Techniques for discovery and mass measurement using the boundary of many-body phase space

Despite several independent clues indicating new physics at the TeV scale, a lack of conclusive evidence for new physics so far suggests that future discoveries may only come from small numbers of new signal events. Therefore, it is crucial to find optimal methods with which to accurately measure the properties of new physics despite low statistics. In this scenario, the traditional kinematics variables such as edges and endpoints, which are merely one dimensional projections of the kinematic boundaries of a higher dimensional phase space, may not be the most efficient way to utilize limited information, especially in events consisting of cascade decays with large Standard Model backgrounds. In this dissertation, adopting a benchmark decay topology with one invisible particle in four-body final states proceeding through a sequence of two-body decays via intermediate resonances, I will focus on techniques which utilize the boundary of the allowed four-body phase space as well as the symmetric Gram determinant of the momenta of final state particles ∆₄, which is essential for parametrizing the phase space in a manifestly Lorentz-invariant way, to improve mass measurements and discovery sensitivity significantly over more conventional variable choices and techniques.Physic

Identifying Phase Space Boundaries with Voronoi Tessellations

Determining the masses of new physics particles appearing in decay chains is an important and longstanding problem in high energy phenomenology. Recently it has been shown that these mass measurements can be improved by utilizing the boundary of the allowed region in the fully differentiable phase space in its full dimensionality. Here we show that the practical challenge of identifying this boundary can be solved using techniques based on the geometric properties of the cells resulting from Voronoi tessellations of the relevant data. The robust detection of such phase space boundaries in the data could also be used to corroborate a new physics discovery based on a cut-and-count analysis.Comment: 48 pages, 23 figures, Journal-submitted versio

Enhancing the discovery prospects for SUSY-like decays with a forgotten kinematic variable

The lack of a new physics signal thus far at the Large Hadron Collider motivates us to consider how to look for challenging final states, with large Standard Model backgrounds and subtle kinematic features, such as cascade decays with compressed spectra. Adopting a benchmark SUSY-like decay topology with a four-body final state proceeding through a sequence of two-body decays via intermediate resonances, we focus our attention on the kinematic variable $\Delta_{4}$ which previously has been used to parameterize the boundary of the allowed four-body phase space. We highlight the advantages of using $\Delta_{4}$ as a discovery variable, and present an analysis suggesting that the pairing of $\Delta_{4}$ with another invariant mass variable leads to a significant improvement over more conventional variable choices and techniques.Comment: 20 pages, 13 figures. v2: matches published versio

Nanowrinkled Carbon Aerogels Embedded with FeN x Sites as Effective Oxygen Electrodes for Rechargeable Zinc-Air Battery.

Rational design of single-metal atom sites in carbon substrates by a flexible strategy is highly desired for the preparation of high-performance catalysts for metal-air batteries. In this study, biomass hydrogel reactors are utilized as structural templates to prepare carbon aerogels embedded with single iron atoms by controlled pyrolysis. The tortuous and interlaced hydrogel chains lead to the formation of abundant nanowrinkles in the porous carbon aerogels, and single iron atoms are dispersed and stabilized within the defective carbon skeletons. X-ray absorption spectroscopy measurements indicate that the iron centers are mostly involved in the coordination structure of FeN4, with a minor fraction (ca. 1/5) in the form of FeN3C. First-principles calculations show that the FeN x sites in the Stone-Wales configurations induced by the nanowrinkles of the hierarchically porous carbon aerogels show a much lower free energy than the normal counterparts. The resulting iron and nitrogen-codoped carbon aerogels exhibit excellent and reversible oxygen electrocatalytic activity, and can be used as bifunctional cathode catalysts in rechargeable Zn-air batteries, with a performance even better than that based on commercial Pt/C and RuO2 catalysts. Results from this study highlight the significance of structural distortions of the metal sites in carbon matrices in the design and engineering of highly active single-atom catalysts

Intramuscular electroporation with the pro-opiomelanocortin gene in rat adjuvant arthritis

Endogenous opioid peptides have an essential role in the intrinsic modulation and control of inflammatory pain, which could be therapeutically useful. In this study, we established a muscular electroporation method for the gene transfer of pro-opiomelanocortin (POMC) in vivo and investigated its effect on inflammatory pain in a rat model of rheumatoid arthritis. The gene encoding human POMC was inserted into a modified pCMV plasmid, and 0–200 μg of the plasmid-POMC DNA construct was transferred into the tibialis anterior muscle of rats treated with complete Freund's adjuvant (CFA) with or without POMC gene transfer by the electroporation method. The safety and efficiency of the gene transfer was assessed with the following parameters: thermal hyperalgesia, serum adrenocorticotropic hormone (ACTH) and endorphin levels, paw swelling and muscle endorphin levels at 1, 2 and 3 weeks after electroporation. Serum ACTH and endorphin levels of the group into which the gene encoding POMC had been transferred were increased to about 13–14-fold those of the normal control. These levels peaked 1 week after electroporation and significantly decreased 2 weeks after electroporation. Rats that had received the gene encoding POMC had less thermal hypersensitivity and paw swelling than the non-gene-transferred group at days 3, 5 and 7 after injection with CFA. Our promising results showed that transfer of the gene encoding POMC by electroporation is a new and effective method for its expression in vivo, and the analgesic effects of POMC cDNA with electroporation in a rat model of rheumatoid arthritis are reversed by naloxone

Pilot study of drinking water treatment with GAC, O-3/BAC and membrane processes in Kinmen Island, Taiwan

A study on advanced treatment of drinking water was conducted in a pilot scale plant in Tai Lake, Kinmen, Taiwan. The raw water contains a high concentration of disinfection by-product (DBP) precursors and causes serious odor problems. Chlorination of the raw water produced higher haloacetic acid formation potential (HAAFP) than trihalomethane formation potential (THMFP). Therefore, the high concentration of NOMs, which is the major source of DBP precursors, and the removal efficiencies of non-purgeable dissolved organic carbon (NPDOC), UV254, THMFP, HAAFP, 2-methylisoborneol (2-MIB), and trans-1, 10-dimethyl-trans-9-decalol (geosmin) were evaluated for both conventional and advanced water treatment processes. 2-MIB and geosmin can be removed efficiently by the GAC and O-3/BAC process, but bromo-THMs cannot. In addition, the removal efficiency of HAAFP was higher than that of THMFP by the GAC or O-3/BAC process. The ultrafiltration (UF)-nanofiltration (NF) combined process showed removal efficiencies for NPDOC, UV254, THMFP, HAAFP of 88.7%, 94%, 84.3% and 97.5%, respectively. This study found that the GAC or O-3/BAC process is a promising way to treat odor problems, and the UF-NF membrane process was one of the best available ways to remove NOMs and DBP formation potential. (C) 2010 Elsevier B.V. All rights reserved.Kinmen Water Work

The Effects of Perinatal Testosterone Exposure on the DNA Methylome of the Mouse Brain Are Late-Emerging

Background The biological basis for sex differences in brain function and disease susceptibility is poorly understood. Examining the role of gonadal hormones in brain sexual differentiation may provide important information about sex differences in neural health and development. Permanent masculinization of brain structure, function, and disease is induced by testosterone prenatally in males, but the possible mediation of these effects by long-term changes in the epigenome is poorly understood. Methods We investigated the organizational effects of testosterone on the DNA methylome and transcriptome in two sexually dimorphic forebrain regions—the bed nucleus of the stria terminalis/preoptic area and the striatum. To study the contribution of testosterone to both the establishment and persistence of sex differences in DNA methylation, we performed genome-wide surveys in male, female, and female mice given testosterone on the day of birth. Methylation was assessed during the perinatal window for testosterone\u27s organizational effects and in adulthood. Results The short-term effect of testosterone exposure was relatively modest. However, in adult animals the number of genes whose methylation was altered had increased by 20-fold. Furthermore, we found that in adulthood, methylation at a substantial number of sexually dimorphic CpG sites was masculinized in response to neonatal testosterone exposure. Consistent with this, testosterone\u27s effect on gene expression in the striatum was more apparent in adulthood. Conclusion Taken together, our data imply that the organizational effects of testosterone on the brain methylome and transcriptome are dramatic and late-emerging. Our findings offer important insights into the long-term molecular effects of early-life hormonal exposure