Copy Number Variation and Transposable Elements Feature in Recent, Ongoing Adaptation at the Cyp6g1 Locus

The increased transcription of the Cyp6g1 gene of Drosophila melanogaster, and consequent resistance to insecticides such as DDT, is a widely cited example of adaptation mediated by cis-regulatory change. A fragment of an Accord transposable element inserted upstream of the Cyp6g1 gene is causally associated with resistance and has spread to high frequencies in populations around the world since the 1940s. Here we report the existence of a natural allelic series at this locus of D. melanogaster, involving copy number variation of Cyp6g1, and two additional transposable element insertions (a P and an HMS-Beagle). We provide evidence that this genetic variation underpins phenotypic variation, as the more derived the allele, the greater the level of DDT resistance. Tracking the spatial and temporal patterns of allele frequency changes indicates that the multiple steps of the allelic series are adaptive. Further, a DDT association study shows that the most resistant allele, Cyp6g1-[BP], is greatly enriched in the top 5% of the phenotypic distribution and accounts for ∼16% of the underlying phenotypic variation in resistance to DDT. In contrast, copy number variation for another candidate resistance gene, Cyp12d1, is not associated with resistance. Thus the Cyp6g1 locus is a major contributor to DDT resistance in field populations, and evolution at this locus features multiple adaptive steps occurring in rapid succession

Physical Properties of (M2\text{}_{2}Cu2\text{}_{2}O3\text{}_{3})m\text{}_{m}(CuO2\text{}_{2})n\text{}_{n} (M = Ca, Sr, Bi) Single Crystals with Bi-2212 Phase on their Surface

The structural, optical, and magnetic properties are studied in the (M$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{3}$)$\text{}_{m}$(CuO$\text{}_{2}$)$\text{}_{n}$-type single crystals with the surface on which the Bi-2212-type phase was indicated. The physical properties of such samples were interpreted to some extent by the contributions of two phases. When the secondary phases on the surface of the samples were removed by mechanical polishing or etching by Ar$\text{}^{+}$-ion plasma, the physical properties were typical of the (M$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{3}$)$\text{}_{m}$(CuO$\text{}_{2}$)$\text{}_{n}$-type crystals. The optical method was shown to be effective for indication of secondary Bi-rich phases on the surface of (M$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{3}$)$\text{}_{m}$(CuO$\text{}_{2}$)$\text{}_{n}$ samples

Physical Properties of (M 2

The structural, optical, and magnetic properties are studied in the (M$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{3}$)$\text{}_{m}$(CuO$\text{}_{2}$)$\text{}_{n}$-type single crystals with the surface on which the Bi-2212-type phase was indicated. The physical properties of such samples were interpreted to some extent by the contributions of two phases. When the secondary phases on the surface of the samples were removed by mechanical polishing or etching by Ar$\text{}^{+}$-ion plasma, the physical properties were typical of the (M$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{3}$)$\text{}_{m}$(CuO$\text{}_{2}$)$\text{}_{n}$-type crystals. The optical method was shown to be effective for indication of secondary Bi-rich phases on the surface of (M$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{3}$)$\text{}_{m}$(CuO$\text{}_{2}$)$\text{}_{n}$ samples

Graded-gap AlxGa1-x as X-ray detector with collected charge multiplication

An increase in sensitivity of the graded-gap AlxGa1-As-x/GaAs X-ray detectors is achieved using multiplication of charge generated in a detector body. A thin n-GaAs layer was grown on a narrow-gap side of the AlxGa1-As-x structure. This layer is used as a photoconductor. The multiplication of the charge injected from the graded-gap structure to the photoconductive n-GaAs layer exceeds a few hundred times. This sensitive structure was tested as a detector of single alpha particles (from an Am-241 source)

Non-uniformly doped graded-gap Al(x)Ga(l-)xAs X-ray detectors with high photovoltaic response

Graded-gap AlxGa1-xAs/GaAs X-ray detectors with photovoltaic response have been designed and fabricated. A charge collection efficiency of 100% has been achieved in an AlxGa1-xAs layer with a thickness of 15 mum without application of any bias voltage to the layer. Experimentally, the measured sensitivity achieves 0.9 A/W. Amplification of the photocurrent takes place in the thin (15 mum) AlxGa1-xAs layer, and an efficiency of 5 x 10(5) V/W is attained at an absorbed power of 10(-7) W. The possibilities of using the new detectors for observation of X- ray images are considered

Optical response of the graded-gap AlxGa1-xAs X-ray detector

It has been observed that only a part of the AlxGa1-xAs graded- gap layer with the energy gap gradient g gt 20 eV/cm is active as a X-ray luminescence source. The thickness of the active layer is 30-50 mum. To increase the detectors optical response efficiency, the following methods are proposed and tested: 1. Reflection of the X-ray luminescence light, generated in the bulk AlxGa1-xAs layer, inside the total reflection angle theta; 2. Optical stimulation of the electron-hole radiative recombination

Growth of oxide buffer layers and YBCO films on various substrates by pulsed injection CVD

Bilayers composed from a YSZ or CeO2 buffer layer and a YBCO film were in situ grown on monocrystalline sapphire, MgO, silicon, vicinally polished sapphire and MgO substrates by single source pulsed injection CVD. Zr, Ce, Y, Ba and Cu 2,2,6,6-tetramethyl-3,5-heptandionates dissolved in organic solvent were used for film deposition. CeO2/YBCO bilayers on sapphire were grown epitaxially and exhibited critical current densities up to 106 A/cm2 at 77 K. YSZ and CeO2 buffer layers on MgO substrates did not improved the properties of YBCO layers compared with YBCO films deposited directly on MgO surface ; however, interesting microstructural properties of these heterostructures were found. Homogeneous YSZ films were also deposited on large Si substrates (3 inches in diameter)