14,160 research outputs found
Non-Hermitian robust edge states in one-dimension: Anomalous localization and eigenspace condensation at exceptional points
Capital to topological insulators, the bulk-boundary correspondence ties a
topological invariant computed from the bulk (extended) states with those at
the boundary, which are hence robust to disorder. Here we put forward an
ordering unique to non-Hermitian lattices, whereby a pristine system becomes
devoid of extended states, a property which turns out to be robust to disorder.
This is enabled by a peculiar type of non-Hermitian degeneracy where a
macroscopic fraction of the states coalesce at a single point with geometrical
multiplicity of , that we call a phenomenal point.Comment: 6 pages, 4 figure
INFRARED IMAGING AND COMPUTERIZED TOMOGRAPHY IN BREAST CANCER: CASE STUDY
This work presents a case study of a 75-year-old woman breast withcancer. The investigation process used infrared image, mammography,computerized tomography (CT) and ultrasound guided biopsy toassess, stage and final diagnostic of the tumor. Each one of theseevaluations brings an isolated piece of information that results in thecorrect diagnostic, and treatment. As early diagnostic of breast cancergoes towards improvement in diagnostics and better therapeutics, it isreasonable to state that breast cancer diagnostics must be achieved asearly as possible. An association between infrared image abnormalitiesand computerized tomography is acknowledged and is assumed that acorrelation could exist. The technical literature demonstrated thattumor depth could be inferred from infrared images, but criticalinformation such as breast perfusion for accurate predictions are notavailable yet. Considering that a mathematical model could modelbreast perfusion, this study proposes that tumor morphology and depthin breast cancer could be adequately determined using mathematicalmodeling, infrared imaging, and computerized tomography incomplementary actions
Numerical modelling of cutting forces in gear skiving
Gear skiving is a high-performance machining process for gear manufacturing. Due to its complex kinematics, the local cutting conditions vary during tool engagement. Particularly, the local rake angle can reach highly negative values, which have a significant effect on the cutting force. In this paper, the Kienzle force model with additional coefficients was implemented in a numerical model to calculate local cutting forces considering the influence of local rake angle. The experimental validation based on total cutting forces shows good results and indicates an increase of model accuracy for a wide parameter range by considering the rake angle variation
Star Formation in the Field and Clusters of NGC 5253
We investigate the star formation history of both the bright star clusters
and the diffuse `field star' population in the dwarf starburst galaxy NGC 5253
using STIS longslit ultraviolet spectroscopy. Our slit covers a physical area
of 370 x 1.6 pc and includes 8 apparent clusters and several inter-cluster
regions of diffuse light which we take to be the field. The diffuse light
spectrum lacks the strong O-star wind features which are clearly visible in
spectra of the brightest clusters. This discrepancy provides compelling
evidence that the diffuse light is not reflected light from nearby clusters,
but originates in a UV-bright field star population, and it raises the issue of
whether the star formation process may be operating differently in the field
than in clusters. We compare our spectra to STARBURST99 evolutionary synthesis
models which incorporate a new low metallicity atlas of O-star spectra. We
favor a scenario which accounts for the paucity of O-stars in the field without
requiring the field to have a different IMF than the clusters: stellar clusters
form continuously and then dissolve on ~10 Myr timescales and disperse their
remaining stars into the field. We consider the probable contribution of an
O-star deficient field population to the spatially unresolved spectra of high
redshift galaxies. (Abridged)Comment: 26 pages, 10 figures, accepted for publication in Ap
Direct replacement of antibodies with molecularly imprinted polymer (MIP) nanoparticles in ELISA - development of a novel assay for vancomycin
A simple and straightforward technique for coating microplate wells with molecularly imprinted polymer nanoparticles (nanoMIPs) to develop ELISA type assays is presented here for the first time. NanoMIPs were synthesized by a solid phase approach with immobilized vancomycin (template) and characterized using Biacore 3000, dynamic light scattering and electron microscopy. Immobilization, blocking and washing conditions were optimized in microplate format. The detection of vancomycin was achieved in competitive binding experiments with a HRP-vancomycin conjugate. The assay was capable of measuring vancomycin in buffer and in blood plasma within the range 0.001-70 nM with a detection limit of 0.0025 nM (2.5 pM). The sensitivity of the assay was three orders of magnitude better than a previously described ELISA based on antibodies. In these experiments nanoMIPs have shown high affinity and minimal interference from blood plasma components. Immobilized nanoMIPs were stored for 1 month at room temperature without any detrimental effects to their binding properties. The high affinity of nanoMIPs and the lack of a requirement for cold chain logistics make them an attractive alternative to traditional antibodies used in ELIS
SIGMA and XTE observations of the soft X-ray transient XTEJ1755-324
We present observations of the X-ray transient XTEJ1755-324 performed during
summer 1997 with the XTE satellite and with the SIGMA hard X-ray telescope
onboard the GRANAT observatory. The source was first detected in soft X-rays
with XTE on July 25 1997 with a rather soft X-ray spectrum and its outburst was
monitored in soft X-rays up to November 1997. On September 16 it was first
detected in hard X-rays by the French soft gamma ray telescope SIGMA during a
Galactic Center observation. The flux was stronger on September 16 and 17
reaching a level of about 110 mCrab in the 40-80 keV energy band. On the same
days the photon index of the spectrum was determined to be alpha =-2.3 +/- 0.9
(1 sigma error) while the 40-150 keV luminosity was about 8 x 10^{36} erg/s for
a distance of 8.5 kpc. SIGMA and XTE results on this source indicate that this
source had an ultrasoft-like state during its main outburst and a harder
secondary outburst in September. These characteristics make the source similar
to X-Nova Muscae 1991, a well known black hole candidate.Comment: 19 pages LaTeX, 6 Postscript figures included, Accepted by
Astrophysical Journa
A systematic survey of millimetre-wavelength flaring variability of Young Stellar Objects in the Orion Nebula Cluster
High-energy processes are ubiquitous even in the earliest stages of
protostellar evolution. Motivated by the results of our systematic search for
intense centimeter radio flares in Young Stellar Objects (YSOs) and by rare
findings of strong millimeter-wavelength variability, we have conducted a
systematic search for such variability in the Orion Nebula Cluster (ONC) using
Atacama Large Millimeter/submillimeter Array (ALMA). Rapid variability on
timescales of minutes to hours in the (centimeter)millimeter-wavelength range
indicates (gyro)synchrotron radiation. Additionally, mass accretion will also
affect the millimeter-wavelength luminosity but typically on longer timescales.
Beyond studies of individual YSOs, our characterization of strong
millimeter-wavelength variability with ALMA in the ONC sets first systematic
constraints on the occurrence of such variability in a large number of YSOs
(130). We report the discovery of an order of magnitude millimeter-flare
within just a few minutes from a known YSO previously reported as a radio
flaring source at cm-wavelengths (the "ORBS'' source). We also present an
assessment of the systematic variability effects caused by the use of
time-sliced imaging of a complex region. These are mostly due to the impact of
a changing synthesized beam throughout the observations. We use simulated ALMA
observations to reproduce and quantify these effects and set a lower limit for
the variability that can be studied using our method in a complex region such
as the ONC. Our results demonstrate that the utility of time domain analysis of
YSOs extends into the millimeter-wavelength range, potentially interfering with
the conversion of observed fluxes into dust masses.Comment: 15 pages, 8 figures, accepted for publication in MNRA
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