A unified approach to the gauging of space-time and internal symmetries

The properties of the manifold of a Lie groupG, fibered by the cosets of a sub-groupH, are exploited to obtain a geometrical description of gauge theories in space-timeG/H. Gauge potentials and matter fields are pullbacks of equivariant fields onG. Our concept of a connection is more restricted than that in the similar scheme of Ne'eman and Regge, so that its degrees of freedom are just those of a set of gauge potentials forG, onG/H, with no redundant components. The ldquotranslationalrdquo gauge potentials give rise in a natural way to a nonsingular tetrad onG/H. The underlying groupG to be gauged is the groupG of left translations on the manifoldG and is associated with a ldquotrivialrdquo connection, namely the Maurer-Cartan form. Gauge transformations are all those diffeomorphisms onG that preserve the fiber-bundle structure.

Assessment of quality defects in macadamia kernels using NIR spectroscopy

Spectral data were collected of intact and ground kernels using 3 instruments (using Si-PbS, Si, and InGaAs detectors), operating over different areas of the spectrum (between 400 and 2500 nm) and employing transmittance, interactance, and reflectance sample presentation strategies. Kernels were assessed on the basis of oil and water content, and with respect to the defect categories of insect damage, rancidity, discoloration, mould growth, germination, and decomposition. Predictive model performance statistics for oil content models were acceptable on all instruments (R2 > 0.98; RMSECV < 2.5%, which is similar to reference analysis error), although that for the instrument employing reflectance optics was inferior to models developed for the instruments employing transmission optics. The spectral positions for calibration coefficients were consistent with absorbance due to the third overtones of CH2 stretching. Calibration models for moisture content in ground samples were acceptable on all instruments (R2 > 0.97; RMSECV < 0.2%), whereas calibration models for intact kernels were relatively poor. Calibration coefficients were more highly weighted around 1360, 740 and 840 nm, consistent with absorbance due to overtones of O-H stretching and combination. Intact kernels with brown centres or rancidity could be discriminated from each other and from sound kernels using principal component analysis. Part kernels affected by insect damage, discoloration, mould growth, germination, and decomposition could be discriminated from sound kernels. However, discrimination among these defect categories was not distinct and could not be validated on an independent set. It is concluded that there is good potential for a low cost Si photodiode array instrument to be employed to identify some quality defects of intact macadamia kernels and to quantify oil and moisture content of kernels in the process laboratory and for oil content in-line. Further work is required to examine the robustness of predictive models across different populations, including growing districts, cultivars and times of harvest.

Assessment of internal quality attributes of mandarin fruit. 1. NIR calibration model development

The utility of near infrared spectroscopy as a non-invasive technique for the assessment of internal eating quality parameters of mandarin fruit (Citrus reticulata cv. Imperial) was assessed. The calibration procedure for the attributes of TSS (total soluble solids) and DM (dry matter) was optimised with respect to a reference sampling technique, scan averaging, spectral window, data pre-treatment (in terms of derivative treatment and scatter correction routine) and regression procedure. The recommended procedure involved sampling of an equatorial position on the fruit with 1 scan per spectrum, and modified partial least squares model development on a 720–950-nm window, pre-treated as first derivative absorbance data (gap size of 4 data points) with standard normal variance and detrend scatter correction. Calibration model performance for the attributes of TSS and DM content was encouraging (typical Rc2 of >0.75 and 0.90, respectively; typical root mean squared standard error of calibration of <0.4 and 0.6%, respectively), whereas that for juiciness and total acidity was unacceptable. The robustness of the TSS and DM calibrations across new populations of fruit is documented in a companion study.

Assessment of internal quality attributes of mandarin fruit. 2. NIR calibration model robustness

The robustness of multivariate calibration models, based on near infrared spectroscopy, for the assessment of total soluble solids (TSS) and dry matter (DM) of intact mandarin fruit (Citrus reticulata cv. Imperial) was assessed. TSS calibration model performance was validated in terms of prediction of populations of fruit not in the original population (different harvest days from a single tree, different harvest localities, different harvest seasons). Of these, calibration performance was most affected by validation across seasons (signal to noise statistic on root mean squared error of prediction of 3.8, compared with 20 and 13 for locality and harvest day, respectively). Procedures for sample selection from the validation population for addition to the calibration population (‘model updating’) were considered for both TSS and DM models. Random selection from the validation group worked as well as more sophisticated selection procedures, with approximately 20 samples required. Models that were developed using samples at a range of temperatures were robust in validation for TSS and DM.

Large cryptic internal sequence repeats in protein structures from Homo sapiens

Amino acid sequences are known to constantly mutate and diverge unless there is a limiting condition that makes such a change deleterious. However, closer examination of the sequence and structure reveals that a few large, cryptic repeats are nevertheless sequentially conserved. This leads to the question of why only certain repeats are conserved at the sequence level. It would be interesting to find out if these sequences maintain their conservation at the three-dimensional structure level. They can play an active role in protein and nucleotide stability, thus not only ensring proper functioning but also potentiating malfunction and disease. Therefore, insights into any aspect of the repeats - be it structure, function or evolution - would prove to be of some importance. This study aims to address the relationship between protein sequence and its three-dimensional structure, by examining if large cryptic sequence repeats have the same structure.

A digital imaging technique to quantify the incidence of internal browning in potato (Solanum tuberosum) tubers

Internal browning disorders, including brown fleck (BF), in potato (Solanum tuberosum) tubers greatly reduce tuber quality, but the causes are not well understood. This is due, in part, to the highly variable data provided by visual value-based rating systems. A digital imaging technique was developed to quantify accurately the incidence of internal browning in potato tubers. Images of tuber sections were scanned using a flatbed scanner and digitally enhanced to highlight tuber BF lesions, and the area of affected tissue calculated using pixel quantification software. Digital imaging allowed for the determination of previously unused indices of the incidence and severity of internal browning in potato tubers. Statistical analysis of the comparison between digitally derived and visual-rating BF data from a glasshouse experiment showed that digital data greatly improved the delineation of treatment effects. The F-test probability was further improved through square root or logarithmic data transformations of the digital data, but not of the visual-rating data. Data from a field experiment showed that the area of tuber affected by BF and the number of small BF lesions increased with time and with increase in tuber size. The results from this study indicate that digital imaging of internal browning disorders of potato tubers holds much promise in determining their causes that heretofore have proved elusive.

Effects Of 5' Flanking Sequences And Changes In The 5' Internal Control Region On The Transcription Of Rice Transfer-Rna Gcc Cly Gene

A stretch of 71 nucleotides in a 1.2 kilobase pair Pst I fragment of rice DNA was identified as tRNA~ gene by hybridization and nucleotide sequence analyses. The hybridization of genomic DNA with the tRNA gene showed that there are about 10 glycine tRNA genes per diploid rice genome. The 3' and 5' internal control regions, where RNA polymerase III and transcription factors bind, were found to be present in the coding sequence. The gene was transcribed into a 4S product in an yeast cell-free extract. The substitution of 5' internal control region with analogous sequences from either M13mpl9 or M13mpl8 DNA did not affect the transcription of the gene in vitro. The changes in three highly conserved nucleotides in the consensus 5' internal control region (RGYNNARYGG; R = purine, Y = pyrimidine, N = any nucleotide) did not affect transcription showing that these nucleotides are not essential for promotion of transcription. There were two 16 base pair repeats, 'TGTTTGTTTCAGCTTA' at - 130 and - 375 positions upstream from the start of the gene. Deletion of 5' flanking sequences including the 16 base pair repeat at - 375 showed increased transcription indicating that these sequences negatively modulate the expression of the gene.

Rapid internal drainage rates in Ferrosols

Adoption of conservation tillage practices on Red Ferrosol soils in the inland Burnett area of south-east Queensland has been shown to reduce runoff and subsequent soil erosion. However, improved infiltration resulting from these measures has not improved crop performance and there are suggestions of increased loss of soil water via deep drainage. This paper reports data monitoring soil water under real and artificial rainfall events in commercial fields and long-term tillage experiments, and uses the data to explore the rate and mechanisms of deep drainage in this soil type. Soils were characterised by large drainable porosities (≥0.10 m3/m3) in all parts of the profile to depths of 1.50 m, with drainable porosity similar to available water content (AWC) at 0.25 and 0.75 m, but >60% higher than AWC at 1.50 m. Hydraulic conductivity immediately below the tilled layer in both continuously cropped soils and those after a ley pasture phase was shown to decline with increasing soil moisture content, although the rate of decline was much greater in continuously cropped soil. At moisture contents approaching the drained upper limit (pore water pressure = -100cm H2O), estimates of saturated hydraulic conductivity after a ley pasture were 3-5 times greater than in continuously cropped soil, suggesting much greater rates of deep drainage in the former when soils are moist. Hydraulic tensiometers and fringe capacitance sensors monitored during real and artificial rainfall events showed evidence of soils approaching saturation in the surface layers (top 0.30-0.40 m), but there was no evidence of soil moistures exceeding the drained upper limit (i.e. pore water pressures ≤ -100 cm H2O) in deeper layers. Recovery of applied soil water within the top 1.00-1.20 m of the profile during or immediately after rainfall events declined as the starting profile moisture content increased. These effects were consistent with very rapid rates of internal drainage. Sensors deeper in the profile were unable to detect this drainage due to either non-uniformity of conducting macropores (i.e. bypass flow) or unsaturated conductivities in deeper layers that far exceed the saturated hydraulic conductivity of the infiltration throttle at the bottom of the cultivated layer. Large increases in unsaturated hydraulic conductivities are likely with only small increases in water content above the drained upper limit. Further studies with drainage lysimeters and large banks of hydraulic tensiometers are planned to quantify drainage risk in these soil types.

Effect of density discontinuity on Alfvén internal gravity waves

The stability characteristics of Alfvén Internal gravity waves for an inviscid, nondissipative, Boussinesq fluid undergoing shear in the presence of a density discontinuity with and without a rigid boundary is studied.

Internal nitride formation during gas-phase thermal nitridation of titanium

Titanium nitride surface layers were prepared by gas-phase thermal nitridation of pure titanium in an ammonia atmosphere at 1373 K for different times. In addition to the surface nitride layer, nitride/hydride formation was observed in the bulk of the specimen. The cross-section of the specimen was characterized by various techniques such as optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, secondary ion mass spectrometry and nanomechanical testing, and the mechanism of formation of these phases is discussed.

Resin defect impacts on the value of graded recovery and evaluation of technologies for internal defect detection in slash pine logs.

The key outcome will be to identify a technology that is practical to use to scan logs identified by the modelling as suspect or marginal for sawing and to confirm their unsuitability for value adding sawing by internal scanning.

Mitochondrial Malfunction in Tumor Formation and Neuromuscular Diseases : Consequences of defects in fumarate hydratase and in the respiratory chain

The mitochondrion is an organelle of outmost importance, and the mitochondrial network performs an array of functions that go well beyond ATP synthesis. Defects in mitochondrial performance lead to diseases, often affecting nervous system and muscle. Although many of these mitochondrial diseases have been linked to defects in specific genes, the molecular mechanisms underlying the pathologies remain unclear. The work in this thesis aims to determine how defects in mitochondria are communicated within - and interpreted by - the cells, and how this contributes to disease phenotypes. Fumarate hydratase (FH) is an enzyme of the citrate cycle. Recessive defects in FH lead to infantile mitochondrial encephalopathies, while dominant mutations predispose to tumor formation. Defects in succinate dehydrogenase (SDH), the enzyme that precedes FH in the citrate cycle, have also been described. Mutations in SDH subunits SDHB, SDHC and SDHD are associated with tumor predisposition, while mutations in SDHA lead to a characteristic mitochondrial encephalopathy of childhood. Thus, the citrate cycle, via FH and SDH, seems to have essential roles in mitochondrial function, as well as in the regulation of processes such as cell proliferation, differentiation or death. Tumor predisposition is not a typical feature of mitochondrial energy deficiency diseases. However, defects in citrate cycle enzymes also affect mitochondrial energy metabolism. It is therefore necessary to distinguish what is specific for defects in citrate cycle, and thus possibly associated with the tumor phenotype, from the generic consequences of defects in mitochondrial aerobic metabolism. We used primary fibroblasts from patients with recessive FH defects to study the cellular consequences of FH-deficiency (FH-). Similarly to the tumors observed in FH- patients, these fibroblasts have very low FH activity. The use of primary cells has the advantage that they are diploid, in contrast with the aneuploid tumor cells, thereby enabling the study of the early consequences of FH- in diploid background, before tumorigenesis and aneuploidy. To distinguish the specific consequences of FH- from typical consequences of defects in mitochondrial aerobic metabolism, we used primary fibroblasts from patients with MELAS (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) and from patients with NARP (neuropathy, ataxia and retinitis pigmentosa). These diseases also affect mitochondrial aerobic metabolism but are not known to predispose to tumor formation. To study in vivo the systemic consequences of defects in mitochondrial aerobic metabolism, we used a transgenic mouse model of late-onset mitochondrial myopathy. The mouse contains a transgene with an in-frame duplication of a segment of Twinkle, the mitochondrial replicative helicase, whose defects underlie the human disease progressive external ophthalmoplegia. This mouse model replicates the phenotype in the patients, particularly neuronal degeneration, mitochondrial myopathy, and subtle decrease of respiratory chain activity associated with mtDNA deletions. Due to the accumulation of mtDNA deletions, the mouse was named deletor. We first studied the consequences of FH- and of respiratory chain defects for energy metabolism in primary fibroblasts. To further characterize the effects of FH- and respiratory chain malfunction in primary fibroblasts at transcriptional level, we used expression microarrays. In order to understand the in vivo consequences of respiratory chain defects in vivo, we also studied the transcriptional consequences of Twinkle defects in deletor mice skeletal muscle, cerebellum and hippocampus. Fumarate accumulated in the FH- homozygous cells, but not in the compound heterozygous lines. However, virtually all FH- lines lacked cytoplasmic FH. Induction of glycolysis was common to FH-, MELAS and NARP fibroblasts. In deletor muscle glycolysis seemed to be upregulated. This was in contrast with deletor cerebellum and hippocampus, where mitochondrial biogenesis was in progress. Despite sharing a glycolytic pattern in energy metabolism, FH- and respiratory chain defects led to opposite consequences in redox environment. FH- was associated with reduced redox environment, while MELAS and NARP displayed evidences of oxidative stress. The deletor cerebellum had transcriptional induction of antioxidant defenses, suggesting increased production of reactive oxygen species. Since the fibroblasts do not represent the tissues where the tumors appear in FH- patients, we compared the fibroblast array data with the data from FH- leiomyomas and normal myometrium. This allowed the determination of the pathways and networks affected by FH-deficiency in primary cells that are also relevant for myoma formation. A key pathway regulating smooth muscle differentiation, SRF (serum response factor)-FOS-JUNB, was found to be downregulated in FH- cells and in myomas. While in the deletor mouse many pathways were affected in a tissue-specific basis, like FGF21 induction in the deletor muscle, others were systemic, such as the downregulation of ALAS2-linked heme synthesis in all deletor tissues analyzed. However, interestingly, even a tissue-specific response of FGF21 excretion could elicit a global starvation response. The work presented in this thesis has contributed to a better understanding of mitochondrial stress signalling and of pathways interpreting and transducing it to human pathology.

Fractional power dependence of rate on activation energy for reactions with very low internal barriers

The dynamics of reactions with low internal barriers are studied both analytically and numerically for two different models. Exact expressions for the average rate,kI, are obtained by solving the associated first passage time problems. Both the average rate constant, kI, and the numerically calculated long-time rate constant, kL, show a fractional power law dependence on the barrier height for very low barriers. The crossover of the reaction dynamics from low to high barrier is investigated.