14 and 38 years (N:23; SD: 4.29); who actively represents the country and in sports modalities affiliated with the Peruvian Sports Institute (IPD). For the collection of information, a sociodemographic record, Sports Performance Psychological Inventory (IPED) and the Mental Toughness Questionnaire (MTQ) were used. Results: IPED model demonstrated, that the seven-dimensional model had an acceptable fit (SBx2 = 2243.096 / df = 798; CFI=. 955; SRMR=. 095; RMSEA=. 084 [IC90%:. 080 -. 069] and reliability analyses revealed high internal consistency (ω =. 841 > ω =. 754). In addition, scores correlated positively between IPP and MTQ dimensions (AC=. 678; CAN=. 557; CAT=. 457; CVI=. 328; NM=. 425; CAP=. 641; CAC=. 662) and Control (AC=. 558; CAN=. 733; CAT=. 682; CVI=. 171; NM=. 272; CAP=. 432; CAC=. 563) Conclusion: The IPED provides adequate evidence of validity and reliability to measure sports performanc
Crocodylian diversity peak and extinction in the late Cenozoic of the northern Neotropics
Northern South America and South East Asia are today’s hotspots of crocodylian diversity with up to six (mainly alligatorid) and four (mainly crocodylid) living species respectively, of which usually no more than two or three occur sympatrically. In contrast, during the late Miocene, 14 species existed in South America. Here we show a diversity peak in sympatric occurrence of at least seven species, based on detailed stratigraphic sequence sampling and correlation, involving four geological formations from the middle Miocene to the Pliocene, and on the discovery of two new species and a new occurrence. This degree of crocodylian sympatry is unique in the world and shows that at least several members of Alligatoroidea and Gavialoidea coexisted. By the Pliocene, all these species became extinct, and their extinction was probably related to hydrographic changes linked to the Andean uplift. The extant fauna is first recorded with the oldest Crocodylus species from South America.Facultad de Ciencias Naturales y Muse
Transfer/Breakup Modes in the 6He+209Bi Reaction Near and Below the Coulomb Barrier
Reaction products from the interaction of 6He with 209Bi have been measured
at energies near the Coulomb barrier. A 4He group of remarkable intensity,
which dominates the total reaction cross section, has been observed. The
angular distribution of the group suggests that it results primarily from a
direct nuclear process. It is likely that this transfer/breakup channel is the
doorway state that accounts for the previously observed large sub-barrier
fusion enhancement in this system.Comment: 4 pages; 3 figure
Dirichlet Branes on Orientifolds
We consider the classification of BPS and non-BPS D-branes in orientifold
models. In particular we construct all stable BPS and non-BPS D-branes in the
Gimon-Polchinski (GP) and Dabholkar-Park-Blum-Zaffaroni (DPBZ) orientifolds and
determine their stability regions in moduli space as well as decay products. We
find several kinds of integrally and torsion charged non-BPS D-branes. Certain
of these are found to have projective representations of the orientifold
GSO group on the Chan-Paton factors. It is found that the GP
orientifold is not described by equivariant orthogonal K-theory as may have
been at first expected. Instead a twisted version of this K-theory is expected
to be relevant.Comment: 33 pages, LaTeX, 5 figures. v2 typos corrected, references included,
(4,s)-branes re-examine
Resistance to autosomal dominant Alzheimer's disease in an APOE3 Christchurch homozygote: a case report.
We identified a PSEN1 (presenilin 1) mutation carrier from the world's largest autosomal dominant Alzheimer's disease kindred, who did not develop mild cognitive impairment until her seventies, three decades after the expected age of clinical onset. The individual had two copies of the APOE3 Christchurch (R136S) mutation, unusually high brain amyloid levels and limited tau and neurodegenerative measurements. Our findings have implications for the role of APOE in the pathogenesis, treatment and prevention of Alzheimer's disease
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