Measurements of the group delay and the group delay dispersion with resonance scanning interferometer

We developed a method for group delay and group delay dispersion measurements, based on location of interference resonance peaks. Such resonance peaks can be observed in transmittance or in reflectance when two mirrors are placed parallel to each other and separated by a thin air spacer. By using a novel approach, based on simultaneous processing of the data acquired for different spacer distances we obtained reliable results with high resolution. Measurements were performed both in transmittance and reflectance layouts depending on the reflectivity of the mirror to be measured. The developed method allows dispersion measurements of ultraviolet mirrors and ultra-broadband mirrors spanning more than one optical octave to be performed

Travelling and splitting of a wave of hedgehog expression involved in spider-head segmentation

During development segmentation is a process that generates a spatial periodic pattern. Peak splitting of waves of gene expression is a mathematically predicted, simple strategy accounting for this type of process, but it has not been well characterized biologically. Here we show temporally repeated splitting of gene expression into stripes that is associated with head axis growth in the spider Achaearanea embryo. Preceding segmentation, a wave of hedgehog homologue gene expression is observed to travel posteriorly during development stage 6. This stripe, co-expressing an orthodenticle homologue, undergoes two cycles of splitting and shifting accompanied by convergent extension, serving as a generative zone for the head segments. The two orthodenticle and odd-paired homologues are identified as targets of Hedgehog signalling, and evidence suggests that their activities mediate feedback to maintain the head generative zone and to promote stripe splitting in this zone. We propose that the 'stripe-splitting' strategy employs genetic components shared with Drosophila blastoderm subdivision, which are required for participation in an autoregulatory signalling network

Identification of Novel Functional Inhibitors of Acid Sphingomyelinase

We describe a hitherto unknown feature for 27 small drug-like molecules, namely functional inhibition of acid sphingomyelinase (ASM). These entities named FIASMAs (Functional Inhibitors of Acid SphingoMyelinAse), therefore, can be potentially used to treat diseases associated with enhanced activity of ASM, such as Alzheimer's disease, major depression, radiation- and chemotherapy-induced apoptosis and endotoxic shock syndrome. Residual activity of ASM measured in the presence of 10 µM drug concentration shows a bimodal distribution; thus the tested drugs can be classified into two groups with lower and higher inhibitory activity. All FIASMAs share distinct physicochemical properties in showing lipophilic and weakly basic properties. Hierarchical clustering of Tanimoto coefficients revealed that FIASMAs occur among drugs of various chemical scaffolds. Moreover, FIASMAs more frequently violate Lipinski's Rule-of-Five than compounds without effect on ASM. Inhibition of ASM appears to be associated with good permeability across the blood-brain barrier. In the present investigation, we developed a novel structure-property-activity relationship by using a random forest-based binary classification learner. Virtual screening revealed that only six out of 768 (0.78%) compounds of natural products functionally inhibit ASM, whereas this inhibitory activity occurs in 135 out of 2028 (6.66%) drugs licensed for medical use in humans

The disruption of proteostasis in neurodegenerative diseases

Cells count on surveillance systems to monitor and protect the cellular proteome which, besides being highly heterogeneous, is constantly being challenged by intrinsic and environmental factors. In this context, the proteostasis network (PN) is essential to achieve a stable and functional proteome. Disruption of the PN is associated with aging and can lead to and/or potentiate the occurrence of many neurodegenerative diseases (ND). This not only emphasizes the importance of the PN in health span and aging but also how its modulation can be a potential target for intervention and treatment of human diseases.info:eu-repo/semantics/publishedVersio

Mineral separation by centrifugation with heavy liquids : improvement of a method

The centrifugation increases the speed gravity separation of finely ground samples with heavy liquids. But contamination of the sink fraction by particles of the float fraction might occur when emptying the centrifugation tubes. A very simple, efficient and cheap device, preventing this disadvantage, is described here. In addition, it reduces appreciably the handling of the highly toxic heavy liquids. This device consists of a tube-funnel which is placed into the centrifugation tube. During the centrifugation the sink fraction falls to the bottom of the centrifugation tube through the funnel; this latter, containing the float fraction, is then closed with a PVC rod and is taken out of the centrifugation tube. This device has been used successfully for samples with a strong interlocking of opaque minerals and matrix or with thin coatings of opaque minerals on quartz grains, which made very fine grinding necessary.Le recours à la centrifugation, pour accélérer la séparation gravifique de minéraux, finement broyés, au moyen de liqueurs lourdes, se heurte à des problèmes de contamination de la fraction lourde par des particules de la fraction légère lorsque l'on vide des éprouvettes. Il est décrit ici un dispositif simple, efficace, et bon marché, qui supprime cet inconvénient. Il réduit de plus au maximum les manutentions de liqueurs lourdes, hautement toxiques. Ce dispositif consiste en un tube- entonnoir placé à l'intérieur d'une éprouvette. Pendant la centrifugation, la fraction lourde se concentre au fond de l'éprouvette après avoir traversé l'entonnoir; par la suite, ce dernier, trappant la fraction légère, est fermé au moyen d'une tige de PVC et est retiré du tube de la centrifugeuse. Ce dispositif a été utilisé avec succès pour des échantillons où le minerai et la gangue étaient finement enchevêtrés, ou où de fines pellicules de minerai étaient plaquées sur des grains de quartz, ce qui avait nécessité un très fin broyage.Zentrifugieren beschleunigt zwar die Schwermineralabtrennung aus fein gemahlenen Proben in Schwereflüssigkeiten, birgt jedoch die Gefahr, dass bei der Leerung der Zentrifugengläser die Schwermineralfraktion durch die Leichtmineralfraktion verunreinigt wird. Dieser Nachteil wird durch das hier beschriebene einfache, wirkungsvolle und billige Hilfsmittel vermieden, wodurch zugleich der Umgang mit den hochgiftigen Schwereflüssigkeiten auf einem Mindestmass gehalten werden kann. Ein im unteren Teil trichterförmiger Glaszylinder wird in ein Zentrifugenglas gesetzt; während des Schleudervorganges fällt die Schwermineralfraktion durch die Trichteröffnung auf den Boden des Zentrifugenglases. Der Trichtereinsatz wird nach Verschliessen seiner Öffnung mit einem PVC-Stäbchen mitsamt der leichteren Fraktion aus dem Zentrifugenglas herausgehoben. Das beschriebene Hilfsmittel wurde sehr erfolgreich bei Proben angewandt, die zur Mineraltrennung sehr fein gemahlen werden mussten, z. B. wenn die Grundmasse sehr fein mit den Erzmineralien verwachsen war oder wenn in einem Sandstein die Opakbestandteile feinste Häutchen auf den Quarzkörnern bildeten

Measurements Of The Group Delay Dispersion With Resonance Scanning Interferometer

We developed a Resonance Scanning Interferometer for group delay dispersion measurements based on inter-mirror spacer resonances. High resolution is achieved by simultaneous processing of measurement scans obtained for different spacer thicknesses. © 2013 IEEE