Graph editing to a fixed target

For a fixed graph H, the H-Minor Edit problem takes as input a graph G and an integer k and asks whether G can be modified into H by a total of at most k edge contractions, edge deletions and vertex deletions. Replacing edge contractions by vertex dissolutions yields the H-Topological Minor Edit problem. For each problem we show polynomial-time solvable and NP-complete cases depending on the choice of H. Moreover, when G is AT-free, chordal or planar, we show that H-Minor Edit is polynomial-time solvable for all graphs H

Proposal for a phonon laser utilizing quantum-dot spin states

We propose a nanoscale realization of a phonon laser utilizing phonon-assisted spin flips in quantum dots to amplify sound. Owing to a long spin relaxation time, the device can be operated in a strong pumping regime, in which the population inversion is close to its maximal value allowed under Fermi statistics. In this regime, the threshold for stimulated emission is unaffected by spontaneous spin flips. Considering a nanowire with quantum dots defined along its length, we show that a further improvement arises from confining the phonons to one dimension, and thus reducing the number of phonon modes available for spontaneous emission. Our work calls for the development of nanowire-based, high-finesse phonon resonators. © 2013 American Physical Society.A. K. acknowledges financial support from the SPINMET Project (FP7-PEOPLE-2009-IRSES). The work was supported by the ONR, DOE-BES DESC0004890, and NSF-ECCS. X. Hu also acknowledges support by the U.S. ARO and NSF-PIF. The work of V. N. G. was supported by the Spanish Ministry of Economy and Competitiveness under Project No. FIS2011-28851-C02-02.Peer Reviewe

Single-dopant resonance in a single-electron transistor

Single dopants in semiconductor nanostructures have been studied in great details recently as they are good candidates for quantum bits, provided they are coupled to a detector. Here we report coupling of a single As donor atom to a single-electron transistor (SET) in a silicon nanowire field-effect transistor. Both capacitive and tunnel coupling are achieved, the latter resulting in a dramatic increase of the conductance through the SET, by up to one order of magnitude. The experimental results are well explained by the rate equations theory developed in parallel with the experiment.Comment: 16 pages, 8 figure

Dynamic response of 1D bosons in a trap

We calculate the dynamic structure factor S(q,omega) of a one-dimensional (1D) interacting Bose gas confined in a harmonic trap. The effective interaction depends on the strength of the confinement enforcing the 1D motion of atoms; interaction may be further enhanced by superimposing an optical lattice on the trap potential. In the compressible state, we find that the smooth variation of the gas density around the trap center leads to softening of the singular behavior of S(q,omega) at Lieb-1 mode compared to the behavior predicted for homogeneous 1D systems. Nevertheless, the density-averaged response remains a non-analytic function of q and omega at Lieb-1 mode in the limit of weak trap confinement. The exponent of the power-law non-analyticity is modified due to the inhomogeneity in a universal way, and thus, bears unambiguously the information about the (homogeneous) Lieb-Liniger model. A strong optical lattice causes formation of Mott phases. Deep in the Mott regime, we predict a semi-circular peak in S(q,\omega) centered at the on-site repulsion energy, omega=U. Similar peaks of smaller amplitudes exist at multiples of U as well. We explain the suppression of the dynamic response with entering into the Mott regime, observed recently by D. Clement et al., Phys. Rev. Lett. v. 102, p. 155301 (2009), based on an f-sum rule for the Bose-Hubbard model.Comment: 24 pages, 11 figure

Phonon-induced decay of the electron spin in quantum dots

We study spin relaxation and decoherence in a GaAs quantum dot due to spin-orbit interaction. We derive an effective Hamiltonian which couples the electron spin to phonons or any other fluctuation of the dot potential. We show that the spin decoherence time $T_2$ is as large as the spin relaxation time $T_1$, under realistic conditions. For the Dresselhaus and Rashba spin-orbit couplings, we find that, in leading order, the effective magnetic field can have only fluctuations transverse to the applied magnetic field. As a result, $T_2=2T_1$ for arbitrarily large Zeeman splittings, in contrast to the naively expected case $T_2\ll T_1$. We show that the spin decay is drastically suppressed for certain magnetic field directions and values of the Rashba coupling constant. Finally, for the spin coupling to acoustic phonons, we show that $T_2=2T_1$ for all spin-orbit mechanisms in leading order in the electron-phonon interaction.Comment: 5 pages, 1 figur

SiGe quantum dots for fast hole spin Rabi oscillations

We report on hole g-factor measurements in three terminal SiGe self-assembled quantum dot devices with a top gate electrode positioned very close to the nanostructure. Measurements of both the perpendicular as well as the parallel g-factor reveal significant changes for a small modulation of the top gate voltage. From the observed modulations we estimate that, for realistic experimental conditions, hole spins can be electrically manipulated with Rabi frequencies in the order of 100MHz. This work emphasises the potential of hole-based nano-devices for efficient spin manipulation by means of the g-tensor modulation technique

MEAT PRODUCTIVITY IN BULL FATTENING FOR CORRECTION RACION ON THE EFFECT OF B VITAMINS (В1, В2, В5, В6, В10, В12)

Висвітлюються особливості впливу різних доз комплексу вітамінів групи В (тіамін гідрохлорид, рибофлавін, нікотинова кислота, піридоксин гідрохлорид, фолієва кислота, ціанкобаламін) на забійні показники, хімічний склад і калорійність найдовшого м'яза спини бугайців на відгодівлі.Проведені дослідження показали, що додавання до раціону бугайців на відгодівлі збалансованого за поживними і мінеральними речовинами та жиророзчинними вітамінами А, D, Е комплексу вітамінів групи В (В1, В2, В5, В6, В10, В12) у відповідних дозах в цілому позитивно впливає на м’ясну продуктивність, причому маса охолодженої туші, маса м'якоті, індекс м’ясності, а також хімічний склад, калорійність і білково-якісний показник найдовшого м'яза спини залежить від дози додатково введених до раціону бугайців на відгодівлі вітамінів групи В.Найбільші зміни у забійних показниках, хімічному складі і калорійності м'язової тканини  бугайців на відгодівлі встановлено у тварин  3-ї (В1 – 0,040; В2 – 0,06; В5 – 1,2; В6 – 0,25; В10 – 0,0030; В12 – 0,0006 мг/кг маси тіла) і 4-ї дослідних груп  (В1 – 0,070; В2 – 0,10; В5 – 2,0; В6 – 0,40;  В10 – 0,0050;  В12 – 0,0010 мг/кг маси тіла), а найменші зміни – у бугайців 1-ої дослідної групи (В1 – 0,015;  В2 – 0,03;   В5 – 0,5;В6 – 0,10;  В10 – 0,0012;  В12 - 0,0002 мг/кг маси тіла).Приведены результаты исследований влияния различных доз комплекса витаминов группы В (тиамин гидрохлорид, рибофлавин, никотиновая кислота, пиридоксин гидрохлорид, фоллиевая кислота, цианкобаламин) на убойные показатели, химический состав и калорийность длиннейшей мышцы спины бычков на откорме.Проведенные исследования показали, что добавление в рацион бычков на откорме сбалансированный по питательным, минеральным веществам и жирорастворимым витаминам А, D, Е комплекса витаминов группы В (В1, В2,  В5, В6, В10, В12) в соответствующих дозах в целом положительно влияет на мясную продуктивность, при этом  масса охлажденной туши, масса мякоти, индекс мясности, а также химический состав, калорийность и белково-качественный показатель длиннейшей мышцы спины зависит от дозы дополнительно введенных в рацион бычков на откорме витаминов группы В.Наибольшие изменения в показателях туши бычков, химическому составу и калорийности мышечной ткани бычков на откорме получены у животных 3-й (В1 – 0,040; В2 – 0,06; В5 – 1,2; В6 – 0, 25; В10 – 0,0030; В12 – 0,0006 мг/кг живой массы) и 4-й опытной групп (В1 – 0,070; В2 – 0,10; В5 – 2,0; В6 – 0,40; В10 – 0,0050; В12 – 0,0010 мг/кг живой массы), а наименьшие – у бычков 1-ой опытной группы (В1 –0,015;  В2 – 0,03;   В5 – 0,5; В6 – 0,10;  В10 – 0,0012;  В12 – 0,0002 мг/кг живой массы).Studies have shown that the addition to the diet of calves for fattening complex of B vitamins (В1, В2,  В5, В6, В10, В12) in different doses generally positive effect on  coal indices, chemical composition and caloric longest back muscle bull fattening.Studies have shown that the addition to the diet of bull fattening balanced in nutrients and minerals and fat-soluble vitamins A, D, E complex of B vitamins (В1, В2, В5, В6, В10, В12) in appropriate doses generally positive effect on meat productivity, and chilled carcass weight, weight of pulp meat index and chemical composition, calories and protein-qualitative indicator of the longest back muscle depends on the dose additionally entered the diet fattening bulls B vitaminsThe biggest change on meat productivity, chemical composition, calories of the longest back muscle  of calves for fattening derived from animals 3rd D (B1 – 0,040; B2 – 0,06; B5 – 1,2; B6 – 0 25, B10 – 0,0030; B12 – 0,0006 mg/kg body weight) and 4th D (B1– 0,070; B2 – 0,10; B5 – 2,0; B6 – 0,40; B10 – 0,0050; B12 – 0,0010 mg/kg body weight) groups, and the smallest – in calves 1th D (В1 – 0,015;  В2 – 0,03;   В5 – 0,5; В6 – 0,10;  В10 – 0,0012;  В12 – 0,0002 mg/kg body weight) group

Erythron and protein system in piglets blood under stress influence

The article presents the results of research on the development of adaptive syndrome in the system of erythron and protein of piglets at the effects of weaning stress. After one (anesthetic stage) and seven days (beginning of G.Selle's resistance stage), after the echoing, the adaptation of the erythron system was shown by a decrease in the number of red blood cells on the contrary of increasing the mean corpuscular volume and hemoglobin indicating the inhibition of erythrocytosis with simultaneous macrocytosis, and a decrease in mean Corpuscular hemoglobin concentration for 14.0–13.0 % that indicated hypochromia. In these stressful periods, the catabolism of protein substrates was discovered, the redistribution of albumins between blood and tissues in the form of a decrease in the total protein content by 6.1–7.1 % due to albumin by 14.8–10.0 %, and the deficit of the humoral link of the immune response due to reduction of γ-globulins by 29.9–18.7 %. In the later stages of the resistance stage (after 20 and 60 days after weaning), there was a stabilization of erythrocytic indices and the development of anisocytosis in the form of an increase in red cell distribution width by 19.0 %, with a simultaneous decrease of 6.1 % of the total protein content, redistribution of its fractions in the side of the growth of γ-globulins by 18.4 %. A practical, prolonged way of preventing disorders in the erythron and protein of extramarital piglets was feeding the additive “Biovir”, which stimulated the intensity of oxidative-reducing processes and the exchange of proteins

Bezpieczeństwo i ryzyko podróżowania tanimi liniami lotniczymi

Golovach, E. P.; Rubahov, A. I. Safety and risks of traveling with low-cost airlinesDecydując się na podróż samolotem, jednym z najważniejszych czynników jakie potencjalny turysta bieżę pod uwagę jest kwestia bezpieczeństwa. Szczególnego znaczenia ten czynnik nabiera zwłaszcza w dobie nagłaśnianych i szeroko omawianych katastrof lotniczych w różnych częściach świata oraz bankructwie tanich linii lotniczych w ostatnich latach. W referacie zostali omówione czynniki mające wpływ na bezpieczeństwo i ryzyko podróżowania tanimi liniami lotniczymi. Przedstawione obszary z największą liczbą ofiar wypadków cyvilnych statków powietrznych

The readout of the fullerene-based quantum computing by a scanning tunneling microscope

We consider to detect the electron spin of a doped atom, i.e., a nitrogen or a phosphorus, caged in a fullerene by currently available technique of the scanning tunneling microscope (STM), which actually corresponds to the readout of a qubit in the fullerene-based quantum computing. Under the conditions of polarized STM current and Coulomb blockade, we investigate the tunneling matrix elements involving the exchange coupling between the tunneling polarized electrons and the encapsulated polarized electron, and calculate the variation of the tunneling current with respect to different orientations of the encapsulated electron spin. The experimental feasibility of our scheme is discussed under the consideration of some imperfect factors.Comment: RevTex file, 3 figures. To appear in New Journal of Physic