Why Trade Associations Matter: Exploring Function, Meaning, and Influence

We explore the organizational characteristics of trade associations (TAs) and suggest theoretical approaches for undertaking research into or involving TAs in management and organization studies. Through emphasizing the role of TAs within and between industries and at the interface of business and society, we consider how TAs generate meaning and influence

Experimentos sobre a influência de Chaoborus brasiliensis (Diptera: Chaoboridae) sobre a migração vertical de microcrustáceos do Lago Monte Alegre, Brasil

The aim of this work was to evaluate whether diel vertical migration of microcrustaceans from Lake Monte Alegre is related to invertebrate predators, namely larvae of Chaoborus brasiliensis. The hypothesis tested in the experiments was that the migratory behaviour of prey would depend on physical contact with Chaoborus brasiliensis larvae or with kairomones released by them. Two experiments were undertaken in the laboratory, with two treatments and three replicates each. Experiments were carried out in acrylic cylinders 1.5 m high and 0.20 m in diameter. Treatments in Experiment I were: A) predator and kairomones present and B) predator and kairomones present, but predator isolated in net tube inside the cylinder, having no physical contact with prey. Treatments in Experiment II were: A) predator and kairomones absent and B) the same as in experiment I. Physical and chemical factors (temperature, dissolved oxygen, pH, electrical conductivity) and food (algae) did not influence vertical distribution of prey, as they were almost homogeneously distributed in the water column in both experiments; food concentrations were not limiting. Adult copepods (Tropocyclops prasinus meridionalis and Thermocyclops decipiens) showed reverse migration in the treatment B of both experiments; the cladoceran Daphnia gessneri migrated nocturnally in the treatment A of the Experiment I; vertical migration was undetectable for copepodites, as well as for Chaoborus larvae. The experiments indicated that Daphnia responded to physical contact with Chaoborus larvae but not to kairomones alone. Adult copepods seemed to be more sensitive to kairomones.O objetivo deste trabalho foi avaliar se a migração vertical dos microcrustáceos do Lago Monte Alegre é relacionada aos predadores invertebrados, nomeadamente larvas de Chaoborus brasiliensis. A hipótese testada no experimento foi a de que o comportamento migratório da presa seria dependente do contato físico com as larvas de Chaoborus ou dos "kairomones" liberados por elas. Dois experimentos foram realizados no laboratório, com dois tratamentos e três réplicas cada. Os experimentos foram feitos dentro de cilindros de acrílico de 1,5 m de altura e 0,20 m de diâmetro. Os tratamentos do Experimento I foram: A) predador e "kairomones" presentes e B) predador e "kairomones" presentes, mas o predador isolado em tubos de rede dentro do cilindro, não tendo contato físico com a presa. Os tratamentos do Experimento II foram: A) predador e "kairomones" ausentes e B) igual ao Experimento I. Fatores físicos e químicos (temperatura, oxigênio dissolvido, pH, condutividade elétrica) e alimento (algas) não influenciaram a distribuição vertical das presas, pois eles estavam quase homogeneamente distribuídos na coluna d'água em ambos os experimentos; as concentrações de alimento não foram limitantes. Copépodos adultos (Tropocyclops prasinus meridionalis e Thermocyclops decipiens) realizaram migração reversa no tratamento B dos dois experimentos; o cladócero Daphnia gessneri migrou de modo noturno no tratamento A do Experimento I; migração vertical não foi detectada para copepoditos, bem como para larvas de Chaoborus. Os experimentos indicaram que Daphnia respondeu ao contato físico com as larvas de Chaoborus e não aos "kairomones". Copépodos adultos foram aparentemente mais sensíveis aos "kairomones"

Vibrations of cable-suspended rehabilitation robots

Rehabilitation robots help the treatment of diseases by performing cyclic exercises for a long period of time. These exercises must perform movements of the patient's limbs; thus, the robots are required to be flexible and safe. Among rehabilitation robots, cable robots are widely used due to their unique properties, such as being lightweight and the possibility of being equipped with magnetic hooks to improve both safety and ease of use. However, the elasticity and flexibility of cables result in vibrations of the payload and hooks. In this paper, the forced vibrations due to rehabilitation exercises are studied. Since the previous studies of the authors showed a weak coupling between longitudinal and transverse vibrations, a two-cable planar model for the study of transverse vibrations is developed. The model makes it possible to study the forced transverse vibrations due to both cable motion and robot motion. Stiffness and damping of the patient's arm are considered. Results show that the cable system exhibits a simple linear behavior when excited by robot motion and a non-linear behavior when excited by cable motion

Surfactant-aided catalytic copolymerization of carbon monoxide with ethene in water as a solvent

The perfectly alternated ethene-carbon monoxide co-polymerisation to poly(1-oxotrimethylene) was in the last decade an important topic in the field of catalysis [1]. Since we have focalized our research on the influence of solvent on this reaction [2], we are also interested to study the possibility to use green solvents such as water. In fact, water is cheap, readily available, non-toxic, non-flammable, and safe to environment [3]. The use of water may be interesting for many other reasons, in particular for the possibility to obtain very high molecular weight polymers [2]. The catalytic polymerization is efficiently carried out in methanol by using the [Pd(OAc)2(DPPP)] complex in the presence of an acid (ptoluenesulfonic, TsOH) [1]. By replacing methanol with water it is necessary to use the more expensive but solvable [Pd(OAc)2(DPPP-S)] complex as precursor (DPPP–S is the sulfonated ligand) [4]. As an alternative to the sulfunated ligand we propose to carry out the catalysis in water with the aid of surfactants. Here we report our preliminary results on the preparation of alt- poly(1-oxo-trimethylene) by using the [Pd(OAc)2(DPPP)] complex in water containing a surfactant above the critical micelle concentration. The performance of various surfactants are highlighted

Changes in the size structure of marine fish communities

Marine ecosystems have been heavily impacted by fishing pressure, which can cause major changes in the structure of communities. Fishing directly removes biomass and causes secondary effects such as changing predatory and competitive interactions and altering energy pathways, all of which affect the functional groups and size distributions of marine ecosystems. We conducted a meta-analysis of eighteen trawl surveys from around the world to identify if there have been consistent changes in size-structure and life history groups across ecosystems. Declining biomass trends for larger fish and invertebrates were present in nine systems, all in the North Atlantic, while seven ecosystems did not exhibit consistent declining trends in larger organisms. Two systems had alternative patterns. Smaller taxa, across all ecosystems, had biomass trends with time that were typically flat or slightly increasing. Changes in the ratio of pelagic taxa to demersal taxa were variable across the surveys. Pelagic species were not uniformly increasing, but did show periods of increase in certain regions. In the western Atlantic, the pelagic-to-demersal ratio increased across a number of surveys in the 1990s and declined in the mid 2000s. The trawl survey data suggest there have been considerable structural changes over time and region, but the patterns are not consistent across all ecosystems

Sistema de criptografia simétrica via porta lógica quântica.

Atualmente, a teoria relacionada à criptologia é fortemente baseada na hipótese de unidirecionalidade de caminhos computacionais. Esta conjectura matemática sustenta que deve haver uma função bijetora para a qual o cálculo em uma direção é fácil, enquanto reconstruir o estado de entrada a partir do estado de saída é difícil - ?fácil? e ?difícil? devem ser entendidas no sentido de complexidade computacional.bitstream/item/138134/1/ComTec119-criptografia.pd

The performance of modified asphalt mixtures with different lengths of glass fiber

One practical option for modifying an asphalt mixture's performance is to use additives. This will help the mixture perform better against the damaging effects of traffic, loads, and climatic variations. In this regard, glass fiber (GF) has drawn much interest because of its positive effect. Therefore, this paper attempts to study the effect of glass fiber length and content on the performance and strength of asphalt mixtures. It also aims to determine the optimum glass fiber content and the best glass fiber length of modified asphalt mixtures. An experimental program is carried out, which includes the Marshall test, volumetric properties, freeze-thaw splitting test, immersion Marshall test, and wheel tracking test to characterize related properties of glass fiber incorporated in asphalt mixtures. Seven different percentages (0, 0.25, 0.5, 0.75, 1, 1.25, and 1.5) of glass fiber by total weight of aggregates in three various lengths are used to design 19 asphalt mixtures. Based on the results obtained, the performance of the asphalt mixture was enhanced remarkably after adding glass fiber. The use of various lengths of glass fiber led to a better-quality asphalt mixture in terms of volumetric properties, moisture damage resistance, and permanent deformation resistance. Specifically, asphalt mixtures made with (0.5%) glass fiber illustrated the highest quality, and adding (20 mm) length of glass fiber was better than (10 mm and 30 mm) glass fiber lengths. The results also show that adding (10 mm and 30 mm) lengths of glass fiber can improve the resistance of asphalt mixtures to water damage and permanent deformation compared with the control mixture (M0). The findings indicate the applicability of 20 mm glass fiber length in asphalt mixtures to achieve better resistance against moisture and reduce the chance of irreparable permanent deformation under growing traffic loads and hot climate changes. Although the inclusion of glass fiber in asphalt mixtures led to a modest increase (6%) in overall cost, the effective improvement in performance and extension of the service life of the asphalt pavement constitute a convincing argument for this approach, making it an attractive option. Finally, it was concluded that a higher amount of glass fiber (i.e., > 0.5%) and a length greater than (20 mm) could diminish the positive effect of glass fiber to improve the properties of glass fiber asphalt mixtures

Protótipo de sistema de segurança criptográfica via porta lógica quântica.

O cifrador XOR não é considerado completamente seguro, pois não há chaves de criptografia verdadeiramente aleatórias, dado que as chaves são geradas em geradores de números pseudorrandômicos a partir de sementes que não podem ser negligenciadas. No entanto, uma chave que destrói a própria semente que a gerou, pode ser considerada verdadeiramente aleatória, pois o seu estado inicial é definitivamente ignorado. Neste trabalho, nós apresentamos um modelo de chaves verdadeiramente aleatórias que podem ser obtidas a partir da porta quântica denominada controlled-NOT (CNOT) usada para emaranhar estados EPR