1,254 research outputs found
Description and molecular phylogeny of a new and one known needle nematode of the genus Paralongidorus (Nematoda: Longidoridae) from grapevine in Portugal
A new and a known longidorid nematode, Paralongidorus lusitanicus n. sp. and Paralongidorus plesioepimikis, are described and illustrated from populations extracted from soil associated with grapevine (Vitis vinifera L.) from Escaroupim and Pó (central-Western Portugal), respectively. The new needle nematode P. lusitanicus n. sp. is characterised by a very large body size (8072–12,022 μm), an expanded and rounded lip region, ca 30 μm wide, with a clear constriction followed by a depression posterior to the amphidial aperture, amphidial fovea very large (11.0–19.0 μm), stirrup-shaped, with conspicuous slit-like aperture as shown in scanning electron microscopy studies, a very long and flexible odontostyle (180.0–223.0 μm), guiding ring located at 28.0–41.5 μm from anterior end, vulva anterior to the mid-body (34–41%), a dorsally convex-conoid tail with rounded terminus (29–42 μm long), bearing two or three pairs of caudal pores and males common (ratio 1:1.6 females) with spicules ca 80 μm long. Morphological and morphometric traits for P. plesioepimikis fit well with the original description, and is reported for the first time in Portugal. Integrative diagnosis of both species was completed with molecular data obtained using D2-D3 expansion segments of 28S rDNA, ITS1-rDNA and partial 18S–rDNA. The phylogenetic relationships of these species with other Paralongidorus spp. using these three molecular markers indicated that P. lusitanicus n. sp. clustered together with other Paralongidorus spp. forming a sister clade with P. plesioepimikis, both of them sharing a large body, long odontostyle, an anteriorly located vulva and an expanded and rounded lip region with a clear constriction followed by a depression posterior to the amphidial aperture
Residual stress measurement in PVD optical coatings by microtopography
Residual stress in optical plasma vapor deposited coatings must be carefully measured. The topographic inspection of the coatings’ surface at microlevel allows the assessment of its residual stress. In the present work we will report on the optical non-destructive and non-invasive microtopographic inspection of WO3 PVD thin films for residual stress evaluation. The MICROTOP.06.MFC system, an active optical triangulation sensor developed at the Universidade do Minho, was employed. It allows depth resolutions down to 2 nm and lateral resolutions down to 1 μm. The three dimensional coordinate set obtained on the inspection allow the calculation of the stress distribution over the film
Conceptualizing Aeolian Sediment Transport in a Cellular Automata Model to Simulate the Bio-Geomorphological Evolution of Beach–Dune Systems
Symbolic Computation of Variational Symmetries in Optimal Control
We use a computer algebra system to compute, in an efficient way, optimal
control variational symmetries up to a gauge term. The symmetries are then used
to obtain families of Noether's first integrals, possibly in the presence of
nonconservative external forces. As an application, we obtain eight independent
first integrals for the sub-Riemannian nilpotent problem (2,3,5,8).Comment: Presented at the 4th Junior European Meeting on "Control and
Optimization", Bialystok Technical University, Bialystok, Poland, 11-14
September 2005. Accepted (24-Feb-2006) to Control & Cybernetic
Structure determination of Split-soret Cytochrome from a Desulfovibrio species isolated from a human abdominal abcess
The determined structure of the split-soret cytochrome (SSC) isolated from Desulfovibrio desulfuricans ATCC 27774 (D.d.) revealed a new Heme arrangement, which suggests that this protein constitutes a new cytochrome class.. SSC is a 52.6kDa homodimer containing four hemes at one end of the molecule. In each monomer the two hemes have their edges overlapped within van der Waals contacts. The polypeptide chain of each monomer supplies the sixth ligand to the heme-iron of the other monomer. A similar protein was recently purified from a homologous Desulfovibrio clinical strain isolated from an abdominal wall abscess in human patient2. Crystals of this SSC were grown using vapour diffusion method in the presence of agarose gel. Diffraction data were collected using X-ray synchrotron radiation at the ESRF, beamline, ID 14-1. The structure will be solved by molecular replacement using the structure of the D.d. as a starting model
Exergy efficiency optimization for gas turbine based cogeneration systems
Energy degradation
can be calculated
by
the
quantification
of
entropy and loss
of work
and
is a common approach in
power plant performance analysis. Information about the
location, amount and
sourc
es of system deficiencies are
determined by
the
exergy analysis, which
quantifies the
exergy
destruction.
Micro
-
gas turbines are
prime movers
that are
ideally suited for cogeneration applications due to their
flexibility in providing stable and reliable power. This paper
presents
an
exergy analysis
by means of a
numerical
simulation
of a
regenerative
micro
-
gas turbine
for cogeneration
applications
. The main objective is
to study
the best
configuration of each system component
,
considering the minimization of the
system irreversibilities
. Each component of
the system was evaluated
considering the quantitative exergy
balance
.
Subsequently the optimization
procedure
was applied
to the mathematical model that
describes the
full
system.
The rate of irreversibility, efficiency and flaws are
highlighted for each system component and for
the
whole
system.
The effect
of turbine inlet temperature
change
on plant
exergy destruction
was also evaluated
. The results disclose that
considerable exergy destruction occurs in the combustion
chamber. Also, it
was revealed that the exergy
efficiency is
expressively
dependent on the
changes
of
the turbine inlet
temperature
and increases with
the
latter
.The authors would like to express their acknowledgments for the support given by the Portuguese F01mdation for Science and Technology (FCT) through the PhD grant SFRH/BD/62287/2009. This work was financed by National Funds-Portuguese Foundation for Science and Technology, under Strategic Project and PEst-OE/EME/UI0252/2011 and also the PEst-C/EME/UI4077/2011
Electrochemical Performances of Li+ Intercalation and Deintercalation Processes for Electrochromism of MoO3-Doped V2o5 Films Prepared By The Sol-Gel Method
MoO3-doped V2O5 thin films electrode exhibit much enhanced
electrochemical performances than the pure V2O5 counterpart. 1M nonaqueous solution of
LiClO4 in propylene carbonate (PC) was the electrolyte solution about cyclic voltammetry
(CV) of V2O5/MoO3/ITO glass electrodes at room temperature. With the increasing
proportion of MoO3 doped in V2O5, all the redox peak currents of the five samples increased,
suggesting that their electrochemical activity increased with the initial CV cycles.
Disappearing of some phase transition peaks also show that the MoO3-doped V2O5 film
makes cyclic stability declining. Compared with the switching speed of films, the coloring
and the bleaching times of the MoO3-doped V2O5 thin films are shorter
Agency Costs, Firm Value, and Corporate Investment
Often firms lack the necessary internal resources to pursue all profitable investment opportunities at their disposal. One of the most important roles of financial markets is to allocate resources from different economic agents to the firms that will better employ them, thereby enabling productive investment to take place. However, there are informational and incentive-related problems in financial markets that result in agency costs. These costs can hinder the efficient allocation of capital across the economy and, as a result, can impact economic growth. This thesis examines the mechanisms that investors and managers use to reduce the agency costs of outside financing and the impact of such costs on firms’ investment decisions and value. The first chapter shows that the voluntary disclosure of information can help overcoming the informational asymmetry between managers and investors. The second chapter provides evidence that institutional ownership of firms can improve firm decisions and increase firm value when coupled with the appropriate incentives. In particular, we show that stock illiquidity is a key incentive in this setting. The last chapter examines the impact of accessing the public debt market on corporate investment. The findings support the hypothesis that firms adjust their investment decisions to offset an increase in agency costs, which in turn enables them to access outside financing on more favorable terms
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