1,427 research outputs found
Factors identification on optimization of ball placement tool for flip-chip- ball-grid-array product
Market demand on system-on-chip (SoC) using ball-attach technologies, it is time for ball-attach module to have an improvement on their capabilities within limited resources (man and machine). This paper identifies caused of factor which contributes more time to production time. Justification on improving ball-attach module cycle time during high volume activities is explained
Applications of the Ashtekar gravity to four dimensional hyperk\"ahler geometry and Yang-Mills Instantons
The Ashtekar-Mason-Newman equations are used to construct the hyperk\"ahler
metrics on four dimensional manifolds. These equations are closely related to
anti self-dual Yang-Mills equations of the infinite dimensional gauge Lie
algebras of all volume preserving vector fields. Several examples of
hyperk\"ahler metrics are presented through the reductions of anti self-dual
connections. For any gauge group anti self-dual connections on hyperk\"ahler
manifolds are constructed using the solutions of both Nahm and Laplace
equations.Comment: 9pages, Figures are not include
Ab initio calculations of neutrinoless decay refine neutrino mass limits
Neutrinos are perhaps the most elusive known particles in the universe. We
know they have some nonzero mass, but unlike all other particles, the absolute
scale remains unknown. In addition, their fundamental nature is uncertain; they
can either be their own antiparticles or exist as distinct neutrinos and
antineutrinos. The observation of the hypothetical process of neutrinoless
double-beta () decay would at once resolve both questions,
while providing a strong lead in understanding the abundance of matter over
antimatter in our universe. In the scenario of light-neutrino exchange, the
decay rate is governed by, and thereby linked to the effective mass of the
neutrino via, the theoretical nuclear matrix element (NME). In order to extract
the neutrino mass, if a discovery is made, or to assess the discovery potential
of next-generation searches, it is essential to obtain accurate NMEs for all
isotopes of experimental interest. However, two of the most important cases,
Te and Xe, lie in the heavy region and have only been
accessible to phenomenological nuclear models. In this work we utilize powerful
advances in ab initio nuclear theory to compute NMEs from the underlying
nuclear and weak forces driving this decay, including the recently discovered
short-range component. We find that ab initio NMEs are generally smaller than
those from nuclear models, challenging the expected reach of future ton-scale
searches as well as claims to probe the inverted hierarchy of neutrino masses.
With this step, ab initio calculations with theoretical uncertainties are now
feasible for all isotopes relevant for next-generation decay
experiments.Comment: 5 pages, 3 figures, supplemental material include
Ni-Cr textured substrates with reduced ferromagnetism for coated conductor applications
A series of biaxially textured Ni(1-x)Cr(x) materials, with compositions x =
0, 7, 9, 11, and 13 at % Cr, have been studied for use as substrate materials
in coated conductor applications with high temperature superconductors. The
magnetic properties were investigated, including the hysteretic loss in a Ni-7
at % Cr sample that was controllably deformed; for comparison, the loss was
also measured in a similarly deformed pure Ni substrate. Complementary X-ray
diffraction studies show that thermo-mechanical processing produces nearly
complete {100} cube texturing, as desired for applications.Comment: PDF only; 19 pp., incl 10 figure
Analytical investigation of magnetic field distributions around superconducting strips on ferromagnetic substrates
The complex-field approach is developed to derive analytical expressions of
the magnetic field distributions around superconducting strips on ferromagnetic
substrates (SC/FM strips). We consider the ferromagnetic substrates as ideal
soft magnets with an infinite magnetic permeability, neglecting the
ferromagnetic hysteresis. On the basis of the critical state model for a
superconducting strip, the ac susceptibility of a SC/FM
strip exposed to a perpendicular ac magnetic field is theoretically
investigated, and the results are compared with those for superconducting
strips on nonmagnetic substrates (SC/NM strips). The real part for
(where is the amplitude of the ac magnetic field,
is the critical current density, and is the thickness of the
superconducting strip) of a SC/FM strip is 3/4 of that of a SC/NM strip. The
imaginary part (or ac loss ) for of a SC/FM
strip is larger than that of a SC/NM strip, even when the ferromagnetic
hysteresis is neglected, and this enhancement of (or ) is due to
the edge effect of the ferromagnetic substrate.Comment: 8 pages, 6 figures, submitted to Phys. Rev.
Low-Rank Decompositions of Three-Nucleon Forces via Randomized Projections
Ab initio calculations for nuclei and nuclear matter are limited by the
computational requirements of processing large data objects. In this work, we
develop low-rank singular value decompositions for chiral three-nucleon
interactions, which dominate these limitations. In order to handle the large
dimensions in representing three-body operators, we use randomized
decomposition techniques. We study in detail the sensitivity of different
three-nucleon topologies to low-rank matrix factorizations. The developed
low-rank three-nucleon interactions are benchmarked in Faddeev calculations of
the triton and ab initio calculations of medium-mass nuclei. Exploiting
low-rank properties of nuclear interactions will be particularly important for
the extension of ab initio studies to heavier and deformed systems, where
storage requirements will exceed the computational capacities of the most
advanced high-performance-computing facilities.Comment: 7 pages, 4 figure
High basal STAT4 balanced by STAT1 induction to control type 1 interferon effects in natural killer cells
The best-characterized type 1 interferon (IFN) signaling pathway depends on signal transducer and activator of transcription 1 (STAT1) and STAT2. The cytokines can, however, conditionally activate all STATs. Regulation of their access to particular signaling pathways is poorly understood. STAT4 is important for IFN-γ induction, and NK cells are major producers of this cytokine. We report that NK cells have high basal STAT4 levels and sensitivity to type 1 IFN–mediated STAT4 activation for IFN-γ production. Increases in STAT1, driven during viral infection by either type 1 IFN or IFN-γ, are associated with decreased STAT4 access. Both STAT1 and STAT2 are important for antiviral defense, but STAT1 has a unique role in protecting against sustained NK cell IFN-γ production and resulting disease. The regulation occurs with an NK cell type 1 IFN receptor switch from a STAT4 to a STAT1 association. Thus, a fundamental characteristic of NK cells is high STAT4 bound to the type 1 IFN receptor. The conditions of infection result in STAT1 induction with displacement of STAT4. These studies elucidate the critical role of STAT4 levels in predisposing selection of specific signaling pathways, define the biological importance of regulation within particular cell lineages, and provide mechanistic insights for how this is accomplished in vivo
Analysis of the contribution of cellular and viral RNA to the packaging of APOBEC3G into HIV-1 virions
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Protein processing characterized by a gel-free proteomics approach
We describe a method for the specific isolation of representative N-terminal peptides of proteins and their proteolytic fragments. Their isolation is based on a gel-free, peptidecentric proteomics approach using the principle of diagonal chromatography. We will indicate that the introduction of an altered chemical property to internal peptides holding a free α-N-terminus results in altered column retention of these peptides, thereby enabling the isolation and further characterization by mass spectrometry of N-terminal peptides. Besides pointing to changes in protein expression levels when performing such proteome surveys in a differential modus, protease specificity and substrate repertoires can be allocated since both are specified by neo-N-termini generated after a protease cleavage event. As such, our gel-free proteomics technology is widely applicable and amenable for a variety of proteome-driven protease degradomics research
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