Studies on Age-Related Changes in Equine Cheek Teeth Angulation and Dental Drift

BACKGROUND: Cheek teeth (second through fourth premolars and first through third molars) diastema is a common and painful equine disorder caused by the absence of effective tight interdental contact between these teeth. Limited objective information is available on the angulation of equine cheek teeth that control dental drift or on mesial or distal equine cheek teeth drift that should normally prevent this disorder. OBJECTIVES: To measure the angulation of the mesial and distal cheek teeth in horses of different ages, quantify age-related cheek teeth mesial and distal dental drift, and measure the cheek teeth row length in horses of different ages. STUDY DESIGN: Retrospective review of computed tomographic images of equine heads. METHODS: Case details and CT images from clinical equine cases that had undergone standing CT head examination were collated. Three sets of measurements were acquired from each head. “Head size” calculated as the distance between the caudal aspect of the orbit and the caudal aspect of the naso-incisive notch was used to standardize measurements in different sized heads. The length of the cheek teeth rows measured from the mesial aspect of the Triadan 06 occlusal surface to the distal aspect of the Triadan 11 occlusal surface. The rostro-caudal (antero-posterior) position and angulation of the mandibular and maxillary Triadan 06 and 11 teeth were measured in relation to reference lines drawn on CT images. RESULTS: Significant mesial drift occurred in the maxillary and mandibular Triadan 11s. Despite their distal angulation, the upper and lower Triadan 06s also drifted mesially. The mean angulation of Triadan 06 and 11 mandibular teeth (17.8 and 26.2°, respectively) was almost double that of maxillary teeth (9.2 and 13.3°, respectively) with both Triadan 11s having greater angulation than the 06s. Cheek teeth angulation only significantly decreased in the mandibular 06s. Cheek teeth arcade lengths decreased with age, but these decreases were not significant. MAIN LIMITATIONS: Limitations include the relatively small sample size. CONCLUSIONS: In the population of horses used for this study, age related mesial drift occurred in both Triadan 06 and 11s, and the angulation of these teeth did not decrease with age in most arcades

Measuring crack initiation and the plastic deformation behaviour of titanium aluminides under compressive and tensile uniaxial loading

At temperatures of the order of 700 °C, suitable for the operation of low and intermediate pressure turbines and compressors in gas turbine engines, gamma titanium aluminides possess a higher specific strength than nickel superalloys. However, γ-TiAl suffers from a sufficiently reduced plasticity for a threshold approach to fatigue lifing to be necessary. Improving the fatigue behaviour of γ-TiAl requires an understanding of crack nucleation and how this is related to the detailed microstructure. Towards this, the monotonic compressive and tensile deformation behaviour of this two-phase lamellar composite alloy, Ti-45Al-2Nb-2Mn(at.%)-0.8vol%TiB2, currently undergoing engine tests by Rolls Royce, has therefore been measured at both room temperature and at 700°C. Both colony and lamellar-scale deformation features of the material have been investigated. Microstructural conditions with varying lamellar thicknesses were characterised by scanning electron microscopy and transmission Kikuchi diffraction. The near-surface plastic strain field and the build-up of local strains have been measured, using digital image correlation, with a remodelled gold speckle pattern, and compared with misorientation mapping using electron backscatter diffraction, both before and after testing. Temperature was found to have a significant impact on the active deformation mechanisms and their directions relative to the lamellae; this affects the ability of the material to provide compatible deformation. At high temperature, the shear generated upon twinning was found to be closely associated to debonding at colony boundaries. This is related to the possible accumulation of damage in cyclic loading

Four-lepton production at hadron colliders: aMC@NLO predictions with theoretical uncertainties

We use aMC@NLO to study the production of four charged leptons at the LHC, performing parton showers with both HERWIG and Pythia6. Our underlying matrix element calculation features the full next-to-leading order $O(\alpha_S)$ result and the $O(\alpha_S^2)$ contribution of the $gg$ channel, and it includes all off-shell, spin-correlation, virtual-photon-exchange, and interference effects. We present several key distributions together with the corresponding theoretical uncertainties. These are obtained through a process-independent technique that allows aMC@NLO to compute scale and PDF uncertainties in a fully automated way and at no extra CPU-time costComment: 24 pages, 6 figure

Transitioning Primary School Students with Autism Spectrum Disorder from a Special Education Setting to a Mainstream Classroom: Successes and Difficulties

Students with Autism Spectrum Disorders (ASD) are increasingly being educated in mainstream classroom environments. Commonly students commence their education in a segregated setting, transitioning to mainstream education after a process of skills development. For each student, transition is a unique and complex process. In NSW Australia, Autism Spectrum Australia (Aspect) offers a satellite classroom program, in which students are placed in a segregated classroom within a mainstream school, and offered specialised education with the goal of future transition. This article examines the successes and difficulties experienced by three primary school students who transitioned from an Aspect satellite classroom to a mainstream classroom environment during primary school. Utilising Rogoff’s sociocultural framework, it analyses the transition process from the perspective of personal, interpersonal and institutional contexts. Results identified several factors that facilitated successful transition, including careful pre-transition preparation, adequate cross-institutional communication, and the adoption of appropriate in-classroom strategies. Despite the overall success of each transition, students encountered significant difficulties. These included social difficulties in the playground, and academic challenges. This research adds to the scarce research literature on factors influencing transition

NETWORKED2‐Subfamily Proteins Regulate the Cortical Actin Cytoskeleton of Growing Pollen Tubes and Polarised Pollen Tube Growth

We have recently characterised NET2A as a pollen‐specific actin‐binding protein which binds F‐actin at the plasma membrane of growing pollen tubes. However, the role of NET2 proteins in pollen development and fertilisation have yet to be elucidated. To further characterise the role of Arabidopsis NET2 proteins in pollen development and fertilisation, we analysed the subcellular localisation of NET2A over the course of pollen grain development, and investigated the role of the NET2 family using net2 loss‐of‐function mutants. We observed NET2A to localise to the F‐actin cytoskeleton in developing pollen grains as it underwent striking structural reorganisations at specific stages of development and during germination, and pollen tube growth. Furthermore, net2 loss‐of‐function mutants exhibited striking morphological defects in the early stages of pollen tube growth, arising from frequent alterations to pollen tube growth trajectory. We observed defects in the cortical actin cytoskeleton and actin‐driven subcellular processes in net2 mutant pollen tubes. We demonstrate that NET2 proteins are essential for normal actin‐driven pollen development highlighting an important role for the NET2 family members in regulating pollen tube growth during fertilisation

Quantum Fields in a Big Crunch/Big Bang Spacetime

We consider quantum field theory on a spacetime representing the Big Crunch/Big Bang transition postulated in the ekpyrotic or cyclic cosmologies. We show via several independent methods that an essentially unique matching rule holds connecting the incoming state, in which a single extra dimension shrinks to zero, to the outgoing state in which it re-expands at the same rate. For free fields in our construction there is no particle production from the incoming adiabatic vacuum. When interactions are included the total particle production for fixed external momentum is finite at tree level. We discuss a formal correspondence between our construction and quantum field theory on de Sitter spacetime.Comment: 30 pages, RevTex file, five postscript figure file

Vector Boson Pair Production in Hadronic Collisions at Order αs\alpha_s: Lepton Correlations and Anomalous Couplings

We present cross sections for production of electroweak vector boson pairs, $WW$, $WZ$ and $ZZ$, in $p\bar{p}$ and $pp$ collisions, at next-to-leading order in $\alpha_s$. We treat the leptonic decays of the bosons in the narrow-width approximation, but retain all spin information via decay angle correlations. We also include the effects of $WWZ$ and $WW\gamma$ anomalous couplings.Comment: 23 pages, 8 figures, 3 table

Direct observation of molecular cooperativity near the glass transition

We describe direct observations of molecular cooperativity near the glass transition in poly-vinyl-acetate (PVAc), through nanometer-scale probing of dielectric fluctuations. Molecular clusters switched spontaneously between two to four distinct configurations, producing complex random-telegraph-signals (RTS). Analysis of the RTS and their power spectra shows that individual clusters exhibit both transient dynamical heterogeneity and non-exponential kinetics.Comment: 14 pages pdf, need Acrobat Reade