Synchrotron oscillation damping due to beam-beam collisions

In DA{\Phi}NE, the Frascati e+/e- collider, the crab waist collision scheme has been successfully implemented in 2008 and 2009. During the collision operations for Siddharta experiment, an unusual synchrotron damping effect has been observed. Indeed, with the longitudinal feedback switched off, the positron beam becomes unstable with beam currents in the order of 200-300 mA. The longitudinal instability is damped by bringing the positron beam in collision with a high current electron beam (~2A). Besides, we have observed a shift of \approx 600Hz in the residual synchrotron sidebands. Precise measurements have been performed by using both a commercial spectrum analyzer and the diagnostics capabilities of the DA{\Phi}NE longitudinal bunch-by-bunch feedback. This damping effect has been observed in DA{\Phi}NE for the first time during collisions with the crab waist scheme. Our explanation is that beam collisions with a large crossing angle produce a longitudinal tune shift and a longitudinal tune spread, providing Landau damping of synchrotron oscillations.Comment: 3 pages, 5 figures, talk presented to IPAC'10 - Kyoto - May 24-28 201

Eye Tracking Impact on Quality-of-Life of ALS Patients

Chronic neurological disorders in their advanced phase are characterized by a progressive loss of mobility (use of upper and lower limbs), speech and social life. Some of these pathologies, such as amyotrophic lateral sclerosis and multiple sclerosis, are paradigmatic of these deficits. High technology communication instruments, such as eye tracking, can be an extremely important possibility to reintroduce these patients in their family and social life, in particular when they suffer severe disability. This paper reports and describes the results of an ongoing experimentation about Eye Tracking impact on the quality of life of amyotrophic lateral sclerosis patients. The aim of the experimentation is to evaluate if and when eye tracking technologies have a positive impact on patients' live

The use of ecosystem-based adaptation practices by smallholder farmers in Central America

There is growing interest in promoting the use of Ecosystem-based Adaptation (EbA) practices to help smallholder farmers adapt to climate change, however there is limited information on how commonly these practices are used by smallholder farmers and what factors influence their use. Using participatory mapping and field surveys, we examined the prevalence and characteristics of EbA practices on 300 smallholder coffee and maize farmers in six landscapes in Central America and explored the socioeconomic and biophysical factors associated with their use. The prevalence of individual EbA practices varied across smallholder farms. Common EbA practices included live fences, home gardens, shade trees in coffee plantations, and dispersed trees in maize fields. We found a mean of 3.8 EbA practices per farm. Factors that were correlated with the total number of EbA practices on farms included the mean area of coffee plantations, farmer age, farmer experience, the farm type and the landscape in which farms were located. Factors associated with the presence or characteristics of individual EbA practices included the size of coffee plantations, farmer experience, farmer education, land tenure, landscape and farm type. Our analysis suggests that many smallholder farmers in Central America are already using certain EbA practices, but there is still scope for greater implementation. Policy makers, donors and technicians can encourage the broader use of EbA by smallholder farmers by facilitating farmer-to-farmer exchanges to share knowledge on EbA implementation, assessing the effectiveness of EbA practices in delivering adaptation benefits, and tailoring EbA policies and programs for smallholder farmers in different socioeconomic and biophysical contexts. (Résumé d'auteur

Beclomethasone/formoterol versus budesonide/formoterol combination therapy in asthma

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Effect of age and asthma duration upon elastase and alpha1-antitrypsin levels in adult asthmatics

In asthmatic subjects an imbalance between elastase and alpha1-antitrypsin (alpha1-PI) exists. This study aims to evaluate whether ageing per se affects the levels of elastase. Both young and elderly asthmatics with comparable severity and duration of disease, as well as young and elderly healthy subjects, underwent an induced sputum procedure to measure levels of elastase and alpha1-PI. The percentage of sputum neutrophils and eosinophils was higher in young and elderly asthmatics than in young and elderly controls. The levels of both total and active elastase were significantly higher in young and elderly asthmatics than in young and elderly controls, and directly correlated with the percentage of neutrophils. In addition, in both young and elderly asthmatics the levels of total and active elastase were negatively correlated with forced expiratory volume in one second values, but positively correlated with the duration of the disease. This study indicates that ageing per se does not necessarily lead to a progressive elastase/alpha1-antitrypsin imbalance in asthma, and suggests that an important variable in the development of airway remodelling in both young and elderly asthmatics is represented by the duration of the disease

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