3,247 research outputs found
Eliminating Mitochondrial DNA from Sperm
Most eukaryotes show uniparental inheritance of mitochondrial DNA (mtDNA). In this issue of Developmental Cell, DeLuca and O'Farrell (2012) show that active elimination of mtDNA during sperm development in Drosophila ensures that mature spermatozoa are devoid of DNA
Ethical Implications in AI-Powered Trend Research Platforms
The manuscript discusses the limitations of applying AI in trend research platforms for the fashion system. This analysis intends to take a position within the emergent research topic of AI. Considering its ethical implications, we explore the opportunities of implementing AI to support trend research from a design-oriented perspective, realising the relationship between fashion and trends, which is central in shaping the future. Examples of AI-powered trend platforms evidence how valuable their insights are for strategic innovation. The analysis focuses on platforms that provide tailored services using AI and expert interpretation. Virtue ethics of technology serves as a useful framework to examine this topic, proposing a new set of virtues that respond to technology’s shaping of behaviour and its disadvantages. The risks of applying AI are many-fold; the consequences perpetuate power imbalances and social inequality. Proposing guidelines for enabling a responsible practice explores how to forge ethics into AI, creating a pluralised practice
Stabilizing Superconductivity in Nanowires by Coupling to Dissipative Environments
We present a theory for a finite-length superconducting nanowire coupled to
an environment. We show that in the absence of dissipation quantum phase slips
always destroy superconductivity, even at zero temperature. Dissipation
stabilizes the superconducting phase. We apply this theory to explain the
"anti-proximity effect" recently seen by Tian et. al. in Zinc nanowires.Comment: 4 pages, 3 figure
Supermassive black hole seeds from sub-keV dark matter
Quasars observed at redshifts are powered by supermassive black
holes which are too large to have grown from early stellar remnants without
efficient super-Eddington accretion. A proposal for alleviating this tension is
for dust and metal-free gas clouds to have undergone a process of direct
collapse, producing black hole seeds of mass
around redshift . For direct collapse to occur, a large flux of UV
photons must exist to photodissociate molecular hydrogen, allowing the gas to
cool slowly and avoid fragmentation. We investigate the possibility of sub-keV
mass dark matter decaying or annihilating to produce the UV flux needed to
cause direct collapse. We find that annihilating dark matter with a mass in the
range of can produce the
required flux while avoiding existing constraints. A non-thermally produced
dark matter particle which comprises the entire dark matter abundance requires
a thermally averaged cross section of
cms. Alternatively, the flux could originate from a thermal relic which
comprises only a fraction of the total dark matter density.
Decaying dark matter models which are unconstrained by independent
astrophysical observations are unable to sufficiently suppress molecular
hydrogen, except in gas clouds embedded in dark matter halos which are larger,
cuspier, or more concentrated than current simulations predict. Lastly, we
explore how our results could change with the inclusion of full
three-dimensional effects. Notably, we demonstrate that if the
self-shielding is less than the conservative estimate used in this work, the
range of both annihilating and decaying dark matter models which can cause
direct collapse is significantly increased.Comment: 24 pages, 9 figures. Updated to match published versio
The [4+2] cycloaddition of donor-acceptor cyclobutanes and nitrosoarenes.
The Yb(OTf)3 catalyzed [4+2] cycloaddition between donor-acceptor cyclobutanes and nitrosoarenes is disclosed. This method facilitates the synthesis of tetrahydro-1,2-oxazines in good to excellent yields as single diastereomers. Except for a few electron-deficient nitrosoarenes, excellent regioselectivity was observed throughout these studies
Fluxes, Gaugings and Gaugino Condensates
Based on the correspondence between the N = 1 superstring compactifications
with fluxes and the N = 4 gauged supergravities, we study effective N = 1
four-dimensional supergravity potentials arising from fluxes and gaugino
condensates in the framework of orbifold limits of (generalized) Calabi-Yau
compactifications. We give examples in heterotic and type II orientifolds in
which combined fluxes and condensates lead to vacua with small supersymmetry
breaking scale. We clarify the respective roles of fluxes and condensates in
supersymmetry breaking, and analyze the scaling properties of the gravitino
mass.Comment: 17 pages, C
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Influences on Affiliate HRM Systems in Japanese MNCs in Southeast Asia
Using data from 160 Asian affiliates of American and Japanese MNCs, this paper explores the determinants of whether MNCs transfer their parent company HRM systems overseas or adopt local practices. We find that demographic predictor variables which have often been found in previous studies to predict similarity are relatively unimportant while perceived HRM competence of the MNC is an important determinant of HRM transfer
A cyclopentadienyl functionalized silylene-a flexible ligand for Si- And C-coordination
The synthesis of a 1,2,3,4-tetramethylcyclopentadienyl (Cp) substituted four-membered N-heterocyclic silylene [{PhC(NtBu) }Si(CMeH)] is reported first. Then, selected reactions with transition metal and a calcium precursor are shown. The proton of the Cp-unit is labile. This results in two different reaction pathways: (1) deprotonation and (2) rearrangement reactions. Deprotonation was achieved by the reaction of [{PhC(NtBu) }Si(CMeH)] with suitable zinc precursors. Rearrangement to [{PhC(NtBu) }(CMe)SiH], featuring a formally tetravalent silicon RCSi(R′)-H unit, was observed when the proton of the Cp ring was shifted from the Cp-ring to the silylene in the presence of a Lewis acid. This allows for the coordination of the Cp-ring to a calcium compound. Furthermore, upon reaction with transition metal dimers [MCl(cod)] (M = Rh, Ir; cod = 1,5-cyclooctadiene) the proton stays at the Cp-ring and the silylene reacts as a sigma donor, which breaks the dimeric structure of the precursors
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