8,679 research outputs found

    Molecular cloning and characterization of multiple transcripts of the hamster ALG7 gene

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    Thesis (D.Sc.D.)--Boston University, Henry M. Goldman School of Graduate Dentistry, 1992 (Oral Biology).Includes bibliographical references (leaves 70-84).The ALG7 gene encodes the tunicamycin-sensitive, dolichol-P-dependent Nacetylglucosamine- 1-phosphate transferase, GPT, that catalyzes the synthesis of the first dolichollinked sugar, Dol-PP-GlcNAc, in the N-glycosylation pathway. ALG7 has been evQlutionarily conserved and is essential for growth in all eukaryotes. The ALG7 gene expression in yeast is known to be regulated in part by the 3' untranslated regions (UTR) of the ALG7 multiple transcripts at the posttranscriptional level. To examine the regulatory features of the mammalian ALG7 gene, cloning and characterization of the hamster ALG7 mRNAs were undertaken. Polymerase chain reaction (PCR) using a single ALG7 gene-specific primer was performed to clone the cDNAs corresponding to the 3' and 5' ends of the ALG7 mRNAs from the Chinese hamster ovary (CHO) cells. The initial Northern blot analysis using a hamster ALG7 genomic DNA as a probe has shown that in the CHO cells the ALG7 gene is transcribed into three major messages, approximately 1.5, 1.9, and 2.2 kb in size. The 1.9 kb transcripts were cloned and sequenced. There is one consensus polyadenylation signal AAUAAA located 12 nucleotides (nt) upstream to the major poly(A) site. Three additional minor poly(A) sites are located at 18, 21 and 29 nt downstream from the AAUAAA sequence in this 1.9 kb class of mRNAs. [TRUNCATED

    Hotspots of dendritic spine turnover facilitate clustered spine addition and learning and memory.

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    Modeling studies suggest that clustered structural plasticity of dendritic spines is an efficient mechanism of information storage in cortical circuits. However, why new clustered spines occur in specific locations and how their formation relates to learning and memory (L&M) remain unclear. Using in vivo two-photon microscopy, we track spine dynamics in retrosplenial cortex before, during, and after two forms of episodic-like learning and find that spine turnover before learning predicts future L&M performance, as well as the localization and rates of spine clustering. Consistent with the idea that these measures are causally related, a genetic manipulation that enhances spine turnover also enhances both L&M and spine clustering. Biophysically inspired modeling suggests turnover increases clustering, network sparsity, and memory capacity. These results support a hotspot model where spine turnover is the driver for localization of clustered spine formation, which serves to modulate network function, thus influencing storage capacity and L&M

    Loma Linda University Dentistry - Volume 25, Number 2

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    Contents: 8-10 | New Positions Filled: Burdick, Li, Sherwin14 | Alumni Student Convention Class of \u276418 | Factors Affecting Pulp Regeneration30 | Student Research Winners34 | Commencement 2014: You Make Us Look Good 46 | Omni Dean49 | Marathon Manhttps://scholarsrepository.llu.edu/articulator/1007/thumbnail.jp

    A scaling law for distinct electrocaloric cooling performance in low-dimensional organic, relaxor and anti-ferroelectrics

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    Electrocaloric (EC) materials show promise in eco-friendly solid-state refrigeration and integrable on-chip thermal management. While direct measurement of EC thin-films still remains challenging, a generic theoretical framework for quantifying the cooling properties of rich EC materials including normal-, relaxor-, organic- and anti-ferroelectrics is imperative for exploiting new flexible and room-temperature cooling alternatives. Here, we present a versatile theory that combines Master equation with Maxwell relations and analytically relates the macroscopic cooling responses in EC materials with the intrinsic diffuseness of phase transitions and correlation characteristics. Under increased electric fields, both EC entropy and adiabatic temperature changes increase quadratically initially, followed by further linear growth and eventual gradual saturation. The upper bound of entropy change (∆Smax) is limited by distinct correlation volumes (V cr ) and transition diffuseness. The linearity between V cr and the transition diffuseness is emphasized, while ∆Smax = 300 kJ/(K.m3) is obtained for Pb0.8Ba0.2ZrO3. The ∆Smax in antiferroelectric Pb0.95Zr0.05TiO3, Pb0.8Ba0.2ZrO3 and polymeric ferroelectrics scales proportionally with V cr −2.2, owing to the one-dimensional structural constraint on lattice-scale depolarization dynamics; whereas ∆Smax in relaxor and normal ferroelectrics scales as ∆Smax ~ V cr −0.37, which tallies with a dipolar interaction exponent of 2/3 in EC materials and the well-proven fractional dimensionality of 2.5 for ferroelectric domain walls

    Mass dependence of light nucleus production in ultrarelativistic heavy ion collisions

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    Light nuclei can be produced in the central reaction zone via coalescence in relativistic heavy ion collisions. E864 at BNL has measured the production of ten light nuclei with nuclear number of A=1 to A=7 at rapidity y1.9y\simeq1.9 and pT/A300MeV/cp_{T}/A\leq300MeV/c. Data were taken with a Au beam of momentum of 11.5 A GeV/cGeV/c on a Pb or Pt target with different experimental settings. The invariant yields show a striking exponential dependence on nuclear number with a penalty factor of about 50 per additional nucleon. Detailed analysis reveals that the production may depend on the spin factor of the nucleus and the nuclear binding energy as well.Comment: (6 pages, 3 figures), some changes on text, references and figures' lettering. To be published in PRL (13Dec1999

    Antideuteron yield at the AGS and coalescence implications

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    We present Experiment 864's measurement of invariant antideuteron yields in 11.5A GeV/c Au + Pt collisions. The analysis includes 250 million triggers representing 14 billion 10% central interactions sampled for events with high mass candidates. We find (1/2 pi pt) d^(2)N/dydpt = 3.5 +/- 1.5 (stat.) +0.9,-0.5 (sys.) x 10^(-8) GeV^(-2)c^(2) for 1.8=0.35 GeV/c (y(cm)=1.6) and 3.7 +/- 2.7 (stat.) +1.4,-1.5 (sys.) x 10^(-8) GeV^(-2)c^(2) for 1.4=0.26 GeV/c, and a coalescence parameter B2-bar of 4.1 +/- 2.9 (stat.) +2.3,-2.4 (sys.) x 10^(-3) GeV^(2)c^(-3). Implications for the coalescence model and antimatter annihilation are discussed.Comment: 8 pages, 4 figures, Latex, submitted to Phys. Rev. Let

    Performance and on-sky optical characterization of the SPTpol instrument

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    In January 2012, the 10m South Pole Telescope (SPT) was equipped with a polarization-sensitive camera, SPTpol, in order to measure the polarization anisotropy of the cosmic microwave background (CMB). Measurements of the polarization of the CMB at small angular scales (~several arcminutes) can detect the gravitational lensing of the CMB by large scale structure and constrain the sum of the neutrino masses. At large angular scales (~few degrees) CMB measurements can constrain the energy scale of Inflation. SPTpol is a two-color mm-wave camera that consists of 180 polarimeters at 90 GHz and 588 polarimeters at 150 GHz, with each polarimeter consisting of a dual transition edge sensor (TES) bolometers. The full complement of 150 GHz detectors consists of 7 arrays of 84 ortho-mode transducers (OMTs) that are stripline coupled to two TES detectors per OMT, developed by the TRUCE collaboration and fabricated at NIST. Each 90 GHz pixel consists of two antenna-coupled absorbers coupled to two TES detectors, developed with Argonne National Labs. The 1536 total detectors are read out with digital frequency-domain multiplexing (DfMUX). The SPTpol deployment represents the first on-sky tests of both of these detector technologies, and is one of the first deployed instruments using DfMUX readout technology. We present the details of the design, commissioning, deployment, on-sky optical characterization and detector performance of the complete SPTpol focal plane.Comment: 15 pages, 6 figures. Conference: SPIE Astronomical Telescopes and Instrumentation 201

    Spitzer view on the evolution of star-forming galaxies from z=0 to z~3

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    We use a 24 micron selected sample containing more than 8,000 sources to study the evolution of star-forming galaxies in the redshift range from z=0 to z~3. We obtain photometric redshifts for most of the sources in our survey using a method based on empirically-built templates spanning from ultraviolet to mid-infrared wavelengths. The accuracy of these redshifts is better than 10% for 80% of the sample. The derived redshift distribution of the sources detected by our survey peaks at around z=0.6-1.0 (the location of the peak being affected by cosmic variance), and decays monotonically from z~1 to z~3. We have fitted infrared luminosity functions in several redshift bins in the range 0<z<~3. Our results constrain the density and/or luminosity evolution of infrared-bright star-forming galaxies. The typical infrared luminosity (L*) decreases by an order of magnitude from z~2 to the present. The cosmic star formation rate (SFR) density goes as (1+z)^{4.0\pm0.2} from z=0 to z=0.8. From z=0.8 to z~1.2, the SFR density continues rising with a smaller slope. At 1.2<z<3, the cosmic SFR density remains roughly constant. The SFR density is dominated at low redshift (z<0.5) by galaxies which are not very luminous in the infrared (L_TIR<1.e11 L_sun, where L_TIR is the total infrared luminosity, integrated from 8 to 1000 micron). The contribution from luminous and ultraluminous infrared galaxies (L_TIR>1.e11 L_sun) to the total SFR density increases steadily from z~0 up to z~2.5, forming at least half of the newly-born stars by z~1.5. Ultraluminous infrared galaxies (L_TIR>1.e12 L_sun) play a rapidly increasing role for z>~1.3.Comment: 28 pages, 17 figures, accepted for publication in Ap
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