Load-cell based characterization system for a "Violin-Mode" shadow-sensor in advanced LIGO suspensions

The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an Advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which 40 kg test-mass/mirrors are each suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation, and a rectangular silicon photodiode detector, which, together, were to bracket the fibre under test. The aim was to detect transverse Violin-Mode resonances in the suspension fibres. Part of the testing procedure involved tensioning a silica fibre sample, and translating it transversely through the illuminating NIR beam, so as to measure the DC responsivity of the detection system to fibre displacement. However, an equally important part of the procedure, reported here, was to keep the fibre under test stationary within the beam, whilst trying to detect low-level AC Violin-Mode resonances excited on the fibre, in order to confirm the primary function of the sensor. Therefore, a tensioning system, incorporating a load-cell readout, was built into the test fibre’s holder. The fibre then was excited by a signal generator, audio power amplifier, and distant loudspeaker, and clear resonances were detected. A theory for the expected fundamental resonant frequency as a function of fibre tension was developed, and is reported here, and this theory was found to match closely the detected resonant frequencies as they varied with tension. Consequently, the resonances seen were identified as being proper Violin-Mode fundamental resonances of the fibre, and the operation of the Violin-Mode detection system was validated

An AC modulated Near InfraRed gain calibration system for a "Violin-Mode" transimpedance amplifier, intended for advanced LIGO suspensions

The background to this work was a prototype shadow sensor, which was designed for retro-fitting to an Advanced LIGO (Laser Interferometer Gravitational wave Observatory) test-mass/mirror suspension, in which a 40 kg test-mass/mirror is suspended by four approximately 600 mm long by 0.4 mm diameter fused-silica suspension fibres. The shadow sensor comprised a LED source of Near InfraRed (NIR) radiation, and a ‘tall-thin’ rectangular silicon photodiode detector, which together were to bracket the fibre under test. The photodiode was positioned so as to be sensitive (primarily) to transverse ‘Violin-Mode’ vibrations of such a fibre, via the oscillatory movement of the shadow cast by the fibre, as this moved across the face of the detector. In this prototype shadow sensing system the photodiode was interfaced to a purpose-built transimpedance amplifier, this having both AC and DC outputs. A quasi-static calibration was made of the sensor’s DC responsivity, i.e., incremental rate of change of output voltage versus fibre position, by slowly scanning a fused-silica fibre sample transversely through the illuminating beam. The work reported here concerns the determination of the sensor’s more important AC (Violin-Mode) responsivity. Recognition of the correspondence between direct AC modulation of the source, and actual Violin-Mode signals, and of the transformative rôle of the AC/DC gain ratio for the amplifier, at any modulation frequency, f, resulted in the construction of the AC/DC calibration source described here. A method for determining in practice the transimpedance AC/DC gain ratio of the photodiode and amplifier, using this source, is illustrated by a specific numerical example, and the gain ratio for the prototype sensing system is reported over the frequency range 1 Hz–300 kHz. In fact, a maximum DC responsivity of 1.26 kV.m-1 was measured using the prototype photodiode sensor and amplifier discussed here. Therefore, the measured AC/DC transimpedance gain ratio of 922.5 for this sensor, at 500 Hz, translated into a maximum Violin-Mode (AC) responsivity of (1.16 0.05) MVm-1, at that frequency

A step-wise steerable source of illumination for low-noise "Violin-Mode" shadow sensors, intended for use in interferometric gravitational wave detectors

A steerable low-noise source of illumination is described for shadow-sensors having a displacement sensitivity of ∼100 pm (rms)/√Hz, at 500 Hz, over a measuring span of at least ±0.5 mm. These sensors were designed to detect lateral "Violin-Mode" resonances in the highly tensioned fused-silica suspension fibres of the test-masses/mirrors for the Advanced Laser Interferometer Gravitational Wave Observatory gravitational wave detectors. The shadow sensors—one intended for each of the four fibres in a suspension—comprised a source of Near InfraRed (NIR) radiation (emitter) and a differential shadow-displacement sensor (detector), these bracketing the fibre under test. The suspension fibres themselves were approximately 600 mm long by 0.4 mm in diameter, and when illuminated from the side, they cast narrow, vertical, shadows onto their respective detectors—these being located at an effective distance of 50 fibre diameters behind the axes of the fibres themselves. The emitter described here was designed to compensate for a significant degree of mechanical drift or creep over time in the mean position of its suspension fibre. This was achieved by employing five adjacent columns of 8 × miniature NIR LEDs (Light Emitting Diodes, λ = 890 nm), with one column being activated at a time. When used in conjunction with a "reverse Galilean" telescope, the LED sources allowed the collimated beam from the emitter to be steered azimuthally in fine angular increments (0.65◦), causing the fibre's shadow to move laterally, in a step-wise manner, across the plane of its facing detector. Each step in shadow position was approximately 0.23 mm in size, and this allowed the fibre's shadow to be re-centred, so as to bridge once again both elements of its photodiode detector—even if the fibre was off-centred by as much as ±0.5 mm. Re-centring allowed Violin-Mode vibrations of the fibre to be sensed once again as differential AC photocurrents, these flowing in anti-phase in the two elements of the "split-photodiode" detector. C 2016 AIP Publishing LLC

Search of the Orion spur for continuous gravitational waves using a loosely coherent algorithm on data from LIGO interferometers

We report results of a wideband search for periodic gravitational waves from isolated neutron stars within the Orion spur towards both the inner and outer regions of our Galaxy. As gravitational waves interact very weakly with matter, the search is unimpeded by dust and concentrations of stars. One search disk (A) is 6.87° in diameter and centered on 20h10m54.71s+33°33′25.29′′, and the other (B) is 7.45° in diameter and centered on 8h35m20.61s−46°49′25.151′′. We explored the frequency range of 50–1500 Hz and frequency derivative from 0 to −5×10−9  Hz/s. A multistage, loosely coherentsearch program allowed probing more deeply than before in these two regions, while increasing coherence length with every stage. Rigorous follow-up parameters have winnowed the initial coincidence set to only 70 candidates, to be examined manually. None of those 70 candidates proved to be consistent with an isolated gravitational-wave emitter, and 95% confidence level upper limits were placed on continuous-wave strain amplitudes. Near 169 Hz we achieve our lowest 95% C.L. upper limit on the worst-case linearly polarized strain amplitude h0 of 6.3×10−25, while at the high end of our frequency range we achieve a worst-case upper limit of 3.4×10−24 for all polarizations and sky locations

DNA marker identification of Rpv3 downy mildew resistance gene in seedless grape varieties

Table grapes are a valuable dietary product. Seedless grapes are in high demand among consumers. For this reason, the breeding of seedless varieties is one of the popular trends in modern viticulture, along with the production of environmentally friendly products. Downy mildew (Plasmopara viticola (Berk. & M.A. Curtis) Berl. & De Toni) is one of the most common fungal diseases of the grapevine. Most downy mildew resistant grape accessions belong to North American species like Vitis aestivalis Michx., V. berlandieri Planch., V. cinerea (Engelm. ex A. Gray) Engelm. ex Millard, V. riparia Michx., V. rupestris  Scheele, etc. The search for donors of resistance genes is an urgent task. Rpv3 is one of the most significant resistance genes from a number of North American grape varieties. The aim of this work is to identify the downy mildew resistance gene Rpv3 in seedless grape varieties by means of DNA-marker analysis. The grape varieties with rudimentary development of seed in berries and with North American species in the pedigree were chosen as the object of the study. The varieties “Dunavski lazur” and “Seyve Villard 12-375” with reference alleles were used as the positive control, while V. vinifera L. was used as the negative control. UDV305 and UDV737 DNA-markers were used in this study to identify the allelic type of the Rpv3 gene. The work was performed using the polymerase chain reaction. The reaction products were separated by capillary electrophoresis using the ABI Prism 3130 automatic genetic analyzer. Evaluation of the results was done using the GeneMapper and PeakScanner software. Functional alleles of the downy mildew resistance gene Rpv3 were revealed in grape  varieties “Kishmish zaporozhskiy”, “Lady Patricia”, “Remaily seedless”, “Pamyati Smirnova” and “Shayan”. Rpv3299-279, one of the seven known haplotypes, was identified in all the varieties. The pedigree analysis of the studied varieties indicated that the parental forms – “Seyve Villard” and “Seibel” hybrids – are presumably the donors of the gene. Grape accessions with the identified Rpv3 gene can be used in seedless varieties breeding as donors of resistance to downy mildew

Genetic diversity analysis of apricots from Dagestan using SSR markers

Background. This publication presents the results of a study into the genetic structure of apricot genotypes from Dagestan using the SSR genotyping technique. The importance of the study is seen in the still underexplored gene pool of Dagestani apricot at the genetic level. With this in view, an assessment of the Dagestani apricot genetic diversity, followed by an analysis of its genetic structure, is of theoretical and practical interest.Materials and methods. The study included 27 apricot genotypes of Dagestani origin: 9 advanced contemporary cultivars and hybrids, 15 seed selections and landraces, and 3 wild forms. Eight SSR markers were used for the genetic diversity analysis: H1-3, A1-91, H2-79, H1-26-2, H2-16, A1-17, RPPG1-032, and RPPG3-026.Results. The UPGMA and NJ dendrogram construction techniques revealed the genetic similarity among the Dagestani apricots, confirmed by a low level of cluster significance. The tendency towards setting apart the genotypes of hybrid origin (obtained from free pollination of introduced cultivars) from the locally selected cultivars was observed by comparing the results of Bayesian analysis and the K-means approach using the Structure and Statistica software. Such isolation is partial, being obviously affected by constant integration of new apricot genotypes into the local gene pool and its enrichment with new alleles at the genetic level.Conclusion. The contemporary assortment of apricots in Dagestan was formed on the basis of both the local autochthonous gene pool and Central Asian and European cultivars introduced into this area. The obtained data will enrich the knowledge about the genetic diversity of apricots in Dagestan and serve as the platform for further studies into the florigenetic links of the North Caucasus with other regions

DNA-marker based identification of the RPV3 gene determining downy mildew resistance in grapevines

Downy mildew is one of the most common fungal diseases of the vine, caused by Plasmopara viticola. An effective way to control the spread of the pathogen is to cultivate resistant varieties. Cultivars of Vitis vinifera, being the basis of high-quality viticulture, practically do not possess genetic resistance to P. viticola, so screening for resistance donors is an important stage in breeding. One of the major resistance loci to downy mildew, the Rpv3 gene, was identified in the genotype of a complex interspecific hybrid of grapes Bianca. Later, it was found that this gene had seven haplotypes of resistance inherited from North American grape species, and that it was possible to identify the allelic status of the gene using DNA-markers UDV305, UDV737. However, only two haplotypes can be combined in one diploid form. To determine the Rpv3 gene in the grape gene pool we, using these markers, studied 35 different genotypes of grapevines, most of which are interspecies cultivars. Three varieties with known allelic status of the Rpv3 gene (Dunavski lazur, Noah, Seyve Villard 12-375) were included in the study as reference genotypes. The genotypes were studied through polymerase chain reaction with separation of amplification products by capillary electrophoresis in automatic genetic analyzer ABI Prism 3130. In the studied grape cultivars DNA marker analysis indentified the Rpv3 gene in sixteen genotypes of interspecific origin, including haplotype Rpv3299-279 found in twelve varieties, Rpv3321-312 – in three, and haplotype Rpv3null-271 – in one variety. Seyve Villard 12-375 turned out to be the donor of resistance gene in the most of the genotypes carrying Rpv3 in this study. The obtained data can be useful in selection of mildew resistant grape varieties and screening for hybridization pairs

Identification of apple genes <i>Md-Exp7</i> and <i>Md-PG1</i> alleles in advanced selections resistant to scab

The creation of apple varieties with a high level of flesh firmness and long shelf life is one of the important goals in breeding. Among the genes controlling these traits, the role of the endogenous ethylene biosynthesis control gene, Md-ACS1, the expansin gene, Md-Exp7, and the polygalacturonase gene, Md-PG1, has been established. The use of DNA marker analysis to solve problems in breeding for fruit quality traits allows one not only to track several target genes simultaneously, but also to cull plants with undesirable alleles at the early stages of development. In order to select complex donors of breeding traits, molecular genetic identification of the genes that determine the quality traits of apple fruits Md-Exp7 and Md-PG1 was performed in 256 breeding selections carrying the scab resistance gene Rvi6 and valuable allelic variants of the Md-ACS-1 gene, which determines the endogenous synthesis of ethylene in fruits: 90 samples with the Md-ACS1 allele (2/2) and 166 samples with Md-ACS1 (1/2). As a result of the study, an allelic combination for the Md-Exp7 and Md-PG1 genes was established. Analysis of the parental cultivars (Renet Simirenko, Modi, Smeralda, Renoir, Fulzhion and Granny Smith) used to obtain hybrid selections revealed three alleles 198, 202, 214 bp according to the DNA marker of the Md-Exp7 gene. The SSR marker for the Md-PG1 gene amplified three alleles (289, 292, 298 bp) on the abovementioned cultivars. Within the 256 breeding selections samples that have the most priority for breeding alleles of the desired genes in combination with the Rvi6 gene and/or with selection-priority allelic variants of the Md-ACS-1 gene were identified. Of the most valuable for breeding, 46 accessions carrying the combination Md-Exp7 (202:202) + Md-ACS1 (2/2) were distinguished. Hybrids with alleles Md-PG1 (292:292) + Md-ACS1 (2/2) are also most valuable for use in breeding and as donors of selection-valuable alleles; 21 samples were identified. Accessions with a complex of breeding-valuable target alleles are valuable complex donors, as well as valuable breeding material for creating varieties with improved fruit quality characteristics and scab resistance

Nomenclatural standards and genetic certificates for apple-tree cultivars developed at the North Caucasian Federal Scientific Center of Horticulture, Viticulture, wine-making

Background. The development of genetic certificates and nomenclatural standards for newly released cultivars of Malus domestica Borkh. (apple tree) ensures an opportunity to preserve the original and authentic genetic and morphological information on domestic cultivars promising for the south of Russia. The purpose of this study was to develop genetic certificates and nomenclatural standards for 7 apple-tree cultivars developed at the North Caucasian Federal Scientific Center of Horticulture, Viticulture, Wine-making (NCFSCHVW), five of which were released jointly with the All-Russian Research Institute of Fruit Crop Breeding (VNIISPK).Materials and methods. The materials included apple-tree cultivars resistant or immune to scab (Venturia inaequalis (Cooke) G. Winter) from the NCFSCHVW collection stock. Conventional herbarization and DNA fingerprinting methods were used. For cultivar certification, an improved technique of DNA sampling and 12 microsatellite markers were applied.Results. Unique DNA profile certificates and nomenclatural standards were produced for 7 apple-tree cultivars: ‘Vasilisa’, ‘Karmen’, ‘Krasny Yantar’, ‘Soyuz’ and ‘Rassvet’ (with the Rvi6 gene) released jointly by the NCFSCHVW and VNIISPK, plus ‘Zolotoye Letneye’ and ‘Feya’ developed at the NCFSCHVW. The apple-tree herbarium specimens were placed for perpetual storage in the WIR Herbarium of the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR).Conclusion. The results obtained are promising for identification and authenticity verification of new domestic apple-tree cultivars during their reproduction and cultivation