Numerical Calculation of Coherent Synchrotron Radiation Effects Using TraFiC4

Coherent synchrotron radiation (CSR) occurs when short bunches travel on strongly bent trajectories. Its effects on high-quality beams can be severe and are well understood qualitatively. For quantitative results, however, one has to rely on numerical methods. There exist several simulation codes utilizing different approaches. We describe in some detail the code TraFiC4 developed at DESY for design and analysis purposes, which approaches the problem from first principles and solves the equations of motion either perturbatively or self-consistently. We present some calculational results and comparison with experimental data. Also, we give examples of how the code can be used to design beamlines with minimal emittance growth due to CSR

Observation of Target Electron Momentum Effects in Single-Arm M\o ller Polarimetry

In 1992, L.G. Levchuk noted that the asymmetries measured in M\o ller scattering polarimeters could be significantly affected by the intrinsic momenta of the target electrons. This effect is largest in devices with very small acceptance or very high resolution in laboratory scattering angle. We use a high resolution polarimeter in the linac of the polarized SLAC Linear Collider to study this effect. We observe that the inclusion of the effect alters the measured beam polarization by -14% of itself and produces a result that is consistent with measurements from a Compton polarimeter. Additionally, the inclusion of the effect is necessary to correctly simulate the observed shape of the two-body elastic scattering peak.Comment: 29 pages, uuencoded gzip-compressed postscript (351 kb). Uncompressed postscript file (898 kb) available to DECNET users as SLC::USER_DISK_SLC1:[MORRIS]levpre.p

Vergleichende Studie zur lokalen und systemischen Applikation von Aurintricarboxylsäure nach einer Durchtrennung des Sehnervs im Tiermodell

Eines der wesentlichen Ziele der Regenerationsforschung ist es, das Fortschreiten des retrograden Zelltodes aufzuhalten und die intrinsischen Funktionen der RGZ für den Beginn der Regeneration zu konservieren. Eine erfolgreiche Methode zur Neuroprotektion nach Axotomie von RGZ ist die intravitreale Injektion von Au-rintricarboxylsäure (ATA), In dieser Arbeit wurde untersucht, ob ATA auch bei systemischer Applikation, in Form von intraperitonealer (i.p.) und intravenöser (i.v.) Injektion neuroprotektiv auf die axotomierten RGZ wirkt. Die Ergebnisse lagen in den Bereichen, die auch ohne pharmakologische Interventionen oder durch reine Vehikel-Lösung erzielt wurden. Nach dem derzeitigen Kenntnisstand ist für eine neuroprotektive Behandlung im Auge eine lokale Applikation eines Pharmakons als die effektivste Methode zu bewerten. Bei systemischer Applikation eines Pharmakons scheinen zu viele Komponenten die Effektivität der applizierten Sub-stanz zu beeinflussen und letztlich zu verhindern

Facilitating Role Understanding and Collaboration Between Aspiring School Counselors and Principals

Using a convergent mixed-methods design, we investigated role understanding and collaboration between school counselors and principals. Specifically, this study situated aspiring school counselors and principals in a curriculum intervention on the role of their counterpart and then brought the two professions together in a collaborative powerful learning experience. The results of our pilot study demonstrate that both school counselor and educational leadership graduate students benefit from and value a presentation on roles of their opposite counterpart and the opportunity to practice collaboration in their graduate preparation programs

Controlling the configuration space topology of mechanisms

Linkages are mechanical devices constructed from rigid bars and freely rotating joints studied both for their utility in engineering and as mathematical idealizations in a number of physical systems. Recently, there has been a resurgence of interest in designing linkages to perform certain tasks from the physics community. We describe a method to design the topology of the configuration space of a linkage by first identifying the manifold of critical points, then perturbing around such critical configurations. We then demonstrate our procedure by designing a mechanism to gate the propagation of a soliton in a Kane-Lubensky chain of interconnected rotors

Impact of Optics on CSR-Related Emittance Growth in Bunch Compressor Chicanes

Abstract The dependence of emittance growth due to Coherent Synchrotron Radiation (CSR) in bunch compressor chicanes on optics has been noticed and empirically studied in the past. We revisit the subject, suggesting a model to explain slice emittance growth dependence on chicane optics. A simplified model to calculate projected emittance growth when it is mainly caused by transverse slice centroid offsets is presented. It is then used to find optimal compensation of centroid kicks in the single chicanes of a two-stage compression system by adjusting the phase advance of the transport in between and the ration of the compression factors

Acute Intermittent Hypoxia Does Not Impact Vascular Function in Young, Healthy Individuals

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Catalyst-Free Trifluoromethoxylation of Silyl Enol Ethers and Allyl Silanes with Bis(trifluoromethyl)peroxide

Radical trifluoromethoxylation is an attractive approach to prepare compounds featuring the important OCF3 group, however most existing methods have focused on aromatic substrates. Here, we report novel methodologies with alkenyl substrates employing bis(trifluoromethyl)peroxide (BTMP) as a practical and comparatively atom economical trifluoromethoxylating reagent. With silyl enol ether substrates, switching reaction solvent allows for the synthesis of either α-(trifluoromethoxy)ketone products or unprecedented alkenyl-OCF3 species. Furthermore, allyl silanes have been employed as substrates for the first time, affording allyl(trifluoromethyl)ether products in good yields. In each case, the methods operate at room temperature without large excesses of the alkene substrate while, in contrast to previous radical trifluoromethoxylation reactions, no catalyst, light or other activators are required