Rank 3 extensions of Frobenius groups

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33888/1/0000153.pd

Accuracy investigation in the modeling of partially shaded photovoltaic systems

Software for simulation of photovoltaic (PV) systems is widely used for dimensioning and forecasting electrical production. A factor of losses in PV installations is the partial shading caused by surrounding elements, and these software allow the user to estimate this effect. However, the accuracy of these simulated results for shaded PV systems is not widely studied. The purpose of this article is to investigate the accuracy and quantify the differences between simulated and measured data of partially shaded PV systems, obtained with the widely used tools SAM and PVSyst. Measured data from a PV installation were compared to results from simulations performed using the different shading calculation options available in both tools. The simulated outputs were both underestimated and overestimated in the shading situations. This variation was related to the use of an hourly fraction of shading and, in the case of SAM, due to the limitations of the 3D tools available for representation. Another source of differences between simulated and measured values was the use of uniform shading factors for diffuse and albedo. In addition, the simplification of the 3D model had a significant impact on the predicted energy, mainly on cloudy days. Both software overestimated the electricity production for the entire measurement period, reaching differences between the predicted and the measured energy varying from 9% to 24%. Shaded PV systems must be carefully analyzed, and the simulated results may differ from the measured values, which may even influence the decision on the feasibility of an installation

Crescimento e desenvolvimento de mudas de erva-mate associadas a diferentes coberturas vegetais de inverno

The lack of knowledge of management in the application of yerba mate is the reason for the present study, given the economic importance of this crop for family farming, the economy and also the culture in the southern region of Brazil. The objective of this work was to evaluate the effects of winter cover species on the morphophysiological characteristics of yerba mate seedlings. The experimental design was laid out in randomized blocks with four replicates. The weed species used were Avena strigosa, Lolium multiflorum, Vicia sativa, Raphanus sativus, Lupinus albus, Axonopus catharinensis, the consortium between A. strigosa and V. sativa, and the control treatment without cover. Physiological (photosynthesis, stomatal conductance, transpiration, internal CO2 concentration, water use efficiency, carboxylative efficiency, and chlorophyll) and morphological (plant height, stem diameter, leaf area, shoot and of root dry matter, in addition to cover dry matter) were evaluated. There was competition between the crop and the cover plants for the factors of light and water, and the control without cultivation did not affect the morphophysiological characteristics of yerba mate. The species A. catharinensis proved to be the best cover plant because it competed less with yerba mate. The growth and development of yerba mate were affected by the presence of A. strigosa.La escasez de conocimientos sobre el manejo en la aplicación de la yerba mate es la justificación del presente estudio, dada la importancia económica de este cultivo para la agricultura familiar, la economía y también para la cultura de la región sur de Brasil. El objetivo de este trabajo fue evaluar los efectos de especies de cobertura invernal sobre las características morfofisiológicas de plántulas de yerba mate. El diseño experimental fue en bloques al azar con cuatro repeticiones. Las especies de malezas utilizadas fueron Avena strigosa, Lolium multiflorum, Vicia sativa, Raphanus sativus, Lupinus albus, Axonopus catharinensis, el consorcio entre A. strigosa y V. sativa, y el tratamiento testigo sin cobertura. Se evaluaron las características fisiológicas (fotosíntesis, conductancia estomática, transpiración, concentración interna de CO2, eficiencia en el uso del agua, eficiencia de carboxilo y clorofila) y morfológicas (altura de la planta, diámetro del tallo, área foliar, parte aérea y materia seca de la hoja). a la materia seca de la cubierta) de las plantas. Hubo competencia entre el cultivo y los cultivos de cobertura por los factores luz y agua, y el testigo sin cultivo no afectó las características morfofisiológicas de la yerba mate. La especie A. catharinensis demostró ser la mejor planta de cobertura porque compite menos con la yerba mate. El crecimiento y desarrollo de la yerba mate se vieron afectados por la presencia de A. strigosa.A escassez de conhecimento sobre o manejo na aplicação da erva-mate é a justificativa do presente estudo, haja vista a importância econômica desta cultura para a agricultura familiar, economia e também para a cultura da região sul do Brasil. O objetivo deste trabalho foi avaliar os efeitos de espécies de cobertura de inverno sobre as características morfofisiológicas de mudas de erva-mate. O delineamento experimental foi em blocos casualizados com quatro repetições. As espécies daninhas utilizadas foram Avena strigosa, Lolium multiflorum, Vicia sativa, Raphanus sativus, Lupinus albus, Axonopus catharinensis, o consórcio entre A. strigosa e V. sativa, e o tratamento controle sem cobertura. Foram avaliadas as características fisiológicas (fotossíntese, condutância estomática, transpiração, concentração interna de CO2, eficiência do uso da água, eficiência carboxilativa e clorofila) e morfológicas (altura da planta, diâmetro do caule, área foliar, matéria seca da parte aérea e da raiz, além da matéria seca da cobertura) das plantas. Houve competição entre a cultura e as plantas de cobertura pelos fatores de luz e água, e o controle sem cultivo não afetou as características morfofisiológicas da erva-mate. A espécie A. catharinensis mostrou-se a melhor planta de cobertura por competir menos com a erva-mate. O crescimento e desenvolvimento da erva-mate foram afetados pela presença de A. strigosa

Neuronal pentraxins mediate synaptic refinement in the developing visual system

Peer reviewedPublisher PD

CuI/glycerol mediated stereoselective synthesis of 1,2-bis-chalcogen alkenes from terminal alkynes: synthesis of new antioxidants

Abstract(E)-1,2-Bis-chalcogen alkenes were stereoselectively prepared in good yields by the addition of diorganyl dichalcogenides to terminal alkynes using CuI/Zn/glycerol as a recyclable catalytic system. The antioxidant activity in vitro of four (E)-1,2-bis-chalcogen alkenes synthesized was evaluated and (E)-1,2-bis-(4-methoxyphenylselanyl)styrene 3b presented excellent activity. The catalytic system used in the synthesis was recovered and used directly up to 5 cycles without loss of activity

The links between knowledge management structures and national culture: A comparative study of apple users in Italy and Brazil

Knowledge management structures (KMs) can be defined as structures whose purpose is to encourage people to build relationships, networks and trust. Global companies like Apple, Inc. have promoted these structures to transform its organisation into a knowledge-based organisation. This paper identifies the role of national culture on four KMs namely open-mindedness (OM), counter-knowledge (CK), environmental innovation (EF) and customer capital (CC). In doing so, this study uses data collected from 354 end users of Apple (161 from Italy and 193 from Brazil). This paper provides evidence that while Apple end users from Brazil are more positively associated with higher levels of OM and CC, Italy users are more positively associated with higher levels of CK and EF. This paper discusses the role of the six dimensions of national culture–power distance, individualism, masculinity, uncertainty avoidance, long-term orientation and indulgence of a nation that plays a significant role in how they impact the KMs. Hence, this study serves as an important contribution to global companies that are trying to develop their KMs to sustain competitive advantages

Eficácia e fitotoxicidade de herbicidas aplicados para manejo de plantas daninhas infestantes do trigo

The objective of this paper was to identify alternatives for the chemical handling of weeds that infect wheat, as well as verifying the phytotoxicity of herbicides on the crop. The experiment was carried out in randomized blocks, organized in a factorial design of 2x 13, with four repetitions. The wheat crops were allocated to factor A (Quartzo and Pioneiro) and the herbicides to factor B (iodosulfuron – 0,100 kg ha-1; imazapic + imazapyr – 0,140 kg ha-1; clomazone 0,800 L ha-1; imazethapyr + imazapic – 1,250 L ha-1; propanil – 6,000 kg ha-1; oxyfluorfen – 1,000 L ha-1; penoxsulam – 0,175 L ha-1; metsulfuron-methyl – 0,0033 kg ha-1; 2,4-D – 1,250 L ha-1; cyhalofop-p-buthyl – 1,380 L ha-1; pyroxsulam – 0,400 L ha-1), plus two controls, one weeded and another one infested. Iodosulfuron, propanil, oxyfluorfen, metsulfuron-methyl, 2,4-D, cyhalofop-p-buthyl, penoxsulam and pyroxsulam cause values inferior to 5.5% of phytotoxicity to wheat crops and, in general, they did not differ from the weeded and infested controls. The greatest phytotoxic effects were caused by imazethapyr + imazapic, clomazone and imazapic + imazapyr on the wheat crops. The application of iodosulfuron, imazethapyr + imazapic, imazapic + imazapyr and pyroxsulam presented elevated control percentage of ryegrass, with rates above 95.5%. Imazethapyr + imazapic, clomazone and imazapic + imazapyr presented the greatest phytotoxicity on the wheat crops. Iodosulfuron, imazethapyr + imazapic, clomazone and imazapic + imazapyr and pyroxsulam showed the best controls for ryegrass. Iodosulfuron presented lower influence on the components of wheat grains yield when compared to the other herbicides.Objetivou-se com o trabalho identificar alternativas para o manejo químico de plantas daninhas infestante do trigo, bem como verificar a fitotoxicidade de herbicidas sobre a cultura. Instalou-se o experimento em blocos casualizados, arranjado em esquema fatorial 2 x 13, com quatro repetições. No fator A, alocou-se as cultivares de trigo (Quartzo e Pioneiro) e no B os herbicidas (iodosulfuron – 0,100 kg ha-1; imazapic + imazapyr – 0,140 kg ha-1; clomazone 0,800 L ha-1; imazethapyr + imazapic – 1,250 L ha-1; propanil – 6,000 kg ha-1; oxyfluorfen – 1,000 L ha-1; penoxsulam – 0,175 L ha-1; metsulfuron-methyl – 0,0033 kg ha-1; 2,4-D – 1,250 L ha-1; cyhalofop-p-buthyl – 1,380 L ha-1; pyroxsulam – 0,400 L ha-1), mais duas testemunhas uma capinada e outra infestada. O iodosulfuron, propanil, oxyfluorfen, metsulfuron-methyl, 2,4-D, cyhalofop-p-buthyl, penoxsulam e pyroxsulam ocasionaram valores inferiores a 5,5% de fitotoxicidade às cultivares de trigo e de modo geral não diferiram das testemunhas capinada e infestada. Os maiores efeitos fitotóxicos foram ocasionados pelo imazethapyr + imazapic, clomazone e imazapic + imazapyr sobre as cultivares de trigo. A aplicação de iodosulfuron, imazethapyr + imazapic, imazapic + imazapyr e o pyroxsulam apresentaram elevados percentuais de controle do azevém, com índices superiores a 95,5%. O imazethapyr + imazapic, clomazone e imazapic + imazapyr apresentaram as maiores fitotoxicidades sobre as cultivares de trigo. O iodosulfuron, imazethapyr + imazapic, clomazone e imazapic + imazapyr e o pyroxsulam demonstraram os melhores controles do azevém. O iodosulfuron apresentou a menor influência sobre os componentes do rendimento de grãos do trigo ao se comparar com os demais herbicidas