355 research outputs found

    CTCF loss has limited effects on global genome architecture in Drosophila despite critical regulatory functions.

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    Vertebrate genomes are partitioned into contact domains defined by enhanced internal contact frequency and formed by two principal mechanisms: compartmentalization of transcriptionally active and inactive domains, and stalling of chromosomal loop-extruding cohesin by CTCF bound at domain boundaries. While Drosophila has widespread contact domains and CTCF, it is currently unclear whether CTCF-dependent domains exist in flies. We genetically ablate CTCF in Drosophila and examine impacts on genome folding and transcriptional regulation in the central nervous system. We find that CTCF is required to form a small fraction of all domain boundaries, while critically controlling expression patterns of certain genes and supporting nervous system function. We also find that CTCF recruits the pervasive boundary-associated factor Cp190 to CTCF-occupied boundaries and co-regulates a subset of genes near boundaries together with Cp190. These results highlight a profound difference in CTCF-requirement for genome folding in flies and vertebrates, in which a large fraction of boundaries are CTCF-dependent and suggest that CTCF has played mutable roles in genome architecture and direct gene expression control during metazoan evolution

    Surface properties of glass micropipettes and their effect on biological studies

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    In this paper, an investigation on surface properties of glass micropipettes and their effect on biological applications is reported. Pipettes were pulled under different pulling conditions and the effect of each pulling parameter was analyzed. SEM stereoscopic technique was used to reveal the surface roughness properties of pipette tip and pipette inner wall in 3D. More than 20 pipettes were reconstructed. Pipette heads were split open using focused ion beam (FIB) milling for access to the inner walls. It is found that surface roughness parameters are strongly related on the tip size. Bigger pipettes have higher average surface roughness and lower developed interfacial area ratio. Furthermore, the autocorrelation of roughness model of the inner surface shows that the inner surface does not have any tendency of orientation and is not affected by pulling direction. To investigate the effect of surface roughness properties on biological applications, patch-clamping tests were carried out by conventional and FIB-polished pipettes. The results of the experiments show that polished pipettes make significantly better seals. The results of this work are of important reference value for achieving pipettes with desired surface properties and can be used to explain biological phenomenon such as giga-seal formation

    Auxiliary gauge mediation: a new route to mini-split supersymmetry

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    The discovery of a standard-model-like Higgs at 126 GeV and the absence of squark signals thus far at the LHC both point towards a mini-split spectrum for supersymmetry. Within standard paradigms, it is non-trivial to realize a mini-split spectrum with heavier sfermions but lighter gauginos while simultaneously generating Higgs sector soft terms of the correct magnitude, suggesting the need for new models of supersymmetry breaking and mediation. In this paper, we present a new approach to mini-split model building based on gauge mediation by “auxiliary groups”, which are the anomaly-free continuous symmetries of the standard model in the limit of vanishing Yukawa couplings. In addition to the well-known flavor SU(3) [subscript F] and baryon-minus-lepton U(1) [subscript B−L] groups, we find that an additional U(1) [subscript H] acting on the Higgs doublets alone can be used to generate Higgs soft masses and B-terms necessary for a complete model of mini-split. Auxiliary gauge mediation is a special case of Higgsed gauge mediation, and we review the resulting two-loop scalar soft terms as well as three-loop gaugino masses. Along the way, we present a complete two-loop calculation of A-terms and B-terms in gauge mediation, which — contrary to a common misconception — includes a non-zero contribution at the messenger threshold which can be sizable in models with light gauginos. We present several phenomenologically acceptable mini-split spectra arising from auxiliary gauge mediation and highlight a complete minimal model which realizes the required spectrum and Higgs sector soft terms with a single U(1) [subscript X] auxiliary gauge symmetry. We discuss possible experimental consequences.United States. Dept. of Energy (Cooperative Research Agreement DE-FG02-05ER-41360)National Science Foundation (U.S.). Graduate Research Fellowship ProgramSimons Foundation (Postdoctoral Fellowship)United States. Dept. of Energy (Early Career Research Program DE-FG02-11ER-41741

    Особливості формування самостійної пізнавальної діяльності майбутніх учителів математики

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    (uk) У статті зроблено спробу розкрити особливості самостійної пізнавальної діяльності майбутніх вчителів; досліджуються різні підходи до цього поняття; розкриваються такі його складові, як самостійність, пізнавальна самостійність, пізнавальна діяльність.(ru) В статье сделана попытка раскрыть особенности самостоятельной познавательной деятельности будущих учителей; исследуются различные подходы к этому понятию; раскрываются такие его составляющие, как самостоятельность, познавательная самостоятельность, познавательная деятельность

    Cinnamon extract induces tumor cell death through inhibition of NFκB and AP1

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    <p>Abstract</p> <p>Background</p> <p><it>Cinnamomum cassia </it>bark is the outer skin of an evergreen tall tree belonging to the family Lauraceae containing several active components such as essential oils (cinnamic aldehyde and cinnamyl aldehyde), tannin, mucus and carbohydrate. They have various biological functions including anti-oxidant, anti-microbial, anti-inflammation, anti-diabetic and anti-tumor activity. Previously, we have reported that anti-cancer effect of cinnamon extracts is associated with modulation of angiogenesis and effector function of CD8<sup>+ </sup>T cells. In this study, we further identified that anti-tumor effect of cinnamon extracts is also link with enhanced pro-apoptotic activity by inhibiting the activities NFκB and AP1 in mouse melanoma model.</p> <p>Methods</p> <p>Water soluble cinnamon extract was obtained and quality of cinnamon extract was evaluated by HPLC (High Performance Liquid Chromatography) analysis. In this study, we tested anti-tumor activity and elucidated action mechanism of cinnamon extract using various types of tumor cell lines including lymphoma, melanoma, cervix cancer and colorectal cancer <it>in vitro </it>and <it>in vivo </it>mouse melanoma model.</p> <p>Results</p> <p>Cinnamon extract strongly inhibited tumor cell proliferation <it>in vitro </it>and induced active cell death of tumor cells by up-regulating pro-apoptotic molecules while inhibiting NFκB and AP1 activity and their target genes such as <it>Bcl-2</it>, <it>BcL-xL </it>and <it>survivin</it>. Oral administration of cinnamon extract in melanoma transplantation model significantly inhibited tumor growth with the same mechanism of action observed <it>in vitro</it>.</p> <p>Conclusion</p> <p>Our study suggests that anti-tumor effect of cinnamon extracts is directly linked with enhanced pro-apoptotic activity and inhibition of NFκB and AP1 activities and their target genes <it>in vitro </it>and <it>in vivo </it>mouse melanoma model. Hence, further elucidation of active components of cinnamon extract could lead to development of potent anti-tumor agent or complementary and alternative medicine for the treatment of diverse cancers.</p

    Significant quantum effects in hydrogen activation

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    Dissociation of molecular hydrogen is an important step in a wide variety of chemical, biological, and physical processes. Due to the light mass of hydrogen, it is recognized that quantum effects are often important to its reactivity. However, understanding how quantum effects impact the reactivity of hydrogen is still in its infancy. Here, we examine this issue using a well-defined Pd/Cu(111) alloy that allows the activation of hydrogen and deuterium molecules to be examined at individual Pd atom surface sites over a wide range of temperatures. Experiments comparing the uptake of hydrogen and deuterium as a function of temperature reveal completely different behavior of the two species. The rate of hydrogen activation increases at lower sample temperature, whereas deuterium activation slows as the temperature is lowered. Density functional theory simulations in which quantum nuclear effects are accounted for reveal that tunneling through the dissociation barrier is prevalent for H2 up to ∼190 K and for D2 up to ∼140 K. Kinetic Monte Carlo simulations indicate that the effective barrier to H2 dissociation is so low that hydrogen uptake on the surface is limited merely by thermodynamics, whereas the D2 dissociation process is controlled by kinetics. These data illustrate the complexity and inherent quantum nature of this ubiquitous and seemingly simple chemical process. Examining these effects in other systems with a similar range of approaches may uncover temperature regimes where quantum effects can be harnessed, yielding greater control of bond-breaking processes at surfaces and uncovering useful chemistries such as selective bond activation or isotope separation

    Language in international business: a review and agenda for future research

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    A fast growing number of studies demonstrates that language diversity influences almost all management decisions in modern multinational corporations. Whereas no doubt remains about the practical importance of language, the empirical investigation and theoretical conceptualization of its complex and multifaceted effects still presents a substantial challenge. To summarize and evaluate the current state of the literature in a coherent picture informing future research, we systematically review 264 articles on language in international business. We scrutinize the geographic distributions of data, evaluate the field’s achievements to date in terms of theories and methodologies, and summarize core findings by individual, group, firm, and country levels of analysis. For each of these dimensions, we then put forward a future research agenda. We encourage scholars to transcend disciplinary boundaries and to draw on, integrate, and test a variety of theories from disciplines such as psychology, linguistics, and neuroscience to gain a more profound understanding of language in international business. We advocate more multi-level studies and cross-national research collaborations and suggest greater attention to potential new data sources and means of analysis

    Equilibrium with a Market of Permits

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