32,696 research outputs found
The power of neural nets
Implementation of the Hopfield net which is used in the image processing type of applications where only partial information about the image may be available is discussed. The image classification type of algorithm of Hopfield and other learning algorithms, such as the Boltzmann machine and the back-propagation training algorithm, have many vital applications in space
A technique for correcting ERTS data for solar and atmospheric effects
The author has identified the following significant results. Based on processing ERTS CCTs and ground truth measurements collected on Michigan test site for January through June 1973 the following results are reported: (1) atmospheric transmittance varies from: 70 to 85% in band 4, 77 to 90% in band 5, 80 to 94% in band 6, and 84 to 97% in band 7 for one air mass; (2) a simple technique was established to determine atmospheric scattering seen by ERTS-1 from ground-based measurements of sky radiance. For March this scattering was found to be equivalent to that produced by a target having a reflectance of 11% in band 4, 5% in band 5, 3% in band 6, and 1% in band 7; (3) computer ability to classify targets under various atmospheric conditions was determined. Classification accuracy on some targets (i.e. bare soil, tended grass, etc.) hold up even under the most severe atmospheres encountered, while performance on other targets (trees, urban, rangeland, etc.) degrades rapidly when atmospheric conditions change by the smallest amount
Simulation of Thematic Mapper performance as a function of sensor scanning parameters
The investigation and results of the Thematic Mapper Instrument Performance Study are described. The Thematic Mapper is the advanced multispectral scanner initially planned for the Earth Observation Satellite and now planned for LANDSAT D. The use of existing digital airborne scanner data obtained with the Modular Multispectral Scanner (M2S) at Bendix provided an opportunity to simulate the effects of variation of design parameters of the Thematic Mapper. Analysis and processing of this data on the Bendix Multispectral Data Analysis System were used to empirically determine categorization performance on data generated with variations of the sampling period and scan overlap parameters of the Thematic Mapper. The Bendix M2S data, with a 2.5 milliradian instantaneous field of view and a spatial resolution (pixel size) of 10-m from 13,000 ft altitude, allowed a direct simulation of Thematic Mapper data with a 30-m resolution. The flight data chosen were obtained on 30 June 1973 over agricultural test sites in Indiana
Computer Mapping of Water Quality in Saginaw Bay with LANDSAT Digital Data
The author has identified the following significant results. LANDSAT digital data and ground truth measurements for Saginaw Bay (Lake Huron), Michigan, for 31 July 1975 were correlated by stepwise linear regression and the resulting equations used to estimate invisible water quality parameters in nonsampled areas. Chloride, conductivity, total Kjeldahl nitrogen, total phosphorus, and chlorophyll a were best correlated with the ratio of LANDSAT Band 4 to Band 5. Temperature and Secchi depth correlate best with Band 5
Large-amplitude chirped coherent phonons in tellurium mediated by ultrafast photoexcited carrier diffusion
We report femtosecond time-resolved reflectivity measurements of coherent
phonons in tellurium performed over a wide range of temperatures (3K to 296K)
and pump laser intensities. A totally symmetric A coherent phonon at 3.6
THz responsible for the oscillations in the reflectivity data is observed to be
strongly positively chirped (i.e, phonon time period decreases at longer
pump-probe delay times) with increasing photoexcited carrier density, more so
at lower temperatures. We show for the first time that the temperature
dependence of the coherent phonon frequency is anomalous (i.e, increasing with
increasing temperature) at high photoexcited carrier density due to
electron-phonon interaction. At the highest photoexcited carrier density of
1.4 10cm and the sample temperature of 3K, the
lattice displacement of the coherent phonon mode is estimated to be as high as
0.24 \AA. Numerical simulations based on coupled effects of optical
absorption and carrier diffusion reveal that the diffusion of carriers
dominates the non-oscillatory electronic part of the time-resolved
reflectivity. Finally, using the pump-probe experiments at low carrier density
of 6 10 cm, we separate the phonon anharmonicity to
obtain the electron-phonon coupling contribution to the phonon frequency and
linewidth.Comment: 22 pages, 6 figures, submitted to PR
Laparoscopic bilateral gonadectomy in a case of turner syndrome with 45XO/46XY genotype
Turner syndrome is one of the common chromosomal aberrations which manifests in a female as multiple phenotypic disorders usually presenting as a case of primary amenorrhea. Many of these patients display mosaicism on karyotyping and a presence of Y chromosomal material indicates high risk of gonadoblastoma and gonadectomy is indicated which is best achieved by laparoscopy. This is a case of 21-year-old female phenotype referred as a case of primary amenorrhea diagnosed as Turner syndrome with 46XY mosaicism. Laparoscopic bilateral salpingoophorectomy was done. In patients of primary amenorrhea karyotyping should be evaluated and if Y chromosome detected these patients should be subjected to gonadectomy after proper risk counselling about malignancy
Laparoscopic management of heterotopic pregnancy in an IVF conception
Heterotopic Pregnancy cases are on the rise in the era of Artificial Reproductive Techniques and managing these pregnancies can be challenging especially in safeguarding the precious intrauterine pregnancy. These were traditionally managed by laparotomy and there are few cases reported wherein salpingectomy is done laparoscopically. We would like to report this case of a 7 weeks intrauterine pregnancy with 5 weeks tubal ectopic treated by laparoscopic salpingectomy under spinal anaesthesia while safeguarding the intrauterine viable gestation. In the light of increased incidence of abnormal implantations and growing demand and expertise of minimally invasive surgeries, laparoscopy is the treatment of choice for heterotopic pregnancies, especially in the interest of the intrauterine pregnancy
Scaling and Formulary cross sections for ion-atom impact ionization
The values of ion-atom ionization cross sections are frequently needed for
many applications that utilize the propagation of fast ions through matter.
When experimental data and theoretical calculations are not available,
approximate formulas are frequently used. This paper briefly summarizes the
most important theoretical results and approaches to cross section calculations
in order to place the discussion in historical perspective and offer a concise
introduction to the topic. Based on experimental data and theoretical
predictions, a new fit for ionization cross sections is proposed. The range of
validity and accuracy of several frequently used approximations (classical
trajectory, the Born approximation, and so forth) are discussed using, as
examples, the ionization cross sections of hydrogen and helium atoms by various
fully stripped ions.Comment: 46 pages, 8 figure
Comparative Proteomic Profiling of Methicillin‐Susceptible and Resistant Staphylococcus aureus
Purpose
Staphylococcus aureus is a highly successful human pathogen responsible for wide range of infections. In this study, we provide insights into the virulence, pathogenicity, and antimicrobial resistance determinants of methicillin susceptible and methicillin resistant Staphylococcus aureus (MSSA; MRSA) recovered from non‐healthcare environments.
Experiment design
Three environmental MSSA and three environmental MRSA were selected for proteomic profiling using iTRAQ MS/MS. Gene Ontology (GO) Annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway Annotation were applied to interpret the functions of the proteins detected.
Results
792 proteins were identified in MSSA and MRSA. Comparative analysis of MRSA and MSSA revealed that 8 of out 792 proteins were up‐regulated and 156 were down‐regulated. Proteins that had differences in abundance were predominantly involved in catalytic and binding activity. Among 164 differently abundant proteins, 29 were involved in pathogenesis, antimicrobial resistance, stress response, mismatch repair and cell wall synthesis. Twenty‐two proteins associated with pathogenicity, including spa, sbi, clfA and dlt were up‐regulated in MRSA. Moreover, the up‐regulated pathogenic protein entC2 in MSSA was determined to be a super antigen potentially capable of triggering toxic shock syndrome in the host.
Conclusions
Enhanced pathogenicity, antimicrobial resistance and stress response were observed in MRSA compared to MSSA
() spectroscopy using Cornell potential
The mass spectra and decay properties of heavy quarkonia are computed in
nonrelativistic quark-antiquark Cornell potential model. We have employed the
numerical solution of Schr\"odinger equation to obtain their mass spectra using
only four parameters namely quark mass (, ) and confinement strength
(, ). The spin hyperfine, spin-orbit and tensor
components of the one gluon exchange interaction are computed perturbatively to
determine the mass spectra of excited , , and states. Digamma,
digluon and dilepton decays of these mesons are computed using the model
parameters and numerical wave functions. The predicted spectroscopy and decay
properties for quarkonia are found to be consistent with available experimental
observations and results from other theoretical models. We also compute mass
spectra and life time of the meson without additional parameters. The
computed electromagnetic transition widths of heavy quarkonia and mesons
are in tune with available experimental data and other theoretical approaches
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