Focal Plate Structure Alignment of the Dark Energy Spectroscopic Instrument

The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the universe using the Baryon Acoustic Oscillation (BAO) technique. The spectra of 35 million galaxies and quasars over $14000 \,\text{deg}^2$ will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 robotically positioned optic fibres. The fibres in turn feed ten broadband spectrographs. Proper alignment of focal plate structure, mainly consisting of a focal plate ring (FPR) and ten focal plate petals (FPP), is crucial in ensuring minimal loss of light in the focal plane. A coordinate measurement machine (CMM) metrology-based approach to alignment requires comprehensive characterisation of critical dimensions of the petals and the ring, all of which were 100% inspected. The metrology data not only served for quality assurance (QA), but also, with careful modelling of geometric transformations, informed the initial choice of integration accessories such as gauge blocks, pads, and shims. The integrated focal plate structure was inspected again on a CMM, and each petal was adjusted according to the updated focal plate metrology data until all datums were extremely close to nominal positions and optical throughput nearly reached the theoretically best possible value. This paper presents our metrology and alignment methodology and complete results for twelve official DESI petals. The as-aligned, total RMS optical throughput for 6168 positioner holes of twelve production petals was indirectly measured to be $99.88 \pm 0.12 \%$, well above the 99.5% project requirement. The successful alignment fully demonstrated the wealth of data, reproducibility, and micron-level precision made available by our CMM metrology-based approach.Comment: 17 pages, 10 figures, 3 table

On Various Ways of Measuring Unemployment, with Applications to Switzerland

This paper discusses first various ways of measuring unemployment and, borrowing ideas from the poverty measurement literature, proposes four more general unemployment indices which are parallel to Sen poverty index, to its generalization by Shorrocks, to the FGT, and to the Watts poverty indices. It then presents an empirical illustration based on Swiss data at the level of the “canton.” More precisely, using the so-called Shapley decomposition, it computes the contribution to the difference between the value of each of these four unemployment indices in a given “canton” and in Switzerland as a whole, of three components measuring, respectively, the impact of differences in the traditional unemployment rate, in the average unemployment duration, and in the inequality in the unemployment durations. The paper ends by discussing the impact on the results obtained of assumptions made concerning the maximum unemployment duration

Overview of the Dark Energy Spectroscopic Instrument

The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe using the Baryon Acoustic Oscillation technique. The spectra of 35 million galaxies and quasars over 14000 square degrees will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We present an overview of the instrumentation, the main technical requirements and challenges, and the current status of the project.Comment: 11 pages, 4 figure

MicroRNA and Target Protein Patterns Reveal Physiopathological Features of Glioma Subtypes

Gliomas such as oligodendrogliomas (ODG) and glioblastomas (GBM) are brain tumours with different clinical outcomes. Histology-based classification of these tumour types is often difficult. Therefore the first aim of this study was to gain microRNA data that can be used as reliable signatures of oligodendrogliomas and glioblastomas. We investigated the levels of 282 microRNAs using membrane-array hybridisation and real-time PCR in ODG, GBM and control brain tissues. In comparison to these control tissues, 26 deregulated microRNAs were identified in tumours and the tissue levels of seven microRNAs (miR-21, miR-128, miR-132, miR-134, miR-155, miR-210 and miR-409-5p) appropriately discriminated oligodendrogliomas from glioblastomas. Genomic, epigenomic and host gene expression studies were conducted to investigate the mechanisms involved in these deregulations. Another aim of this study was to better understand glioma physiopathology looking for targets of deregulated microRNAs. We discovered that some targets of these microRNAs such as STAT3, PTBP1 or SIRT1 are differentially expressed in gliomas consistent with deregulation of microRNA expression. Moreover, MDH1, the target of several deregulated microRNAs, is repressed in glioblastomas, making an intramitochondrial-NAD reduction mediated by the mitochondrial aspartate-malate shuttle unlikely. Understanding the connections between microRNAs and bioenergetic pathways in gliomas may lead to identification of novel therapeutic targets

A Spectroscopic Road Map for Cosmic Frontier: DESI, DESI-II, Stage-5

In this white paper, we present an experimental road map for spectroscopic experiments beyond DESI. DESI will be a transformative cosmological survey in the 2020s, mapping 40 million galaxies and quasars and capturing a significant fraction of the available linear modes up to z=1.2. DESI-II will pilot observations of galaxies both at much higher densities and extending to higher redshifts. A Stage-5 experiment would build out those high-density and high-redshift observations, mapping hundreds of millions of stars and galaxies in three dimensions, to address the problems of inflation, dark energy, light relativistic species, and dark matter. These spectroscopic data will also complement the next generation of weak lensing, line intensity mapping and CMB experiments and allow them to reach their full potential.Comment: Contribution to Snowmass 202

Bostonia: v. 61, no. 1-2, 4

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Astro2020 APC White Paper: The MegaMapper: a z > 2 spectroscopic instrument for the study of Inflation and Dark Energy

MegaMapper is a proposed ground-based experiment to measure Inflation parameters and Dark Energy from galaxy redshifts at

Banking and Financial Crises in United States History: What Guidance can History Offer Policymakers?

This paper assesses the validity of comparisons of the current financial crisis with past crises in the United States. We highlight aspects of two National Banking Era crises (the Panic of 1873 and the Panic of 1907) that are relevant for comparison with the Panic of 2008. In 1873, overinvestment in railroad debt and the default of railroad companies on that debt led to the failure of numerous brokerage houses, an antecedent to the modern investment bank. For the Panic of 1907, panic-related deposit withdrawals centered on the less regulated trust companies, which were less directly linked to the existing lender of last resort, similar to investment banks in 2008. The popular press has made numerous references to the banking crises (there were three main ones) of the Great Depression as relevant comparisons to the present crisis. This paper argues that such an analogy is inaccurate in general