453 research outputs found
Les espaces de l'halieutique
L'Ă©tang de Thau est un espace lagunaire semi fermĂ© dont les communications avec la mer sont limitĂ©es. L'exploitation de la palourde, ressource intrinsĂšquement peu mobile, est au coeur de l'activitĂ© de pĂȘche dans cet Ă©tang. Il semble donc, a priori, que les notions d'espace mis en oeuvre par l'exploitation de cette ressource prĂ©sentent un caractĂšre de proximitĂ© et une dimension localisĂ©e Ă l'Ă©cosystĂšme "Ă©tang de Thau". DĂšs lors, on pourrait penser que la connaissance Ă©cologique de ce milieu - oĂč d'importants programmes scientifiques ont Ă©tĂ© rĂ©alisĂ©es -, alliĂ©e Ă la faible mobilitĂ© de cette population de bivalves fouisseurs, constituent des conditions favorables Ă une gestion "efficace" de cet Ă©cosystĂšme. Ce sentiment est renforcĂ© par le contexte social dans lequel Ă©voluent les communautĂ©s de pĂȘcheurs qui ont derriĂšre elles une longue pratique de la gestion (prud'homies). Or, aprĂšs une pĂ©riode florissante achevĂ©e en 1992, cette pĂȘcherie traverse une crise aiguĂ«. Les professionnels constatent en effect une forte diminution des stocks qui se traduit par (i) une rĂ©gression des quantitĂ©s pĂȘchĂ©es par jours de travail (PUE) (ii) une diminution des prix (contre toute logique de marchĂ©) et (iii) une dĂ©croissance du nombre de pĂȘcheurs. ParallĂšlement on observe une transformation des mĂ©thodes de pĂȘche avec la gĂ©nĂ©ralisation de la pĂȘche en plongĂ©e aux dĂ©pens de "l'arseliĂšre" technique traditionnelle qui a quasiment disparu. Dans ce contexte, et Ă la demande de la profesison, un programme pluridisciplinaire (programme Palourde) a Ă©tĂ© mis en oeuvre afin d'identifier les limites du systĂšme actuel puis d'Ă©laborer un nouveau systĂšme de gestion. Ce travail a Ă©tĂ© menĂ© selon une dĂ©marche de concertation Ă©largie de l'ensemble des partenaires de l'exploitation (pĂȘcheurs, mareyeurs, gestionnaires) et de façon nĂ©gociĂ©e entre les acteurs... (RĂ©sumĂ© d'auteur
Livestock and Local Development: Going to a New Humananimal Relationship
Along the past ten years, the French National Agency for Research (ANR) has financed projects regarding livestock. Results of five projects were gathered to understand the long-term livestock trends. At the end of the 19th century, animal breeding was oriented towards the production of goods to meet the local, regional, national and global demand, according to the zone. The market gradually became the key-factor to norm both production and consumption. It is now integrating environmental norms and is starting to invest in the social domain. However, this economical vision of animal production does not take into account the other functions of livestock, from âfarm forkâ to âtable forkâ. So, in parallel to the multi-functionality of livestock at the farm level, which is mentioned by several authors, livestock has a significant role at the local scale. Furthermore, in the past four decades, animal production sector has known several serious scandals with severe consequences in human health. At the same time, the FAO scoop in 2006 about the significant environmental impact of animal breeding has chocked a large part of the human society. Hence, in parallel to the discredit of animal production towards the consumers, these successive crises have led a part of the local and global society to question the human-animal relationship. In this way, a large part of the urban population with no contact with the rural world, would easily believe in animal welfare, and break the supply chain leading to the slaughterhouse. And to confirm this trend, research institutes are already seeking alternatives to meat and animal proteins. Consequently, maybe it is time now to think imagine other farming systems based on other human-animal relationships and other environment-society interactions; and perhaps to establish an adequate set of policies to strengthen this perspective
Explaining diversity of livestock-farming management strategies of multiple-job holders: importance of level of production objectives and role of farming in the household
LRP-1 Promotes Cancer Cell Invasion by Supporting ERK and Inhibiting JNK Signaling Pathways
Background: The low-density lipoprotein receptor-related protein-1 (LRP-1) is an endocytic receptor mediating the clearance of various extracellular molecules involved in the dissemination of cancer cells. LRP-1 thus appeared as an attractive receptor for targeting the invasive behavior of malignant cells. However, recent results suggest that LRP-1 may facilitate the development and growth of cancer metastases in vivo, but the precise contribution of the receptor during cancer progression remains to be elucidated. The lack of mechanistic insights into the intracellular signaling networks downstream of LRP-1 has prevented the understanding of its contribution towards cancer.
Methodology/Principal Findings: Through a short-hairpin RNA-mediated silencing approach, we identified LRP-1 as a main regulator of ERK and JNK signaling in a tumor cell context. Co-immunoprecipitation experiments revealed that LRP-1 constitutes an intracellular docking site for MAPK containing complexes. By using pharmacological agents, constitutively active and dominant-negative kinases, we demonstrated that LRP-1 maintains malignant cells in an adhesive state that is favorable for invasion by activating ERK and inhibiting JNK. We further demonstrated that the LRP-1-dependent regulation of MAPK signaling organizes the cytoskeletal architecture and mediates adhesive complex turnover in cancer cells. Moreover, we found that LRP-1 is tethered to the actin network and to focal adhesion sites and controls ERK and JNK targeting to talin-rich structures.
Conclusions: We identified ERK and JNK as the main molecular relays by which LRP-1 regulates focal adhesion disassembly of malignant cells to support invasion
Adverse childhood experiences and premature all-cause mortality
Events causing stress responses during sensitive periods of rapid neurological development in childhood may be early determinants of all-cause premature mortality. Using a British birth cohort study of individuals born in 1958, the relationship between adverse childhood experiences (ACE) and mortality â€50 year was examined for men (n = 7,816) and women (n = 7,405) separately. ACE were measured using prospectively collected reports from parents and the school: no adversities (70 %); one adversity (22 %), two or more adversities (8 %). A Cox regression model was carried out controlling for early life variables and for characteristics at 23 years. In men the risk of death was 57 % higher among those who had experienced 2+ ACE compared to those with none (HR 1.57, 95 % CI 1.13, 2.18, p = 0.007). In women, a graded relationship was observed between ACE and mortality, the risk increasing as ACE accumulated. Women with one ACE had a 66 % increased risk of death (HR 1.66, 95 % CI 1.19, 2.33, p = 0.003) and those with â„2 ACE had an 80 % increased risk (HR 1.80, 95 % CI 1.10, 2.95, p = 0.020) versus those with no ACE. Given the small impact of adult life style factors on the association between ACE and premature mortality, biological embedding during sensitive periods in early development is a plausible explanatory mechanism
Artificial reefs: from ecological processes to fishing enhancement tools
info:eu-repo/semantics/publishedVersio
From error bounds to the complexity of first-order descent methods for convex functions
This paper shows that error bounds can be used as effective tools for
deriving complexity results for first-order descent methods in convex
minimization. In a first stage, this objective led us to revisit the interplay
between error bounds and the Kurdyka-\L ojasiewicz (KL) inequality. One can
show the equivalence between the two concepts for convex functions having a
moderately flat profile near the set of minimizers (as those of functions with
H\"olderian growth). A counterexample shows that the equivalence is no longer
true for extremely flat functions. This fact reveals the relevance of an
approach based on KL inequality. In a second stage, we show how KL inequalities
can in turn be employed to compute new complexity bounds for a wealth of
descent methods for convex problems. Our approach is completely original and
makes use of a one-dimensional worst-case proximal sequence in the spirit of
the famous majorant method of Kantorovich. Our result applies to a very simple
abstract scheme that covers a wide class of descent methods. As a byproduct of
our study, we also provide new results for the globalization of KL inequalities
in the convex framework.
Our main results inaugurate a simple methodology: derive an error bound,
compute the desingularizing function whenever possible, identify essential
constants in the descent method and finally compute the complexity using the
one-dimensional worst case proximal sequence. Our method is illustrated through
projection methods for feasibility problems, and through the famous iterative
shrinkage thresholding algorithm (ISTA), for which we show that the complexity
bound is of the form where the constituents of the bound only depend
on error bound constants obtained for an arbitrary least squares objective with
regularization
THUMP from archaeal tRNA:m(2)(2)G10 methyltransferase, a genuine autonomously folding domain
The tRNA:m(2)(2)G10 methyltransferase of Pyrococus abyssi (PAB1283, a member of COG1041) catalyzes the N(2),N(2)-dimethylation of guanosine at position 10 in tRNA. Boundaries of its THUMP (THioUridine synthases, RNA Methyltransferases and Pseudo-uridine synthases)âcontaining N-terminal domain [1â152] and C-terminal catalytic domain [157â329] were assessed by trypsin limited proteolysis. An inter-domain flexible region of at least six residues was revealed. The N-terminal domain was then produced as a standalone protein (THUMPα) and further characterized. This autonomously folded unit exhibits very low affinity for tRNA. Using protein fold-recognition (FR) methods, we identified the similarity between THUMPα and a putative RNA-recognition module observed in the crystal structure of another THUMP-containing protein (ThiI thiolase of Bacillus anthracis). A comparative model of THUMPα structure was generated, which fulfills experimentally defined restraints, i.e. chemical modification of surface exposed residues assessed by mass spectrometry, and identification of an intramolecular disulfide bridge. A model of the whole PAB1283 enzyme docked onto its tRNA(Asp) substrate suggests that the THUMP module specifically takes support on the co-axially stacked helices of T-arm and acceptor stem of tRNA and, together with the catalytic domain, screw-clamp structured tRNA. We propose that this mode of interactions may be common to other THUMP-containing enzymes that specifically modify nucleotides in the 3D-core of tRNA
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