Noble Metals in Arc Basaltic Magmas Worldwide: A Case Study of Modern and Pre-Historic Lavas of the Tolbachik Volcano, Kamchatka

Platinum-group elements (PGE) and gold are a promising tool to assess the processes of mantle melting beneath the subduction zones. However, fractionation processes in magmas inevitably overwrite the initial metal budgets of magmas, making constraints on the melting processes inconclusive. Moreover, little is still known about the geochemical behavior of a particular metal in a single arc magmatic system, from mantle melting towards magma solidification. Here we compare noble metals in lavas from several eruptions of the Tolbachik volcano (Kamchatka arc) to better understand the effects of magma differentiation, estimate primary melt compositions and make constraints on the mantle melting. We show that Ir, Ru, Rh and, to a lesser extent, Pt are compatible during magmatic differentiation. The pronounced incompatible behavior of Cu and Pd, observed in Tolbachik magmas, rules out the significant influence of sulfide melts on the early magmatic evolution in this particular case. Gold is also incompatible during magmatic differentiation; however, its systematics can be affected by the inferred gold recycling in the plumbing system of Tolbachik. Although the Tolbachik lavas show only slightly higher PGE fractionation than in MORB, a notable negative Ru anomaly (higher Pt/Ru and Ir/Ru) is observed. We attribute this to be a result of greater oxidation in the subarc mantle (by 1–4 log units), which promotes crystallization of Ru-bearing phases such as Fe3+-rich Cr-spinel and laurite. The estimated Pd contents for the parental melt of the Tolbachik lavas approaches 6.5 ppb. This is several times higher than reported MORB values (1.5 ± 0.5 ppb), suggesting the enrichment of Pd in the mantle wedge. Our results highlight the influence of the subduction-related processes and mantle wedge refertilization on the noble metal budgets of arc magmas.

Improved methods for distribution of superelevation

The American Association of State Highway and Transportation Officials (AASHTO) provide 5 methods for distributing highway superelevation (e) and side friction (f). Method 1 (linear) is inferior to Method 5 (curvilinear). AASHTO Method 5 deals with speed variations, but its complex mathematical calculation affects design consistency. Safety margin is the difference between design and maximum limiting speed. This thesis describes distribution of superelevation (e) and side friction factor (f) based on the EAU and SAU methods using AASHTO and two different curves from the unsymmetrical curve; the equal parabolic arcs "EAU Curve" and a single arc unsymmetrical curve "SAU Curve". The thesis also describes e and f distributions based on the optimization model. The EAU and SAU methods and Parametric Cubic Optimization Model improve highway design consistency based on safety margins. Examples show the methods and optimization model are superior to AASHTO methods.

Improved methods for distribution of superelevation

The American Association of State Highway and Transportation Officials (AASHTO) provide 5 methods for distributing highway superelevation (e) and side friction (f). Method 1 (linear) is inferior to Method 5 (curvilinear). AASHTO Method 5 deals with speed variations, but its complex mathematical calculation affects design consistency. Safety margin is the difference between design and maximum limiting speed. This thesis describes distribution of superelevation (e) and side friction factor (f) based on the EAU and SAU methods using AASHTO and two different curves from the unsymmetrical curve; the equal parabolic arcs "EAU Curve" and a single arc unsymmetrical curve "SAU Curve". The thesis also describes e and f distributions based on the optimization model. The EAU and SAU methods and Parametric Cubic Optimization Model improve highway design consistency based on safety margins. Examples show the methods and optimization model are superior to AASHTO methods.

Optimal Space Trajectories with Multiple Coast Arcs Using Modified Equinoctial Elements

The detection of optimal trajectories with multiple coast arcs represents a significant and challenging problem of practical relevance in space mission analysis. Two such types of optimal paths are analyzed in this study: (a) minimum-time low-thrust trajectories with eclipse intervals and (b) minimum-fuel finite-thrust paths. Modified equinoctial elements are used to describe the orbit dynamics. Problem (a) is formulated as a multiple-arc optimization problem, and additional, specific multipoint necessary conditions for optimality are derived. These yield the jump conditions for the costate variables at the transitions from light to shadow (and vice versa). A sequential solution methodology capable of enforcing all the multipoint conditions is proposed and successfully applied in an illustrative numerical example. Unlike several preceding researches, no regularization or averaging is required to make tractable and solve the problem. Moreover, this work revisits problem (b), formulated as a single-arc optimization problem, while emphasizing the substantial analytical differences between minimum-fuel paths and problem (a). This study also proves the existence and provides the derivation of the closed-form expressions for the costate variables (associated with equinoctial elements) along optimal coast arcs.

RESISTANCE OF THICK-WALLED BARRIER IN PENETRATION OF A SOLID BODY

The authors discuss bursting of barriers by solid bodies. The resistance function changes along a single-arc sinusoid. The equation of motion of a solid body is solved. The velocity of the drift hammer to reach the back of the barrier is determined. The alternative initial velocities such that the solid body is jammed in the barrier or is shot outside the barrier are examined. Determination of the barrier resistance force versus the shoot-out velocity of the drift hammer is discussed.

Melody complexity of infants’ cry and non-cry vocalisations increases across the first six months

In early infancy, melody provides the most salient prosodic element for language acquisition and there is huge evidence for infants’ precocious aptitudes for musical and speech melody perception. Yet, a lack of knowledge remains with respect to melody patterns of infants’ vocalisations. In a search for developmental regularities of cry and non-cry vocalisations and for building blocks of prosody (intonation) over the first 6 months of life, more than 67,500 melodies (fundamental frequency contours) of 277 healthy infants from monolingual German families were quantitatively analysed. Based on objective criteria, vocalisations with well-identifiable melodies were grouped into those exhibiting a simple (single-arc) or complex (multiple-arc) melody pattern. Longitudinal analysis using fractional polynomial multi-level mixed effects logistic regression models were applied to these patterns. A significant age (but not sex) dependent developmental pattern towards more complexity was demonstrated in both vocalisation types over the observation period. The theoretical concept of melody development (MD-Model) contends that melody complexification is an important building block on the path towards language. Recognition of this developmental process will considerably improve not only our understanding of early preparatory processes for language acquisition, but most importantly also allow for the creation of clinically robust risk markers for developmental language disorders.

Optimisation of user-selectable volumetric modulated arc therapy (VMAT) planning parameters: A study of VMAT arcs for prostate and head-and-neck cancers

Objective: To evaluate different VMAT planning techniques for a multi-leaf collimator (MLC)providing maximum aperture of 21 × 16 cm². Methods: A VMAT planning study of nine prostate and nine head-and-neck cancer patients was carried out. The patients were previously treated with Intensity Modulated Radiotherapy (IMRT) technique during 2014-15, at radiation oncology SanBortolo Hospital, Vicenza, Italy. Three VMAT plans for each of prostate and head-and-neck cancer patient were optimized using Pinnacle treatment planning system for 6MV photon beam from ElektaSynergyS®Linac system. Single arc, dual arc and combined two independent-single-arcs were optimized for collimator angle 45°. VMAT treatment planning comparison was made among single-arc dual-arc and combined two independent-single-arcs. The student’s t-test (two-sided) with p ? 0.05 was applied for significant difference between dose volume indices of plans. Results: All VMAT techniques produced clinically acceptable plans for prostate, while for head-and-neck, DA and ISAs significantly improved target coverage compared to SA. Single arc is sufficient for prostate, while inefficient in case of head-and-neck dose-planning. In spite of having different VMAT optimization approach dual arc and two combined independent-single-arcs provided very similar target coverage, while dual arc improved sparing of organs-at-risk. Similar treatment delivery times were observed for DA and ISAs VMAT techniques. Conclusion: Single arc is sufficient for prostate, while inefficient in case of head-and-neck dose-planning.Dual arc and two combined independent-single-arcs provided similar PTV coverage, while DA provided better sparing of organs at risk. Continuous...