The planar spectrum in U(N)-invariant quantum mechanics by Fock space methods: I. The bosonic case

Prompted by recent results on Susy-U(N)-invariant quantum mechanics in the large N limit by Veneziano and Wosiek, we have examined the planar spectrum in the full Hilbert space of U(N)-invariant states built on the Fock vacuum by applying any U(N)-invariant combinations of creation-operators. We present results about 1) the supersymmetric model in the bosonic sector, 2) the standard quartic Hamiltonian. This latter is useful to check our techniques against the exact result of Brezin et al. The SuSy case is where Fock space methods prove to be the most efficient: it turns out that the problem is separable and the exact planar spectrum can be expressed in terms of the single-trace spectrum. In the case of the anharmonic oscillator, on the other hand, the Fock space analysis is quite cumbersome due to the presence of large off-diagonal O(N) terms coupling subspaces with different number of traces; these terms should be absorbed before taking the planar limit and recovering the known planar spectrum. We give analytical and numerical evidence that good qualitative information on the spectrum can be obtained this way.Comment: 17 pages, 4 figures, uses youngtab.sty. Final versio

On the definition of Quantum Free Particle on Curved Manifolds

A selfconsistent definition of quantum free particle on a generic curved manifold emerges naturally by restricting the dynamics to submanifolds of co-dimension one. PACS 0365 0240Comment: 8 p., phyzzx macropackag

Effects of sub-optimal temperatures on seed germination of three warm-season turfgrasses with perspectives of cultivation in transition zone

Warm-season turfgrass species prevail in tropical and subtropical areas, but can also be grown in the transition zone. In this case, cold tolerance is a key aspect for germination and successful turfgrass establishment. The germination response to sub-optimal temperatures was investigated for Cynodon dactylon (cvs Jackpot, La Paloma, Transcontinental, Yukon, Riviera), Buchloe dactyloides (cv SWI 2000) and Paspalum vaginatum (cv Pure Dynasty). Four temperature regimes were applied, i.e., 20/30 °C, 15/25 °C, 10/20 °C and 5/15 °C, with a 12:12 h (light:dark) photoperiod. Germination assays were performed twice, with six replicates (Petri dishes) per treatment in each experiment, fifty seeds per dish. The final germinated percentages at last inspection time (FGP) were obtained for each Petri dish and processed by using a generalized linear mixed model (binomial error and logit link). Germination curves were fitted to each Petri dish by using time-to-event methods and germination rates (GR) for the 10th, 20th and 30th percentiles were derived and used to fit a linear thermal-time model. For all cultivars, FGP decreased with decreasing mean daily temperatures. Base temperatures (Tb) ranged between 11.4 °C and 17.0 °C, while the thermal time to obtain 30% germination ranged from 51.3 °C day for SWI 2000 to 144.0 °C day for Pure Dynasty. The estimated parameters were used to predict germination time in the field, considering the observed soil temperatures in Legnaro. The estimated date for the beginning of germination in the field would range from early April for SWI 2000 and Transcontinental to mid-May for Riviera. These results might be used as a practical support for planning spring sowing, which is crucial for successful turfgrass establishment, especially without irrigation

BIOMEX (Biology and Mars Experiment): Preliminary results on Antarctic black cryptoendolithic fungi in ground based experiments

The main goal for astrobiologists is to find traces of present or past life in extraterrestrial environment or in meteorites. Biomolecules, such as lipids, pigments or polysaccharides, may be useful to establish the presence of extant or extinct life (Simoneit, B et al., 1998). BIOMEX (Biology and Mars Experiment) aims to measure to what extent biomolecules, such as pigments and cellular components, preserve their stability under space and Mars-like conditions. The experiment has just been launched in the space and will be exposed on EXPOSE-R payload to the outside of the International Space Station (ISS) for about 2 years. Among a number of extremophilic microorganisms tested, the Antarctic cryptoendolithic black fungus Cryomyces antarcticus CCFEE 515 was included in the experiment. The fungus, living in the airspaces of porous rocks, was already chosen in previous astrobiological investigation for studying the interplanetary transfer of life via meteorites. In that context, the fungus survived 18 months of exposure outside of the ISS (Onofri al., 2012); for all these reasons it is considered an optimal eukaryotic model for astrobiological exploration. Before launch dried samples were exposed, in ground based experiments, to extreme conditions, including vacuum, irradiation and temperature cycles.Upon sample re-hydration and survival analysis, including colony forming ability, Propidium MonoAzide (PMA) assay-coupled quantitative PCR (Mohapatra and La Duc, 2012) all the test systems survived, neither any DNA damage was detectable. Our analyses focused also on mineral-microorganisms interactions and stability/degradation of typical fungal macromolecules, in particular melanin, when exposed to space and simulated Martian conditions, contributing to the development of libraries of biosignatures in rocks, supporting future exploration missions

Spectral Analysis of Ultrasonic and Photo Acoustic Signals Generated by a Prototypal Fiber Microprobe for Media Characterization

AbstractCombination of photoacoustics and ultrasound can provide complemental features and mutual benefits, useful for a complete tissue characterization and consequently for early diagnosis or therapy monitoring. Furthermore, minimally invasive techniques are required both to reach organs or tissue not accessible and to reduce patient discomfort and costs. This work has tested a prototypal microprobe for media characterization analysing their optical and mechanical features. Two different transmitters compose the miniaturized probe: one for large bandwidth ultrasonic signals generation and one for guiding the laser light into tissue to photogenerate ultrasound. The aim is to evaluate the possibility of employing in the future this new type of microprobe to characterize internal tissue, combining ultrasound and photoacoustic investigations. A calibrated commercial hydrophone has been used to detect generated signals, with the aim to provide repeatable and reliable results. Dedicated test objects have been realized by using solutions of corn starch flour and of Chinese ink with different and calibrated dilutions. The spectral algorithm HyperSPACE (Hyper SPectral Analysis for Characterization in Echography), applied on ultrasonic and photoacoustic signals has allowed differentiating scatterers' concentration and distribution

Resistance of Antarctic black fungi and cryptoendolithic communities to simulated space and Martian conditions

Dried colonies of the Antarctic rock-inhabiting meristematic fungi Cryomyces antarcticus CCFEE 515, CCFEE 534 and C. minteri CCFEE 5187, as well as fragments of rocks colonized by the Antarctic cryptoendolithic community, were exposed to a set of ground-based experiment verification tests (EVTs) at the German Aerospace Center (DLR, Köln, Germany). These were carried out to test the tolerance of these organisms in view of their possible exposure to space conditions outside of the International Space Station (ISS). Tests included single or combined simulated space and Martian conditions. Responses were analysed both by cultural and microscopic methods. Thereby, colony formation capacities were measured and the cellular viability was assessed using live/dead dyes FUN 1 and SYTOX Green. The results clearly suggest a general good resistance of all the samples investigated. C. minteri CCFEE 5187, C. antarcticus CCFEE 515 and colonized rocks were selected as suitable candidates to withstand space flight and long-term permanence in space on the ISS in the framework of the LIchens and Fungi Experiments (LIFE programme, European Space Agency)

Boundary One-Point Functions, Scattering, and Background Vacuum Solutions in Toda Theories

The parametric families of integrable boundary affine Toda theories are considered. We calculate boundary one-point functions and propose boundary S-matrices in these theories. We use boundary one-point functions and S-matrix amplitudes to derive boundary ground state energies and exact solutions describing classical vacuum configurations.Comment: 20 pages, LaTe

A negative mass theorem for surfaces of positive genus

We define the "sum of squares of the wavelengths" of a Riemannian surface (M,g) to be the regularized trace of the inverse of the Laplacian. We normalize by scaling and adding a constant, to obtain a "mass", which is scale invariant and vanishes at the round sphere. This is an anlaog for closed surfaces of the ADM mass from general relativity. We show that if M has positive genus then on each conformal class, the mass attains a negative minimum. For the minimizing metric, there is a sharp logarithmic Hardy-Littlewood-Sobolev inequality and a Moser-Trudinger-Onofri type inequality.Comment: 8 page

Exact and semiclassical approach to a class of singular integral operators arising in fluid mechanics and quantum field theory

A class of singular integral operators, encompassing two physically relevant cases arising in perturbative QCD and in classical fluid dynamics, is presented and analyzed. It is shown that three special values of the parameters allow for an exact eigenfunction expansion; these can be associated to Riemannian symmetric spaces of rank one with positive, negative or vanishing curvature. For all other cases an accurate semiclassical approximation is derived, based on the identification of the operators with a peculiar Schroedinger-like operator.Comment: 12 pages, 1 figure, amslatex, bibtex (added missing label eq.11

Metagenomes in the borderline ecosystems of the Antarctic cryptoendolithic communities

Antarctic cryptoendolithic communities are microbial ecosystems dwelling inside rocks of the Antarctic desert. We present the first 18 shotgun metagenomes from these communities to further characterize their composition, biodiversity, functionality, and adaptation. Future studies will integrate taxonomic and functional annotations to examine the pathways necessary for life to evolve in the extreme