Search results for "FOS"
showing 10 items of 15075 documents
First fossil record (Middle Miocene) of the viper shark Trigonognathus Mochizuki and Ohe, 1990, in the Mediterranean realm
2022
The genus Trigonognathus Mochizuki and Ohe, 1990, is a monospecific taxon of `lantern sharks¿ (i.e., family Etmopteridae), a group of small-sized bioluminescent deep-sea chondrichthyans, ranging in mature male specimens between 42¿47 cm total length, and at least 52 cm for females (Ebert et al., 2021). This shark inhabits the upper continental slopes as well as the uppermost slope of seamounts, often at the bottom, at depths ranging between 250¿1000 m, but has been caught at 150 m and 270 m in deep open waters (Mochizuki and Ohe, 1990; Compagno et al., 2005; Ebert et al., 2021). Only two species have been described thus far, the extant species Trigonognathus kabeyai Mochizuki and Ohe, 1990,…
Smithian (Early Triassic) ammonoid faunas from northwestern Guangxi (South China): Taxonomy and Biochronology.
2008
184 pages; International audience; The highly fossiliferous succession of Smithian (Early Triassic) ammonoids from northwestern Guangxi (South China) provides a key equatorial record, at the boundary between Tethys and Panthalassa. After the end-Permian extinction, ammonoids reached their first major diversity peak during Smithian times, coupled with a marked contrast in their latitudinal distribution. This monograph contains a part of the fundamental taxonomic and biostratigraphic data of a more comprehensive research project addressing patterns of recovery in time and space of Early Triassic ammonoids and other marine clades, in conjunction with global paleoceanographic and paleoclimatic …
New Smithian (Early Triassic) ammonoids from Crittenden Springs, Elko County, Nevada: implications for taxonomy, biostratigraphy and biogeography.
2010
41 pages; International audience
Historical biogeography of Melastomataceae: the roles of Tertiary migration and long-distance dispersal
2001
Melastomataceae and Memecylaceae are pantropically distributed sister groups for which an ndhF gene phylogeny for 91 species in 59 genera is here linked with Eurasian and North American fossils in a molecular clock approach to biogeographical reconstruction. Nine species from the eight next-closest families are used to root phylogenetic trees obtained under maximum likelihood criteria. Melastomataceae comprise â¼3000 species in the neotropics, â¼1000 in tropical Asia, 240 in Africa, and 225 in Madagascar in 150-166 genera, and the taxa sampled come from throughout this geographic range. Based on fossils, ranges of closest relatives, tree topology, and calibrated molecular divergences, Mel…
Transition densities for strongly degenerate time inhomogeneous random models
2013
In this paper we study the existence of densities for strongly degenerate stochastic differential equations whose coefficients depend on time and are not globally Lipschitz. In these models neither local ellipticity nor the strong H\"ormander condition is satisfied. In this general setting we show that continuous transition densities indeed exist in all neighborhoods of points where the weak H\"ormander condition is satisfied. We also exhibit regions where these densities remain positive. We then apply these results to stochastic Hodgkin-Huxley models as a first step towards the study of ergodicity properties of such systems.
Supplemental Material for Lemopoulos et al., 2019
2019
Beagle file for the ANGSD pipeline. Genotype probabilities of 116 brown trout. 7520 SNPs are identified and mapped to corresponding location in the Atlantic salmon genome.
Collective vs. individual behaviour for sums of i.i.d. random variables: appearance of the one-big-jump phenomenon
2023
This article studies large and local large deviations for sums of i.i.d. real-valued random variables in the domain of attraction of an $\alpha$-stable law, $\alpha\in (0,2]$, with emphasis on the case $\alpha=2$. There are two different scenarios: either the deviation is realised via a collective behaviour with all summands contributing to the deviation (a Gaussian scenario), or a single summand is atypically large and contributes to the deviation (a one-big-jump scenario). Such results are known when $\alpha \in (0,2)$ (large deviations always follow a one big-jump scenario) or when the random variables admit a moment of order $2+\delta$ for some $\delta>0$. We extend these results, inclu…
Non-autonomous rough semilinear PDEs and the multiplicative Sewing Lemma
2021
We investigate existence, uniqueness and regularity for local solutions of rough parabolic equations with subcritical noise of the form $du_t- L_tu_tdt= N(u_t)dt + \sum_{i = 1}^dF_i(u_t)d\mathbf X^i_t$ where $(L_t)_{t\in[0,T]}$ is a time-dependent family of unbounded operators acting on some scale of Banach spaces, while $\mathbf X\equiv(X,\mathbb X)$ is a two-step (non-necessarily geometric) rough path of H\"older regularity $\gamma >1/3.$ Besides dealing with non-autonomous evolution equations, our results also allow for unbounded operations in the noise term (up to some critical loss of regularity depending on that of the rough path $\mathbf X$). As a technical tool, we introduce a versi…
On First-Passage-Time Densities for Certain Symmetric Markov Chains
2004
The spatial symmetry property of truncated birth-death processes studied in Di Crescenzo [6] is extended to a wider family of continuous-time Markov chains. We show that it yields simple expressions for first-passage-time densities and avoiding transition probabilities, and apply it to a bilateral birth-death process with jumps. It is finally proved that this symmetry property is preserved within the family of strongly similar Markov chains.
Rough McKean-Vlasov dynamics for robust ensemble Kalman filtering
2021
Motivated by the challenge of incorporating data into misspecified and multiscale dynamical models, we study a McKean-Vlasov equation that contains the data stream as a common driving rough path. This setting allows us to prove well-posedness as well as continuity with respect to the driver in an appropriate rough-path topology. The latter property is key in our subsequent development of a robust data assimilation methodology: We establish propagation of chaos for the associated interacting particle system, which in turn is suggestive of a numerical scheme that can be viewed as an extension of the ensemble Kalman filter to a rough-path framework. Finally, we discuss a data-driven method bas…