127 research outputs found
The meteorologically driven circulation in mid-Chesapeake Bay
Utilizing 20 days of sea level elevation and current records in mid-Chesapeake Bay, the frequency structure of the meteorological forcing is investigated. For periods longer than 8 days the residual sea level inside the Bay is coupled to the coastal elevation forced by the onshore-offshore component of the wind, while at the 3–8 day scale the system was driven by the local longitudinal wind component. It is suggested, however, that the partition of energy between the longitudinal and lateral wind components may determine whether the Bay responds locally to the wind or to the coastal elevations. The 2–2.5 day sea level oscillations could not be identified with a seiche in the Bay; their source is not clear, but the atmospheric pressure is a possibility.The vertical structure of the residual currents through two cross-sections shows that the layers in the upper 8 m are directly driven by the wind, while in the deeper layers the flow is opposite the wind as a result of the surface slope associated with it. The lag in this counter flow increases from the bottom up and is explained in terms of the phase lag of the surface slope response to the wind and the depth dependence of the current response to the wind
Sedimentological characteristics of ice-wedge polygon terrain in Adventdalen (Svalbard): environmental and climatic implications for the late Holocene
Ice wedges are widespread periglacial features in
the landscape of Adventdalen, Svalbard. The networks of ice
wedges have created areas with well-developed polygonal
terrains in the lowest fluvial terraces in this valley. We have
examined the sedimentological characteristics of the northern
and southern banks of the Advent river for palaeoenvironmental
purposes. The base of two sedimentary sections
reported radiocarbon dates of 3.3 and 3.9 ka BP, respectively.
The northern site is constituted by three very different
lithostratigraphical units, which suggests that their formation
should be related to different environmental and climate
conditions. By contrast, the southern section shows a
rather homogeneous composition, with no significant variations
in grain size and organic matter content. In both cases
the uppermost sediments are constituted by a thick aeolian
deposit. According to our data, warmer climate conditions
may have prevailed during the mid Holocene until 3.3 ka BP
with widespread peat formation in the valley bottom. Subsequently,
a period with alternating soil formation and aeolian
sedimentation took place from 3 to 2.5 ka BP, probably due
to increasing climatic severity. During the last millennium a
long-term cooling trend has favoured aeolian deposition in
the lowest part of Adventdalen.info:eu-repo/semantics/publishedVersio
Determination of parathion in biological fluids by means of direct Solid Phase Microextraction.
A new and simple procedure for the determination
of parathion in human whole blood and urine using
direct immersion (DI) solid-phase microextraction (SPME)
and gas chromatography/mass spectrometry (GC/MS) is
presented. This technique was developed using only
100 ìL of sample, and ethion was used as internal standard
(IS). A 65-ìm Carbowax/divinylbenzene (CW/DVB)
SPME fibre was selected for sampling, and the main
parameters affecting the SPME process such as extraction
temperature, adsorption and desorption time, salt addition,
agitation and pH effect were optimized to enhance the
sensitivity of the method. This optimization was also
performed to allow the qualitative determination of parathion’s
main metabolite, paraoxon, in blood. The limits
of detection and quantitation for parathion were 3 and
10 ng/mL for urine and 25 and 50 ng/mL for blood,
respectively. For paraoxon, the limit of detection was
50 ng/mL in blood. The method showed linearity between
the LOQ and 50 ìg/mL for both matrices, with correlation
coefficients ranging from 0.9954 to 0.9999. Precision and
accuracy were in conformity with the criteria normally
accepted in bioanalytical method validation. The mean
absolute recoveries were 35.1% for urine and 6.7% for
blood. Other parameters such as dilution of sample and
stability were also validated. Its simplicity and the fact that
only 100 ìL of sample is required to accomplish the analysis make this method useful in forensic toxicology laboratories
to determine this compound in intoxications, and it can be
considered an alternative to other methods normally used for
the determination of this compound in biological media
Governance with complex structures: evidence from Western European countries
This paper investigates if the existence of complex structures plays an important role in corporate governance. It uses GMM estimation on a panel of Western European firms. We find that the presence of a second and third large shareholder has a significant positive effect on firm value. This study underlines the importance of the number of blockholders as a determinant of firm value, when taken as a moderator of the contestability effect. It shows that the legal context and company-specific characteristics play a crucial moderating role for contestability. In contrast to previous research, we find that contestability plays a less relevant role in family firms. We also find that this last result does not vary significantly with the identity of the remaining elements of the coalition. Also, our study suggests that contestability is less important in companies led by majority shareholders
Identification of cell-surface mannans in a virulent Helicobacter pylori strain
With the intent of contributing to a carbohydrate-based vaccine against the gastroduodenal pathogen, Helicobacter pylori, we report here the structure of cell-surface mannans obtained from a virulent strain. Unlike other wild-type strains, this strain was found to express in good quantities this polysaccharide in vitro. Structural analysis revealed a branched mannan formed by a backbone of α-(1→6)-linked mannopyranosyl residues with approximately 80% branching at the O-2 position. The branches were composed of O-2-linked Man residues in both α- and β-configurations: (image)
In addition, this strain also expressed cell-surface emblematic H. pylori lipopolysaccharides (LPS) containing partially fucosylated polyLacNAc O-chains. Affinity assays with polymyxin-B and concanavalin A revealed no association between the mannan and the LPS. The described mannans may be implicated in the mediation of host–microbial interactions and immunological modulation.This work was supported by Fundacao para a Ciencia e Tecnologia (FCT) through project Pylori E&LPS POCI/QUI/56393/2004, PhD grant SFRH/BD/19929/2004, by the Natural Sciences and Engineering Research Council of Canada (NSERC), and by the European Network of Research Infrastructures within the 6th Framework Programme of the EC (Contract # RII3-026145, EU-NMR). The authors further thank Dr. Adrien Favier (RALF-NMR facility, Grenoble - France) for conducting NMR experiments
Opinião dos encarregados de educação relativamente à dinâmica das aulas de natação para bebés no distrito de Setúbal
info:eu-repo/semantics/publishedVersio
Validation of a fluorescence in situ hybridization method using peptide nucleic acid probes for detection of Helicobacter pylori clarithromycin resistance in gastric biopsy specimens
Here, we evaluated a previously established peptide nucleic acid-fluorescence in situ hybridization (PNA-FISH) method as a new diagnostic test for Helicobacter pylori clarithromycin resistance detection in paraffin-embedded gastric biopsy specimens. Both a retrospective study and a prospective cohort study were conducted to evaluate the specificity and sensitivity of a PNA-FISH method to determine H. pylori clarithromycin resistance. In the retrospective study (n=30 patients), full agreement between PNA-FISH and PCR-sequencing was observed. Compared to the reference method (culture followed by Etest), the specificity and sensitivity of PNA-FISH were 90.9% (95% confidence interval [CI], 57.1% to 99.5%) and 84.2% (95% CI, 59.5% to 95.8%), respectively. In the prospective cohort (n=93 patients), 21 cases were positive by culture. For the patients harboring clarithromycin- resistant H. pylori, the method showed sensitivity of 80.0% (95% CI, 29.9% to 98.9%) and specificity of 93.8% (95% CI, 67.7% to 99.7%). These values likely represent underestimations, as some of the discrepant results corresponded to patients infected by more than one strain. PNA-FISH appears to be a simple, quick, and accurate method for detecting H. pylori clarithromycin resistance in paraffin-embedded biopsy specimens. It is also the only one of the methods assessed here that allows direct and specific visualization of this microorganism within the biopsy specimens, a characteristic that allowed the observation that cells of different H. pylori strains can subsist in very close proximity in the stomach. Copyright © 2013, American Society for Microbiology. All Rights Reserved.This work was supported by the Portuguese Institute Fundacao para a Ciencia e a Tecnologia (Ph.D. grant SFRH/BD/38124/2007 and project PIC/IC/82815/2007)
Descrição da biodiversidade terrestre e marinha dos Açores
1. Os Açores sĂŁo um arquipĂ©lago isolado de nove ilhas oceânicas, pertence Ă regiĂŁo biogeográfica da MacaronĂ©sia e está entre as regiões mais ricas em fungos, plantas e animais da Europa. Este capĂtulo destaca o que sabemos sobre os fungos, a fauna e a flora dos habitats terrestres, dulçaquĂcolas e marinhos dos Açores. 2. Neste capĂtulo, sĂŁo apresentadas as estimativas do nĂşmero total de espĂ©cies e subespĂ©cies conhecidas actualmente nos Açores. Todos os grupos taxonĂłmicos terrestres mais importantes foram analisados: fungos, lĂquenes, diatomáceas dulçaquĂcolas, briĂłfitos (musgos, hepáticas e antocerotas), plantas vasculares (licĂłfitas, fetos, gimnospĂ©rmicas e angiospĂ©rmicas), platelmintes (vermes), nemátodos, anelĂdeos (minhocas), moluscos terrestres (lesmas e caracĂłis), artrĂłpodes (insectos, aracnĂdeos, milĂpedes, etc.) e vertebrados (peixes de água doce, anfĂbios, rĂ©pteis, aves e mamĂferos). A presente obra inclui tambĂ©m espĂ©cies do ambiente marinho, como as algas (macroalgas), a maioria dos filos de invertebrados do litoral e os vertebrados marinhos (rĂ©pteis, peixes e mamĂferos). As listas de espĂ©cies e subespĂ©cies (CapĂtulos 2-15) sĂŁo baseadas nos taxa identificados numa grande variedade de publicações, tendo essa informação sido compilada por um vasto grupo de especialistas. 3. Actualmente, o nĂşmero total de taxa (espĂ©cies e subespĂ©cies) terrestres nos Açores está estimado em cerca de 6164 (cerca de 6112 espĂ©cies). A inclusĂŁo de uma listagem exaustiva das espĂ©cies de aves nĂŁo-nidificantes e de uma listagem preliminar de espĂ©cies de aves potencialmente nidificantes acrescenta 325 espĂ©cies e subespĂ©cies ao total das espĂ©cies açorianas. 4. O nĂşmero total de espĂ©cies e subespĂ©cies endĂ©micas terrestres dos Açores Ă© de cerca de 452 (411 espĂ©cies). Os animais sĂŁo os mais diversos em endemismos, com 331 taxa (Arthropoda = 266; Mollusca = 49; Vertebrata = 14; Nematoda = 2), compreendendo cerca de 73% dos endemismos terrestres dos Açores. A percentagem de endemismo nos Mollusca (44%) Ă© notável. As plantas vasculares contam com 73 endemismos, os Fungi (incluindo os lĂquenes) tĂŞm 34 e, tanto as diatomáceas dulçaquĂcolas como os briĂłfitos, incluem sete espĂ©cies endĂ©micas. 5. Quando comparada com os arquipĂ©lagos vizinhos da MacaronĂ©sia (Madeira e Canárias), a fauna e flora terrestres dos Açores Ă© caracterizada por uma menor taxa de endemismo, de apenas 7%, contrastando com os cerca de 20% para a Madeira e de 30% para as Canárias. 6. No que diz respeito aos organismos marinhos, sĂŁo listados 1883 taxa pertencentes a 16 filos. O nĂşmero total de espĂ©cies e subespĂ©cies marinhas endĂ©micas dos Açores Ă© de cerca de 39, a maior parte delas moluscos (29 espĂ©cies). 7. O nĂşmero total de taxa terrestres e marinhos (espĂ©cies e subespĂ©cies) nos Açores, está estimado em cerca de 8047. Os organismos marinhos agora listados, perfazem cerca de 23% da biodiversidade dos Açores. 8. O nĂşmero total de taxa terrestres e marinhos (espĂ©cies e subespĂ©cies) endĂ©micos dos Açores está estimado em cerca de 491.ABSTRACT: 1. The Azores is a remote oceanic archipelago of nine islands which belongs to the Macaronesia biogeographical region and is among the richest regions concerning fungi, plant and animal diversity in Europe. This chapter highlights what we know about the Azorean terrestrial, freshwater and marine Fungi, Flora and Fauna. 2. In this chapter we summarize the current estimates of the total number of species and subspecies presently known to occur in the Azores. The most important terrestrial taxonomic groups were studied: Fungi, Lichens, Bacillariophyta (freshwater diatoms), Bryophyta sensu lato (mosses, liverworts and hornworts), vascular plants – Tracheobionta, including Lycopodiophyta (quillworts), Pteridophyta (ferns), Pinophyta (gymnosperms) and Magnoliophyta (angiosperms), Platyhelminthes (flatworms), Nematoda (roundworms), Annelida (earthworms), Terrestrial Mollusca (slugs and snails), Arthropoda (millipedes, centipedes, mites, spiders, insects, etc.) and Vertebrata (freshwater fishes, amphibians, reptiles, birds and mammals). In addition, we expand this list to the marine realm, including Algae (macroalgae), coastal invertebrates (most Phyla) and marine vertebrates (fishes, reptiles and mammals). The list of species and subspecies (Chapters 2 to 15) is based on the taxa recognized in primary published literature sources, compiled by a vast group of experts. 3. Currently the total number of terrestrial taxa (species and subspecies) in the Azores is estimated of about 6164 (about 6112 species). The inclusion of an exhaustive listing of non breeding species and a preliminary list of potentially breeding species adds 325 species and subspecies of birds to the Azorean list of species. 4. The total number of terrestrial endemic species and/or subspecies from the Azores is about 452 (411 species). Animals are the most represented in this respect, with 331 taxa (Arthropoda = 266; Mollusca = 49; Vertebrata = 14; Nematoda = 2), that is, about 73% of the Azorean terrestrial endemics. The percentage of endemism within Mollusca (44%) is remarkable. Vascular plants have 73 endemic taxa, while Fungi (including Lichens) have 34, freshwater diatoms and bryophytes have seven endemic species each. 5. Compared to the other nearest Macaronesian archipelagos (Madeira and Canaries), the Azorean terrestrial fauna and flora is characterized by a lower percentage of endemism (only 7%, which contrasts with nearly 20% for Madeira and 30% for the Canary islands). 6. Concerning the marine organisms, we listed about 1883 taxa belonging to 16 Phyla. The total number of marine endemic species and/or subspecies from the Azores is about 39, most of them being molluscs (29 species). 7. Currently, the total number of terrestrial and marine taxa (species and subspecies) in the Azores is estimated in about 8047. The marine organisms currently listed make up about 23% of the Azorean biodiversity. 8. Currently, the total number of terrestrial and marine endemic taxa (species and subspecies) in the Azores is estimated of about 491
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