316 research outputs found

    Caperton\u27s Next Generation: Beyond the Bank

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    The article looks at a panel discussion on judicial responsibility and the U.S. Supreme Court\u27s decision in \u27Caperton v. A.T. Massey Coal Co.\u27 discussed by several law professionals including Jed Shugerman, Debra Lyn Bassett and Dmitry Bam at a 2014 symposium held in the New York University

    Momentum-space entanglement after a quench in one-dimensional disordered fermionic systems

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    We numerically investigate the momentum-space entanglement entropy and entanglement spectrum of the random-dimer model and its generalizations, which circumvent Anderson localization, after a quench in the Hamiltonian parameters. The type of dynamics that occurs depends on whether or not the Fermi level of the initial state is near the energy of the delocalized states present in these models. If the Fermi level of the initial state is near the energy of the delocalized states, we observe an interesting slow logarithmic-like growth of the momentum-space entanglement entropy followed by an eventual saturation. Otherwise, the momentum-space entanglement entropy is found to rapidly saturate. We also find that the momentum-space entanglement spectrum reveals the presence of delocalized states in these models for long times after the quench and the many-body entanglement gap decays logarithmically in time when the Fermi level is near the energy of the delocalized states.Comment: 4+e pages, 3 figure

    Infrared Galaxies in the Field of the Massive Cluster Abell S1063: Discovery of a Luminous Kiloparsec-Sized HII Region in a Gravitationally Lensed IR-Luminous Galaxy at z=0.6z=0.6

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    Using the Spitzer Space Telescope and Herschel Space Observatory, we have conducted a survey of infrared galaxies in the field of the galaxy cluster Abell S1063 (AS1063) at z=0.347z=0.347, which is one of the most massive clusters known and a target of the HST CLASH and Frontier-Field surveys. The Spitzer/MIPS 24 ÎŒ\mum and Herschel/PACS & SPIRE images revealed that the core of AS1063 is surprisingly devoid of infrared sources, showing only a few detectable sources within the central r∌1â€Č\sim1^{\prime}. There is, however, one particularly bright source (2.3 mJy at 24 ÎŒ\mum; 106 mJy at 160 ÎŒ\mum), which corresponds to a background galaxy at z=0.61z=0.61. The modest magnification factor (4.0×\times) implies that this galaxy is intrinsically IR-luminous (LIR=3.1×1011 L⊙_{\rm IR}=3.1\times10^{11}\ \rm L_{\odot}). What is particularly interesting about this galaxy is that HST optical/near-infrared images show a remarkably bright and large (1 kpc) clump at one edge of the disk. Our follow-up optical/near-infrared spectroscopy shows Balmer (Hα\alpha-H8) and forbidden emission from this clump ([OII] λ\lambda3727, [OIII] λλ\lambda\lambda4959,5007, [NII] λλ\lambda\lambda6548,6583), indicating that it is a HII region. The HII region appears to have formed in-situ, as kinematically it is part of a rotating disk, and there is no evidence of nearby interacting galaxies. With an extinction correction of AV=1.5_{\rm V}=1.5 mag, the star formation rate of this giant HII region is ∌\sim10 M⊙_{\odot} yr−1^{-1}, which is exceptionally large, even for high redshift HII regions. Such a large and luminous HII region is often seen at z∌2z\sim2 but quite rare in the nearby Universe.Comment: Accepted for publication in the Astrophysical Journal. 29 pages, 15 figure

    Temporal dynamics of Prochlorococcus ecotypes in the Atlantic and Pacific oceans

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    To better understand the temporal and spatial dynamics of Prochlorococcus populations, and how these populations co-vary with the physical environment, we followed monthly changes in the abundance of five ecotypes—two high-light adapted and three low-light adapted—over a 5-year period in coordination with the Bermuda Atlantic Time Series (BATS) and Hawaii Ocean Time-series (HOT) programs. Ecotype abundance displayed weak seasonal fluctuations at HOT and strong seasonal fluctuations at BATS. Furthermore, stable ‘layered’ depth distributions, where different Prochlorococcus ecotypes reached maximum abundance at different depths, were maintained consistently for 5 years at HOT. Layered distributions were also observed at BATS, although winter deep mixing events disrupted these patterns each year and produced large variations in ecotype abundance. Interestingly, the layered ecotype distributions were regularly reestablished each year after deep mixing subsided at BATS. In addition, Prochlorococcus ecotypes each responded differently to the strong seasonal changes in light, temperature and mixing at BATS, resulting in a reproducible annual succession of ecotype blooms. Patterns of ecotype abundance, in combination with physiological assays of cultured isolates, confirmed that the low-light adapted eNATL could be distinguished from other low-light adapted ecotypes based on its ability to withstand temporary exposure to high-intensity light, a characteristic stress of the surface mixed layer. Finally, total Prochlorococcus and Synechococcus dynamics were compared with similar time series data collected a decade earlier at each location. The two data sets were remarkably similar—testimony to the resilience of these complex dynamic systems on decadal time scales.National Science Foundation (U.S.)Gordon and Betty Moore Foundatio

    Intraflagellar transporter protein (IFT27), an IFT25 binding partner, is essential for male fertility and spermiogenesis in mice

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    Intraflagellar transport (IFT) is an evolutionarily conserved mechanism essential for the assembly and maintenance of most eukaryotic cilia and flagella. In mice, mutations in IFT proteins have been shown to cause several ciliopathies including retinal degeneration, polycystic kidney disease, and hearing loss. However, little is known about its role in the formation of the sperm tail, which has the longest flagella of mammalian cells. IFT27 is a component of IFT-B complex and binds to IFT25 directly. In mice, IFT27 is highly expressed in the testis. To investigate the role of IFT27 in male germ cells, the floxed Ift27 mice were bred with Stra8-iCre mice so that the Ift27 gene was disrupted in spermatocytes/spermatids. The Ift27: Stra8-iCre mutant mice did not show any gross abnormalities, and all of the mutant mice survived to adulthood. There was no difference between testis weight/body weight between controls and mutant mice. All adult homozygous mutant males examined were completely infertile. Histological examination of the testes revealed abnormally developed germ cells during the spermiogenesis phase. The epididymides contained round bodies of cytoplasm. Sperm number was significantly reduced compared to the controls and only about 2% of them remained significantly reduced motility. Examination of epididymal sperm by light microscopy and SEM revealed multiple morphological abnormalities including round heads, short and bent tails, abnormal thickness of sperm tails in some areas, and swollen tail tips in some sperm. TEM examination of epididymal sperm showed that most sperm lost the 9+2\u27\u27 axoneme structure, and the mitochondria sheath, fibrous sheath, and outer dense fibers were also disorganized. Some sperm flagella also lost cell membrane. Levels of IFT25 and IFT81 were significantly reduced in the testis of the conditional Ift27 knockout mice, and levels of IFT20, IFT74, and IFT140 were not changed. Sperm lipid rafts, which were disrupted in the conditional Ift25 knockout mice, appeared to be normal in the conditional Ift27 knockout mice. Our findings suggest that like IFT25, IFT27, even though not required for ciliogenesis in somatic cells, is essential for sperm flagella formation, sperm function, and male fertility in mice. IFT25 and IFT27 control sperm formation/function through many common mechanisms, but IFT25 has additional roles beyond IFT27
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