Automatic Design of Efficient Application-centric Architectures.

As the market for embedded devices continues to grow, the demand for high performance, low cost, and low power computation grows as well. Many embedded applications perform computationally intensive tasks such as processing streaming video or audio, wireless communication, or speech recognition and must be implemented within tight power budgets. Typically, general purpose processors are not able to meet these performance and power requirements. Custom hardware in the form of loop accelerators are often used to execute the compute-intensive portions of these applications because they can achieve significantly higher levels of performance and power efficiency. Automated hardware synthesis from high level specifications is a key technology used in designing these accelerators, because the resulting hardware is correct by construction, easing verification and greatly decreasing time-to-market in the quickly evolving embedded domain. In this dissertation, a compiler-directed approach is used to design a loop accelerator from a C specification and a throughput requirement. The compiler analyzes the loop and generates a virtual architecture containing sufficient resources to sustain the required throughput. Next, a software pipelining scheduler maps the operations in the loop to the virtual architecture. Finally, the accelerator datapath is derived from the resulting schedule. In this dissertation, synthesis of different types of loop accelerators is investigated. First, the system for synthesizing single loop accelerators is detailed. In particular, a scheduler is presented that is aware of the effects of its decisions on the resulting hardware, and attempts to minimize hardware cost. Second, synthesis of multifunction loop accelerators, or accelerators capable of executing multiple loops, is presented. Such accelerators exploit coarse-grained hardware sharing across loops in order to reduce overall cost. Finally, synthesis of post-programmable accelerators is presented, allowing changes to be made to the software after an accelerator has been created. The tradeoffs between the flexibility, cost, and energy efficiency of these different types of accelerators are investigated. Automatically synthesized loop accelerators are capable of achieving order-of-magnitude gains in performance, area efficiency, and power efficiency over processors, and programmable accelerators allow software changes while maintaining highly efficient levels of computation.Ph.D.Computer Science & EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/61644/1/fank_1.pd

Nano-Size Layered Manganese-Calcium Oxide as an Efficient and Biomimetic Catalyst for Water Oxidation Under Acidic Conditions: Comparable To Platinum

Inspired by Nature's catalyst, a nano-size layered manganese-calcium oxide showed a low overvoltage for water oxidation in acidic solutions, which is comparable to platinum.Institute for Advanced Studies in Basic Sciences and the National Elite FoundationUS Department of Energy, Office of Basic Energy Sciences, Division of Chemical, Geochemical and Biological Sciences DE-FG02-86ER13622, DE-FG0209ER16119Russian Foundation for Basic Research 11-04-01389a, 12-0492101a, 13-04-92711aMolecular and Cell Biology Programs of the Russian Academy of SciencesCenter for Electrochemistr

Time-Dependent c-Myc Transactomes Mapped by Array-Based Nuclear Run-On Reveal Transcriptional Modules in Human B Cells

The definition of transcriptional networks through measurements of changes in gene expression profiles and mapping of transcription factor binding sites is limited by the moderate overlap between binding and gene expression changes and the inability to directly measure global nuclear transcription (coined "transactome").We developed a method to measure nascent nuclear gene transcription with an Array-based Nuclear Run-On (ANRO) assay using commercial microarray platforms. This strategy provides the missing component, the transactome, to fully map transcriptional networks. ANRO measurements in an inducible c-Myc expressing human P493-6 B cell model reveals time-dependent waves of transcription, with a transactome early after c-Myc induction that does not persist at a late, steady-state phase, when genes that are regulated by c-Myc and E2F predominate. Gene set matrix analysis further uncovers functionally related groups of genes putatively regulated by waves of transcription factor motifs following Myc induction, starting with AP1 and CREB that are followed by EGR1, NFkB and STAT, and ending with E2F, Myc and ARNT/HIF motifs.By coupling ANRO with previous global mapping of c-Myc binding sites by chromatin immunoprecipitation (ChIP) in P493-6 cells, we define a set of transcriptionally regulated direct c-Myc target genes and pave the way for the use of ANRO to comprehensively map any transcriptional network

Helicity-Selective Enhancement and Polarization Control of Attosecond High Harmonic Waveforms Driven by Bichromatic Circularly Polarized Laser Fields

source of bright, circularly polarized, extreme ultraviolet, and soft x-ray beams, where the individual harmonics themselves are completely circularly polarized. Here, we demonstrate the ability to preferentially select either the right or left circularly polarized harmonics simply by adjusting the relative intensity ratio of the bichromatic circularly polarized driving laser field. In the frequency domain, this significantly enhances the harmonic orders that rotate in the same direction as the higher-intensity driving laser. In the time domain, this helicity-dependent enhancement corresponds to control over the polarization of the resulting attosecond waveforms. This helicity control enables the generation of circularly polarized high harmonics with a user-defined polarization of the underlying attosecond bursts. In the future, this technique should allow for the production of bright highly elliptical harmonic supercontinua as well as the generation of isolated elliptically polarized attosecond pulses.H. K. and M. M. graciously acknowledge support from the Department of Energy BES Award No. DE-FG02- 99ER14982 for the experimental implementation, as well as a MURI grant from the Air Force Office of Scientific Research under Award No. FA9550-16-1-0121 for the theory. J. E. and C. M. acknowledge support from National Science Foundation Graduate Research Fellowships (Grant No. DGE-1144083). C. H.-G. acknowl- edges support from the Marie Curie International Outgoing Fellowship within the EU Seventh Framework Programme for Research and Technological Development (2007-2013), under REA Grant No. 328334, from Junta de Castilla y León (Project No. SA046U16) and Spanish Ministerio de Economía y Competitividad, MINECO (Projects No. FIS2013-44174-P and No. FIS2016-75652-P). Part of this work utilized the Janus supercomputer, which is sup- ported by the U.S. National Science Foundation (Grant No. CNS-0821794) and the University of Colorado Boulder

IR and UV Galaxies at z=0.6 -- Evolution of Dust Attenuation and Stellar Mass as Revealed by SWIRE and GALEX

We study dust attenuation and stellar mass of $\rm z\sim 0.6$ star-forming galaxies using new SWIRE observations in IR and GALEX observations in UV. Two samples are selected from the SWIRE and GALEX source catalogs in the SWIRE/GALEX field ELAIS-N1-00 ($\Omega = 0.8$ deg$^2$). The UV selected sample has 600 galaxies with photometric redshift (hereafter photo-z) $0.5 \leq z \leq 0.7$ and NUV$\leq 23.5$ (corresponding to \rm L_{FUV} \geq 10^{9.6} L_\sun). The IR selected sample contains 430 galaxies with $f_{24\mu m} \geq 0.2$ mJy (\rm L_{dust} \geq 10^{10.8} L_\sun) in the same photo-z range. It is found that the mean $\rm L_{dust}/L_{FUV}$ ratios of the z=0.6 UV galaxies are consistent with that of their z=0 counterparts of the same $\rm L_{FUV}$. For IR galaxies, the mean $\rm L_{dust}/L_{FUV}$ ratios of the z=0.6 LIRGs (\rm L_{dust} \sim 10^{11} L_\sun) are about a factor of 2 lower than local LIRGs, whereas z=0.6 ULIRGs (\rm L_{dust} \sim 10^{12} L_\sun) have the same mean $\rm L_{dust}/L_{FUV}$ ratios as their local counterparts. This is consistent with the hypothesis that the dominant component of LIRG population has changed from large, gas rich spirals at z$>0.5$ to major-mergers at z=0. The stellar mass of z=0.6 UV galaxies of \rm L_{FUV} \leq 10^{10.2} L_\sun is about a factor 2 less than their local counterparts of the same luminosity, indicating growth of these galaxies. The mass of z=0.6 UV lunmous galaxies (UVLGs: \rm L_{FUV} > 10^{10.2} L_\sun) and IR selected galaxies, which are nearly exclusively LIRGs and ULIRGs, is the same as their local counterparts.Comment: 27 pages, 8 figures, to be published in the Astrophysical Journal Supplement series dedicated to GALEX result

Bright, single helicity, high harmonics driven by mid-infrared bicircular laser fields

[EN]High-harmonic generation (HHG) is a unique tabletop light source with femtosecond-to-attosecond pulse duration and tailorable polarization and beam shape. Here, we use counter-rotating femtosecond laser pulses of 0.8 µm and 2.0 μm to extend the photon energy range of circularly polarized high-harmonics and also generate single-helicity HHG spectra. By driving HHG in helium, we produce circularly polarized soft x-ray harmonics beyond 170 eV—the highest photon energy of circularly polarized HHG achieved to date. In an Ar medium, dense spectra at photon energies well beyond the Cooper minimum are generated, with regions composed of a single helicity—consistent with the generation of a train of circularly polarized attosecond pulses. Finally, we show theoretically that circularly polarized HHG photon energies can extend beyond the carbon K edge, extending the range of molecular and materials systems that can be accessed using dynamic HHG chiral spectro-microscopiesDepartment of Energy BES (DE-FG02-99ER14982); Air Force Office of Scientific Research (FA9550-16-1-0121); National Science Foundation (DGE-1144083, DGE-1650115); European Research Council (8511201); Ministerio de Ciencia, Innovación y Universidades (PID2019-106910GB-100); Junta de Castilla y León (SA287P18); Ramón y Cajal contract (RYC-2017-22745)

The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125

We report on multi-wavelength observations, ranging from the X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O I, Si II, and C IV, implying a likely redshift of z = 1.547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of ~7.0 degrees, and implying an intrinsic GRB energy in the 1 - 10,000 keV band of around E = (6.3 - 6.9)x 10^(51) erg (based on the fluences measured by the gamma-ray detectors of the IPN network). GRB 070125 is among the brightest afterglows observed to date. The spectral energy distribution implies a host extinction of Av < 0.9 mag. Two rebrightening episodes are observed, one with excellent time coverage, showing an increase in flux of 56% in ~8000 seconds. The evolution of the afterglow light curve is achromatic at all times. Late-time observations of the afterglow do not show evidence for emission from an underlying host galaxy or supernova. Any host galaxy would be subluminous, consistent with current GRB host-galaxy samples. Evidence for strong Mg II absorption features is not found, which is perhaps surprising in view of the relatively high redshift of this burst and the high likelihood for such features along GRB-selected lines of sight.Comment: 50 pages, 9 figures, 5 tables Accepted to the Astrophysical Journa

Phase matching of noncollinear sum and difference frequency high harmonic generation above and below the critical ionization level

We investigate the macroscopic physics of noncollinear high harmonic generation (HHG) at high pressures. We make the first experimental demonstration of phase matching of noncollinear high-order-difference-frequency generation at ionization fractions above the critical ionization level, which normally sets an upper limit on the achievable cutoff photon energies. Additionally, we show that noncollinear high-order-sum-frequency generation requires much higher pressures for phase matching than single-beam HHG does, which mitigates the short interaction region in this geometry. We also dramatically increase the experimentally realized cutoff energy of noncollinear circularly polarized HHG, reaching photon energies of 90 eV. Finally, we achieve complete angular separation of high harmonic orders without the use of a spectrometer.Department of Energy BES Award DE-FG02-99ER14982. MURI grant from the Air Force Office of Scientific Research under Award Number FA9550-16-1-0121. National Science Foundation Graduate Research Fellowship (DGE-1144083). Junta de Castilla y León (Project SA046U16) and Spanish MINECO (FIS2013-44174-P, FIS2016-75652-P)