1,414 research outputs found
Paula Rego: printmaker
Full text link‘Paula Rego: Printmaker’ is an extended essay commissioned from the author by Marlborough Fine Art and Talbot Rice Museum, Edinburgh, for the illustrated catalogue to accompany the touring exhibition of Rego’s graphic work.
My essay reveals Rego’s working method, and places her prints within the overall context of her practice. The essay contains much original research evidenced over a 20-year period of collaboration with the artist, including first hand observation and hitherto unpublished stage proofs revealing the progression and development of images from first stage to final print
Evidence for the decay B0→J/ψω and measurement of the relative branching fractions of meson decays to J/ψη and J/ψη′
Full text linkFirst 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)
Debates over Palaeolithic chronology - the reliability of C-14 is confirmed
No full textThe debate about the complex issues of human development during the Middle to Upper Palaeolithic transition period (45-35 ka BP) has been hampered by concerns about the reliability of the radiocarbon dating method. Large C-14 anomalies were postulated and radiocarbon dating was considered flawed. We show here that these issues are no longer relevant, because the large anomalies are artefacts beyond plausible physical limits for their magnitude. Previous inconsistencies between C-14 radiocarbon datasets have been resolved, and a new radiocarbon calibration curve, IntCal09 (Reimer et al., 2009), was created. Improved procedures for bone collagen extraction and charcoal pre-treatment generally result in older ages, consistent with independently dated time markers. (C) 2012 Elsevier Ltd. All rights reserved.</p
Measurement of the ratio of prompt χ c to J / ψ production in pp collisions at √s = 7 TeV
Full text linkThe 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
Natural mummies from Predynastic Egypt reveal the world’s earliest figural tattoos
Full text linkThe application of tattoos to the human body has enjoyed a long and diverse history in many ancient cultures. At present, the oldest surviving examples are the mainly geometric tattoos on the individual known as Ötzi, dating to the late 4th millennium BCE, whose skin was preserved by the ice of the Tyrolean Alps. In the Egyptian Nile valley, the arid climate has also promoted extensive soft tissue preservation. Here we report on the tattoos found during the examination of two of the best preserved naturally mummified bodies from Egypt’s Predynastic (c. 4000-3100 BCE) period, making them the earliest extant examples from the Nile Valley. Figural tattoos that mirror motifs found in Predynastic art were observed on the right arm of one male and the right arm and shoulder of one female, demonstrating conclusively that tattooing was practiced in prehistoric Egypt. These findings overturn the circumstantial evidence of the artistic record that previously suggested only females were tattooed for fertility or even erotic reasons. Radiocarbon testing and datable iconographic parallels for the motifs indicate that these tattooed individuals are nearly contemporaneous with the Iceman, positioning them amongst the bearers of some of the oldest preserved tattoos in the world. At over five thousand years of age, they push back the evidence for tattooing in Africa by a millennium and provide new insights into the range of potential uses of tattoos in pre-literate societies by both sexes, revealing new contexts for exploring the visual language of prehistoric times
Testing solar forcing of pervasive Holocene climate cycles
No full textThe temporal and spatial extent of Holocene climate change is an area of considerable uncertainty, with solar forcing recently proposed to be the origin of cycles identified in the North Atlantic region. To address these issues we have developed an annually resolved record of changes in Irish bog tree populations over the last 7468 years which, together with radiocarbon-dated bog and lake-edge populations, extend the dataset back to 9000 yr ago. The Irish trees underpin the internationally accepted radiocarbon calibration curve, used to derive a proxy of solar activity, and allow us to test solar forcing of Holocene climate change. Tree populations and age structures provide unambiguous evidence of major shifts in Holocene surface moisture, with a dominant cyclicity of 800 yr, similar to marine cycles in the North Atlantic, indicating significant changes in the latitude and intensity of zonal atmospheric circulation across the region. The cycles, however, are not coherent with changes in solar activity (both being on the same absolute timescale), indicating that Holocene North Atlantic climate variability at the millennial and centennial scale is not driven by a linear response to changes in solar activity
Achievement spirals: understanding academic achievement differences in an urban school
No full textThis case study examined achievement differences in an urban school where student achievement was high in K-5 but declined in Grades 6-8. School- and classroom-level factors, such as the principal’s leadership, school culture, school vision, qualified teachers, use of student performance data, curriculum and instructional practices, and external factors such as parent and community partnerships were examined. Quantitative data were analyzed to identify differences in student achievement between transfer students from a feeder school and nontransfer students. Where differences existed, multiple and fixed effect regressions identified the most likely predictor(s) of the differences. Analysis identified a combination of contributing student-level factors: special education, Limited English Proficiency, transfer, race/ethnicity, and poverty, leading to the conclusion that the problem stemmed from a combination of factors. While transfer students contributed to depressed academic achievement in Mathematics, the decline had begun in Grade 4, before the merger of students. Thus, it was concluded that transfer students were not the sole cause of the overall decline in performance. Similar findings for Language Arts Literacy led to the same conclusion. Analysis of qualitative data indicated that the effectiveness of the school was dependent on several key factors: the cited student-level factors, consistent and stable leadership, accessible resources (defined as support and time), teacher expectations, lower curricular rigor, and parental involvement. The effectiveness of the school was dependent on perceived accessible resources, such as support and time, and effective stable leadership. Inconsistent guidance and planning were reflected in the instability of leadership at the middle school level, inadequate time to plan and collaborate, pressure of accountability and minimal parental involvement. This challenge created an environment in which meeting the high expectations and accountability standards seemed unattainable and insurmountable, producing a less effective school. The study provides important quantitative and qualitative evidence of school and student factors that can contribute to decline in achievement at an urban middle school, especially with regard to problems with the transfer component of No Child Left Behind. It was concluded that factors affecting student achievement are multidimensional and that solutions are very difficult but not insurmountable.Ph. D.Includes bibliographical referencesIncludes vitaby Paula J. Gordo
Measurement of the time-dependent CP asymmetry in B0 -> J/ψ KS0 decays
Full text linkThis 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
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
Full text linkMeasurement of the mixing-induced CP-violating phase phi_s in Bs decays is of prime importance in probing new physics. Here 7421 +/- 105 signal events from the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A time-dependent fit to the data yields a value of phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard Model expectation. No evidence of direct CP violation is found
Measurement of the branching fraction
Full text linkThe 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
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