3,211 research outputs found
Effect of Fungicide Spray Cover on Botrytis Cinerea Infection in Grape Bunches
The effect of fungicide spray cover on Botrytis cinerea infection in grape bunches was determined. Bunches were sprayed at pea size and bunch closure with different volumes of a mixture of fenhexamid and a yellow fluorescent pigment, and the percentage fluorescent pigment coverage on pedicels was determined. Bunches were subsequently dusted with dry airborne conidia of B. cinerea in a settling tower and incubated for 24 h at high relative humidity (98%). Infection was determined by estimating the amount of B. cinerea infections on susceptible bunch parts (pedicel, receptacle and rachis) with isolations onto paraquat (herbicide) and Kerssies (B. cinerea selective) mediums. Linear regressions for the part × stage combinations of percentage B. cinerea incidence on different bunchparts were fitted on mean coverage levels. An increase in spray cover caused linear reductions in levels of B. cinerea on bunch parts. Higher B. cinerea incidences were recorded at pea size. Furthermore, higher B. cinerea incidences were found on paraquat medium for both stages, than on Kerssies medium. The information gathered from this study will be used to facilitate future determination of minimum effective coverage levels for effective B. cinerea control in grape bunches
Towards an improved understanding of eta --> gamma^* gamma^*
We argue that high-quality data on the reaction
will allow one to determine the double off-shell form factor in a model-independent way with controlled accuracy. This is
an important step towards a reliable evaluation of the hadronic light-by-light
scattering contribution to the anomalous magnetic moment of the muon. When
analyzing the existing data for in the range of
total energies , we demonstrate that the
double off-shell form factor is
consistent with the commonly employed factorization ansatz at least for
, if the effect of the meson is taken into account.
However, better data are needed to draw firm conclusions.Comment: 7 pages, 3 figure
Enrolment in Medieval English Government: Sickness or Cure?
In the Middle Ages, rolls were ubiquitous as a writing support. While scholars have long examined the texts and images on rolls, they have rarely taken the manuscripts themselves into account. This volume readdresses this imbalance by focusing on the materiality and various usages of rolls in late medieval England and France. Researchers from England, France, Germany and Singapore demonstrate in 11 contributions how this approach can increase our understanding of the rolls and their contents, as well as the contexts in which they were produced and used
The galactic center black hole as a possible retro-lens for the S2 orbiting star
Holz & Wheeler (\cite{hw}) have recently proposed that a Schwarzschild black
hole may act as a retro-lens which, if illuminated by a powerful light source,
deflects light ray paths to large bending angles and a series of luminous arcs
(or rings in the case of aligned objects) centered on the black hole may form.
Obviously, the most convenient geometry to get retro-lensing images would be
that of a very bright star close to a massive black hole, say the putative
M black hole at the galactic center. Recent
observations of the galactic center region in the -band have revealed the
presence of a very bright main sequence star (labelled S2) with mass
M orbiting at close distance (130-1900 AU) from Sgr A. The
relatively vicinity of S2 to the central massive black hole may offer a unique
laboratory to test the formation of retro-lensing images. The next generation
of space-based telescopes in the -band (like NGST) may have high enough
limiting magnitude necessary to observe such retro-lensing images.Comment: 4 pages, 2 Postscript figures, accepted for pubblications on
Astronomy and Astrophysic
Spillover Effects in Police Use of Force
We study the link between officer injuries-on-duty and the force-use of their peers using a network of officers who, through a random lottery, began the police academy together. We find that peer injuries-on-duty increase the probability of using force by 7%. The effect is concentrated in a narrow time window near the event and is not associated with significantly lower injury risk to the officer. Complaints of improper searches and failure to provide service also increase after peer injuries, suggesting that the increase in force might be driven by heightened risk aversion
SAE Small Vehicle Lifts
The SAE (Society for Automotive Engineers) vehicle teams at Cal Poly need an easy way to access the undersides of their vehicles to facilitate maintenance and servicing. The purpose of this project was to provide a solution that could lift the vehicles effectively and safely from above so that the underside of the vehicles can be accessed, as well as elevating the vehicles to an ergonomic working height. Design specifications were determined based off each vehicle’s requirements in addition to what the team intends to do with their suspended vehicle. After several concept iterations, the team decided to purchase an engine hoist and replace the hydraulic cylinder with a fixed tube and construct a custom transmission thereby turning the engine hoist into a crane mechanism that can be operated easily without concerns of reliability. The team constructed a total of three lifts, each with different specifications, for the Baja, Formula, and F2000 cars. Material testing was done to verify that the unknown material of the purchased lifts was strong enough to support the loading, as well as final load testing by lifting a vehicle to its designed height
Holocene Dynamics of Temperate Rainforests in West-Central Patagonia
Analyses of long-term ecosystem dynamics offer insights into the conditions that have led to stability vs. rapid change in the past and the importance of disturbance in regulating community composition. In this study, we (1) used lithology, pollen, and charcoal data from MallÃn Casanova (47°S) to reconstruct the wetland, vegetation, and fire history of west-central Patagonia; and (2) compared the records with independent paleoenvironmental and archeological information to assess the effects of past climate and human activity on ecosystem dynamics. Pollen data indicate that Nothofagus-Pilgerodendronforests were established by 9,000 cal yr BP. Although the biodiversity of the understory increased between 8,480 and 5,630 cal yr BP, forests remained relatively unchanged from 9,000 to 2,000 cal yr BP. The charcoal record registers high fire-episode frequency in the early Holocene followed by low biomass burning between 6,500 and 2,000 cal yr BP. Covarying trends in charcoal, bog development, and Neoglacial advances suggest that climate was the primary driver of these changes. After 2,000 cal yr BP, the proxy data indicate (a) increased fire-episode frequency; (b) centennial-scale shifts in bog and forest composition; (c) the emergence of vegetation-fire linkages not recorded in previous times; and (d) paludification in the last 500 years possibly associated with forest loss. Our results therefore suggest that Nothofagus-Pilgerodendrondominance was maintained through much of the Holocene despite long-term changes in climate and fire. Unparalleled fluctuations in local ecosystems during the last two millennia were governed by disturbance-vegetation-hydrology feedbacks likely triggered by greater climate variability and deforestation
The Clustering of Massive Halos
The clustering properties of dark matter halos are a firm prediction of
modern theories of structure formation. We use two large volume,
high-resolution N-body simulations to study how the correlation function of
massive dark matter halos depends upon their mass and formation history. We
find that halos with the lowest concentrations are presently more clustered
than those of higher concentration, the size of the effect increasing with halo
mass; this agrees with trends found in studies of lower mass halos. The
clustering dependence on other characterizations of the full mass accretion
history appears weaker than the effect with concentration. Using the integrated
correlation function, marked correlation functions, and a power-law fit to the
correlation function, we find evidence that halos which have recently undergone
a major merger or a large mass gain have slightly enhanced clustering relative
to a randomly chosen population with the same mass distribution.Comment: 10 pages, 8 figures; text improved, references and one figure added;
accepted for publication in Ap
- …