Principal components analysis applied to flotation of iron ore.

A flota??o ? um processo de concentra??o, usualmente, empregado no beneficiamento do min?rio de ferro. O presente trabalho teve como objetivo avaliar a influ?ncia de vari?veis no processo de flota??o em bancada utilizando a t?cnica de an?lise de componentes principais. Para isso, realizou-se uma an?lise estat?stica com o aux?lio do software R, onde foram estudados os teores de s?lica e ferro na alimenta??o, no concentrado e no rejeito, teores dos contaminantes na alimenta??o (lama, ?xido de c?lcio e ?xido de magn?sio), perda por calcina??o e dosagem de amina. Por meio da an?lise foi poss?vel concluir que as duas primeiras componentes explicaram juntas aproximadamente 45% da variabilidade total da matriz de dados. A primeira componente explicou em torno de 25% da vari?ncia, sendo relacionada com a perda de seletividade do processo de flota??o. J? a segunda componente explicou cerca de 20% da vari?ncia e descreveu a inefici?ncia do processo. Atrav?s dos estudos realizados, foi poss?vel observar que a t?cnica de an?lise de componentes principais pode ser utilizada para melhor entendimento das vari?veis dos processos de flota??o em bancada.Flotation is a process of concentration, usually, employed in iron ore processing. The present work aimed to evaluate the influence of variables in the flotation process in the bench-scale using the principal components analysis technique. For this purpose, a statistical analysis by using the software R was carried out, studying the silica and the iron contents in the feed, in the concentrate and in the tailings as well as the contaminants (mud, calcium oxide and magnesium oxide) in the feed and also the loss on ignition and amine dosing. The analysis has allowed to conclude that the first two components together account for approximately 45% of the total variability of the data matrix. The first component explained about 25% of the variance, related to the loss of selectivity of the flotation process. The second component explained about 20% of the variance and described the inefficiency of the process. The conducted studies have shown that the principal components analysis technique can be used to a better understanding of the variables of the bench-scale flotation processes

Preparation and grain silage processing wet corn in feed

Todos os textos, informa??es e resultados apresentados s?o de inteira responsabilidade dos autores.Objetivou-se a partir desse trabalho apresentar uma revis?o da literatura sobre, o processamento de silagem de gr?o ?mido de milho na alimenta??o animal. Visto que o gr?o do milho ? a principal fonte de energia para ruminantes e monog?stricos. O planejamento ? o primeiro passo para alcan?ar a produ??o de qualidade da silagem. Os mesmo cuidados da ensilagem da planta inteira s?o imprescind?veis para o processamento da ensilagem apenas de gr?os. Na t?cnica da ensilagem, s?o adotadas estrat?gias como o dimensionamento do silo adequado, rapidez no momento da colheita; transporte e moagem; compacta??o necess?ria para acomodar com efici?ncia as part?culas do material; agilidade na veda??o do silo e seu uso durante o fornecimento aos animais. Cada vez mais pesquisas v?m confirmando utiliza??o da silagem de gr?o ?mido de milho como um importante componente energ?tico da dieta para a maioria das esp?cies de interesse zoot?cnico. Considerando que elabora??o e processamentos da silagem de gr?o ?mido de milho ? uma tecnologia que pode contribuir de forma significativa a fim de melhorar os ?ndices de produtividade dos animais. Entretanto seu uso ainda e considerado incipiente no pais, com necessidade de novos estudos em sua utiliza??o em rela??o as dificuldades de processamento e fornecimento aos animais.The objective was to work from that present a literature review on the processing of wet grain corn silage for animal feed. Since the grain of corn is the primary source of energy for ruminants and monogastrics. Planning is the first step to achieve the production of silage quality. The same care of the whole plant silage are essential for processing silage only beans. In ensiling technique, strategies are adopted as designing the appropriate silo, speed at the time of harvest; Transport and crushing; compression required to efficiently accommodate the particles of the material; agility in the sealing of the silo and its use in animal feeding. Increasingly research have confirmed use of silage moisture corn as a major energy component of the diet for most livestock species. Whereas the preparation and processing of silage moisture corn is a technology that can significantly contribute to improve animal productivity. However its use is considered still incipient in the country, in need of new studies on its use in relation to the difficulties of processing and animal feeding

Milk production systems retated momba?a grass

Todos os textos, informa??es e resultados apresentados s?o de inteira responsabilidade dos autores.A produ??o animal em pastagens apresenta vantagens em rela??o aos outros sistemas de produ??o. Geralmente, o pasto ? o alimento mais vi?vel economicamente para a alimenta??o de ruminantes. O capim-momba?a ? uma cultivar de Panicum maximum nativa da ?frica, essa cultivar apresenta desenvolvimento satisfat?rio em sistemas de manejo mais intensivos e com altas taxas de lota??o. Por?m, para garantir a produtividade animal, a fisiologia da forrageira deve ser respeitada com auxilio das alturas de entrada de sa?da adequadas a cada esp?cie.Livestock production in pastures has advantages over other production systems. Generally, the grass is the most economically viable food for feeding to ruminants. The momba?a is a cultivar of Panicum maximum native to Africa, this cultivar has developed satisfactorily in more intensive management systems and high stocking rates. However, to ensure animal productivity, forage physiology must be respected with the aid of input output heights appropriate to each species

My partner wants a child: A cross-sectional study of the determinants of the desire for children among mutually disclosed sero-discordant couples receiving care in Uganda

<p>Abstract</p> <p>Background</p> <p>The percentages of couples in HIV sero-discordant relationships range from 5 to 31% in the various countries of Africa. Given the importance of procreation and the lack of assisted reproduction to avoid partner transmission, members of these couples are faced with a serious dilemma even after the challenge of disclosing their HIV status to their spouses. Identifying the determinants of the decision to have children among sero-discordant couples will help in setting reproductive intervention priorities in resource-poor countries.</p> <p>Methods</p> <p>We conducted a survey among 114 mutually disclosed sero-discordant couples (228 individuals) receiving HIV care at four centres in Greater Kampala, between June and December 2007. The data we collected was classified according to whether the man or the woman was HIV-positive. We carried out multivariate logistic regression modelling to determine factors (age, gender, and the influences of relatives and of health workers, ART knowledge, and disclosure) that are independently associated with a desire for children.</p> <p>Results</p> <p>The majority, 59%, of the participants, desired to have children. The belief that their partner wanted children was a major determinant of the desire to have children, irrespective of the HIV sero-status (adjusted odds ratio 24.0 (95% CI 9.15, 105.4)). Among couples in which the woman was HIV-positive, young age and relatives' expectations for children were significantly associated with increased fertility desire, while among couples in which the man was positive; knowledge of ART effectiveness was associated with increased fertility desire. Availability of information on contraception was associated with decreased fertility desire.</p> <p>Conclusions</p> <p>The gender of the positive partner affects the factors associated with a desire for children. Interventions targeting sero-discordant couples should explore contraceptive choices, the cultural importance of children, and partner communication.</p