An adaptive inelastic magnetic mirror for Bose-Einstein condensates

We report the reflection and focussing of a Bose-Einstein condensate by a new pulsed magnetic mirror. The mirror is adaptive, inelastic, and of extremely high optical quality. The deviations from specularity are less than 0.5 mrad rms, making this the best atomic mirror demonstrated to date. We have also used the mirror to realize the analog of a beam-expander, producing an ultra-cold collimated fountain of matter wavesComment: 4 pages, 4 figure

Measurement of Bottom versus Charm as a Function of Transverse Momentum with Electron-Hadron Correlations in p+p Collisions at sqrt(s)=200 GeV

The momentum distribution of electrons from semi-leptonic decays of charm and bottom for mid-rapidity |y|<0.35 in p+p collisions at sqrt(s)=200 GeV is measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) over the transverse momentum range 2 < p_T < 7 GeV/c. The ratio of the yield of electrons from bottom to that from charm is presented. The ratio is determined using partial D/D^bar --> e^{+/-} K^{-/+} X (K unidentified) reconstruction. It is found that the yield of electrons from bottom becomes significant above 4 GeV/c in p_T. A fixed-order-plus-next-to-leading-log (FONLL) perturbative quantum chromodynamics (pQCD) calculation agrees with the data within the theoretical and experimental uncertainties. The extracted total bottom production cross section at this energy is \sigma_{b\b^bar}= 3.2 ^{+1.2}_{-1.1}(stat) ^{+1.4}_{-1.3}(syst) micro b.Comment: 432 authors, 6 pages text, 3 figures. Submitted to Phys. Rev. Lett. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas

Although the MYC oncogene has been implicated in cancer, a systematic assessment of alterations of MYC, related transcription factors, and co-regulatory proteins, forming the proximal MYC network (PMN), across human cancers is lacking. Using computational approaches, we define genomic and proteomic features associated with MYC and the PMN across the 33 cancers of The Cancer Genome Atlas. Pan-cancer, 28% of all samples had at least one of the MYC paralogs amplified. In contrast, the MYC antagonists MGA and MNT were the most frequently mutated or deleted members, proposing a role as tumor suppressors. MYC alterations were mutually exclusive with PIK3CA, PTEN, APC, or BRAF alterations, suggesting that MYC is a distinct oncogenic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such as immune response and growth factor signaling; chromatin, translation, and DNA replication/repair were conserved pan-cancer. This analysis reveals insights into MYC biology and is a reference for biomarkers and therapeutics for cancers with alterations of MYC or the PMN. We present a computational study determining the frequency and extent of alterations of the MYC network across the 33 human cancers of TCGA. These data, together with MYC, positively correlated pathways as well as mutually exclusive cancer genes, will be a resource for understanding MYC-driven cancers and designing of therapeutics

Sensors for chemical detection based on top-down fabricated polycrystalline silicon nanowires

Semiconducting Silicon (Si) nanowires (NWs) have been widely investigated for their potential to function as highly sensitive and selective sensors for both chemical and biological purposes. A key point of this sensing method is to be real-time and label-free. Several interesting sensing assays have been demonstrated such as sensing of ions, proteins, DNA and viruses[1-3]. The available approaches of silicon nanowire fabrication usually use some advanced lithographic techniques i.e., deep-UV, electron-beam or nanoimprint lithography to pattern silicon nanowires on SOI wafers. Recently, spacer nanowires patterned by a conventional anisotropic dry etch were used to form transistors. While this approach has the advantage of CMOS-compatibility, these techniques are extremely expensive and accessible only to large-scale integrated circuit manufacturers. While this approach delivers a cheap route for nanowire definition, nanowire volume control across the wafer remains challenging as the nanowire sidewall region generally receives unwanted etching

Low cost nanowire biosensor fabrication using thin film amorphous silicon crystallisation technologies

Recently, Si nanowires are receiving much attention for biosensing because they offer the prospect of real-time, label-free, high sensitivity sensing. The most popular approach to silicon nanowire fabrication uses electron-beam lithography to define silicon nanowires on SOI wafers. While this approach has the advantage of CMOS-compatibility, it has the disadvantage of high cost, because both the lithography and the SOI wafers are expensive. In this paper we demonstrate a low cost, CMOS-compatible fabrication process for silicon nanowire biosensors, which is based on thin film transistor technology. The key steps in the fabrication process are the deposition of an amorphous Si layer over a sharp step in an insulating film and an anisotropic Si etch to create a silicon nanowire on the side of the step. The anisotropic etch was performed on an ICP etcher using the Bosch process, which gives well-defined, rectangular amorphous silicon nanowires with a geometry of 80 x 120 nm, measured by cross-sectional SEM. Metal induced lateral crystallization is then used to crystallize the amorphous silicon at a temperature around 500°C to create polycrystalline silicon nanowires. The approach used for nanowire functionalisation produces a maleimide activated surface that is amenable to the immobilization of biomolecules with a free thiol

Polycrystalline silicon nanowires patterned by top-down lithography for biosensor applications

Recently, Si nanowires are receiving much attention for biosensing because they offer the prospect of realtime, label-free, high sensitivity sensing. The most popular approach to silicon nanowire fabrication uses electron-beam lithography to pattern silicon nanowires on SOI wafers. While this approach has the advantage of CMOS-compatibility, it has the disadvantage of high cost, because both the lithography and the SOI wafers are expensive. Recently, spacer nanowires patterned by a conventional anisotropic dry etch were used to form transistors, which tends to give a triangular shape. In this paper, we demonstrate a low cost, CMOS-compatible fabrication process of polycrystalline silicon nanowires for biosensor applications using a Bosch dry etch process. The nanowires produced in this way have a rectangular shape, which gives good control over the nanowire width -height and electrical characteristics