Reciprocity relation for the vector radiative transport equation and its application to diffuse optical tomography with polarized light

We derive a reciprocity relation for vector radiative transport equation (vRTE) that describes propagation of polarized light in multiple-scattering media. We then show how this result, together with translational invariance of a plane-parallel sample, can be used to compute efficiently the sensitivity kernel of diffuse optical tomography (DOT) by Monte Carlo simulations. Numerical examples of polarization-selective sensitivity kernels thus computed are given.Comment: 5 pages, 3 figure

Technological Change and Economy in the Epipalaeolithic: Assessing the Shift from Early to Middle Epipalaeolithic at Kharaneh IV

Epipalaeolithic hunter-gatherer communities in the Southern Levant exhibit numerous complex trends that suggest that the transition to the Neolithic was patchy and protracted. This paper explores the changing nature of occupation at the Epipalaeolithic site Kharaneh IV, Jordan, through an in-depth analysis of the lithic and faunal assemblages. Focusing on the analysis of a single deep sounding (unit AS42), we address how Kharaneh IV occupations link to the local landscape and environmental changes. As an aggregation site, Kharaneh IV represents an interesting locale to explore the changing nature of aggregation and social cohesion prior to the origins of agriculture, as well as changes in technology and subsistence between the Early and Middle Epipalaeolithic. We explore the tempo and nature of transition from one archaeological culture to the next through changes in technology and how this reflects the people making and using tools, to understand how foragers adapted to a changing landscape

Women in the wake: expanding the legacy of Chico Mendes in Brazil’s environmental movement

Since the death of Chico Mendes three decades ago, nearly half of the Amazon forest area has been conserved through the collective sacrifice and struggle of thousands of forest-reliant families in Brazil, twined with political will and dense scientific and technical capacity. The key position that once marginalized, rural women have played in this struggle, however, is often obscured. This paper describes the role of women, some eminent and others lesser known, in the conservation movement inspired by Chico Mendes in Brazil. Thirty years ago, women were not permitted to be union members; today, 40% of the National Council of Extractivist Populations (CNS) leadership is female, and 25% of conservation units are led by women. Brazilian women occupy positions across the full spectrum of politics from grassroots to crucial positions in government, unions and civil society organizations. As women have gained power, they have also become targets. Of the 818 assassinations recorded by the Comissão Pastoral da Terra” (CPT) between 1997 and 2017, 7% have been women. Their deaths have not been forgotten. During 2017’s March of the Margaridas, in support of women’s rights and in remembrance of those who have died for the cause, an estimated one hundred thousand women have participated. Since Mendes’ death, the movement to conserve forests and secure land for smallholders in Brazil has not abated, but grown and evolved through cross-sectoral collaborations, intergenerational exchange, strategic advocacy across vast geographic areas, and shared bonds born of struggle. The paper highlights the vital role of women in expanding and concretizing a globally significant forest conservation movement sparked by a man with a vision

Meat outside the freezer: Drying, smoking, salting and sealing meat in fat at an Epipalaeolithic megasite in eastern Jordan

Even though pivotal for understanding many aspects of human behaviour, preservation and storage of animal resources has not received great attention from archaeologists. One could argue that the main problem lies in the difficulties of demonstrating meat storage archaeologically due to the lack of direct evidence. This paper represents an attempt to refine zooarchaeological methods for the recognition of meat preservation and storage at prehistoric sites. Drawing on the faunal assemblage from Kharaneh IV, an Early/Middle Epipalaeolithic aggregation site in eastern Jordan, this study demonstrates that a combination of taphonomic and contextual analyses alongside ethnographic information may indeed lead archaeologists to insights not directly available from the archaeological record. The empirical evidence presented here contributes to the archaeological visibility of meat preservation and storage, providing a clearer concept of the nature of these practices in pre-agricultural societies

Reentrant Metallic Behavior of Graphite in the Quantum Limit

Magnetotransport measurements performed on several well-characterized highly oriented pyrolitic graphite and single crystalline Kish graphite samples reveal a reentrant metallic behavior in the basal-plane resistance at high magnetic fields, when only the lowest Landau levels are occupied. The results suggest that the quantum Hall effect and Landau-level-quantization-induced superconducting correlations are relevant to understand the metallic-like state(s) in graphite in the quantum limit.Comment: 4 pages, 5 figure

Multi-modal vibration amplitudes of taut inclined cables due to direct and/or parametric excitation

AbstractCables are often prone to potentially damaging large amplitude vibrations. The dynamic excitation may be from external loading or motion of the cable ends, the latter including direct excitation, normally from components of end motion transverse to the cable, and parametric excitation induced by axial components of end motion causing dynamic tension variations. Geometric nonlinearity can be important, causing stiffening behaviour and nonlinear modal coupling. Previous analyses of the vibrations, often neglecting sag, have generally dealt with direct and parametric excitation separately or have reverted to numerical solutions of the responses. Here a nonlinear cable model is adopted, applicable to taut cables such as on cable-stayed bridges, that allows for cable inclination, small sag (such that the vibration modes are similar to those of a taut string), multiple modes in both planes and end motion and/or external forcing close to any natural frequency. Based on the method of scaling and averaging it is found that, for sinusoidal inputs and positive damping, non-zero steady state responses can only occur in the modes in each plane with natural frequencies close to the excitation frequency and those with natural frequencies close to half this frequency. Analytical solutions, in the form of non-dimensional polynomial equations, are derived for the steady state vibration amplitudes in up to three modes simultaneously: the directly excited mode, the corresponding nonlinearly coupled mode in the orthogonal plane and a parametrically excited mode with half the natural frequency. The stability of the solutions is also identified. The outputs of the equations are consistent with previous results, where available. Example results from the analytical solutions are presented for a typical inclined bridge cable subject to vertical excitation of the lower end, and they are validated by numerical integration of the equations of motion and against some previous experimental results. It is shown that the modal interactions and sag (although very small) affect the responses significantly

Effect of temperature on the passive state of Alloy 31 in a LiBr solution: Passivation and Mott-Schottky analysis

The passive behaviour of Alloy 31, a highly‐alloyed austenitic stainless steel (UNS N08031), has been investigated in a LiBr heavy brine (700 g/l) at different temperatures using potentiostatic polarisation and Mott‐Schottky analysis. Cation vacancies have been found to be the dominant defect in the passive films formed on Alloy 31. An increase in temperature enhanced the generation of cation vacancies at the film/solution interface and raised the steady‐state passive current density. The density of defects within the passive film also increased significantly with temperature, making the film more conductive and less protective against localised attacks

Limitations to the use of tooth wear as a means of ageing Eurasian badgers, Meles meles

L'observation de blaireaux d'ages connus montre que le critère d'usure des dents n'est pas une mesure fiable pour les blaireaux d'une population à Wytham (Oxfordshire).Cette divergence de résultats semble due aux variations du régime alimentaire qui entrainent des taux d'usure différent

Passive and transpassive behaviour of Alloy 31 in a heavy brine LiBr solution

The passive and transpassive behaviour of Alloy 31, a highly alloyed austenitic stainless steel (UNS N08031), has been investigated in a LiBr heavy brine solution (400 g/l) at 25 °C using potentiostatic polarisation combined with electrochemical impedance spectroscopy and Mott-Schottky analysis. The passive film formed on Alloy 31 has been found to be p-type and/or n-type in electronic character, depending on the film formation potential. The thickness of the film formed at potentials within the passive region increases linearly with applied potential. The film formed at transpassive potentials is thinner and more conductive than the film formed within the passive region. These observations are consistent with the predictions of the Point Defect Model for passive and transpassive films on metals and alloys