The morphological and compositional changes of bimetallic Ti/Al thin film induced by ultra-short laser pulses

Results regarding morphological and compositional changes of bimetallic thin film (BMTF), composed of aluminium (Al) and titanium (Ti) nano-layers, by single fs laser pulses, are presented. Laser irradiation was conducted in the air with focused, linearly polarized laser pulses, the duration being 300 fs, wavelength 515 nm, and pulse energy up to 1.2μJ. Effects of the variations of the pulse energy on the changes were studied. In the experiment, single pulse energy values from 0.03 to 0.08 μ J caused ablation–photomechanical spallation of the upper part of BMTF layer from the Si substrate, without ablation of the whole film. Irradiation at higher pulse energies gradually removed the whole BMTF and even a part of the Si substrate. We explained the influence of different electron–phonon dynamics, in the case of multilayered thin films composed of Al and Ti, on BMTF ablation. Damage/ablation threshold, which is minimal pulse energy/fluence sufficient for starting ablation, was calculated. Graphic abstract: [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature

Quantum bath suppression in a superconducting circuit by immersion cooling

Quantum circuits interact with the environment via several temperature-dependent degrees of freedom. Multiple experiments to-date have shown that most properties of superconducting devices appear to plateau out at T ≈ 50 mK – far above the refrigerator base temperature. This is for example reflected in the thermal state population of qubits, in excess numbers of quasiparticles, and polarisation of surface spins – factors contributing to reduced coherence. We demonstrate how to remove this thermal constraint by operating a circuit immersed in liquid 3He. This allows to efficiently cool the decohering environment of a superconducting resonator, and we see a continuous change in measured physical quantities down to previously unexplored sub-mK temperatures. The 3He acts as a heat sink which increases the energy relaxation rate of the quantum bath coupled to the circuit a thousand times, yet the suppressed bath does not introduce additional circuit losses or noise. Such quantum bath suppression can reduce decoherence in quantum circuits and opens a route for both thermal and coherence management in quantum processors

Reflection-enhanced gain in traveling-wave parametric amplifiers

The operating principle of traveling-wave parametric amplifiers is typically understood in terms of the standard coupled mode theory, which describes the evolution of forward propagating waves without any reflections, i.e., for perfect impedance matching. However, in practice, superconducting microwave amplifiers are unmatched nonlinear finite-length devices, where the reflecting waves undergo complex parametric processes, not described by the standard coupled mode theory. Here, we present an analytical solution for the TWPA gain, which includes the interaction of reflected waves. These reflections result in corrections to the well-known results of the standard coupled mode theory, which are obtained for both three-wave and four-wave mixing processes. Due to these reflections, the gain is enhanced and unwanted nonlinear phase modulations are suppressed. Predictions of the model are experimentally demonstrated on two types of unmatched TWPA, based on coplanar waveguides with a central wire consisting of (i) a high kinetic inductance superconductor, and (ii) an array of 2000 Josephson junctions

Tunneling through a multigrain system: deducing the sample topology from the nonlinear conductance

We study a current transport through a system of a few grains connected with tunneling links. The exact solution is given for an arbitrarily connected double-grain system with a shared gate in the framework of the orthodox model. The obtained result is generalized for multigrain systems with strongly different tunneling resistances. We analyse the large-scale nonlinear conductance and demonstrate how the sample topology can be unambiguously deduced from the spectroscopy pattern (differential conductance versus gate-bias plot). We present experimental data for a multigrain sample and reconstruct the sample topology. A simple selection rule is formulated to distinguish samples with spectral patterns free from spurious disturbance caused by recharging of some grains nearby. As an example, we demonstrate experimental data with additional peaks in the spectroscopy pattern, which can not be attributed to coupling to additional grains. The described approach can be used to judge the sample topology when it is not guaranteed by fabrication and direct imaging is not possible.Comment: 13 pages (including 8 figures

Riistaeläinten populaatioiden dynamiikka Pohjois-Euroopassa: tiivistelmä : 7. kansainvälinen symposium. 24. – 28. Syyskuuta

We have studied Black Grouse population abundance and its dynamics in large regions of North-Europe and Urals’ taiga (Finland, Russian Karelia, Murmansk, Arhangel, Kirov and Komi regions and). The data is based on Winter Track Counts (WTC, Priklonski, 1973), where all grouse sightings are recorded. We also studied the longterm Black Grouse abundance changes in Russian and Belarus Natural Reserves (by “Chronical of Natural” Programme, including summer counts of forest grouses): Pinezhsky, Pechoro-Ilychskiy, National Park "Mechera", Nature Reserve "Kivach", "Bryansk Forest", Kostomuksha Nature Reserve Volzhsko-Kamsky National Nature Biosphere Reserve and Visimskiy State Nature Reserves. The highest and most stable abundances of Black Grouse were recorded from East Fennoscandia (Karelia – 3.6 birds per 10 km; Finland – 4.4, coefficient of variation – 12% and 27%, respectively), whereas in the Murmansk and Arkhangelsk Regions and Komi republic, e.g. the species abundance indices were 0.5, 2.5 and 1.1 birds per 10 km, respectively. The “Peak” and minimal abundance years do not concur in different regions of north-European taiga. In Komi in the period from 2001 to 2013, the number of the black grouse declined twice, in Arhangel in the period 30 years – decreased fivefold. In Tatarstan Republic (Volzhsko-Kamsky National Nature Biosphere Reserve) after 1980 abundance decreased rapidly and at last 10 tears – disappeared. In Central Siberia BG are small in numbers and rare. The data suggest Black Grouse abundance varies significantly across Northern Eurasia and among years. One may presume there are some factors acting in different directions: towards convergence and towards divergence of the trends.Peer reviewe

Challenges and science-based implications for modern management and conservation of European ungulate populations

Wildlife management systems face growing challenges to cope with increasingly complex interactions between wildlife populations, the environment and human activities. In this position statement, we address the most important issues characterising current ungulate conservation and management in Europe. We present some key points arising from ecological research that may be critical for a reassessment of ungulate management in the future. Ecosystem . Population sustainability . Science-basedmanagement .Wildlifemanagement .Adaptive managemen

Pro-apoptotic and antiproliferative activity of human KCNRG, a putative tumor suppressor in 13q14 region

Deletion of 13q14.3 and a candidate gene KCNRG (potassium channel regulating gene) is the most frequent chromosomal abnormality in B-cell chronic lymphocytic leukemia and is a common finding in multiple myeloma (MM). KCNRG protein may interfere with the normal assembly of the K+ channel proteins causing the suppression of Kv currents. We aimed to examine possible role of KCNRG haploinsufficiency in chronic lymphocytic leukemia (CLL) and MM cells. We performed detailed genomic analysis of the KCNRG locus; studied effects of the stable overexpression of KCNRG isoforms in RPMI-8226, HL-60, and LnCaP cells; and evaluated relative expression of its transcripts in various human lymphomas. Three MM cell lines and 35 CLL PBL samples were screened for KCNRG mutations. KCNRG exerts growth suppressive and pro-apoptotic effects in HL-60, LnCaP, and RPMI-8226 cells. Direct sequencing of KCNRG exons revealed point mutation delT in RPMI-8226 cell line. Levels of major isoform of KCNRG mRNA are lower in DLBL lymphomas compared to normal PBL samples, while levels of its minor mRNA are decreased across the broad range of the lymphoma types. The haploinsufficiency of KCNRG might be relevant to the progression of CLL and MM at least in a subset of patients

Measurement of quark- and gluon-like jet fractions using jet charge in PbPb and pp collisions at 5.02 TeV

The momentum-weighted sum of the electric charges of particles inside a jet, known as jet charge, is sensitive to the electric charge of the particle initiating the parton shower. This paper presents jet charge distributions in root sNN = 5.02 TeV lead-lead (PbPb) and proton-proton (pp) collisions recorded with the CMS detector at the LHC. These data correspond to integrated luminosities of 404 mu b(-1)and 27.4 pb(-1)for PbPb and pp collisions, respectively. Leveraging the sensitivity of the jet charge to fundamental differences in the electric charges of quarks and gluons, the jet charge distributions from simulated events are used as templates to extract the quark- and gluon-like jet fractions from data. The modification of these jet fractions is examined by comparing pp and PbPb data as a function of the overlap of the colliding Pb nuclei (centrality). This measurement tests the color charge dependence of jet energy loss due to interactions with the quark-gluon plasma. No significant modification between different centrality classes and with respect to pp results is observed in the extracted quark- and gluon-like jet fractions.Peer reviewe