Moisture resistance of SU-8 and KMPR as structural material for integrated gaseous detectors

This paper treats the moisture resistance of SU-8 and KMPR, two photoresists considered as structural material in microsystems. Our experiments focus on the moisture resistance of newly developed radiation imaging detectors containing these resists. Since these microsystems will be used unpackaged, they are susceptible to all kinds of environmental conditions. Already after one day of exposure to a humid condition the structural integrity and adhesion of SU-8 structures, measured by a shear test is drastically reduced. KMPR photoresist shows much stronger moisture resistance properties, making it a suitable alternative in our application. © 2008 Elsevier Science. All rights reserved

Decay of flux vacua to nothing

We construct instanton solutions describing the decay of flux compactifications of a $6d$ gauge theory by generalizing the Kaluza-Klein bubble of nothing. The surface of the bubble is described by a smooth magnetically charged solitonic brane whose asymptotic flux is precisely that responsible for stabilizing the 4d compactification. We describe several instances of bubble geometries for the various vacua occurring in a $6d$ Einstein-Maxwell theory namely, AdS_4 x S^2, R^{1,3} x S^2, and dS_4 x S^2. Unlike conventional solutions, the bubbles of nothing introduced here occur where a {\em two}-sphere compactification manifold homogeneously degenerates.Comment: 31 pages, 15 figure

Magnetic ordering in GdNi2B2C revisited by resonant x-ray scattering: evidence for the double-q model

Recent theoretical efforts aimed at understanding the nature of antiferromagnetic ordering in GdNi2B2C predicted double-q ordering. Here we employ resonant elastic x-ray scattering to test this theory against the formerly proposed, single-q ordering scenario. Our study reveals a satellite reflection associated with a mixed-order component propagation wave vector, viz., (q_a,2q_b,0) with q_b = q_a approx= 0.55 reciprocal lattice units, the presence of which is incompatible with single-q ordering but is expected from the double-q model. A (3q_a,0,0) wave vector (i.e., third-order) satellite is also observed, again in line with the double-q model. The temperature dependencies of these along with that of a first-order satellite are compared with calculations based on the double-q model and reasonable qualitative agreement is found. By examining the azimuthal dependence of first-order satellite scattering, we show the magnetic order to be, as predicted, elliptically polarized at base temperature and find the temperature dependence of the "out of a-b plane" moment component to be in fairly good agreement with calculation. Our results provide qualitative support for the double-q model and thus in turn corroborate the explanation for the "magnetoelastic paradox" offered by this model.Comment: 8 pages, 5 figures. Submitted to Phys. Rev.

Sustavi proizvodnje u južnoj Europi: Huelva (Španjolska)

The strawberry is one of the most important crops in the Province of Huelva, south western Spain. More than 90% of the national production is harvested in this area, which means over 35% of the total production of the EU. During the 2007-2008 season, the acreage used for that crop was estimated at over 6.000 ha, and the production of 240.000 tons. The most widely used strawberry cultivar was ‘Camarosa’ (70%) followed by ‘Candonga’ (12%), with lower yields but better fruit quality, ‘Festival’ (12%), ‘Ventana’ (2%) and other minor varieties like ‘Chiflón’, ‘Aguedilla’ and ‘Coral’. The raspberry crop acreage for the 2007-2008 season has been estimated at around 1.330ha, increasing over 2.5% compared to the previous season. Most plants used to set the crop are multiplied in low elevation nurseries within the same area of the production fields, and only a small amount of plants come from high elevation nurseries in the north of Spain. The most common cultivar used is ‘Glen-Lyon’, with more than 90% of the acreage under the crop. The development of the blueberry crop in Huelva has also been important for the area during the last five years. Currently, more than 750 ha are used for the crop, but only 26 ha are in ecological production, and 90% of this acreage, is located in the village Almonte. 95% of the blueberry production is exported to Germany, United Kingdom, Belgium, the Netherlands and Switzerland. Early-season yield cultivars like ‘Misty’, ‘Sharpblue’ and ‘O`neal’ are widely used (70%) but also mid-season yield cultivars, like ‘Star’, can be found in the area. The export marketing season starts in February and lasts until June, but market picks are usually found in April, May and June. Each cultivar presents a different harvest season which period can take more than 45 days.Jagoda je jedan od najvažnijih usjeva u pokrajini Huelva, jugozapadna Španjolska. Više od 90% nacionalne proizvodnje dobiva se na tom području, što znači preko 36% ukupne proizvodnje EU. U sezoni 2997-2008. površina namijenjena tom usjevu procijenjena je na preko 6,000 ha a proizvodnja na 240.000 tona. Najviše upotrebljavan kultivar jagode bio je Camarosa (70%), a slijedili su Candonga (12%) manjih prinosa ali bolje kakvoće voća, zatim Festival (12%) Ventana (2%) te druge manje varijante kao Chiflon i Coral. Površina malina za 2007-2008 procijenjena je na oko 1.330 ha s povećanjem preko 2.5% u usporedbi s prethodnom sezonom.Većina biljaka za nasade se razmnaža u rasadnicima niskog rasta unutar područja proizvodnih nasada i samo malen broj biljaka dolazi iz rasadnika biljaka visokog rasta na sjeveru Španjolske. Najčešći kultivar je Glen-Lyon s više od 90% površina. Razvoj nasada borovnice u Helvi također je važan za to područje zadnjih pet godina.Trenutačno više od 750 ha pokriva ova kultura ali samo 26 ha je pod ekološkom proizvodnjom a 90% te površine nalazi se u selu Almonte. U Njemačku, Ujedinjeno Kraljevstvo, Belgiju, Nizozemsku i Švicarsku izvozi se 95% proizvodnje borovnica. Rani kultivari kao Misty, Sharpblue i O Neal naširoko se upogrebljavaju (70%) ali isto tako i kultivari koji dozrijevaju sredinom sezone kao Star mogu se naći u ovom području. Sezona izvoza počinje u veljači i traje do lipnja,ali branje za trgovinu obično se odvija u travnju, svibnju i lipnju.Svaki kultivar ima drugačiju sezonu branja a to razdoblje može trajati 45 dana.

Diffusion of hydrogen interstitials in the near-surface region of Pd(111) under the influence of surface coverage and external static electric fields

Past scanning tunneling microscopy (STM) experiments of H manipulation on Pd(111), at low temperature, have shown that it is possible to induce diffusion of surface species as well as of those deeply buried under the surface. Several questions remain open regarding the role of subsurface site occupancies. In the present work, the interaction potential of H atoms with Pd(111) under various H coverage conditions is determined by means of density functional theory calculations in order to provide an answer to two of these questions: (i) whether subsurface sites are the final locations for the H impurities that attempt to emerge from bulk regions, and (ii) whether penetration of the surface is a competing route of on-surface diffusion during depletion of surface H on densely covered Pd(111). We find that a high H coverage has the effect of blocking resurfacing of H atoms travelling from below, which would otherwise reach the surface fcc sites, but it hardly alters deeper diffusion energy barriers. Penetration is unlikely and restricted to high occupancies of hcp hollows. In agreement with experiments, the Pd lattice expands vertically as a consequence of H atoms being blocked at subsurface sites, and surface H enhances this expansion. STM tip effects are included in the calculations self-consistently as an external static electric field. The main contribution to the induced surface electric dipoles originates from the Pd substrate polarisability. We find that the electric field has a non- negligible effect on the H-Pd potential in the vicinity of the topmost Pd atomic layer, yet typical STM intensities of 1-2 VÅ−1 are insufficient to invert the stabilities of the surface and subsurface equilibrium sites

Significant differences in incubation times in sheep infected with bovine spongiform encephalopathy result from variation at codon 141 in the PRNP gene

The susceptibility of sheep to prion infection is linked to variation in the PRNP gene, which encodes the prion protein. Common polymorphisms occur at codons 136, 154 and 171. Sheep which are homozygous for the A<sub>136</sub>R<sub>154</sub>Q<sub>171</sub> allele are the most susceptible to bovine spongiform encephalopathy (BSE). The effect of other polymorphisms on BSE susceptibility is unknown. We orally infected ARQ/ARQ Cheviot sheep with equal amounts of BSE brain homogenate and a range of incubation periods was observed. When we segregated sheep according to the amino acid (L or F) encoded at codon 141 of the PRNP gene, the shortest incubation period was observed in LL141 sheep, whilst incubation periods in FF<sub>141</sub> and LF<sub>141</sub> sheep were significantly longer. No statistically significant differences existed in the expression of total prion protein or the disease-associated isoform in BSE-infected sheep within each genotype subgroup. This suggested that the amino acid encoded at codon 141 probably affects incubation times through direct effects on protein misfolding rates