Solitonic State in Microscopic Dynamic Failures

Onset of permanent deformation in crystalline materials under a sharp indenter tip is accompanied by nucleation and propagation of defects. By measuring the spatio-temporal strain field nearthe indenter tip during indentation tests, we demonstrate that the dynamic strain history at the moment of a displacement burst carries characteristics of formation and interaction of local excitations, or solitons. We show that dynamic propagation of multiple solitons is followed by a short time interval where the propagating fronts can accelerate suddenly. As a result of such abrupt local accelerations, duration of the fast-slip phase of a failure event is shortened. Our results show that formation and annihilation of solitons mediate the microscopic fast weakening phase, during which extreme acceleration and collision of solitons lead to non-Newtonian behavior and Lorentz contraction, i.e., shortening of solitons characteristic length. The results open new horizons for understanding dynamic material response during failure and, more generally, complexity of earthquake sources

Interaction of plant amine oxidases with diaminoethers

Polyamines are ubiquitous compounds, which are involved in crucial physiological events including cell growth and differentiation. The catabolic oxidative degradation of polyamines is catalyzed by quinoprotein copper-containing amine oxidases (CAOs) and flavoprotein polyamine oxidases (PAOs). Various synthetic polyamine analogs and polyamine derivatives have been reported, which represent important tools (substrates or inhibitors) in the study of catalytic properties of the enzymes. In this work, two related compounds were studied in the reactions with plant amine oxidases: 1,8-diamino-3,6-dioxaoctane (DADO) and 1,10-bis(2- pyridinylmethyl)-4,7-dioxa-1,10-diazadecane (BPDD). Based on activity and stoichiometry assays together with spectrophotometric measurements, DADO can be considered a good substrate for grass pea, lentil and E. characias CAOs with Km values in the range 10-4 – 10-3 M. Its oxidative degradation produces the corresponding aminoaldehyde 8-amino-3,6-dioxaoctanal, which does not undergo spontaneous cyclization (as it is known for the oxidation products of natural substrates putrescine, cadaverine and spermidine) or polymerization in the reaction mixture. Conversely, oat PAO does not oxidize DADO and is only weakly inhibited by the compound (Ki = 1.6 mM towards putrescine). BPDD was found to be a competitive inhibitor of both CAOs and PAOs with Ki values of 10-4 M. DADO could be suggested as a potential affinity ligand for CAOs

Further mismeasures of animal contests: a new framework for assessment strategies

Abstract Competition for resources is a ubiquitous feature of life, and a central topic in behavioral ecology. Organisms use assessment strategies to resolve contests, which can be delineated into two broad categories by the information individuals use to make decisions: mutual assessment (MA) or self-assessment (SA). Most research hitherto has worked to bin a species into one of these categories. In this review, we discuss the limitations of this approach and provide solutions. We posit that assessment strategies do not need to be fixed within a species, individuals, or interactions, and that many organisms should adjust their assessment strategy as the environment, opponent, and opportunities for information gathering change. We show that assessment strategies are an individual-level characteristic, can vary within and between contests, and are not mutually exclusive. We argue that MA is the midpoint along a spectrum of self only and opponent only assessment. We discuss the effects of resource distribution, demographics, experience, information transfer, and ontogeny on assessment strategy evolution and behavior. We conclude by providing empirical guidelines and an example with a simulated dataset.</jats:p

A side-by-side comparison of Daya Bay antineutrino detectors

The Daya Bay Reactor Neutrino Experiment is designed to determine precisely the neutrino mixing angle θ_(13) with a sensitivity better than 0.01 in the parameter sin^22θ_(13) at the 90% confidence level. To achieve this goal, the collaboration will build eight functionally identical antineutrino detectors. The first two detectors have been constructed, installed and commissioned in Experimental Hall 1, with steady data-taking beginning September 23, 2011. A comparison of the data collected over the subsequent three months indicates that the detectors are functionally identical, and that detector-related systematic uncertainties are smaller than requirements

Fungal Community Response to Long-Term Soil Warming With Potential Implications for Soil Carbon Dynamics

The direction and magnitude of climate warming effects on ecosystem processes such as carbon cycling remain uncertain. Soil fungi are central to these processes due to their roles as decomposers of soil organic matter, as mycorrhizal symbionts, and as determinants of plant diversity. Yet despite their importance to ecosystem functioning, we lack a clear understanding of the long-term response of soil fungal communities to warming. Toward this goal, we characterized soil fungal communities in two replicated soil warming experiments at the Harvard Forest (Petersham, Massachusetts, USA) which had experienced 5 degrees C above ambient soil temperatures for 5 and 20 yr at the time of sampling. We assessed fungal diversity and community composition by sequencing the ITS2 region of rDNA using Illumina technology, along with soil C concentrations and chemistry. Three main findings emerged: (1) long-, but not short-term warming resulted in compositional shifts in the soil fungal community, particularly in the saprotrophic and unknown components of the community; (2) soil C concentrations and the total C stored in the organic horizon declined in response to both short- (5 yr) and long-term (20 yr) warming; and (3) following long-term warming, shifts in fungal guild relative abundances were associated with substantial changes in soil organic matter chemistry, particularly the relative abundance of lignin. Taken together, our results suggest that shifts with warming in the relative abundance of fungal functional groups and dominant fungal taxa are related to observed losses in total soil C

New measurement of θ13\theta_{13} via neutron capture on hydrogen at Daya Bay

This article reports an improved independent measurement of neutrino mixing angle $\theta_{13}$ at the Daya Bay Reactor Neutrino Experiment. Electron antineutrinos were identified by inverse $\beta$-decays with the emitted neutron captured by hydrogen, yielding a data-set with principally distinct uncertainties from that with neutrons captured by gadolinium. With the final two of eight antineutrino detectors installed, this study used 621 days of data including the previously reported 217-day data set with six detectors. The dominant statistical uncertainty was reduced by 49%. Intensive studies of the cosmogenic muon-induced $^9$Li and fast neutron backgrounds and the neutron-capture energy selection efficiency, resulted in a reduction of the systematic uncertainty by 26%. The deficit in the detected number of antineutrinos at the far detectors relative to the expected number based on the near detectors yielded $\sin^22\theta_{13} = 0.071 \pm 0.011$ in the three-neutrino-oscillation framework. The combination of this result with the gadolinium-capture result is also reported.Comment: 26 pages, 23 figure

A new measurement of antineutrino oscillation with the full detector configuration at Daya Bay

We report a new measurement of electron antineutrino disappearance using the fully-constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9$\times$10$^5$ GW$_{\rm th}$-ton-days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six $^{241}$Am-$^{13}$C radioactive calibration sources reduced the background by a factor of two for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of $\sin^{2}2\theta_{13}$ and $|\Delta m^2_{ee}|$ were halved as a result of these improvements. Analysis of the relative antineutrino rates and energy spectra between detectors gave $\sin^{2}2\theta_{13} = 0.084\pm0.005$ and $|\Delta m^{2}_{ee}|= (2.42\pm0.11) \times 10^{-3}$ eV$^2$ in the three-neutrino framework.Comment: Updated to match final published versio

Evolution of the Reactor Antineutrino Flux and Spectrum at Daya Bay

The Daya Bay experiment has observed correlations between reactor core fuel evolution and changes in the reactor antineutrino flux and energy spectrum. Four antineutrino detectors in two experimental halls were used to identify 2.2 million inverse beta decays (IBDs) over 1230 days spanning multiple fuel cycles for each of six 2.9 GW$_{\textrm{th}}$ reactor cores at the Daya Bay and Ling Ao nuclear power plants. Using detector data spanning effective $^{239}$Pu fission fractions, $F_{239}$, from 0.25 to 0.35, Daya Bay measures an average IBD yield, $\bar{\sigma}_f$, of $(5.90 \pm 0.13) \times 10^{-43}$ cm$^2$/fission and a fuel-dependent variation in the IBD yield, $d\sigma_f/dF_{239}$, of $(-1.86 \pm 0.18) \times 10^{-43}$ cm$^2$/fission. This observation rejects the hypothesis of a constant antineutrino flux as a function of the $^{239}$Pu fission fraction at 10 standard deviations. The variation in IBD yield was found to be energy-dependent, rejecting the hypothesis of a constant antineutrino energy spectrum at 5.1 standard deviations. While measurements of the evolution in the IBD spectrum show general agreement with predictions from recent reactor models, the measured evolution in total IBD yield disagrees with recent predictions at 3.1$\sigma$. This discrepancy indicates that an overall deficit in measured flux with respect to predictions does not result from equal fractional deficits from the primary fission isotopes $^{235}$U, $^{239}$Pu, $^{238}$U, and $^{241}$Pu. Based on measured IBD yield variations, yields of $(6.17 \pm 0.17)$ and $(4.27 \pm 0.26) \times 10^{-43}$ cm$^2$/fission have been determined for the two dominant fission parent isotopes $^{235}$U and $^{239}$Pu. A 7.8% discrepancy between the observed and predicted $^{235}$U yield suggests that this isotope may be the primary contributor to the reactor antineutrino anomaly.Comment: 7 pages, 5 figure