Subfactor realisation of modular invariants

We study the problem of realising modular invariants by braided subfactors and the related problem of classifying nimreps. We develop the fusion rule structure of these modular invariants. This structure is useful tool in the analysis of modular data from quantum double subfactors, particularly those of the double of cyclic groups, the symmetric group on 3 letters and the double of the subfactors with principal graph the extended Dynkin diagram D_5^(1). In particular for the double of S_3, 14 of the 48 modular modular invariants are nimless, and only 28 of the remaining 34 nimble invariants can be realised by subfactors

Type II Supernovae as Standardized Candles

We present evidence for a correlation between expansion velocities of the ejecta of Type II plateau supernovae and their bolometric luminosities during the plateau phase. This correlation permits one to standardize the candles and decrease the scatter in the Hubble diagram from ~1 mag to a level of 0.4 and 0.3 mag in the V and I bands, respectively. When we restrict the sample to the eight objects which are well in the Hubble flow (cz > 3,000 km/s) the scatter drops even further to only 0.2 mag (or 9% in distance), which is comparable to the precision yielded by Type Ia supernovae and far better than the ``expanding photosphere method'' applied to Type II supernovae. Using SN 1987A to calibrate the Hubble diagrams we get Ho=55+/-12.Comment: 9 pages, 3 figures, 1 table, accepted by ApJ

Selection Effects, Biases, and Constraints in the Calan/Tololo Supernova Survey

We use Monte Carlo simulations of the Calan/Tololo photographic supernova survey to show that a simple model of the survey's selection effects accounts for the observed distributions of recession velocity, apparent magnitude, angular offset, and projected radial distance between the supernova and the host galaxy nucleus for this sample of Type Ia supernovae (SNe Ia). The model includes biases due to the flux-limited nature of the survey, the different light curve morphologies displayed by different SNe Ia, and the difficulty of finding events projected near the central regions of the host galaxies. From these simulations we estimate the bias in the zero-point and slope of the absolute magnitude-decline rate relation used in SNe Ia distance measurements. For an assumed intrinsic scatter of 0.15 mag about this relation, these selection effects decrease the zero-point by 0.04 mag. The slope of the relation is not significantly biased. We conclude that despite selection effects in the survey, the shape and zero-point of the relation determined from the Calan/Tololo sample are quite reliable. We estimate the degree of incompleteness of the survey as a function of decline rate and estimate a corrected luminosity function for SNe Ia in which the frequency of SNe appears to increase with decline rate (the fainter SNe are more common). Finally, we compute the integrated detection efficiency of the survey in order to infer the rate of SNe Ia from the 31 events found. For a value of Ho=65 km/sec/Mpc we obtain a SN Ia rate of 0.21(+0.30)(-0.13) SNu. This is in good agreement with the value 0.16+/-0.05 SNu recently determined by Capellaro et al. (1997).Comment: 36 pages, 19 figures as extra files, to appear in the A

Ketogenic diet-induced weight loss is associated with an increase in vitamin d levels in obese adults

Vitamin D is an important micronutrient involved in several processes. Evidence has shown a strong association between hypovitaminosis D and cardio-metabolic diseases, including obesity. A ketogenic diet has proven to be very effective for weight loss, especially in reducing fat mass while preserving fat-free mass. The aim of this study was to investigate the effect of a ketogenic diet-induced weight loss on vitamin D status in a population of obese adults. We enrolled 56 obese outpatients, prescribed with either traditional standard hypocaloric Mediterranean diet (SHMD) or very low-calorie ketogenic diet (VLCKD). Serum 25(OH)D concentrations were measured by chemiluminescence. The mean value of serum 25-hydroxyvitamin D (25(OH)D) concentrations in the whole population at baseline was 17.8 +/- 5.6 ng/mL, without differences between groups. After 12 months of dietetic treatment, in VLCKD patients serum 25(OH)D concentrations increased from 18.4 +/- 5.9 to 29.3 +/- 6.8 ng/mL (p < 0.0001), vs 17.5 +/- 6.1 to 21.3 +/- 7.6 ng/mL (p = 0.067) in the SHMD group (for each kilogram of weight loss, 25(OH)D concentration increased 0.39 and 0.13 ng/mL in the VLCKD and in the SHMD groups, respectively). In the VLCKD group, the increase in serum 25(OH)D concentrations was strongly associated with body mass index, waist circumference, and fatty mass variation. In a multiple regression analysis, fatty mass was the strongest independent predictor of serum 25(OH)D concentration, explaining 15.6%, 3.3%, and 9.4% of its variation in the whole population, in SHMD, and VLCKD groups, respectively. We also observed a greater reduction of inflammation (evaluated by high-sensitivity C reactive protein (hsCRP) values) and a greater improvement in glucose homeostasis, confirmed by a reduction of HOMA values, in the VLCKD versus the SHMD group. Taken together, all these data suggest that a dietetic regimen, which implies a great reduction of fat mass, can improve vitamin D status in the obese

The distance to the LMC cluster NGC 1866 and the surrounding field

We use the Main Sequence stars in the LMC cluster NGC 1866 and of Red Clump stars in the local field to obtain two independent estimates of the LMC distance. We apply an empirical Main Sequence-fitting technique based on a large sample of subdwarfs with accurate {\sl Hipparcos} parallaxes in order to estimate the cluster distance modulus, and the multicolor Red Clump method to derive distance and reddening of the LMC field. We find that the Main Sequence-fitting and the Red Clump distance moduli are in significant disagreement; NGC 1866 distance is equal to $\rm (m-M)_{0,NGC 1866}=18.33\pm$0.08 (consistent with a previous estimate using the same data and theoretical Main Sequence isochrones), while the field stars provide $\rm (m-M)_{0,field}=18.53\pm$0.07. This difference reflects the more general dichotomy in the LMC distance estimates found in the literature. Various possible causes for this disagreement are explored, with particular attention paid to the still uncertain metallicity of the cluster and the star formation history of the field stars.Comment: 5 pages, incl. 1 figure, uses emulateapj.sty, ApJ accepte

The ages of very cool hydrogen-rich white dwarfs

The evolution of white dwarfs is essentially a cooling process that depends primarily on the energy stored in their degenerate cores and on the transparency of their envelopes. In this paper we compute accurate cooling sequences for carbon-oxygen white dwarfs with hydrogen dominated atmospheres for the full range of masses of interest. For this purpose we use the most accurate available physical inputs for both the equation of state and opacities of the envelope and for the thermodynamic quantities of the degenerate core. We also investigate the role of the latent heat in the computed cooling sequences. We present separately cooling sequences in which the effects of phase separation of the carbon-oxygen binary mixture upon crystallization have been neglected, and the delay introduced in the cooling times when this mechanism is properly taken into account, in order to compare our results with other published cooling sequences which do not include a treatment of this phenomenon. We find that the cooling ages of very cool white dwarfs with pure hydrogen atmospheres have been systematically underestimated by roughly 1.5 Gyr at log(L/Lo)=-4.5 for an otherwise typical 0.6 Mo white dwarf, when phase separation is neglected. If phase separation of the binary mixture is included then the cooling ages are further increased by roughly 10%. Cooling tracks and cooling isochrones in several color-magnitude diagrams are presented as well.Comment: 8 Pages; ApJ, accepted for publicatio

Nonclassical correlation in NMR quadrupolar systems

The existence of quantum correlation (as revealed by quantum discord), other than entanglement and its role in quantum-information processing (QIP), is a current subject for discussion. In particular, it has been suggested that this nonclassical correlation may provide computational speedup for some quantum algorithms. In this regard, bulk nuclear magnetic resonance (NMR) has been successfully used as a test bench for many QIP implementations, although it has also been continuously criticized for not presenting entanglement in most of the systems used so far. In this paper, we report a theoretical and experimental study on the dynamics of quantum and classical correlations in an NMR quadrupolar system. We present a method for computing the correlations from experimental NMR deviation-density matrices and show that, given the action of the nuclear-spin environment, the relaxation produces a monotonic time decay in the correlations. Although the experimental realizations were performed in a specific quadrupolar system, the main results presented here can be applied to whichever system uses a deviation-density matrix formalism.Comment: Published versio

Seismic Reliability Analysis of Structures

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