310 research outputs found
La dette: les 'Tirailleurs sénégalais' pendant la Première Guerre mondiale ou le destin de ceux qui viennent d'ailleurs
The Arabana people, water and developing cultural indicators for country
Water is of paramount importance to the Arabana people who live in the Kati Thanda-Lake Eyre region. Assessing the ongoing condition of aquatic ecosystems is an important part of management. Development of indicator frameworks that can incorporate both scientific and cultural values can ensure Indigenous involvement in management, but also facilitate ways in which local and traditional knowledge can be acknowledged as being of value. This project aimed to identify and document the values and indicators for water systems held by the Arabana people with the view to developing ideas about how future assessments across the whole region may: (i) engage with and then, (ii) build a template for cultural indicators across the whole region. This project was implemented using Indigenist and participant methodologies. Arabana people were employed as co-researchers. Three field trips and meetings were held to identify Arabana values for, and indicators about, water in their country. Results indicate that Arabana people value water in multiple ways including for survival, culture and identity. Interestingly, Arabana people also valued water variability and its absence: historical, dry or degraded water sites were noted as significant. Arabana people used a number of indicators or ‘signs’ to assess the ongoing condition of a site. This included flora, fauna, soil, knowledge, history, use, and pressure indicators. In many ways, the cultural indicators used by Arabana people have complementarity with scientific indicators and thus have potential to be built on and then implemented in conjunction with other indicator suites. A cultural indicator schemata is presented as is a co-engagement model for use in wider assessments with other Indigenous groups. However, this research concludes that it is not possible to develop a generic template for integration of all indicators across the region and questions whether or not this is really necessary. Ultimately, what is required is funding and investment into each Indigenous group across the Kati Thanda–Lake Eyre region to support each group to develop their own specific schemata (based potentially on the one we suggest here), and then allocation of funds to train and employ Indigenous people to implement them. The knowledge set built over time in this manner, especially if grounded in the principles of co-existence rather than integration, will also facilitate the conditions for effective and adaptive management. It will be a true complement to scientific indicators and knowledge, while respecting and incorporating Indigenous people aspirations in the region.Nursey-Bray. Melissa, Arabana Aboriginal Corporation, Primary Industries and Regions (SA), SARD
From Forbidden Coronal Lines to Meaningful Coronal Magnetic Fields
We review methods to measure magnetic fields within the corona using the
polarized light in magnetic-dipole (M1) lines. We are particularly interested
in both the global magnetic-field evolution over a solar cycle, and the local
storage of magnetic free energy within coronal plasmas. We address commonly
held skepticisms concerning angular ambiguities and line-of-sight confusion. We
argue that ambiguities are in principle no worse than more familiar remotely
sensed photospheric vector-fields, and that the diagnosis of M1 line data would
benefit from simultaneous observations of EUV lines. Based on calculations and
data from eclipses, we discuss the most promising lines and different
approaches that might be used. We point to the S-like [Fe {\sc XI}] line (J=2
to J=1) at 789.2nm as a prime target line (for ATST for example) to augment the
hotter 1074.7 and 1079.8 nm Si-like lines of [Fe {\sc XIII}] currently observed
by the Coronal Multi-channel Polarimeter (CoMP). Significant breakthroughs will
be made possible with the new generation of coronagraphs, in three distinct
ways: (i) through single point inversions (which encompasses also the analysis
of MHD wave modes), (ii) using direct comparisons of synthetic MHD or
force-free models with polarization data, and (iii) using tomographic
techniques.Comment: Accepted by Solar Physics, April 201
Properties of the random field Ising model in a transverse magnetic field
We consider the effect of a random longitudinal field on the Ising model in a
transverse magnetic field. For spatial dimension , there is at low
strength of randomness and transverse field, a phase with true long range order
which is destroyed at higher values of the randomness or transverse field. The
properties of the quantum phase transition at zero temperature are controlled
by a fixed point with no quantum fluctuations. This fixed point also controls
the classical finite temperature phase transition in this model. Many critical
properties of the quantum transition are therefore identical to those of the
classical transition. In particular, we argue that the dynamical scaling is
activated, i.e, the logarithm of the diverging time scale rises as a power of
the diverging length scale
Persistence in a Stationary Time-series
We study the persistence in a class of continuous stochastic processes that
are stationary only under integer shifts of time. We show that under certain
conditions, the persistence of such a continuous process reduces to the
persistence of a corresponding discrete sequence obtained from the measurement
of the process only at integer times. We then construct a specific sequence for
which the persistence can be computed even though the sequence is
non-Markovian. We show that this may be considered as a limiting case of
persistence in the diffusion process on a hierarchical lattice.Comment: 8 pages revte
Adaptive cluster expansion for the inverse Ising problem: convergence, algorithm and tests
We present a procedure to solve the inverse Ising problem, that is to find
the interactions between a set of binary variables from the measure of their
equilibrium correlations. The method consists in constructing and selecting
specific clusters of variables, based on their contributions to the
cross-entropy of the Ising model. Small contributions are discarded to avoid
overfitting and to make the computation tractable. The properties of the
cluster expansion and its performances on synthetic data are studied. To make
the implementation easier we give the pseudo-code of the algorithm.Comment: Paper submitted to Journal of Statistical Physic
Spin-Peierls transition in NaV2O5 in high magnetic fields
We investigate the magnetic field dependence of the spin-Peierls transition
in NaVO in the field range 16T-30T. The transition temperature exhibits
a very weak variation with the field, suggesting a novel mechanism for the
formation of the spin-Peierls state. We argue that a charge ordering transition
accompanied by singlet formation is consistent with our observations.Comment: 4 pages, 3 figures, final version to appear in Phys. Rev. B (RC
Female Sex but Not Oestrogen Receptor Expression Predicts Survival in Advanced Gastroesophageal Adenocarcinoma—A Post-hoc Analysis of the GO2 Trial
Gastroesophageal adenocarcinoma is a disease of older adults that is associated with a very poor prognosis. It is less common and has better outcomes in females. The reason for this is unknown but may relate to signalling via the main oestrogen receptors (ER) α and β. In this study, we sought to investigate this using the GO2 clinical trial patient cohort. GO2 recruited older and/or frail patients with advanced gastroesophageal cancer. Immunohistochemistry was performed on tumour samples from 194 patients. The median age of the population was 76 years (range 52–90), and 25.3% were female. Only one (0.5%) tumour sample was positive for ERα, compared to 70.6% for ERβ expression. There was no survival impact according to ERβ expression level. Female sex and younger age were associated with lower ERβ expression. Female sex was also associated with improved overall survival. To our knowledge, this is the largest study worldwide of ER expression in a cohort of patients with advanced gastroesophageal adenocarcinoma. It is also unique, given the age of the population. We have demonstrated that female sex is associated with better survival outcomes with palliative chemotherapy but that this does not appear to be related to ER IHC expression. The differing ER expression according to age supports the concept of a different disease biology with age
The long-time dynamics of two hydrodynamically-coupled swimming cells
Swimming micro-organisms such as bacteria or spermatozoa are typically found
in dense suspensions, and exhibit collective modes of locomotion qualitatively
different from that displayed by isolated cells. In the dilute limit where
fluid-mediated interactions can be treated rigorously, the long-time
hydrodynamics of a collection of cells result from interactions with many other
cells, and as such typically eludes an analytical approach. Here we consider
the only case where such problem can be treated rigorously analytically, namely
when the cells have spatially confined trajectories, such as the spermatozoa of
some marine invertebrates. We consider two spherical cells swimming, when
isolated, with arbitrary circular trajectories, and derive the long-time
kinematics of their relative locomotion. We show that in the dilute limit where
the cells are much further away than their size, and the size of their circular
motion, a separation of time scale occurs between a fast (intrinsic) swimming
time, and a slow time where hydrodynamic interactions lead to change in the
relative position and orientation of the swimmers. We perform a multiple-scale
analysis and derive the effective dynamical system - of dimension two -
describing the long-time behavior of the pair of cells. We show that the system
displays one type of equilibrium, and two types of rotational equilibrium, all
of which are found to be unstable. A detailed mathematical analysis of the
dynamical systems further allows us to show that only two cell-cell behaviors
are possible in the limit of , either the cells are attracted to
each other (possibly monotonically), or they are repelled (possibly
monotonically as well), which we confirm with numerical computations
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