Microelectrode records from a cockroach thoracic ganglion: Synaptic potentials and temporal patterns of spike activity

1. 1. E.p.s.p.s and i.p.s.p.s + were recorded from cells in the cockroach third thoracic ganglion, using microcapillary electrodes filled with 3 M KCl.2. 2. Spike response patterns indicating complex integrative activities at the single cell level were also recorded.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32924/1/0000306.pd

Paleoenvironments, δ13C and δ18O signatures in the Neoproterozoic carbonates of the Comba Basin, Republic of Congo: Implications for regional correlations and Marinoan event

The Ediacaran Schisto-Calcaire Group is a similar to 1300 m-thick succession belonging to the West Congo Supergroup in Central Africa. In the Comba Basin, it consists of three carbonate-dominated units defined as formations (SCI to SCIII) that are unconformably overlain by clastic deposits (Mpioka Group) interpreted as a molassic formation associated with the Panafrican Orogen. The underlying Upper Tillite and Cap Carbonate (SCIa) units, considered as markers of the Snowball Earth event were studied in three sections. We investigated the carbonates of the Schisto-Calcaire Group by defining new microfacies (MF1-MF7) and we performed C and O isotopic analyses in order to constraint the depositional and diagenetic events directly after the Marinoan interval. Stratigraphic variations of the stable isotopes are important in the series with lighter delta O-18 values (>1.5 parts per thousand) than those of the Neoproterozoic ocean in the SCIc unit. According to regional stratigraphy a temperature effect can be dismissed and a freshwater surface layer is the origin of such negative delta O-18 values in this unit. The negative delta C-13 anomaly (-3.5 parts per thousand on average) of the Cap Carbonate is similarly to the delta O-18 values (-6.4 parts per thousand on average) in the range of the marine domain during postglacial sea level rise. The sample suite as a whole (SCII and SCIII formations) displays heavier delta O-18 and delta C-13 than those of the lower part (SCI unit) of the Schisto-Calcaire Group. The comparison with the Lower Congo (Democratic Republic of Congo) and Nyanga (Gabon) basins shows that the meteoric flushing in SCIc unit of the Schisto-Calcaire Group was regional and not local, and could be derived from a climatic evolution. Although an overall overprint is present, our isotopic relationships argue against overall diagenetic resetting of primary compositions and suggest that with careful examination combined with detailed petrographic analysis general depositional and diagenetic controls can be discerned in oxygen and carbon isotopic data in the Schisto-Calcaire Group

Is Cerebroplacental Ratio A Marker of Impaired Fetal Growth Velocity and Adverse Pregnancy Outcome?

BACKGROUND: The cerebroplacental ratio has been proposed as a marker of failure to reach growth potential near term. Low cerebroplacental ratio, regardless of the fetal size, is independently associated with the need for operative delivery for presumed fetal compromise and with neonatal unit admission at term. OBJECTIVE: The main aim of this study was to evaluate whether the cerebroplacental ratio at term is a marker of reduced fetal growth rate. The secondary aim was to investigate the relationship between low cerebroplacental ratio at term, reduced fetal growth velocity and adverse pregnancy outcome. DESIGN: retrospective cohort study of singleton pregnancies in a tertiary referral center. The abdominal circumference was measured at 20-24 weeks' gestation, and both abdominal circumference and fetal Dopplers recorded at or beyond 35 weeks, within two weeks of delivery. Abdominal circumference and birthweight values were converted into Z scores and centiles, respectively, and fetal Doppler parameters into multiples of median, adjusting for gestational age. Abdominal circumference growth velocity was quantified using the difference in abdominal circumference Z score, comparing the scan at or beyond 35 weeks with the scan at 20-24 weeks. Both univariable and multivariable logistic regression analyses were performed to investigate the association between low cerebroplacental ratio, low abdominal circumference growth velocity (in the lowest decile), and to identify and adjust for potential confounders. As a sensitivity analysis, we refitted the model excluding the data on pregnancies with small for gestational age neonates. RESULTS: The study included 7944 pregnancies. Low cerebroplacental ratio multiples of median was significantly associated with both low abdominal circumference growth velocity (adjusted OR 2.10; 95%CI 1.71-2.57, p<0.001) and small for gestational age (adjusted OR 3.60; 95%CI 3.04-4.25, p<0.001). After the exclusion of pregnancies resulting in small for gestational age neonates, low cerebroplacental ratio multiples of median remained significantly associated with both low abdominal circumference growth velocity (adjusted OR 1.76; 95%CI 1.34-2.30, p<0.001) and birthweight centile (adjusted OR 0.99; 95%CI 0.998-0.995, p<0.001). The need for operative delivery for fetal compromise was significantly associated with low cerebroplacental ratio (adjusted OR 1.40; 95%CI 1.10-1.78, p=0.006), even after adjusting for both the umbilical artery pulsatility index multiples of median and middle cerebral artery pulsatility index multiples of median. The results were similar even after the exclusion of pregnancies resulting in small for gestational age neonates (adjusted OR 1.39; 95%CI 1.06-1.84, p=0.018). Low cerebroplacental ratio multiples of median remained significantly associated with the risk of operative delivery for presumed fetal compromise (p<0.001), even after adjusting for the known antenatal and intrapartum risk factors. These associations persisted even after exclusion of small for gestational age births. In appropriate for gestational age sized fetuses, abdominal circumference growth velocity was significantly lower in those with low cerebroplacental ratio multiples of median than in those with normal cerebroplacental ratio multiples of median (p<0.001). CONCLUSION: Cerebroplacental ratio is a marker of impaired fetal growth velocity and adverse pregnancy outcome, even in fetuses whose size is considered appropriate using conventional biometry

Optical Properties of GaSb Nanofibers

Amorphous GaSb nanofibers were obtained by ion beam irradiation of bulk GaSb single-crystal wafers, resulting in fibers with diameters of ~20 nm. The Raman spectra and photoluminescence (PL) of the ion irradiation-induced nanofibers before and after annealing were studied. Results show that the Raman intensity of the GaSb LO phonon mode decreased after ion beam irradiation as a result of the formation of the amorphous nanofibers. A new mode is observed at ~155 cm-1 both from the unannealed and annealed GaSb nanofiber samples related to the A1g mode of Sb–Sb bond vibration. Room temperature PL measurements of the annealed nanofibers present a wide feature band at ~1.4–1.6 eV. The room temperature PL properties of the irradiated samples presents a large blue shift compared to bulk GaSb. Annealed nanofibers and annealed nanofibers with Au nanodots present two different PL peaks (400 and 540 nm), both of which may originate from Ga or O vacancies in GaO. The enhanced PL and new band characteristics in nanostructured GaSb suggest that the nanostructured fibers may have unique applications in optoelectronic devices

Sedimentary architecture of detached deep-marine canyons: Examples from the East Coast Basin of New Zealand

Submarine canyons are conduits for the distribution of sediment across continental margins. Although many canyons connect directly with fluvial or marine littoral system feeders, canyons detached from direct hinterland supply are also recognized. The fill of detached canyons remains enigmatic, because their deep-water setting restricts analysis of their evolution and stratigraphic architecture. Therefore, this study aims to investigate the sedimentary processes that infilled deep-water canyons and the resulting architecture. Miocene outcrops of an exhumed deep-water system from the East Coast Basin, New Zealand are documented and compared with the morphology and seismic scale architecture of a modern detached canyon system on the same convergent margin. The outcropping system preserves the downstream margin of a sub-basin deposited at palaeo-water depths >700 m. A 6 km wide by 430 m deep incision is filled by heterogeneous siliciclastic sediments, 50% of which comprise graded thin-beds with traction structures, interpreted to result from oscillatory flows. These are intercalated with concave-up lenses, up to 15 m thick, of sigmoidally-bedded, amalgamated sandstones, which preserve ripple casts on bed-bases, interpreted as deposits at the head of a deep-marine canyon. Palaeo-flow was eastward, into the sub-basin margin. On the adjacent margin of the sub-basin down-dip, stacked and amalgamated sandstones and conglomerates represent the fill of a submarine channel complex, at least 3 km wide. The channels are inferred to have been fed by the up-dip canyon, which traversed the intervening structural high; similar relationships are seen in the bathymetry data. Seismic studies on this margin demonstrate that multiple phases of canyon cut and fill may occur, with downstream architectural evolution comparable to that seen at outcrop demonstrating that detached canyons may act as sediment conduits. Breaching of developing sea-floor structures by detached canyons can modify tortuous sediment pathways, supplying sediment to otherwise starved areas of the slope

Systèmes antennaires reconfigurables pour l'observation spatiale

This thesis focuses on the design of ultrawideband reconfigurable antennas. The objective of this study is to integrate all the antennas of observation on satellites into a single radiating panel and make it reconfigurable. Works presented in this document are focused on the design of spiral antennas and on their possible improvements. Thereby, a new topology of square spiral antenna reconfigurable into an array of four smaller square spiral antennas is shown. This reconfiguration allows increasing the surface efficiency of the structure while offering new possibilities of utilization to the antenna and improving its performance. Characteristics and performance of both configurations in frozen states are presented. Breadboards and measurements are also presented in order to validate the functioning of the antenna. Then, several improvements of this structure are studied and a possible application. Finally, a solution for improving the functioning of spiral antennas printed over a metallic ground plane is presented. This solution permits to remove a null of radiation when the distance between the antenna and the ground plane is a multiple of the half wavelength. In this way, its bandwidth can be doubled without losing the half of the energy like with absorbers. This technique consists in adding a parasitic radiating element over the antenna. This element is fed by coupling to the spiral antenna and radiates at the frequency of the null of radiation. This element is narrowband, so antenna performance remains unchanged at the other frequencies of the bandwidth. A structure using this concept has been made in order to validate its functioning.Cette thèse s’intéresse à la conception d’antennes ultra large bande reconfigurables. Cette étude a été motivée par le souhait de regrouper l’ensemble des antennes d’observation présentes sur les satellites en un panneau rayonnant unique afin de pouvoir réduire la taille de ces derniers. Les travaux présentés dans ce mémoire sont donc principalement axés sur la conception d’antennes spirales et sur les améliorations qui peuvent leur être apportées. Ainsi, une nouvelle topologie d’antenne spirale carrée reconfigurable en un réseau de quatre antennes spirales carrées plus petites sur la même ouverture rayonnante est exposée. Cette reconfiguration permet d’augmenter l’efficacité de surface de la structure tout en offrant de nouvelles possibilités d’utilisation à l’antenne et en améliorant ses performances. Les caractéristiques et les performances des deux configurations en états figés sont détaillées. Les maquettes réalisées et les résultats de mesure sont également présentés afin de valider le fonctionnement de l’antenne. Ensuite, différentes améliorations de cette structure sont présentées ainsi qu’une application possible. Enfin, une solution permettant d’améliorer le fonctionnement des antennes spirales imprimées au-dessus d’un plan de masse est décrite. En effet, cette solution permet de supprimer un nul de rayonnement lorsque l’antenne se situe à une demi-longueur d’onde du plan de masse. Sa bande passante d’utilisation peut ainsi être potentiellement doublée sans perdre la moitié de l’énergie comme avec l’utilisation d’absorbants. Cette technique consiste à ajouter un élément rayonnant parasite au-dessus de l’antenne. Cet élément est excité par couplage à l’antenne spirale et rayonne à la fréquence du nul de rayonnement. Cet élément étant faible bande, il ne dégrade pas le fonctionnement de l’antenne aux autres fréquences de la bande passante. Une structure utilisant ce concept a été réalisée afin de valider son fonctionnement

Reconfigurable antenna systems for space observation

Cette thèse s’intéresse à la conception d’antennes ultra large bande reconfigurables. Cette étude a été motivée par le souhait de regrouper l’ensemble des antennes d’observation présentes sur les satellites en un panneau rayonnant unique afin de pouvoir réduire la taille de ces derniers. Les travaux présentés dans ce mémoire sont donc principalement axés sur la conception d’antennes spirales et sur les améliorations qui peuvent leur être apportées. Ainsi, une nouvelle topologie d’antenne spirale carrée reconfigurable en un réseau de quatre antennes spirales carrées plus petites sur la même ouverture rayonnante est exposée. Cette reconfiguration permet d’augmenter l’efficacité de surface de la structure tout en offrant de nouvelles possibilités d’utilisation à l’antenne et en améliorant ses performances. Les caractéristiques et les performances des deux configurations en états figés sont détaillées. Les maquettes réalisées et les résultats de mesure sont également présentés afin de valider le fonctionnement de l’antenne. Ensuite, différentes améliorations de cette structure sont présentées ainsi qu’une application possible. Enfin, une solution permettant d’améliorer le fonctionnement des antennes spirales imprimées au-dessus d’un plan de masse est décrite. En effet, cette solution permet de supprimer un nul de rayonnement lorsque l’antenne se situe à une demi-longueur d’onde du plan de masse. Sa bande passante d’utilisation peut ainsi être potentiellement doublée sans perdre la moitié de l’énergie comme avec l’utilisation d’absorbants. Cette technique consiste à ajouter un élément rayonnant parasite au-dessus de l’antenne. Cet élément est excité par couplage à l’antenne spirale et rayonne à la fréquence du nul de rayonnement. Cet élément étant faible bande, il ne dégrade pas le fonctionnement de l’antenne aux autres fréquences de la bande passante. Une structure utilisant ce concept a été réalisée afin de valider son fonctionnement.This thesis focuses on the design of ultrawideband reconfigurable antennas. The objective of this study is to integrate all the antennas of observation on satellites into a single radiating panel and make it reconfigurable. Works presented in this document are focused on the design of spiral antennas and on their possible improvements. Thereby, a new topology of square spiral antenna reconfigurable into an array of four smaller square spiral antennas is shown. This reconfiguration allows increasing the surface efficiency of the structure while offering new possibilities of utilization to the antenna and improving its performance. Characteristics and performance of both configurations in frozen states are presented. Breadboards and measurements are also presented in order to validate the functioning of the antenna. Then, several improvements of this structure are studied and a possible application. Finally, a solution for improving the functioning of spiral antennas printed over a metallic ground plane is presented. This solution permits to remove a null of radiation when the distance between the antenna and the ground plane is a multiple of the half wavelength. In this way, its bandwidth can be doubled without losing the half of the energy like with absorbers. This technique consists in adding a parasitic radiating element over the antenna. This element is fed by coupling to the spiral antenna and radiates at the frequency of the null of radiation. This element is narrowband, so antenna performance remains unchanged at the other frequencies of the bandwidth. A structure using this concept has been made in order to validate its functioning

La déformation synsédimentaire des bassins paléogènes de l'Arc de Castellane (Annot, Barrême, Saint-Antonin)

E.N.S.M.P. Mé",. Sc. de la Terre, ,,° 43 - 2001 -Les bassins d'avant-pays alpins constituent des domaines où il est possible de caractériser et de quantifier les relations entre la tectonique et la sédimentation. . Nous avons ciblé notre étude sur les bassins marins paléogènes d'Annot, Barrême et Saint--Antonin dans le domaine externe des Alpes méridionales. Les nouvelles études biostratigraphiques montrent un diachronisme insoupçonné entre le système d'Annot/Saint-Antonin et le bassin de Barrême, et des taux de sédimentation contrastés dans le temps et dans l'espace. L'analyse verticale de faciès aboutit à proposer un découpage en cortèges sédimentaires. Nous observons des évolutions semblables et synchrones de l'enregistrement des séquences de dépôts, entre les bassins d'Annot et Saint-Antonin, et entre les différents systèmes deltaïques de Barrême. L'intégration des données biostratigraphiques nous permet de corréler le découpage séquentiel entre les bassins, mais également avec les standards chronostratigraphiques. L'histoire marine des bassins paléogènes de l'arc de Castellane est compatible avec la superséquence TA4. Cependant la déformation active dans les bassins d'avant-pays, tout d'abord liée à la subsidence tectonique du foredeep puis à la surrection, conduit à une modulation de l'enregistrement eustatique. La subsidence tectonique amplifie les remontées et atténue les chutes eustatiques. Ce processus est diachrone et d'intensité variable. La surrection, également diachrone, entraîne une baisse progressive de l'espace disponible et génère un régime de régression forcée. Là où la déformation plicative est marquée (à Saint-Antonin et à Barrême), la superposition des oscillations du niveau marin génère des éventails synsédimentaires. Une approche pluridisciplinaire nous a permis d'apprécier les interférences localisées entre les mécanismes structuraux, sédimentaires et eustatiques, entraînant ainsi des architectures variées du remplissage sédimentaire des bassins d'avant-pays paléogène des Alpes-méridionalespas de résum