691 research outputs found
Navigating Indigenous Leadership in a Settler Colonial World: Ron and Patricia John 'Come Home' to Stó:lõ Politics
This thesis explores the evolution of Stó:lõ Leadership in the Fraser Valley from the seventies to the nineties, with a focus on Chawathil First Nation (located near Hope, BC). Through a combination of archival and oral history research, I attempt to close the gap in the literature about the post second world war generation of Stó:lõ leaders by analyzing the leadership styles and choices of two leaders from Chawathil First Nation, Patricia and Ron John. While the previous generation of Stó:lõ veterans is well studied, little has been written on Patricia and Ron’s generation, despite their experiencing significant historical events such as the civil rights movements, contemporary assimilation attempts, globalization, the rise of digital technologies, and the Constitution Express. To identify the leadership characteristics of their generation and understand their decision-making process, I analyze Patricia and Ron’s life stories through the lenses of post-colonial theory, ethnohistory, and community-engaged research. The results of this analysis suggest that this generation’s hybridity and continuation of earlier leadership practices, such as the role of task-master of early Stó:lõ leaders (si:yam), enabled them to successfully navigate both the western and the Stó:lõ worlds. From this study a model of Stó:lõ decision-making process emerges in the shape of a Stó:lõ loom, holding key Stó:lõ leadership principles and providing meaning and context to Pat and Ron’s decisions as band manager and Chief of Chawathil First Nation
The Geometry of Uniqueness, Sparsity and Clustering in Penalized Estimation
We provide a necessary and sufficient condition for the uniqueness of
penalized least-squares estimators whose penalty term is given by a norm with a
polytope unit ball, covering a wide range of methods including SLOPE and LASSO,
as well as the related method of basis pursuit. We consider a strong type of
uniqueness that is relevant for statistical problems. The uniqueness condition
is geometric and involves how the row span of the design matrix intersects the
faces of the dual norm unit ball, which for SLOPE is given by the sign
permutahedron. Further considerations based this condition also allow to derive
results on sparsity and clustering features. In particular, we define the
notion of a SLOPE model to describe both sparsity and clustering properties of
this method and also provide a geometric characterization of accessible SLOPE
models.Comment: new title, minor change
Chicken BAFF
Members of the tumor necrosis factor (TNF) family play key roles in the regulation of inflammation, immune responses and tissue homeostasis. Here we describe the identification of the chicken homologue of mammalian B cell activating factor of the TNF family (BAFF/BLyS). By searching a chicken EST database we identified two overlapping cDNA clones that code for the entire open reading frame of chicken BAFF (chBAFF), which contains a predicted transmembrane domain and a putative furin protease cleavage site like its mammalian counterparts. The amino acid identity between soluble chicken and human BAFF is 76%, considerably higher than for most other known cytokines. The chBAFF gene is most strongly expressed in the bursa of Fabricius. Soluble recombinant chBAFF produced by human 293T cells interacted with the mammalian cell-surface receptors TACI, BCMA and BAFF-R. It bound to chicken B cells, but not to other lymphocytes, and it promoted the survival of splenic chicken B cells in culture. Furthermore, bacterially expressed chBAFF induced the selective expansion of B cells in the spleen and cecal tonsils when administered to young chicks. Our results suggest that like its mammalian counterpart, chBAFF plays an important role in survival and/or proliferation of chicken B cells
The Class Of Synthesizable Pseudomeasures
In this paper we study descriptive set theoretic questions related to
concepts of harmonic synthesis on the unit circle T, and their relationship
with the structure of uniqueness sets
La crise de l’humanité européenne selon Patočka
Vielleicht ist der Sinn von Europas Untergang positiv.Jan Patočka « Peut-être le déclin de l’Europe a-t-il un sens positif ». Loin d’être un hapax dissimulé dans un texte secondaire, cette affirmation traverse au contraire toutes les analyses patočkiennes de la crise européenne, devenue, au moment où il écrit, une crise mondiale. C’est pourquoi il ne faudrait pas trop vite conclure à l’européocentrisme de Patočka. D’emblée, il s’agirait de ..
The use HPTLC and Direct Analysis in Real Time-Of-Flight Mass Spectrometry DART-TOF-MS for rapid analysis of degradation by oxidation and sonication of an azo dye
International audienceAdvanced oxidation processes are efficient for the removal of recalcitrant compounds, like azo-dyes. However, the intermediates produced during their degradation can be more toxic than the parent compounds. Improving the knowledge concerning the degradation pathways may be therefore helpful to optimize the process. In this aim, HPTLC and Direct Analysis in Real Time-Of-Flight Mass Spectrometry DART-TOF-MS were considered and applied to analyze the sono-oxidation of an azo dye, methyl red sodium salt (MRSS) as a model compound. Initial and final UV-Vis spectra showed a clear disappearance of the maximum absorption peak, but shows limit since it cannot allow by-products identification. MRSS degradation was confirmed by HPTLC, which also confirmed that MRSS degradation was mainly due to oxidation, while in the considered experimental conditions the sonication effect appeared negligible. Three major peaks were observed by DART-TOF-MS after MRSS oxidation, m/z=139.002, m/z=223.073 and m/z=279.137, Relative abundance of m/z=139.002, which was much higher after oxidation, tends to prove that a large proportion of initial oxydized MRSS was fragmented. The MRSS m/z = 270.078. The coupling of HPTLC and DART-TOF-MS may be subsequently considered to identify the oxidation reaction products
Time-resolved photoelectron and photoion fragmentation spectroscopy study of 9-methyladenine and its hydrates: a contribution to the understanding of the ultrafast radiationless decay of excited DNA bases.
The excited state dynamics of the purine base 9-methyladenine (9Me-Ade) has been investigated by time- and energy-resolved photoelectron imaging spectroscopy and mass-selected ion spectroscopy, in both vacuum and water-cluster environments. The specific probe processes used, namely a careful monitoring of time-resolved photoelectron energy distributions and of photoion fragmentation, together with the excellent temporal resolution achieved, enable us to derive additional information on the nature of the excited states (pp*, np*, ps*, triplet) involved in the electronic relaxation of adenine. The two-step pathway we propose to account for the double exponential decay observed agrees well with recent theoretical calculations. The near-UV photophysics of 9Me-Ade is dominated by the direct excitation of the pp* (1Lb) state (lifetime of 100 fs), followed by internal conversion to the np* state (lifetime in the ps range) via conical intersection. No evidence for the involvement of a ps* or a triplet state was found. 9Me- Ade–(H2O)n clusters have been studied, focusing on the fragmentation of these species after the probe process. A careful analysis of the fragments allowed us to provide evidence for a double exponential decay profile for the hydrates. The very weak second component observed, however, led us to conclude that the photophysics were very different compared with the isolated base, assigned to a competition between (i) a direct one-step decay of the initially excited state (pp* La and/or Lb, stabilised by hydration) to the ground state and (ii) a modified two-step decay scheme, qualitatively comparable to that occurring in the isolated molecule
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The Deployment of Scientific Packages to Asteroid Surfaces
A strategy for the deployment of landers to asteroid surfaces is described. The landing pods are scientific packages with no guidance, navigation and control system, and no specific landing apparatus, so as to minimize onboard platform and maximize payload. The landers are jettisoned from a main spacecraft at high altitude over the target. They impact its surface, bouncing multiple times before finally coming to rest.
The amended gravity field of an asteroid is described in general and regions favorable to a deployment are found close to saddle equilibrium points. For elongated bodies and for binary systems, a linearization shows that a branch of the unstable manifold intersects the surface of the body; the strategy then consists of choosing initial conditions that will express this branch. For quasi-axisymmetric bodies, the initial velocity of the lander is increased to guarantee an impact. The efficacy of the strategy is numerically verified.
A model of the asteroid surface and of the interaction between the pod and this surface is detailed. The asteroid surface is represented with three layers. The asteroid is first modeled using a mesh of triangular facets that can represent its global shape down to the presence of large boulders (greater than 1m). The presence of smaller rocks is accounted for via a stochastic model that generates random collisions with rocks, at impact with the surface or during lasting contact motion (rolling). Finally the interaction with the regolith is handled with a model of contact dynamics, including surface forces and torques (reaction, friction and rolling resistance). The rolling resistance force and torques experienced on regolith are defined and justified. Their coefficients are measured by experiments and explained by theory and finite-element simulations.
Practical mission case studies are presented and discussed, for asteroid Itokawa, 1999 JU3, 1999 KW4 Alpha and Beta
Soil to Sail - Asteroid Landers on Near-Term Sailcraft as an Evolution of the GOSSAMER Small Spacecraft Solar Sail Concept for In-Situ Characterization
Any effort which intends to physically interact with specific asteroids requires understanding at least of the composition and multi-scale structure of the surface layers, sometimes also of the interior. Therefore, it is necessary first to characterize each target object sufficiently by a precursor mission to design the mission which then interacts with the object. In small solar system body (SSSB) science missions, this trend towards landing and sample-return missions is most apparent. It also has led to much interest in MASCOT-like landing modules and instrument carriers. They integrate at the instrument level to their mothership and by their size are compatible even with small interplanetary missions.
The DLR-ESTEC GOSSAMER Roadmap NEA Science Working Groups‘ studies identified Multiple NEA Rendezvous (MNR) as one of the space science missions only feasible with solar sail propulsion. The parallel Solar Polar Orbiter (SPO) study showed the ability to access any inclination and a wide range of heliocentric distances. It used a separable payload module conducting the SPO mission after delivery by sail to the proper orbit. The Displaced L1 (DL1), spaceweather early warning mission study, outlined a very lightweight sailcraft operating close to Earth, where all objects of interest to planetary defence must pass.
These and many other studies outline the unique capability of solar sails to provide access to all SSSB, at least within the orbit of Jupiter. Since the original MNR study, significant progress has been made to explore the performance envelope of near-term solar sails for multiple NEA rendezvous.
However, although it is comparatively easy for solar sails to reach and rendezvous with objects in any inclination and in the complete range of semi-major axis and eccentricity relevant to NEOs and PHOs, it remains notoriously difficult for sailcraft to interact physically with a SSSB target object as e.g. the HAYABUSA missions do.
The German Aerospace Center, DLR, recently brought the GOSSAMER solar sail deployment technology to qualification status in the GOSSAMER-1 project and continues the development of closely related technologies for very large deployable membrane-based photovoltaic arrays in the GOSOLAR project, on which we report separately.
We expand the philosophy of the GOSSAMER solar sail concept of efficient multiple sub-spacecraft integration to also include landers for one-way in-situ investigations and sample-return missions. These are equally useful for planetary defence scenarios, SSSB science and NEO utilization. We outline the technological concept used to complete such missions and the synergetic integration and operation of sail and lander.
We similarly extend the philosophy of MASCOT and use its characteristic features as well as the concept of Constraints-Driven Engineering for a wider range of operations. For example, the MASCOT Mobility hopping mechanism has already been adapted to the specific needs of MASCOT2. Utilizing sensors as well as predictions, those actuators could in a further development be used to implement anti-bouncing control schemes, by counteracting with the lander‘s rotation. Furthermore by introducing sudden jerk into the lander by utilization of the mobility, layers of loose regolith can be swirled up for sampling
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