Vine age affects vine performance, grape and wine chemical and sensory composition of cv. Zinfandel from California

The wine industry regards old vines as nonpareil because of the vine’s decreased capacity to set and mature fruit, which results in superior wine quality. Here we report the viticultural, chemical, and sensory effects of vine age in Vitis vinifera L. cv. Zinfandel. Three treatments, Young vines (five to 12 years old), Control (repre sentative proportion of young to old vines in the block), and Old vines (40 to 60 years old) were established at an interplanted, dry farmed, Zinfandel vineyard block under consistent, industry standard, management practices in California over two consecutive vintages. Old vines produced, on average, 3.7 kg more fruit and more clusters per vine than Young vines (13.37 tons/ha and 6.52 tons/ha, respectively). While no differences in root distribution or architecture were found, Old vines displayed greater rooting depths (1.52 to 1.73 + m) than Young vines (1.40 to 1.52 + m). Wines from Young vines had lower pH, titratable acidity, and tannins than wines from Old vines, which in turn displayed a wider array and intensity of more complex aromas relative to Young vine wines. Overall, it is concluded that there is a potential for greater yield, rooting depths, and wine quality when extending the longevity of Zinfandel vineyards. These findings support maintaining old vine vineyards to increase tonnage without sacrific ing wine quality.EEA MendozaFil: Riffle, Vegas L. California Polytechnic State University. Wine and Viticulture Department; Estados UnidosFil: Alvarez Arredondo, Jocelyn. California Polytechnic State University. Wine and Viticulture Department; Estados UnidosFil: LoMonaco, Isabelle. California Polytechnic State University. Wine and Viticulture Department; Estados UnidosFil: Appel, Chip. California Polytechnic State University. Natural Resources Management and Environmental Sciences; Estados UnidosFil: Catania, Anibal Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Mendoza; ArgentinaFil: Dodson Peterson, Jean Catherine. California Polytechnic State University. Wine and Viticulture Department; Estados UnidosFil: Dodson Peterson, Jean Catherine. California Polytechnic State University. Horticulture and Crop Science Department; Estados UnidosFil: Dodson Peterson, Jean Catherine. Washington State University. Department of Viticulture and Enology. Wine Science Center; Estados UnidosFil: Casassa, Luis Federico. California Polytechnic State University. Wine and Viticulture Department; Estados Unido

Argon behaviour in an inverted Barrovian sequence, Sikkim Himalaya: the consequences of temperature and timescale on ⁴⁰Ar/³⁹Ar mica geochronology

40Ar/39Ar dating of metamorphic rocks sometimes yields complicated datasets which are difficult to interpret in terms of timescales of the metamorphic cycle. Single-grain fusion and step-heating data were obtained for rocks sampled through a major thrust-sense shear zone (the Main Central Thrust) and the associated inverted metamorphic zone in the Sikkim region of the eastern Himalaya. This transect provides a natural laboratory to explore factors influencing apparent 40Ar/39Ar ages in similar lithologies at a variety of metamorphic pressure and temperature (P–T) conditions. The 40Ar/39Ar dataset records progressively younger apparent age populations and a decrease in within-sample dispersion with increasing temperature through the sequence. The white mica populations span ~ 2–9 Ma within each sample in the structurally lower levels (garnet grade) but only ~ 0–3 Ma at structurally higher levels (kyanite-sillimanite grade). Mean white mica single-grain fusion population ages vary from 16.2 ± 3.9 Ma (2σ) to 13.2 ± 1.3 Ma (2σ) from lowest to highest levels. White mica step-heating data from the same samples yields plateau ages from 14.27 ± 0.13 Ma to 12.96 ± 0.05 Ma. Biotite yield older apparent age populations with mean single-grain fusion dates varying from 74.7 ± 11.8 Ma (2σ) at the lowest structural levels to 18.6 ± 4.7 Ma (2σ) at the highest structural levels; the step-heating plateaux are commonly disturbed. Temperatures > 600 °C at pressures of 0.4–0.8 GPa sustained over > 5 Ma, appear to be required for white mica and biotite ages to be consistent with diffusive, open-system cooling. At lower temperatures, and/or over shorter metamorphic timescales, more 40Ar is retained than results from simple diffusion models suggest. Diffusion modelling of Ar in white mica from the highest structural levels suggests that the high-temperature rocks cooled at a rate of ~ 50–80 °C Ma− 1, consistent with rapid thrusting, extrusion and exhumation along the Main Central Thrust during the mid-Miocene

Dust Filtration by Planet-Induced Gap Edges: Implications for Transitional Disks

By carrying out two-dimensional two-fluid global simulations, we have studied the response of dust to gap formation by a single planet in the gaseous component of a protoplanetary disk - the so-called "dust filtration" mechanism. We have found that a gap opened by a giant planet at 20 AU in a \alpha=0.01, \dot{M}=10^{-8} Msun/yr disk can effectively stop dust particles larger than 0.1 mm drifting inwards, leaving a sub-millimeter dust cavity/hole. However, smaller particles are difficult to filter by a planet-induced gap due to 1) dust diffusion, and 2) a high gas accretion velocity at the gap edge. An analytic model is also derived to understand what size particles can be filtered by the gap edge. Finally, with our updated understanding of dust filtration, we have computed Monte-Carlo radiative transfer models with variable dust size distributions to generate the spectral energy distributions (SEDs) of disks with gaps. By comparing with transitional disk observations (e.g. GM Aur), we have found that dust filtration alone has difficulties to deplete small particles sufficiently to explain the near-IR deficit of transitional disks, except under some extreme circumstances. The scenario of gap opening by multiple planets studied previously suffers the same difficulty. One possible solution is by invoking both dust filtration and dust growth in the inner disk. In this scenario, a planet induced gap filters large dust particles in the disk, and the remaining small dust particles passing to the inner disk can grow efficiently without replenishment from fragmentation of large grains. Predictions for ALMA have also been made based on all these scenarios. We conclude that dust filtration with planet(s) in the disk is a promising mechanism to explain submm observations of transitional disks but it may need to be combined with other processes (e.g. dust growth) to explain the near-IR deficit.Comment: 23 Pages, 11 figures, Accepted by Ap

Resolved Images of Large Cavities in Protoplanetary Transition Disks

Circumstellar disks are thought to experience a rapid "transition" phase in their evolution that can have a considerable impact on the formation and early development of planetary systems. We present new and archival high angular resolution (0.3" = 40-75 AU) Submillimeter Array (SMA) observations of the 880 micron dust continuum emission from 12 such transition disks in nearby star-forming regions. In each case, we directly resolve a dust-depleted disk cavity around the central star. Using radiative transfer calculations, we interpret these dust disk structures in a homogeneous, parametric model framework by reproducing their SMA visibilities and SEDs. The cavities in these disks are large (R_cav = 15-73 AU) and substantially depleted of small (~um-sized) dust grains, although their mass contents are still uncertain. The structures of the remnant material at larger radii are comparable to normal disks. We demonstrate that these large cavities are common among the millimeter-bright disk population, comprising at least 20% of the disks in the bright half of the millimeter luminosity (disk mass) distribution. Utilizing these results, we assess some of the physical mechanisms proposed to account for transition disk structures. As has been shown before, photoevaporation models do not produce the large cavity sizes, accretion rates, and disk masses representative of this sample. It would be difficult to achieve a sufficient decrease of the dust optical depths in these cavities by particle growth alone: substantial growth (to meter sizes or beyond) must occur in large (tens of AU) regions of low turbulence without also producing an abundance of small particles. Given those challenges, we suggest instead that the observations are most commensurate with dynamical clearing due to tidal interactions with low-mass companions --young brown dwarfs or giant planets on long-period orbits.Comment: ApJ, in pres

New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism

Background:\ud During much of the Late Cretaceous, a shallow, epeiric sea divided North America into eastern and western landmasses. The western landmass, known as Laramidia, although diminutive in size, witnessed a major evolutionary radiation of dinosaurs. Other than hadrosaurs (duck-billed dinosaurs), the most common dinosaurs were ceratopsids (large-bodied horned dinosaurs), currently known only from Laramidia and Asia. Remarkably, previous studies have postulated the occurrence of latitudinally arrayed dinosaur “provinces,” or “biomes,” on Laramidia. Yet this hypothesis has been challenged on multiple fronts and has remained poorly tested.\ud \ud Methodology/Principal Findings:\ud Here we describe two new, co-occurring ceratopsids from the Upper Cretaceous Kaiparowits Formation of Utah that provide the strongest support to date for the dinosaur provincialism hypothesis. Both pertain to the clade of ceratopsids known as Chasmosaurinae, dramatically increasing representation of this group from the southern portion of the Western Interior Basin of North America. Utahceratops gettyi gen. et sp. nov.—characterized by short, rounded, laterally projecting supraorbital horncores and an elongate frill with a deep median embayment—is recovered as the sister taxon to Pentaceratops sternbergii from the late Campanian of New Mexico. Kosmoceratops richardsoni gen. et sp. nov.—characterized by elongate, laterally projecting supraorbital horncores and a short, broad frill adorned with ten well developed hooks—has the most ornate skull of any known dinosaur and is closely allied to Chasmosaurus irvinensis from the late Campanian of Alberta.\ud \ud Conclusions/Significance:\ud Considered in unison, the phylogenetic, stratigraphic, and biogeographic evidence documents distinct, co-occurring chasmosaurine taxa north and south on the diminutive landmass of Laramidia. The famous Triceratops and all other, more nested chasmosaurines are postulated as descendants of forms previously restricted to the southern portion of Laramidia. Results further suggest the presence of latitudinally arrayed evolutionary centers of endemism within chasmosaurine ceratopsids during the late Campanian, the first documented occurrence of intracontinental endemism within dinosaurs

Shades of Xenophobia: In-Migrants and Immigrants in Mizamoyethu, Cape Town

L\u27hostilité des relations entre Africains du sud et immigrants africains est un fait ironique de la période post-apartheid. Mizamoyethu, établissement informel dans le quartier de Hout Bay, au Cap, n\u27est qu\u27un des nombreux centres à avoir connu la violence entre les indigènes et les étrangers. Après avoir souligné l\u27histoire, la géographie et la démographie de Mizamoyethu, ainsi qu\u27un compte-rendu du conflit, cet article identifie et explique les forces qui divisent la communauté. Le facteur le plus important s\u27est révélé être la concurrence pour les emplois, particulièrement dans l\u27industrie de la pêche locale. Dans le contexte d\u27une grande pauvreté matérielle et d\u27un chômage aux proportions inquiétantes, cette concurrence a alimenté la xénophobie et la violence qui en découlent. Les structures du conflit persisteront tant que ne changeront pas les circonstances matérielles, et toute tentative de résoudre le conflit restera, au mieux, un palliatif