An inverse function theorem in Fréchet-Spaces

AbstractA technical inverse function theorem of Nash-Moser type is proved for maps between Fréchet spaces allowing smoothing operators. A counterexample shows that the growth requirements on the rightinverse of the linearized map needed are minimal

On Extracting Mechanical Properties from Nanoindentation at Temperatures up to 1000∘^{\circ}C

Alloyed MCrAlY bond coats, where M is usually cobalt and/or nickel, are essential parts of modern turbine blades, imparting environmental resistance while mediating thermal expansivity differences. Nanoindentation allows the determination of their properties without the complexities of traditional mechanical tests, but was not previously possible near turbine operating temperatures. Here, we determine the hardness and modulus of CMSX-4 and an Amdry-386 bond coat by nanoindentation up to 1000$^{\circ}$C. Both materials exhibit a constant hardness until 400$^{\circ}$C followed by considerable softening, which in CMSX-4 is attributed to the multiple slip systems operating underneath a Berkovich indenter. The creep behaviour has been investigated via the nanoindentation hold segments. Above 700$^{\circ}$C, the observed creep exponents match the temperature-dependence of literature values in CMSX-4. In Amdry-386, nanoindentation produces creep exponents very close to literature data, implying high-temperature nanoindentation may be powerful in characterising these coatings and providing inputs for material, model and process optimisations

Almost reducibility for finitely differentiable SL(2,R)-valued quasi-periodic cocycles

Quasi-periodic cocycles with a diophantine frequency and with values in SL(2,R) are shown to be almost reducible as long as they are close enough to a constant, in the topology of k times differentiable functions, with k great enough. Almost reducibility is obtained by analytic approximation after a loss of differentiability which only depends on the frequency and on the constant part. As in the analytic case, if their fibered rotation number is diophantine or rational with respect to the frequency, such cocycles are in fact reducible. This extends Eliasson's theorem on Schr\"odinger cocycles to the differentiable case

Dentine decalcification and smear layer removal by different ethylenediaminetetraacetic acid and 1-hydroxyethane-1,1-diphosphonic acid species

AIM To compare solutions of di- and tetrasodium ethylenediaminetetraacetic acid (EDTA) and 1-hydroxyethane-1,1-diphosphonic acid (HEDP) regarding their ability to solubilize calcium from dentine and remove smear layer. METHODOLOGY Solutions with a molarity corresponding to that of 17% Na EDTA (pH adjusted to 8.5) were prepared by dissolving Na and Na salts of HEDP (etidronate), or Na EDTA in deionized water. Standardized root dentine discs covered by a smear layer were prepared from human third molars. These discs (n = 10 per group) were immersed in test solutions or phosphate-buffered saline for 1 min. The dissolved Ca was determined by atomic absorption spectroscopy, apparently opened dentinal tubules by laser scanning microscopy and automated image analysis. Ca values were compared between groups by parametric, tubular areas by nonparametric methods, α = 0.05. RESULTS Solutions prepared from the tetrasodium salts were alkaline (pH 11.3-11.4), whilst counterparts made from the disodium salts were acidic. The EDTA solutions dissolved more calcium than the HEDP counterparts (P < 0.05); solutions prepared with the disodium salts dissolved more calcium than those made from the tetrasodium salts (P < 0.05). There was a high correlation between dissolved calcium and the apparently opened tubular areas (Spearman's ρ = 0.81). Differences between groups regarding opened tubules were similar to those observed regarding the Ca values, with a slightly reduced discerning power due to high variance. CONCLUSION Calcium chelation and thus smear layer removal by EDTA and HEDP are influenced by pH

Spectral Analysis of GRBs Measured by RHESSI

The Ge spectrometer of the RHESSI satellite is sensitive to Gamma Ray Bursts (GRBs) from about 40 keV up to 17 MeV, thus ideally complementing the Swift/BAT instrument whose sensitivity decreases above 150 keV. We present preliminary results of spectral fits of RHESSI GRB data. After describing our method, the RHESSI results are discussed and compared with Swift and Konus.Comment: 4 pages, 4 figures, conference proceedings, 'Swift and GRBs: Unveiling the Relativistic Universe', San Servolo, Venice, 5-9 June 2006, to appear in Il Nouvo Ciment

Leader corruption depends on power and testosterone

We used incentivized experimental games to manipulate leader power-the number of followers and the discretion leaders had to enforce their will. Leaders had complete autonomy in deciding payouts to themselves and their followers. Although leaders could make prosocial decisions to benefit the public good they could also abuse their power by invoking antisocial decisions, which reduced the total payouts to the group but increased leader's earnings. In Study 1 (N = 478), we found that both amount of followers and discretionary choices independently predicted leader corruption. In Study 2 (N = 240), we examined how power and individual differences (e.g., personality, hormones) affected leader corruption over time; power interacted with testosterone in predicting corruption, which was highest when leader power and baseline testosterone were both high. Honesty predicted initial level of leader antisocial decisions; however, honesty did not shield leaders from the corruptive effect of power

The role of VEGF receptors in angiogenesis; complex partnerships

Abstract.: Vascular endothelial growth factors (VEGFs) regulate blood and lymphatic vessel development and homeostasis but also have profound effects on neural cells. VEGFs are predominantly produced by endothelial, hematopoietic and stromal cells in response to hypoxia and upon stimulation with growth factors such as transforming growth factors, interleukins or platelet-derived growth factor. VEGFs bind to three variants of type III receptor tyrosine kinases, VEGF receptor 1, 2 and 3. Each VEGF isoform binds to a particular subset of these receptors giving rise to the formation of receptor homo- and heterodimers that activate discrete signaling pathways. Signal specificity of VEGF receptors is further modulated upon recruitment of coreceptors, such as neuropilins, heparan sulfate, integrins or cadherins. Here we summarize the knowledge accumulated since the discovery of these proteins more than 20years ago with the emphasis on the signaling pathways activated by VEGF receptors in endothelial cells during cell migration, growth and differentiatio

Influence of the pre-treatment of glass substrates on Laser-Induced Backside Wet Etching using NIR Nanosecond-Pulses and Cu-based solutions

Laser induced backside wet etching (LIBWE) has shown to be a promising tool for the micro-structuring of transparent materials. Our group has investigated LIBWE using NIR ns-laser pulses and Cu-based absorber liquids. Focus of this paper is to investigate the influence of the pre-treatment of the transparent substrate on ablation. For this purpose experiments were done on untreated and silanized soda lime glass surfaces. Our results show that depending on the absorber liquid the silanization of the substrate either enhances or delays the ablation. Possible ablation models for the different experimental settings will be discussed

Laser-induced chemical liquid-phase deposition of copper on transparent substrates

Laser-induced chemical liquid phase deposition allows maskless manufacturing of metallic structures on the surface of dielectrics and is prospected to be a promising tool in the field of microelectronics and microfluidics. The aim of the work presented here is to combine this deposition method with a related micro-structuring method known as laser-induced backside wet etching. Fabricating both, microstructured surface structures and subsequent deposition of conducting patterns within the same setup would be an interesting tool for rapid prototyping.To demonstrate the functional principle of this combined approach conductive copper lines were deposited at the backside of both polished and structured soda lime glass substrates by using a focused, scanning ns-pulsed Ytterbium fiber laser at 532nm wavelength. The deposition process is initiated by a photo induced reaction of a CuSO4-based liquid precursor in contact with the backside of the substrate. The obtained metallic copper deposits are crystalline, stable under ambient conditions and have a conductivity in the same order of magnitude as bulk copper

A novel Model for the Mechanism of Laser-Induced Back Side Wet Etching in Aqueous Cu Solutions using ns Pulses at 1064nm

Laser induced back side wet etching has shown to be a promising tool for the micro-structuring of transparent materials. Detailed studies have been performed using UV excimer laser sources, aromatic hydrocarbon and liquid metal absorbers. Only little work is reported however using aqueous Cu solutions as absorbers and ns laser pulses at 1064 nm wavelength. We present a novel model for this specific setup. Our experiments indicate that physisorbed Cu2+ ions at the polar glass surface absorb the laser light. This leads to local thermal stresses in the glass and subsequent micro-ablation