Hot-spot tectonics of Eistla Regio, Venus: Results from Magellan images and Pioneer Venus gravity

Eistla Regio (ER) is a broad, low, discontinuous topographic rise striking roughly EW at low northern latitudes of Venus. Some 2000 x 7000 km in dimensions, it is the third largest rise in planform on Venus after Aphrodite Terra and Beta Phoebe Regiones. These rises are the key physiographic elements in a hot spot model of global tectonics including transient plume behavior. Since ER is the first such rise viewed by Magellan and the latitude is very favorable for Pioneer Venus gravity studies, some of the predictions of a time dependent hot spot model are tested. Western ER is defined as the rise including Gula and Sif Mons and central ER as that including Sappho Patera. Superior conjunction prevented Magellan from returning data on eastern ER (Pavlova) during the first mapping cycle. It is concluded that the western and central portions of ER, while part of the same broad topographic rise and tectonic framework, have distinctly different surface ages and gravity signatures. The western rise, including Gula and Sif Mons, is the expression of deep seated uplift with volcanism limited to the individual large shields. The eastern portion has been widely resurfaced more recently by thermal anomalies in the mantle

Lunar Mantle Structure and Composition Inferred From Apollo 12 -- Explorer 35 Electromagnetic Sounding

Constraints on the interior structure of the Moon have been derived from its inductive response, principally as measured by the magnetic transfer function (TF) between the distantly orbiting Explorer 35 satellite and the Apollo 12 surface station. The most successful prior studies used a dataset 0.01-1 mHz, so the lunar response could be modeled as a simple dipole. However, earlier efforts also produced transfer functions up to 40 mHz. The smaller electromagnetic skin depth at higher frequency would better resolve the uppermost mantle - where key information about primitive lunar evolution may still be preserved - but requires a multipole treatment. I compute new profiles of electrical conductivity vs depth using both the low-frequency and the full-bandwidth ranges of published Apollo-Explorer TFs. I derive temperature profiles at depths >400 km (<1 mHz) consistent with conductive heat loss and expectations of the iron (and possibly water) content of the mantle. The near-constant iron fraction (Mg# 81 +/- 7) implies either efficient mixing, due to now-defunct convection or perhaps incomplete overturn of gravitationally unstable cumulates following crystallization of the magma ocean. In contrast, the full-bandwidth analysis produced a different conductivity profile that could not be realistically matched by conduction, convection, partial melting, or simple considerations of lateral heterogeneity. I conclude that the TF method at the Moon is unreliable >>1 mHz. Future EM sounding using the magnetotelluric method can operate up to 100s Hz and is largely insensitive to multipole effects, resolving structure to 100 km or less

Interpretation of the northern boundary of Ishtar Terra from Magellan images and altimetry

Part of the controversy on the origin of western Ishtar Terra (IT) concerns the nature of Uorsar Rupes (UR), the northern boundary of IT. In the hypothesis of lithospheric convergence and underthrusting, UR is held to be the main boundary thrust fault at the toe of an accretionary wedge. A topographic rise parallel to the scarp was interpreted as a flexural bulge similar to those of terrestrial subduction zones, and quantitative models of this feature seemed broadly consistent with the expected lithospheric structure of Venus. In the alternative mantle upwelling hypothesis for western IT, the outer margins of the highland are thought to be collapsing, and UR has been interpreted as a normal fault. Herein, Magellan images and altimetry are interpreted for this region and the hypothesis that a flexural signature can be distinguished is reassessed. The Magellan images of IT show evidence of crustal shortening adjacent to UR, but extension and burial dominate northwards. Altimetric profiles display the same long wavelength trends visible in Venera data, but no clear evidence of the lithospheric flexure. A model of regional extension and burial is herein favored, but regional compression cannot be ruled out

Part 1: Aspects of lithospheric evolution on Venus. Part 2: Thermal and collisional histories of chondrite parent bodies

The geological evolution of distinctly different kinds of solar system objects is addressed. Venus has been observed over the past decade by orbital radars on both American and Soviet spacecraft. These surface measurements provide clues to the structure and evolution of the lithosphere. The parent bodies of chondritic meteorites, thought to resemble asteroids, represent the other end of the size spectrum of terrestrial objects. Their early thermal and collisional histories may be constrained by the chemical and textural record preserved in meteorite samples. Impact craters on Venus have been observed by the Soviet Venera 15/16 spacecraft. A formalism is presented by which the size-frequency distribution of impact craters may be used to estimate upper bounds on the mean global rates of volcanic resurfacing and lithospheric recycling on that planet over the past several hundred million years. The impact crater density reported from Venera observations, if valid for the entire Venus surface, indicates a mean volcanic flux no greater than 2 cu km/y, corresponding to a maximum average rate of resurfacing of about 4 km/b.y. For the lowest estimated mean crater retention age of the surface of Venus imaged by Venera 15/16, the rate of lithospheric recycling on Venus does not exceed 1.5 sq km/y. Ordinary chondrite meteorites show textural and chemical patterns indicative of varying intensities of thermal metamorphism. The conventional onion-shell model, which envisions highly metamorphosed material in the core and less intensely heated rocks near the surface, predicts an inverse relation between peak temperature and cooking rate, but none has been observed. A metamorphosed-planetesimal model is devised to explain this discrepancy, whereby heating occurs in planetesimals a few kilometers in radius which then accrete to form 100-km-radius parent bodies. Cooling rates are then randomly controlled by burial depth. Thermal and collisional constraints are examined, and the model is found to be applicable only to highly insulating Al-26-rich planetesimals that remain closely aggregated upon accretion. An alternative model is presented, in which onion-shell parent bodies are collisionally fragmented during metamorphism and then gravitationally reassembled. If reassembly times are short, then cooling rates would be determined by burial depth in the reaccreted parent body. This model, unlike previous ones, can explain both coherent and incoherent cooling of Breccia clasts by collisions during or after metamorphism, respectively

Bibliography on heavy vehicle dynamics

http://deepblue.lib.umich.edu/bitstream/2027.42/108243/1/103019.pdfDescription of 103019.pdf : Bibliograph

I. Aspects of lithospheric evolution on Venus. ; II. Thermal and collisional histories of chondrite parent bodies

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1989.Includes bibliographical references.by Robert E. Grimm.Ph.D

Durvalumab for the Treatment of Locally Advanced, Unresectable, Stage III Non-Small Cell Lung Cancer:An Evidence Review Group Perspective of a NICE Single Technology Appraisal

As part of the Single Technology Appraisal (STA) process, the National Institute for Health and Care Excellence (NICE) invited the manufacturer (AstraZeneca) of durvalumab (IMFINZI(TM)) to submit evidence for the clinical and cost effectiveness of durvalumab for the treatment of patients with locally advanced, unresectable, stage III non-small cell lung cancer whose tumours express programmed death-ligand 1 (PD-L1) on >= 1% of tumour cells and whose disease has not progressed after platinum-based chemoradiation therapy. Kleijnen Systematic Reviews Ltd, in collaboration with Maastricht University Medical Centre, was commissioned to act as the independent Evidence Review Group (ERG). This paper summarises the company submission (CS), presents the ERG's critical review on the clinical- and cost-effectiveness evidence in the CS, highlights the key methodological considerations, and describes the development of the NICE guidance by the Appraisal Committee. The CS included a systematic review that identified one randomised controlled trial, comparing durvalumab with SoC. Participants with tumours expressing PD-L1 on >= 1% of tumour cells accounted for approximately 40% of the total participants. In this subgroup, a benefit in progression-free survival (PFS) [hazard ratio (HR) 0.44, 95% confidence interval (CI) 0.31-0.63] and overall survival (HR 0.54, 95% CI 0.35-0.81) was reported. Adverse events were comparable between both treatments, but more serious adverse events were reported for durvalumab (64/213 [30%] vs. 18/90 [20%]). The ERG's concerns regarding the economic analysis included a likely overestimation of PFS for the durvalumab arm, the choice of timepoint for treatment waning, as well as the way treatment waning was incorporated in the model, and potential overestimation of utility values without applying an age- or treatment-related decrement. The revised ERG base-case resulted in a deterministic incremental cost-effectiveness ratio of 50,238 pound per quality-adjusted life-year gained, with substantial remaining uncertainty. NICE recommended durvalumab as an option for use within the Cancer Drugs Fund only in a subpopulation (concurrent platinum-based chemoradiation therapy) with a commercially managed access agreement in place

Nitrate removal in stream ecosystems measured by 15N addition experiments: Denitrification

We measured denitrification rates using a field 15NO3− tracer-addition approach in a large, cross-site study of nitrate uptake in reference, agricultural, and suburban-urban streams. We measured denitrification rates in 49 of 72 streams studied. Uptake length due to denitrification (SWdenn) ranged from 89 m to 184 km (median of 9050 m) and there were no significant differences among regions or land-use categories, likely because of the wide range of conditions within each region and land use. N2 production rates far exceeded N2O production rates in all streams. The fraction of total NO3− removal from water due to denitrification ranged from 0.5% to 100% among streams (median of 16%), and was related to NH4+ concentration and ecosystem respiration rate (ER). Multivariate approaches showed that the most important factors controlling SWden were specific discharge (discharge / width) and NO3− concentration (positive effects), and ER and transient storage zones (negative effects). The relationship between areal denitrification rate (Uden) and NO3− concentration indicated a partial saturation effect. A power function with an exponent of 0.5 described this relationship better than a Michaelis-Menten equation. Although Uden increased with increasing NO3− concentration, the efficiency of NO3− removal from water via denitrification declined, resulting in a smaller proportion of streamwater NO3− load removed over a given length of stream. Regional differences in stream denitrification rates were small relative to the proximate factors of NO3− concentration and ecosystem respiration rate, and land use was an important but indirect control on denitrification in streams, primarily via its effect on NO3− concentration

VISION User Guide - VISION (Verifiable Fuel Cycle Simulation) Model

The purpose of this document is to provide a guide for using the current version of the Verifiable Fuel Cycle Simulation (VISION) model. This is a complex model with many parameters; the user is strongly encouraged to read this user guide before attempting to run the model. This model is an R&D work in progress and may contain errors and omissions. It is based upon numerous assumptions. This model is intended to assist in evaluating “what if” scenarios and in comparing fuel, reactor, and fuel processing alternatives at a systems level for U.S. nuclear power. The model is not intended as a tool for process flow and design modeling of specific facilities nor for tracking individual units of fuel or other material through the system. The model is intended to examine the interactions among the components of a fuel system as a function of time varying system parameters; this model represents a dynamic rather than steady-state approximation of the nuclear fuel system. VISION models the nuclear cycle at the system level, not individual facilities, e.g., “reactor types” not individual reactors and “separation types” not individual separation plants. Natural uranium can be enriched, which produces enriched uranium, which goes into fuel fabrication, and depleted uranium (DU), which goes into storage. Fuel is transformed (transmuted) in reactors and then goes into a storage buffer. Used fuel can be pulled from storage into either separation of disposal. If sent to separations, fuel is transformed (partitioned) into fuel products, recovered uranium, and various categories of waste. Recycled material is stored until used by its assigned reactor type. Note that recovered uranium is itself often partitioned: some RU flows with recycled transuranic elements, some flows with wastes, and the rest is designated RU. RU comes out of storage if needed to correct the U/TRU ratio in new recycled fuel. Neither RU nor DU are designated as wastes. VISION is comprised of several Microsoft Excel input files, a Powersim Studio core, and several Microsoft Excel output files. All must be co-located in the same folder on a PC to function. We use Microsoft Excel 2003 and have not tested VISION with Microsoft Excel 2007. The VISION team uses both Powersim Studio 2005 and 2009 and it should work with either

Nuclear factor κB-inducing kinase activation as a mechanism of pancreatic β cell failure in obesity

The nuclear factor κB (NF-κB) pathway is a master regulator of inflammatory processes and is implicated in insulin resistance and pancreatic β cell dysfunction in the metabolic syndrome. Whereas canonical NF-κB signaling is well studied, there is little information on the divergent noncanonical NF-κB pathway in the context of pancreatic islet dysfunction. Here, we demonstrate that pharmacological activation of the noncanonical NF-κB-inducing kinase (NIK) disrupts glucose homeostasis in zebrafish in vivo. We identify NIK as a critical negative regulator of β cell function, as pharmacological NIK activation results in impaired glucose-stimulated insulin secretion in mouse and human islets. NIK levels are elevated in pancreatic islets isolated from diet-induced obese (DIO) mice, which exhibit increased processing of noncanonical NF-κB components p100 to p52, and accumulation of RelB. TNF and receptor activator of NF-κB ligand (RANKL), two ligands associated with diabetes, induce NIK in islets. Mice with constitutive β cell-intrinsic NIK activation present impaired insulin secretion with DIO. NIK activation triggers the noncanonical NF-κB transcriptional network to induce genes identified in human type 2 diabetes genome-wide association studies linked to β cell failure. These studies reveal that NIK contributes a central mechanism for β cell failure in diet-induced obesity