Optimization in random field Ising models by quantum annealing

We investigate the properties of quantum annealing applied to the random field Ising model in one, two and three dimensions. The decay rate of the residual energy, defined as the energy excess from the ground state, is find to be $e_{res}\sim \log(N_{MC})^{-\zeta}$ with $\zeta$ in the range $2...6$, depending on the strength of the random field. Systems with ``large clusters'' are harder to optimize as measured by $\zeta$. Our numerical results suggest that in the ordered phase $\zeta=2$ whereas in the paramagnetic phase the annealing procedure can be tuned so that $\zeta\to6$.Comment: 7 pages (2 columns), 9 figures, published with minor changes, one reference updated after the publicatio

Elastic lines on splayed columnar defects studied numerically

We investigate by exact optimization method properties of two- and three-dimensional systems of elastic lines in presence of splayed columnar disorder. The ground state of many lines is separable both in 2d and 3d leading to a random walk -like roughening in 2d and ballistic behavior in 3d. Furthermore, we find that in the case of pure splayed columnar disorder in contrast to point disorder there is no entanglement transition in 3d. Entanglement can be triggered by perturbing the pure splay system with point defects.Comment: 9 pages, 11 figures. Accepted for publication in PR

Does nitrate fertilization induce nox emission from scots pine (p. sylvestris) shoots?

Peer reviewe

Convergence theorems for quantum annealing

We prove several theorems to give sufficient conditions for convergence of quantum annealing, which is a protocol to solve generic optimization problems by quantum dynamics. In particular the property of strong ergodicity is proved for the path-integral Monte Carlo implementation of quantum annealing for the transverse Ising model under a power decay of the transverse field. This result is to be compared with the much slower inverse-log decay of temperature in the conventional simulated annealing. Similar results are proved for the Green's function Monte Carlo approach. Optimization problems in continuous space of particle configurations are also discussed.Comment: 19 page

Convergence of Quantum Annealing with Real-Time Schrodinger Dynamics

Convergence conditions for quantum annealing are derived for optimization problems represented by the Ising model of a general form. Quantum fluctuations are introduced as a transverse field and/or transverse ferromagnetic interactions, and the time evolution follows the real-time Schrodinger equation. It is shown that the system stays arbitrarily close to the instantaneous ground state, finally reaching the target optimal state, if the strength of quantum fluctuations decreases sufficiently slowly, in particular inversely proportionally to the power of time in the asymptotic region. This is the same condition as the other implementations of quantum annealing, quantum Monte Carlo and Green's function Monte Carlo simulations, in spite of the essential difference in the type of dynamics. The method of analysis is an application of the adiabatic theorem in conjunction with an estimate of a lower bound of the energy gap based on the recently proposed idea of Somma et. al. for the analysis of classical simulated annealing using a classical-quantum correspondence.Comment: 6 pages, minor correction

Quantum Annealing and Analog Quantum Computation

We review here the recent success in quantum annealing, i.e., optimization of the cost or energy functions of complex systems utilizing quantum fluctuations. The concept is introduced in successive steps through the studies of mapping of such computationally hard problems to the classical spin glass problems. The quantum spin glass problems arise with the introduction of quantum fluctuations, and the annealing behavior of the systems as these fluctuations are reduced slowly to zero. This provides a general framework for realizing analog quantum computation.Comment: 22 pages, 7 figs (color online); new References Added. Reviews of Modern Physics (in press

Metabolic Profiling of Water-Soluble Compounds from the Extracts of Dark Septate Endophytic Fungi (DSE) Isolated from Scots Pine (Pinus sylvestris L.) Seedlings Using UPLC-Orbitrap-MS

Endophytes are microorganisms living inside plant hosts and are known to be beneficial for the host plant vitality. In this study, we isolated three endophytic fungus species from the roots of Scots pine seedlings growing on Finnish drained peatland setting. The isolated fungi belonged to dark septate endophytes (DSE). The metabolic profiles of the hot water extracts of the fungi were investigated using Ultrahigh Performance Liquid Chromatography with Diode Array Detection and Electron Spray Ionization source Mass Spectrometry with Orbitrap analyzer (UPLC-DAD-ESI-MS-Orbitrap). Out of 318 metabolites, we were able to identify 220, of which a majority was amino acids and peptides. Additionally, opine amino acids, amino acid quinones, Amadori compounds, cholines, nucleobases, nucleosides, nucleotides, siderophores, sugars, sugar alcohols and disaccharides were found, as well as other previously reported metabolites from plants or endophytes. Some differences of the metabolic profiles, regarding the amount and identity of the found metabolites, were observed even though the fungi were isolated from the same host. Many of the discovered metabolites have been described possessing biological activities and properties, which may make a favorable contribution to the host plant nutrient availability or abiotic and biotic stress tolerance

Toxicological and bioactivity evaluation of blackcurrant press cake, sea buckthorn leaves and bark from Scots pine and Norway spruce extracts under a green integrated approach

Aqueous extracts from blackcurrant press cake (BC), Norway spruce bark (NS), Scots pine bark (SP), and sea buckthorn leaves (SB) were obtained using maceration and pressurized hot water and tested for their bioactivities. Maceration provided the extraction of higher dry matter contents, including total phenolics (TPC), anthocyanins, and condensed tannins, which also impacted higher antioxidant activity. NS and SB extracts presented the highest mean values of TPC and antioxidant activity. Individually, NS extract presented high contents of proanthocyanidins, resveratrol, and some phenolic acids. In contrast, SB contained a high concentration of ellagitannins, ellagic acid, and quercetin, explaining the antioxidant activity and antibacterial effects. SP and BC extracts had the lowest TPC and antioxidant activity. However, BC had strong antiviral efficacy, whereas SP can be considered a potential ingredient to inhibit α-amylase. Except for BC, the other extracts decreased reactive oxygen species (ROS) generation in HCT8 and A549 cells. Extracts did not inhibit the production of TNF-alpha in lipopolysaccharide-stimulated THP-1 macrophages but inhibited the ROS generation during the THP-1 cell respiratory burst. The recovery of antioxidant compounds from these by-products is incentivized for high value-added applications.</p

Impact of selenium enrichment on seed potato tubers

The aim of this study was to investigate the effect of Se enrichment on the growth of sprouts and growth vigour of seed potatoes (Solanum tuberosum L.) stored for 2 to 8 months. Our results showed that Se did not affect the duration of dormancy. At the high addition levels (0.075 and 0.9 mg kg-1 quartz sand), Se had some positive effects on the growth of sprouts. The peak sprouting capacity was reached after 8 months of storage. The highest Se enrichment of tubers had some positive effect on the free putrescine content in sprouts. However, the better growth of sprouts was not consistent with the growth vigour of the seed tubers and yield produced. Selenium had no significant effect on the malondialdehyde (MDA) or on the concentration of soluble sugars and starch. No significant effect of added Se on the early growth, stem and tuber numbers and yield parameters was observed. Irrespective of the level of Se added, the highest yield was harvested from plants produced with seed tubers stored for 6 months. Our results indicate that Se had some positive effects on the growth of sprouts, but it had no consistent effect on the growth vigour of seed tubers.;Suomessa perunaa joudutaan varastoimaan pitkaan. Varastoinninaikana siemenperunassa tapahtuu fysiologisia ja biokemiallisia muutoksia, jotka johtavat hiljalleen fysiologiseen vanhenemiseen ja sita kautta mukulan elinvoiman ja sadonmuodostuskyvyn alenemiseen. Seleeni (Se) on valttamaton alkuaine ihmisten ja elainten terveydelle. Viljelykasvien ei ole katsottu valttamatta tarvitsevan seleenia. Kuitenkin pienen seleenilisayksen on havaittu lisaavan kasvien antioksidatiivista kapasiteettia, parantavan kasvien kasvua, satoa ja laatua seka hidastavan kasvien vanhenemista. Helsingin yliopistossa Soveltavan biologian laitoksella tutkittiin voiko seleeni edistaa siemenperunan elinvoiman sailymista seka hidastaa vanhenemista varastoinnin aikana. Seleenirikastetut siemenperunat tuotettiin edellisena kasvukautena kasvihuoneessa kasveissa, jotka kasvatettiin nousevilla seleenimaarilla (0, 0.0035, 0.01, 0.075 ja 0.9 mg Se kg-1) lannoitetussa kvartsihiekassa, joilla siemenperunoiden seleenipitoisuudet olivat keskimaarin 0.01, 0.09, 0.20, 1.33 and 16 Êg Se g-1 kuivapainoa, tassa jarjestyksessa. Seleenin vaikutusta siemenperunan itujen kasvuun tutkittiin maarittamalla itujen lukumaara ja itamiskapasiteetti. Iduista maaritettiin vapaiden polyamiinien pitoisuus. Malondialdehydin (MDA) ja liukoisten sokereiden kertyminen sekä tärkkelyksen hajoaminen määritettiin siemenperunoista varastoinnin aikana. Siemenperunoiden elinvoima tutkittiin kasvihuonekokeissa määrittämällä taimettumisaika, kukinnan alkamisaika, pääversojen lukumäärä sekä kasvikohtaisesti sato, mukulalukumäärä ja mukulapaino. Tutkimuksen tulokset osoittivat, että korkeimmat seleenilisäykset (0.075 ja 0.9 mg kg-1) paransivat itämiskapasiteettia eli suurempi osa olemassa olevista iduista oli lähtenyt kasvuun. Korkeimmalla seleenirikastuksella oli positiivinen vaikutus itujen vapaan putreskiinin pitoisuuteen. Lisääntynyt itujen kasvu ei ollut yhteydessä siemenperunoiden elinvoimaan eli tuotetun sadon määrään. Seleenirikastuksella ei ollut vaikutusta perunoiden MDA:n eikä liukoisten sokereiden kertymiseen eikä tärkkelyksen hajoamiseen. Korkein sato tuotettiin kuusi kuukautta varastoidulla siemenperunalla, riippumatta seleenilisäyksestä. Kahdeksan kuukautta varastoidut siemenperunat sen sijaan tuottivat alhaisemman sadon, mikä viittaa siihen, että siemenperunan optimaalinen ikä oli jo ohitettu. Tulokset osoittavat, että seleenirikastuksella ei ollut selvää siemenperunoiden vanhenemista hidastavaa eikä niiden elinvoimaa edistävää vaikutusta