Coriolis force in Geophysics: an elementary introduction and examples

We show how Geophysics may illustrate and thus improve classical Mechanics lectures concerning the study of Coriolis force effects. We are then interested in atmospheric as well as oceanic phenomena we are familiar with, and are for that reason of pedagogical and practical interest. Our aim is to model them in a very simple way to bring out the physical phenomena that are involved.Comment: Accepted for publication in European Journal of Physic

An accurate and interpretable model for siRNA efficacy prediction

BACKGROUND: The use of exogenous small interfering RNAs (siRNAs) for gene silencing has quickly become a widespread molecular tool providing a powerful means for gene functional study and new drug target identification. Although considerable progress has been made recently in understanding how the RNAi pathway mediates gene silencing, the design of potent siRNAs remains challenging. RESULTS: We propose a simple linear model combining basic features of siRNA sequences for siRNA efficacy prediction. Trained and tested on a large dataset of siRNA sequences made recently available, it performs as well as more complex state-of-the-art models in terms of potency prediction accuracy, with the advantage of being directly interpretable. The analysis of this linear model allows us to detect and quantify the effect of nucleotide preferences at particular positions, including previously known and new observations. We also detect and quantify a strong propensity of potent siRNAs to contain short asymmetric motifs in their sequence, and show that, surprisingly, these motifs alone contain at least as much relevant information for potency prediction as the nucleotide preferences for particular positions. CONCLUSION: The model proposed for prediction of siRNA potency is as accurate as a state-of-the-art nonlinear model and is easily interpretable in terms of biological features. It is freely available on the web a

Enchytraeus albidus Microarray: Enrichment, Design, Annotation and Database (EnchyBASE)

Enchytraeus albidus (Oligochaeta) is an ecologically relevant species used as standard test organisms for risk assessment. Effects of stressors in this species are commonly determined at the population level using reproduction and survival as endpoints. The assessment of transcriptomic responses can be very useful e.g. to understand underlying mechanisms of toxicity with gene expression fingerprinting. In the present paper the following is being addressed: 1) development of suppressive subtractive hybridization (SSH) libraries enriched for differentially expressed genes after metal and pesticide exposures; 2) sequencing and characterization of all generated cDNA inserts; 3) development of a publicly available genomic database on E. albidus. A total of 2100 Expressed Sequence Tags (ESTs) were isolated, sequenced and assembled into 1124 clusters (947 singletons and 177 contigs). From these sequences, 41% matched known proteins in GenBank (BLASTX, e-value≤10-5) and 37% had at least one Gene Ontology (GO) term assigned. In total, 5.5% of the sequences were assigned to a metabolic pathway, based on KEGG. With this new sequencing information, an Agilent custom oligonucleotide microarray was designed, representing a potential tool for transcriptomic studies. EnchyBASE (http://bioinformatics.ua.pt/enchybase/) was developed as a web freely available database containing genomic information on E. albidus and will be further extended in the near future for other enchytraeid species. The database so far includes all ESTs generated for E. albidus from three cDNA libraries. This information can be downloaded and applied in functional genomics and transcription studies

AlInN/GaN a suitable HEMT device for extremely high power high frequency applications

AlInN/GaN unpassivated High Electron Mobility Transistor (HEMT) on Sapphire substrate has yielded a maximum drain current density close to 2 A/mm in steady state. Superior gate length downscaling than AlGaN/GaN devices has been observed owing to the possibility of the use of ultra thin barrier layer while keeping extremely high sheet carrier density. We reached an extrinsic current gain cut-off frequency of 70 GHz for a 0.08 mu m gate length device. Large signal measurements reveal a relatively low RF power dispersion. Indeed, at 10 GHz we performed for the first time power measurements on such a HEMT structure. We achieved 1.5 W/mm output power density at low bias condition (V-DS = 15V) in agreement with the expected power in spite of a strong thermal effect due to the sapphire substrate, a large leakage current in the Schottky diode characteristic and a low buffer layer resistivity. These results demonstrate the great potential of this structure for extremely high power high frequency applications

Na/Ca exchange by NCX3 is vital in skeletal muscle physiology: Highlight by the journal of Clinical Investigation

info:eu-repo/semantics/publishe

Small-signal characteristics of AlInN/GaN HEMTs

DC and RF measurements of an emerging AIInN/GaN high electron mobility transistor (HEMT) technology for power performances are reported. High electron transport properties in this structure attributed to the material quality are demonstrated. Indeed, in spite of a basic technology which provides high access resistances, high frequency performances with a cutoff and maximum oscillation frequencies about 26 and 40 GHz, respectively, at V-DS = 10 V were achieved. A maximum drain current density more than 1.3 A/mm with a pinch-off breakdown voltage about 40 V without any passivation was obtained. These results show that this device is very promising for high power performances at high frequency