59,775 research outputs found
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
No full textThe prompt production of charmonium χ c and J / ψ states is studied in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the Large Hadron Collider. The χ c and J / ψ mesons are identified through their decays χ c → J / ψ γ and J / ψ → μ + μ - using 36 pb - 1 of data collected by the LHCb detector in 2010. The ratio of the prompt production cross-sections for χ c and J / ψ, σ (χ c → J / ψ γ) / σ (J / ψ), is determined as a function of the J / ψ transverse momentum in the range 2 < p T J / ψ < 15 GeV / c. The results are in excellent agreement with next-to-leading order non-relativistic expectations and show a significant discrepancy compared with the colour singlet model prediction at leading order, especially in the low p T J / ψ region
Relative flattening between velvet and matte 3D shapes: Evidence for similar shape-from-shading computations
No full textAmong other cues, the visual system uses shading to infer the 3D shape of objects. The shading pattern depends on the illumination and reflectance properties (BRDF). In this study, we compared 3D shape perception between identical shapes with different BRDFs. The stimuli were photographed 3D printed random smooth shapes that were either painted matte gray or had a gray velvet layer. We used the gauge figure task (J. J. Koenderink, A. J. van Doorn, & A. M. L. Kappers, 1992) to quantify 3D shape perception. We found that the shape of velvet objects was systematically perceived to be flatter than the matte objects. Furthermore, observers' judgments were more similar for matte shapes than for velvet shapes. Lastly, we compared subjective with veridical reliefs and found large systematic differences: Both matte and velvet shapes were perceived more flat than the actual shape. The isophote pattern of a flattened Lambertian shape resembles the isophote pattern of an unflattened velvet shape. We argue that the visual system uses a similar shape-from-shading computation for matte and velvet objects that partly discounts material propertiesIndustrial Design Engineerin
Wanted dead or alive : high diversity of macroinvertebrates associated with living and ’dead’ Posidonia oceanica matte
No full textThe Mediterranean endemic seagrass Posidonia
oceanica forms beds characterised by a dense leaf canopy
and a thick root-rhizome ‘matte’. Death of P. oceanica
shoots leads to exposure of the underlying matte, which
can persist for many years, and is termed ‘dead’ matte.
Traditionally, dead matte has been regarded as a degraded
habitat. To test whether this assumption was
true, the motile macroinvertebrates of adjacent living
(with shoots) and dead (without shoots) matte of
P. oceanica were sampled in four different plots located
at the same depth (5–6 m) in Mellieha Bay, Malta
(central Mediterranean). The total number of species
and abundance were significantly higher (ANOVA;
P<0.05 and P<0.01, respectively) in the dead matte
than in living P. oceanica matte, despite the presence of
the foliar canopy in the latter. Multivariate analysis
(MDS) clearly showed two main groups of assemblages,
corresponding to the two matte types. The amphipods
Leptocheirus guttatus and Maera grossimana, and the
polychaete Nereis rava contributed most to the dissimilarity
between the two different matte types. Several
unique properties of the dead matte contributing to the
unexpected higher number of species and abundance of
motile macroinvertebrates associated with this habitat
are discussed. The findings have important implications
for the conservation of bare P. oceanica matte, which
has been generally viewed as a habitat of low ecological
value.peer-reviewe
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
No full textFirst evidence of the B 0 → J / ψ ω decay is found and the B s 0 → J / ψ η and B s 0 → J / ψ η ′ decays are studied using a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV. The branching fractions of these decays are measured relative to that of the B 0 → J / ψ ρ 0 decay:frac(B (B 0 → J / ψ ω), B (B 0 → J / ψ ρ 0)) = 0.89 ± 0.19 (stat) - 0.13 + 0.07 (syst),frac(B (B s 0 → J / ψ η), B (B 0 → J / ψ ρ 0)) = 14.0 ± 1.2 (stat) - 1.5 + 1.1 (syst) - 1.0 + 1.1 (frac(f d, f s)),frac(B (B s 0 → J / ψ η ′), B (B 0 → J / ψ ρ 0)) = 12.7 ± 1.1 (stat) - 1.3 + 0.5 (syst) - 0.9 + 1.0 (frac(f d, f s)), where the last uncertainty is due to the knowledge of f d / f s, the ratio of b-quark hadronization factors that accounts for the different production rate of B 0 and B s 0 mesons. The ratio of the branching fractions of B s 0 → J / ψ η ′ and B s 0 → J / ψ η decays is measured to befrac(B (B s 0 → J / ψ η ′), B (B s 0 → J / ψ η)) = 0.90 ± 0.09 (stat) - 0.02 + 0.06 (syst)
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
No full textThis Letter reports a measurement of the CP violation observables SJ/ψK0S and CJ/ψK0S in the decay channel B0→J/ψK0S performed with 1.0 fb−1 of pp collisions at s√=7 TeV collected by the LHCb experiment. The fit to the data yields SJ/ψK0S=0.73±0.07(stat)±0.04(syst) and CJ/ψK0S=0.03±0.09(stat)±0.01(syst). Both values are consistent with the current world averages and within
expectations from the Standard Model
Letter from J. E. Gavin to Louis C. Cramton regarding Sale of Bright Angel Trail
No full textLetter from J. E. Gavin to Louis C. Cramton regarding the Bright Angel Trail controversy, including newspaper clipping
Matte - tap-hole clay - refractory brick interaction in a PGM smelter
No full textPaper written on project work carried out in partial fulfilment of BEng (Metallurgical
Engineering)Penetration of matte into tap-hole bricks causes detrimental refractory
wear, which can lead to furnace breakouts. The ability of the tap-hole clay
to form a protective layer on the brick, thereby limiting matte penetration
was investigated by examining the interaction between platinum group
metal (PGM) matte, tap-hole clay, and alumina-chrome refractory bricks
on a laboratory scale.
Samples containing clay and brick as well as samples containing clay,
brick, and matte were heated to different temperatures to establish the
clay-brick interaction and the extent of matte penetration. The greatest
degree of physical contact between the brick and clay was achieved at
curing temperatures of 600°C. Poor clay-brick contact was observed in the
sample that was heated to 900°C.
Matte displaced the clay in the clay-brick-matte sample that was
heated to 1350°C, with significant matte penetration into the brick. Less
matte penetration was observed when the clay-brick-matte sample was
heated to 1500°C. Less matte penetration was also observed in the claybrick-
matte sample in which the clay and brick were pre-baked at 800°C,
and the sample then reacted with matte at 1350°C.http://www.saimm.co.za/journal-papersam2016Mining Engineerin
Chromium deportment in copper matte equilibrated with CrxO-containing slag
No full textThesis (MScEng (Process Engineering))--University of Stellenbosch, 2006.An understanding of the behaviour of chromium in mattes equilibrated with
chrome-saturated slags is essential for the prediction and control of chromium
deportment in these melts. The main ore reserves of South Africa’s platinum
group metals (PGM) are associated with the Merensky and UG2 reefs of the
Bushveld Complex. The gradual depletion of the pyroxenitic Merensky reef over
the years has necessitated the PGM industry to exploit the underlying chromiterich
UG2 reef.
The problem with UG2 reef is that it contains significant amounts of chromium,
this being typically 5% (reported as Cr2O3) against <1% for the Merensky reef (in
concentrates). Chromium has a number of deleterious effects on base-metal
smelting processes. Under given conditions, it forms chromite spinels, which can
accumulate and, over a period of time, form undesirable build-ups resulting in
reduced furnace operational volume. The chromite spinels also tend to increase
slag viscosity, thereby impacting negatively on the slag/matte separation, which
leads to matte entrainment in slag. Moreover, high viscosities lead to problems
with tapping of the furnace melts. Finally it can be said that chromium that
deports to the matte during smelting will normally tend to precipitate as spinels
during subsequent converting, and lead to the formation of very stable and
unwanted slag foams in the converter.
In literature, there exists very little published work on the behaviour of
chromium in sulphur-saturated systems such as matte-smelting furnaces. The
few publications that exist in this area do not cover the effect of controlling all
the pertinent variables simultaneously on the behaviour of chromium in mattes
in equilibrium with chromium-containing slags. Hence the main focus of the oxygen fugacities on the mineralogical and deportment behaviour of chromium
in a matte-slag system.
All the three variables (temperature, oxygen fugacity (pO2), and sulphur fugacity
(pS2)) were investigated at three levels. Temperatures studied were 1300°C,
1400°C, and 1500°C. Oxygen and sulphur fugacities were established by
controlling the mix-ratios of purified carbon dioxide, carbon monoxide, sulphur
dioxide, and argon. Oxygen fugacities were maintained at 10-10atm, 10-8atm, and
10-6atm; whereas sulphur fugacities were maintained at 10-6atm, 10-4atm, and 10-
2atm. In order to investigate the effect of each of these three variables
(temperature, pS2, and pO2) at different levels of the other variables, a completely
randomised 33 full factorial experimental design was adopted.
The study revealed that chromium is generally present in matte as both
dissolved CrS and as precipitated oxidic and sulphidic chromium spinel phases.
It was shown that as the conditions become more oxidising (pO2 = 10-6atm), CrS
(which is soluble in matte) becomes a predominant phase, and as the conditions
become more reducing (pO2 = 10-10atm), the sulphospinel, daubreelite (FeCr2S4),
becomes a more predominant phase. Oxidic chromium spinels were found to be
present in matte under the more oxidising conditions (pO2 of 10-6atm) of this
investigation. The presence of the above-mentioned phases was confirmed using
X-ray diffraction.
Subject to the experimental conditions employed in this research, chromium was
found to partition the least to matte under the conditions of; low temperature,
high pO2, and low pS2. Conversely, chromium was found to partition the most to
matte under the conditions of; high temperature, low pO2, and high pS2
Acute Ethanol Administration Rapidly Increases Phosphorylation of Conventional Protein Kinase C in Specific Mammalian Brain Regions in Vivo
No full textBackground
Protein kinase C (PKC) is a family of isoenzymes that regulate a variety of functions in the central nervous system including neurotransmitter release, ion channel activity, and cell differentiation. Growing evidence suggests that specific isoforms of PKC influence a variety of behavioral, biochemical, and physiological effects of ethanol in mammals. The purpose of this study was to determine whether acute ethanol exposure alters phosphorylation of conventional PKC isoforms at a threonine 674 (p-cPKC) site in the hydrophobic domain of the kinase, which is required for its catalytic activity.
Methods
Male rats were administered a dose range of ethanol (0, 0.5, 1, or 2 g/kg, intragastric) and brain tissue was removed 10 minutes later for evaluation of changes in p-cPKC expression using immunohistochemistry and Western blot methods.
Results
Immunohistochemical data show that the highest dose of ethanol (2 g/kg) rapidly increases p-cPKC immunoreactivity specifically in the nucleus accumbens (core and shell), lateral septum, and hippocampus (CA3 and dentate gyrus). Western blot analysis further showed that ethanol (2 g/kg) increased p-cPKC expression in the P2 membrane fraction of tissue from the nucleus accumbens and hippocampus. Although p-cPKC was expressed in numerous other brain regions, including the caudate nucleus, amygdala, and cortex, no changes were observed in response to acute ethanol. Total PKC? immunoreactivity was surveyed throughout the brain and showed no change following acute ethanol injection
Measurement of the branching fraction
No full textThe B
0
s
→ J/ψK
0
S
branching fraction is measured in a data sample corresponding to 0.41 fb−1
of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to
the penguin contributions affecting the sin 2β measurement from B
0
→ J/ψK
0
S
. The time-integrated
branching fraction is measured to be B(B
0
s
→ J/ψK
0
S
) = (1.83±0.28)×10−5
. This is the most precise
measurement to date
- …
