1,249 research outputs found
Surface modification of hydrophobic polymers for improvement of endothelial cell-surface interactions
The aim of this study is to improve the interaction of endothelial cells with polymers used in vascular prostheses. Polytetrafluoroethylene (PTFE; Teflon) films were treated by means of nitrogen and oxygen plasmas. Depending on the plasma exposure time, modified PTFE surfaces showed water-contact angles of 15¿58° versus 96° for unmodified PTFE. Electron spectroscopy in chemical analysis (ESCA) measurements revealed incorporation of both nitrogenand oxygen-containing groups into the PTFE surfaces, dependent on the plasma composition and exposure time. In-vitro biological evaluation of unmodified and modified PTFE surfaces showed that human endothelial cells, seeded from 20% human serum-containing culture medium, adhered well on to modified PTFE surfaces, but not on to unmodified films. Adhesion of endothelial cells on to expanded PTFE graft material (Gore-Tex) was also stimulated by plasma treatment of this substrate. On plasma-treated expanded PTFE, the adhering endothelial cells formed a monolayer, which covered the textured surface. The latter observation is important in view of the hemocompatibility of vascular grafts seeded with endothelial cells before implantation
Cartoon Computation: Quantum-like computing without quantum mechanics
We present a computational framework based on geometric structures. No
quantum mechanics is involved, and yet the algorithms perform tasks analogous
to quantum computation. Tensor products and entangled states are not needed --
they are replaced by sets of basic shapes. To test the formalism we solve in
geometric terms the Deutsch-Jozsa problem, historically the first example that
demonstrated the potential power of quantum computation. Each step of the
algorithm has a clear geometric interpetation and allows for a cartoon
representation.Comment: version accepted in J. Phys.A (Letter to the Editor
Relative Throughput of the Near-IR Science Instruments for the James Webb Space Telescope as Measured During Ground Testing the Integrated Science Instrument Module
Data were obtained for the purpose of measuring the relative throughput of the Near-IR Science Instruments (SIs) of the James Webb Space Telescope (JWST) as part of the second and third cryogenic-vacuum tests (CV2CV3) of the Integrated Science Instrument Module (ISIM) conducted at the Goddard Space Flight Center (GSFC) in 2014 and 20152016, at the beginning and end of the environmental test program, respectively. This Poster focuses on data obtained as part of the Initial Optical Baseline and as part of the Final Performance test -- two epochs that roughly bracket the CV3 test. The purpose of the test is to trend relative throughput to monitor for any potential changes from gross problems such as contamination or degradation of an optical element. Point source data were taken at a variety of wavelengths for NIRCam Module A and Module B, NIRSpec, NIRISS, Guider 1 and Guider 2 using the Laser Diode (LD) 1.06 micron, LD 1.55 micron, 2.1 micron LED and 3.5 micron LED, as well as for NIRCam Mod A and B and NIRISS using a tungsten source and the F277W, and F480M filters. Spectra were taken using the G140M, G235M, and G395M gratings for NIRSpec, the GRISMR grism for NIRCam Mod A and B and the GR150C grism for NIRISS. The results of these measurements are compared to what would be expected given the efficiency of each of the optical elements in each SI. Although these data were taken as a check against gross problems, they can also be used to provide the first relative throughput estimate for each SI through the various filters source wavelengths measured in their flight-like configurations
Universal neural field computation
Turing machines and G\"odel numbers are important pillars of the theory of
computation. Thus, any computational architecture needs to show how it could
relate to Turing machines and how stable implementations of Turing computation
are possible. In this chapter, we implement universal Turing computation in a
neural field environment. To this end, we employ the canonical symbologram
representation of a Turing machine obtained from a G\"odel encoding of its
symbolic repertoire and generalized shifts. The resulting nonlinear dynamical
automaton (NDA) is a piecewise affine-linear map acting on the unit square that
is partitioned into rectangular domains. Instead of looking at point dynamics
in phase space, we then consider functional dynamics of probability
distributions functions (p.d.f.s) over phase space. This is generally described
by a Frobenius-Perron integral transformation that can be regarded as a neural
field equation over the unit square as feature space of a dynamic field theory
(DFT). Solving the Frobenius-Perron equation yields that uniform p.d.f.s with
rectangular support are mapped onto uniform p.d.f.s with rectangular support,
again. We call the resulting representation \emph{dynamic field automaton}.Comment: 21 pages; 6 figures. arXiv admin note: text overlap with
arXiv:1204.546
Deep Underground Science and Engineering Laboratory - Preliminary Design Report
The DUSEL Project has produced the Preliminary Design of the Deep Underground
Science and Engineering Laboratory (DUSEL) at the rehabilitated former
Homestake mine in South Dakota. The Facility design calls for, on the surface,
two new buildings - one a visitor and education center, the other an experiment
assembly hall - and multiple repurposed existing buildings. To support
underground research activities, the design includes two laboratory modules and
additional spaces at a level 4,850 feet underground for physics, biology,
engineering, and Earth science experiments. On the same level, the design
includes a Department of Energy-shepherded Large Cavity supporting the Long
Baseline Neutrino Experiment. At the 7,400-feet level, the design incorporates
one laboratory module and additional spaces for physics and Earth science
efforts. With input from some 25 science and engineering collaborations, the
Project has designed critical experimental space and infrastructure needs,
including space for a suite of multidisciplinary experiments in a laboratory
whose projected life span is at least 30 years. From these experiments, a
critical suite of experiments is outlined, whose construction will be funded
along with the facility. The Facility design permits expansion and evolution,
as may be driven by future science requirements, and enables participation by
other agencies. The design leverages South Dakota's substantial investment in
facility infrastructure, risk retirement, and operation of its Sanford
Laboratory at Homestake. The Project is planning education and outreach
programs, and has initiated efforts to establish regional partnerships with
underserved populations - regional American Indian and rural populations
Quantum Aspects of Semantic Analysis and Symbolic Artificial Intelligence
Modern approaches to semanic analysis if reformulated as Hilbert-space
problems reveal formal structures known from quantum mechanics. Similar
situation is found in distributed representations of cognitive structures
developed for the purposes of neural networks. We take a closer look at
similarites and differences between the above two fields and quantum
information theory.Comment: version accepted in J. Phys. A (Letter to the Editor
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DNA methylation-based classification of central nervous system tumours.
Accurate pathological diagnosis is crucial for optimal management of patients with cancer. For the approximately 100 known tumour types of the central nervous system, standardization of the diagnostic process has been shown to be particularly challenging-with substantial inter-observer variability in the histopathological diagnosis of many tumour types. Here we present a comprehensive approach for the DNA methylation-based classification of central nervous system tumours across all entities and age groups, and demonstrate its application in a routine diagnostic setting. We show that the availability of this method may have a substantial impact on diagnostic precision compared to standard methods, resulting in a change of diagnosis in up to 12% of prospective cases. For broader accessibility, we have designed a free online classifier tool, the use of which does not require any additional onsite data processing. Our results provide a blueprint for the generation of machine-learning-based tumour classifiers across other cancer entities, with the potential to fundamentally transform tumour pathology
Wind action on water standing in a laboratory channel
CEP6566-GMHEJP14a, CER65GMH-EJP40a.NCAR preprint-memo, PM # 135.Includes bibliographical references.The processes of wave and current development resulting from wind action on initially standing water have been investigated in a wind-water tunnel. The mean air flow over wavy water was examined along with the variation of several properties of the water motion with fetch, water depth, and wind speed. Measurements of phase speed and length of significant waves, the standard deviation of the water sur face, the average surface drift, the autocorrelation of surface displacement and the frequency spectra of the wind waves are reported. The experimental results indicate that (a) the air motion in the channel follows a three dimensional pattern characteristic of wind tunnels of rectangular cross-section; (b) the wind waves generated in the channel travel downstream at approximately the same phase speed as gravity waves of small amplitude, provided the effect of the drift current is taken into account; (c) the average drag coefficients for the action of the wind on the water surface increase with increasing wind speed, and these data are essentially the same as the results of previous investigators; (d) the autocorrelations of surface displacement and frequency spectra are consistent with the visual observations that the wind waves in the channel consist of nearly regular primary waves on which are superimposed smaller ripples; (e) energy in the high frequency range in the spectra tends to approach an equilibrium distribution rather quickly while the lower frequency components initially grow exponentially with increasing fetch but, later, tend to reach a state of equilibrium; and (f) a similarity shape for the frequency spectra developed
LISA pathfinder optical interferometry
The LISA Technology Package (LTP) aboard of LISA pathfinder mission is dedicated to demonstrate and verify key technologies for LISA, in particular drag free control, ultra-precise laser interferometry and gravitational sensor. Two inertial sensor, the optical interferometry in between combined with the dimensional stable Glass ceramic Zerodur structure are setting up the LTP. The validation of drag free operation of the spacecraft is planned by measuring laser interferometrically the relative displacement and tilt between two test masses (and the optical bench) with a noise levels of 10pm/[square root of]Hz and 10 nrad/[square root of]Hz between 3mHz and 30mHz. This performance and additionally overall environmental tests was currently verified on EM level. The OB structure is able to support two inertial sensors ([approximate]17kg each) and to withstand 25 g design loads as well as 0...40°C temperature range. Optical functionality was verified successfully after environmental tests. The engineering model development and manufacturing of the optical bench and interferometry hardware and their verification tests will be presented
Still a long way to go to achieve multidisciplinarity for the benefit of patients: commentary on the ESMO position paper (Annals Oncology Jan;25(1): 9-15, 2014)
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