Several hypotheses have been offered to explain the mechanisms involved in incubation, the phenomenon in which resolution of a problem benefits more from interruption than continuous solution attempts. The predictions of three hypotheses were tested by varying the level of attention demanded by an incubation task. It was found that a task that requires a moderate amount of attention leads to the greatest resolution of the problem during distraction and incubation intervals. This result supports the Withdrawal of Attention hypothesis of incubation and is inconsistent with the predictions of the Incremental Work and Forgetting Fixation hypotheses.

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No description available.

Finding the genes that underlie variation in production and developmental traits has important economic applications. Incubation behaviour represents a loss of production in conventional breeds of chicken adapted to local conditions and was what motivated this thesis. The Mendelian traits of comb type, crest, Silkie and normal feathers, feathered leg, fibromelanosis, comb colour, skin and shank colour, feather colour and patterns are of interest because of the insight they give to genes and development and were also investigated in the thesis. We used White Leghorn and Silkie lines of chicken to detect the genetic loci controlling incubation behaviour and Mendelian traits using linkage based analysis in an F2 cross. The evidence for QTL affecting incubation status over the whole period on chromosome 5 was strong (P<0.05). After the addition of 218 new informative SNP markers across the genome including chromosome 5 the 95% confidence interval spanned a region around 45 cM having previously been 95 cM. Three other suggestive QTL for incubation status were found after the addition of SNP markers on chromosome 1, 18, 19, E22C19W28 at 70, 0, 1 and 13cM respectively. The mode of action of the incubation status QTL indicates that the White Leghorn allele was either promoting incubation behaviour or that heterozygotes have performance that exceeds the homozygotes except the QTL on chromosome 1 where the Silkie allele is promoting incubation behaviour as might be expected. A highly significant QTL (P<0.01) for early incubation behaviour (25-30 weeks) was found on chromosome 8 at 18 cM. This QTL has an additive effect with the possession of a Silkie allele increasing the likelihood of incubation behaviour. Other suggestive QTL for early incubation behaviour were found on chromosome 26 and 1 at 0 and 66cM respectively. For Mendelian traits, genome wide significant (P<0.01) genetic loci for comb type, crest type and feather type was found on chromosome 7 at 77cM, linkage group E22C19W28 at 7cM and on chromosome 3 at 169cM respectively. Significant genetic loci (P<0.01) for leg colour and skin colour were found on chromosome 20 at 56cM and 60cM respectively. In the present study, loci for all feather patterns were found on E22C19W28 even after removing animals carrying the dominant white alleles, suggesting dominant white or another allele at the locus was still influential. Comb type and incubation behaviour were investigated at the gene level. Thyroid stimulating hormone receptor (TSHR) is believed to be involved in the process of domestication and was found at the peak position of the most significant QTL on chromosome 5 for incubation behaviour. Functional exploration of Wnt genes as a candidate gene for comb type was investigated by in-situ hybridization in Silkie and White Leghorn embryos. The Wnt6 gene showed expression in the region of the presumptive comb development of embryos. In conclusion, for the first time genetic loci that explain maternal behaviour have been described. The coincidence of the incubation behaviour locus on chromosome 5 with the site of the strongest selective sweep in poultry, the TSHR, and the coincidence of QTL on chromosome 1 and 8 with thyroid hormone activity it would appear that the thyrotrophic axis may be critical to the loss of incubation behaviour and improved reproductive performance with domestication. Further analysis of these loci should be able to produce markers that can reduce the propensity for birds to incubate. Comb type marker might allow introgression of this trait to prevent comb damage in commercial hens.

The microbiology of nitrification has been extensively studied, but the ecology and environmental impact of the process has received less attention. The reason for this has more to do with the difficulties of conducting field experiments to examine the links with other processes which cause losses of nitrogen, than a failure to appreciate its importance in agricultural systems. This project was designed to overcome some of the limitations of existing field techniques to enable simultaneous measurements of nitrification and the major processes of N supply (mineralization) and N loss (denitrification and leaching) to be examined. The study proceeded in three distinct phases: firstly, soils with contrasting N management histories were examined, using laboratory assays for potential activities. Clear differences which resulted from higher N inputs were established, with correspondingly higher nitrifying activities. For example, in a fertilized soil, mmoniaoxidizers produced 48.4 compared with 1.3 nM NO2- g-1 soil h-1 in an unfertilized soil. Potential nitrite-oxidizing rates were 93.4 and 62.5 nM g-1 h-1, respectively. Assays of enzyme kinetics, therefore confirmed the higher nitrifying activity in the fertilized soil, but demonstrated a lower affinity of the enzyme for N02 substrate, with Km values of 436 and 310 gM NO2--N, respectively. Nitrifying rates in soils from grass-clover swards were intermediate between the fertilized and unfertilized soils. Secondly, a new field incubation technique was developed and used to obtain actual rates by concurrent measurements of the major N cycling processes. A strong correlation was established between nitrification and denitrification (r2 = 0.98). The measurements were verified by comparison with other independent methods. Net rates of nitrification in the same soil type ranged from 0.55 - 1.17 kg N ha-1 d-1, with the highest rates in the fertilized soil. Over 70% of the mineralized N was nitrified, of which 80% was subsequently lost (i. e. either denitrified or leached). Thirdly, the practical implications of these findings were examined in greater detail using 15N labelling techniques which enabled process rates (net and gross) to be established in a model of the N cycle. When nitrification was inhibited, there were no significant differences between gross or net mineralization rates in the soils from the three swards, which indicated that N-immobilization could be directly influenced by the level of nitrifying activity in these soils. The influence of nitrification in determining the pathways of N loss from grassland soils was quantified in this study. From a detailed investigation of the processes involved in N cycling, it was deduced that nitrification was also one of the major factors in determining the outcome of competition for inorganic N between plant and microbial biomasses.

An insightful solution to a problem may be promoted by temporarily being away from the problem at hand and engaging in other tasks or problems. Wallas (1926) conceptualized such an interruption period between problem solving activities as an incubation period. The present study examines the effect of such activities that are provided as an incubation period in computer-based problem solving tasks. In addition, this study explores the potential interaction between the type of problems and the type of interruption tasks involving two types of problems (verbal and spatial) and two types of interruption activities (verbal and spatial). One hundred eighty five undergraduate volunteers participated. The participants were randomly assigned to one of the six conditions, Spatial Problems: No-Interruption Task, Spatial Problems: Verbal Interruption Task, Spatial Problems: Spatial Interruption Task, Verbal Problems (Anagrams): No-Interruption Task, Verbal Problems (Anagrams): Verbal Interruption Task, and Verbal Problems (Anagrams): Spatial Interruption Task. A computerized technique was developed and incorporated for data collection and material presentation. This technique was considered to have advantages over the conventional data collection format because of its ability to (1) standardize the presentation and assessment of problem solving tasks, (2) allow subjects to manipulate the problem components as they desire, simulating real world problem solving approaches, and (3) monitor the subjects’ on-going interactions through the use of intricate, covert, data collection techniques. Regression analyses were employed to analyze the data collected using this computerized technique. The findings from the present study partially support the view that problem solvers can benefit from a temporary interruption task in a problem solving sequence. The participants resolved the problems more quickly when distracted by an intervening simple cognitive task than when allowed to work continuously. It was implied that a problem solver could benefit from an interruption that involves stimuli changing visually and spatially and that also demands some degree of cognitive involvement. Although the present study did not demonstrate effects of interaction between the problem types and interruption types, the findings suggested that in the case of spatial problems, engaging in an incubation activity is likely to result in more efficient performance.

An insightful solution to a problem may be promoted by temporarily being away from the problem at hand and engaging in other tasks or problems. Wallas (1926) conceptualized such an interruption period between problem solving activities as an incubation period. The present study examines the effect of such activities that are provided as an incubation period in computer-based problem solving tasks. In addition, this study explores the potential interaction between the type of problems and the type of interruption tasks involving two types of problems (verbal and spatial) and two types of interruption activities (verbal and spatial). One hundred eighty five undergraduate volunteers participated. The participants were randomly assigned to one of the six conditions, Spatial Problems: No-Interruption Task, Spatial Problems: Verbal Interruption Task, Spatial Problems: Spatial Interruption Task, Verbal Problems (Anagrams): No-Interruption Task, Verbal Problems (Anagrams): Verbal Interruption Task, and Verbal Problems (Anagrams): Spatial Interruption Task. A computerized technique was developed and incorporated for data collection and material presentation. This technique was considered to have advantages over the conventional data collection format because of its ability to (1) standardize the presentation and assessment of problem solving tasks, (2) allow subjects to manipulate the problem components as they desire, simulating real world problem solving approaches, and (3) monitor the subjects’ on-going interactions through the use of intricate, covert, data collection techniques. Regression analyses were employed to analyze the data collected using this computerized technique. The findings from the present study partially support the view that problem solvers can benefit from a temporary interruption task in a problem solving sequence. The participants resolved the problems more quickly when distracted by an intervening simple cognitive task than when allowed to work continuously. It was implied that a problem solver could benefit from an interruption that involves stimuli changing visually and spatially and that also demands some degree of cognitive involvement. Although the present study did not demonstrate effects of interaction between the problem types and interruption types, the findings suggested that in the case of spatial problems, engaging in an incubation activity is likely to result in more efficient performance.

Graduation date: 1983

Exposure to environmental conditions that impact organ growth and function and overall performance may increase poult susceptibility to poult enteritis complex (PEC). Temperature and hypoxic stress during embryonic incubation may impact organ growth and development, development of immunocompetency, post-hatch performance and may predispose poults to enteric disease. The objective of the first study was to provide a baseline of responses to incubation conditions so that further studies could be conducted on whether these stressors may increase susceptibility to post-hatch infection. Commercial Hybrid turkey eggs were incubated at standard (37.5°C) conditions from embryonic day (ED) 0 to ED24. At ED24, eggs were divided into thirds for incubation at 37.5°C, 36.0°C, or 39.0°C from ED24 until hatch at ED28. The objective of the second study was to evaluate the effects of incubation temperature conditions on intestinal development and susceptibility to challenge with turkey coronavirus (TCV). Commercial Hybrid eggs were incubated at standard (37.5°C) conditions from ED0 to ED24. At ED24, one-third continued incubation at 37.5°C, one-third were incubated at 36.0°C, and one-third were incubated at 39.0°C from ED24 until hatch at ED28. At d 5 (0 days postinfection, dpi) half of the poults were administered 0.1mL of TCV inoculum (3 x 103 EID50/0.1 mL). The third study examined the effects of incubation temperature conditions on intestinal development and susceptibility to dual challenge with both TCV and enteropathogenic E. coli. Commercial Hybrid eggs were incubated at standard (37.5°C) incubation conditions from ED0 to ED25. At ED25, eggs were randomized and half continued incubation at 37.5°C and half were incubated at 36.0°C from ED25 until hatch at ED28. At d 5 (0 dpi) half of the poults were administered 0.1 mL of TCV inoculum (4 x 103 EID50/0.1 mL) and 0.1 mL of E. coli (2.4 x 108 CFU/mL) by oral gavage. Main effects (P≤0.05) of incubation temperature and challenge, as well as twoway interactions (P≤0.05) of temperature and challenge were observed for the parameters evaluated in each study. These studies suggest an influence of incubation temperature conditions or PEC-associated pathogens on intestinal development and early post-hatch turkey poult performance. / Ph. D.

Orientador: Nelson Luis Cappelli / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-13T05:24:07Z (GMT). No. of bitstreams: 1 AlvaradoMora_Leonardo_M.pdf: 7314728 bytes, checksum: da3e081b1a33326f3ba964a8ccdd55ac (MD5) Previous issue date: 2008 / Resumo: O aumento na demanda da produção de avicultura de corte no Brasil faz que seja necessário o desenvolvimento de novas tecnologias que melhorem a operacionalidade das máquinas incubadoras. Na atualidade existem problemas no controle de variáveis físicas no espaço confinado das incubadoras que impedem maximizar a eclosão dos ovos e afetam o desempenho do pintainho pós-eclosão. Dois destas variáveis que são tema de estudo neste trabalho são a temperatura do embrião e a perda de massa do ovo, as quais são determinantes em todo o processo pois afetam as taxas de bicagem interna e de nascimentos com sucesso. Não existem dispositivos que quantifiquem estes fatores, causando o seu desconhecimento dentro das incubadoras. Neste trabalho foi desenvolvido um sistema de medição de temperatura por sensores com contato, comparando o seu funcionamento com um sensor sem contato (Infravermelho), utilizado em medições preliminares dentro das máquinas. Foi também desenvolvido um sistema de medição de peso para quantificar a perda de massa do ovo. Para a medição da temperatura com contato foi desenvolvido um dispositivo com cinco sensores tipo circuito integrado previamente calibrados, dos quais, três foram dispostos em contato com a casca do ovo, e dois foram posicionados a 10mm da casca para medir a temperatura ambiente. Como temperatura de referência foi assumida a registrada dentro de um ovo instrumentado com três sensores tipo circuito integrado. Com o fim de simular o ambiente interno da incubadora, o ovo instrumentado, o sensor com contato e o sensor sem contato foram posicionados em um duto de ar construído em madeira de média densidade (MDF). Neste local, foram simuladas duas condições do processo de incubação: no inicio quando é preciso fornecer calor por parte da máquina para aquecer o ovo e no final quando devido à máxima produção de calor do embrião, a máquina resfria o ovo; verificando-se nas duas situações a exatidão e a influência da velocidade do ar nas leituras de temperatura dos sensores. Para a medição da massa foram usados quatro sensores de força extensométricos fixados a uma subestrutura de uma prateleira que faz parte de uma máquina de incubação de estágio único. Realizou-se a calibração estática na capacidade nominal e na faixa de utilização do sistema, com cargas de ovos colocados em duas bandejas de incubação com a finalidade de obter as principais características estáticas e a equação de calibração. Verificou-se também a influência da viragem dos ovos nas leituras da massa. O dispositivo de medição de temperatura com contato registrou maior exatidão nas leituras das duas condições simuladas. A menor exatidão deste dispositivo apresentou-se no resfriamento do ovo, chegando próximo de 96% do valor de referência; sendo esta diminuição conseqüência direta da alteração da temperatura ambiente. A velocidade do ar não influenciou nas leituras de nenhum dos sistemas de medição de temperatura. O sensor sem contato devido ao menor tempo de resposta, registrou leituras menos exatas. Em condições de regime permanente o sensor sem contato registra 3ºC de erro respeito ao valor de referência. Na calibração do sistema de pesagem na capacidade nominal e na faixa útil, registraram-se baixos valores de histerese, não linearidade e repetitividade. O erro da diferença entre a massa de referência e a massa calculada diminuiu na faixa de utilização. A influência da viragem dos ovos foi desprezível e não interferiu na precisão das leituras do valor da massa. / Abstract: The increasing demand of the poultry farming production in Brazil requires the development of new technologies that improve the results of the incubator machines. At the present time, there are some problems in the control of physical variables of the confined space of the incubators that don't allow to maximize the hatching eggs and that affect the chick performance in farm. Two of these variables; subject of study in this work, are the temperature of the embryo and the loss of mass of the egg, which are determinant through all the process because they affect the pipping measures and the number of successful births. Unfortunately till now it does not exist an adequate device that quantifies these factors, causing ignorance about it. In this work, a temperature measurement system by sensors with contact was developed, comparing its performance with a sensor without contact (Infrared), which was used in preliminary measurements inside the incubators. It was also developed a weight measurement system to quantify the loss of mass of the egg. In order to apply the measurement of temperature with contact, it was developed a device with five integrated circuit type sensors previously calibrated, three of them were in contact with the eggshell, and two of them were placed to 10mm from the eggshell to measure the air temperature around the egg. As temperature of reference it was assumed the registered one inside an instrumented egg was manufactured with three integrated circuit type sensors. In order to simulate the internal atmosphere of the incubator, the instrumented egg, the sensor with contact and the sensor without contact were placed in a tunnel of air built in wood of medium density. In this place, two conditions of the incubation process were simulated: at the beginning when it is necessary that the machine supplies heat to heat up the egg and finally when the machine cool the egg due to the maximum production of heat of the embryo; being verified in the two situations the accuracy and the influence of the air speed in the sensors temperature recordings. For the measurement of the mass, four load cells were used; they were fit and set to a shelf substructure which belong to a part of a single-stage incubation machine. The static calibration of the system was made in the nominal capacity and the rank of use, with egg placed in two incubation trays with the purpose of obtaining the main static characteristics and the calibration equation. The influence of the eggs turning in the recordings of the mass was also verified. The device of temperature measurement with contact registered a highest accuracy in the recordings of the two simulated conditions. The smallest accuracy of this device appeared or was presented during the cooling of the egg, almost achieving a 96% from the reference value, being this decrease a direct consequence of the air temperature alteration. The air speed did not influence in the recordings of any of the temperature measurement systems. The sensor without contact registered less accuracy recordings, due to its smallest delay time. In conditions of equilibrium the sensor without contact registers 3°C of error in relation to the reference value. In the calibration of the weight system in the nominal capacity and the interval of use, low values of hysteresis were registered, there were nonlinearity and repeatability. The error of the dissimilarity between the mass of reference and the calculated mass diminished in the interval of use. The influence of the eggs turning was trivial and it did not interfere in the precision of the readings of the value of the mass. / Mestrado / Maquinas Agricolas / Mestre em Engenharia Agrícola