5,140 research outputs found
Output functions and fractal dimensions in dynamical systems
We present a novel method for the calculation of the fractal dimension of
boundaries in dynamical systems, which is in many cases many orders of
magnitude more efficient than the uncertainty method. We call it the Output
Function Evaluation (OFE) method. The OFE method is based on an efficient
scheme for computing output functions, such as the escape time, on a
one-dimensional portion of the phase space. We show analytically that the OFE
method is much more efficient than the uncertainty method for boundaries with
, where is the dimension of the intersection of the boundary with a
one-dimensional manifold. We apply the OFE method to a scattering system, and
compare it to the uncertainty method. We use the OFE method to study the
behavior of the fractal dimension as the system's dynamics undergoes a
topological transition.Comment: Uses REVTEX; to be published in Phys. Rev. Let
Residual effect of pesticides used in integrated appleproduction on Chrysoperlaexterna (Hagen) (Neuroptera: Chrysopidae) Larvae.
Side-effects of pesticides used to control tomato pests in Brazil on the egg parasitoid Trichogramma pretiosum riley (Hym.: Trichogrammatidae).
Differential mesenteric fat deposition in bovines fed on silage or concentrate is independent of glycerol membrane permeability
© The Animal Consortium 2011In the meat industry, the manipulation of fat deposition in cattle is of pivotal importance to improve production efficiency, carcass composition and ultimately meat quality. There is an increasing interest in the identification of key factors and molecular mechanisms responsible for the development of specific fat depots. This study aimed at elucidating the influence of breed and diet on adipose tissue membrane permeability and fluidity and their interplay on fat deposition in bovines. Two Portuguese autochthonous breeds, Alentejana and Barrosã, recognized as late- and early-maturing breeds, respectively, were chosen to examine the effects of breed and diet on fat deposition and on adipose membrane composition and permeability. Twenty-four male bovines from these breeds were fed on silage-based or concentrate-based diets for 11 months. Animals were slaughtered to determine their live slaughter and hot carcass weights, as well as weights of subcutaneous and visceral adipose depots. Mesenteric fat depots were excised and used to isolate adipocyte membrane vesicles where cholesterol content, fatty acid profile as well as permeability and fluidity were determined. Total accumulation of neither subcutaneous nor visceral fat was influenced by breed. In contrast, mesenteric and omental fat depots weights were higher in concentrate-fed bulls relative to silage-fed animals. Membrane fluidity and permeability to water and glycerol in mesenteric adipose tissue were found to be independent of breed and diet. Moreover, the deposition of cholesterol and unsaturated fatty acids, which may influence membrane properties, were unchanged among experimental groups. Adipose membrane lipids from the mesenteric fat depot of ruminants were rich in saturated fatty acids, and unaffected by polyunsaturated fatty acids dietary levels. Our results provide evidence against the involvement of cellular membrane permeability to glycerol on fat accumulation in mesenteric fat tissue of concentrate-fed bovines, which is consistent with the unchanged membrane lipid profile found among experimental groups.This study was supported by Fundação para a Ciência e a Tecnologia (FCT) through grant PTDC/CVT/2006/66114 and individual fellowships to Ana P. Martins (SFRH/BD/2009/65046), Ana S. H. Costa (SFRH/BD/2009/61068) and Susana V. Martins (SFRH/BPD/2009/63019). Paula A. Lopes is a researcher from the program ‘‘Ciência 2008’’ from FC
The Vampire and the FOOL
This paper presents new features recently implemented in the theorem prover
Vampire, namely support for first-order logic with a first class boolean sort
(FOOL) and polymorphic arrays. In addition to having a first class boolean
sort, FOOL also contains if-then-else and let-in expressions. We argue that
presented extensions facilitate reasoning-based program analysis, both by
increasing the expressivity of first-order reasoners and by gains in
efficiency
On multigraded generalizations of Kirillov-Reshetikhin modules
We study the category of Z^l-graded modules with finite-dimensional graded
pieces for certain Z+^l-graded Lie algebras. We also consider certain Serre
subcategories with finitely many isomorphism classes of simple objects. We
construct projective resolutions for the simple modules in these categories and
compute the Ext groups between simple modules. We show that the projective
covers of the simple modules in these Serre subcategories can be regarded as
multigraded generalizations of Kirillov-Reshetikhin modules and give a
recursive formula for computing their graded characters
Structural properties of crumpled cream layers
The cream layer is a complex heterogeneous material of biological origin
which forms spontaneously at the air-milk interface. Here, it is studied the
crumpling of a single cream layer packing under its own weight at room
temperature in three-dimensional space. The structure obtained in these
circumstances has low volume fraction and anomalous fractal dimensions. Direct
means and noninvasive NMR imaging technique are used to investigate the
internal and external structure of these systems.Comment: 9 pages, 4 figures, accepted in J. Phys. D: Appl. Phy
Efeitos colaterais de produtos fitossanitárioas utilizados no controle de Helicoverpa armigera sobre Trichogramma pretiosum (Hymenoptera: Trichogrammatidae).
No presente trabalho objetivou-se avaliar os efeitos dos produtos (g p.c./L de água): Bacillus thuringiensis (4); Baculovirus helicoverpa zea (0,008), clorfenapir (90), flupiradifurone (200) e metomil (107,5), sobre T. pretiosum. Ovos de Anagasta kuehniella (Lepidoptera: Pyralidae) contendo os parasitoides em suas fases imaturas (ovo-larva, pré-pupa e pupa) foram tratados com os produtos em torre de Potter.Resumo 10
Toxicidade de agrotóxicos utilizados em tomateiro ao parasitoide de ovos Trichogramma pretiosum (Hym.: Trichogrammatidae).
Objetivou-se com o presente trabalho avaliar a toxicidade dos inseticidas, dos fungicidas e dos herbicidas recomendados para o controle de insetos, doenças e plantas daninhas na cultura do tomateiro.Resumo expandido
Approaching the Coverability Problem Continuously
The coverability problem for Petri nets plays a central role in the
verification of concurrent shared-memory programs. However, its high
EXPSPACE-complete complexity poses a challenge when encountered in real-world
instances. In this paper, we develop a new approach to this problem which is
primarily based on applying forward coverability in continuous Petri nets as a
pruning criterion inside a backward coverability framework. A cornerstone of
our approach is the efficient encoding of a recently developed polynomial-time
algorithm for reachability in continuous Petri nets into SMT. We demonstrate
the effectiveness of our approach on standard benchmarks from the literature,
which shows that our approach decides significantly more instances than any
existing tool and is in addition often much faster, in particular on large
instances.Comment: 18 pages, 4 figure
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