Recent Beam-Beam Effects at VEPP-2000 and VEPP-4M

Budker INP hosts two e+e- colliders, VEPP-4M operating in the beam energy range of 1-5.5 GeV and the low-energy machine VEPP-2000, collecting data at 160-1000 MeV per beam. The latter uses a novel concept of round colliding beams. The paper presents an overview of observed beam-beam effects and obtained luminosities.Comment: Presented at the ICFA Mini-Workshop on Beam-Beam in Hadron Colliders, CERN, Geneva, Switzerland, 18-22 March 201

The status of the energy calibration, polarization and monochromatization of the FCC-ee

The Future Circular electron-positron Collider, FCC- ee, is designed for unprecedented precision for particle physics experiments from the Z-pole up to above the top-pair-threshold, corresponding to a beam energy range from 45.6 to 182.5 GeV. Performing collisions at various particle-physics resonances requires precise knowledge of the centre-of-mass energy (ECM) and collision boosts at all four interaction points. Measurement of the ECM by resonant depolarization of transversely polarized pilot bunches in combination with a 3D polarimeter, aims to achieve a systematic uncertainty of 4 and 100 keV for the Z-pole and W-pair-threshold energies respectively. The ECM itself depends on the RF-cavity locations, beamstrahlung, longitudinal impedance, the Earth’s tides, opposite sign dispersion and possible collision offsets. Application of monochromatization schemes are envisaged at certain beam energies to reduce the energy spread. The latest results of studies of the energy calibration, polarization and monochromatization are reported here

Microbial community composition in sediments resists perturbation by nutrient enrichment

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in The ISME Journal 5 (2011): 1540–1548, doi:10.1038/ismej.2011.22.Functional redundancy in bacterial communities is expected to allow microbial assemblages to survive perturbation by allowing continuity in function despite compositional changes in communities. Recent evidence suggests, however, that microbial communities change both composition and function as a result of disturbance. We present evidence for a third response: resistance. We examined microbial community response to perturbation caused by nutrient enrichment in salt marsh sediments using deep pyrosequencing of 16S rRNA and functional gene microarrays targeting the nirS gene. Composition of the microbial community, as demonstrated by both genes, was unaffected by significant variations in external nutrient supply, despite demonstrable and diverse nutrient–induced changes in many aspects of marsh ecology. The lack of response to external forcing demonstrates a remarkable uncoupling between microbial composition and ecosystem-level biogeochemical processes and suggests that sediment microbial communities are able to resist some forms of perturbation.Funding for this research came from NSF(DEB-0717155 to JEH, DBI-0400819 to JLB). Support for the sequencing facility came from NIH and NSF (NIH/NIEHS-P50-ES012742-01 and NSF/OCE 0430724-J Stegeman PI to HGM and MLS, and WM Keck Foundation to MLS). Salary support provided from Princeton University Council on Science and Technology to JLB. Support for development of the functional gene microarray provided by NSF/OCE99-081482 to BBW. The Plum Island fertilization experiment was funded by NSF (DEB 0213767 and DEB 0816963)

Electric dipole moments and the search for new physics

Static electric dipole moments of nondegenerate systems probe mass scales for physics beyond the Standard Model well beyond those reached directly at high energy colliders. Discrimination between different physics models, however, requires complementary searches in atomic-molecular-and-optical, nuclear and particle physics. In this report, we discuss the current status and prospects in the near future for a compelling suite of such experiments, along with developments needed in the encompassing theoretical framework.Comment: Contribution to Snowmass 2021; updated with community edits and endorsement

FCC-ee Energy Calibration and Polarization

The Future Circular electron-positron Collider, FCC-ee, is designed for unprecedented precision for particle physics experiments from the Z-pole to above the top-pair-threshold. This demands a precise knowledge of the centre-of-mass energy (ECM) and collision boosts at all four interaction points and all operation energies. From the Z-pole to the W-pair-region, determining the average beam energies is foreseen using resonant depolarization, with a precision of a few keV, using transversely polarized non-colliding pilot bunches. While wigglers are foreseen to improve the polarization time, misalignment and field errors can limit the achievable polarization level, and might alter the relationship between the resonant depolarization frequency and the beam energies. Strong synchrotron radiation losses range from 40 MeV per turn at the Z-pole, to 10 GeV per turn at the highest beam energy of 182.5 GeV can lead to different ECM and boosts for each interaction point. Beamstrahlung generates further energy losses. Other sources of ECM bias stem from collision offsets and must be controlled. A first evaluation has been published in 2019 with promising results. Further studies are ongoing in the framework of the Feasibility Study to be delivered in 2025 and a first set of further improvements on energy calibration, polarization and monochromatization are presented here

Mechanism for Prevention of Alcohol-Induced Liver Injury by Dietary Methyl Donors

Alcohol-induced liver injury (ALI) has been associated with, among other molecular changes, abnormal hepatic methionine metabolism, resulting in decreased levels of S-adenosylmethionine (SAM). Dietary methyl donor supplements such as SAM and betaine mitigate ALI in animal models; however, the mechanisms of protection remain elusive. It has been suggested that methyl donors may act via attenuation of alcohol-induced oxidative stress. We hypothesized that the protective action of methyl donors is mediated by an effect on the oxidative metabolism of alcohol in the liver. Male C57BL/6J mice were administered a control high-fat diet or diet enriched in methyl donors with or without alcohol for 4 weeks using the enteral alcohol feeding model. As expected, attenuation of ALI and an increase in reduced glutathione:oxidized glutathione ratio were achieved with methyl donor supplementation. Interestingly, methyl donors led to a 35% increase in blood alcohol elimination rate, and while there was no effect on alcohol metabolism in the stomach, a profound effect on liver alcohol metabolism was observed. The catalase-dependent pathway of alcohol metabolism was induced, yet the increase in CYP2E1 activity by alcohol was blunted, which may be mitigating production of oxidants. Additional factors contributing to the protective effects of methyl donors in ALI were increased activity of low- and high-Km aldehyde dehydrogenases leading to lower hepatic acetaldehyde, maintenance of the efficient mitochondrial energy metabolism, and promotion of peroxisomal β-oxidation. Profound changes in alcohol metabolism represent additional important mechanism of the protective effect of methyl donors in ALI

Real Exchange Rates and Time-Varying Trade Costs

This paper re-examines the empirical modeling of Purchasing Power Parity (PPP) deviations in the presence of commodity market frictions. First, we show that a specific type of smooth transition models can closely approximate the functional form of the theoretical adjustment mechanism derived by Dumas (1992) [Dynamic Equilibrium and the Real Exchange Rate in a Spatially Separated World, Review of Financial Studies,5:2153–180] for the case of constant as well as changing trade costs. Second, we develop, for the first time, an empirical model of the real exchange rate which allows for changes in the degree of market integration. By employing a long span of data on the Dollar-Sterling real exchange rate and a micro-founded proxy for trade frictions, we provide novel evidence of a significant relationship between the persistence of the real exchange rate and the level of trade costs. This finding suggests that both the difficulty of detecting PPP and the extend of Rogoff’s puzzle vary over time with the degree of trade restrictiveness. Finally, we highlight policy repercussions of our results

Polarization in SuperB

SuperB, the 2nd-generation B-Factory with a luminosity of 10{sup 36}/cm{sup 2}/s proposed for LNF, is being designed from the start to be capable of providing a spin-polarized electron beam in the low-energy ring (LER) with longitudinal polarization at the interaction point. Due to the high luminosity at moderate beam current the beam lifetime is short (a few minutes), and a polarized injector will be used. Spin rotators have been designed and the equilibrium polarization evaluated. It will be shown that an average polarization of about 70% can be expected