Time Resolution Measurements on SiPM for High Energy Physics Experiments

Scintillator detector have been used in a wide range of experiments in different areas: Nuclear and High Energy Physics, Medicine, and Radiation Security among others. It is common to use scintillator counters coupled to Photomultiplier Tubes (PMT) as a read out detectors. Nowadays, there has been a great interest in using the Silicon Photomultipliers (PMSi) as a replacement for PMT's due to their high photon detection efficiency (PDE) and their high single photon time resolution (SPTR). The fast the signal is detected, the whole detection system will be useful to search for new physics. PMSi is also known to have a good compactness, magnetic field resistance and low cost. In our lab we are measuring the time resolution of two different models of PMS in order to build a fast radiation detector system

The interaction of hydrogen with metal alloys

Hydrogen diffusion coefficients were measured for several alloys, and these were determined to be about the same at 25 C for all alloys investigated. The relation of structure, both metallurgical and crystallographic, to the observed hydrogen distribution on charging was investigated, as well as the role of hydride formation in the hydrogen resistance of metal alloys. An attempt was made to correlate the structures and compositions of metal alloys as well as other parameters with the ratios of their notched tensile strengths in hydrogen to that in helium, R(H2/He), which are believed to represent a measure of their hydrogen resistance. Evidence supports the belief that hydrogen permeability and hydrogen resistance are increased by smaller grain sizes for a given alloy composition

Beyond the Plate: Leisure Studies as a Recipe for Food Justice

To address the issues that have been derived from the dominant forces in our food systems, movements such as food justice strive to find solutions through decolonization and addressing barriers to accessing healthy, affordable and culturally representative food. One group of individuals that are heavily involved in, and impacted by, food justice are college students. This study seeks to explore the extent to which college students’ involvement in food justice is shaped by their free time. With this research, I strive to bring in the voices of college students, while also bridging a gap in the field by bringing leisure studies, or free time, into the conversation with food justice. I distributed a survey to a group of students majoring in environmental science and studies, in addition to a range of other fields, to gain perspective on their perceptions on the intersection of free time and food justice, as well as meal-based discussion via a focus group. Through this, I found that college students are both in need of the work that food justice does, such as ensuring affordability, but they generally lack the resources or time to participate in the movement. However, it was also discovered that food justice looks different in each context, in terms of who is carrying out the work, as well as in the issues it is trying to solve; thus, there is ultimately not one way to use one’s free time to participate in it

Temperature dependent orbital degree of freedom in a bilayer manganite by magnetic Compton scattering

We have measured temperature-dependent magnetic Compton profiles (MCPs) from a single crystal of La$_{1.2}$Sr$_{1.8}$Mn$_2$O$_7$. The MCPs, which involved the scattering of circularly polarized x-rays, are in general related to the momentum density of all the unpaired spins in the system. Nevertheless, we show that when the x-ray scattering vector lies along the [110] direction, the number of magnetic electrons of a specific symmetry, i.e. $d$-electrons of $x^2-y^2$ symmetry, yield a distinct signature in the MCP, allowing us to monitor substantial changes in the occupancy of the $d_{x^2-y^2}$ states over the investigated temperature range of 5-200K. This study indicates that magnetic Compton scattering can provide a powerful window on the properties of specific magnetic electrons in complex materials.Comment: 5 pages, 4 figures, to appear in Phys. Rev. Let

On the nucleon self-energy in nuclear matter

We consider the nucleon self-energy in nuclear matter in the absence of Pauli blocking. It is evaluated using the partial-wave analysis of $NN$ scattering data. Our results are compared with that of a realistic calculation to estimate the effect of this blocking. It is also possible to use our results as a check on the realistic calculations.Comment: 6 pages, 2 figure

The Exonuclease Activity of hPMC2 is Required for Transcriptional Regulation of The QR Gene and Repair of Estrogen-Induced Abasic Sites

We have previously reported that the expression of antioxidative stress enzymes is upregulated by trans-hydroxytamoxifen (TOT) in breast epithelial cell lines providing protection against estrogen-induced DNA damage. This regulation involves Estrogen Receptor β (ERβ) recruitment to the Electrophile Response Element (EpRE) and a novel protein, human homolog of Xenopus gene which Prevents Mitotic Catastrophe (hPMC2). We have also demonstrated that ERβ and hPMC2 are required for TOT-dependent recruitment of poly (ADP-ribose) polymerase 1 (PARP-1) and Topoisomerase IIβ (Topo IIβ) to the EpRE. Sequence analysis reveals that the C-terminus of hPMC2 encodes a putative exonuclease domain. Using in vitro kinetic assays, we found that hPMC2 is a 3\u27-5\u27 non-processive exonuclease that degrades both single-stranded and double-stranded substrates. Mutation of two conserved carboxylate residues drastically reduced the exonuclease activity of hPMC2, indicating the relative importance of the catalytic residues. Western blot analysis of breast cancer cell lines for Quinone Reductase (QR) levels revealed that the intrinsic exonuclease activity of hPMC2 was required for TOT-induced QR upregulation. Chromatin immunoprecipitation (ChIP) assays also indicated that hPMC2 was involved in the formation of strand breaks observed with TOT treatment and is specific for the EpRE-containing region of the QR gene. We also determined that the transcription factor NF-E2-related factor-2 (Nrf2) is involved in the specificity of hPMC2 for the EpRE. In addition, we determined that the catalytic activity of hPMC2 is required for repair of abasic sites that result from estrogen-induced DNA damage. Thus, our study provides a mechanistic basis for transcriptional regulation by hPMC2 and provides novel insights into its role in cancer prevention