6,014 research outputs found

    Importance of understanding variable and transient energy demand in large multi-product industrial plants for process integration

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    There have been some news releases claiming that Professor Henle in Germany has found the chemical identity of UMF, and that in future chemical analysis will be used instead of assays of antibacterial activity to indicate the level of UMF in manuka honey. Both of these claims are misleading. Because the level of active substance in manuka honey is an unreliable indication of the level of antibacterial activity and can be very misleading, it is hard to see any commercial advantage for it to be used to indicate antibacterial activity other than if someone wanted to fool the consumer into thinking that the higher numbers are giving them a level of antibacterial activity that is far higher than they are really getting

    Development and application of a clothed thermoregulatory model

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    Mathematical models of human thermoregulation can be used to assess the habitability of thermal environments prior to human exposure. Work continues to improve the performance of these models to reduce concerns surrounding the accuracy of their predictions. The aims of this thesis were to develop an existing thermoregulatory model (LUT25-node model). The developments made to the LUT25-node model, now enable it to predict the thermal responses of heat acclimated subjects of differing size, while its clothing model was improved to consider the addition and distribution of clothing properties. Validations of these modifications, confirmed that predictions from the model were improved. The thesis also looks at practical applications of the LUT25-node model. This included a modification to the model enabling backward modelling; predicting how the thermal stress should be altered to achieve a desired limit of thermal strain. Several hypothetical scenarios illustrated the practical applications of this modification. In addition, the LUT25-node model was used to explain the initial drop in deep body temperature at the onset of exercise. This investigation concluded that the temperature drop is due to the return of cool blood to the body core from initially cool working muscles. Finally, the poor predictions of the LUT25-node model for cold exposures was investigated. Previous investigators suspected that this was due to the limited number of thermal layers in the body segments of the model. However, predictions from a multi-layered LUT25-node model, developed with the finite volume software package PHOENICS, suggest that increasing the number of thermal layers reduces the accuracy of the model's predictions for cold exposures. In conclusion, this thesis has contributed to the continued development of a human thermoregulatory model and illustrated its practical benefits. It is recommended that future work centres on addressing additional limitations of the LUT25-node model identified in this study

    The effect of isoprenaline on induction of tumours by methyl nitrosourea in the salivary and mammary glands of female wistar rats.

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    Pretreatment of rats with isoprenaline sulphate (IPR) stimulated DNA synthesis in both salivary and mammary gland tissues. Salivary gland tumours induced by N-methyl-N-nitrosourea (MNU) were observed for the first time in rats, but occurred only in IPR-pretreated animals given MNU during the period of IPR-stimulated DNA synthesis. The cumulative index of MNU-induced mammary tumours and the number of tumours per tumour-bearing rat were increased by IPR-pretreament only if the animals received MNU during the period of IPR-stimulated DNA synthesis

    Positive regulation of meiotic DNA double-strand break formation by activation of the DNA damage checkpoint kinase Mec1(ATR)

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    During meiosis, formation and repair of programmed DNA double-strand breaks (DSBs) create genetic exchange between homologous chromosomes-a process that is critical for reductional meiotic chromosome segregation and the production of genetically diverse sexually reproducing populations. Meiotic DSB formation is a complex process, requiring numerous proteins, of which Spo11 is the evolutionarily conserved catalytic subunit. Precisely how Spo11 and its accessory proteins function or are regulated is unclear. Here, we use Saccharomyces cerevisiae to reveal that meiotic DSB formation is modulated by the Mec1(ATR) branch of the DNA damage signalling cascade, promoting DSB formation when Spo11-mediated catalysis is compromised. Activation of the positive feedback pathway correlates with the formation of single-stranded DNA (ssDNA) recombination intermediates and activation of the downstream kinase, Mek1. We show that the requirement for checkpoint activation can be rescued by prolonging meiotic prophase by deleting the NDT80 transcription factor, and that even transient prophase arrest caused by Ndt80 depletion is sufficient to restore meiotic spore viability in checkpoint mutants. Our observations are unexpected given recent reports that the complementary kinase pathway Tel1(ATM) acts to inhibit DSB formation. We propose that such antagonistic regulation of DSB formation by Mec1 and Tel1 creates a regulatory mechanism, where the absolute frequency of DSBs is maintained at a level optimal for genetic exchange and efficient chromosome segregation

    Non-continuous and variable rate processes: Optimisation for energy use

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    The need to develop new and improved ways of reducing energy use and increasing energy intensity in industrial processes is currently a major issue in New Zealand. Little attention has been given to optimisation of non-continuous processes in the past, due to their complexity, yet they remain an essential and often energy intensive component of many industrial sites. Novel models based on pinch analysis that aid in minimising utility usage have been constructed here through the adaptation of proven continuous techniques. The knowledge has been integrated into a user friendly software package, and allows the optimisation of processes under variable operating rates and batch conditions. An example problem demonstrates the improvements in energy use that can be gained when using these techniques to analyse non-continuous data. A comparison with results achieved using a pseudo-continuous method show that the method described can provide simultaneous reductions in capital and operating costs

    A derivative method for minimising total cost in heat exchanger networks through optimal area allocation

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    This paper presents a novel Cost Derivative Method (CDM) for finding the optimal area allocation for a defined Heat Exchanger Network (HEN) structure and stream data, without any stream splits to achieve minimum total cost. Using the Pinch Design Method (PDM) to determine the HEN structure, the approach attempts to add, remove and shift area to exchangers where economic benefits are returned. From the derivation of the method, it is found that the slope of the Ξ΅-NTU relationship for the specific heat exchanger type, in combination with the difference in exchanger inlet temperatures and the overall heat transfer coefficient, are critical to calculating the extra overall duty each incremental area element returns. The approach is able to account for differences in film coefficients, heat exchanger types, flow arrangements, exchanger cost functions, and utility pricing. Incorporated into the method is the newly defined β€œutility cost savings flow-on” factor, ΞΈ, which evaluates downstream effects on utility use and cost that are caused by changing the area of one exchanger. To illustrate the method, the CDM is applied to the distillation example of Gundersen (2000). After applying the new CDM, the total annual cost was reduced by 7.1 % mainly due to 24 % less HEN area for similar heat recovery. Area reduction resulted from one exchanger having a minimum approach temperature (Ξ”Tmin) of 7.7 Β°C while the other recovery exchangers had larger Ξ”Tmin values. The optimum Ξ”Tmin for the PDM was 12.5 Β°C. The CDM solution was found to give a comparable minimum total area and cost to two recently published programming HEN synthesis solutions for the same problem without requiring the increased network complexity through multiple stream splits

    AXONAL TRANSPORT AND TURNOVER OF PROLINE- AND LEUCINE-LABELED PROTEIN IN THE GOLDFISH VISUAL SYSTEM

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    The suitability of radioactively labeled proline as a marker of axonally transported protein in the goldfish visual system is further investigated and compared with another amino acid, leucine, in double-label experiments. Intraocularly injected proline is incorporated into protein in the eye S times more efficiently than is leucine, while local labeling of brain protein from precursor which has left the eye and entered the blood, (observed in the ipsilateral optic tectum) is five- to eight-fold less from proline than from leucine. The difference is attributed to the superior transport of leucine, an essential amino acid, into the brain from the blood. Once in the brain, the apparent rates of incorporation of the two amino acids are similar. Proline- or leucine-labeled, axonally transported proteins have a longer apparent half-life in the brain than do proteins labeled from intracranial injection of the precursors. By either route, proline-labeled proteins have a longer apparent half-life than leucine-labeled proteins. It is proposed that proline, released from protein breakdown is reutilized to a greater extent than is leucine.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65647/1/j.1471-4159.1974.tb10757.x.pd

    PHP15 COMPARISON OF MARKET EXCLUSIVITY OF PHARMACEUTICALS IN CANADA, THE UNITED STATES, THE UNITED KINGDOM AND FRANCE

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    A uniform analysis of HD209458b Spitzer/IRAC lightcurves with Gaussian process models

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    We present an analysis of Spitzer/IRAC primary transit and secondary eclipse lightcurves measured for HD209458b, using Gaussian process models to marginalise over the intrapixel sensitivity variations in the 3.6 micron and 4.5 micron channels and the ramp effect in the 5.8 micron and 8.0 micron channels. The main advantage of this approach is that we can account for a broad range of degeneracies between the planet signal and systematics without actually having to specify a deterministic functional form for the latter. Our results do not confirm a previous claim of water absorption in transmission. Instead, our results are more consistent with a featureless transmission spectrum, possibly due to a cloud deck obscuring molecular absorption bands. For the emission data, our values are not consistent with the thermal inversion in the dayside atmosphere that was originally inferred from these data. Instead, we agree with another re-analysis of these same data, which concluded a non-inverted atmosphere provides a better fit. We find that a solar-abundance clear-atmosphere model without a thermal inversion underpredicts the measured emission in the 4.5 micron channel, which may suggest the atmosphere is depleted in carbon monoxide. An acceptable fit to the emission data can be achieved by assuming that the planet radiates as an isothermal blackbody with a temperature of 1484Β±181484\pm 18 K.Comment: 18 pages, 5 figures, 6 tables. Accepted by MNRA
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