Large-volume lava flow fields on Venus: Dimensions and morphology

Of all the volcanic features identified in Magellan images, by far the most extensive and really important are lava flow fields. Neglecting the widespread lava plains themselves, practically every C1-MIDR produced so far contains several or many discrete lava flow fields. These range in size from a few hundred square kilometers in area (like those fields associated with small volcanic edifices for example), through all sizes up to several hundred thousand square kilometers in extent (such as many rift related fields). Most of these are related to small, intermediate, or large-scale volcanic edifices, coronae, arachnoids, calderas, fields of small shields, and rift zones. An initial survey of 40 well-defined flow fields with areas greater than 50,000 sq km (an arbitrary bound) has been undertaken. Following Columbia River Basalt terminology, these have been termed great flow fields. This represents a working set of flow fields, chosen to cover a variety of morphologies, sources, locations, and characteristics. The initial survey is intended to highlight representative flow fields, and does not represent a statistical set. For each flow field, the location, total area, flow length, flow widths, estimated flow thicknesses, estimated volumes, topographic slope, altitude, backscatter, emissivity, morphology, and source has been noted. The flow fields range from about 50,000 sq km to over 2,500,000 sq km in area, with most being several hundred square kilometers in extent. Flow lengths measure between 140 and 2840 km, with the majority of flows being several hundred kilometers long. A few basic morphological types have been identified

Conduction of topologically-protected charged ferroelectric domain walls

We report on the observation of nanoscale conduction at ferroelectric domain walls in hexagonal HoMnO3 protected by the topology of multiferroic vortices using in situ conductive atomic force microscopy, piezoresponse force microscopy, and kelvin-probe force microscopy at low temperatures. In addition to previously observed Schottky-like rectification at low bias [Phys. Rev. Lett., 104, 217601 (2010)], conductance spectra reveal that negatively charged tail-to-tail walls exhibit enhanced conduction at high forward bias, while positively charged head-to-head walls exhibit suppressed conduction at high reverse bias. Our results pave the way for understanding the semiconducting properties of the domains and domain walls in small-gap ferroelectrics.Comment: 8 pages, 4 figure

Structural Tightness and Social Conformity: Varying the Source of External Influence

This study reconceptualizes the term structural tightness in order to clarify the equivocal empirical findings in cross-cultural conformity research. Structural tightness is defined as the ability to impose collective role expectations on members of a community. The results often exploratory test of the theoretical proposal are reported and the implications for fiuture research are discussed. In general, the findings suggest that further investigation of the theoretical proposal is warranted. Researchers working within the social structure and personality framework continue to generate useful pure and applied research hypotheses (House, 1981; Spenner, 1988; Turner, 1988). Such advances are sustained by research that emphasizes aspects of societies in relation to aspects of individual personality (House, 1981:526. Emphasis in original). The research reported here follows this tradition and focuses on one component of a promising cross-cultural model where equivocal empirical findings have stalled further research. This paper has two specific objectives. First, it forwards a reconceptualization of the term structural tightness . In doing so a social structural dimension pertinent to advancing the cross-cultural research model under consideration is specified. Secondly, the results of an exploratory study testing some implications of the theoretical proposal are reported

Tests for cream sediment

Commercial milk plants have employed the sediment test for milk for many years. In fact, the milk sediment test has its place on the milk score card. The amount of sediment is always determined in scoring milk. The test is extremely simple; it consists of passing 1 pint of milk through a sediment tester and catching the sediment present in the milk on a circular pad 1 inch in diameter. The application of a sediment test to cream, on the other hand, has been attempted only very recently. A test as simple as that for milk is impossible. The cream’s high fat content necessitates warming it to melt the fat so that the sample will filter easily; the variable acidity of cream for butter-making necessitates the use of a neutralizing agent, in many instances in order that the filter pad will not clog. Because of the high fat content of the cream it is imperative to use less than a pint in order to reduce the cost and eliminate the handling of a bulky sample after dilution

Quantifying the Role of Atmospheric Forcing in Ice Edge Retreat and Advance Including Wind-Wave Coupling

LONG-TERM GOALS: 1. Representing surface fluxes and ocean waves in coupled models in the Beaufort and Chukchi Seas. 2. Understand the physics of heat and mass transfer from the ocean to the atmosphere. 3. Improve forecasting of waves on the open ocean and in the marginal ice zone.Award Numbers: N0001413WX20830 (Guest) N0001413IP20046 (Fairall, Persson

Constrained Shape Optimization of Cold-formed Steel Columns

The objective of this paper is to introduce appropriate constraints in the shape optimization of a cold- formed steel column such that the resulting optimized shapes retain the strength benefits of unconstrained optimal solutions combined with practical manufacturing and constructional needs. Unconstrained shape optimization of cold-formed steel columns, where the cross-section that maximizes axial capacity is found, has previously been performed. Here, practical manufacturing and construction constraints are introduced into the optimization algorithm. Members with three lengths: 2 ft, 4 ft, and 16 ft, are considered. Optimized sections from multiple runs show uniformity and bear a close resemblance to unconstrained results. A point-symmetric ‘S’-shaped section has maximum capacity for long columns and a singly-symmetric ‘∑’-shaped section with complex lips performs best for shorter columns. The observed strength loss from the unconstrained optimal design, to the constrained optimal design, is within ten percent. A simultaneous perturbation stochastic approximation algorithm, with the idea of injecting randomness in the gradient approximation to save computational cost, is adopted as the local optimizer. A systematic survey on a family of lipped channel cross-sections using the same amount of material was carried out. Comparison reveals that the optimized shapes have much larger capacities and exhibit the potential to seed a new generation of commercial products

The orbit rigidity matrix of a symmetric framework

A number of recent papers have studied when symmetry causes frameworks on a graph to become infinitesimally flexible, or stressed, and when it has no impact. A number of other recent papers have studied special classes of frameworks on generically rigid graphs which are finite mechanisms. Here we introduce a new tool, the orbit matrix, which connects these two areas and provides a matrix representation for fully symmetric infinitesimal flexes, and fully symmetric stresses of symmetric frameworks. The orbit matrix is a true analog of the standard rigidity matrix for general frameworks, and its analysis gives important insights into questions about the flexibility and rigidity of classes of symmetric frameworks, in all dimensions. With this narrower focus on fully symmetric infinitesimal motions, comes the power to predict symmetry-preserving finite mechanisms - giving a simplified analysis which covers a wide range of the known mechanisms, and generalizes the classes of known mechanisms. This initial exploration of the properties of the orbit matrix also opens up a number of new questions and possible extensions of the previous results, including transfer of symmetry based results from Euclidean space to spherical, hyperbolic, and some other metrics with shared symmetry groups and underlying projective geometry.Comment: 41 pages, 12 figure

Mk-801 Treatment Affects Glycolysis In Oligodendrocytes More Than In Astrocytes And Neuronal Cells: Insights For Schizophrenia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Schizophrenia is a debilitating mental disorder, affecting more than 30 million people worldwide. As a multifactorial disease, the underlying causes of schizophrenia require analysis by multiplex methods such as proteomics to allow identification of whole protein networks. Previous post-mortem proteomic studies on brain tissues from schizophrenia patients have demonstrated changes in activation of glycolytic and energy metabolism pathways. However, it is not known whether these changes occur in neurons or in glial cells. To address this question, we treated neuronal, astrocyte, and oligodendrocyte cell lines with the NMDA receptor antagonist MK-801 and measured the levels of six glycolytic enzymes by Western blot analysis. MK-801 acts on the glutamatergic system and has been proposed as a pharmacological means of modeling schizophrenia. Treatment with MK-801 resulted in significant changes in the levels of glycolytic enzymes in all cell types. Most of the differences were found in oligodendrocytes, which had altered levels of hexokinase 1 (HK1), enolase 2 (ENO2), phosphoglycerate kinase (PG, and phosphoglycerate mutase 1 after acute MK-801 treatment (8 h), and HK1, ENO2, PGK, and triosephosphate isomerase (TPI) following long term treatment (72 h). Addition of the antipsychotic clozapine to the cultures resulted in counter-regulatory effects to the MK-801 treatment by normalizing the levels of ENO2 and PGK in both the acute and long term cultures. In astrocytes, MK-801 affected only aldolase C (ALDOC) under both acute conditions and HK1 and ALDOC following long term treatment, and TPI was the only enzyme affected under long term conditions in the neuronal cells. In conclusion, MK-801 affects glycolysis in oligodendrocytes to a larger extent than neuronal cells and this may be modulated by antipsychotic treatment. Although cell culture studies do not necessarily reflect the in vivo pathophysiology and drug effects within the brain, these results suggest that neurons, astrocytes, and oligodendrocytes are affected differently in schizophrenia. Employing in vitro models using neurotransmitter agonists and antagonists may provide new insights about the pathophysiology of schizophrenia which could lead to a novel system for drug discovery.9Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAEPEX UNICAMP [519.292]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Tzitz\'eica transformation is a dressing action

We classify the simplest rational elements in a twisted loop group, and prove that dressing actions of them on proper indefinite affine spheres give the classical Tzitz\'eica transformation and its dual. We also give the group point of view of the Permutability Theorem, construct complex Tzitz\'eica transformations, and discuss the group structure for these transformations