1,700 research outputs found
Heat Conduction Process on Community Networks as a Recommendation Model
Using heat conduction mechanism on a social network we develop a systematic
method to predict missing values as recommendations. This method can treat very
large matrices that are typical of internet communities. In particular, with an
innovative, exact formulation that accommodates arbitrary boundary condition,
our method is easy to use in real applications. The performance is assessed by
comparing with traditional recommendation methods using real data.Comment: 4 pages, 2 figure
MS 016 Guide to Russell J. Blattner, MD Papers (1936-1985)
The Blattner collection contains Dr. Blattner\u27s research work throughout his career in St. Louis and Houston. It contains photographs, research materials, reprints, and publications. It offers a record of Dr. Blattner\u27s professional life and contains no personal or family records. Collection materials date from 1936-1985. See more at MS 016
Ferromagnetism in (In,Mn)As Diluted Magnetic Semiconductor Thin Films Grown by Metalorganic Vapor Phase Epitaxy
In1-xMnxAs diluted magnetic semiconductor (DMS) thin films have been grown
using metalorganic vapor phase epitaxy (MOVPE).
Tricarbonyl(methylcyclopentadienyl)manganese was used as the Mn source.
Nominally single-phase, epitaxial films were achieved with Mn content as high
as x=0.14 using growth temperatures Tg>475 C. For lower growth temperatures and
higher Mn concentrations, nanometer scale MnAs precipitates were detected
within the In1-xMnxAs matrix. Magnetic properties of the films were
investigated using a superconducting quantum interference device (SQUID)
magnetometer. Room-temperature ferromagnetic order was observed in a sample
with x=0.1. Magnetization measurements indicated a Curie temperature of 333 K
and a room-temperature saturation magnetization of 49 emu/cm^3. The remnant
magnetization and the coercive field were small, with values of 10 emu/cm^3 and
400 Oe, respectively. A mechanism for this high-temperature ferromagnetism is
discussed in light of the recent theory based on the formation of small
clusters of a few magnetic atoms.Comment: 5 pages, 5 figures, accepted for publication in JVST
Local Environment of Ferromagnetically Ordered Mn in Epitaxial InMnAs
The magnetic properties of the ferromagnetic semiconductor In0.98Mn0.02As
were characterized by x-ray absorption spectroscopy and x-ray magnetic circular
dichroism. The Mn exhibits an atomic-like L2,3 absorption spectrum that
indicates that the 3d states are highly localized. In addition, a large
dichroism at the Mn L2,3 edge was observed from 5-300 K at an applied field of
2T. A calculated spectrum assuming atomic Mn2+ yields the best agreement with
the experimental InMnAs spectrum. A comparison of the dichroism spectra of MnAs
and InMnAs show clear differences suggesting that the ferromagnetism observed
in InMnAs is not due to hexagonal MnAs clusters. The temperature dependence of
the dichroism indicates the presence of two ferromagnetic species, one with a
transition temperature of 30 K and another with a transition temperature in
excess of 300 K. The dichroism spectra are consistent with the assignment of
the low temperature species to random substitutional Mn and the high
temperature species to Mn near-neighbor pairs.Comment: 10 pages, 4 figures, accepted by Applied Physics Letter
Antimony doping of Si layers grown by solid-phase epitaxy
We report here that layers of Si formed by solid-phase epitaxial growth (SPEG) can be doped intentionally. The sample consists initially of an upper layer of amorphous Si (~1 µm thick), a very thin intermediate layer of Sb (nominally 5 Å), and a thin lower layer of Pd (~500 Å), all electron-gun deposited on top of a single-crystal substrate (1–10 Ω cm, p type, orientation). After a heating cycle which induces epitaxial growth, electrically active Sb atoms are incorporated into the SPEG layer, as shown by the following facts: (a) the SPEG layer forms a p-n junction against the p-type substrate, (b) the Hall effect indicates strong n-type conduction of the layer, and (c) Auger electron spectra reveal the presence of Sb in the layer
Transient down-regulation of beta1 integrin subtypes on kidney carcinoma cells is induced by mechanical contact with endothelial cell membranes
Adhesion molecules of the integrin beta1 family are thought to be involved in the malignant progression renal cell carcinoma (RCC). Still, it is not clear how they contribute to this process. Since the hematogenous phase of tumour dissemination is the rate-limiting step in the metastatic process, we explored beta1 integrin alterations on several RCC cell lines (A498, Caki1, KTC26) before and after contacting vascular endothelium in a tumour-endothelium (HUVEC) co-culture assay. Notably, alpha2, alpha3 and alpha5 integrins became down-regulated immediately after the tumour cells attached to HUVEC, followed by re-expression shortly thereafter. Integrin down-regulation on RCC cells was caused by direct contact with endothelial cells, since the isolated endothelial membrane fragments but not the cell culture supernatant contributed to the observed effects. Integrin loss was accompanied by a reduced focal adhesion kinase (FAK) expression, FAK activity and diminished binding of tumour cells to matrix proteins. Furthermore, intracellular signalling proteins RCC cells were altered in the presence of HUVEC membrane fragments, in particular 14-3-3 epsilon, ERK2, PKCdelta, PKCepsilon and RACK1, which are involved in regulating tumour cell motility. We, therefore, speculate that contact of RCC cells with the vascular endothelium converts integrin-dependent adhesion to integrin-independent cell movement. The process of dynamic integrin regulation may be an important part in tumour cell migration strategy, switching the cells from being adhesive to becoming motile and invasive
Using cascading Bloom filters to improve the memory usage for de Brujin graphs
De Brujin graphs are widely used in bioinformatics for processing
next-generation sequencing data. Due to a very large size of NGS datasets, it
is essential to represent de Bruijn graphs compactly, and several approaches to
this problem have been proposed recently. In this work, we show how to reduce
the memory required by the algorithm of [3] that represents de Brujin graphs
using Bloom filters. Our method requires 30% to 40% less memory with respect to
the method of [3], with insignificant impact to construction time. At the same
time, our experiments showed a better query time compared to [3]. This is, to
our knowledge, the best practical representation for de Bruijn graphs.Comment: 12 pages, submitte
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