Development of a HgCdTe photomixer and impedance matched GaAs FET amplifier

A research program for the development of a 10.6 micron HgCdTe photodiode/GaAs field effect transistor amplifier package for use at cryogenic temperatures (77k). The photodiode/amplifier module achieved a noise equivalent power per unit bandwidth of 5.7 times 10 to the 20th power W/Hz at 2.0 GHz. The heterodyne sensitivity of the HgCdTe photodiode was improved by designing and building a low noise GaAs field effect transistor amplifier operating at 77K. The Johnson noise of the amplifier was reduced at 77K, and thus resulted in an increased photodiode heterodyne sensitivity

Assessment of invasive muskrat Ondatra zibethicus distribution and impacts on ecosystems in Lithuania

Butautytė-Skyrienė, G., Paulauskas, A., Ulevičius, A

Growth, Characterization, and Electrochemical Properties of Doped n-Type KTaO_3 Photoanodes

The effects of compositionally induced changes on the semiconducting properties, optical response, chemical stability, and overall performance of KTaO_3 photoanodes in photoelectrochemical (PEC) cells have been investigated. Single crystals of n-type Ca- and Ba-doped KTaO_3 with carrier concentrations ranging from 0.45 to 11.5×10^(19) cm^(−3) were grown and characterized as photoanodes in basic aqueous electrolyte PEC cells. The PEC properties of the crystals, including the photocurrent, photovoltage, and flatband potential in contact with 8.5 M NaOH(aq) were relatively independent of whether Ca or Ba was used to produce the semiconducting form of KTaO_3. All of the Ca- or Ba-doped KTaO_3 single-crystal photoanodes were chemically stable in the electrolyte and, based on the open-circuit potential and the band-edge positions, were capable of unassisted photochemical H_2 and O_2 evolution from H_2O. The minority-carrier diffusion lengths values were small and comparable to the depletion region width. Photoanodic currents were only observed for photoanode illumination with light above the bandgap (i.e., λ<340 nm). The maximum external quantum yield occurred at λ=255 nm (4.85 eV), and the depletion width plus the minority-carrier diffusion length ranged from 20 to 65 nm for the various KTaO_3-based photoanode materials

Sensitivity of non-target groups of invertebrates to cypermethrin

Agrogenic pollution with pyrethroid insecticides has been impacting the structure of populations of terrestrial invertebrates, causing decline in their taxonomic diversity and tolerance to critical values of environmental factors. In a laboratory experiment, we evaluated the sensitivity of 46 non-target invertebrate species to cypermethrin. In most examined species, we observed correlation between the body parameters (length and weight of body) and tolerance to this insecticide. We determined that the greater body size of the invertebrates, the better their tolerance to cypermethrin. Differences in LD50 were the highest for groups of invertebrates with the body weight of 1.0–3.9 mg (1.9 ± 0.5 g/ha) and 16.0–63.9 mg (16.4 ± 3.2 g/ha). We observed a relashionship between the trophic specialization and sensitivity to the insecticide in phytophages and zoophages. Average LD50 values for phytophages were 2.1 ± 0.5 g/ha, much lower than for zoophages – 15.6 ± 3.3 g/ha. Among zoophages, the greatest tolerance to cypermethrin was demonstrated by ground beetles Carabus coriaceus L., Pterostichus niger (Schall.), P. melanarius (Ill.), Pseudoophonus rufipes (De Geer), and earwigs Forficula auricularia L. Analysis of various taxonomic groups of insects revealed the parameter to be 24.00 ± 4.66 for Carabidae, 8.60 ± 2.72 for Formicidae, and 0.23 ± 0.08 for Staphylinidae. Among the taxonomic groups we studied, the most sensitive to cypermethrin (LD50 = 0.002–0.99 g/ha) were Philonthus decorus (0.0029), Ph. rectangulus (0.0035), Ophonus rufibarbis (0.121), Oxytelus sculptus (0.124), Myrmica ruginodis (0.39), Aleochara lanuginosa (0.49), Carabus granulatus (0.51), Oxythyrea funesta (0.52), Tachinus signatus (0.55), Cixiidae sp. (0.56), Lygus pratensis (0.56), Carabus convexus (0.71), and C. hortensis (0.83). Lower sensitivity to cypermethrin (LD50 = 1.00–9.99 g/ha) was seen in Lasius fuliginosus (1.05), Pyrrhocoris apterus (1.28), Chortippus sp. 2 (1.96), Rhyparochromus phoeniceus (2.24), Phosphuga atrata (2.25), Chironomus plumosus (2.58), Labia minor (2.86), Graphosoma italicum (2.86), Hister fenestus (3.39), Cylindroiulus truncorum (3.61), Opilio saxatilis (3.71), Chortippus sp. 1 (3.94), Epaphius secalis (4.54), Lasius niger (4.77), Silpha carinata (4.84), Aphodius foetens (4.94), Porcellio laevis (5.68), Coreus marginatus (6.50), Leistus ferrugineus (7.39), and Lasius alienus (9.73). The most tolerant to cypermethrin (LD50 = 10.00–108.00 g/ha) were Calathus fuscipes (12.14), Limodromus assimilis (12.22), Trochosa terricola (12.55), Lithobius forficatus (13.98), Calathus ambiguus (20.85), Nebria brevicollis (23.20), Ponera coarctata (27.04), Megaphyllum sp. (29.01), Pseudoophonus rufipes (41.75), Pterostichus melanarius (45.78), P. niger (58.29), Forficula auricularia (80.57), and Carabus coriaceus (107.71). The differences we found in tolerance to cypermethrin ranged 100,000 times. This evidences the necessity of further research of taxonomic differences in tolerance of invertebrates to cypermethrin

Genetic variability of raccoon dogs and their impacts on the environment in Lithuania

Pūraitė, I., Griciuvienė, L., Paulauskas, A., Sruoga, A., Gedminas, V., Butkauskas, D

Development of the (d,n) proton-transfer reaction in inverse kinematics for structure studies

Transfer reactions have provided exciting opportunities to study the structure of exotic nuclei and are often used to inform studies relating to nucleosynthesis and applications. In order to benefit from these reactions and their application to rare ion beams (RIBs) it is necessary to develop the tools and techniques to perform and analyze the data from reactions performed in inverse kinematics, that is with targets of light nuclei and heavier beams. We are continuing to expand the transfer reaction toolbox in preparation for the next generation of facilities, such as the Facility for Rare Ion Beams (FRIB), which is scheduled for completion in 2022. An important step in this process is to perform the (d,n) reaction in inverse kinematics, with analyses that include Q-value spectra and differential cross sections. In this way, proton-transfer reactions can be placed on the same level as the more commonly used neutron-transfer reactions, such as (d,p), (9Be,8Be), and (13C,12C). Here we present an overview of the techniques used in (d,p) and (d,n), and some recent data from (d,n) reactions in inverse kinematics using stable beams of 12C and 16O.Comment: 9 pages, 4 figures, presented at the XXXV Mazurian Lakes Conference on Physics, Piaski, Polan

Borrelia burgdorferi sensu lato in Ixodes ricinus ticks collected from migratory birds in Southern Norway

<p>Abstract</p> <p>Background</p> <p><it>Borrelia burgdorferi </it>sensu lato (s.l.) are the causative agent for Lyme borreliosis (LB), the most common tick-borne disease in the northern hemisphere. Birds are considered important in the global dispersal of ticks and tick-borne pathogens through their migration. The present study is the first description of <it>B. burgdorferi </it>prevalence and genotypes in <it>Ixodes ricinus </it>ticks feeding on birds during spring and autumn migration in Norway.</p> <p>Methods</p> <p>6538 migratory birds were captured and examined for ticks at Lista Bird Observatory during the spring and the autumn migration in 2008. 822 immature <it>I. ricinus </it>ticks were collected from 215 infested birds. Ticks were investigated for infection with <it>B. burgdorferi </it>s.l. by real-time PCR amplification of the 16S rRNA gene, and <it>B. burgdorferi </it>s.l. were thereafter genotyped by melting curve analysis after real-time PCR amplification of the <it>hbb </it>gene, or by direct sequencing of the PCR amplicon generated from the <it>rrs </it>(16S)-<it>rrl </it>(23S) intergenetic spacer.</p> <p>Results</p> <p><it>B. burgdorferi </it>s.l. were detected in 4.4% of the ticks. The most prevalent <it>B. burgdorferi </it>genospecies identified were <it>B. garinii </it>(77.8%), followed by <it>B.valaisiana </it>(11.1%), <it>B. afzelii </it>(8.3%) and <it>B. burgdorferi </it>sensu stricto (2.8%).</p> <p>Conclusion</p> <p>Infection rate in ticks and genospecies composition were similar in spring and autumn migration, however, the prevalence of ticks on birds was higher during spring migration. The study supports the notion that birds are important in the dispersal of ticks, and that they may be partly responsible for the heterogeneous distribution of <it>B. burgdorferi </it>s.l. in Europe.</p

Cascaded Multilevel Inverter-Based Asymmetric Static Synchronous Compensator of Reactive Power

The topology of the static synchronous compensator of reactive power for a low-voltage three-phase utility grid capable of asymmetric reactive power compensation in grid phases has been proposed and analysed. It is implemented using separate, independent cascaded H-bridge multilevel inverters for each phase. Every inverter includes two H-bridge cascades. The first cascade operating at grid frequency is implemented using thyristors, and the second one—operating at high frequency is based on the high-speed MOSFET transistors. The investigation shows that the proposed compensator is able to compensate the reactive power in a low-voltage three-phase grid when phases are loaded by highly asymmetrical reactive loads and provides up to three times lower power losses in the compensator as compared with the situation when the compensator is based on the conventional three-level inverters implemented using IGBT transistors.publishedVersio