Growth and form of the mound in Gale Crater, Mars: Slope wind enhanced erosion and transport

Ancient sediments provide archives of climate and habitability on Mars. Gale Crater, the landing site for the Mars Science Laboratory (MSL), hosts a 5-km-high sedimentary mound (Mount Sharp/Aeolis Mons). Hypotheses for mound formation include evaporitic, lacustrine, fluviodeltaic, and aeolian processes, but the origin and original extent of Gale’s mound is unknown. Here we show new measurements of sedimentary strata within the mound that indicate ∼3° outward dips oriented radially away from the mound center, inconsistent with the first three hypotheses. Moreover, although mounds are widely considered to be erosional remnants of a once crater-filling unit, we find that the Gale mound’s current form is close to its maximal extent. Instead we propose that the mound’s structure, stratigraphy, and current shape can be explained by growth in place near the center of the crater mediated by wind-topography feedbacks. Our model shows how sediment can initially accrete near the crater center far from crater-wall katabatic winds, until the increasing relief of the resulting mound generates mound-flank slope winds strong enough to erode the mound. The slope wind enhanced erosion and transport (SWEET) hypothesis indicates mound formation dominantly by aeolian deposition with limited organic carbon preservation potential, and a relatively limited role for lacustrine and fluvial activity. Morphodynamic feedbacks between wind and topography are widely applicable to a range of sedimentary and ice mounds across the Martian surface, and possibly other planets

Characterisation of damage mechanisms in oxide ceramics indented at dynamic and quasi-static strain rates

Ceramic materials are known to display rate dependent behaviour under impact. Tests to establish the strain-rate dependent variations in damage mechanisms have been carried out on debased alumina, an alumina-zirconia composite, and 3Y-TZP. Materials were indented dynamically and quasi-statically using identical sharp hardened steel projectiles while recording the load profile. Characteristics typical of both sharp and blunt indentation types were observed using scanning electron microscopy and piezospectroscopic mapping. At dynamic strain rates both the depth of the indentation and the residual stress in the material were lower than for quasi-static tests. This was attributed to temperature-induced softening of the projectile. Unusual behaviour was observed in the 3Y-TZP samples due to the reversible transformation from tetragonal to monoclinic crystal structures during mechanical loading. These effects and the observed superior mechanical strength against impact suggest that zirconia or zirconia-composite materials may have advantages over debased alumina for application as ceramic armour materials

On the multiplicity of the hyperelliptic integrals

Let $I(t)= \oint_{\delta(t)} \omega$ be an Abelian integral, where $H=y^2-x^{n+1}+P(x)$ is a hyperelliptic polynomial of Morse type, $\delta(t)$ a horizontal family of cycles in the curves $\{H=t\}$, and $\omega$ a polynomial 1-form in the variables $x$ and $y$. We provide an upper bound on the multiplicity of $I(t)$, away from the critical values of $H$. Namely: $ord\ I(t) \leq n-1+\frac{n(n-1)}{2}$if$\deg \omega <\deg H=n+1$. The reasoning goes as follows: we consider the analytic curve parameterized by the integrals along$\delta(t)$of the$n$``Petrov'' forms of$H$(polynomial 1-forms that freely generate the module of relative cohomology of$H$), and interpret the multiplicity of$I(t)$as the order of contact of$\gamma(t)$and a linear hyperplane of$\textbf C^ n$. Using the Picard-Fuchs system satisfied by$\gamma(t)$, we establish an algebraic identity involving the wronskian determinant of the integrals of the original form$\omega$along a basis of the homology of the generic fiber of$H$. The latter wronskian is analyzed through this identity, which yields the estimate on the multiplicity of$I(t)$. Still, in some cases, related to the geometry at infinity of the curves$\{H=t\} \subseteq \textbf C^2$, the wronskian occurs to be zero identically. In this alternative we show how to adapt the argument to a system of smaller rank, and get a nontrivial wronskian. For a form$\omega$of arbitrary degree, we are led to estimating the order of contact between$\gamma(t)$and a suitable algebraic hypersurface in$\textbf C^{n+1}$. We observe that$ord I(t)$grows like an affine function with respect to$\deg \omega$.Comment: 18 page

Sex-selective abortions and infant mortality in India: the role of parents’ stated son preference

In India, millions of female foetuses have been aborted since the 1980s alongside an abnormally high infant girl mortality rate; this has generated a vast literature exploring the root causes of son preference. The literature is sparse, however, on how the decisions to abort or neglect girls are made. This paper examines mothers’ and fathers’ respective roles behind those decisions. Using NFHS-3 data, we show that sex- selective abortions are most commonly used if both spouses or if only the fathers prefer sons, while sex-selective neglect is used if only the mothers prefer sons

The derived category of surface algebras: the case of the torus with one boundary component

In this paper we refine the main result of a previous paper of the author with Grimeland on derived invariants of surface algebras. We restrict to the case where the surface is a torus with one boundary component and give an easily computable derived invariant for such surface algebras. This result permits to give answers to open questions on gentle algebras: it provides examples of gentle algebras with the same AG-invariant (in the sense of Avella-Alaminos and Geiss) that are not derived equivalent and gives a partial positive answer to a conjecture due to Bobi\'nski and Malicki on gentle $2$-cycles algebras.Comment: 22 pages, a mistake concerning the computation of the mapping class group has been fixed, version 3: 25 pages, to appear in Algebras and Representation Theor

DynPeak : An algorithm for pulse detection and frequency analysis in hormonal time series

The endocrine control of the reproductive function is often studied from the analysis of luteinizing hormone (LH) pulsatile secretion by the pituitary gland. Whereas measurements in the cavernous sinus cumulate anatomical and technical difficulties, LH levels can be easily assessed from jugular blood. However, plasma levels result from a convolution process due to clearance effects when LH enters the general circulation. Simultaneous measurements comparing LH levels in the cavernous sinus and jugular blood have revealed clear differences in the pulse shape, the amplitude and the baseline. Besides, experimental sampling occurs at a relatively low frequency (typically every 10 min) with respect to LH highest frequency release (one pulse per hour) and the resulting LH measurements are noised by both experimental and assay errors. As a result, the pattern of plasma LH may be not so clearly pulsatile. Yet, reliable information on the InterPulse Intervals (IPI) is a prerequisite to study precisely the steroid feedback exerted on the pituitary level. Hence, there is a real need for robust IPI detection algorithms. In this article, we present an algorithm for the monitoring of LH pulse frequency, basing ourselves both on the available endocrinological knowledge on LH pulse (shape and duration with respect to the frequency regime) and synthetic LH data generated by a simple model. We make use of synthetic data to make clear some basic notions underlying our algorithmic choices. We focus on explaining how the process of sampling affects drastically the original pattern of secretion, and especially the amplitude of the detectable pulses. We then describe the algorithm in details and perform it on different sets of both synthetic and experimental LH time series. We further comment on how to diagnose possible outliers from the series of IPIs which is the main output of the algorithm.Comment: Nombre de pages : 35 ; Nombre de figures : 16 ; Nombre de tableaux :

Barrier properties of films of pea starch associated with xanthan gum and glycerol

O objetivo do trabalho foi avaliar as propriedades de barreira e a solubilidade de biofilmes obtidos a partir de amido de ervilha de alto teor de amilose em associação à goma xantana e glicerol. Soluções filmogênicas (SF) com diferentes teores de amido de ervilha (3, 4 e 5%), goma xantana (0, 0,05 e 0,1%) e glicerol (proporção glicerol-amido de 1:5 P/P) foram estudadas. As SF foram obtidas por ebulição (5 minutos), seguida de autoclavagem por 1 hora a 120 ºC e os filmes foram preparados por casting. O aumento da concentração de amido e de glicerol na composição causou aumento da espessura e da solubilidade dos filmes em água. O plastificante gerou ainda elevação dos coeficientes de permeabilidade ao vapor d'água e ao oxigênio. O aumento da concentração da goma xantana não interferiu nas propriedades estudadas. Os biofilmes obtidos a partir de amido de ervilha verde, associado ou não à goma xantana e glicerol, se comparados com filmes de amido de ervilha amarelas e outras fontes de amido, apresentaram boa barreira ao oxigênio e ao vapor d'água e baixa solubilidade em água.The aim of this work was to evaluate the barrier properties and solubility of biofilms made from wrinkled pea starch with high amylose content in association with xanthan gum and glycerol. Filmogenic solution (FS) with different levels of pea starch (3, 4 and 5%), xanthan gum (0, 0.05 and 0.1%) and glycerol (glycerol-starch 1:5 W/W) were tested. FS was obtained by boiling (5 minutes), autoclaving for 1 hour at 120 ºC and the films were prepared by casting. The increased concentration of starch and glycerol in the composition caused increases in thickness of the films and in their solubility in water. The plasticizer also generated higher coefficients of water vapor and oxygen permeabilities to water vapor and to oxygen. The increasing concentration of xanthan gum did not interfere in the properties studied. Biofilms produced with wrinkled pea starch, with or without xanthan gum and glycerol, showed better barrier to oxygen and water vapor and low solubility in water, in comparison with films of yellow pea starch and other starch sources.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Perceptions of knowledge sharing among small family firm leaders: a structural equation model

Small family firms have many unique relational qualities with implications for how knowledge is passed between individuals. Extant literature posits leadership approach as important in explaining differences in knowledge-sharing climate from one firm to another. This study investigates how leadership approaches interact with family influence to inform perceptions of knowledge sharing. We utilize survey data (n = 110) from owner-managers of knowledge-intensive small family firms in Scotland. Our findings present a choice in leadership intention, contrasting organization-focused participation against family-influenced guidance. Insight is offered on the implications of this leadership choice at both organizational and familial level

Self-similar disk packings as model spatial scale-free networks

The network of contacts in space-filling disk packings, such as the Apollonian packing, are examined. These networks provide an interesting example of spatial scale-free networks, where the topology reflects the broad distribution of disk areas. A wide variety of topological and spatial properties of these systems are characterized. Their potential as models for networks of connected minima on energy landscapes is discussed.Comment: 13 pages, 12 figures; some bugs fixed and further discussion of higher-dimensional packing