Modelling primary proteolysis in cheddar cheese in commercial cool stores : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Bioprocess Engineering at Massey University

One issue identified as a possible problem during the manufacture of cheddar cheese is the possibility of producing a non-uniform product. It was proposed that a pallet of cheese experiencing different time-temperature histories, depending on the position within the pallet, could cause the heterogeneity. This work involved the investigation of that issue. The level of primary proteolysis observed in cheese was measured over time in cheeses of different compositions, stored at different temperatures. The remaining intact α s ₁casein was measured using reverse phase high performance liquid chromatography. Several trends were observed during maturation. High temperatures caused a faster rate of disappearance of α s ₁casein. The temperature relationship followed Arrhenius law. High moisture content caused a faster rate of the disappearance of α s ₁casein. The level of rennet added to the milk during production had a directly proportional effect on the rate of the disappearance of α s ₁casein. Salt had no observable effect in the range investigated here. From the data a kinetic model was developed that described the rate of disappearance of α s ₁casein in terms of the temperature, the moisture content, and the level of rennet in the cheese. The heat transfer occurring in the commercial pallet of cheese was mathematically modelled and solved numerically. The heat transfer model was then applied to produce data describing the time-temperature profile throughout a pallet of cheese for a variety of possible industrial storage conditions. The kinetic model developed was then used to predict the extent of proteolysis in each case. It was found that there would be significantly different levels of proteolysis within a pallet of cheese that had undergone chilling. A 10% difference in the level of proteolysis between the surface and the centre was observed after chilling for 40 days. During freezing the difference in the level of proteolysis after freezing was complete ranged from 10-25%. It was found that the heterogeneity was reduced during the thawing process and that the greatest reduction in non-uniformity was observed when thawed at lower temperatures

The Analytical Returns to Measuring a Detailed Household Roster

Households are dynamic while most surveys only collect information on individuals who are present at a single point in time. We exploit a unique and thorough household membership enumeration in Burkina Faso to consider the analytical costs of the typical static household roster. We document that households are extremely fluid with 10 percent of individuals spending sometime away over a three year period, averaging 16 of the 36 months away. The residency status of persons age 16 to 24 is most in flux. A more complete enumeration offers substantial analytical richness that is especially important for the analysis of issues that are intertwined with who is present in the household, such as the measurement of income inequality and the nature of sibling interactions in education decisions. We find that evidence of sibling rivalry in Burkina Faso appears to owe to the correlation between the presence of sisters in a household and nonagricultural income. We argue for more detailed and thorough measurement of household composition in future multi-purpose household surveys.sibling rivalry, Lorenz curves, household composition, schooling

Proteolytic depilation of lambskins : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of philosophy in Bioprocess Engineering at Massey University, Palmerston North, New Zealand

The processing of lambskins plays an important role in the New Zealand meat industry. The use of enzyme dewooling offers considerable advantages over the conventional depilation method which generates unpleasant working conditions and poses product quality risks when not properly handled. Prior to this work it was unclear from the literature why the practice of enzymatic depilation had not generally been adopted by industry. The aim of this work was to determine the problems associated with enzymatic depilation and provide a mechanistic understanding of the dewooling and damaging processes of enzyme depilation to provide underpinning knowledge for the design of a successful enzymatic depilation system. It was found that variability in depilation between different regions of the skin resulted in either over exposure of the skin to the enzyme regent and subsequent damage or underexposure of the skin to the enzyme reagent and incomplete depilation. Two approaches were taken in the work: Firstly an attempt was made for the first time to understand the variability in enzymatic depilation so that the variability observed in enzymatic depilation could potentially be reduced, thereby allowing a complete depilation process with no overexposure. Secondly an investigation was made for the first time to understand the cause of damage to skins during the process of enzymatic depilation so that the enzyme depilation process could potentially be modified to avoid damage. Experimental work characterising the time course of depilation and damage development was carried out and compared with the variation of physical properties across the skin. Correlations between depilation and physical properties such as thickness, grease content and follicle density were found. Reduction in the variability of these properties would likely improve the evenness of depilation but would not reduce it enough to eliminate damage due to over exposure. A range of techniques including: immunohistology, 2-dimensional electrophoresis, matrix assisted laser desorption ionisation, and atomic force microscopy were used to probe the structural and biochemical mechanism of enzyme depilation and damage. In this way it was found that the removal of minor collagen components were the likely cause of damage observed. In particular the removal of collagen VI was associated with a disruption of the smooth mesh of fine collagen fibres observed at the surface of the leather. The key requirement identified for a successful enzyme depilation system was the use of a broad spectrum protease which has no activity against collagen VI. The means to select a protease with these attributes was also developed by adopting a micro depilation assay incorporating immunohistology. This knowledge will enable the future development of non damaging enzyme depilatory reagents that could revolutionise the industry

1/N_c Corrections in Meson-Baryon Scattering

Corrections to meson/ground-state baryon scattering amplitudes in the 1/N_c expansion of QCD have previously been shown to be controlled by the t-channel difference |I_t - J_t| of isospin and angular momentum and by the change of hypercharge Y_t. Here we derive the corresponding expressions in the original scattering s channel, allowing for nonzero meson spin and nontrivial SU(3) flavor quantum numbers, and provide explicit examples of the crossing relevant for pi N --> rho N and K N scattering.Comment: Addition of a physical example, minor changes to clarify certain issues and add one reference. 18 pages, no figure

Residential Rivalry and Constraints on the Availability of Child Labor

We consider the influence of household-based production on human capital investment. In data from rural Burkina Faso, we document a positive correlation between the presence of girls and enrollment that disappears in households that are able to send out or receive in children. We argue that the connection between education and the sex composition of co-resident children in households that are constrained in their ability to adjust child labor owes to residential rivalry, the idea that having a greater share of resident children with an advantage in household based production increases education by reducing the within-household equilibrium value of child time.

SU(3) Clebsch-Gordan Coefficients for Baryon-Meson Coupling at Arbitrary N_c

We present explicit formulae for the SU(3) Clebsch-Gordan coefficients that are relevant for the couplings of large N_c baryons to mesons. In particular, we compute the Clebsch-Gordan series for the coupling of the octet (associated with mesons, and remains the correct representation at large N_c) to the large N_c analogs of the baryon octet and decuplet representations.Comment: 8 pages, no figures, ReVTe

Applying robotics to HAZMAT

The use of robotics in situations involving hazardous materials can significantly reduce the risk of human injuries. The Emergency Response Robotics Project, which began in October 1990 at the Jet Propulsion Laboratory, is developing a teleoperated mobile robot allowing HAZMAT (hazardous materials) teams to remotely respond to incidents involving hazardous materials. The current robot, called HAZBOT III, can assist in locating characterizing, identifying, and mitigating hazardous material incidents without risking entry team personnel. The active involvement of the JPL Fire Department HAZMAT team has been vital in developing a robotic system which enables them to perform remote reconnaissance of a HAZMAT incident site. This paper provides a brief review of the history of the project, discusses the current system in detail, and presents other areas in which robotics can be applied removing people from hazardous environments/operations

Pion Photoproduction Amplitude Relations in the 1/N_c Expansion

We derive expressions for pion photoproduction amplitudes in the 1/N_c expansion of QCD, and obtain linear relations directly from this expansion that relate electromagnetic multipole amplitudes at all energies. The leading-order relations in 1/N_c compare favorably with available data, while the next-to-leading order relations seem to provide only a small improvement. However, when resonance parameters are compared directly, the agreement at O(1/N_c) or O(1/N_c^2) is impressive.Comment: 19 pages, ReVTeX, 50 eps files combine into 5 compound figure

Pion-Nucleon Scattering Relations at Next-to-Leading Order in 1/N_c

We obtain relations between partial-wave amplitudes for pi-N-->pi-N and pi-N-->pi-Delta directly from large N_c QCD. While linear relations among certain amplitudes holding at leading order (LO) in 1/N_c were derived in the context of chiral soliton models two decades ago, the present work employs a fully model-independent framework based on consistency with the large N_c expansion. At LO we reproduce the soliton model results; however, this method allows for systematic corrections. At next-to-leading order (NLO), most relations require additional unknown functions beyond those appearing at leading order (LO) and thus have little additional predictive power. However, three NLO relations for the pi-N-->pi-Delta reaction are independent of unknown functions and make predictions accurate at this order. The amplitudes relevant to two of these relations were previously extracted from experiment. These relations describe experiment dramatically better than their LO counterparts.Comment: 8 pages, 2 figures; references adde

Digital storytelling, image-making and self-representation: Building digital literacy as an ethical response for supporting Aboriginal young peoples’ digital identities

From the early 19th century, Aboriginal culture in southeast Australia was severely disrupted by colonisation, the affects of which continue to reverberate within that community today. Visual material from the colonial period was often used as a means for classifying and labelling Aboriginal people in the southeast, resulting in many images being used to justify the idea of the so-called inevitable decline of Aboriginal people and to reinforce racist stereotypes. In this paper we discuss a digital storytelling workshop with Aboriginal young people from southeast Australia, which sought to develop digital literacy as an ethical imperative that would allow Aboriginal youth to construct visual content that not only challenged the traditional concept of digital storytelling as a linear, first-person, autobiographical narrative, but focused on developing Aboriginal young peoples’ capacity to control digital self-representations, which supported their explorations of their identity and culture. This was considered in terms of an ethical response to the use of visual methods in research with Aboriginal young people, as some images that are produced and consumed in the digital realm may provoke inappropriate and racist responses, a reality among Aboriginal communities, and one potentially aggravated by the rapid transmission of digital images via social network sites