112 research outputs found
A new early Silurian prioniodontid conodont with three P elements from Iran and associated species
Copyright © 2015 P. MÀnnik et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article
Lâinfluence de la glaciation du Gondwana Ă lâOrdovicien supĂ©rieur et au Silurien de la Baltique. Un test de la cyclicitĂ© de lâenvironnement Ă lâaide des isotopes du carbone
étudié et trois autres au Llandovérien et au commencement du Wenlock. Les nouvelles données de Hamoumi [1999] déplacent
le dĂ©but de lâĂ©poque glaciale au Caradocien infĂ©rieur quand la mer Baltique passe des moyennes aux basses latitudes
de lâhĂ©misphĂšre austral [Torsvik et al., 1996]. En mĂȘme temps le centre de la glaciation se dĂ©place du nord de
lâAfrique au sud de lâAmĂ©rique.
Malgré la distance considérable entre les régions polaires de Gondwana et les régions subtropicales de la mer Baltique,
tous les Ă©vĂ©nements glaciaires susnommĂ©s sont dâune certaine maniĂšre reflĂ©tĂ©s en mer Baltique de lâest. Le mĂ©canisme
de cette influence est discutable dans le détail mais, les processus climatiques et océaniques jouent un rÎle
essentiel. Il est généralement admis que les glaciations sont marquées par les excursions positives de valeurs de Ύ18
O et
ÎŽ13
C provoquĂ©es par lâaugmentation de la couche de glace aux rĂ©gions polaires, la bioproduction, le dĂ©placement du carbone
organique dans les sĂ©diments et le refroidissement de lâocĂ©an.
Les relations connues entre ces différents facteurs permettent de corréler les événements glaciaires de Gondwana
avec les changements simultanés de la courbe des isotopes fixée en mer Baltique. Par ailleurs, le modÚle du cycle des
isotopes du carbone océanique de Jeppsonn [1990] est mis en perspective avec les valeurs réelles mesurées.
Les excursions positives de ÎŽ13
C (les valeurs maximum entre parenthÚses) sont évaluées pour la Baltique : le Caradocien
moyen (2,2 â°), lâAshgill infĂ©rieur (2,5 â°), lâHirnantien (6 â°), lâAĂ©ronien infĂ©rieur (3,7 â°), le Telychien infĂ©rieur
(2,7 â°), le Wenlock infĂ©rieur (5,2 â°). Les changements pour la plupart sont en corrĂ©lation avec les baisses du
niveau de lâocĂ©an, ayant Ă©videmment un caractĂšre glacio-eustatique. La corrĂ©lation positive se trouve aussi entre la glaciation
et les changements de la biodiversitĂ© largement connus comme la crise Oandu (au Caradocien), lâextinction en
masse de Hirnantia et lâĂ©vĂ©nement Ireviken au Wenlock.
Les données analysées permettent de conclure que : (1) les quatre glaciations du Gondwana identifiées notamment
sur la base de tillites et dâargiles microconglomĂ©ratiques et biostratigraphiquement datĂ©es sont dans les profils baltiques clairement marquĂ©s par lâexcursion de la courbe des isotopes du carbone ; (2) trois anomalies positives mineures
Ă lâAshgill et au Caradoc ainsi que des donnĂ©es sur lâabondance spĂ©cifique des algues, indiquent la prĂ©sence dâune pĂ©riode
climatique plus froide Ă lâOrdovicien infĂ©rieur. Ces donnĂ©es sont en faveur dâun dĂ©but plus prĂ©coce de la glaciation
du Gondwana, mais des datations nouvelles des roches glaciogéniques considérées sont nécessaires pour le
confirmer ; (3) le test du modĂ©le ocĂ©anologique de Jeppsson Ă lâaide des isotopes du carbone a souvent montrĂ© des contradictions
entre le modÚle établi et les valeurs mesurées ; (4) on ne devrait pas représenter les épisodes climatiques-
ocĂ©aniques seulement sur la base de la distribution dâun petit nombre dâespĂšces de conodontes connus mais aussi Ă
lâaide de marqueurs mettant en Ă©vidence les changements plus gĂ©nĂ©raux du milieu marin fondĂ©s sur les critĂšres lithologiques,
géochimiques ou/et paléontologiques
Rf-induced transport of Cooper pairs in superconducting single electron transistors in a dissipative environment
We investigate low-temperature and low-voltage-bias charge transport in a
superconducting Al single electron transistor in a dissipating environment,
realized as on-chip high-ohmic Cr microstrips. In our samples with relatively
large charging energy values Ec > EJ, where EJ is the energy of the Josephson
coupling, two transport mechanisms were found to be dominating, both based on
discrete tunneling of individual Cooper pairs: Depending on the gate voltage
Vg, either sequential tunneling of pairs via the transistor island (in the open
state of the transistor around the points Qg = CgVg = e mod(2e), where Cg is
the gate capacitance) or their cotunneling through the transistor (for Qg away
of these points) was found to prevail in the net current. As the open states of
our transistors had been found to be unstable with respect to quasiparticle
poisoning, high-frequency gate cycling (at f ~ 1 MHz) was applied to study the
sequential tunneling mechanism. A simple model based on the master equation was
found to be in a good agreement with the experimental data.Comment: 8 pages, 6 figure
Capacitively Enhanced Thermal Escape in Underdamped Josephson Junctions
We have studied experimentally the escape dynamics in underdamped
capacitively shunted and unshunted Josephson junctions with submicroampere
critical currents below 0.5 K temperatures. In the shunted junctions, thermal
activation process was preserved up to the highest temperature where the escape
in the unshunted junctions exhibits the phase diffusion. Our observations in
the shunted junctions are in good agreement with the standard thermal
activation escape, unlike the results in the unshunted junctions.Comment: 4 pages, 3 figure
Protein Pattern Formation
Protein pattern formation is essential for the spatial organization of many
intracellular processes like cell division, flagellum positioning, and
chemotaxis. A prominent example of intracellular patterns are the oscillatory
pole-to-pole oscillations of Min proteins in \textit{E. coli} whose biological
function is to ensure precise cell division. Cell polarization, a prerequisite
for processes such as stem cell differentiation and cell polarity in yeast, is
also mediated by a diffusion-reaction process. More generally, these functional
modules of cells serve as model systems for self-organization, one of the core
principles of life. Under which conditions spatio-temporal patterns emerge, and
how these patterns are regulated by biochemical and geometrical factors are
major aspects of current research. Here we review recent theoretical and
experimental advances in the field of intracellular pattern formation, focusing
on general design principles and fundamental physical mechanisms.Comment: 17 pages, 14 figures, review articl
The Number of Genomic Copies at the 16p11.2 Locus Modulates Language, Verbal Memory, and Inhibition.
Deletions and duplications of the 16p11.2 BP4-BP5 locus are prevalent copy number variations (CNVs), highly associated with autism spectrum disorder and schizophrenia. Beyond language and global cognition, neuropsychological assessments of these two CNVs have not yet been reported.
This study investigates the relationship between the number of genomic copies at the 16p11.2 locus and cognitive domains assessed in 62 deletion carriers, 44 duplication carriers, and 71 intrafamilial control subjects.
IQ is decreased in deletion and duplication carriers, but we demonstrate contrasting cognitive profiles in these reciprocal CNVs. Deletion carriers present with severe impairments of phonology and of inhibition skills beyond what is expected for their IQ level. In contrast, for verbal memory and phonology, the data may suggest that duplication carriers outperform intrafamilial control subjects with the same IQ level. This finding is reminiscent of special isolated skills as well as contrasting language performance observed in autism spectrum disorder. Some domains, such as visuospatial and working memory, are unaffected by the 16p11.2 locus beyond the effect of decreased IQ. Neuroimaging analyses reveal that measures of inhibition covary with neuroanatomic structures previously identified as sensitive to 16p11.2 CNVs.
The simultaneous study of reciprocal CNVs suggests that the 16p11.2 genomic locus modulates specific cognitive skills according to the number of genomic copies. Further research is warranted to replicate these findings and elucidate the molecular mechanisms modulating these cognitive performances
HybriFree: a robust and rapid method for the development of monoclonal antibodies from different host species
First documentation of the Polygnathoides siluricus conodont Zone (Ludfordian) in South America (Argentina) and the stratigraphic significance of the younger species of Kockelella (Conodonta)
The coquinoid beds from the middle part of the Los Espejos Formation at the Poblete creek section (Talacasto Creek) yielded abundant conodonts. The genus Kockelella (Walliser) represents the most relevant biostratigraphical genus in this conodont fauna. The co-occurrence of Kockelella maenniki Serpagli and Corradini, Kockelella variabilis ichnusae Serpagli and Corradini, K. variabilis Walliser, Kockelella ortus sardoa (Serpagli & Corradini), and Kockelella ortus absidata (Barrick & Klapper) allow us to record for the first time the Polygnathoides siluricus Zone in South America, which suggests the Ludfordian Stage (late Ludlow). We also propose an accurate correlation of the Los Espejos Formation with the lower Ludfordian deposits from the Carnic Alps, Sardinia, Morocco, Czech Republic, Gotland, and North America.Fil: Gomez, Maria Jose. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas FĂsicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Mestre, Ana Paula. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas FĂsicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Garcias Paez, Yanina Vanesa. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - San Juan. Centro de Investigaciones de la Geosfera y Biosfera. Universidad Nacional de San Juan. Facultad de Ciencias Exactas FĂsicas y Naturales. Centro de Investigaciones de la Geosfera y Biosfera; ArgentinaFil: Corradini, Carlo. UniversitĂ degli Studi di Cagliari; Itali
A genome-wide association study of anorexia nervosa.
Anorexia nervosa (AN) is a complex and heritable eating disorder characterized by dangerously low body weight. Neither candidate gene studies nor an initial genome-wide association study (GWAS) have yielded significant and replicated results. We performed a GWAS in 2907 cases with AN from 14 countries (15 sites) and 14â860 ancestrally matched controls as part of the Genetic Consortium for AN (GCAN) and the Wellcome Trust Case Control Consortium 3 (WTCCC3). Individual association analyses were conducted in each stratum and meta-analyzed across all 15 discovery data sets. Seventy-six (72 independent) single nucleotide polymorphisms were taken forward for in silico (two data sets) or de novo (13 data sets) replication genotyping in 2677 independent AN cases and 8629 European ancestry controls along with 458 AN cases and 421 controls from Japan. The final global meta-analysis across discovery and replication data sets comprised 5551 AN cases and 21â080 controls. AN subtype analyses (1606 AN restricting; 1445 AN binge-purge) were performed. No findings reached genome-wide significance. Two intronic variants were suggestively associated: rs9839776 (P=3.01 Ă 10(-7)) in SOX2OT and rs17030795 (P=5.84 Ă 10(-6)) in PPP3CA. Two additional signals were specific to Europeans: rs1523921 (P=5.76 Ă 10(-)(6)) between CUL3 and FAM124B and rs1886797 (P=8.05 Ă 10(-)(6)) near SPATA13. Comparing discovery with replication results, 76% of the effects were in the same direction, an observation highly unlikely to be due to chance (P=4 Ă 10(-6)), strongly suggesting that true findings exist but our sample, the largest yet reported, was underpowered for their detection. The accrual of large genotyped AN case-control samples should be an immediate priority for the field
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