21 research outputs found
Vibration and Noise Exposure during Pre-Commercial Thinning Operations: What Are the Ergonomic Benefits of the Latest Generation Professional-Grade Battery-Powered Chainsaws?
No full textIn order to compare the vibration and noise exposure of STIHL’s battery-powered MSA 220 C and the combustion driven MS 201 C, a professional operator was monitored during a pre-commercial thinning operation in a twenty-year-old hardwood stand. The vibration levels were measured with a tri-axial accelerometer on the front and rear handle of both the chainsaws, and assigned to five different work elements using a video documentation. Additionally, noise levels were recorded in one-minute intervals, with a dosemeter worn by the operator. The results show that battery-powered chainsaws, when compared to combustion-driven chainsaws, can reduce the daily vibration exposure by more than 45% and the noise dose by about 78.4%, during pre-commercial thinning tasks. Replacing combustion-driven chainsaws with battery-powered ones is therefore generally recommended, to reduce occupational health risks for operators, in this respect. However, the daily vibration exposure of about 2.42 m/s2, caused by the battery-powered chainsaw on the front handle, is still very close to the daily exposure action value set by the EU directives for health and safety requirements. The daily noise exposure of 89.18 dB(A) even exceeds the upper exposure action value. Consequently, a further reduction in the vibration exposure during work is desirable. With respect to noise exposure, additional measures must be implemented for conformity with the current safety standards, making the use of hearing protectors mandatory for electric chainsaws, too
Productivity and cost analysis of tower yarder systems using the Koller 507 and the Valentini 400 in southwest Germany
No full textCable-based timber extraction offers some advantages with regard to impacts to forest stands and soils, and can be used under a wide range of conditions. It is important not only in steep terrain, but also increasingly in flat terrain when soils have low bearing capacity. In this study, utilization data from two commonly used tower yarding systems were analyzed: a tower yarder with a mounted processor (K507) and a medium-distance tower yarder (V400). Collected data included explanatory variables, such as the proportion of hardwood timber, length of skyline, direction of yarding and dimension of harvested timber. Data were analyzed with regard to the time required for machine installation including set-up and dismantling, machine productivity and resulting production costs. Possible combinations of machines and partial working steps were evaluated. Results indicated an increasing utilization of cable crane systems in horizontal yarding direction throughout the analyzed time period. Further, more time was required to process full trees when the K507 was used, although machine productivity increased. The proportion of processed timber that was hardwood significantly influenced installation times. Results demonstrated that, if the machines had above average productivity, total costs could be reduced in flat terrain by using a cable crane instead of conducting the extraction by skidders
The Matilda Wilson College Proposal of December 1956: The First Curricular Source for Oakland University
No full textIn November 1956, Matilda Dodge Wilson and Alfred Wilson decided to donate their Meadow Brook Farms estate and $2 million to the state of Michigan for the purpose of founding an educational institution. One month later, an 11-page memo envisioning the nature of the future Michigan State University Oakland (MSUO) emerged from the office of the Michigan State University (MSU) Vice President for Academic Affairs, Thomas Hamilton. The document was the first conceptualization of an academic program for the new institution which became MSUO, although the author called it the Matilda Wilson College
The Books I Wanted to Write
No full textAuthor lists book titles he would have liked to have written and humorous descriptions of them
Considerações sôbre o emprego de variedades sintéticas no melhoramento do milho: I - sintéticos simples
No full text1) Inicialmente foi dado um breve resumo dos métodos básicos do melhoramento no milho os quais podem ser reunidos em dois grupos principais: o processo do milho híbrido, com as suas variantes, e os processos dos sintéticos. Estes últimos podem ainda ser subdivididos em duas categorias: os sintéticos simples e os sintéticos balançados. Na obtenção dos sintéticos simples toma-se inicialmente em consideração a capacidade combinatória das linhagens a serem misturadas, e se executa em cada geração de sintético uma seleção massal de conservação. Nos balançados devemos acrescentar uma forte seleção, na fase preparatória, contra todos os híbridos que dão segregações mendelianas fortes demais. 2) No curso de um breve resumo histórico ficou evidente que a idéia de se aproveitarem os sintéticos no melhoramento do milho, formulada pela primeira vez por Hayes e Garber (1919) deu resultados práticos apreciáveis. Assim Hayes, Rinke e Tsinang (1944) obtiveram produções de sintéticos que eram equivalentes de um híbrido duplo, Minhybrid 403. Lonnquist (1949) registrou produções de sintéticos idênticos ao híbrido duplo, US 13. Roberts, Wellhausen, Palácios e Guaves (1949) e Wellhausen (1950) relataram resultados bastante satisfatórios, obtidos no México. 3) Ficou demonstrado que as fórmulas de Sewall Wright (1932) e de Mangelsdorf (1939) não podem ser consideradas como explicações gerais do método, pois pela sua derivação pode-se mostrar facilmente que elas exigem certas premissas que nem sempre são justificáveis. 4) Para eliminar confusões na terminologia foi desenvolvido um esquema básico da constituição de sintéticos supondo que se parte de linhagens autofecundadas e que foram plantadas em conjunto para a reprodução de cruzamento livre. A geração que consiste das plantas autofecundadas, plantadas em mistura, é denominada SyO. A geração seguinte, a qual contém uma maior percentagem de híbridos simples e uma menor per-centagem de descendentes de cruzamentos dentro de mesma linhagem (descendentes consanguíneos) representa assim a geração Syl. A geração que segue depois de novo cruzamento livre, Sy2, será então composta de híbridos entre quatro linhagens (híbridos duplos"), entre três linhagens ("three way crosses"), entre duas linhagens ("híbridos simples") e descendentes de combinações consanguíneas, ("inbreds"). Porém se houver uma seleção em Sy1 que elimina todos os descendentes de combinações consanguíneas, sobrevivendo apenas híbridos simples, então a geração Sy2 será composta de híbridos entre plantas que não tem nenhuma das linhagens originais em comum, os que têm uma linhagem em comum e finalmente aqueles que têm duas linhagens em comum. 5) Empregando esta classificação das gerações, podemos verificar que a geração Sy1 de Lonnquist corresponde à geração Sy1 do esquema básico, a geração Sy1 deHayes et al corresponde à geração Sy2 do esquema básico é a geração Sy1 de Wellhausen et al corresponde aproximadamente à geração Sy3 do esquema básico. 6) Uma teoria mais correta dos sintéticos deve-se basear nas regras da genética em populações, as quais foram empregadas por Brieger para justificar o processo dos sintéticos balançados. Uma discussão mais detalhada desta teoria será assim dada numa outra publicação que se ocupara especialmente com ossintéticos balançados.1) The author gives a short resume of the principal breeding methods in maize. Since mass selection cannot be considered as a method for improving corn, two groups of methods remain: the hybrid corn method and the method of the synthetics. Reasons are given why it seems important that the latter should be applied, after a further improvement of the breeding technique and its theoreticsl basis. The method may still be subdivided into the method of simple synthetics and of balanced synthetics. In the preparation of the former, only the following two points have to be considered: selection for combining ability before the constitution of the synthetic, and mass selection aganst weak descendants of consanguineous matings after the establishment of the synthetic. In the case of the balanced synthetics, a third element is added: selection against or rather previous elination of all hybrids which give too strong mendelian segregation in a synthetic. 2) The first proposal to use synthetics has been made by Hayes and Gardner in 1919. Positive results were obtained howewer only much later, since before 1940 the importance of selection for combining ability was not recognized. Hayes, Rinke and Tsiang (1944) obtained a synthetic which equalled the double hybrid Minhybrid 403.Lonnquist (1949) obtained a synthetic which eaqulled the double hybrid US13. Roberts, Wellhausen, Palacios and Cuevas (1949), Roberts and Wellhausen (1948) and Wellhausen (1950) reported on satisfatory results from Mexico. Brieger (1944 and later) produced balanced synthetics of subtropical sweet corn. 3) The author demostrates that the formulae of Sewall Wright (1922) and of P. C. Magelsdorf (1939) cannot be used satisfactorily to explain the composition of synthetics. Both these formulae start from certain assumptions which are not allways satisfeid, and disregard the principles of genetics in populations under selection. 4) In oder to avoid confusion in discussions on the theory of synthetics, a basic scheme is proposed for the identficiation of subsequent generations. The first generation of plants, planted out in mixture and left to free pollinisation should be called So. and it should be composed of the offspring of individual selected plants which had suffered at least one selfing or more. The first generation after free pollinisation, or generation Sy1, consists thus mainly of simple hybrids except for some individuals resulting from consanguineous matings between sister plants. If there were no selection, the next generation Sy2 should be composed of individuals from matings between individuals which may have none,, one, two, three or even four lines in their ancestry in common. Howewer if artificial selection against weaker and less productive plants is carried out in the generations Syl and Sy2, than we may assume that only individuals remain from matings wich had from none up to two ancestral lines in common. 5) Using this classification we can say that the generation Syl in Lonnquist\u27s experiment corresponds to the generation Syl of the basic scheme, Syl of Hayes, Rinke and Tsiang correspond to Sy2 of the basic scheme and Syl of the Mexican authors corresponds to a generation of about the order Sy3. 6) A correct theory of synthetics should take fully into consideration the principals of population genetics, taking furthermore into consideration modern theories on the genetic basis of heterosis in maize
Mother and the other: situating New Zealand women's captivity narratives in a transcolonial settler culture of anxiety
No full textThis article analyses nineteenth-century women's captivity narratives in the white settler colony New Zealand. It asks how white femininity and indigenous masculinity are represented and how these notions relate to representations of white masculinity and indigenous femininity. Moreover, the article examines the relationship between colonial gender identities and British bourgeois ideals of respectable gender images. By comparing the New Zealand case with the early modern North American narrative of Mary Rowlandson and the Australian Eliza Fraser stories, the author argues that New Zealand can be included in a transcolonial culture of captivity, as it shares a transcolonial repertoire of discursiverhetorics, strategies and anxieties
United States and the Islam after September 11th.
No full textEl autor focaliza el artículo en las relaciones entre los Estados Unidos y el Islam después de los atentados del 11 de setiembre, señalando la existencia de tres etapas diferentes en la crisis internacional a partir de los atentados de dicha fecha: la primera, "de la victimización a la búsqueda del consenso", seguida por la de "la de la ofensiva militar" y "la de la reconstrucción afgana bajo paraguas de los Estados Unidos". Por último, concluye que desaparecida la Unión Soviética, Estados Unidos ha necesitado redefinir la confrontación a su liderazgo en el escenario internacional. En su estrategia global, se ha planteado la posibilidad de que sean cuatro actores quiénes puedan desafiar el modelo de globalización actual: China, el Islam, los movimientos de resistencia global y el terrorismo global, personificado en Bin Laden. Sin duda el cuestionamiento del Islam a la hegemonía de los EE.UU. le da una nueva impronta a su estrategia hacia Medio Oriente.The author focalises the article on the relations between the United States and Islam after the attack of September 11th, pointing out three stages of the international crisis after this date: "the victimization and fight for consensus", "the military offensive" and "the reconstruction of Afghanistan under the American guidance". He gets to the conclusion that after the disappearance of the Soviet Union, the United States has been needing to redefine the confrontation of its leadership in the international scenery. The States in its global strategy, has thought in the possibility of four actors challenging the current global model "China, Islam and the resistance movements and global terrorism embodied in Bin Laden". And there is no doubt that the issues of Islam and the American hegemony give a new turn in the American strategy toward Middle East.Instituto de Relaciones Internacionales (IRI
Estados Unidos y el islam después del 11 de setiembre.
No full textEn españolEl autor focaliza el artículo en las relaciones entre los Estados Unidos y el Islam después de los atentados del 11 de setiembre, señalando la existencia de tres etapas diferentes en la crisis internacional a partir de los atentados de dicha fecha: la primera, "de la victimización a la búsqueda del consenso", seguida por la de "la de la ofensiva militar" y "la de la reconstrucción afgana bajo paraguas de los Estados Unidos". Por último, concluye que desaparecida la Unión Soviética, Estados Unidos ha necesitado redefinir la confrontación a su liderazgo en el escenario internacional. En su estrategia global, se ha planteado la posibilidad de que sean cuatro actores quiénes puedan desafiar el modelo de globalización actual: China, el Islam, los movimientos de resistencia global y el terrorismo global, personificado en Bin Laden. Sin duda el cuestionamiento del Islam a la hegemonía de los EE.UU. le da una nueva impronta a su estrategia hacia Medio Oriente.En inglésThe author focalises the article on the relations between the United States and Islam after the attack of September 11th, pointing out three stages of the international crisis after this date: "the victimization and fight for consensus", "the military offensive" and "the reconstruction of Afghanistan under the American guidance". He gets to the conclusion that after the disappearance of the Soviet Union, the United States has been needing to redefine the confrontation of its leadership in the international scenery. The States in its global strategy, has thought in the possibility of four actors challenging the current global model "China, Islam and the resistance movements and global terrorism embodied in Bin Laden". And there is no doubt that the issues of Islam and the American hegemony give a new turn in the American strategy toward Middle East
United States and the Islam after September 11th.
No full textEl autor focaliza el artículo en las relaciones entre los Estados Unidos y el Islam después de los atentados del 11 de setiembre, señalando la existencia de tres etapas diferentes en la crisis internacional a partir de los atentados de dicha fecha: la primera, "de la victimización a la búsqueda del consenso", seguida por la de "la de la ofensiva militar" y "la de la reconstrucción afgana bajo paraguas de los Estados Unidos". Por último, concluye que desaparecida la Unión Soviética, Estados Unidos ha necesitado redefinir la confrontación a su liderazgo en el escenario internacional. En su estrategia global, se ha planteado la posibilidad de que sean cuatro actores quiénes puedan desafiar el modelo de globalización actual: China, el Islam, los movimientos de resistencia global y el terrorismo global, personificado en Bin Laden. Sin duda el cuestionamiento del Islam a la hegemonía de los EE.UU. le da una nueva impronta a su estrategia hacia Medio Oriente.The author focalises the article on the relations between the United States and Islam after the attack of September 11th, pointing out three stages of the international crisis after this date: "the victimization and fight for consensus", "the military offensive" and "the reconstruction of Afghanistan under the American guidance". He gets to the conclusion that after the disappearance of the Soviet Union, the United States has been needing to redefine the confrontation of its leadership in the international scenery. The States in its global strategy, has thought in the possibility of four actors challenging the current global model "China, Islam and the resistance movements and global terrorism embodied in Bin Laden". And there is no doubt that the issues of Islam and the American hegemony give a new turn in the American strategy toward Middle East.Instituto de Relaciones Internacionales (IRI
