Do retail coffee prices increase faster than they fall? Asymmetric price transmission in France, Germany and the United States

This investigation examines price transmission asymmetries (PTA) between international and retail coffee prices in the US, France and Germany. Differences in price transmission mechanisms provide evidence for disparities in market structure and market performance across countries. Although all processors of roasted coffee purchase green coffee at the same price in the international markets, one finds significant differences in retail prices among these countries. The study develops an Error Correction (EC) representation model to assess PTA of non-stationary models. Finally, it claims that identifying differences in price transmission asymmetry is an approach to compare market structure across countries.coffee, markets, Food Consumption/Nutrition/Food Safety, Marketing,

Imaging the Small-Scale Circumstellar Gas Around T~Tauri Stars

We have detected circumstellar molecular gas around a small sample of T Tauri stars through aperture synthesis imaging of CO(2-1) emission at ~2-3'' resolution. RY Tauri, DL Tauri, DO Tauri, and AS 209 show resolved and elongated gaseous emission. For RY Tau, the deconvolved, half-maximum radius along the direction of elongation, PA~48deg, is 110 AU. Corresponding radii and orientations for the other sources are: DL Tau -- 250 AU at PA~84deg; DO Tau -- 350 AU at PA~160deg; AS 209 -- 290 AU at PA~138deg. RY Tau, DL Tau, and AS 209 show velocity gradients parallel to the elongation, suggesting that the circumstellar material is rotating. RY Tau and AS 209 also exhibit double-peaked spectra characteristic of a rotating disk. Line emission from DO Tau is dominated by high-velocity blue-shifted gas which complicates the interpretation. Nevertheless, there is in each case sufficient evidence to speculate that the circumstellar emission may arise from a protoplanetary disk similar to that from which our solar system formed.Comment: TeX file with associated macros, no figures; AJ in press. Also available as a compressed postscript file (including figures) by anonymous ftp at ftp://cougar.jpl.nasa.gov/pub/davidk/preprints/COinTTS.ps.

Imaging the Haro 6-10 Infrared Companion

We present an infrared imaging study of the low-mass pre-main-sequence binary system Haro 6-10. This system is one of a handful in which the optically visible primary has the characteristics of a normal T Tauri star, while the secondary is a so-called "infrared companion" (IRC), a strongly extincted object that emits most of its luminosity in the infrared. A speckle holographic technique was used to produce nearly diffraction-limited images on three nights over a 1 yr period starting in late 1997. The images show that the IRC is obscured and surrounded by a compact, irregular, and variable nebula. This structure is in striking contrast to the well-ordered edge-on disk associated with HK Tauri B, the extincted companion to another T Tauri star of similar age. A new, resolved intensity peak was found 0".4 southwest of the IRC. We suggest that it may represent light scattered by a clump of dusty material illuminated by starlight escaping along an outflow-carved cavity in the IRC envelope. The primary star became fainter and the companion became more extended during the observing period

A New Brown Dwarf Desert? A Scarcity of Wide Ultracool Binaries

We present the results of a deep-imaging search for wide companions to low-mass stars and brown dwarfs using NSFCam on IRTF. We searched a sample of 132 M7-L8 dwarfs to magnitude limits of $J \sim 20.5$ and $K \sim 18.5$, corresponding to secondary-primary mass ratios of $\sim 0.5$. No companions were found with separations between 2{\arcsec} to 31{\arcsec} ($\sim$40 AU to $\sim$1000 AU). This null result implies a wide companion frequency below 2.3% at the 95% confidence level within the sensitivity limits of the survey. Preliminary modeling efforts indicate that we could have detected 85% of companions more massive than $0.05 M_{\odot}$ and 50% above $0.03 M_{\odot}$.Comment: 27 pages, 8 figures, 3 tables: accepted to the Astronomical Journa

Millimeter-Wave Aperture Synthesis Imaging of Vega: Evidence for a Ring Arc at 95 AU

We present the first millimeter-wave aperture synthesis map of dust around a main sequence star. A 3'' resolution image of 1.3 mm continuum emission from Vega reveals a clump of emission 12'' from the star at PA 45 deg, consistent with the location of maximum 850 micron emission in a lower resolution JCMT/SCUBA map. The flux density is 4.0+/-0.9 mJy. Adjacent 1.3 mm peaks with flux densities 3.4+/-1.0 mJy and 2.8+/-0.9 mJy are located 14'' and 13'' from the star at PA 67 deg and 18 deg, respectively. An arc-like bridge connects the two strongest peaks. There is an additional 2.4 +/-0.8 mJy peak to the SW 11'' from the star at PA 215 deg and a marginal detection, 1.4+/-0.5 mJy, at the stellar position, consistent with photospheric emission. An extrapolation from the 850 micron flux, assuming F_{1.3mm-0.85mm} proportional to lambda^{-2.8}, agrees well with the total detected flux for Vega at 1.3 mm, and implies a dust emissivity index, beta, of 0.8. We conclude that we have detected all but a very small fraction of the dust imaged by SCUBA in our aperture synthesis map and that these grains are largely confined to segments of a ring of radius 95 AU.Comment: 4 pages, 1 figure, 1 table, accepted for publication in Astrophysical Journal Letter

Gluten contamination in the Canadian commercial oat supply

A growing body of evidence suggests that a majority of people with celiac disease and on a gluten-free diet can safely consume pure oats in moderate amounts; however, previous studies have indicated that the commercial oat supply in other countries, and in Canada to some extent, is contaminated with other grains. This study has confirmed that the commercial oat supply in Canada is heavily contaminated with gluten from other grains. Approximately 88% of the oat samples (n = 133) were contaminated above 20 mg kg−1 and there were no differences between the oat types tested. Only one gluten-free variety of oats was analysed and it consistently provided negative results in all analyses. It is difficult to determine where the contamination originates, but there are possibilities for cross-contamination in the field, in the transport of the grain, in the storage of the grain, and in the milling and packaging facilities. It is clear from this study that only those products that have been certified ‘pure’ oats would be appropriate for a gluten-free diet

A search for L dwarf binary systems

We present analysis of HST Planetary Camera images of twenty L dwarfs identified in the course of the Two Micron All-Sky Survey. Four of the targets have faint, red companions at separations between 0.07 and 0.29 arcseconds (1.6 to 7.6 AU). In three cases, the bolometric magnitudes of the components differ by less than 0.3 magnitudes. Since the cooling rate for brown dwarfs is a strong function of mass, similarity in luminosities implies comparable masses. The faint component in the 2M0850 system, however, is over 1.3 magnitudes fainter than the primary in the I-band, and ~0.8 magnitudes fainter in M(bol). Indeed, 2M0850B is ~0.8 magnitudes fainter in I than the lowest luminosity L dwarf currently known, while the absolute magnitude we deduce at J is almost identical with M_J for Gl 229B. Theoretical models indicate a mass ratio of \~0.75. The mean separation of the L dwarf binaries in the current sample is smaller by a factor of two than amongst M dwarfs. We discuss the implications of these results for the temperature scale in the L/T transition region and for the binary frequency amongst L dwarfs.Comment: 38 pages, 11 figures; accepted for A

NICMOS Imaging of the HR 4796A Circumstellar Disk

We report the first near infrared (NIR) imaging of a circumstellar annular disk around the young (~8 Myr), Vega-like star, HR 4796A. NICMOS coronagraph observations at 1.1 and 1.6 microns reveal a ring-like symmetrical structure peaking in reflected intensity 1.05 arcsec +/- 0.02 arcsec (~ 70 AU) from the central A0V star. The ring geometry, with an inclination of 73.1 deg +/- 1.2 deg and a major axis PA of 26.8 deg +/- 0.6 deg, is in good agreement with recent 12.5 and 20.8 micron observations of a truncated disk (Koerner, et al. 1998). The ring is resolved with a characteristic width of less than 0.26 arcsec (17 AU) and appears abruptly truncated at both the inner and outer edges. The region of the disk-plane inward of ~60 AU appears to be relatively free of scattering material. The integrated flux density of the part of the disk that is visible (greater than 0.65 arcsec from the star) is found to be 7.5 +/- 0.5 mJy and 7.4 +/- 1.2 mJy at 1.1 and 1.6 microns, respectively. Correcting for the unseen area of the ring yields total flux densities of 12.8 +/- 1.0 mJy and 12.5 +/- 2.0 mJy, respectively (Vega magnitudes = 12.92 /+- 0.08 and 12.35 +/-0.18). The NIR luminosity ratio is evaluated from these results and ground-based photometry of the star. At these wavelengths Ldisk(lambda)/L*(lambda) = 1.4 +/- 0.2E-3 and 2.4 +/- 0.5E-3, giving reasonable agreement between the stellar flux scattered in the NIR and that which is absorbed in the visible and re-radiated in the thermal infrared. The somewhat red reflectance of the disk at these wavelengths implies mean particle sizes in excess of several microns, larger than typical interstellar grains. The confinement of material to a relatively narrow annular zone implies dynamical constraints on the disk particles by one or more as yet unseen bodies.Comment: 14 pages, 1 figure for associated gif file see: http://nicmosis.as.arizona.edu:8000/AAS99/FIGURE1_HR4796A_ApJL.gif . Accepted 13 January 1999, Astrophyical Journal Letter

Complex Organic Materials in the HR 4796A Disk?

The red spectral shape of the visible to near infrared reflectance spectrum of the sharply-edged ring-like disk around the young main sequence star HR 4796A was recently interpreted as the presence of tholin-like complex organic materials which are seen in the atmosphere and surface of Titan and the surfaces of icy bodies in the solar system. However, we show in this Letter that porous grains comprised of common cosmic dust species (amorphous silicate, amorphous carbon, and water ice) also closely reproduce the observed reflectance spectrum, suggesting that the presence of complex organic materials in the HR 4796 disk is still not definitive.Comment: 6 pages, 3 figures; To be published in The Astrophysical Journal Letter