Collège de France

About: Collège de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Dopamine. The organization has 6541 authors who have published 11983 publications receiving 648742 citations. The organization is also known as: College de France.

Na Reactivity toward Carbonate-Based Electrolytes: The Effect of FEC as Additive

Abstract: Authors acknowledge EC for funding through H2020 NAIADES project (LCE10-2014, Contract number 646433), L. Simonin and Y. Chatillon from CEA for sending the Na3V2(PO4)2F3 materials, and members of both the RS2E Na-ion task force and ALISTORE-ERI for fruitful discussions.

On a theorem of Jordan

Abstract: The theorem of Jordan which I want to discuss here dates from 1872. It is an elementary result on finite groups of permutations. I shall first present its translations in Number Theory and Topology. 1. Statements 1.1. Number theory. Let f = ∑n m=0 amx m be a polynomial of degree n, with coefficients in Z. If p is prime, let Np(f) be the number of zeros of f in Fp = Z/pZ. Theorem 1. Assume (i) n ≥ 2, (ii) f is irreducible in Q[x]. Then (a) There are infinitely many p’s with Np(f) = 0. (b) The set P0(f) of p’s with Np(f) = 0 has a density c0 = c0(f) which is > 0. [Recall that a subset P of the set of primes has density c if lim X→∞ number of p ∈ P with p ≤ X π(X) = c, where π(X) is as usual the number of primes ≤ X .] Moreover, Theorem 2. With the notation of Theorem 1, one has c0(f) ≥ 1 n , with strict inequality if n is not a power of a prime. Example. Let f = x + 1. One has p ∈ P0(f) if and only if p ≡ −1 (mod 4); this set is well-known to have density 1/2. We shall see more interesting examples in §5. 1.2. Topology. Let S1 be a circle. Let f : T → S be a finite covering of a topological space S. Assume: (i) f has degree n (i.e. every fiber of f has n elements), with n ≥ 2, (ii) T is arcwise connected and not empty. Theorem 3. There exists a continuous map φ : S1 → S which cannot be lifted to the covering T (i.e. there does not exist any continuous map ψ : S1 → T such that φ = f ◦ ψ). Received by the editors March 1, 2003. 2000 Mathematics Subject Classification. Primary 06-XX, 11-XX, 11F11. This text first appeared in Math Medley 29 (2002), 3–18. The writing was done with the help of Heng Huat Chan. c ©2002 Singapore Mathematical Society. Reprinted with permission.

How do astrocytes shape synaptic transmission? Insights from electrophysiology

Abstract: A major breakthrough in neuroscience has been the realization in the last decades that the dogmatic view of astroglial cells as being merely fostering and buffering elements of the nervous system is simplistic A wealth of investigations now shows that astrocytes actually participate in the control of synaptic transmission in an active manner This was first hinted by the intimate contacts glial processes make with neurons, particularly at the synaptic level, and evidenced using electrophysiological and calcium imaging techniques Calcium imaging has provided critical evidence demonstrating that astrocytic regulation of synaptic efficacy is not a passive phenomenon However, given that cellular activation is not only represented by calcium signaling, it is also crucial to assess concomitant mechanisms We and others have used electrophysiological techniques to simultaneously record neuronal and astrocytic activity, thus enabling the study of multiple ionic currents and in depth investigation of neuro-glial dialogues In the current review, we focus on the input such approach has provided in the understanding of astrocyte-neuron interactions underlying control of synaptic efficacy

Pore fluid chemistry of the North Anatolian Fault Zone in the Sea of Marmara: A diversity of sources and processes

Abstract: As part of the 2007 Marnaut cruise in the Sea of Marmara, an investigation of the pore fluid chemistry of sites along the Main Marmara Fault zone was conducted. The goal was to define the spatial relationship between active faults and fluid outlets and to determine the sources and evolution of the fluids. Sites included basin bounding transtensional faults and strike-slip faults cutting through the topographic highs. The basin pore fluids are dominated by simple mixing of bottom water with a brackish, low-density Pleistocene Lake Marmara end-member that is advecting buoyantly and/or diffusing from a relatively shallow depth. This mix is overprinted by shallow redox reactions and carbonate precipitation. The ridge sites are more complex with evidence for deep-sourced fluids including thermogenic gas and evidence for both silicate and carbonate diagenetic processes. One site on the Western High displayed two mound structures that appear to be chemoherms atop a deep-seated fluid conduit. The fluids being expelled are brines of up to twice seawater salinity with an exotic fluid chemistry extremely high in Li, Sr, and Ba. Oil globules were observed both at the surface and in cores, and type II gas hydrates of thermogenic origin were recovered. Hydrate formation near the seafloor contributes to increase brine concentration but cannot explain their chemical composition, which appears to be influenced by diagenetic reactions at temperatures of 75°C–150°C. Hence, a potential source for fluids at this site is the water associated with the reservoir from which the gas and oil is seeping, which has been shown to be related to the Thrace Basin hydrocarbon system. Our work shows that submerged continental transform plate boundaries can be hydrologically active and exhibit a diversity of sources and processes.