Impact of the Wiggler Coherent Synchrotron Radiation Impedance on the Beam Instability

Coherent Synchrotron Radiation (CSR) can play an important role by not only increasing the energy spread and emittance of a beam, but also leading to a potential instability. Previous studies of the CSR induced longitudinal instability were carried out for the CSR impedance due to dipole magnets. However, many storage rings include long wigglers where a large fraction of the synchrotron radiation is emitted. This includes high-luminosity factories such as DAPHNE, PEP-II, KEK-B, and CESR-C as well as the damping rings of future linear colliders. In this paper, the instability due to the CSR impedance from a wiggler is studied assuming a large wiggler parameter $K$. The primary consideration is a low frequency microwave-like instability, which arises near the pipe cut-off frequency. Detailed results are presented on the growth rate and threshold for the damping rings of several linear collider designs. Finally, the optimization of the relative fraction of damping due to the wiggler systems is discussed for the damping rings.Comment: 10 pages, 7 figure

O8-6 Participation in physical education, extra-curricular activities, and community sports among Irish adolescents with and without functional difficulties

BACKGROUND: Physical activity for adolescents with disabilities (AWD) are reported to have even greater health benefits than for adolescents without disabilities (AWoD). The settings for organised physical activity opportunities can include physical education, extra-curricular activities and community sport. Few studies have reported whether there are differences in participation in these settings between AWD and AWoD. The purpose of this study was to report differences in participation in organised physical activity between AWD and AWoD in Ireland. METHODS: Data, were disaggregated by disabilities, from the Irish children sport participation and physical activity 2018 study; a national representative self-report survey. Adolescents selected sports and physical activities they took part in the last 12 months in physical education, extra-curricular activities, and community sports. The child functioning module was completed with data coded according to the Washington group on disability statistics criteria. Data were stratified by gender and school level, with average scores of the number of activities analysed by T-Tests with Hedge's g, and no participation by Chi-square test of independence. RESULTS: The weighted sample included 6646 adolescents (53% female, 68% secondary level), of which 16% reported disabilities. Specific difficulties were sensory (4%), physical (1%), cognitive (7%), and behavioural (9%). More AWD reported they did not do any organised physical activities in all three settings (physical education, p = 0.029, extra-curriculum, p = >.001, community sport p = >.001) than AWoD. Adolescents with behavioural disabilities reported fewer types of physical education activities (males primary, p = .014, g =.31; secondary, p = .008, g = .24) and community sports (male primary, p = >.001, g = .49; female secondary, p = .027, g = .14) than adolescents without behavioural disabilities. CONCLUSIONS: Adolescents with behavioural difficulties were the largest disability group and reported fewer number of organised physical activities than AWoD; reinforcing actions are needed to increase perceived choice of activities. An alarming number of AWD reported no organised physical activities in all three settings. More thorough studies are required to investigate these reasons, and to provide support across settings, whereby differences in participation between adolescents with and without disabilities are not so profound

Secondary aerosol formation from atmospheric reactions of aliphatic amines

Although aliphatic amines have been detected in both urban and rural atmospheric aerosols, little is known about the chemistry leading to particle formation or the potential aerosol yields from reactions of gas-phase amines. We present here the first systematic study of aerosol formation from the atmospheric reactions of amines. Based on laboratory chamber experiments and theoretical calculations, we evaluate aerosol formation from reaction of OH, ozone, and nitric acid with trimethylamine, methylamine, triethylamine, diethylamine, ethylamine, and ethanolamine. Entropies of formation for alkylammonium nitrate salts are estimated by molecular dynamics calculations enabling us to estimate equilibrium constants for the reactions of amines with nitric acid. Though subject to significant uncertainty, the calculated dissociation equilibrium constant for diethylammonium nitrate is found to be sufficiently small to allow for its atmospheric formation, even in the presence of ammonia which competes for available nitric acid. Experimental chamber studies indicate that the dissociation equilibrium constant for triethylammonium nitrate is of the same order of magnitude as that for ammonium nitrate. All amines studied form aerosol when photooxidized in the presence of NOx with the majority of the aerosol mass present at the peak of aerosol growth consisting of aminium (R3NH+) nitrate salts, which repartition back to the gas phase as the parent amine is consumed. Only the two tertiary amines studied, trimethylamine and triethylamine, are found to form significant non-salt organic aerosol when oxidized by OH or ozone; calculated organic mass yields for the experiments conducted are similar for ozonolysis (15% and 5% respectively) and photooxidation (23% and 8% respectively). The non-salt organic aerosol formed appears to be more stable than the nitrate salts and does not quickly repartition back to the gas phase

Tackling unemployment in China: state capacity and governance issues

This paper considers China's state capacity and changing governance as revealed through its policies to tackle unemployment. Despite high levels of growth, economic restructuring has resulted in rising unemployment over the last decade. The Chinese state has been able to manage job losses from state enterprises, demonstrating some state capacity in relation to this sector and some persistent command economy governance mechanisms. However both design and implementation of policies to compensate and assist particular groups among the unemployed have been shaped by weak state capacity in several other areas. First, capacity to gather accurate employment data is limited, meaning local and central governments do not have a good understanding of the extent and nature of unemployment. Second, the sustainability of supposedly mandatory unemployment insurance schemes is threatened by poor capacity to enforce participation. Third, poor central state capacity to ensure local governments implement policies effectively leads to poor unemployment insurance fund capacity, resulting in provision for only a narrow segment of the unemployed and low quality employment services. Although the adoption of unemployment insurance (and its extension to employers and employees in the private sector), the introduction of a Labour Contract Law in 2007, and the delivery of employment services by private businesses indicate a shift towards the use of new governance mechanisms based on entitlement, contract and private sector delivery of public-sector goods, that shift is undermined by poor state capacity in relation to some of these new mechanisms

Secondary organic aerosol formation from isoprene photooxidation under high-NO_x conditions

The oxidation of isoprene (2-methyl-1,3-butadiene) is known to play a central role in the photochemistry of the troposphere, but is generally not considered to lead to the formation of secondary organic aerosol (SOA), due to the relatively high volatility of known reaction products. However, in the chamber studies described here, we measure SOA production from isoprene photooxidation under high-NO_x conditions, at significantly lower isoprene concentrations than had been observed previously. Mass yields are low (0.9–3.0%), but because of large emissions, isoprene photooxidation may still contribute substantially to global SOA production. Results from photooxidation experiments of compounds structurally similar to isoprene (1,3-butadiene and 2- and 3-methyl-1-butene) suggest that SOA formation from isoprene oxidation proceeds from the further reaction of first-generation oxidation products (i.e., the oxidative attack of both double bonds). The gas-phase chemistry of such oxidation products is in general poorly characterized and warrants further study

Calculation of the Coherent Synchrotron Radiation Impedance from a Wiggler

Most studies of Coherent Synchrotron Radiation (CSR) have only considered the radiation from independent dipole magnets. However, in the damping rings of future linear colliders, a large fraction of the radiation power will be emitted in damping wigglers. In this paper, the longitudinal wakefield and impedance due to CSR in a wiggler are derived in the limit of a large wiggler parameter $K$. After an appropriate scaling, the results can be expressed in terms of universal functions, which are independent of $K$. Analytical asymptotic results are obtained for the wakefield in the limit of large and small distances, and for the impedance in the limit of small and high frequencies.Comment: 10 pages, 8 figure

On the implications of aerosol liquid water and phase separation for modeled organic aerosol mass

Water is an important component of PM2.5 Many traditional SOA species are highly soluble and thus can be considered extractable Water can influence the partitioning of compounds traditionally considered insoluble in models Organic aerosol takes up water according to RH Organic aerosol interacts with inorganic water Deviations in ideality (solubility) must be considered