Deuteron photo-disintegration with polarised photons in the energy range 30 - 50 MeV

The reaction d(\vec\gamma,np) has been studied using the tagged and polarised LADON gamma ray beam at an energy 30 - 50 MeV to investigate the existence of narrow dibaryonic resonances recently suggested from the experimental measurements in a different laboratory. The beam was obtained by Compton back-scattering of laser light on the electrons of the storage ring ADONE. Photo-neutron yields were measured at five neutron angle \vartheta_n = 22, 55.5, 90, 125 and 157 degrees in the center of mass system.Our results do not support the existence of such resonances.Comment: 16 pages, Latex, 22 figures, 1 table. Nucl. Phys. A to appea

Modeling Micro-Porous Surfaces for Secondary Electron Emission Control to Suppress Multipactor

This work seeks to understand how the topography of a surface can be engineered to control secondary electron emission (SEE) for multipactor suppression. Two unique, semi-empirical models for the secondary electron yield (SEY) of a micro-porous surface are derived and compared. The first model is based on a two-dimensional (2D) pore geometry. The second model is based on a three-dimensional (3D) pore geometry. The SEY of both models is shown to depend on two categories of surface parameters: chemistry and topography. An important parameter in these models is the probability of electron emissions to escape the surface pores. This probability is shown by both models to depend exclusively on the aspect ratio of the pore (the ratio of the pore height to the pore diameter). The increased accuracy of the 3D model (compared to the 2D model) results in lower electron escape probabilities with the greatest reductions occurring for aspect ratios less than two. In order to validate these models, a variety of micro-porous gold surfaces were designed and fabricated using photolithography and electroplating processes. The use of an additive metal-deposition process (instead of the more commonly used subtractive metal-etch process) provided geometrically ideal pores which were necessary to accurately assess the 2D and 3D models. Comparison of the experimentally measured SEY data with model predictions from both the 2D and 3D models illustrates the improved accuracy of the 3D model. For a micro-porous gold surface consisting of pores with aspect ratios of two and a 50% pore density, the 3D model predicts that the maximum total SEY will be one. This provides optimal engineered surface design objectives to pursue for multipactor suppression using gold surfaces

ТЕНДЕНЦІЯ ПОШИРЕННЯ ТРАНСГЕННИХ РОСЛИН У 2019-2021 РОКАХ

The achievement of modern biotechnology, in particular genetic engineering in crop production, provides not only the possibility of increasing production, but also more efficient use of natural resources and reduces the negative impact on the environment. Recent publications indicate the widespread distribution of genetically modified (GM) agricultural crops in the world that are currently in commercial use, research and development. All over the world, the most cultivated GM crops are cotton, soybeans, corn, and rapeseed, and the area under these biotechnological crops continues to grow every year. However, the analysis of publicly available sources of information revealed the risks of negative effects of GMOs on human and animal bodies, as well as on the environment and biodiversity. The article analyzes the results of research on the presence of GM ingredients in plant raw materials, processing products, and feed for productive and non-productive animals for the period 2019-2021. The study was conducted by the polymerase chain reaction method in real time (PCR-RF), according to DSTU ISO 21569:2008 (ISO 21569:2005, IDT), and DSTU ISO 21571:2008 (ISO 21571:2005, IDT). In the studied samples were detected target sequences of the promoter p35S CaMV (cauliflower mosaic virus), promoter p34S FMV, terminator NOS (T-NOS) T1 of the Agrobacterium tumefaciens plasmid, genes Pat, EPSPS, Cry 3A. Transgenic plants are present in circulation in the agricultural market of Ukraine, and the area under their crops is increasing. The largest number of GM plants was found in samples of rapeseed, soybeans, and feed for productive and non-productive animals. There was a tendency for an increase in the number of transgenic plants in tested samples. During rapeseed research in 2019, the number of positive samples was 6.5%, in 2020 – 7.4%, and in 2021 – 14.3%. When studying soybeans in 2019, the number of positive samples was 6.7%, in 2020 – 16.7%, and in 2021 – 18.2%. GM ingredients were also found in feed for productive and non-productive animals. In 2020 16.7% of compound feed for poultry were positive, while in 2021 there were no samples for research. As for feeds for non-productive animals, during 2019–2020 there were no detected positive samples, while in 2021 the number of positive samples was 12%.Досягнення сучасної біотехнології, зокрема генної інженерії у рослинництві, дає не тільки можливість вирішення збільшення виробництва продукції, але й більш ефективного використовування природних ресурсів і зменшення негативного впливу на довкілля. Останні публікації вказують на широке розповсюдження генетично модифікованих (ГМ) сільськогосподарських культур у світі, які нині перебувають у комерційному використанні, дослідженнях та розробках. У всьому світі найбільше культивуються ГМ - бавовна, соя, кукурудза та ріпак, і площі під ці біотехнологічні культури продовжують щороку зростати. Однак, при аналізі загальнодоступних джерел інформації виявлено ризики негативного впливу ГМО на організм людини і тварин та на довкілля і біорізноманіття. У статті проведено аналіз результатів досліджень щодо наявності ГМ-інгредієнтів в рослинній сировині, продуктах переробки, кормах для продуктивних і непродуктивних тварин тощо за період 2019-2021 рр. Дослідження проводили методом полімеразно-ланцюгової реакції в реальному часі (ПЛР-РЧ), згідно з ДСТУ ISO 21569:2008 (ISO 21569:2005, IDT), ДСТУ ISO 21571:2008 (ISO 21571:2005, IDT). У дослідних зразках виявляли цільові послідовності промотора р35S CaMV (вірусу мозаїки цвітної капусти), промотора р34S FMV, термінатора NOS (T-NOS) T1 плазміди Agrobacterium tumefaciens, генів Pat, EPSPS, Cry 3A. Трансгенні рослини присутні в обігу на аграрному ринку України і площі під їх посіви збільшуються. Найбільше ГМ-рослин виявлено у зразках ріпаку, бобах сої, кормах для продуктивних і непродуктивних тварин. Встановлено тенденцію до збільшення кількості трансгенних рослин у дослідних зразках. При дослідженні ріпаку у 2019 році кількість позитивних проб становила 6,5 %, у 2020 р. – 7,4 %, у 2021 р. – 14,3 %. При дослідженні сої у 2019 р. кількість позитивних проб становила 6,7 %, у 2020 р. – 16,7, %, у 2021 р. – 18,2 %. При дослідженні кормів для продуктивних і непродуктивних тварин теж виявлено ГМ-інгредієнти. При дослідженні комбікормів для птиці у 2020 році кількість позитивних зразків становила 16,7%, тоді як у 2021 р. зразків на дослідження не було. Щодо кормів для непродуктивних тварин, то упродовж 2019-2020 рр. не було виявлено жодного позитивного зразка, тоді як у 2021 р. кількість позитивних зразків становила 12 %

Mobility of Taxol in Microtubule Bundles

Mobility of taxol inside microtubules was investigated using fluorescence recovery after photobleaching (FRAP) on flow-aligned bundles. Bundles were made of microtubules with either GMPCPP or GTP at the exchangeable site on the tubulin dimer. Recovery times were sensitive to bundle thickness and packing, indicating that taxol molecules are able to move laterally through the bundle. The density of open binding sites along a microtubule was varied by controlling the concentration of taxol in solution for GMPCPP samples. With > 63% sites occupied, recovery times were independent of taxol concentration and, therefore, inversely proportional to the microscopic dissociation rate, k_{off}. It was found that 10*k_{off} (GMPCPP) ~ k_{off} (GTP), consistent with, but not fully accounting for, the difference in equilibrium constants for taxol on GMPCPP and GTP microtubules. With < 63% sites occupied, recovery times decreased as ~ [Tax]^{-1/5} for both types of microtubules. We conclude that the diffusion of taxol along the microtubule interior is hindered by rebinding events when open sites are within ~7 nm of each other.Comment: pre print forma

The Superconducting TESLA Cavities

The conceptional design of the proposed linear electron-positron collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with an accelerating gradient of Eacc >= 25 MV/m at a quality factor Q0 > 5E+9. The design goal for the cavities of the TESLA Test Facility (TTF) linac was set to the more moderate value of Eacc >= 15 MV/m. In a first series of 27 industrially produced TTF cavities the average gradient at Q0 = 5E+9 was measured to be 20.1 +- 6.2 MV/m, excluding a few cavities suffering from serious fabrication or material defects. In the second production of 24 TTF cavities additional quality control measures were introduced, in particular an eddy-current scan to eliminate niobium sheets with foreign material inclusions and stringent prescriptions for carrying out the electron-beam welds. The average gradient of these cavities at Q0 = 5E+9 amounts to 25.0 +- 3.2 MV/m with the exception of one cavity suffering from a weld defect. Hence only a moderate improvement in production and preparation techniques will be needed to meet the ambitious TESLA goal with an adequate safety margin. In this paper we present a detailed description of the design, fabrication and preparation of the TESLA Test Facility cavities and their associated components and report on cavity performance in test cryostats and with electron beam in the TTF linac. The ongoing R&D towards higher gradients is briefly addressed.Comment: 45 pages (Latex), 39 figures (Encapsulated Postscript), 53 Author

Measuring heat leak with a heatmeter

The heatmeter or more precisely the heatflowmeter is a device based on thermal conductivity measuring techniques. It consists of a thermal conducting body between two thermometers, with provisions for thermal connections and calibration. The paper describes the design, construction details, calibration and performance of one such heatmeter for use with heat reservoirs at either 4.2 K or 78 K. Near 4.2 K it has a sensitivity of 10 ..mu..W and requires less than a minute to reach steady state. Near 78 K its sensitivity is 10 MW and requires 25 minutes to reach steady state

Argonne National Laboratory Reports

This report describes logic programming approaches to two graph theoretical problems relevant to reactor and logic circuit analysis: those of cut-set verification and subsystem detection