Charge Gap in the One-Dimensional Extended Hubbard Model at Quarter Filling

We propose a new combined approach of the exact diagonalization, the renormalization group and the Bethe ansatz for precise estimates of the charge gap $\Delta$ in the one-dimensional extended Hubbard model with the onsite and the nearest-neighbor interactions $U$ and $V$ at quarter filling. This approach enables us to obtain the absolute value of $\Delta$ including the prefactor without ambiguity even in the critical regime of the metal-insulator transition (MIT) where $\Delta$ is exponentially small, beyond usual renormalization group methods and/or finite size scaling approaches. The detailed results of $\Delta$ down to of order of $10^{-10}$ near the MIT are shown as contour lines on the $U$-$V$ plane.Comment: 4 pages, 4 figure

The three-dimensional BF Model with Cosmological Term in the Axial Gauge

We quantize the three-dimensional $BF$-model using axial gauge conditions. Exploiting the rich symmetry-structure of the model we show that the Green-functions correspond to tree graphs and can be obtained as the unique solution of the Ward-Identities. Furthermore, we will show that the theory can be uniquely determined by symmetry considerations without the need of an action principle.Comment: one reference added, transmission errors correcte

Combined Analysis of Numerical Diagonalization and Renormalization Group methods for the One-Dimensional UU-VV Model at Quarter filling

The one-dimensional extended Hubbard model with both the on-site $U$ and the nearest neighbor $V$ interactions at quarter filling is studied by using a novel finite size scaling. We diagonalize finite size systems numerically and calculate the Luttinger-liquid parameter $K_{\rho}$ which is substituted into the renormalization group equation as an initial condition. It leads $K_\rho$ in the infinite size system and the result agrees very well with the available exact result with $U=\infty$. This approach also yields the charge gap in the insulating state near the metal-insulator transition where the characteristic energy becomes exponentially small and the usual finite size scaling is not applicable.Comment: 7 pages, 8 figures,submitted to PR

Detection of Water and/or Hydroxyl on Asteroid (16) Psyche

In order to search for evidence of hydration on M-type asteroid (16) Psyche, we observed this object in the 3 micron spectral region using the long-wavelength cross-dispersed (LXD: 1.9-4.2 micron) mode of the SpeX spectrograph/imager at the NASA Infrared Telescope Facility (IRTF). Our observations show that Psyche exhibits a 3 micron absorption feature, attributed to water or hydroxyl. The 3 micron absorption feature is consistent with the hydration features found on the surfaces of water-rich asteroids, attributed to OH- and/or H2O-bearing phases (phyllosilicates). The detection of a 3 micron hydration absorption band on Psyche suggests that this asteroid may not be metallic core, or it could be a metallic core that has been impacted by carbonaceous material over the past 4.5 Gyr. Our results also indicate rotational spectral variations, which we suggest reflect heterogeneity in the metal/silicate ratio on the surface of Psyche.Comment: 13 pages, 9 figures in Astronomical Journal, 201

Source of water in basins off southern California

Water temperature and salinity measurements from most of the 14 basins off southern California, when compared with older data, show no detectable changes. The water in each basin is nearly isothermal and isohaline from the bottom to near the sill depth...

Wave patterns off southern California

Mapping of wave trains during four flights over the ocean off southern California showed the consistent presence of a high 10-second swell from the westnorthwest, of one or two low 3- to 5-second swells from other westerly directions, and of local wind waves; occasionally a low 13-second swell from the west and southwest was also present. Islands reduce the height of swells but produce little discernable crossswell in their lee...

The Influence of Diet and Oxidation on Calcium Retention of the Mitochondria in Fresh Beef

Distillers grains (DG) contribute to cattle sarcoplasmic reticulum (SR) membrane instability by increasing poly-unsaturated fatty acid (PUFA) content in the SR membrane, possibly resulting in early postmortem calcium (Ca) leakage and improved tenderness. Mitochondria are relatively easy to isolate intact and provide the opportunity to study Ca in an SR model. The objective of this research was to determine the influence of diet and oxidation on Ca release from mitochondria. Cattle (n=48) were fed a corn-based finishing diet with or without deoiled, dried DG (50% DM basis). Steaks from each strip loin were aged for 2, 8, 14, and 21 days, powdered, and stored at -80oC for lab analysis. Samples (n=12) were randomly sub-sampled from each diet group for all aging periods. Mitochondria were isolated from day 2, 8, and 14 day-aged samples using high speed ultracentrifugation. The SR was isolated from each day 2 sample. Both mitochondria and SR samples were analyzed for PUFA content using gas chromatography, and phospholipid content using thin layer chromatography. Mitochondria from days 2 and 8 were artificially oxidized using an iron and ascorbic acid mixture. In both organelles, the DG diet samples had higher 18:2 and total PUFA content (P\u3c0.05) contents compared to day 2 and 8 mitochondria, as expected from aging of unsaturated fats. Phospholipid contents (phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol) of the mitochondria and SR were unaffected by diet. Oxidized mitochondria retained significantly less Ca than non-oxidized (P\u3c0.05) mitochondria. Day 2 mitochondria retained significantly less Ca than day 8 (P\u3c0.05) mitochondria. Overall, mitochondria from cattle finished on corn tended (P\u3c0.10) to retain more Ca than mitochondria from cattle finished on DG. Results indicate that greater PUFA content deposited in organelles by the DG diet may affect Ca flux by increased susceptibility to oxidation. A DG diet may influence Ca flux and ultimate tenderness by this mechanism. Advisor: Chris R. Calkin

Oceanography on a Postage Stamp

Many postage stamps have designs that illustrate various aspects of oceanography. A representative selection of them reveals an international interest in the oceans