A scaling analysis of ozone photochemistry: II Investigation of the similarity relationship

International audienceThe similarity relationship for maximum ozone concentration as a function of initial precursor concentrations developed in the first article of this 2-part series exhibits a scale break, most easily seen after a Weibull transformation, which identifies a characteristic scale for ozone photochemistry. In this paper, we investigate the similarity relationship using simple semi-quantitative models and model output. From this investigation, we develop a set of properties characterizing ozone-precursor relationships. We find the scaling break is associated with a change in the temporal variability of ozone production. Finally, we examine a series of smog chamber experiments for evidence of a scaling break. We find the data support a slight break after suitable transformation. It is difficult to tell if the lack of distinct break is due to smog chamber experimental limitations, a bias in the test conditions or if the processes leading to the scaling break are overly enhanced by chemical mechanisms

The value-added statement: An appeal for standardisation

Owing to the absence of accounting standards for the preparation of a value-added statement (VAS), a large variety of methods are used in financial statements. In this study the published value-added statements (PVAS) of companies listed on the JSE Securities Exchange during the period 1976-2005 have been standardised by the Graduate School of Business of the University of Stellenbosch (USB) in order to quantify the differences between the standardised VAS (SVAS) and the PVAS. These differences consist of the inclusion of items that do not belong in the VAS, items that are erroneously allocated among the distribution to stakeholders, and interpretation differences in whether a certain item forms part of the calculation of value added or the distribution thereof. The greatest difference quantified was the overstatement of the distribution to government that amounted to 54.4% of total differences. For users, including government, to properly calculate and compare the value added of different business entities, a standard for the preparation and presentation of VAS ought to be published. In the South African context the need of a precise measurement of each business entity's contribution to the growth of the national economy is relevant, and this need should also be addressed.Value added, Gross Domestic Product, South Africa, financial statements

A scaling analysis of ozone photochemistry: I Model development

International audienceA scaling analysis has been used to capture the integrated behaviour of several photochemical mechanisms for a wide range of precursor concentrations and a variety of environmental conditions. The Buckingham Pi method of dimensional analysis was used to express the relevant variables in terms of dimensionless groups. These grouping show maximum ozone, initial NOx and initial VOC concentrations are made non-dimensional by the average NO2 photolysis rate (jav) and the rate constant for the NO-O3 titration reaction (kNO); temperature by the NO-O3 activation energy (ENO) and Boltzmann constant (k) and total irradiation time by the cumulative jav?t photolysis rate (?3). The analysis shows dimensionless maximum ozone concentration can be described by a product of powers of dimensionless initial NOx concentration, dimensionless temperature, and a similarity curve directly dependent on the ratio of initial VOC to NOx concentration and implicitly dependent on the cumulative NO2 photolysis rate. When Weibull transformed, the similarity relationship shows a scaling break with dimensionless model output clustering onto two straight line segments, parameterized using four variables: two describing the slopes of the line segments and two giving the location of their intersection. A fifth parameter is used to normalize the model output. The scaling analysis, similarity curve and parameterization appear to be independent of the details of the chemical mechanism, hold for a variety of VOC species and mixtures and a wide range of temperatures and actinic fluxes

Cross sections of proton-induced reactions on 152Gd, 155Gd and 159Tb with emphasis on the production of selected Tb radionuclides

Cross sections are presented for various Dy, Tb and Gd radionuclides produced in the proton bombardment of 159Tb as well as for the reactions 152Gd(p,4n)149Tb and 155Gd(p,4n)152Tb up to 66 MeV. The experimental excitation functions are compared with theoretical predictions by means of the geometrydependent hybrid (GDH) model as implemented in the code ALICE/ASH, as well as with values from the TENDL-2012 library and previous literature experimental data, where available. Physical yields have been derived for the production of some of the medically important radioterbiums, namely 149Tb (radionuclide therapy), 152Tb (PET) and 155Tb (SPECT). The indirect production of high-purity 155Tb via the decay of its precursor 155Dy is reported. The possibility of a large-scale production facility based on a commercial 70 MeV cyclotron is also discussed

A scaling analysis of ozone photochemistry

International audienceA scaling analysis has been used to capture the integrated behaviour of several photochemical mechanisms for a wide range of precursor concentrations and a variety of environmental conditions. The Buckingham Pi method of dimensional analysis was used to express the relevant variables in terms of dimensionless groups. These grouping show maximum ozone, initial NOx and initial VOC concentrations are made non-dimensional by the average NO2 photolysis rate (jav) and the rate constant for the NO?O3 titration reaction (kNO); temperature by the NO?O3 activation energy (ENO) and Boltzmann constant (k) and total irradiation time by the cumulative jav?t photolysis rate. The analysis shows dimensionless maximum ozone concentration can be described by a product of powers of dimensionless initial NOx concentration, dimensionless temperature, and a similarity curve directly dependent on the ratio of initial VOC to NOx concentration and implicitly dependent on the cumulative NO2 photolysis rate. When Weibull transformed, the similarity relationship shows a scaling break with dimensionless model output clustering onto two straight line segments, parameterized using four variables: two describing the slopes of the line segments and two giving the location of their intersection. A fifth parameter is used to normalize the model output. The scaling analysis, similarity curve and parameterization appear to be independent of the details of the chemical mechanism, hold for a variety of VOC species and mixtures and a wide range of temperatures and actinic fluxes

'A Monstrous Failure of Justice'?:Guantanamo Bay and National Security Challenges to Fundamental Human Rights

This article considers challenges to the existing international human rights regime in the post-9/11 era. It uses an interdisciplinary approach that brings together issues of politics and law by focussing on international legal provisions and setting them into the context of International Relations theory. The article examines the establishment of Guantanamo Bay as a detention centre for suspected terrorists captured in the 'war on terror' and focuses on violations of international human rights and humanitarian law in the name of national security. This article demonstrates that the wrangling over Guantanamo Bay is an important illustration of the complex interaction between interests and norms as well as law and politics in US policy making. The starting point is that politics and law are linked and cannot be seen in isolation from each other; the question that then arises is what kind of politics law can maintain. International Politics (2010) 47, 680-697. doi: 10.1057/ip.2010.25</p

No evidence of an 11.16 MeV 2+ state in 12C

An experiment using the 11B(3He,d)12C reaction was performed at iThemba LABS at an incident energy of 44 MeV and analyzed with a high energy-resolution magnetic spectrometer, to re-investigate states in 12C published in 1971. The original investigation reported the existence of an 11.16 MeV state in 12C that displays a 2+ nature. In the present experiment data were acquired at laboratory angles of 25-, 30- and 35- degrees, to be as close to the c.m. angles of the original measurements where the clearest signature of such a state was observed. These new low background measurements revealed no evidence of the previously reported state at 11.16 MeV in 12C

Food items consumed by students attending schools in different socio-economic areas in Cape Town, South Africa

Objective: We investigated the food consumption patterns of adolescent students at schools. Our findings are intended to reveal the overall nutritional quality of foods eaten by students at school, including foods brought to school and foods purchased at school. Methods: A questionnaire was completed by 476 students, mostly from grades 7 and 10, from 14 schools in Cape Town, South Africa. The schools were representative of the various ethnic groups and socioeconomic strata of the population. The questionnaire requested information on eating habits at school, foods brought to school and food purchases, and breakfast consumption before school. We also tested whether students knew which foods are healthy and which are less healthy choices. Results: The students were mostly 12 to 16 y of age (mean age 14.5 y). The large majority had breakfast before school (77.8%) and ate at school (79.7%). Food was brought to school by 41% to 56%, whereas 69.3% purchased food at school, mainly at the school store (tuck shop). Predefined “unhealthy” foods brought to school outnumbered “healthy” ones by 2 to 1. Among students who purchased food at school, 70.0% purchased no healthy items, whereas 73.2% purchased two or more unhealthy items. With six foods 84% of students correctly stated whether they were healthy or unhealthy; however, with cola drinks, samoosas (deep-fried pastry with spicy filling), and pies, only 47% to 61% knew that these were less healthy choices. Students’ scores on this question were unrelated to whether they purchased healthy or unhealthy foods. Students who attended schools of high socioeconomic status were twice as likely to bring food to school (64.7% versus 31.0%, P < 0.001), scored higher marks on the quiz of healthy versus unhealthy foods (P < 0.01), but were no more likely to purchase healthy food. Conclusions: The large majority of food eaten by adolescent students in Cape Town is classified as being unhealthy choices. This applies to foods brought to school and food purchases. Consideration needs to be given to policy measures to improve this situation and to improve education of students and their parents

Isotopic Production Cross Sections in Proton-Nucleus Collisions at 200 MeV

Intermediate mass fragments (IMF) from the interaction of $^{27}$Al, $^{59}$Co and $^{197}$Au with 200 MeV protons were measured in an angular range from 20 degree to 120 degree in the laboratory system. The fragments, ranging from isotopes of helium up to isotopes of carbon, were isotopically resolved. Double differential cross sections, energy differential cross sections and total cross sections were extracted.Comment: accepted by Phys. Rev.