Polinização por abelhas em Aechmea caudata lindm., uma bromélia com características ornitófilas, na ilha de Santa Catarina, Sul do Brasil

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-graduação em Biologia Vegetal, Florianópolis, 2009A maioria das espécies de Bromeliaceae é polinizada por beija-flores, mas borboletas e, principalmente, abelhas estão entre os visitantes florais mais freqüentes em algumas bromélias ornitófilas de corola curta. A importância dos visitantes florais para a polinização de Aechmea caudata foi determinada através da freqüência e a eficiência de polinização desses visitantes. Foi determinado também o sistema reprodutivo e a taxa natural de frutificação e produção de sementes, além do registro da fenologia de A. caudata. Os estudos foram desenvolvidos em uma área secundária de Mata Atlântica na Ilha de Santa Catarina. Ao longo de um transecto (1 ha), foram realizadas 62 horas de observações focais entre março de 2008 e março de 2009. Aechmea caudata produziu néctar ao longo de toda a antese (das 05:00 às 20:00 h) e é uma espécie auto-incompatível, portanto, dependente de polinizadores para a formação de sementes. No total, 16 espécies de quatro ordens animais foram registradas nas flores obtendo o néctar e pólen em visitas legítimas. As abelhas (nove espécies) foram as mais diversas e freqüentes, com 91% do total de 647 visitas, enquanto as cinco espécies de borboletas representaram apenas 6,7% das visitas, além de uma única visita de Coereba flaveola (cambacica). Apesar de apresentar características ornitófilas, A. caudata foi visitada pelo beija-flor Thalurania glaucopis apenas ocasionalmente (16 visitas). Essa baixa taxa de visitação pode estar associada a uma pequena população de T. glaucopis na área, cuja demanda energética é suportada por outras fontes alimentares sem a necessidade de competir com as abelhas pelo néctar de A. caudata. Contrariamente ao hipotetizado, os testes de eficiência de polinização demonstraram que as visitas do beija-flor não resultaram em polinização cruzada; apenas as visitas de Bombus morio promoveram a formação de sementes. Estes resultados evidenciam a importância de co-polinizadores para espécies de plantas cujos polinizadores primários estão ausentes ou em densidades populacionais baixas em determinadas áreas e confirmam que sistemas de polinização mista podem ser vantajosos e ocorrer em plantas aparentemente especializadas, como as bromélias

Data Driven Surrogate Based Optimization in the Problem Solving Environment WBCSim

Large scale, multidisciplinary, engineering designs are always difficult due to the complexity and dimensionality of these problems. Direct coupling between the analysis codes and the optimization routines can be prohibitively time consuming due to the complexity of the underlying simulation codes. One way of tackling this problem is by constructing computationally cheap(er) approximations of the expensive simulations, that mimic the behavior of the simulation model as closely as possible. This paper presents a data driven, surrogate based optimization algorithm that uses a trust region based sequential approximate optimization (SAO) framework and a statistical sampling approach based on design of experiment (DOE) arrays. The algorithm is implemented using techniques from two packages—SURFPACK and SHEPPACK that provide a collection of approximation algorithms to build the surrogates and three different DOE techniques—full factorial (FF), Latin hypercube sampling (LHS), and central composite design (CCD)—are used to train the surrogates. The results are compared with the optimization results obtained by directly coupling an optimizer with the simulation code. The biggest concern in using the SAO framework based on statistical sampling is the generation of the required database. As the number of design variables grows, the computational cost of generating the required database grows rapidly. A data driven approach is proposed to tackle this situation, where the trick is to run the expensive simulation if and only if a nearby data point does not exist in the cumulatively growing database. Over time the database matures and is enriched as more and more optimizations are performed. Results show that the proposed methodology dramatically reduces the total number of calls to the expensive simulation runs during the optimization process

Electrophysiological evidence for altered visual, but not auditory, selective attention in adolescent cochlear implant users

Objective: Selective attention fundamentally alters sensory perception, but little is known about the functioning of attention in individuals who use a cochlear implant. This study aimed to investigate visual and auditory attention in adolescent cochlear implant users

Comment on "Quantum bound states with zero binding energy"

The purpose of this Comment is to show that the solutions to the zero energy Schr\"odinger equations for monomial central potentials discussed in a recently published Letter, may also be obtained from the corresponding free particle solutions in a straight forwardly way, using an algorithm previously devised by us. New solutions to the zero energy Schr\"odinger equation are also exhibited.Comment: Accepted for publication in PHISICS LETTERS

Transverse Compression Behavior of Wood in Saturated Steam at 150-170°C

The transverse compression behavior of wood in high temperature (150, 160, and 170°C) and saturated steam conditions was studied. The effect of the temperature on the stress-strain response, nonlinear strain function, and relative density change was examined by a modified Hooke's law based on the load-compression behavior of flexible foams. The influence of environmental conditions during compression on the set recovery of the compression deformation was determined. It was found that temperature and moisture content affected the compression behavior of wood in saturated steam conditions. A small difference in moisture content of specimens compressed at 160 and 170°C caused approximately the same stress-strain and relative density curves with minimum temperature affect on the compression behavior. The compressive modulus of the wood and cell wall modulus were found to decrease with increasing temperature from 150 to 160°C with no change when increased to 170°C. The densification region was entered at notably lower stress levels at 160 and 170°C when compared with 150°C. The results established that temperature and moisture content did not affect the nonlinear strain function at strain levels lower than 0.63. Furthermore, it was found that the set recovery of compressive deformation decreased with increasing temperature of compression from 150 to 160°C. In addition, the results showed that compression at 160 and 170°C significantly lowered the equilibrium moisture content

Inverse problem for the retarded field of an arbitrary moving charge

It is assumed that the Lienard-Wiechert fields of an arbitrary moving charge is measured or predefined as a function of time. The position of the charge is calculated as a function of the retarded time.Comment: LaTeX2e, 6 pages, published in Physics Letters

Moisture Dependent Softening Behavior of Wood

An improved understanding of material behavior during the manufacture of wood-based composites can increase the efficiency of wood utilization and provide insight into the development of new processes and products that manipulate the viscoelastic nature of wood. One specific area where additional knowledge can be of great benefit is the influence of heat and moisture on the softening behavior of wood.The thermal softening behavior of wood at four moisture levels from 0 to 20% was evaluated using dielectric thermal analysis (DETA). Coincident in situ relaxations attributed to the softening of amorphous wood components in the range of 20 to 200°C were observed and found to exhibit the characteristics of a glass transition. The moisture dependence of this transition was characterized, and differences in the observed Tg were detected between juvenile and mature wood. Time-temperature superposition was also shown to be applicable to the wood and water system

Characteristics of Phenol-Formaldehyde Adhesive Bonds in Steam Injection Pressed Flakeboard

A better understanding of the mechanisms involved in phenol-formaldehyde resin-wood bonding is needed to design adhesive systems that can adequately develop bond strength in a humid environment. This study was performed to determine how the molecular weight distribution of a liquid resole phenol-formaldehyde adhesive affects mechanical properties and adhesive flow in flakeboard bonded during steam injection pressing. The performance of three adhesives, differing only in molecular weight distribution, was studied. For all adhesives, mechanical properties of specimens located on the edge of the panel were found to be superior to those located in the center of the board. Excessive moisture present in the center of the mat was believed to be responsible for poor bonding. Edge internal bond strength improved with higher weight average molecular weight adhesive. Fluorescence microscopy and image analysis techniques were used to measure flow of adhesive into the wood substrate before and after exposure to a steam injection pressing environment. Flakes wetted with adhesive and not exposed to a pressing environment had more adhesive penetration with the lowest weight average molecular weight adhesive. Deeper and less concentrated adhesive penetration was measured in flakes exposed to a steam injection environment, with a smaller apparent difference between the three adhesives