Radar cross section lectures

NASA Astrophysics Data System (ADS)

Fuhs, A. E.

A comprehensive account is given of the principles that can be applied in military aircraft configuration studies to minimize the radar cross section (RCS) that will be presented by the resulting design to advanced radars under various mission circumstances. It is noted that, while certain ECM techniques can be nullified by improved enemy electronics in a very short time, RCS reductions may require as much as a decade of radar development before prior levels of detectability can be reestablished by enemy defenses. Attention is given to RCS magnitude determinants, inverse scattering, the polarization and scattering matrix, the RCSs of flat plates and conducting cylinders, and antenna geometry and beam patterns.

Research into Influence of Gaussian Beam on Terahertz Radar Cross Section of a Semicircular Boss

NASA Astrophysics Data System (ADS)

Li, Hui-Yu; Li, Qi; She, Jian-Yu; Zhao, Yong-Peng; Chen, De-Ying; Wang, Qi

2013-08-01

In radar cross section (RCS) calculation of a rough surface, the model can be simplified into the scattering of geometrically idealized bosses on a surface. Thus the problem of the RCS calculation of a rough surface is changed to the RCS calculation of the semicircular boss. The RCS measurement of scale model can help save time and money. The utilization of terahertz in RCS is attractive because of its special properties: the wavelength of the terahertz wave can help limit the size of the model in a suitable range in the measurement of the scale model and get more detailed data in the measurement of the real object. However, usually the incident beam of a terahertz source is a Gaussian beam; in the theoretical RCS estimation, usually a plane wave is assumed as the incident beam for sake of simplicity which may lead to an error between the measurement and calculation results. In this paper, the method of images is used to calculate the RCS of a semicircular boss at 2.52 THz and the results are compared to the one calculated when the incident beam is a plane wave.

FDTD simulation of radar cross section reduction by a collisional inhomogeneous magnetized plasma

NASA Astrophysics Data System (ADS)

Foroutan, V.; Azarmanesh, M. N.; Foroutan, G.

2018-02-01

The recursive convolution finite difference time domain method is addressed in the scattered field formulation and employed to investigate the bistatic radar cross-section (RCS) of a square conductive plate covered by a collisional inhomogeneous magnetized plasma. The RCS is calculated for two different configurations of the magnetic field, i.e., parallel and perpendicular to the plate. The results of numerical simulations show that, for a perpendicularly applied magnetic field, the backscattered RCS is significantly reduced when the magnetic field intensity coincides with the value corresponding to the electron cyclotron resonance. By increasing the collision frequency, the resonant absorption is suppressed, but due to enhanced wave penetration and bending, the reduction in the bistatic RCS is improved. At very high collision frequencies, the external magnetic field has no significant impact on the bistatic RCS reduction. Application of a parallel magnetic field has an adverse effect near the electron cyclotron resonance and results in a large and asymmetric RCS profile. But, the problem is resolved by increasing the magnetic field and/or the collision frequency. By choosing proper values of the collision frequency and the magnetic field intensity, a perpendicular magnetic field can be effectively used to reduce the bistatic RCS of a conductive plate.

Review of FD-TD numerical modeling of electromagnetic wave scattering and radar cross section

NASA Technical Reports Server (NTRS)

Taflove, Allen; Umashankar, Korada R.

1989-01-01

Applications of the finite-difference time-domain (FD-TD) method for numerical modeling of electromagnetic wave interactions with structures are reviewed, concentrating on scattering and radar cross section (RCS). A number of two- and three-dimensional examples of FD-TD modeling of scattering and penetration are provided. The objects modeled range in nature from simple geometric shapes to extremely complex aerospace and biological systems. Rigorous analytical or experimental validatons are provided for the canonical shapes, and it is shown that FD-TD predictive data for near fields and RCS are in excellent agreement with the benchmark data. It is concluded that with continuing advances in FD-TD modeling theory for target features relevant to the RCS problems and in vector and concurrent supercomputer technology, it is likely that FD-TD numerical modeling will occupy an important place in RCS technology in the 1990s and beyond.

An Ultra-wideband and Polarization-independent Metasurface for RCS Reduction

PubMed Central

Su, Pei; Zhao, Yongjiu; Jia, Shengli; Shi, Wenwen; Wang, Hongli

2016-01-01

In this paper, an ultra-wideband and polarization-independent metasurface for radar cross section (RCS) reduction is proposed. The unit cell of the metasurface operates in a linear cross-polarization scheme in a broad band. The phase and amplitude of cross-polarized reflection can be separately controlled by its geometry and rotation angle. Based on the diffuse reflection theory, a 3-bit coding metasurface is designed to reduce the RCS in an ultra-wide band. The wideband property of the metasurface benefits from the wideband cross polarization conversion and flexible phase modulation. In addition, the polarization-independent feature of the metasurface is achieved by tailoring the rotation angle of each element. Both the simulated and measured results demonstrate that the proposed metasurface can reduce the RCS significantly in an ultra-wide frequency band for both normal and oblique incidences, which makes it promising in the applications such as electromagnetic cloaking. PMID:26864084

An Ultra-wideband and Polarization-independent Metasurface for RCS Reduction.

PubMed

Su, Pei; Zhao, Yongjiu; Jia, Shengli; Shi, Wenwen; Wang, Hongli

2016-02-11

In this paper, an ultra-wideband and polarization-independent metasurface for radar cross section (RCS) reduction is proposed. The unit cell of the metasurface operates in a linear cross-polarization scheme in a broad band. The phase and amplitude of cross-polarized reflection can be separately controlled by its geometry and rotation angle. Based on the diffuse reflection theory, a 3-bit coding metasurface is designed to reduce the RCS in an ultra-wide band. The wideband property of the metasurface benefits from the wideband cross polarization conversion and flexible phase modulation. In addition, the polarization-independent feature of the metasurface is achieved by tailoring the rotation angle of each element. Both the simulated and measured results demonstrate that the proposed metasurface can reduce the RCS significantly in an ultra-wide frequency band for both normal and oblique incidences, which makes it promising in the applications such as electromagnetic cloaking.

Terahertz radar cross section measurements.

PubMed

Iwaszczuk, Krzysztof; Heiselberg, Henning; Jepsen, Peter Uhd

2010-12-06

We perform angle- and frequency-resolved radar cross section (RCS) measurements on objects at terahertz frequencies. Our RCS measurements are performed on a scale model aircraft of size 5-10 cm in polar and azimuthal configurations, and correspond closely to RCS measurements with conventional radar on full-size objects. The measurements are performed in a terahertz time-domain system with freely propagating terahertz pulses generated by tilted pulse front excitation of lithium niobate crystals and measured with sub-picosecond time resolution. The application of a time domain system provides ranging information and also allows for identification of scattering points such as weaponry attached to the aircraft. The shapes of the models and positions of reflecting parts are retrieved by the filtered back projection algorithm.

Radar cross section fundamentals for the aircraft designer

NASA Technical Reports Server (NTRS)

Stadmore, H. A.

1979-01-01

Various aspects of radar cross-section (RCS) techniques are summarized, with emphasis placed on fundamental electromagnetic phenomena, such as plane and spherical wave formulations, and the definition of RCS is given in the far-field sense. The basic relationship between electronic countermeasures and a signature level is discussed in terms of the detectability range of a target vehicle. Fundamental radar-signature analysis techniques, such as the physical-optics and geometrical-optics approximations, are presented along with examples in terms of aircraft components. Methods of analysis based on the geometrical theory of diffraction are considered and various wave-propagation phenomena are related to local vehicle geometry. Typical vehicle components are also discussed, together with their contribution to total vehicle RCS and their individual signature sensitivities.

Broadband Polarization Conversion Metasurface Based on Metal Cut-Wire Structure for Radar Cross Section Reduction.

PubMed

Yang, Jia Ji; Cheng, Yong Zhi; Ge, Chen Chen; Gong, Rong Zhou

2018-04-19

A class of linear polarization conversion coding metasurfaces (MSs) based on a metal cut-wire structure is proposed, which can be applied to the reduction properties of radar cross section (RCS). We firstly present a hypothesis based on the principle of planar array theory, and then verify the RCS reduction characteristics using linear polarization conversion coding MSs by simulations and experiments. The simulated results show that in the frequency range of 6⁻14 GHz, the linear polarization conversion ratio reaches a maximum value of 90%, which is in good agreement with the theoretical predictions. For normal incident x - and y -polarized waves, RCS reduction of designed coding MSs 01/01 and 01/10 is essentially more than 10 dB in the above-mentioned frequency range. We prepare and measure the 01/10 coding MS sample, and find that the experimental results in terms of reflectance and RCS reduction are in good agreement with the simulated ones under normal incidence. In addition, under oblique incidence, RCS reduction is suppressed as the angle of incidence increases, but still exhibits RCS reduction effects in a certain frequency range. The designed MS is expected to have valuable potential in applications for stealth field technology.

Effect of radar frequency on the detection of shaped (low RCS) targets

NASA Astrophysics Data System (ADS)

Moraitis, D.; Alland, S.

The use of shaping to reduce the radar cross-section (RCS) of aircraft and missiles can result in the RCS varying significantly with radar operating frequency. This RCS sensitivity to frequency should be considered when selecting radar frequency and should be accounted for when evaluating radar performance. A detection range increase for shaped (low RCS) targets of a factor of two or greater can be realized for lower frequency radar (e.g., UHF-Band or L-Band) when compared to higher frequency radar (C-Band or X-Band). For low flying (sea skimming) targets, the RCS variation with frequency for shaped (low RCS) targets neutralizes the advantage that higher radar frequencies realize in multipath propagation resulting in approximately the same detection range across the radar bands from UHF to X-Band.

RCS of ships and aircraft at HF frequencies

NASA Astrophysics Data System (ADS)

Trueman, C. W.; Kubina, S. J.; Mishra, S. R.; Larose, C.

Coastal radar operating at high frequency (HF) has the potential of monitoring iceberg movement and ship and aircraft traffic over a wide area of ocean. The HF radar cross-section of an aircraft-like scatterer of simple geometry is investigated. At these frequencies, the aircraft size is comparable to the wavelength. The aircraft radar cross-section (RCS) is obtained both by computation and by direct measurement. It is demonstrated that at low frequencies in the HF range, the dorsal fin is the dominant scatterer, but at high HF the fuselage can scatter more strongly than the dorsal fin. Aircraft often carry wire antennas for HF communication, and it is shown that such wires can dramatically alter the RCS of the aircraft near the resonant frequencies of the wire. The RCS of a ship modelled as a parallelepiped with mast is 20-30 decibels larger than that of an aircraft, and is dominated at low HF by the contribution of the mast.

Relating the microwave radar cross section to the sea surface stress - Physics and algorithms

NASA Technical Reports Server (NTRS)

Weissman, David E.; Plant, William J.; Brown, Robert A.; Davidson, Kenneth L.; Shaw, William J.

1991-01-01

The FASINEX (Frontal Air-Sea Interaction Experiment) provided a unique data set with coincident airborne measurements of the ocean surface radar cross section (at Ku-band) and surface windstress. It is being analyzed to create new algorithms and to better understand the air-sea variables that can have a strong influence on the RCS (radar cross section). Several studies of portions of data from the FASINEX indicate that the RCS is more dependent on the surface stress than on the wind speed. Radar data have been acquired by the JPL and NRL groups. The data span 12 different flight days. Stress measurements can be inferred from ship-board instruments and from aircraft closely following the scatterometers.

Simulation on change of generic satellite radar cross section via artificially created plasma sprays

NASA Astrophysics Data System (ADS)

Chung, Shen Shou Max; Chuang, Yu-Chou

2016-06-01

Recent advancements in antisatellite missile technologies have proven the effectiveness of such attacks, and the vulnerability of satellites in such exercises inspires a new paradigm in RF Stealth techniques suitable for satellites. In this paper we examine the possibility of using artificially created plasma sprays on the surface of the satellite’s main body to alter its radar cross section (RCS). First, we briefly review past research related to RF Stealth using plasma. Next, we discuss the physics between electromagnetic waves and plasma, and the RCS number game in RF Stealth design. A comparison of RCS in a generic satellite and a more complicated model is made to illustrate the effect of the RCS number game, and its meaning for a simulation model. We also run a comparison between finite-difference-time-domain (FDTD) and multilevel fast multipole method (MLFMM) codes, and find the RCS results are very close. We then compare the RCS of the generic satellite and the plasma-covered satellite. The incident radar wave is a differentiated Gaussian monopulse, with 3 dB bandwidth between 1.2 GHz and 4 GHz, and we simulate three kinds of plasma density, with a characteristic plasma frequency ω P  =  0.1, 1, and 10 GHz. The electron-neutral collision frequency ν en is set at 0.01 GHz. We found the RCS of plasma-covered satellite is not necessarily smaller than the originally satellite. When ω P is 0.1 GHz, the plasma spray behaves like a dielectric, and there is minor reduction in the RCS. When ω P is 1 GHz, the X-Y cut RCS increases. When ω P is 10 GHz, the plasma behaves more like a metal to the radar wave, and stronger RCS dependency to frequency appears. Therefore, to use plasma as an RCS adjustment tool requires careful fine-tuning of plasma density and shape, in order to achieve the so-called plasma stealth effect.

Radar-cross-section reduction of wind turbines. part 1.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brock, Billy C.; Loui, Hung; McDonald, Jacob J.

2012-03-05

In recent years, increasing deployment of large wind-turbine farms has become an issue of growing concern for the radar community. The large radar cross section (RCS) presented by wind turbines interferes with radar operation, and the Doppler shift caused by blade rotation causes problems identifying and tracking moving targets. Each new wind-turbine farm installation must be carefully evaluated for potential disruption of radar operation for air defense, air traffic control, weather sensing, and other applications. Several approaches currently exist to minimize conflict between wind-turbine farms and radar installations, including procedural adjustments, radar upgrades, and proper choice of low-impact wind-farm sites,more » but each has problems with limited effectiveness or prohibitive cost. An alternative approach, heretofore not technically feasible, is to reduce the RCS of wind turbines to the extent that they can be installed near existing radar installations. This report summarizes efforts to reduce wind-turbine RCS, with a particular emphasis on the blades. The report begins with a survey of the wind-turbine RCS-reduction literature to establish a baseline for comparison. The following topics are then addressed: electromagnetic model development and validation, novel material development, integration into wind-turbine fabrication processes, integrated-absorber design, and wind-turbine RCS modeling. Related topics of interest, including alternative mitigation techniques (procedural, at-the-radar, etc.), an introduction to RCS and electromagnetic scattering, and RCS-reduction modeling techniques, can be found in a previous report.« less

RCS of resonant scatterers with attached wires

NASA Astrophysics Data System (ADS)

Trueman, C. W.; Mishra, S. R.; Kubina, S. J.; Larose, C. L.

1993-03-01

Some aircraft carry wire antennas for HF communication. This paper investigates the effect of such wires on the radar cross section (RCS) at HF frequencies by comparing the RCS of a strip, a cylinder, and a rod with and without an attached wire. The RCS is found for broadside incidence and for end-on incidence of the plane wave for scatterer lengths from 0.4 to 3.8 wavelengths, typical of aircraft size at HF frequencies. It is shown that the RCS of such fuselage-like targets with a wire 'antenna' is quite different from that of the targets without the wire. For broadside incidence, the wire contributes a sharp peak-and-trough to the RCS at the wire's fundamental resonant frequency. For end-on incidence the wire considerably enhances the RCS at frequencies making its length odd multiples of the quarter-wave.

Conformal fractal antenna and FSS for low-RCS applications

NASA Astrophysics Data System (ADS)

Varadan, Vijay K.; Vinoy, K. J.; Jose, K. A.; Varadan, Vasundara V.

2000-06-01

On many situations the reduction of radar cross section (RCS) is of continued strategic interest, especially with aircraft and missiles. Once the overall RCS of the vehicle is reduced, the reflections from the antennas can dominate. The commonly known approaches to RCS reduction may not be applicable for antennas, and hence special techniques are followed. These include configuring the antennas completely conformal, and using band pass frequency selective surfaces. The use fractal patterns have shown to result in such band pass characteristics. The overall RCS of a typical target body is experimentally found to be reduced when these screens are used. The paper presents the experimental result on the transmission and backscatter characteristics of a fractal FSS screen.

Planar near-field scanning for compact range bistatic radar cross-section measurement. Thesis Final Report

NASA Technical Reports Server (NTRS)

Tuhela-Reuning, S. R.; Walton, E. K.

1991-01-01

The design, construction, and testing of a low cost, planar scanning system to be used in a compact range environment for bistatic radar cross-section (bistatic RCS) measurement data are discussed. This scanning system is similar to structures used for measuring near-field antenna patterns. A synthetic aperture technique is used for plane wave reception. System testing entailed comparison of measured and theoretical bistatic RCS of a sphere and a right circular cylinder. Bistatic scattering analysis of the ogival target support, target and pedestal interactions, and compact range room was necessary to determine measurement validity.

Broadband and wide-angle RCS reduction using a 2-bit coding ultrathin metasurface at terahertz frequencies

PubMed Central

Liang, Lanju; Wei, Minggui; Yan, Xin; Wei, Dequan; Liang, Dachuan; Han, Jiaguang; Ding, Xin; Zhang, GaoYa; Yao, Jianquan

2016-01-01

A novel broadband and wide-angle 2-bit coding metasurface for radar cross section (RCS) reduction is proposed and characterized at terahertz (THz) frequencies. The ultrathin metasurface is composed of four digital elements based on a metallic double cross line structure. The reflection phase difference of neighboring elements is approximately 90° over a broadband THz frequency. The mechanism of RCS reduction is achieved by optimizing the coding element sequences, which redirects the electromagnetic energies to all directions in broad frequencies. An RCS reduction of less than −10 dB bandwidth from 0.7 THz to 1.3 THz is achieved in the experimental and numerical simulations. The simulation results also show that broadband RCS reduction can be achieved at an incident angle below 60° for TE and TM polarizations under flat and curve coding metasurfaces. These results open a new approach to flexibly control THz waves and may offer widespread applications for novel THz devices. PMID:27982089

Broadband and wide-angle RCS reduction using a 2-bit coding ultrathin metasurface at terahertz frequencies.

PubMed

Liang, Lanju; Wei, Minggui; Yan, Xin; Wei, Dequan; Liang, Dachuan; Han, Jiaguang; Ding, Xin; Zhang, GaoYa; Yao, Jianquan

2016-12-16

A novel broadband and wide-angle 2-bit coding metasurface for radar cross section (RCS) reduction is proposed and characterized at terahertz (THz) frequencies. The ultrathin metasurface is composed of four digital elements based on a metallic double cross line structure. The reflection phase difference of neighboring elements is approximately 90° over a broadband THz frequency. The mechanism of RCS reduction is achieved by optimizing the coding element sequences, which redirects the electromagnetic energies to all directions in broad frequencies. An RCS reduction of less than -10 dB bandwidth from 0.7 THz to 1.3 THz is achieved in the experimental and numerical simulations. The simulation results also show that broadband RCS reduction can be achieved at an incident angle below 60° for TE and TM polarizations under flat and curve coding metasurfaces. These results open a new approach to flexibly control THz waves and may offer widespread applications for novel THz devices.

Joint passive radar tracking and target classification using radar cross section

NASA Astrophysics Data System (ADS)

Herman, Shawn M.

2004-01-01

We present a recursive Bayesian solution for the problem of joint tracking and classification of airborne targets. In our system, we allow for complications due to multiple targets, false alarms, and missed detections. More importantly, though, we utilize the full benefit of a joint approach by implementing our tracker using an aerodynamically valid flight model that requires aircraft-specific coefficients such as wing area and vehicle mass, which are provided by our classifier. A key feature that bridges the gap between tracking and classification is radar cross section (RCS). By modeling the true deterministic relationship that exists between RCS and target aspect, we are able to gain both valuable class information and an estimate of target orientation. However, the lack of a closed-form relationship between RCS and target aspect prevents us from using the Kalman filter or its variants. Instead, we rely upon a sequential Monte Carlo-based approach known as particle filtering. In addition to allowing us to include RCS as a measurement, the particle filter also simplifies the implementation of our nonlinear non-Gaussian flight model.

Joint passive radar tracking and target classification using radar cross section

NASA Astrophysics Data System (ADS)

Herman, Shawn M.

2003-12-01

We present a recursive Bayesian solution for the problem of joint tracking and classification of airborne targets. In our system, we allow for complications due to multiple targets, false alarms, and missed detections. More importantly, though, we utilize the full benefit of a joint approach by implementing our tracker using an aerodynamically valid flight model that requires aircraft-specific coefficients such as wing area and vehicle mass, which are provided by our classifier. A key feature that bridges the gap between tracking and classification is radar cross section (RCS). By modeling the true deterministic relationship that exists between RCS and target aspect, we are able to gain both valuable class information and an estimate of target orientation. However, the lack of a closed-form relationship between RCS and target aspect prevents us from using the Kalman filter or its variants. Instead, we rely upon a sequential Monte Carlo-based approach known as particle filtering. In addition to allowing us to include RCS as a measurement, the particle filter also simplifies the implementation of our nonlinear non-Gaussian flight model.

Plasma distributions in meteor head echoes and implications for radar cross section interpretation

NASA Astrophysics Data System (ADS)

Marshall, Robert A.; Brown, Peter; Close, Sigrid

2017-09-01

The derivation of meteoroid masses from radar measurements requires conversion of the measured radar cross section (RCS) to meteoroid mass. Typically, this conversion passes first through an estimate of the meteor plasma density derived from the RCS. However, the conversion from RCS to meteor plasma density requires assumptions on the radial electron density distribution. We use simultaneous triple-frequency measurements of the RCS for 63 large meteor head echoes to derive estimates of the meteor plasma size and density using five different possible radial electron density distributions. By fitting these distributions to the observed meteor RCS values and estimating the goodness-of-fit, we determine that the best fit to the data is a 1 /r2 plasma distribution, i.e. the electron density decays as 1 /r2 from the center of the meteor plasma. Next, we use the derived plasma distributions to estimate the electron line density q for each meteor using each of the five distributions. We show that depending on the choice of distribution, the line density can vary by a factor of three or more. We thus argue that a best estimate for the radial plasma distribution in a meteor head echo is necessary in order to have any confidence in derived meteoroid masses.

Absorptive coding metasurface for further radar cross section reduction

NASA Astrophysics Data System (ADS)

Sui, Sai; Ma, Hua; Wang, Jiafu; Pang, Yongqiang; Feng, Mingde; Xu, Zhuo; Qu, Shaobo

2018-02-01

Lossless coding metasurfaces and metamaterial absorbers have been widely used for radar cross section (RCS) reduction and stealth applications, which merely depend on redirecting electromagnetic wave energy into various oblique angles or absorbing electromagnetic energy, respectively. Here, an absorptive coding metasurface capable of both the flexible manipulation of backward scattering and further wideband bistatic RCS reduction is proposed. The original idea is carried out by utilizing absorptive elements, such as metamaterial absorbers, to establish a coding metasurface. We establish an analytical connection between an arbitrary absorptive coding metasurface arrangement of both the amplitude and phase and its far-field pattern. Then, as an example, an absorptive coding metasurface is demonstrated as a nonperiodic metamaterial absorber, which indicates an expected better performance of RCS reduction than the traditional lossless coding metasurface and periodic metamaterial-absorber. Both theoretical analysis and full-wave simulation results show good accordance with the experiment.

Scientific visualization of volumetric radar cross section data

NASA Astrophysics Data System (ADS)

Wojszynski, Thomas G.

1992-12-01

For aircraft design and mission planning, designers, threat analysts, mission planners, and pilots require a Radar Cross Section (RCS) central tendency with its associated distribution about a specified aspect and its relation to a known threat, Historically, RCS data sets have been statically analyzed to evaluate a d profile. However, Scientific Visualization, the application of computer graphics techniques to produce pictures of complex physical phenomena appears to be a more promising tool to interpret this data. This work describes data reduction techniques and a surface rendering algorithm to construct and display a complex polyhedron from adjacent contours of RCS data. Data reduction is accomplished by sectorizing the data and characterizing the statistical properties of the data. Color, lighting, and orientation cues are added to complete the visualization system. The tool may be useful for synthesis, design, and analysis of complex, low observable air vehicles.

Intensive Care Research Coordinators in Australia and New Zealand: a cross-sectional survey of demographics, responsibilities, job satisfaction and importance.

PubMed

Roberts, Brigit; Eastwood, Glenn M; Raunow, Heike; Howe, Belinda; Rickard, Claire M

2011-11-01

The achievement of successful clinical research projects depends on multiple team members including Research Coordinators (RCs), who are the link between the researcher and the trial participants. The RCs main responsibility is to ensure that all research is conducted according to the appropriate protocols, regulations and guidelines. Description of demographics, the role and associated responsibilities and assessment of items of importance to, and satisfaction with, various job related items. An observational web-based cross-sectional study of RCs working in Intensive Care Units (ICU) across Australia and New Zealand. Fifty-six participants completed the survey. Forty percent had more than 6 years experience in ICU research and one-third held a Masters Degree. Most respondents performed research related tasks including ethics submission, patient screening, education and data collection. Autonomy and work hours were the most satisfying job characteristics reported and aspects relating to autonomy were most important for the RCs. Inadequate remuneration was of great concern to the participants. Research Coordinators in Australia and New Zealand have many and varied roles with a significant workload. Unfortunately, the RCs do not feel their employers are adequately remunerating the demand on their time and efforts. The results indicate that RCs enjoy high levels of satisfaction with general conditions and facets of their work and its environment and they remain passionate about their role in the ICU setting. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Radar cross-section reduction based on an iterative fast Fourier transform optimized metasurface

NASA Astrophysics Data System (ADS)

Song, Yi-Chuan; Ding, Jun; Guo, Chen-Jiang; Ren, Yu-Hui; Zhang, Jia-Kai

2016-07-01

A novel polarization insensitive metasurface with over 25 dB monostatic radar cross-section (RCS) reduction is introduced. The proposed metasurface is comprised of carefully arranged unit cells with spatially varied dimension, which enables approximate uniform diffusion of incoming electromagnetic (EM) energy and reduces the threat from bistatic radar system. An iterative fast Fourier transform (FFT) method for conventional antenna array pattern synthesis is innovatively applied to find the best unit cell geometry parameter arrangement. Finally, a metasurface sample is fabricated and tested to validate RCS reduction behavior predicted by full wave simulation software Ansys HFSSTM and marvelous agreement is observed.

Measurement of Automobile UWB Radar Cross Sections at Ka Band

NASA Astrophysics Data System (ADS)

Kobayashi, Takehiko; Takahashi, Naoto; Yoshikawa, Makoto; Tsunoda, Kikuo; Tenno, Nobuyuki

Ultra-wideband (UWB) radar cross sections (RCS) of an automobile were measured in the frequency range from 22 to 29 GHz, with a view to obtaining information on the design of vehicular cruise control short-range radars. The measurements were made in a radio anechoic chamber using three transmitting and receiving polarization combinations (V-V, H-H, and +45° to -45°). A vector network analyzer was used in making the wideband measurements. The UWB RCSs were derived by integrating the receiving power from 22 to 29 GHz. It was found that the UWB RCS of the automobile varied as follows:

Wideband radar cross section reduction using two-dimensional phase gradient metasurfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yongfeng; Qu, Shaobo; Wang, Jiafu

2014-06-02

Phase gradient metasurface (PGMs) are artificial surfaces that can provide pre-defined in-plane wave-vectors to manipulate the directions of refracted/reflected waves. In this Letter, we propose to achieve wideband radar cross section (RCS) reduction using two-dimensional (2D) PGMs. A 2D PGM was designed using a square combination of 49 split-ring sub-unit cells. The PGM can provide additional wave-vectors along the two in-plane directions simultaneously, leading to either surface wave conversion, deflected reflection, or diffuse reflection. Both the simulation and experiment results verified the wide-band, polarization-independent, high-efficiency RCS reduction induced by the 2D PGM.

The relationship between the microwave radar cross section and both wind speed and stress: Model function studies using Frontal Air-Sea Interaction Experiment data

NASA Astrophysics Data System (ADS)

Weissman, David E.; Davidson, Kenneth L.; Brown, Robert A.; Friehe, Carl A.; Li, Fuk

1994-05-01

The Frontal Air-Sea Interaction Experiment (FASINEX) provided a unique data set with coincident airborne scatterometer measurements of the ocean surface radar cross section (RCS) (at Ku band) and near-surface wind and wind stress. These data have been analyzed to study new model functions which relate wind speed and surface friction velocity (square root of the kinematic wind stress) to the radar cross section and to better understand the processes in the boundary layer that have a strong influence on the radar backscatter. Studies of data from FASINEX indicate that the RCS has a different relation to the friction velocity than to the wind speed. The difference between the RCS models using these two variables depends on the polarization and the incidence angle. The radar data have been acquired from the Jet Propulsion Laboratory airborne scatterometer. These data span 10 different flight days. Stress measurements were inferred from shipboard instruments and from aircraft flying at low altitudes, closely following the scatterometer. Wide ranges of radar incidence angles and environmental conditions needed to fully develop algorithms are available from this experiment.

The relationship between the microwave radar cross section and both wind speed and stress: Model function studies using Frontal Air-Sea Interaction Experiment data

NASA Technical Reports Server (NTRS)

Weissman, David E.; Davidson, Kenneth L.; Brown, Robert A.; Friehe, Carl A.; Li, Fuk

1994-01-01

The Frontal Air-Sea Interaction Experiment (FASINEX) provided a unique data set with coincident airborne scatterometer measurements of the ocean surface radar cross section (RCS)(at Ku band) and near-surface wind and wind stress. These data have been analyzed to study new model functions which relate wind speed and surface friction velocity (square root of the kinematic wind stress) to the radar cross section and to better understand the processes in the boundary layer that have a strong influence on the radar backscatter. Studies of data from FASINEX indicate that the RCS has a different relation to the friction velocity than to the wind speed. The difference between the RCS models using these two variables depends on the polarization and the incidence angle. The radar data have been acquired from the Jet Propulsion Laboratory airborne scatterometer. These data span 10 different flight days. Stress measurements were inferred from shipboard instruments and from aircraft flying at low altitudes, closely following the scatterometer. Wide ranges of radar incidence angles and environmental conditions needed to fully develop algorithms are available from this experiment.

Random Combinatorial Gradient Metasurface for Broadband, Wide-Angle and Polarization-Independent Diffusion Scattering.

PubMed

Zhuang, Yaqiang; Wang, Guangming; Liang, Jiangang; Cai, Tong; Tang, Xiao-Lan; Guo, Tongfeng; Zhang, Qingfeng

2017-11-29

This paper proposes an easy, efficient strategy for designing broadband, wide-angle and polarization-independent diffusion metasurface for radar cross section (RCS) reduction. A dual-resonance unit cell, composed of a cross wire and cross loop (CWCL), is employed to enhance the phase bandwidth covering the 2π range. Both oblique-gradient and horizontal-gradient phase supercells are designed for illustration. The numerical results agree well with the theoretical ones. To significantly reduce backward scattering, the random combinatorial gradient metasurface (RCGM) is subsequently constructed by collecting eight supercells with randomly distributed gradient directions. The proposed metasurface features an enhanced specular RCS reduction performance and less design complexity compared to other candidates. Both simulated and measured results show that the proposed RCGM can significantly suppress RCS and exhibits broadband, wide-angle and polarization independence features.

An experimental study of microwave scattering from rain- and wind-roughened seas

NASA Technical Reports Server (NTRS)

Bliven, L. F.; Giovanangeli, J.-P.

1993-01-01

This paper investigates radar cross-section (RCS) characteristics of rain- and wind-roughened sea-surfaces. We conducted experiments in laboratory wind-wave tanks using artificial rain. The study includes light rain rates, light wind speeds, and combinations of these. A 36 Ghz scatterometer was operated at 30 deg incidence angle and with vertical polarization. RCS data were obtained not only with the scatterometer pointing up-wind but also as a function of azimuthal angle. We use a scatterometer rain and wind model SRWM-1, which relates the total average RCS in storms to the sum of the average RCS due to rain plus the average RCS due to wind. Implications of the study for operational monitoring of wind in rainy oceanic areas by satellite-borne instruments is discussed.

Scattering of E Polarized Plane Wave by Rectangular Cavity With Finite Flanges

NASA Astrophysics Data System (ADS)

Vinogradova, Elena D.

2017-11-01

The rigorous Method of Regularization is implemented for accurate analysis of wave scattering by rectangular cavity with finite flanges. The solution is free from limitations on problem parameters. The calculation of the induced surface current, bistatic radar cross section (RCS) and frequency dependence of monostatic RCS are performed with controlled accuracy in a wide frequency band.

Reduction of the radar cross section of arbitrarily shaped cavity structures

NASA Technical Reports Server (NTRS)

Chou, R.; Ling, H.; Lee, S. W.

1987-01-01

The problem of the reduction of the radar cross section (RCS) of open-ended cavities was studied. The issues investigated were reduction through lossy coating materials on the inner cavity wall and reduction through shaping of the cavity. A method was presented to calculate the RCS of any arbitrarily shaped structure in order to study the shaping problem. The limitations of this method were also addressed. The modal attenuation was studied in a multilayered coated waveguide. It was shown that by employing two layers of coating, it was possible to achieve an increase in both the magnitude of attenuation and the frequency band of effectiveness. The numerical method used in finding the roots of the characteristic equation breaks down when the coating thickness is very lossy and large in terms of wavelength. A new method of computing the RCS of an arbitrary cavity was applied to study the effects of longitudinal bending on RCS reduction. The ray and modal descriptions for the fields in a parallel plate waveguide were compared. To extend the range of validity of the Shooting and Bouncing Ray (SBR) method, the simple ray picture must be modified to account for the beam blurring.

A study of different fabrics to increase radar cross section of humans.

PubMed

Ödman, Torbjörn; Welinder, Jan; Andersson, Nils; Otterskog, Magnus; Lindén, Maria; Ödman, Natalia; Larsson, Christer

2015-01-01

This purpose of the study was to increase the visibility on radar for unprotected pedestrians with the aid of conducting fabric. The experiment comprised measurements of four types of fabric to determine the radio frequency properties, such as radar cross section (RCS) for the vehicle radar frequency 77 GHz and transmission (shielding) in the frequency range 3-18 GHz. Two different thicknesses of polypyrrole (PPy) nonvowen fabric were tested and one thickness for 30 % and 40 % stainless steel fabrics respectively. A jacket with the thinner nonvowen material and one with 40 % steel were tested and compared to an unmodified jacket in the RCS measurement. The measurement showed an increase in RCS of 4 dB for the jacket with the 40 % steel lining compared to the unmodified jacket. The transmission measurement was aimed at determining the fabric with the highest transmission of an incoming radio wave. The 30 % steel fabric and the two thicknesses of the nonvowen fabrics were tested. One practical application is for example the use of radar reflective material in search and rescue (SAR) clothes. The study showed that the 30 % steel fabric was the best candidate for further RCS measurements.

A modal radar cross section of thin-wire targets via the singularity expansion method

NASA Technical Reports Server (NTRS)

Richards, M. A.; Shumpert, T. H.; Riggs, L. S.

1992-01-01

A modal radar cross section (RCS) of arbitrary wire scatterers is constructed in terms of SEM parameters. Numerical results are presented for both straight and L-shaped wire targets and are compared to computations performed in the frequency domain using the method of moments.

An Accurate Method for Measuring Airplane-Borne Conformal Antenna's Radar Cross Section

NASA Astrophysics Data System (ADS)

Guo, Shuxia; Zhang, Lei; Wang, Yafeng; Hu, Chufeng

2016-09-01

The airplane-borne conformal antenna attaches itself tightly with the airplane skin, so the conventional measurement method cannot determine the contribution of the airplane-borne conformal antenna to its radar cross section (RCS). This paper uses the 2D microwave imaging to isolate and extract the distribution of the reflectivity of the airplane-borne conformal antenna. It obtains the 2D spatial spectra of the conformal antenna through the wave spectral transform between the 2D spatial image and the 2D spatial spectrum. After the interpolation from the rectangular coordinate domain to the polar coordinate domain, the spectral domain data for the variation of the scatter of the conformal antenna with frequency and angle is obtained. The experimental results show that the measurement method proposed in this paper greatly enhances the airplane-borne conformal antenna's RCS measurement accuracy, essentially eliminates the influences caused by the airplane skin and more accurately reveals the airplane-borne conformal antenna's RCS scatter properties.

Laser backscattered from partially convex targets of large sizes in random media for E-wave polarization.

PubMed

El-Ocla, Hosam

2006-08-01

The characteristics of a radar cross section (RCS) of partially convex targets with large sizes up to five wavelengths in free space and random media are studied. The nature of the incident wave is an important factor in remote sensing and radar detection applications. I investigate the effects of beam wave incidence on the performance of RCS, drawing on the method I used in a previous study on plane-wave incidence. A beam wave can be considered a plane wave if the target size is smaller than the beam width. Therefore, to have a beam wave with a limited spot on the target, the target size should be larger than the beam width (assuming E-wave incidence wave polarization. The effects of the target configuration, random medium parameters, and the beam width on the laser RCS and the enhancement in the radar cross section are numerically analyzed, resulting in the possibility of having some sort of control over radar detection using beam wave incidence.

Radar targets reveal all to automated tester

NASA Astrophysics Data System (ADS)

Hartman, R. E.

1985-09-01

Technological developments in the field of automated test equipment for low radar-cross-section (RCS) systems are reviewed. Emphasis is given to an Automated Digital Analysis and Measurement (ADAM) system for measuring, scattering, and evaluating RCS using a minicomputer in combination with a vector network analyzer and a positioner programmer. ADAM incorporates a stepped CW measurement technique to obtain RCS as a function of both range and frequency at a fixed aspect angle. The operating characteristics and calibration procedures of the ADAM system are described and estimates of RCS sensitivity are obtained. The response resolution of the ADAM system is estimated to be 36 cm per measurement bandwidth (in GHz) for a minimum window. A block diagram of the error checking routine of the ADAM system is provided.

Dynamic imaging and RCS measurements of aircraft

NASA Astrophysics Data System (ADS)

Jain, Atul; Patel, Indu

1995-01-01

Results on radar cross section (RCS) measurements and inverse synthetic aperture radar images of a Mooney 231 aircraft using a ground-to-air measurement system (GTAMS) and a KC-135 airplane using an airborne radar are presented. The Mooney 231 flew in a controlled path in both clockwise and counterclockwise orbits, and successively with the gear down, flaps in the take-off position and with the speed brakes up. The data indicates that RCS pattern measurements from both ground-based and airborne radar of flying aircraft are useful and that the inverse synthetic aperture radar (ISAR) images obtained are valuable for signature diagnostics.

Metasurface base on uneven layered fractal elements for ultra-wideband RCS reduction

NASA Astrophysics Data System (ADS)

Su, Jianxun; Cui, Yueyang; Li, Zengrui; Yang, Yaoqing Lamar; Che, Yongxing; Yin, Hongcheng

2018-03-01

A novel metasurface based on uneven layered fractal elements is designed and fabricated for ultra-wideband radar cross section (RCS) reduction in this paper. The proposed metasurface consists of two fractal subwavelength elements with different layer thickness. The reflection phase difference of 180° (±37°) between two unit cells covers an ultra-wide frequency range. Ultra-wideband RCS reduction results from the phase cancellation between two local waves produced by these two unit cells. The diffuse scattering of electromagnetic (EM) waves is caused by the randomized phase distribution, leading to a low monostatic and bistatic RCS simultaneously. This metasurface can achieve -10dB RCS reduction in an ultra-wide frequency range from 6.6 to 23.9 GHz with a ratio bandwidth (fH/fL) of 3.62:1 under normal incidences for both x- and y-polarized waves. Both the simulation and the measurement results are consistent to verify this excellent RCS reduction performance of the proposed metasurface.

Measurements of the radar cross section and Inverse Synthetic Aperture Radar (ISAR) images of a Piper Navajo at 9.5 GHz and 49 GHz

NASA Astrophysics Data System (ADS)

Dinger, R.; Kinzel, G.; Lam, W.; Jones, S.

1993-01-01

Studies were conducted of the enhanced radar cross section (RCS) and improved inverse synthetic aperture radar (ISAR) image quality that may result at millimeter-wave (mmw) frequencies. To study the potential for mmw radar in these areas, a program was initiated in FY-90 to design and fabricate a 49.0- to 49.5-GHz stepped-frequency radar. After conducting simultaneous measurements of the RCS of an airborne Piper Navajo twin-engine aircraft at 9.0 and 49.0 GHz, the RCS at 49.0 GHz was always found to be higher than at 9.0 GHz by an amount that depended on the target aspect angle. The largest increase was 19 dB and was measured at nose-on incidence; at other angles of incidence, the increase ranged from 3 to 10 dB. The increase averaged over a 360-degree aspect-angle change was 7.2 dB. The 49.0-GHz radar has demonstrated a capability to gather well-calibrated millimeter-wave RCS data of flying targets. In addition, the successful ISAR images obtainable with short aperture time suggest that 49.0-GHz radar may have a role to play in noncooperative target identification (NCTI).

MOM3D method of moments code theory manual

NASA Technical Reports Server (NTRS)

Shaeffer, John F.

1992-01-01

MOM3D is a FORTRAN algorithm that solves Maxwell's equations as expressed via the electric field integral equation for the electromagnetic response of open or closed three dimensional surfaces modeled with triangle patches. Two joined triangles (couples) form the vector current unknowns for the surface. Boundary conditions are for perfectly conducting or resistive surfaces. The impedance matrix represents the fundamental electromagnetic interaction of the body with itself. A variety of electromagnetic analysis options are possible once the impedance matrix is computed including backscatter radar cross section (RCS), bistatic RCS, antenna pattern prediction for user specified body voltage excitation ports, RCS image projection showing RCS scattering center locations, surface currents excited on the body as induced by specified plane wave excitation, and near field computation for the electric field on or near the body.

Laboratory Reproduction and Failure Analysis of Cracked Orbiter Reaction Control System Niobium Thruster Injectors

NASA Technical Reports Server (NTRS)

Jacobs, Jeremy B.; Castner, Willard L.

2007-01-01

A viewgraph presentation describing cracks and failure analysis of an orbiter reaction control system is shown. The topics include: 1) Endeavour STS-113 Landing; 2) RCS Thruster; 3) Thruster Cross-Section; 4) RCS Injector; 5) RCS Thruster, S/N 120l 6) Counterbore Cracks; 7) Relief Radius Cracks; 8) RCS Thruster Cracking History; 9) Thruster Manufacturing Timelines; 10) Laboratory Reproduction of Injector Cracking; 11) The Brownfield Specimen; 12) HF EtchantTests/Specimen Loading; 13) Specimen #3 HF + 600F; 14) Specimen #3 IG Fracture; 15) Specimen #5 HF + 600F; 16) Specimen #5 Popcorn ; 17) Specimen #5 Cleaned and Bent; 18) HF Exposure Test Matrix; 19) Krytox143AC Tests; 20) KrytoxTests/Specimen Loading; 21) Specimen #13 Krytox + 600F; and 22) KrytoxExposure Test Matrix.

Current techniques for the real-time processing of complex radar signatures

NASA Astrophysics Data System (ADS)

Clay, E.

A real-time processing technique has been developed for the microwave receiver of the Brahms radar station. The method allows such target signatures as the radar cross section (RCS) of the airframes and rotating parts, the one-dimensional tomography of aircraft, and the RCS of electromagnetic decoys to be characterized. The method allows optimization of experimental parameters including the analysis frequency band, the receiver gain, and the wavelength range of EM analysis.

Effects of respiration depth on human body radar cross section Using 2.4GHz continuous wave radar.

PubMed

Lee, Alexander; Xiaomeng Gao; Jia Xu; Boric-Lubecke, Olga

2017-07-01

In this study, it was tested whether deep and shallow breathing has an effect on the cardiopulmonary radar cross-section (RCS). Continuous wave radar with quadrature architecture at 2.4GHz was used to test 2 human subjects breathing deep and shallow for 30 seconds each while seated 2 meters away from the radar. A retro-reflective marker was placed on the sternum of each subject and measured by infrared motion capture cameras to accurately track displacement of the chest. The quadrature radar outputs were processed to find the radius of the arc on the IQ plot using a circle-fitting algorithm. Results showed that the effective RCS ratio of deep to shallow breathing for subjects 1 and 2 was 6.99 and 2.24 respectively.

High frequency estimation of 2-dimensional cavity scattering

NASA Astrophysics Data System (ADS)

Dering, R. S.

1984-12-01

This thesis develops a simple ray tracing approximation for the high frequency scattering from a two-dimensional cavity. Whereas many other cavity scattering algorithms are very time consuming, this method is very swift. The analytical development of the ray tracing approach is performed in great detail, and it is shown how the radar cross section (RCS) depends on the cavity's length and width along with the radar wave's angle of incidence. This explains why the cavity's RCS oscillates as a function of incident angle. The RCS of a two dimensional cavity was measured experimentally, and these results were compared to computer calculations based on the high frequency ray tracing theory. The comparison was favorable in the sense that angular RCS minima and maxima were exactly predicted even though accuracy of the RCS magnitude decreased for incident angles far off-axis. Overall, once this method is extended to three dimensions, the technique shows promise as a fast first approximation of high frequency cavity scattering.

Numeric Computation of the Radar Cross Section of In-flight Projectiles

DTIC Science & Technology

2016-11-01

SUBJECT TERMS computational electromagnetics , radar signature, ballistic trajectory, radar cross section, RCS 16. SECURITY CLASSIFICATION OF: 17...under the generic category of rockets, artillery, and mortar (RAM). The electromagnetic (EM) modeling team at the US Army Research Laboratory (ARL) is...ARL-TR-5145. 5. Balanis C. Advanced engineering electromagnetics . New York (NY): Wiley; 1989. 6. Ruck G, Barrick DE, Stuart WD, Krichbaum CK

Reduction of the RCS of the leading edge of a conducting wing-shaped structure by means of lossless dielectric material

NASA Astrophysics Data System (ADS)

Booysen, A. J.; Pistorius, C. W. I.; Malherbe, J. A. G.

1991-06-01

The radar cross section of the leading edge of a conducting wing-shaped structure is reduced by replacing part of the structure with a lossless dielectric material. The structure retains its original external shape, thereby ensuring that the aerodynamic properties are not altered by the structural changes needed to reduce the radar cross section.

A closed form, physical optics expression for the radar cross section of a perfectly conducting flat plate over a dielectric half-space

NASA Astrophysics Data System (ADS)

Anastassiu, Hristos T.

2003-04-01

The physical optics approximation is employed in the derivation of a closed form expression for the radar cross section (RCS) of a flat, perfectly conducting plate of various shapes, located over a dielectric, possibly lossy half-space. The half-space is assumed to lie in the far field region of the plate. The well-known "four-path model" is invoked in a first-order approximation of the half-space contribution to the scattering mechanisms. Numerical results are compared to a reference, Moment Method solution, and the agreement is investigated, to assess the accuracy of the approximations used. The analytical expressions derived can facilitate very fast RCS calculations for realistic scatterers, such as ships in a sea environment, or aircraft flying low over the ground.

Application of AWE for RCS Frequency Response Calculations Using Method of Moments

NASA Technical Reports Server (NTRS)

Reddy, C. J.; Deshpande, M. D.

1996-01-01

An implementation of the Asymptotic Waveform Evaluation (AWE) technique is presented for obtaining the frequency response of the Radar Cross Section (RCS) of arbitrarily shaped, three-dimensional perfect electric conductor (PEC) bodies. An Electric Field Integral Equation (EFIE) is solved using the Method of Moments (MoM) to compute the RCS. The electric current, thus obtained, is expanded in a Taylor series around the frequency of interest. The coefficients of the Taylor series (called 'moments') are obtained using the frequency derivatives of the EFIE. Using the moments, the electric current on the PEC body is obtained over a frequency band. Using the electric current at different frequencies, RCS of the PEC body is obtained over a wide frequency band. Numerical results for a square plate, a cube, and a sphere are presented over a bandwidth. A good agreement between AWE and the exact solution over the bandwidth is observed.

Method and apparatus for sensor fusion

NASA Technical Reports Server (NTRS)

Krishen, Kumar (Inventor); Shaw, Scott (Inventor); Defigueiredo, Rui J. P. (Inventor)

1991-01-01

Method and apparatus for fusion of data from optical and radar sensors by error minimization procedure is presented. The method was applied to the problem of shape reconstruction of an unknown surface at a distance. The method involves deriving an incomplete surface model from an optical sensor. The unknown characteristics of the surface are represented by some parameter. The correct value of the parameter is computed by iteratively generating theoretical predictions of the radar cross sections (RCS) of the surface, comparing the predicted and the observed values for the RCS, and improving the surface model from results of the comparison. Theoretical RCS may be computed from the surface model in several ways. One RCS prediction technique is the method of moments. The method of moments can be applied to an unknown surface only if some shape information is available from an independent source. The optical image provides the independent information.

Application of Model Based Parameter Estimation for RCS Frequency Response Calculations Using Method of Moments

NASA Technical Reports Server (NTRS)

Reddy, C. J.

1998-01-01

An implementation of the Model Based Parameter Estimation (MBPE) technique is presented for obtaining the frequency response of the Radar Cross Section (RCS) of arbitrarily shaped, three-dimensional perfect electric conductor (PEC) bodies. An Electric Field Integral Equation (EFTE) is solved using the Method of Moments (MoM) to compute the RCS. The electric current is expanded in a rational function and the coefficients of the rational function are obtained using the frequency derivatives of the EFIE. Using the rational function, the electric current on the PEC body is obtained over a frequency band. Using the electric current at different frequencies, RCS of the PEC body is obtained over a wide frequency band. Numerical results for a square plate, a cube, and a sphere are presented over a bandwidth. Good agreement between MBPE and the exact solution over the bandwidth is observed.

An efficient hybrid technique in RCS predictions of complex targets at high frequencies

NASA Astrophysics Data System (ADS)

Algar, María-Jesús; Lozano, Lorena; Moreno, Javier; González, Iván; Cátedra, Felipe

2017-09-01

Most computer codes in Radar Cross Section (RCS) prediction use Physical Optics (PO) and Physical theory of Diffraction (PTD) combined with Geometrical Optics (GO) and Geometrical Theory of Diffraction (GTD). The latter approaches are computationally cheaper and much more accurate for curved surfaces, but not applicable for the computation of the RCS of all surfaces of a complex object due to the presence of caustic problems in the analysis of concave surfaces or flat surfaces in the far field. The main contribution of this paper is the development of a hybrid method based on a new combination of two asymptotic techniques: GTD and PO, considering the advantages and avoiding the disadvantages of each of them. A very efficient and accurate method to analyze the RCS of complex structures at high frequencies is obtained with the new combination. The proposed new method has been validated comparing RCS results obtained for some simple cases using the proposed approach and RCS using the rigorous technique of Method of Moments (MoM). Some complex cases have been examined at high frequencies contrasting the results with PO. This study shows the accuracy and the efficiency of the hybrid method and its suitability for the computation of the RCS at really large and complex targets at high frequencies.

Backscatter RCS for TE and TM excitations of dielectric-filled cavity-backed apertures in two-dimensional bodies

NASA Technical Reports Server (NTRS)

Goggans, Paul M.; Shumpert, Thomas H.

1991-01-01

Transverse electric (TE) and transverse magnetic (TM) scattering from dielectric-filled, cavity-backed apertures in two-dimensional bodies are treated using the method of moments technique to solve a set of combined-field integral equations for the equivalent induced electric and magnetic currents on the exterior of the scattering body and on the associated aperture. Results are presented for the backscatter radar cross section (RCS) versus the electrical size of the scatterer for two different dielectric-filled cavity-backed geometries. The first geometry is a circular cylinder of infinite length which has an infinite length slot aperture along one side. The cavity inside the cylinder is dielectric filled and is also of circular cross section. The two cylinders (external and internal) are of different radii and their respective longitudinal axes are parallel but not collocated. The second is a square cylinder of infinite length which has an infinite length slot aperture along one side. The cavity inside the square cylinder is dielectric-filled and is also of square cross section.

RCS Diversity of Electromagnetic Wave Carrying Orbital Angular Momentum.

PubMed

Zhang, Chao; Chen, Dong; Jiang, Xuefeng

2017-11-13

An electromagnetic (EM) wave with orbital angular momentum (OAM) has a helical wave front, which is different from that of the plane wave. The phase gradient can be found perpendicular to the direction of propagation and proportional to the number of OAM modes. Herein, we study the backscattering property of the EM wave with different OAM modes, i.e., the radar cross section (RCS) of the target is measured and evaluated with different OAM waves. As indicated by the experimental results, different OAM waves have the same RCS fluctuation for the simple target, e.g., a small metal ball as the target. However, for complicated targets, e.g., two transverse-deployed small metal balls, different RCSs can be identified from the same incident angle. This valuable fact helps to obtain RCS diversity, e.g., equal gain or selective combining of different OAM wave scattering. The majority of the targets are complicated targets or expanded targets; the RCS diversity can be utilized to detect a weak target traditionally measured by the plane wave, which is very helpful for anti-stealth radar to detect the traditional stealth target by increasing the RCS with OAM waves.

Numerical RCS and micro-Doppler investigations of a consumer UAV

NASA Astrophysics Data System (ADS)

Schröder, Arne; Aulenbacher, Uwe; Renker, Matthias; Böniger, Urs; Oechslin, Roland; Murk, Axel; Wellig, Peter

2016-10-01

This contribution gives an overview of recent investigations regarding the detection of a consumer market unmanned aerial vehicles (UAV). The steadily increasing number of such drones gives rise to the threat of UAVs interfering civil air traffic. Technologies for monitoring UAVs which are flying in restricted air space, i. e. close to airports or even over airports, are desperately needed. One promising way for tracking drones is to employ radar systems. For the detection and classification of UAVs, the knowledge about their radar cross section (RCS) and micro-Doppler signature is of particular importance. We have carried out numerical and experimental studies of the RCS and the micro-Doppler of an example commercial drone in order to study its detectability with radar systems.

Shape optimization for aerodynamic efficiency and low observability

NASA Technical Reports Server (NTRS)

Vinh, Hoang; Van Dam, C. P.; Dwyer, Harry A.

1993-01-01

Field methods based on the finite-difference approximations of the time-domain Maxwell's equations and the potential-flow equation have been developed to solve the multidisciplinary problem of airfoil shaping for aerodynamic efficiency and low radar cross section (RCS). A parametric study and an optimization study employing the two analysis methods are presented to illustrate their combined capabilities. The parametric study shows that for frontal radar illumination, the RCS of an airfoil is independent of the chordwise location of maximum thickness but depends strongly on the maximum thickness, leading-edge radius, and leadingedge shape. In addition, this study shows that the RCS of an airfoil can be reduced without significant effects on its transonic aerodynamic efficiency by reducing the leading-edge radius and/or modifying the shape of the leading edge. The optimization study involves the minimization of wave drag for a non-lifting, symmetrical airfoil with constraints on the airfoil maximum thickness and monostatic RCS. This optimization study shows that the two analysis methods can be used effectively to design aerodynamically efficient airfoils with certain desired RCS characteristics.

Functional incapacity related to rotator cuff syndrome in workers. Is it influenced by social characteristics and medical management?

PubMed

Champagne, Romain; Bodin, Julie; Fouquet, Natacha; Roquelaure, Yves; Petit, Audrey

2017-12-04

Survey. Rotator cuff syndrome (RCS) is one of the most common musculoskeletal disorders reported in workers. The functional incapacity related to RCS may vary according to the sociodemographic context and to the medical management. The purpose of this is to analyze the RCS-related functional incapacity assessed by the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaires in workers according to their sociodemographic characteristics and the use of care. A cross-sectional study was carried out on a French sample of workers diagnosed with RCS. The DASH and DASH-work scores were studied according to the sociodemographic factors, musculoskeletal symptoms, and RCS medical management during the preceding 12 months. Two hundred seven workers who suffered from RCS filled out the questionnaire of which 80% were still working. The DASH score was significantly higher in women (24.0 vs 17.4; P < .01; effect size (d) = 0.39), in patients over the age of 50 years (23.6 vs 11.3; P < .005) and in case of another upper limb musculoskeletal disorder (P < .0001; d ≥ 0.4). The DASH and DASH-work scores were significantly higher in case of use of care for RCS (P < .005; d > 0.6). The demographic factors and the RCS medical management influenced the overall incapacity assessed by the DASH questionnaire. Work incapacity was more especially related to the use of care for RCS. The sociodemographic and medical parameters added to other established predictors could help guide clinicians in managing their patients. Copyright © 2017 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

First upper limits on the radar cross section of cosmic-ray induced extensive air showers

NASA Astrophysics Data System (ADS)

Abbasi, R. U.; Abe, M.; Abou Bakr Othman, M.; Abu-Zayyad, T.; Allen, M.; Anderson, R.; Azuma, R.; Barcikowski, E.; Belz, J. W.; Bergman, D. R.; Besson, D.; Blake, S. A.; Byrne, M.; Cady, R.; Chae, M. J.; Cheon, B. G.; Chiba, J.; Chikawa, M.; Cho, W. R.; Farhang-Boroujeny, B.; Fujii, T.; Fukushima, M.; Gillman, W. H.; Goto, T.; Hanlon, W.; Hanson, J. C.; Hayashi, Y.; Hayashida, N.; Hibino, K.; Honda, K.; Ikeda, D.; Inoue, N.; Ishii, T.; Ishimori, R.; Ito, H.; Ivanov, D.; Jayanthmurthy, C.; Jui, C. C. H.; Kadota, K.; Kakimoto, F.; Kalashev, O.; Kasahara, K.; Kawai, H.; Kawakami, S.; Kawana, S.; Kawata, K.; Kido, E.; Kim, H. B.; Kim, J. H.; Kim, J. H.; Kitamura, S.; Kitamura, Y.; Kunwar, S.; Kuzmin, V.; Kwon, Y. J.; Lan, J.; Lim, S. I.; Lundquist, J. P.; Machida, K.; Martens, K.; Matsuda, T.; Matsuyama, T.; Matthews, J. N.; Minamino, M.; Mukai, K.; Myers, I.; Nagasawa, K.; Nagataki, S.; Nakamura, T.; Nonaka, T.; Nozato, A.; Ogio, S.; Ogura, J.; Ohnishi, M.; Ohoka, H.; Oki, K.; Okuda, T.; Ono, M.; Oshima, A.; Ozawa, S.; Park, I. H.; Prohira, S.; Pshirkov, M. S.; Rezazadeh-Reyhani, A.; Rodriguez, D. C.; Rubtsov, G.; Ryu, D.; Sagawa, H.; Sakurai, N.; Sampson, A. L.; Scott, L. M.; Schurig, D.; Shah, P. D.; Shibata, F.; Shibata, T.; Shimodaira, H.; Shin, B. K.; Smith, J. D.; Sokolsky, P.; Springer, R. W.; Stokes, B. T.; Stratton, S. R.; Stroman, T. A.; Suzawa, T.; Takai, H.; Takamura, M.; Takeda, M.; Takeishi, R.; Taketa, A.; Takita, M.; Tameda, Y.; Tanaka, H.; Tanaka, K.; Tanaka, M.; Thomas, S. B.; Thomson, G. B.; Tinyakov, P.; Tkachev, I.; Tokuno, H.; Tomida, T.; Troitsky, S.; Tsunesada, Y.; Tsutsumi, K.; Uchihori, Y.; Udo, S.; Urban, F.; Vasiloff, G.; Venkatesh, S.; Wong, T.; Yamane, R.; Yamaoka, H.; Yamazaki, K.; Yang, J.; Yashiro, K.; Yoneda, Y.; Yoshida, S.; Yoshii, H.; Zollinger, R.; Zundel, Z.

2017-01-01

TARA (Telescope Array Radar) is a cosmic ray radar detection experiment colocated with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. The TARA detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting antenna which broadcasts the radar carrier over the SD array and within the FD field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data since 2013 with the primary goal of observing the radar signatures of extensive air showers (EAS). Simulations indicate that echoes are expected to be short in duration (∼ 10 μs) and exhibit rapidly changing frequency, with rates on the order 1 MHz/μs. The EAS radar cross-section (RCS) is currently unknown although it is the subject of over 70 years of speculation. A novel signal search technique is described in which the expected radar echo of a particular air shower is used as a matched filter template and compared to waveforms obtained by triggering the radar DAQ using the Telescope Array fluorescence detector. No evidence for the scattering of radio frequency radiation by EAS is obtained to date. We report the first quantitative RCS upper limits using EAS that triggered the Telescope Array Fluorescence Detector. The transmitter is under the direct control of experimenters, and in a radio-quiet area isolated from other radio frequency (RF) sources. The power and radiation pattern are known at all times. Forward power up to 40 kW and gain exceeding 20 dB maximize energy density in the radar field. Continuous wave (CW) transmission gives 100% duty cycle, as opposed to pulsed radar. TARA utilizes a high sample rate DAQ (250 MS/s). TARA is colocated with a large state-of-the-art conventional CR observatory, allowing the radar data stream to be sampled at the arrival times of known cosmic ray events. Each of these attributes of the TARA detector has been discussed in detail in the literature [8]. A map showing the TA SD array and the location of the TARA transmitter and receiver is shown in Fig. 1.Section 2 of this paper includes a description of air shower plasmas and possible radio scattering mechanisms. Theoretical and experimental parameters that influence radio scattering are presented and discussed. We justify use of the thin wire model in a radar echo simulation that predicts echo waveforms, which we will subsequently (Section 6) use in placing limits on the air shower radar cross section (RCS). Sections 3 and 4 describe TARA data and offline processing techniques. In Section 5, we describe the signal search using simulated waveforms as matched filter (MF) templates in order to maximize sensitivity. Section 6 describes the procedure for calculating a scale factor to the RCS model described in Section 2, the results of which are used in placing the first quantitative upper limit on the EAS radar cross-section (RCS). In Section 7 we summarize these results and discuss the viability of radar detection of cosmic rays in light of the TARA findings.

Effect of root canal sealer and artificial accelerated aging on fibreglass post bond strength to intraradicular dentin.

PubMed

Santana, Fernanda-Ribeiro; Soares, Carlos-José; Ferreira, Josemar-Martins; Valdivi, Andréa-Dolores-Correia-Miranda; Souza, João-Batista-de; Estrela, Carlos

2014-10-01

To evaluate the effect of root canal sealers (RCS) and specimen aging on the bond strength of fibre posts to bovine intraradicular dentin. 80 teeth were used according the groups - Sealapextm, Sealer 26®, AH Plus® and specimens aging - test with no aging and with aging. The canals prepared were filled using one of each RCS. The posts were cemented. Roots were cross-sectioned to obtain two slices of each third. Samples were submitted to push-out test. Failure mode was evaluated under a confocal microscope. The data were analysed by ANOVA, Tukey's, and Dunnet tests (α = 0.05). No significant difference was detected among RCS. Aged control presented higher bond strength than immediate control. The aging did not result significant difference. Adhesive cement-dentin failure was prevalent in all groups. RCS interfered negatively with bonding of fibreglass posts cemented with self-adhesive resin cement to intraradicular dentin. Key words:Fibreglass post, bond strength, root dentin, endodontic sealer, aging.

Pixelated Checkerboard Metasurface for Ultra-Wideband Radar Cross Section Reduction.

PubMed

Haji-Ahmadi, Mohammad-Javad; Nayyeri, Vahid; Soleimani, Mohammad; Ramahi, Omar M

2017-09-12

In this paper we designed and fabricated a metasurface working as a radar cross section (RCS) reducer over an ultra wide band of frequency from 3.8 to 10.7 GHz. The designed metasurface is a chessboard-like surface made of alternating tiles, with each tile composed of identical unit cells. We develop a novel, simple, highly robust and fully automated approach for designing the unit cells. First, a topology optimization algorithm is used to engineer the shape of the two unit cells. The area of each unit cell is pixelated. A particle swarm optimization algorithm is applied wherein each pixel corresponds to a bit having a binary value of 1 or 0 indicating metallization or no metallization. With the objective of reducing the RCS over a specified frequency range, the optimization algorithm is then linked to a full wave three-dimensional electromagnetic simulator. To validate the design procedure, a surface was designed, fabricated and experimentally tested showing significantly enhanced performance than previous works. Additionally, angular analysis is also presented showing good stability and wide-angle behavior of the designed RCS reducer. The automated design procedure has a wide range of applications and can be easily extended to design surfaces for antennas, energy harvesters, noise mitigation in electronic circuit boards amongst others.

Metamaterial for Radar Frequencies

DTIC Science & Technology

2012-09-01

Circuit Board RAM Radar Absorbing Material RCS Radar Cross Section SNR Signal-to-Noise Ratio SNG Single-Negative SRR Split Ring Resonator...although some can be single-negative ( SNG ). DNG refers to material with simultaneous negative real parts of the permittivity r  and permeability

Special Course on Fundamentals of Fighter Aircraft Design

DTIC Science & Technology

1987-10-01

mounted centrally on a cylindrical fuselage of circular cross-section. Here the fuselage interference is shown by a calculation with an exact...M. and Schiff, L.B., "Aerodynamic Mathematical Modeling - Basic Concepts", AGARD-LS-114, 1981, Lecture 1. 30. Malcolm, G.N., "Rotary and Magnus ...thin cylindrical Intake 1.5.3. Real Intake equivalence 1.5.4. Lip thickness and auxiliary intake design 1.6. AIR INTAKE RADAR CROSS SECTION (R.C.S

Automation of an RCS (Radar Cross Section) Measurement System and Its Application to Investigate the Electromagnetic Scattering from Scale Model Aircraft Canopies

DTIC Science & Technology

1989-12-01

8217 -E ep IP 760 7v rag-2-t 7 -vet ca vo - a~ .:cz : 112 !] 10 Star-, requency i- -in.- -,,z. 200 :1h too t rouencv, i ax. 210 N T iarizat~on i2:)15. 220... 10 2-3 Pyramidal Radar Absorbing Material (RAM) ... . 11 2-4 Hardware configuration .... ............. 13 2-5 Point source model for phase variation...two plates ....... 51 4- 10 Gated RCS of 4 inch circular flat plate a) time doi. ain and b) frequency response . . . . 52 5-1 Measurement test matrix

Metal radomes for reduced RCS performance

NASA Astrophysics Data System (ADS)

Wahid, M.; Morris, S. B.

A frequency selective surface (FSS) comprising a square grid and a hexagonal array of disks is proposed as a means of reducing the Radar Cross Section (RCS) of a radar bay over a wide (2 GHz to 14.6 GHz) frequency bandwidth. Results are presented in terms of transmission loss for an 'A'-type sandwich radome consisting of two FSS layers for normal and non-normal incidence. A single FSS layer on a GRP flat panel is also considered. Good agreement is found between the predicted and measured results. The proposed FSS shows good performance and is relatively insensitive to angle of incidence between 3.8 GHz and 10.1 GHz. Predicted Insertion Phase Delay (IPD) and cross-polar performances are also given. Parametric studies have indicated the versatility of the proposed structure.

Target scattering characteristics for OAM-based radar

NASA Astrophysics Data System (ADS)

Liu, Kang; Gao, Yue; Li, Xiang; Cheng, Yongqiang

2018-02-01

The target scattering characteristics are crucial for radar systems. However, there is very little study conducted for the recently developed orbital angular momentum (OAM) based radar system. To illustrate the role of OAM-based radar cross section (ORCS), conventional radar equation is modified by taking characteristics of the OAM waves into account. Subsequently, the ORCS is defined in analogy to classical radar cross section (RCS). The unique features of the incident OAM-carrying field are analyzed. The scattered field is derived, and the analytical expressions of ORCSs for metal plate and cylinder targets are obtained. Furthermore, the ORCS and RCS are compared to illustrate the influences of OAM mode number, target size and signal frequency on the ORCS. Analytical studies demonstrate that the mirror-reflection phenomenon disappears and peak values of ORCS are in the non-specular direction. Finally, the ORCS features are summarized to show its advantages in radar target detection. This work can provide theoretical guidance to the design of OAM-based radar as well as the target detection and identification applications.

Design and fabrication of a microstrip patch antenna with a low radar cross section in the X-band

NASA Astrophysics Data System (ADS)

Jang, Hong-Kyu; Lee, Won-Jun; Kim, Chun-Gon

2011-01-01

In this study, the authors developed a radar absorbing method to reduce the antenna radar cross section (RCS) without any loss of antenna performance. The new method was based upon an electromagnetic bandgap (EBG) absorber using conducting polymer (CP). First, a microstrip patch antenna was made by using a copper film and glass/epoxy composite materials, which are typically used for load-bearing structures, such as aircraft and other vehicles. Then, CP EBG patterns were also designed that had a 90% electromagnetic (EM) wave absorbing performance within the X-band (8.2-12.4 GHz). Finally, the CP EBG patterns were printed on the top surface of the microstrip patch antenna. The measured radar absorbing performance of the fabricated patch antenna showed that the frontal RCS of the antenna declined by nearly 95% at 10 GHz frequency while the CP EBG patterns had almost no effect on the antenna's performance.

Simulations and measurements of a radar cross section of a Boeing 747-200 in the 20-60 MHz frequency band

NASA Astrophysics Data System (ADS)

David, A.; Brousseau, C.; Bourdillon, A.

2003-08-01

HF and VHF low frequency bands provide a promising way to perform radar target recognition. At these frequencies, Radar Cross Section (RCS) behavior is not well known because the scattered field is due to a complex phenomenon where the interactions between the different parts of the structure have a significant contribution, which makes the prediction difficult. A wire model of a commercial Boeing 747-200 aircraft, developed to be used with the Numerical Electromagnetic Code (NEC), is presented. The reliability of this model has been assessed by comparing the results given by NEC with the measurements made in an anechoïc chamber with a scaled aircraft, and a relatively good agreement was observed between simulations and measurements. The RCS variations of an aircraft along different flight routes have been investigated, and it is shown that it is necessary to know the flight route of the airplane to envisage target identification in spite of the use of the low frequency band.

Automated target recognition using passive radar and coordinated flight models

NASA Astrophysics Data System (ADS)

Ehrman, Lisa M.; Lanterman, Aaron D.

2003-09-01

Rather than emitting pulses, passive radar systems rely on illuminators of opportunity, such as TV and FM radio, to illuminate potential targets. These systems are particularly attractive since they allow receivers to operate without emitting energy, rendering them covert. Many existing passive radar systems estimate the locations and velocities of targets. This paper focuses on adding an automatic target recognition (ATR) component to such systems. Our approach to ATR compares the Radar Cross Section (RCS) of targets detected by a passive radar system to the simulated RCS of known targets. To make the comparison as accurate as possible, the received signal model accounts for aircraft position and orientation, propagation losses, and antenna gain patterns. The estimated positions become inputs for an algorithm that uses a coordinated flight model to compute probable aircraft orientation angles. The Fast Illinois Solver Code (FISC) simulates the RCS of several potential target classes as they execute the estimated maneuvers. The RCS is then scaled by the Advanced Refractive Effects Prediction System (AREPS) code to account for propagation losses that occur as functions of altitude and range. The Numerical Electromagnetic Code (NEC2) computes the antenna gain pattern, so that the RCS can be further scaled. The Rician model compares the RCS of the illuminated aircraft with those of the potential targets. This comparison results in target identification.

The Effects of Plasma Shield on the Radar Cross Section of a Generic Missile in UHF Band

NASA Astrophysics Data System (ADS)

Chung, Shen

2011-10-01

RF Stealth is the dominant technology in today's military aircraft, and most is achieved by shape design with a few reductions achieved by RAM, but most of these effects are only valid in X band. With the popularity of UHF radar again rising, the possibility of detecting a stealth object has increased due to resonance effect, and this is difficult to decrease with previous means due to the long wavelength. A plasma shield generated in front of an object may be suitable to alter the RCS in specific band without physically changing its shape. We examine the RCS of a generic missile in UHF band, and compared it with one with a cone-shape plasma generated in front of the missile. We find the plasma effectively changes the RCS of the missile, though not necessarily smaller. The RCS of the missile with the plasma shield is now dominated by the plasma instead of the missile. The RCS is a function of the size, shape, and density of the plasma shield. For higher frequency signals like the X band radar, it can still penetrate the plasma, and sees the original RCS of the missile. Due to the relatively lower UHF frequency, the plasma density needed is lower than one in X band and thus more practical to achieve.

A robust algorithm for automated target recognition using precomputed radar cross sections

NASA Astrophysics Data System (ADS)

Ehrman, Lisa M.; Lanterman, Aaron D.

2004-09-01

Passive radar is an emerging technology that offers a number of unique benefits, including covert operation. Many such systems are already capable of detecting and tracking aircraft. The goal of this work is to develop a robust algorithm for adding automated target recognition (ATR) capabilities to existing passive radar systems. In previous papers, we proposed conducting ATR by comparing the precomputed RCS of known targets to that of detected targets. To make the precomputed RCS as accurate as possible, a coordinated flight model is used to estimate aircraft orientation. Once the aircraft's position and orientation are known, it is possible to determine the incident and observed angles on the aircraft, relative to the transmitter and receiver. This makes it possible to extract the appropriate radar cross section (RCS) from our simulated database. This RCS is then scaled to account for propagation losses and the receiver's antenna gain. A Rician likelihood model compares these expected signals from different targets to the received target profile. We have previously employed Monte Carlo runs to gauge the probability of error in the ATR algorithm; however, generation of a statistically significant set of Monte Carlo runs is computationally intensive. As an alternative to Monte Carlo runs, we derive the relative entropy (also known as Kullback-Liebler distance) between two Rician distributions. Since the probability of Type II error in our hypothesis testing problem can be expressed as a function of the relative entropy via Stein's Lemma, this provides us with a computationally efficient method for determining an upper bound on our algorithm's performance. It also provides great insight into the types of classification errors we can expect from our algorithm. This paper compares the numerically approximated probability of Type II error with the results obtained from a set of Monte Carlo runs.

Numerical methods for analyzing electromagnetic scattering

NASA Technical Reports Server (NTRS)

Lee, S. W.; Lo, Y. T.; Chuang, S. L.; Lee, C. S.

1985-01-01

Numerical methods to analyze electromagnetic scattering are presented. The dispersions and attenuations of the normal modes in a circular waveguide coated with lossy material were completely analyzed. The radar cross section (RCS) from a circular waveguide coated with lossy material was calculated. The following is observed: (1) the interior irradiation contributes to the RCS much more than does the rim diffraction; (2) at low frequency, the RCS from the circular waveguide terminated by a perfect electric conductor (PEC) can be reduced more than 13 dB down with a coating thickness less than 1% of the radius using the best lossy material available in a 6 radius-long cylinder; (3) at high frequency, a modal separation between the highly attenuated and the lowly attenuated modes is evident if the coating material is too lossy, however, a large RCS reduction can be achieved for a small incident angle with a thin layer of coating. It is found that the waveguide coated with a lossy magnetic material can be used as a substitute for a corrugated waveguide to produce a circularly polarized radiation yield.

Millimeter wave backscatter measurements in support of collision avoidance applications

NASA Astrophysics Data System (ADS)

Narayanan, Ram M.; Snuttjer, Brett R. J.

1997-11-01

Millimeter-wave short range radar systems have unique advantages in surface navigation applications, such as military vehicle mobility, aircraft landing assistance, and automotive collision avoidance. In collision avoidance applications, characterization of clutter due to terrain and roadside objects is necessary in order to maximize the signal-to-clutter ratio (SCR) and to minimize false alarms. The results of two types of radar cross section (RCS) measurements at 95 GHz are reported in this paper. The first set of measurements presents data on the normalized RCS (NRCS) as well as clutter distributions of various terrain types at low grazing angles of 5° and 7.5°. The second set of measurements presents RCS data and statistics on various types of roadside objects, such as metallic and wooden sign posts. These results are expected to be useful for designers of short-range millimeter-wave collision avoidance radar systems.

Finite difference time domain electromagnetic scattering from frequency-dependent lossy materials

NASA Technical Reports Server (NTRS)

Luebbers, Raymond J.; Beggs, John H.

1991-01-01

Four different FDTD computer codes and companion Radar Cross Section (RCS) conversion codes on magnetic media are submitted. A single three dimensional dispersive FDTD code for both dispersive dielectric and magnetic materials was developed, along with a user's manual. The extension of FDTD to more complicated materials was made. The code is efficient and is capable of modeling interesting radar targets using a modest computer workstation platform. RCS results for two different plate geometries are reported. The FDTD method was also extended to computing far zone time domain results in two dimensions. Also the capability to model nonlinear materials was incorporated into FDTD and validated.

Research on the FDTD method of scattering effects of obliquely incident electromagnetic waves in time-varying plasma sheath on collision and plasma frequencies

NASA Astrophysics Data System (ADS)

Chen, Wei; Guo, Li-xin; Li, Jiang-ting

2017-04-01

This study analyzes the scattering characteristics of obliquely incident electromagnetic (EM) waves in a time-varying plasma sheath. The finite-difference time-domain algorithm is applied. According to the empirical formula of the collision frequency in a plasma sheath, the plasma frequency, temperature, and pressure are assumed to vary with time in the form of exponential rise. Some scattering problems of EM waves are discussed by calculating the radar cross section (RCS) of the time-varying plasma. The laws of the RCS varying with time are summarized at the L and S wave bands.

Optimization of Passive Coherent Receiver System Placement

DTIC Science & Technology

2013-09-01

spheroid object with a constant radar cross section (RCS). Additionally, the receiver and transmitters are assumed to be notional isotropic antennae...software- defined radio for equatorial plasma instability studies,” Radio Science, vol. 48, pp. 1–11. Aug. 2013. [2] P. C. Zhang and B. Y. Li, “Passive

Broadband and Broad-angle Polarization-independent Metasurface for Radar Cross Section Reduction

PubMed Central

Sun, Hengyi; Gu, Changqing; Chen, Xinlei; Li, Zhuo; Liu, Liangliang; Xu, Bingzheng; Zhou, Zicheng

2017-01-01

In this work, a broadband and broad-angle polarization-independent random coding metasurface structure is proposed for radar cross section (RCS) reduction. An efficient genetic algorithm is utilized to obtain the optimal layout of the unit cells of the metasurface to get a uniform backscattering under normal incidence. Excellent agreement between the simulation and experimental results show that the proposed metasurface structure can significantly reduce the radar cross section more than 10 dB from 17 GHz to 42 GHz when the angle of incident waves varies from 10° to 50°. The proposed coding metasurface provides an efficient scheme to reduce the scattering of the electromagnetic waves. PMID:28106090

Broadband and Broad-angle Polarization-independent Metasurface for Radar Cross Section Reduction.

PubMed

Sun, Hengyi; Gu, Changqing; Chen, Xinlei; Li, Zhuo; Liu, Liangliang; Xu, Bingzheng; Zhou, Zicheng

2017-01-20

In this work, a broadband and broad-angle polarization-independent random coding metasurface structure is proposed for radar cross section (RCS) reduction. An efficient genetic algorithm is utilized to obtain the optimal layout of the unit cells of the metasurface to get a uniform backscattering under normal incidence. Excellent agreement between the simulation and experimental results show that the proposed metasurface structure can significantly reduce the radar cross section more than 10 dB from 17 GHz to 42 GHz when the angle of incident waves varies from 10° to 50°. The proposed coding metasurface provides an efficient scheme to reduce the scattering of the electromagnetic waves.

Inband radar cross section of phased arrays with parallel feeds

NASA Astrophysics Data System (ADS)

Flokas, Vassilios

1994-06-01

Approximate formulas for the inband radar cross section of arrays with parallel feeds are presented. To obtain the formulas, multiple reflections are neglected, and devices of the same type are assumed to have identical electrical performance. The approximate results were compared to the results obtained using a scattering matrix formulation. Both methods were in agreement in predicting RCS lobe positions, levels, and behavior with scanning. The advantages of the approximate method are its computational efficiency and its flexibility in handling an arbitrary number of coupler levels.

Translational evidence of prothrombotic and inflammatory endothelial damage in Cushing syndrome after remission.

PubMed

Aranda, Gloria; Fernandez-Ruiz, Rebeca; Palomo, Marta; Romo, Mónica; Mora, Mireia; Halperin, Irene; Casals, Gregori; Enseñat, Joaquim; Vidal, Oscar; Diaz-Ricart, Maribel; Hanzu, Felicia A

2018-03-01

Sustained evidence from observational studies indicates that after remission of Cushing syndrome (CS) a cardiovascular risk phenotype persists. Here, we performed a translational study in active CS and CS in remission (RCS) to evaluate the subclinical cardiometabolic burden and to explore the direct pro-inflammatory and prothrombotic potential of their sera on the endothelium in an in vitro translational atherothrombotic cell model. Cross sectional study. The groups were (n = 9/group): I. RCS; II. Active CS (ACS) and III. Controls (CTR), all matched for age, body mass index, sex, without other hormonal deficits. We evaluated in vivo: cardiometabolic profile; endothelial markers (sVCAM-1, NO); endothelial dysfunction (FMD); intima-media thickness and body composition (DEXA). In vitro endothelial cells (EC) were exposed to sera taken from the different subjects to evaluate inflammatory EC response (tisVCAM) and thrombogenicity of the generated extracellular matrix (ECM): von Willebrand factor (VWF) and platelet reactivity. Three of the 9 RCS subjects were on glucocorticoid replacement therapy (GC-RT). Patients on GC-RT had a shorter period of time in stable remission. In vivo analysis ACS showed typically metabolic features, while cardiometabolic markers reached statistical significance for RCS only for Hs-CRP (P < .01). In vitro:EC exposed to ACS and RCS sera displayed increased tisVCAM-1 (P < .01 for ACS and P < .05 for RCS vs CTR), VWF (P < .01 for ACS and P < .05 for RCS vs CTR) and platelet adhesion on ECM (P < .01 for ACC and P < .05 for RCS vs CTR). No statistically significant differences were observed between GC-RT RSC and RCS without GC-RT. The sera of premenopausal women with CS in remission, without atherothrombotic disease, contain circulatory endothelial deleterious factors with a direct thrombogenic and pro-inflammatory endothelial effect that could increase cardiovascular risk. © 2017 John Wiley & Sons Ltd.

Scattering Cross Section of Sound Waves by the Modal Element Method

NASA Technical Reports Server (NTRS)

Baumeister, Kenneth J.; Kreider, Kevin L.

1994-01-01

#he modal element method has been employed to determine the scattered field from a plane acoustic wave impinging on a two dimensional body. In the modal element method, the scattering body is represented by finite elements, which are coupled to an eigenfunction expansion representing the acoustic pressure in the infinite computational domain surrounding the body. The present paper extends the previous work by developing the algorithm necessary to calculate the acoustics scattering cross section by the modal element method. The scattering cross section is the acoustical equivalent to the Radar Cross Section (RCS) in electromagnetic theory. Since the scattering cross section is evaluated at infinite distance from the body, an asymptotic approximation is used in conjunction with the standard modal element method. For validation, the scattering cross section of the rigid circular cylinder is computed for the frequency range 0.1 is less than or equal to ka is less than or equal to 100. Results show excellent agreement with the analytic solution.

From the smallest to the largest - The measurement of radar cross sections at CELAR

NASA Astrophysics Data System (ADS)

Gadenne, Philippe; Gaudon, Pierre; Motet, Jean-Claude; Puech, Olivier

Recent improvements implemented at CELAR RCS-measuring facilities are described, and some typical results are presented. Particular attention is given to: (1) improvement of anechoic-chamber measurement methods; (2) data processing with LEADER software for the STRADI facility; and (3) operation of a full-scale military aircraft measurement facility.

Signal analysis by means of time-frequency (Wigner-type) distributions -- Applications to sonar and radar echoes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaunaurd, G.; Strifors, H.C.

1996-09-01

Time series data have been traditionally analyzed in either the time or the frequency domains. For signals with a time-varying frequency content, the combined time-frequency (TF) representations, based on the Cohen class of (generalized) Wigner distributions (WD`s) offer a powerful analysis tool. Using them, it is possible to: (1) trace the time-evolution of the resonance features usually present in a standard sonar cross section (SCS), or in a radar cross section (RCS) and (2) extract target information that may be difficult to even notice in an ordinary SCS or RCS. After a brief review of the fundamental properties of themore » WD, the authors discuss ways to reduce or suppress the cross term interference that appears in the WD of multicomponent systems. These points are illustrated with a variety of three-dimensional (3-D) plots of Wigner and pseudo-Wigner distributions (PWD), in which the strength of the distribution is depicted as the height of a Wigner surface with height scales measured by various color shades or pseudocolors. The authors also review studies they have made of the echoes returned by conducting or dielectric targets in the atmosphere, when they are illuminated by broadband radar pings. A TF domain analysis of these impulse radar returns demonstrates their superior informative content. These plots allow the identification of targets in an easier and clearer fashion than by the conventional RCS of narrowband systems. The authors show computed and measured plots of WD and PWD of various types of aircraft to illustrate the classification advantages of the approach at any aspect angle. They also show analogous results for metallic objects buried underground, in dielectric media, at various depths.« less

Improvement on RCS reduction using flat lossy focusing reflectors.

PubMed

Chin, Cheng-Yuan; Jou, Christina F

2013-12-30

In this paper, we propose a planar non-periodic subwavelength resistive grating (SWRG). The phase front of the scattered fields can be completely manipulated through non-periodic design of the grating while high absorptivity is preserved. The SWRG has an interesting property similar to a resistive concave reflecting lens. Scattered wave is focused in the near-field region, and spread out in the far-field. This feature of non-periodic resistive grating can improve the original radar cross section (RCS) reduction up to 22.86 dB in the boresight direction comparing to the periodic counterpart. Non-periodic design of SWRG could have a substantial impact on stealth technology, aerospace engineering, and microwave anechoic chamber.

Shooting and bouncing rays - Calculating the RCS of an arbitrarily shaped cavity

NASA Technical Reports Server (NTRS)

Ling, Hao; Chou, Ri-Chee; Lee, Shung-Wu

1989-01-01

A ray-shooting approach is presented for calculating the interior radar cross section (RCS) from a partially open cavity. In the problem considered, a dense grid of rays is launched into the cavity through the opening. The rays bounce from the cavity walls based on the laws of geometrical optics and eventually exit the cavity via the aperture. The ray-bouncing method is based on tracking a large number of rays launched into the cavity through the opening and determining the geometrical optics field associated with each ray by taking into consideration (1) the geometrical divergence factor, (2) polarization, and (3) material loading of the cavity walls. A physical optics scheme is then applied to compute the backscattered field from the exit rays. This method is so simple in concept that there is virtually no restriction on the shape or material loading of the cavity. Numerical results obtained by this method are compared with those for the modal analysis for a circular cylinder terminated by a PEC plate. RCS results for an S-bend circular cylinder generated on the Cray X-MP supercomputer show significant RCS reduction. Some of the limitations and possible extensions of this technique are discussed.

Backscattered EM-wave manipulation using low cost 1-bit reflective surface at W-band

NASA Astrophysics Data System (ADS)

Taher Al-Nuaimi, Mustafa K.; Hong, Wei; He, Yejun

2018-04-01

The design of low cost 1-bit reflective (non-absorptive) surfaces for manipulation of backscattered EM-waves and radar cross section (RCS) reduction at W-band is presented in this article. The presented surface is designed based on the reflection phase cancellation principle. The unit cell used to compose the proposed surface has an obelus (division symbol of short wire and two disks above and below) like shape printed on a grounded dielectric material. Using this unit cell, surfaces that can efficiently manipulate the backscattered RCS pattern by using the proposed obelus-shaped unit cell (as ‘0’ element) and its mirrored unit cell (as ‘1’ element) in one surface with a 180°  ±  35° reflection phase difference between their reflection phases are designed. The proposed surfaces can generate various kinds of backscattered RCS patterns, such as single, three, or four lobes or even a low-level (reduced RCS) diffused reflection pattern when those two unit cells are distributed randomly across the surface aperture. For experimental characterization purposes, a 50  ×  50 mm2 surface is fabricated and measured.

An investigation of the RCS (radar cross section) computation of grid cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sabihi, Ahmad

2014-12-10

In this paper, the aperture of a cavity is covered by a metallic grid net. This metallic grid is to reduce RCS deduced by impinging radar ray on the aperture. A radar ray incident on a grid net installed on a cavity may create six types of propagation. 1-Incident rays entering inside the cavity and backscattered from it.2-Incidebnt rays on the grid net and created reection rays as an array of scatterers. These rays may create a wave with phase difference of 180 degree with respect to the exiting rays from the cavity.3-Incident rays on the grid net create surfacemore » currents owing on the net and make travelling waves, which regenerate the magnetic and electric fields. These fields make again propagated waves against incident ones.4-Creeping waves.5-Diffracted rays due to leading edges of net’s elements.6-Mutual impedance among elements of the net could be effective on the resultant RCS. Therefore, the author compares the effects of three out of six properties to a cavity without grid net. This comparison shows that RCS prediction of cavity having a grid net is much more reduced than that of without one.« less

Uneven-Layered Coding Metamaterial Tile for Ultra-wideband RCS Reduction and Diffuse Scattering.

PubMed

Su, Jianxun; He, Huan; Li, Zengrui; Yang, Yaoqing Lamar; Yin, Hongcheng; Wang, Junhong

2018-05-25

In this paper, a novel uneven-layered coding metamaterial tile is proposed for ultra-wideband radar cross section (RCS) reduction and diffuse scattering. The metamaterial tile is composed of two kinds of square ring unit cells with different layer thickness. The reflection phase difference of 180° (±37°) between two unit cells covers an ultra-wide frequency range. Due to the phase cancellation between two unit cells, the metamaterial tile has the scattering pattern of four strong lobes deviating from normal direction. The metamaterial tile and its 90-degree rotation can be encoded as the '0' and '1' elements to cover an object, and diffuse scattering pattern can be realized by optimizing phase distribution, leading to reductions of the monostatic and bi-static RCSs simultaneously. The metamaterial tile can achieve -10 dB RCS reduction from 6.2 GHz to 25.7 GHz with the ratio bandwidth of 4.15:1 at normal incidence. The measured and simulated results are in good agreement and validate the proposed uneven-layered coding metamaterial tile can greatly expanding the bandwidth for RCS reduction and diffuse scattering.

Electromagnetic-wave propagation in unmagnetized plasmas

NASA Astrophysics Data System (ADS)

Gregoire, D. J.; Santoru, J.; Schumacher, R. W.

1992-03-01

This final report describes an investigation of electromagnetic-wave propagation in unmagnetized plasmas and its application to the reduction of the radar cross section (RCS) of a plasma-filled enclosure. We have demonstrated RCS reduction of 20 to 25 dB with a prototype system at the radar range at Hughes Aircraft's Microwave Products Division in Torrance. The prototype consists of a sealed ceramic enclosure with a microwave reflector and a plasma generator inside it. When the plasma is present, the RCS is significantly reduced over a frequency range of 4 to 14 GHz. As part of the program, we also investigated the basic-plasma-physics issues relating to the absorption and refraction of electromagnetic (EM) waves in collisional plasmas. We demonstrated absorption as high as 63 dB in a section of plasma-loaded C-band rectangular waveguide. We also developed a theoretical model for the plasma cloaking process that includes scattering contributions from the plasma-vacuum interface, partial reflections from the plasma, and collisional absorption in the plasma. The theoretical model is found to be in reasonable agreement with the experimental results and can be used to confidently design future plasma cloaking systems.

Numerical methods for analyzing electromagnetic scattering

NASA Technical Reports Server (NTRS)

Lee, S. W.; Lo, Y. T.; Chuang, S. L.; Lee, C. S.

1985-01-01

Attenuation properties of the normal modes in an overmoded waveguide coated with a lossy material were analyzed. It is found that the low-order modes, can be significantly attenuated even with a thin layer of coating if the coating material is not too lossy. A thinner layer of coating is required for large attenuation of the low-order modes if the coating material is magnetic rather than dielectric. The Radar Cross Section (RCS) from an uncoated circular guide terminated by a perfect electric conductor was calculated and compared with available experimental data. It is confirmed that the interior irradiation contributes to the RCS. The equivalent-current method based on the geometrical theory of diffraction (GTD) was chosen for the calculation of the contribution from the rim diffraction. The RCS reduction from a coated circular guide terminated by a PEC are planned schemes for the experiments are included. The waveguide coated with a lossy magnetic material is suggested as a substitute for the corrugated waveguide.

SAR image filtering based on the heavy-tailed Rayleigh model.

PubMed

Achim, Alin; Kuruoğlu, Ercan E; Zerubia, Josiane

2006-09-01

Synthetic aperture radar (SAR) images are inherently affected by a signal dependent noise known as speckle, which is due to the radar wave coherence. In this paper, we propose a novel adaptive despeckling filter and derive a maximum a posteriori (MAP) estimator for the radar cross section (RCS). We first employ a logarithmic transformation to change the multiplicative speckle into additive noise. We model the RCS using the recently introduced heavy-tailed Rayleigh density function, which was derived based on the assumption that the real and imaginary parts of the received complex signal are best described using the alpha-stable family of distribution. We estimate model parameters from noisy observations by means of second-kind statistics theory, which relies on the Mellin transform. Finally, we compare the proposed algorithm with several classical speckle filters applied on actual SAR images. Experimental results show that the homomorphic MAP filter based on the heavy-tailed Rayleigh prior for the RCS is among the best for speckle removal.

Accurate Analysis of Target Characteristic in Bistatic SAR Images: A Dihedral Corner Reflectors Case.

PubMed

Ao, Dongyang; Li, Yuanhao; Hu, Cheng; Tian, Weiming

2017-12-22

The dihedral corner reflectors are the basic geometric structure of many targets and are the main contributions of radar cross section (RCS) in the synthetic aperture radar (SAR) images. In stealth technologies, the elaborate design of the dihedral corners with different opening angles is a useful approach to reduce the high RCS generated by multiple reflections. As bistatic synthetic aperture sensors have flexible geometric configurations and are sensitive to the dihedral corners with different opening angles, they specially fit for the stealth target detections. In this paper, the scattering characteristic of dihedral corner reflectors is accurately analyzed in bistatic synthetic aperture images. The variation of RCS with the changing opening angle is formulated and the method to design a proper bistatic radar for maximizing the detection capability is provided. Both the results of the theoretical analysis and the experiments show the bistatic SAR could detect the dihedral corners, under a certain bistatic angle which is related to the geometry of target structures.

Structural-electrical coupling optimisation for radiating and scattering performances of active phased array antenna

NASA Astrophysics Data System (ADS)

Wang, Congsi; Wang, Yan; Wang, Zhihai; Wang, Meng; Yuan, Shuai; Wang, Weifeng

2018-04-01

It is well known that calculating and reducing of radar cross section (RCS) of the active phased array antenna (APAA) are both difficult and complicated. It remains unresolved to balance the performance of the radiating and scattering when the RCS is reduced. Therefore, this paper develops a structure and scattering array factor coupling model of APAA based on the phase errors of radiated elements generated by structural distortion and installation error of the array. To obtain the optimal radiating and scattering performance, an integrated optimisation model is built to optimise the installation height of all the radiated elements in normal direction of the array, in which the particle swarm optimisation method is adopted and the gain loss and scattering array factor are selected as the fitness function. The simulation indicates that the proposed coupling model and integrated optimisation method can effectively decrease the RCS and that the necessary radiating performance can be simultaneously guaranteed, which demonstrate an important application value in engineering design and structural evaluation of APAA.

Effect of phase errors in stepped-frequency radar systems

NASA Astrophysics Data System (ADS)

Vanbrundt, H. E.

1988-04-01

Stepped-frequency waveforms are being considered for inverse synthetic aperture radar (ISAR) imaging from ship and airborne platforms and for detailed radar cross section (RCS) measurements of ships and aircraft. These waveforms make it possible to achieve resolutions of 1.0 foot by using existing radar designs and processing technology. One problem not yet fully resolved in using stepped-frequency waveform for ISAR imaging is the deterioration in signal level caused by random frequency error. Random frequency error of the stepped-frequency source results in reduced peak responses and increased null responses. The resulting reduced signal-to-noise ratio is range dependent. Two of the major concerns addressed in this report are radar range limitations for ISAR and the error in calibration for RCS measurements caused by differences in range between a passive reflector used for an RCS reference and the target to be measured. In addressing these concerns, NOSC developed an analysis to assess the tolerable frequency error in terms of resulting power loss in signal power and signal-to-phase noise.

Accurate Analysis of Target Characteristic in Bistatic SAR Images: A Dihedral Corner Reflectors Case

PubMed Central

Ao, Dongyang; Hu, Cheng; Tian, Weiming

2017-01-01

The dihedral corner reflectors are the basic geometric structure of many targets and are the main contributions of radar cross section (RCS) in the synthetic aperture radar (SAR) images. In stealth technologies, the elaborate design of the dihedral corners with different opening angles is a useful approach to reduce the high RCS generated by multiple reflections. As bistatic synthetic aperture sensors have flexible geometric configurations and are sensitive to the dihedral corners with different opening angles, they specially fit for the stealth target detections. In this paper, the scattering characteristic of dihedral corner reflectors is accurately analyzed in bistatic synthetic aperture images. The variation of RCS with the changing opening angle is formulated and the method to design a proper bistatic radar for maximizing the detection capability is provided. Both the results of the theoretical analysis and the experiments show the bistatic SAR could detect the dihedral corners, under a certain bistatic angle which is related to the geometry of target structures. PMID:29271917

An algorithm for automatic target recognition using passive radar and an EKF for estimating aircraft orientation

NASA Astrophysics Data System (ADS)

Ehrman, Lisa M.

2005-07-01

Rather than emitting pulses, passive radar systems rely on "illuminators of opportunity," such as TV and FM radio, to illuminate potential targets. These systems are attractive since they allow receivers to operate without emitting energy, rendering them covert. Until recently, most of the research regarding passive radar has focused on detecting and tracking targets. This dissertation focuses on extending the capabilities of passive radar systems to include automatic target recognition. The target recognition algorithm described in this dissertation uses the radar cross section (RCS) of potential targets, collected over a short period of time, as the key information for target recognition. To make the simulated RCS as accurate as possible, the received signal model accounts for aircraft position and orientation, propagation losses, and antenna gain patterns. An extended Kalman filter (EKF) estimates the target's orientation (and uncertainty in the estimate) from velocity measurements obtained from the passive radar tracker. Coupling the aircraft orientation and state with the known antenna locations permits computation of the incident and observed azimuth and elevation angles. The Fast Illinois Solver Code (FISC) simulates the RCS of potential target classes as a function of these angles. Thus, the approximated incident and observed angles allow the appropriate RCS to be extracted from a database of FISC results. Using this process, the RCS of each aircraft in the target class is simulated as though each is executing the same maneuver as the target detected by the system. Two additional scaling processes are required to transform the RCS into a power profile (magnitude only) simulating the signal in the receiver. First, the RCS is scaled by the Advanced Refractive Effects Prediction System (AREPS) code to account for propagation losses that occur as functions of altitude and range. Then, the Numerical Electromagnetic Code (NEC2) computes the antenna gain pattern, further scaling the RCS. A Rician likelihood model compares the scaled RCS of the illuminated aircraft with those of the potential targets. To improve the robustness of the result, the algorithm jointly optimizes over feasible orientation profiles and target types via dynamic programming.

The design of broadband radar absorbing surfaces

NASA Astrophysics Data System (ADS)

Suk, Go H.

1990-09-01

There has been a growing and widespread interest in radar absorbing material technology. As the name implies, radar absorbing materials or RAM's are coatings whose electric and magnetic properties have been selected to allow the absorption of microwave energy at discrete or broadband frequencies. In military applications low radar cross section (RCS) of a vehicle may be required in order to escape detection while a covert mission is being carried on. These requirements have led to the very low observable or stealth technology that reduces the probability of detection of an aircraft. The design of radar absorbing materials is limited by constraints on the allowable volume and weight of the surface coating, and it is difficult to design a broadband radar absorbing structure in limited volume. This thesis investigates the use of lossy dielectric materials of high dielectric permittivity in multilayer composites for the production of low radar cross section (RCS). The analysis is done by computing the plane wave reflection coefficient at the exterior surface of the composite coating by means of a computer program which selects layer parameters which determine low reflection coefficients for electromagnetic radiation under constraint of limited layer thickness as well as maximum frequency bandwidth.

Signature management of radar returns from wind turbine generators

NASA Astrophysics Data System (ADS)

Tennant, A.; Chambers, B.

2006-04-01

The large radar cross section of wind turbine generator (WTG) blades combined with high tip speeds can produce significant Doppler returns when illuminated by a radar. Normally, an air traffic control radar system will filter out large returns from stationary targets, but the Doppler shifts introduced by the WTG blades are interpreted as moving aircraft that can confuse radar operators and compromise safety. A possible solution to this problem is to incorporate an active layer into the structure of the WTG blades that can be used to dynamically modulate the radar cross section (RCS) of the blade return. The active blade can operate in one of two modes: first the blade RCS can be modulated to provide a Doppler return that is outside the detectable range of the radar receiver system so that it is rejected; a second mode of operation is to introduce specific coding onto the Doppler returns so that they may be uniquely identified and rejected. The active layer used in the system consists of a frequency selective surface controlled by semiconductor diodes and is a development of techniques developed for active radar absorbers. Results of theoretical and experimental work using a 10 GHz Doppler radar and scale-model WTG are presented.

XPATCH: a high-frequency electromagnetic scattering prediction code using shooting and bouncing rays

NASA Astrophysics Data System (ADS)

Hazlett, Michael; Andersh, Dennis J.; Lee, Shung W.; Ling, Hao; Yu, C. L.

1995-06-01

This paper describes an electromagnetic computer prediction code for generating radar cross section (RCS), time domain signatures, and synthetic aperture radar (SAR) images of realistic 3-D vehicles. The vehicle, typically an airplane or a ground vehicle, is represented by a computer-aided design (CAD) file with triangular facets, curved surfaces, or solid geometries. The computer code, XPATCH, based on the shooting and bouncing ray technique, is used to calculate the polarimetric radar return from the vehicles represented by these different CAD files. XPATCH computes the first-bounce physical optics plus the physical theory of diffraction contributions and the multi-bounce ray contributions for complex vehicles with materials. It has been found that the multi-bounce contributions are crucial for many aspect angles of all classes of vehicles. Without the multi-bounce calculations, the radar return is typically 10 to 15 dB too low. Examples of predicted range profiles, SAR imagery, and radar cross sections (RCS) for several different geometries are compared with measured data to demonstrate the quality of the predictions. The comparisons are from the UHF through the Ka frequency ranges. Recent enhancements to XPATCH for MMW applications and target Doppler predictions are also presented.

RCS tests utilize ground-plane effects

NASA Astrophysics Data System (ADS)

Knott, E. F.

1984-03-01

It is noted that the ground effects must be thoroughly understood to attain the proper radar cross section (RCS) configurations for a specific test. If the ground is sufficiently smooth, it acts as a mirror. Ground reflections then serve to enhance the incident field strength. If an asphalt or concrete ground plane has not been constructed, the soil must be kept free of vegetation and must be graded and leveled to exploit the effect. To elucidate the role of the ground plane, the various ways that energy propagates to the target and back are considered. In implementing a ground-plane RCS measurement program, it is important that the target height, antenna height, target range, and radar wavelength be chosen so as to place the target at a peak in the interference pattern. It is pointed out that in order to maximize the received signal, the antenna should be depressed below the bisector of the angle between the direct and indirect paths subtended at the radar receiving antenna. The precise amount of depression depends on the antenna radiation pattern.

Electromagnetic scattering by a uniaxial anisotropic sphere located in an off-axis Bessel beam.

PubMed

Qu, Tan; Wu, Zhen-Sen; Shang, Qing-Chao; Li, Zheng-Jun; Bai, Lu

2013-08-01

Electromagnetic scattering of a zero-order Bessel beam by an anisotropic spherical particle in the off-axis configuration is investigated. Based on the spherical vector wave functions, the expansion expression of the zero-order Bessel beam is derived, and its convergence is numerically discussed in detail. Utilizing the tangential continuity of the electromagnetic fields, the expressions of scattering coefficients are given. The effects of the conical angle of the wave vector components of the zero-order Bessel beam, the ratio of the radius of the sphere to the central spot radius of the zero-order Bessel beam, the shift of the beam waist center position along both the x and y axes, the permittivity and permeability tensor elements, and the loss of the sphere on the radar cross section (RCS) are numerically analyzed. It is revealed that the maximum RCS appears in the conical direction or neighboring direction when the sphere is illuminated by a zero-order Bessel beam. Furthermore, the RCS will decrease and the symmetry is broken with the shift of the beam waist center.

RCS of fundamental scatterers in the HF band by wire-grid modelling

NASA Astrophysics Data System (ADS)

Trueman, C. W.; Kubina, S. J.

To extract the maximum information from the return of a radar target such as an aircraft, the target's scattering properties must be well known. Wire grid modeling allows a detailed representation of the surface of a complex scatterer such as an aircraft, in the frequency range where the aircraft size is comparable to a wavelength. A moment method analysis determines the currents on the wires of the grid including the interactions between all parts of the structure. Wire grid models of fundamental scatterers (plates, strips, cubes, and spheres) of sizes comparable to the wavelength in the 2-30 MHz range are analyzed. The study of the radar cross section (RCS) of wire grids in comparison with measured RCS data helps to establish guidelines for building wire grid models, specifying such parameters as where to locate wires, how short the segments must be, and what radius to use. The guidelines so developed can then be applied to build wire grid models of much more complex bodies such as aircraft with much greater confidence.

Combining the absorptive and radiative loss in metasurfaces for multi-spectral shaping of the electromagnetic scattering.

PubMed

Pan, Wenbo; Huang, Cheng; Pu, Mingbo; Ma, Xiaoliang; Cui, Jianhua; Zhao, Bo; Luo, Xiangang

2016-02-19

The absorptive and radiative losses are two fundamental aspects of the electromagnetic responses, which are widely occurring in many different systems such as waveguides, solar cells, and antennas. Here we proposed a metasurface to realize the control of the absorptive and radiative loss and to reduce the radar cross section (RCS) in multi-frequency bands. The anti-phase gradient and absorptive metasurfaces were designed that consists of metallic square patch and square loop structure inserted with resistors, acting as an phase gradient material in the X and Ku band, while behaving as an absorber in the S band. The simulation and experiment results verified the double-band, wideband and polarization-independent RCS reduction by the absorptive and anti-phase gradient metasurfaces.

Research on metal-plated cellulose nitrate flakes and their infrared / millimeter wave characteristics

NASA Astrophysics Data System (ADS)

Ye, Shu-qin; Zhu, Chen-guang; Wang, Li-hong; Ou'yang, De-hua; Pan, Gong-pei

2016-10-01

Copper-plated and silver-plated cellulose nitrate flakes, which were prepared by using chemical plating technology, were used to jam infrared detector and millimeter-wave radar. It was tested for the conductivity and infrared jamming performance of plating and also the RCS (Radar Cross Section) performance of millimeter-wave radar. Test results showed that the prepared metal-plated cellulose nitrate flakes have obvious conductivity, and infrared total radiation energy of silver plating and copper plating had approximately increased 32% and 21% respectively. Through determination, the millimeter-wave reflecting property and RCS of silver-plated cellulose nitrate flakes were higher than that of copper-plated cellulose nitrate flakes. Therefore, silver-plated cellulose nitrate flakes can be used as an effective infrared / millimeter wave composite jamming material.

High-frequency CAD-based scattering model: SERMAT

NASA Astrophysics Data System (ADS)

Goupil, D.; Boutillier, M.

1991-09-01

Specifications for an industrial radar cross section (RCS) calculation code are given: it must be able to exchange data with many computer aided design (CAD) systems, it must be fast, and it must have powerful graphic tools. Classical physical optics (PO) and equivalent currents (EC) techniques have proven their efficiency on simple objects for a long time. Difficult geometric problems occur when objects with very complex shapes have to be computed. Only a specific geometric code can solve these problems. We have established that, once these problems have been solved: (1) PO and EC give good results on complex objects of large size compared to wavelength; and (2) the implementation of these objects in a software package (SERMAT) allows fast and sufficiently precise domain RCS calculations to meet industry requirements in the domain of stealth.

Rapid decrease of radar cross section of meteor head echo observed by the MU radar

NASA Astrophysics Data System (ADS)

Nakamura, T.; Nishio, M.; Sato, T.; Tsutsumi, S.; Tsuda, T.; Fushimi, K.

The meteor head echo observation using the MU (Middle and Upper atmosphere) radar (46.5M Hz, 1MW), Shigaraki, Japan, was carried out simultaneously with a high sensitive ICCD (Image-intensified CCD) camera observation in November 2001. The time records were synchronized using GPS satellite signals, in order to compare instantaneous radar and optical meteor magnitudes. 26 faint meteors were successfully observed simultaneously by both equipments. Detailed comparison of the time variation of radar echo intensity and absolute optical magnitude showed that the radar scattering cross section is likely to decrease rapidly by 5 - 20 dB without no corresponding magnitude variation in the optical data. From a simple modeling, we concluded that such decrease of RCS (radar cross section ) is probably due to the transition from overdense head echo to underd ense head echo.

An Analysis of the Defense Acquisition Strategy for Unmanned Systems

DTIC Science & Technology

2014-03-01

product service code RAA Rapid Acquisition Authority RCS radar cross section REF Rapid Equipping Force RFID radio frequency identification RDT...commercialization of the radio frequency identification (RFID) chip also provides a useful basis for comparison. WWII served as the proving ground for RFID...companies following the September 11 , 2001 attacks. It is important to note that despite advances in GPS technology and long-range communications

An Analysis of the Defense Acquisition Strategy for Unmanned Systems

DTIC Science & Technology

2013-11-20

Product Service Code RAA Rapid Acquisition Authority RCS Radar Cross Section REF Rapid Equipping Force RFID Radio Frequency Identification RDT...the radio frequency identification (RFID) chip also provides a useful basis for comparison. WWII served as the proving ground for RFID technology...enabling miniaturized Free Space Optical Communications systems capable of scaling across data rates, distances, and platforms and integrating with radio

Effects on RCS of a perfect electromagnetic conductor sphere in the presence of anisotropic plasma layer

NASA Astrophysics Data System (ADS)

Ghaffar, A.; Hussan, M. M.; Illahi, A.; Alkanhal, Majeed A. S.; Ur Rehman, Sajjad; Naz, M. Y.

2018-01-01

Effects on RCS of perfect electromagnetic conductor (PEMC) sphere by coating with anisotropic plasma layer are studied in this paper. The incident, scattered and transmitted electromagnetic fields are expanded in term of spherical vector wave functions using extended classical theory of scattering. Co and cross-polarized scattered field coefficients are obtained at the interface of free space-anisotropic plasma and at anisotropic plasma-PEMC sphere core by scattering matrices method. The presented analytical expressions are general for any perfect conducting sphere (PMC, PEC, or PEMC) with general anisotropic/isotropic material coatings that include plasma and metamaterials. The behavior of the forward and backscattered radar cross section of PEMC sphere with the variation of the magnetic field strength, incident frequency, plasma density, and effective collision frequency for the co-polarized and the cross polarized fields are investigated. It is also observed from the obtained results that anisotropic layer on PEMC sphere shows reciprocal behavior as compared to isotopic plasma layer on PEMC sphere. The comparisons of the numerical results of the presented analytical expressions with available results of some special cases show the correctness of the analysis.

Automation of an RCS (Radar Cross Section) measurement system and its application to investigate the electromagnetic scattering from scale model aircraft canopies

NASA Astrophysics Data System (ADS)

Owens, Scott A.

1989-12-01

The purpose of this study was twofold, the first objective was to complete the development of AFIT's Far-Field Radar Range with a fully automated measurement process. The second objective was to use the facility to investigate the scattering of metallic versus transparent aircraft canopies relative to the scattering of the total aircraft. The approach for the investigation was: (1) to measure scale model aircraft to determine the effect of the RCS of the canopy/cockpit area on the RCS of the total aircraft; and (2) to design and measure a test body which would isolate the canopy/cockpit area from the rest of the aircraft. The result of the work on the first task is a software package called AFIT RCS Measurement Software (ARMS). The successful performance of the far-field range was validated by very favorable comparisons with the Wright Research and Development Center's anechoic chamber. The scale model measurements suggest at most a 5 dB difference between the scattering from the two extreme cases. The test body, however, clearly demonstrated differences up to 20 dB at certain frequencies. This study documents the upper and lower bounds of the subject measurements in an indoor measurement range. The Air Force has expressed interest in steering the investigation to examine materials and/or canopy construction.

Bayesian-MCMC-based parameter estimation of stealth aircraft RCS models

NASA Astrophysics Data System (ADS)

Xia, Wei; Dai, Xiao-Xia; Feng, Yuan

2015-12-01

When modeling a stealth aircraft with low RCS (Radar Cross Section), conventional parameter estimation methods may cause a deviation from the actual distribution, owing to the fact that the characteristic parameters are estimated via directly calculating the statistics of RCS. The Bayesian-Markov Chain Monte Carlo (Bayesian-MCMC) method is introduced herein to estimate the parameters so as to improve the fitting accuracies of fluctuation models. The parameter estimations of the lognormal and the Legendre polynomial models are reformulated in the Bayesian framework. The MCMC algorithm is then adopted to calculate the parameter estimates. Numerical results show that the distribution curves obtained by the proposed method exhibit improved consistence with the actual ones, compared with those fitted by the conventional method. The fitting accuracy could be improved by no less than 25% for both fluctuation models, which implies that the Bayesian-MCMC method might be a good candidate among the optimal parameter estimation methods for stealth aircraft RCS models. Project supported by the National Natural Science Foundation of China (Grant No. 61101173), the National Basic Research Program of China (Grant No. 613206), the National High Technology Research and Development Program of China (Grant No. 2012AA01A308), the State Scholarship Fund by the China Scholarship Council (CSC), and the Oversea Academic Training Funds, and University of Electronic Science and Technology of China (UESTC).

Imaging Ca2+ with a Fluorescent Rhodol.

PubMed

Contractor, Alisha A; Miller, Evan W

2018-01-16

Ca 2+ mediates a host of biochemical and biophysical signaling processes in cells. The development of synthetic, Ca 2+ -sensitive fluorophores has played an instrumental role in our understanding of the temporal and spatial dynamics of Ca 2+ . Coupling Ca 2+ -selective ligands to fluorescent reporters has provided a wealth of excellent indicators that span the visible excitation and emission spectrum and possess Ca 2+ affinities suited to a variety of cellular contexts. One underdeveloped area is the use of hybrid rhodamine/fluorescein fluorophores, or rhodols, in the context of Ca 2+ sensing. Rhodols are bright and photostable and have good two-photon absorption cross sections (σ TPA ), making them excellent candidates for incorporation into Ca 2+ -sensing scaffolds. Here, we present the design, synthesis, and application of rhodol Ca 2+ sensor 1 (RCS-1), a chlorinated pyrrolidine-based rhodol. RCS-1 possesses a Ca 2+ binding constant of 240 nM and a 10-fold turn response to Ca 2+ . RCS-1 effectively absorbs infrared light and has a σ TPA of 76 GM at 840 nm, 3-fold greater than that of its fluorescein-based counterpart. The acetoxy-methyl ester of RCS-1 stains the cytosol of live cells, enabling observation of Ca 2+ fluctuations and cultured neurons using both one- and two-photon illumination. Together, these results demonstrate the utility of rhodol-based scaffolds for Ca 2+ sensing using two-photon illumination in neurons.

A planar near-field scanning technique for bistatic radar cross section measurements

NASA Technical Reports Server (NTRS)

Tuhela-Reuning, S.; Walton, E. K.

1990-01-01

A progress report on the development of a bistatic radar cross section (RCS) measurement range is presented. A technique using one parabolic reflector and a planar scanning probe antenna is analyzed. The field pattern in the test zone is computed using a spatial array of signal sources. It achieved an illumination pattern with 1 dB amplitude and 15 degree phase ripple over the target zone. The required scan plane size is found to be proportional to the size of the desired test target. Scan plane probe sample spacing can be increased beyond the Nyquist lambda/2 limit permitting constant probe sample spacing over a range of frequencies.

Missile Defense in the 21st Century Acquisition Environment: Exploring a BMD-Capable LCS Mission Package

DTIC Science & Technology

2013-09-01

75 Figure 25: Swing Weight Analysis....................................................................................76 Figure 26...AN/SPY-1D radar “can track golf ball-sized targets at ranges in excess of 165 kilometers” (Robinson, 2004). Given the radar cross section (RCS) of a... golf ball (calculated as a simple metallic sphere), it was determined that this would correspond to a maximum detection range beyond the Launch

Gigaflop (billion floating point operations per second) performance for computational electromagnetics

NASA Technical Reports Server (NTRS)

Shankar, V.; Rowell, C.; Hall, W. F.; Mohammadian, A. H.; Schuh, M.; Taylor, K.

1992-01-01

Accurate and rapid evaluation of radar signature for alternative aircraft/store configurations would be of substantial benefit in the evolution of integrated designs that meet radar cross-section (RCS) requirements across the threat spectrum. Finite-volume time domain methods offer the possibility of modeling the whole aircraft, including penetrable regions and stores, at longer wavelengths on today's gigaflop supercomputers and at typical airborne radar wavelengths on the teraflop computers of tomorrow. A structured-grid finite-volume time domain computational fluid dynamics (CFD)-based RCS code has been developed at the Rockwell Science Center, and this code incorporates modeling techniques for general radar absorbing materials and structures. Using this work as a base, the goal of the CFD-based CEM effort is to define, implement and evaluate various code development issues suitable for rapid prototype signature prediction.

A boundary integral method for numerical computation of radar cross section of 3D targets using hybrid BEM/FEM with edge elements

NASA Astrophysics Data System (ADS)

Dodig, H.

2017-11-01

This contribution presents the boundary integral formulation for numerical computation of time-harmonic radar cross section for 3D targets. Method relies on hybrid edge element BEM/FEM to compute near field edge element coefficients that are associated with near electric and magnetic fields at the boundary of the computational domain. Special boundary integral formulation is presented that computes radar cross section directly from these edge element coefficients. Consequently, there is no need for near-to-far field transformation (NTFFT) which is common step in RCS computations. By the end of the paper it is demonstrated that the formulation yields accurate results for canonical models such as spheres, cubes, cones and pyramids. Method has demonstrated accuracy even in the case of dielectrically coated PEC sphere at interior resonance frequency which is common problem for computational electromagnetic codes.

[Molecular cloning and characterization of a novel Clonorchis sinensis antigenic protein containing tandem repeat sequences].

PubMed

Liu, Qian; Xu, Xue-Nian; Zhou, Yan; Cheng, Na; Dong, Yu-Ting; Zheng, Hua-Jun; Zhu, Yong-Qiang; Zhu, Yong-Qiang

2013-08-01

To find and clone new antigen genes from the lambda-ZAP cDNA expression library of adult Clonorchis sinensis, and determine the immunological characteristics of the recombinant proteins. The cDNA expression library of adult C. sinensis was screened by pooled sera of clonorchiasis patients. The sequences of the positive phage clones were compared with the sequences in EST database, and the full-length sequence of the gene (Cs22 gene) was obtained by RT-PCR. cDNA fragments containing 2 and 3 times tandem repeat sequences were generated by jumping PCR. The sequence encoding the mature peptide or the tandem repeat sequence was respectively cloned into the prokaryotic expression vector pET28a (+), and then transformed into E. coli Rosetta DE3 cells for expression. The recombinant proteins (rCs22-2r, rCs22-3r, rCs22M-2r, and rCs22M-3r) were purified by His-bind-resin (Ni-NTA) affinity chromatography. The immunogenicity of rCs22-2r and rCs22-3r was identified by ELISA. To evaluate the immunological diagnostic value of rCs22-2r and rCs22-3r, serum samples from 35 clonorchiasis patients, 31 healthy individuals, 15 schistosomiasis patients, 15 paragonimiasis westermani patients and 13 cysticercosis patients were examined by ELISA. To locate antigenic determinants, the pooled sera of clonorchiasis patients and healthy persons were analyzed for specific antibodies by ELISA with recombinant protein rCs22M-2r and rCs22M-3r containing the tandem repeat sequences. The full-length sequence of Cs22 antigen gene of C. sinensis was obtained. It contained 13 times tandem repeat sequences of EQQDGDEEGMGGDGGRGKEKGKVEGEDGAGEQKEQA. Bioinformatics analysis indicated that the protein (Cs22) belonged to GPI-anchored proteins family. The recombinant proteins rCs22-2r and rCs22-3r showed a certain level of immunogenicity. The positive rate by ELISA coated with the purified PrCs22-2r and PrCs22-3r for sera of clonorchiasis patients both were 45.7% (16/35), and 3.2% (1/31) for those of healthy persons. There was no cross reaction with sera of schistosomiasis and cysticercosis patients. The cross reaction with sera of paragonimiasis westermani patients was 1/15. The recombinant proteins rCs22M-2r and rCs22M-3r which only contained tandem repeats were specifically recognized by pooled sera of clonorchiasis patients. The Cs22 antigen gene of Clonorchis sinensis is obtained, and the recombinant proteins have certain diagnostic value. The antigenic determinant is located in tandem repeat sequences.

Distributed ISAR Subimage Fusion of Nonuniform Rotating Target Based on Matching Fourier Transform.

PubMed

Li, Yuanyuan; Fu, Yaowen; Zhang, Wenpeng

2018-06-04

In real applications, the image quality of the conventional monostatic Inverse Synthetic Aperture Radar (ISAR) for the maneuvering target is subject to the strong fluctuation of Radar Cross Section (RCS), as the target aspect varies enormously. Meanwhile, the maneuvering target introduces nonuniform rotation after translation motion compensation which degrades the imaging performance of the conventional Fourier Transform (FT)-based method in the cross-range dimension. In this paper, a method which combines the distributed ISAR technique and the Matching Fourier Transform (MFT) is proposed to overcome these problems. Firstly, according to the characteristics of the distributed ISAR, the multiple channel echoes of the nonuniform rotation target from different observation angles can be acquired. Then, by applying the MFT to the echo of each channel, the defocused problem of nonuniform rotation target which is inevitable by using the FT-based imaging method can be avoided. Finally, after preprocessing, scaling and rotation of all subimages, the noncoherent fusion image containing all the RCS information in all channels can be obtained. The accumulation coefficients of all subimages are calculated adaptively according to the their image qualities. Simulation and experimental data are used to validate the effectiveness of the proposed approach, and fusion image with improved recognizability can be obtained. Therefore, by using the distributed ISAR technique and MFT, subimages of high-maneuvering target from different observation angles can be obtained. Meanwhile, by employing the adaptive subimage fusion method, the RCS fluctuation can be alleviated and more recognizable final image can be obtained.

Ultra-wideband, Wide Angle and Polarization-insensitive Specular Reflection Reduction by Metasurface based on Parameter-adjustable Meta-Atoms

PubMed Central

Su, Jianxun; Lu, Yao; Zhang, Hui; Li, Zengrui; (Lamar) Yang, Yaoqing; Che, Yongxing; Qi, Kainan

2017-01-01

In this paper, an ultra-wideband, wide angle and polarization-insensitive metasurface is designed, fabricated, and characterized for suppressing the specular electromagnetic wave reflection or backward radar cross section (RCS). Square ring structure is chosen as the basic meta-atoms. A new physical mechanism based on size adjustment of the basic meta-atoms is proposed for ultra-wideband manipulation of electromagnetic (EM) waves. Based on hybrid array pattern synthesis (APS) and particle swarm optimization (PSO) algorithm, the selection and distribution of the basic meta-atoms are optimized simultaneously to obtain the ultra-wideband diffusion scattering patterns. The metasurface can achieve an excellent RCS reduction in an ultra-wide frequency range under x- and y-polarized normal incidences. The new proposed mechanism greatly extends the bandwidth of RCS reduction. The simulation and experiment results show the metasurface can achieve ultra-wideband and polarization-insensitive specular reflection reduction for both normal and wide-angle incidences. The proposed methodology opens up a new route for realizing ultra-wideband diffusion scattering of EM wave, which is important for stealth and other microwave applications in the future. PMID:28181593

Ultra-wideband, Wide Angle and Polarization-insensitive Specular Reflection Reduction by Metasurface based on Parameter-adjustable Meta-Atoms.

PubMed

Su, Jianxun; Lu, Yao; Zhang, Hui; Li, Zengrui; Lamar Yang, Yaoqing; Che, Yongxing; Qi, Kainan

2017-02-09

In this paper, an ultra-wideband, wide angle and polarization-insensitive metasurface is designed, fabricated, and characterized for suppressing the specular electromagnetic wave reflection or backward radar cross section (RCS). Square ring structure is chosen as the basic meta-atoms. A new physical mechanism based on size adjustment of the basic meta-atoms is proposed for ultra-wideband manipulation of electromagnetic (EM) waves. Based on hybrid array pattern synthesis (APS) and particle swarm optimization (PSO) algorithm, the selection and distribution of the basic meta-atoms are optimized simultaneously to obtain the ultra-wideband diffusion scattering patterns. The metasurface can achieve an excellent RCS reduction in an ultra-wide frequency range under x- and y-polarized normal incidences. The new proposed mechanism greatly extends the bandwidth of RCS reduction. The simulation and experiment results show the metasurface can achieve ultra-wideband and polarization-insensitive specular reflection reduction for both normal and wide-angle incidences. The proposed methodology opens up a new route for realizing ultra-wideband diffusion scattering of EM wave, which is important for stealth and other microwave applications in the future.

Fluctuations in Conjunction Miss Distance Projections as Time Approaches Time of Closest Approach

NASA Technical Reports Server (NTRS)

Christian, John A., III

2005-01-01

A responsibility of the Trajectory Operations Officer is to ensure that the International Space Station (ISS) avoids colliding with debris. United States Space Command (USSPACECOM) tracks and catalogs a portion of the debris in Earth orbit, but only objects with a perigee less than 600 km and a radar cross section (RCS) greater than 10 cm-objects that, in fact, represent only a small fraction of the objects in Earth orbit. To accommodate for this, the ISS uses shielding to protect against collisions with smaller objects. This study provides a better understanding of how quickly, and to what degree, USSPACECOM projections tend to converge to the final, true miss distance. The information included is formulated to better predict the behavior of miss distance data during real-time operations. It was determined that the driving components, in order of impact on miss distance fluctuations, are energy dissipation rate (EDR), RCS, and inclination. Data used in this analysis, calculations made, and conclusions drawn are stored in Microsoft Excel log sheets. A separate log sheet, created for each conjunction, contains information such as predicted miss distances, apogee and perigee of debris orbit, EDR, RCS, inclination, tracks and observations, statistical data, and other evaluation/orbital parameters.

Analysis of the radar cross-section (RCS) of aircraft vortices

NASA Astrophysics Data System (ADS)

Shariff, Karim; Wray, Alan

1999-11-01

Radar has been proposed as one way to track wake vortices to reduce aircraft spacing. Radar echoes from aircraft wakes are usually interpreted qualitatively using Tatarski's theory of scattering by isotropic atmospheric turbulence. The present work predicts RCS by (1) Keeping the weak scattering approximation but dropping the assumptions of a far-field and a uniform incident wave, neither of which is generally valid for a coherent wake (2) Considering three simple mechanisms for the structure and magnitude of refractive index variations: (i) Radial density gradient in each vortex (ii) Adiabatic transport of atmospheric fluid in the oval surrounding the vortices (iii) 3D fluctuations in the vortex cores. For mechanism (ii) the predictions agree with available data. However, the predictions have a cut-off away from normal incidence which is not present in the measurements due possibly to 3D fluctuations in the oval. The reflectivity of mechanism (i) is comparable but cuts-off at frequencies lower than those considered in the experiment. Finally, we suggest that hot engine exhaust could increase RCS by 40 db and reveal vortex circulation, provided its mixing is prevented in the laminar vortices.

Application of AWE Along with a Combined FEM/MoM Technique to Compute RCS of a Cavity-Backed Aperture in an Infinite Ground Plane Over a Frequency Range

NASA Technical Reports Server (NTRS)

Reddy, C.J.; Deshpande, M.D.

1997-01-01

A hybrid Finite Element Method (FEM)/Method of Moments (MoM) technique in conjunction with the Asymptotic Waveform Evaluation (AWE) technique is applied to obtain radar cross section (RCS) of a cavity-backed aperture in an infinite ground plane over a frequency range. The hybrid FEM/MoM technique when applied to the cavity-backed aperture results in an integro-differential equation with electric field as the unknown variable, the electric field obtained from the solution of the integro-differential equation is expanded in Taylor series. The coefficients of the Taylor series are obtained using the frequency derivatives of the integro-differential equation formed by the hybrid FEM/MoM technique. The series is then matched via the Pade approximation to a rational polynomial, which can be used to extrapolate the electric field over a frequency range. The RCS of the cavity-backed aperture is calculated using the electric field at different frequencies. Numerical results for a rectangular cavity, a circular cavity, and a material filled cavity are presented over a frequency range. Good agreement between AWE and the exact solution over the frequency range is obtained.

Two-Way Pattern Design for Distributed Subarray Antennas

DTIC Science & Technology

2012-09-01

GUI Graphical User Interface HPBW Half-power Beamwidth MFR Multifunction Radar RCS Radar Cross Section RRE Radar Range Equation...The Aegis ships in the US Navy use phased arrays for the AN/SPY-1 multifunction radar ( MFR ) [2]. The phased array for the AN/SPY-1 radar is shown in...arrays. This is a challenge for design of antenna apertures for shipboard radar systems. One design approach is to use multi-function subarray

Multistep Cylindrical Structure Analysis at Normal Incidence Based on Water-Substrate Broadband Metamaterial Absorbers

NASA Astrophysics Data System (ADS)

Fang, Chonghua

2018-01-01

A new multistep cylindrical structure based on water-substrate broadband metamaterial absorbers is designed to reduce the traditional radar cross-section (RCS) of a rod-shaped object. The proposed configuration consists of two distinct parts. One of these components is formed by a four-step cylindrical metal structure, whereas the other one is formed by a new water-substrate broadband metamaterial absorber. The designed structure can significantly reduce the radar cross section more than 10 dB from 4.58 to 18.42 GHz which is the 86.5 % bandwidth of from C-band to 20 GHz. The results of measurement show reasonably good accordance with the simulated ones, which verifies the ability and effect of the proposed design.

High Power Microwave Emission of Large and Small Orbit Gyrotron Devices in Rectangular Interaction Structures

NASA Astrophysics Data System (ADS)

Hochman, J. M.; Gilgenbach, R. M.; Jaynes, R. L.; Rintamaki, J. I.; Luginsland, J. W.; Lau, Y. Y.; Spencer, T. A.

1996-11-01

Experiments utilize large and small orbit e-beam gyrotron devices in a rectangular-cross-section (RCS) gyrotron. This device is being explored to examine polarization control. Other research issues include pulse shortening, and mode competition. MELBA generates electron beams with parameters of: -800kV, 1-10kA diode current, and 0.5-1.0 μ sec pulselengths. The small orbit gyrotron device is converted to a large orbit experiment by running MELBA's annular electron beam through a magnetic cusp. Initial experiments showed an increase in beam alpha (V_perp/V_par) of a factor of ~ 4 between small and large orbit devices. Experimental results from the RCS gyrotron will be compared for large-orbit and small-orbit electron beams. Beam transport data and frequency measurements will be presented. Computer modeling utilizing the MAGIC and E-gun codes will be shown.

A physical optics/equivalent currents model for the RCS of trihedral corner reflectors

NASA Technical Reports Server (NTRS)

Balanis, Constantine A.; Polycarpou, Anastasis C.

1993-01-01

The scattering in the interior regions of both square and triangular trihedral corner reflectors is examined. The theoretical model presented combines geometrical and physical optics (GO and PO), used to account for reflection terms, with equivalent edge currents (EEC), used to account for first-order diffractions from the edges. First-order, second-order, and third-order reflection terms are included. Calculating the first-order reflection terms involves integrating over the entire surface of the illuminated plate. Calculating the second- and third-order reflection terms, however, is much more difficult because the illuminated area is an arbitrary polygon whose shape is dependent upon the incident angles. The method for determining the area of integration is detailed. Extensive comparisons between the high-frequency model, Finite-Difference Time-Domain (FDTD) and experimental data are used for validation of the radar cross section (RCS) of both square and triangular trihedral reflectors.

Scattering of targets over layered half space using a semi-analytic method in conjunction with FDTD algorithm.

PubMed

Cao, Le; Wei, Bing

2014-08-25

Finite-difference time-domain (FDTD) algorithm with a new method of plane wave excitation is used to investigate the RCS (Radar Cross Section) characteristics of targets over layered half space. Compare with the traditional excitation plane wave method, the calculation memory and time requirement is greatly decreased. The FDTD calculation is performed with a plane wave incidence, and the RCS of far field is obtained by extrapolating the currently calculated data on the output boundary. However, methods available for extrapolating have to evaluate the half space Green function. In this paper, a new method which avoids using the complex and time-consuming half space Green function is proposed. Numerical results show that this method is in good agreement with classic algorithm and it can be used in the fast calculation of scattering and radiation of targets over layered half space.

Determination of antennae patterns and radar reflection characteristics of aircraft

NASA Astrophysics Data System (ADS)

Bothe, H.; MacDonald, D.; Pool, A.

1986-05-01

The different types of aircraft antennas, their radiation characteristics and their preferred siting on the airframe are described. Emphasis is placed on the various methods for determining aircraft antenna radiation patterns (ARP) and advantages, disadvantages and limitations of each method are indicated. Mathematical modelling, model measurements and in-flight measurements in conjunction with the applied flight test techniques are included. Examples of practical results are given. Methods of determining aircraft radar characteristics are also described, indicating advantages, disadvantages and limitations of each method. Relevant fundamentals of radar theory are included only as necessary to appreciation of the real meaning of radar cross section (RCS) and angular glint. The measuring methods included are dynamic full-scale, static full-scale, sub-scale optical, ultrasonic and radio modelling. References are made to RCS measuring facilities in the USA and Europe and the UK Radio Modelling Facility is used extensively to exemplify the sub scale technique.

Radar cross section studies/compact range research

NASA Technical Reports Server (NTRS)

Burnside, W. D.; Dominek, A. K.; Gupta, I. J.; Newman, E. H.; Pathak, P. H.; Peters, L., Jr.

1989-01-01

Achievements in advancing the state-of-the-art in the measurement, control, and analysis of electromagnetic scattering from general aerodynamic targets are summarized. The major topics associated with this study include: (1) electromagnetic scattering analysis; (2) indoor scattering measurement systems; (3) RCS control; (4) waveform processing techniques; (5) material scattering and design studies; (6) design and evaluation of standard targets; and (7) antenna studies. Progress in each of these areas is reported and related publications are listed.

First upper limits on the radar cross section of cosmic-ray induced extensive air showers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abbasi, R. U.; Abe, M.; Abou Bakr Othman, M.

TARA (Telescope Array Radar) is a cosmic ray radar detection experiment colocated with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. Furthermore, the TARA detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting antenna which broadcasts the radar carrier over the SD array and within the FD field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data since 2013 with the primary goal of observing the radar signatures of extensive air showers (EAS). Simulations indicate that echoes are expected to be short in durationmore » (~10 µs) and exhibit rapidly changing frequency, with rates on the order 1 MHz/µs. The EAS radar cross-section (RCS) is currently unknown although it is the subject of over 70 years of speculation. One novel signal search technique is described in which the expected radar echo of a particular air shower is used as a matched filter template and compared to waveforms obtained by triggering the radar DAQ using the Telescope Array fluorescence detector. No evidence for the scattering of radio frequency radiation by EAS is obtained to date. Finally, we report the first quantitative RCS upper limits using EAS that triggered the Telescope Array Fluorescence Detector.« less

First upper limits on the radar cross section of cosmic-ray induced extensive air showers

DOE PAGES

Abbasi, R. U.; Abe, M.; Abou Bakr Othman, M.; ...

2016-11-19

TARA (Telescope Array Radar) is a cosmic ray radar detection experiment colocated with Telescope Array, the conventional surface scintillation detector (SD) and fluorescence telescope detector (FD) near Delta, Utah, U.S.A. Furthermore, the TARA detector combines a 40 kW, 54.1 MHz VHF transmitter and high-gain transmitting antenna which broadcasts the radar carrier over the SD array and within the FD field of view, towards a 250 MS/s DAQ receiver. TARA has been collecting data since 2013 with the primary goal of observing the radar signatures of extensive air showers (EAS). Simulations indicate that echoes are expected to be short in durationmore » (~10 µs) and exhibit rapidly changing frequency, with rates on the order 1 MHz/µs. The EAS radar cross-section (RCS) is currently unknown although it is the subject of over 70 years of speculation. One novel signal search technique is described in which the expected radar echo of a particular air shower is used as a matched filter template and compared to waveforms obtained by triggering the radar DAQ using the Telescope Array fluorescence detector. No evidence for the scattering of radio frequency radiation by EAS is obtained to date. Finally, we report the first quantitative RCS upper limits using EAS that triggered the Telescope Array Fluorescence Detector.« less

Design of transmission-type phase holograms for a compact radar-cross-section measurement range at 650 GHz.

PubMed

Noponen, Eero; Tamminen, Aleksi; Vaaja, Matti

2007-07-10

A design formalism is presented for transmission-type phase holograms for use in a submillimeter-wave compact radar-cross-section (RCS) measurement range. The design method is based on rigorous electromagnetic grating theory combined with conventional hologram synthesis. Hologram structures consisting of a curved groove pattern on a 320 mmx280 mm Teflon plate are designed to transform an incoming spherical wave at 650 GHz into an output wave generating a 100 mm diameter planar field region (quiet zone) at a distance of 1 m. The reconstructed quiet-zone field is evaluated by a numerical simulation method. The uniformity of the quiet-zone field is further improved by reoptimizing the goal field. Measurement results are given for a test hologram fabricated on Teflon.

Multistatic GNSS Receiver Array for Passive Air Surveillance

NASA Astrophysics Data System (ADS)

Wachtl, Stefan; Koch, Volker; Westphal, Robert; Schmidt, Lorenz-Peter

2016-03-01

The performance of a passive air surveillance sensor based on Global Navigation Satellite Systems (GNSS) is mainly limited by the receiver noise efficiency, the achievable signal processing gain and the radar cross section (RCS) of an airplane. For surveillance applications large detection ranges as well as a high probability of detection are crucial parameters. Due to the very low GNSS signal powers received on the earth's surface, high radar cross sections are mandatory to achieve detection ranges for airplanes at some kilometers distance. This paper will discuss a multistatic transmitter and receiver arrangement, which is indispensable to get a reasonable detection rate with respect to a hemispheric field of view. The strong performance dependency of such a sensor on the number of transmitters and receivers will be shown by means of some exemplary simulation results.

Scattering by rotationally symmetric anisotropic spheres: potential formulation and parametric studies.

PubMed

Qiu, Cheng-Wei; Li, Le-Wei; Yeo, Tat-Soon; Zouhdi, Saïd

2007-02-01

Vector potential formulation and parametric studies of electromagnetic scattering problems of a sphere characterized by the rotationally symmetric anisotropy are studied. Both epsilon and mu tensors are considered herein, and four elementary parameters are utilized to specify the material properties in the structure. The field representations can be obtained in terms of two potentials, and both TE (TM) modes (with respect to r) inside (outside) the sphere can be derived and expressed in terms of a series of fractional-order (in a real or complex number) Ricatti-Bessel functions. The effects due to either electric anisotropy ratio (Ae=epsilont/epsilonr) or magnetic anisotropy ratio (Am=mut/mur) on the radar cross section (RCS) are considered, and the hybrid effects due to both Ae and Am are also examined extensively. It is found that the material anisotropy affects significantly the scattering behaviors of three-dimensional dielectric objects. For absorbing spheres, however, the Ae or Am no longer plays a significant role as in lossless dielectric spheres and the anisotropic dependence of RCS values is found to be predictable. The hybrid effects of Ae and Am are considered for absorbing spheres as well, but it is found that the RCS can be greatly reduced by controlling the material parameters. Details of the theoretical treatment and numerical results are presented.

Millimeter wave scattering characteristics and radar cross section measurements of common roadway objects

NASA Astrophysics Data System (ADS)

Zoratti, Paul K.; Gilbert, R. Kent; Majewski, Ronald; Ference, Jack

1995-12-01

Development of automotive collision warning systems has progressed rapidly over the past several years. A key enabling technology for these systems is millimeter-wave radar. This paper addresses a very critical millimeter-wave radar sensing issue for automotive radar, namely the scattering characteristics of common roadway objects such as vehicles, roadsigns, and bridge overpass structures. The data presented in this paper were collected on ERIM's Fine Resolution Radar Imaging Rotary Platform Facility and processed with ERIM's image processing tools. The value of this approach is that it provides system developers with a 2D radar image from which information about individual point scatterers `within a single target' can be extracted. This information on scattering characteristics will be utilized to refine threat assessment processing algorithms and automotive radar hardware configurations. (1) By evaluating the scattering characteristics identified in the radar image, radar signatures as a function of aspect angle for common roadway objects can be established. These signatures will aid in the refinement of threat assessment processing algorithms. (2) Utilizing ERIM's image manipulation tools, total RCS and RCS as a function of range and azimuth can be extracted from the radar image data. This RCS information will be essential in defining the operational envelope (e.g. dynamic range) within which any radar sensor hardware must be designed.

Self-efficacy reduces the impact of social isolation on medical student's rural career intent.

PubMed

Isaac, Vivian; Pit, Sabrina Winona; McLachlan, Craig S

2018-03-20

Social isolation in medical students is a subjective experience that may influence medical career decision making. Rural self-efficacy has been shown to influence rural career intentions following a rural clinical placement, however its impact on social isolation during a rural clinical placement has not been previously modeled. The objective of this study is to explore whether self-perception of social isolation is associated with rural career intent in rural medical students. Secondly, to determine whether self-efficacy influences the association between social isolation and rural career intent. 2015 data, from a cross-sectional survey of the National Federation of Rural Australian Medical Educators (FRAME) study. Among 619 medical students attending rural clinical schools (RCS), rural career intent was assessed. This included intended rural location for either postgraduate medical specialist or generalist training or completion of that training. Self-efficacy beliefs in rural medical practice were based on a validated scale consisting of six questions. Social isolation was measured asking students whether they felt socially isolated during their RCS placement. 31.3% of surveyed students self-reported feeling socially isolated during their rural placement. Social isolation was associated with reduced rural career intent after controlling for gender, rural background, RCS preference, RCS support and wellbeing. In step-wise logistic regression the association between social isolation and rural intent disappeared with the inclusion of rural self-efficacy. Social isolation during a rural clinical placement is commonly reported and is shown to reduce rural career intent. High levels of rural clinical self-efficacy reduce the effects of social isolation on future rural workforce intentions.

Gender adjustment or stratification in discerning upper extremity musculoskeletal disorder risk?

PubMed

Silverstein, Barbara; Fan, Z Joyce; Smith, Caroline K; Bao, Stephen; Howard, Ninica; Spielholz, Peregrin; Bonauto, David; Viikari-Juntura, Eira

2009-03-01

The aim was to explore whether "adjustment" for gender masks important exposure differences between men and women in a study of rotator cuff syndrome (RCS) and carpal tunnel syndrome (CTS) and work exposures. This cross-sectional study of 733 subjects in 12 health care and manufacturing workplaces used detailed individual health and work exposure assessment methods. Multiple logistic regression analysis was used to compare gender stratified and adjusted models. Prevalence of RCS and CTS among women was 7.1% and 11.3% respectively, and among men 7.8% and 6.4%. In adjusted (gender, age, body mass index) multivariate analyses of RCS and CTS, gender was not statistically significantly different. For RCS, upper arm flexion >/=45 degrees and forceful pinch increased the odds in the gender-adjusted model (OR 2.66, 95% CI 1.26-5.59) but primarily among women in the stratified analysis (OR 6.68, 95% CI 1.81-24.66 versus OR 1.45, 95% CI 0.53-4.00). For CTS, wrist radial/ulnar deviation >/=4% time and lifting >/=4.5kg >3% time, the adjusted OR was higher for women (OR 4.85, 95% CI 2.12-11.11) and in the gender stratified analyses, the odds were increased for both genders (women OR 5.18, 95% CI 1.70-15.81 and men OR 3.63, 95% CI 1.08-12.18). Gender differences in response to physical work exposures may reflect gender segregation in work and potential differences in pinch and lifting capacity. Reduction in these exposures may reduce prevalence of upper extremity disorders for all workers.

Radar Cross Section Studies/Compact Range Research

NASA Technical Reports Server (NTRS)

Burnside, W. D.; Dominek, A. K.; Gupta, I. J.; Newman, E. H.; Pathak, P. H.; Peters, L., Jr.

1988-01-01

A summary is given of the achievements of NASA Grant NsG-1613 by Ohio State University from May 1, 1987 to April 30, 1988. The major topics covered are as follows: (1) electromagnetic scattering analysis; (2) indoor scattering measurement systems; (3) RCS control; (4) waveform processing techniques; (5) material scattering and design studies; (6) design and evaluation of design studies; and (7) antenna studies. Major progress has been made in each of these areas as verified by the numerous publications produced.

Treemap Visualization for Space Situational Awareness

DTIC Science & Technology

2015-10-18

virtually any display like a table with textual metadata, a hyperlink to a web page, or another treemap. Animation can be used to “explode” the tile to...release; distribution unlimited. 88ABW Cleared 07/30/2015; 88ABW-2015-3828. In Fig. 7 shown below, we have chosen to select “Size By Radar Cross...Section ( RCS )”. We’re still looking at the same Unclassified Space Catalog scenario, but we’ve simply chosen a different “Size by” option, and the view

Association between self-efficacy, career interest and rural career intent in Australian medical students with rural clinical school experience

PubMed Central

Isaac, Vivian; Walters, Lucie; McLachlan, Craig S

2015-01-01

Objectives To investigate medical student's self-efficacy at the time of finishing their rural clinical school (RCS) placement and factors associated with self-efficacy. Secondary aims are to explore whether interest levels or self-efficacy are associated with rural or remote career intentions. Design, setting and participants A cross-sectional study of medical students who had completed their RCS term in 17 Australian universities. Data were derived from the 2013 Federation of Rural Australian Medical Educators (FRAME) evaluation survey. Questionnaire responses were analysed from 653 medical students from regional Australia. All 732 students who completed their RCS term in 2013 were invited to participate. Primary and secondary outcome measures Rural self-efficacy: Six questions to measure self-efficacy beliefs in rural medical practice, based on the sources of self-efficacy described by Bandura. Rural career intention: Students were asked to identify their preferred location for future practice. The options were, Capital or Major City; Inner regional city or large town; Smaller town and very remote area. Results Questionnaire responses were analysed from 653 medical students from regional Australia (response rate 89.2%). 83.8% of all students recalled an increase in their interest levels for rural medicine as a result of their RCS experience. Actual career intention to work in a regional area or rural area was 60.2%. Bivariate analyses showed female gender (p=0.003), rural background (p<0.001), an RCS preference for clinical training (p<0.001) and general practice intentions (p=0.004) were factors associated with higher levels of self-efficacy. Logistic regression analyses showed that self-efficacy was independently associated with increased interest in rural medicine (OR 1.4 (95% CI 1.3 to 1.5)) and rural career intent (OR 1.2 (95% CI 1.1 to 1.3)). (Model included gender, rural background, preference for RCS, generalist intent, rural practice interest and self-efficacy). Conclusions Self-efficacy is associated with increased interest levels for rural medicine and rural medical career intent. PMID:26671960

Association between self-efficacy, career interest and rural career intent in Australian medical students with rural clinical school experience.

PubMed

Isaac, Vivian; Walters, Lucie; McLachlan, Craig S

2015-12-15

To investigate medical student's self-efficacy at the time of finishing their rural clinical school (RCS) placement and factors associated with self-efficacy. Secondary aims are to explore whether interest levels or self-efficacy are associated with rural or remote career intentions. A cross-sectional study of medical students who had completed their RCS term in 17 Australian universities. Data were derived from the 2013 Federation of Rural Australian Medical Educators (FRAME) evaluation survey. Questionnaire responses were analysed from 653 medical students from regional Australia. All 732 students who completed their RCS term in 2013 were invited to participate. Rural self-efficacy: Six questions to measure self-efficacy beliefs in rural medical practice, based on the sources of self-efficacy described by Bandura. Rural career intention: Students were asked to identify their preferred location for future practice. The options were, Capital or Major City; Inner regional city or large town; Smaller town and very remote area. Questionnaire responses were analysed from 653 medical students from regional Australia (response rate 89.2%). 83.8% of all students recalled an increase in their interest levels for rural medicine as a result of their RCS experience. Actual career intention to work in a regional area or rural area was 60.2%. Bivariate analyses showed female gender (p=0.003), rural background (p<0.001), an RCS preference for clinical training (p<0.001) and general practice intentions (p=0.004) were factors associated with higher levels of self-efficacy. Logistic regression analyses showed that self-efficacy was independently associated with increased interest in rural medicine (OR 1.4 (95% CI 1.3 to 1.5)) and rural career intent (OR 1.2 (95% CI 1.1 to 1.3)). (Model included gender, rural background, preference for RCS, generalist intent, rural practice interest and self-efficacy). Self-efficacy is associated with increased interest levels for rural medicine and rural medical career intent. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Medical service use and usual care of common shoulder disorders in Korea: a cross-sectional study using the Health Insurance Review and Assessment Service National Patient Sample

PubMed Central

Joo, Hwansoo; Lee, Yoon Jae; Shin, Joon-Shik; Lee, Jinho; Kim, Me-riong; Koh, Wonil; Park, Yeoncheol; Song, Yun Kyung; Cho, Jae-Heung

2017-01-01

Objectives This study examined National Health Insurance claims data to investigate the epidemiology of shoulder disorders in Korea. Detailed information on medical services and related costs was assessed by major shoulder disorder category. Design and setting The 2014 National Patient Sample dataset provided by the Health Insurance Review and Assessment Service was analysed. Among shoulder-related diagnosis codes, adhesive capsulitis of the shoulder (ACS), rotator cuff syndrome (RCS) and shoulder impingement syndrome (SIS) categories were of highest prevalence. Sociodemographic characteristics and medical service use, frequency and medical costs regarding common shoulder disorders were evaluated. Results The majority of patients with shoulder disorder received ambulatory care (97%). Total and per-patient expenses were highest in patients with RCS. The number of inpatients with RCS was more than twice that of the other two groups, and patients with RCS were more likely to receive surgical management compared with patients with ACS and SIS. Prevalence of shoulder disorders was highest among subjects in their 50s for all three groups. Primary care physicians treated 75.80% of patients with ACS, 56.99% of patients with RCS and 48.06% of patients with SIS, respectively, outlining the difference in medical institution usage patterns. In all three groups, the highest proportion of patients visited orthopaedic surgeons out of medical departments. In the ACS and SIS groups, cost of visits (consultations) took up the largest part of total expenses at 32.30% and 18.88%, respectively, while cost of procedure/surgery constituted the largest portion in patients with RCS (37.77%). The usage proportion of subcutaneous or intramuscular and intra-articular injections ranged between 20% and 30% for outpatients in all three groups. Conclusions Medical service use, frequency and cost distributions relating to major shoulder disorders in Korea were assessed using nationwide claims data. These findings are expected to aid policy-makers as well as researchers and practitioners as basic healthcare data. PMID:28706100

ON-retinal bipolar cell survival in RCS rats.

PubMed

Zhang, Chen Xing; Yin, Zheng Qin; Chen, Li-Feng; Weng, Chuang-Huang; Zeng, Yu-Xiao

2010-11-01

In retinitis pigmentosa (RP), the slow and progressive death of inner retinal neurons is thought to be inevitable after the death of photoreceptors. However, even in the advanced stage of RP, all inner retinal neurons are not completely lost. The morphological and electrophysiological modifications in ON-retinal bipolar cells (ON-RBCs) of Royal College of Surgeons (RCS) rats (RCS-ON-RBCs) were investigated to elucidate the mechanisms of survival of RCS-ON-RBCs in RP. Control (CTR) and RCS rats were divided into age groups according to postnatal stage: postnatal day 21 (Pn21d), postnatal day 30 (Pn30d), postnatal day 60 (Pn60d), and postnatal day 90 (Pn90d). Lucifer yellow staining of single ON-RBCs and double-immunofluorescence of the retinal frozen sections were used to detect the morphological modifications and loss of RCS-ON-RBCs in different retinal regions. The whole-cell patch clamping technique was used to record the electrophysiological properties of ON-RBCs. There was a significant loss of RCS-ON-RBCs compared with CTR (p < 0.01) at Pn60d. Loss of the RCS-ON-RBCs differed by region. From Pn60d onwards, the loss was more severe in the peripheral retinal regions (p < 0.01). From Pn21d, the ectopic neurites from the RCS-ON-RBCs reached the outer and inner nuclear layers. At Pn60d, terminal branches of RCS-ON-RBCs axons vanished and ectopic neurites from the RCS-ON-RBCs became entwined. The resting membrane potential, input resistance and outward membrane current amplitude of RCS-ON-RBCs were significantly higher than those of the ON-RBCs of CTR rats at Pn60d (p < 0.05). Our results indicate that more RCS-ON-RBCs survived in the central retinal area near cone clusters, potentially as a result of ectopic neuritis. Meanwhile the surviving RCS-ON-RBCs remained immature and had no normal electrophysiological characteristics.

Differences in the use of spirometry between rural and urban primary care centers in Spain.

PubMed

Márquez-Martín, Eduardo; Soriano, Joan B; Rubio, Myriam Calle; Lopez-Campos, Jose Luis

2015-01-01

The aim of this study is to evaluate the ability and practice of spirometry, training of technicians, and spirometry features in primary care centers in Spain, evaluating those located in a rural environment against those in urban areas. An observational cross-sectional study was conducted in 2012 by a telephone survey in 970 primary health care centers in Spain. The centers were divided into rural or urban depending on the catchment population. The survey contacted technicians in charge of spirometry and consisted of 36 questions related to the test that included the following topics: center resources, training doctors and technicians, using the spirometer, bronchodilator test, and the availability of spirometry and maintenance. Although the sample size was achieved in both settings, rural centers (RCs) gave a lower response rate than urban centers (UCs). The number of centers without spirometry in rural areas doubled those in the urban areas. Most centers had between one and two spirometers. However, the number of spirometry tests per week was significantly lower in RCs than in UCs (4 [4.1%] vs 6.9 [5.7%], P<0.01). The availability of a specific schedule for conducting spirometries was higher in RCs than in UCs (209 [73.0%] vs 207 [64.2%], P=0.003). RCs were more satisfied with the spirometries (7.8 vs 7.6, P=0.019) and received more training course for interpreting spirometry (41.0% vs 33.2%, P=0.004). The performance of the bronchodilator test showed a homogeneous measure in different ways. The spirometer type and the reference values were unknown to the majority of respondents. This study shows the differences between primary care RCs and UCs in Spain in terms of performing spirometry. The findings in the present study can be used to improve the performance of spirometry in these areas.

Differences in the use of spirometry between rural and urban primary care centers in Spain

PubMed Central

Márquez-Martín, Eduardo; Soriano, Joan B; Rubio, Myriam Calle; Lopez-Campos, Jose Luis

2015-01-01

Objectives The aim of this study is to evaluate the ability and practice of spirometry, training of technicians, and spirometry features in primary care centers in Spain, evaluating those located in a rural environment against those in urban areas. Methods An observational cross-sectional study was conducted in 2012 by a telephone survey in 970 primary health care centers in Spain. The centers were divided into rural or urban depending on the catchment population. The survey contacted technicians in charge of spirometry and consisted of 36 questions related to the test that included the following topics: center resources, training doctors and technicians, using the spirometer, bronchodilator test, and the availability of spirometry and maintenance. Results Although the sample size was achieved in both settings, rural centers (RCs) gave a lower response rate than urban centers (UCs). The number of centers without spirometry in rural areas doubled those in the urban areas. Most centers had between one and two spirometers. However, the number of spirometry tests per week was significantly lower in RCs than in UCs (4 [4.1%] vs 6.9 [5.7%], P<0.01). The availability of a specific schedule for conducting spirometries was higher in RCs than in UCs (209 [73.0%] vs 207 [64.2%], P=0.003). RCs were more satisfied with the spirometries (7.8 vs 7.6, P=0.019) and received more training course for interpreting spirometry (41.0% vs 33.2%, P=0.004). The performance of the bronchodilator test showed a homogeneous measure in different ways. The spirometer type and the reference values were unknown to the majority of respondents. Conclusion This study shows the differences between primary care RCs and UCs in Spain in terms of performing spirometry. The findings in the present study can be used to improve the performance of spirometry in these areas. PMID:26316737

Early Events in Retinal Degeneration Caused by Rhodopsin Mutation or Pigment Epithelium Malfunction: Differences and Similarities

PubMed Central

Di Pierdomenico, Johnny; García-Ayuso, Diego; Pinilla, Isabel; Cuenca, Nicolás; Vidal-Sanz, Manuel; Agudo-Barriuso, Marta; Villegas-Pérez, María P.

2017-01-01

To study the course of photoreceptor cell death and macro and microglial reactivity in two rat models of retinal degeneration with different etiologies. Retinas from P23H-1 (rhodopsin mutation) and Royal College of Surgeon (RCS, pigment epithelium malfunction) rats and age-matched control animals (Sprague-Dawley and Pievald Viro Glaxo, respectively) were cross-sectioned at different postnatal ages (from P10 to P60) and rhodopsin, L/M- and S-opsin, ionized calcium-binding adapter molecule 1 (Iba1), glial fibrillary acid protein (GFAP), and proliferating cell nuclear antigen (PCNA) proteins were immunodetected. Photoreceptor nuclei rows and microglial cells in the different retinal layers were quantified. Photoreceptor degeneration starts earlier and progresses quicker in P23H-1 than in RCS rats. In both models, microglial cell activation occurs simultaneously with the initiation of photoreceptor death while GFAP over-expression starts later. As degeneration progresses, the numbers of microglial cells increase in the retina, but decreasing in the inner retina and increasing in the outer retina, more markedly in RCS rats. Interestingly, and in contrast with healthy animals, microglial cells reach the outer nuclei and outer segment layers. The higher number of microglial cells in dystrophic retinas cannot be fully accounted by intraretinal migration and PCNA immunodetection revealed microglial proliferation in both models but more importantly in RCS rats. The etiology of retinal degeneration determines the initiation and pattern of photoreceptor cell death and simultaneously there is microglial activation and migration, while the macroglial response is delayed. The actions of microglial cells in the degeneration cannot be explained only in the basis of photoreceptor death because they participate more actively in the RCS model. Thus, the retinal degeneration caused by pigment epithelium malfunction is more inflammatory and would probably respond better to interventions by inhibiting microglial cells. PMID:28321183

Validation of the German version of two scales (RIS, RCS-HCP) for measuring regret associated with providing healthcare.

PubMed

Richner, Silvia C; Cullati, Stéphane; Cheval, Boris; Schmidt, Ralph E; Chopard, Pierre; Meier, Christoph A; Courvoisier, Delphine S

2017-03-24

The regret intensity scale (RIS) and the regret coping scale for healthcare professionals (RCS-HCP) working in hospitals assess the experience of care-related regrets and how healthcare professional deal with these negative events. The aim of this study was to validate a German version of the RIS and the RCS-HCP. The RIS and RCS-HCP in German were first translated into German (forward- and backward translations) and then pretested with 16 German-speaking healthcare professionals. Finally, two surveys (test and 1-month retest) administered the scales to a large sample of healthcare professionals from two different hospitals. Of the 2142 eligible healthcare professionals, 494 (23.1%) individuals (108 physicians) completed the cross-sectional web based survey and 244 completed the retest questionnaire. Participants (n = 165, 33.4% of the total sample) who reported not having experienced a regret in the last 5 years, had significantly more days of sick leave during the last 6 months. These participants were excluded from the subsequent analyses. The structure of the scales was similar to the French version with a single dimension for the regret intensity scale (Cronbach's alpha: 0.88) and three types of coping strategies for the regret coping scale (alphas: 0.69 for problem-focused strategies, 0.67 for adaptive strategies and 0.86 for the maladaptive strategies). Construct validity was good and reproduced the findings of the French study, namely that higher regret intensity was associated with situations that entailed more consequences for the patients. Furthermore, higher regret intensity and more frequent use of maladaptive strategies were associated with more sleep difficulties and less work satisfaction. The German RIS and RCS-HCP scales were found valid for measuring regret intensity and regret coping in a population of healthcare professionals working in a hospital. Reporting no regret, which corresponds to the coping strategy of suppression, seems to be a maladaptive strategy because it was associated with more frequent sick day leaves.

Inferior ectopic pupil and typical ocular coloboma in RCS rats.

PubMed

Tsuji, Naho; Ozaki, Kiyokazu; Narama, Isao; Matsuura, Tetsuro

2011-08-01

Ocular coloboma is sometimes accompanied by corectopia in humans and therefore ectopic pupil may indicate ocular coloboma in experimental animals. The RCS strain of rats has a low incidence of microphthalmia. We found that inferior ectopic pupil is associated exclusively with small-sized eyes in this strain. The objective of the current study was to evaluate whether inferior ectopic pupil is associated with iridal coloboma and other types of ocular coloboma in RCS rats. Both eyes of RCS rats were examined clinically, and those with inferior ectopic pupils underwent morphologic and morphometric examinations. In a prenatal study, coronal serial sections of eyeballs from fetuses at gestational day 16.5 were examined by using light microscopy. Ectopic pupils in RCS rats were found exclusively in an inferior position, where the iris was shortened. Fundic examination revealed severe chorioretinal coloboma in all cases of inferior ectopic pupil. The morphologic characteristics closely resembled those of chorioretinal coloboma in humans. Histopathologic examination of primordia showed incomplete closure of the optic fissure in 4 eyeballs of RCS fetuses. Neither F(1) rats nor N(2) (progeny of RCS × BN matings) displayed any ocular anomalies, including ectopic pupils. The RCS strain is a suitable model for human ocular coloboma, and inferior ectopic pupil appears to be a strong indicator of ocular coloboma.

Inferior Ectopic Pupil and Typical Ocular Coloboma in RCS Rats

PubMed Central

Tsuji, Naho; Ozaki, Kiyokazu; Narama, Isao; Matsuura, Tetsuro

2011-01-01

Ocular coloboma is sometimes accompanied by corectopia in humans and therefore ectopic pupil may indicate ocular coloboma in experimental animals. The RCS strain of rats has a low incidence of microphthalmia. We found that inferior ectopic pupil is associated exclusively with small-sized eyes in this strain. The objective of the current study was to evaluate whether inferior ectopic pupil is associated with iridal coloboma and other types of ocular coloboma in RCS rats. Both eyes of RCS rats were examined clinically, and those with inferior ectopic pupils underwent morphologic and morphometric examinations. In a prenatal study, coronal serial sections of eyeballs from fetuses at gestational day 16.5 were examined by using light microscopy. Ectopic pupils in RCS rats were found exclusively in an inferior position, where the iris was shortened. Fundic examination revealed severe chorioretinal coloboma in all cases of inferior ectopic pupil. The morphologic characteristics closely resembled those of chorioretinal coloboma in humans. Histopathologic examination of primordia showed incomplete closure of the optic fissure in 4 eyeballs of RCS fetuses. Neither F1 rats nor N2 (progeny of RCS × BN matings) displayed any ocular anomalies, including ectopic pupils. The RCS strain is a suitable model for human ocular coloboma, and inferior ectopic pupil appears to be a strong indicator of ocular coloboma. PMID:22330254

Medical radar considerations for detecting and monitoring Crohn's disease

NASA Astrophysics Data System (ADS)

Smith, Sonny; Narayanan, Ram M.; Messaris, Evangelos

2014-05-01

Crohn's disease is a condition that causes inflammation and associated complications along any section of the digestive tract. Over the years, numerous radiological and endoscopic methods as well as the use of ultrasound have been developed to examine and diagnose inflammatory bowel disorders such as Crohn's disease. While such techniques have much merit, an alternative medical solution that is safe, non-invasive, and inexpensive is proposed in this paper. Reflections from electromagnetic signals transmitted by an ultra-wide band (UWB) radar allow for not only range (or extent) information but also spectral analysis of a given target of interest. Moreover, the radar cross-section (RCS) of an object measures how detectable the electromagnetic return energy of such an object is to the radar. In the preliminary phase of research, we investigate how disparities in the dielectric properties of diseased versus non-diseased portions of the intestines can aid in the detection of Crohn's disease. RCS analysis from finite-difference time-domain (FDTD) method simulations using a simple 3D model of the intestines are presented. The ultimate goal of our research is to design a UWB radar system using a suitable waveform to detect and monitor Crohn's disease.

Specification for a surface-search radar-detection-range model

NASA Astrophysics Data System (ADS)

Hattan, Claude P.

1990-09-01

A model that predicts surface-search radar detection range versus a variety of combatants has been developed at the Naval Ocean Systems Center. This model uses a simplified ship radar cross section (RCS) model and the U.S. Navy Oceanographic and Atmospheric Mission Library Standard Electromagnetic Propagation Model. It provides the user with a method of assessing the effects of the environment of the performance of a surface-search radar system. The software implementation of the model is written in ANSI FORTRAN 77, with MIL-STD-1753 extensions. The program provides the user with a table of expected detection ranges when the model is supplied with the proper environmental radar system inputs. The target model includes the variation in RCS as a function of aspect angle and the distribution of reflected radar energy as a function of height above the waterline. The modeled propagation effects include refraction caused by a multisegmented refractivity profile, sea-surface roughness caused by local winds, evaporation ducting, and surface-based ducts caused by atmospheric layering.

Multilevel fast multipole method based on a potential formulation for 3D electromagnetic scattering problems.

PubMed

Fall, Mandiaye; Boutami, Salim; Glière, Alain; Stout, Brian; Hazart, Jerome

2013-06-01

A combination of the multilevel fast multipole method (MLFMM) and boundary element method (BEM) can solve large scale photonics problems of arbitrary geometry. Here, MLFMM-BEM algorithm based on a scalar and vector potential formulation, instead of the more conventional electric and magnetic field formulations, is described. The method can deal with multiple lossy or lossless dielectric objects of arbitrary geometry, be they nested, in contact, or dispersed. Several examples are used to demonstrate that this method is able to efficiently handle 3D photonic scatterers involving large numbers of unknowns. Absorption, scattering, and extinction efficiencies of gold nanoparticle spheres, calculated by the MLFMM, are compared with Mie's theory. MLFMM calculations of the bistatic radar cross section (RCS) of a gold sphere near the plasmon resonance and of a silica coated gold sphere are also compared with Mie theory predictions. Finally, the bistatic RCS of a nanoparticle gold-silver heterodimer calculated with MLFMM is compared with unmodified BEM calculations.

Experimental Demonstration of Printed Graphene Nano-flakes Enabled Flexible and Conformable Wideband Radar Absorbers.

PubMed

Huang, Xianjun; Pan, Kewen; Hu, Zhirun

2016-12-07

In this work, we have designed, fabricated and experimentally characterized a printed graphene nano-flakes enabled flexible and conformable wideband radar absorber. The absorber covers both X (8-12 GHz) and Ku (12-18 GHz) bands and is printed on flexible substrate using graphene nano-flakes conductive ink through stencil printing method. The measured results show that an effective absorption (above 90%) bandwidth spans from 10.4 GHz to 19.7 GHz, namely a 62% fraction bandwidth, with only 2 mm thickness. The flexibility of the printed graphene nano-flakes enables the absorber conformably bending and attaching to a metal cylinder. The radar cross section (RCS) of the cylinder with and without absorber attachment has been compared and excellent absorption has been obtained. Only 3.6% bandwidth reduction has been observed comparing to that of un-bended absorber. This work has demonstrated unambiguously that printed graphene can provide flexible and conformable wideband radar absorption, which extends the graphene's application to practical RCS reductions.

Efficient propagation-inside-layer expansion algorithm for solving the scattering from three-dimensional nested homogeneous dielectric bodies with arbitrary shape.

PubMed

Bellez, Sami; Bourlier, Christophe; Kubické, Gildas

2015-03-01

This paper deals with the evaluation of electromagnetic scattering from a three-dimensional structure consisting of two nested homogeneous dielectric bodies with arbitrary shape. The scattering problem is formulated in terms of a set of Poggio-Miller-Chang-Harrington-Wu integral equations that are afterwards converted into a system of linear equations (impedance matrix equation) by applying the Galerkin method of moments (MoM) with Rao-Wilton-Glisson basis functions. The MoM matrix equation is then solved by deploying the iterative propagation-inside-layer expansion (PILE) method in order to obtain the unknown surface current densities, which are thereafter used to handle the radar cross-section (RCS) patterns. Some numerical results for various structures including canonical geometries are presented and compared with those of the FEKO software in order to validate the PILE-based approach as well as to show its efficiency to analyze the full-polarized RCS patterns.

Radar waveform requirements for reliable detection of an aircraft-launched missile

NASA Astrophysics Data System (ADS)

Blair, W. Dale; Brandt-Pearce, Maite

1996-06-01

When tracking a manned aircraft with a phase array radar, detecting a missile launch (i.e., a target split) is particularly important because the missile can have a very small radar cross section (RCS) and drop below the horizon of the radar shortly after launch. Reliable detection of the launch is made difficult because the RCS of the missile is very small compared to that of the manned aircraft and the radar typically revisits a manned aircraft every few seconds. Furthermore, any measurements of the aircraft and missile taken shortly after the launch will be merged until the two targets are resolved in range, frequency, or space. In this paper, detection of the launched missile is addressed through the detection of the presence of target multiplicity with the in-phase and quadrature monopulse measurements. The probability of detecting the launch using monopulse processing will be studied with regard to the tracking signal-to-noise ratio and the number of pulses n the radar waveform.

Analysis of cylindrical wrap-around and doubly conformal patch antennas by way of the finite element-artificial absorber method

NASA Technical Reports Server (NTRS)

Volakis, J. L.; Kempel, L. C.; Sliva, R.; Wang, H. T. G.; Woo, A. G.

1994-01-01

The goal of this project was to develop analysis codes for computing the scattering and radiation of antennas on cylindrically and doubly conformal platforms. The finite element-boundary integral (FE-BI) method has been shown to accurately model the scattering and radiation of cavity-backed patch antennas. Unfortunately extension of this rigorous technique to coated or doubly curved platforms is cumbersome and inefficient. An alternative approximate approach is to employ an absorbing boundary condition (ABC) for terminating the finite element mesh thus avoiding use of a Green's function. A FE-ABC method is used to calculate the radar cross section (RCS) and radiation pattern of a cavity-backed patch antenna which is recessed within a metallic surface. It is shown that this approach is accurate for RCS and antenna pattern calculations with an ABC surface displaced as little as 0.3 lambda from the cavity aperture. These patch antennas may have a dielectric overlay which may also be modeled with this technique.

76 FR 73727 - Biweekly Notice; Applications and Amendments to Facility Operating Licenses Involving No...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-29

... Detection Instrumentation,'' to define a new time limit for restoring inoperable RCS leakage detection... Specifications Section 3.4.15 regarding reactor coolant leakage detection instrumentation to be consistent with... amendments revised the Technical Specifications (TSs) ``RCS [reactor coolant system] Leakage Detection...

Comparison of two target classification techniques

NASA Astrophysics Data System (ADS)

Chen, J. S.; Walton, E. K.

1986-01-01

Radar target classification techniques based on backscatter measurements in the resonance region (1.0-20.0 MHz) are discussed. Attention is given to two novel methods currently being tested at the radar range of Ohio State University. The methods include: (1) the nearest neighbor (NN) algorithm for determining the radar cross section (RCS) magnitude and range corrected phase at various operating frequencies; and (2) an inverse Fourier transformation of the complex multifrequency radar returns of the time domain, followed by cross correlation analysis. Comparisons are made of the performance of the two techniques as a function of signal-to-error noise ratio for different types of processing. The results of the comparison are discussed in detail.

High-frequency techniques for RCS prediction of plate geometries and a physical optics/equivalent currents model for the RCS of trihedral corner reflectors, parts 1 and 2

NASA Technical Reports Server (NTRS)

Balanis, Constantine A.; Polka, Lesley A.; Polycarpou, Anastasis C.

1994-01-01

Formulations for scattering from the coated plate and the coated dihedral corner reflector are included. A coated plate model based upon the Uniform Theory of Diffraction (UTD) for impedance wedges was presented in the last report. In order to resolve inaccuracies and discontinuities in the predicted patterns using the UTD-based model, an improved model that uses more accurate diffraction coefficients is presented. A Physical Optics (PO) model for the coated dihedral corner reflector is presented as an intermediary step in developing a high-frequency model for this structure. The PO model is based upon the reflection coefficients for a metal-backed lossy material. Preliminary PO results for the dihedral corner reflector suggest that, in addition to being much faster computationally, this model may be more accurate than existing moment method (MM) models. An improved Physical Optics (PO)/Equivalent Currents model for modeling the Radar Cross Section (RCS) of both square and triangular, perfectly conducting, trihedral corner reflectors is presented. The new model uses the PO approximation at each reflection for the first- and second-order reflection terms. For the third-order reflection terms, a Geometrical Optics (GO) approximation is used for the first reflection; and PO approximations are used for the remaining reflections. The previously reported model used GO for all reflections except the terminating reflection. Using PO for most of the reflections results in a computationally slower model because many integrations must be performed numerically, but the advantage is that the predicted RCS using the new model is much more accurate. Comparisons between the two PO models, Finite-Difference Time-Domain (FDTD) and experimental data are presented for validation of the new model.

Finite difference time domain modeling of spiral antennas

NASA Technical Reports Server (NTRS)

Penney, Christopher W.; Beggs, John H.; Luebbers, Raymond J.

1992-01-01

The objectives outlined in the original proposal for this project were to create a well-documented computer analysis model based on the finite-difference, time-domain (FDTD) method that would be capable of computing antenna impedance, far-zone radiation patterns, and radar cross-section (RCS). The ability to model a variety of penetrable materials in addition to conductors is also desired. The spiral antennas under study by this project meet these requirements since they are constructed of slots cut into conducting surfaces which are backed by dielectric materials.

Wideband-Switchable Metamaterial Absorber Using Injected Liquid Metal.

PubMed

Kim, Hyung Ki; Lee, Dongju; Lim, Sungjoon

2016-08-22

Metamaterial absorbers can provide good solutions for radar-cross-section (RCS) reduction. In spite of their attractive features of thinness, lightness, and low cost, resonant metamaterial absorbers have a drawback of narrow bandwidth. For practical radar applications, wideband absorbers are necessary. In this paper, we propose a wideband-switchable metamaterial absorber using liquid metal. In order to reduce RCS both for X-band and C-band, the switchable Jerusalem cross (JC) resonator is introduced. The JC resonator consists of slotted circular rings, chip resistors, and microfluidic channels. The JC resonator is etched on a flexible printed circuit board (FPCB), and the microfluidic channels are laser-etched on a polydimethylsiloxane (PDMS) material. The proposed absorber can switch the absorption frequency band by injecting a liquid metal alloy into the channels. The performance of the absorber was demonstrated through full-wave simulation and through measurements employing prototypes. The experimental results showed absorption ratios of over 90% from 7.43 GHz to 14.34 GHz, and from 5.62 GHz to 7.3 GHz, with empty channels and liquid metal-filled channels, respectively. Therefore, the absorption band was successfully switched between the C-band (4-8 GHz) and the X-band (8-12 GHz) by injecting liquid metal eutectic gallium indium alloy (EGaIn) into the channels.

Wideband-Switchable Metamaterial Absorber Using Injected Liquid Metal

NASA Astrophysics Data System (ADS)

Kim, Hyung Ki; Lee, Dongju; Lim, Sungjoon

2016-08-01

Metamaterial absorbers can provide good solutions for radar-cross-section (RCS) reduction. In spite of their attractive features of thinness, lightness, and low cost, resonant metamaterial absorbers have a drawback of narrow bandwidth. For practical radar applications, wideband absorbers are necessary. In this paper, we propose a wideband-switchable metamaterial absorber using liquid metal. In order to reduce RCS both for X-band and C-band, the switchable Jerusalem cross (JC) resonator is introduced. The JC resonator consists of slotted circular rings, chip resistors, and microfluidic channels. The JC resonator is etched on a flexible printed circuit board (FPCB), and the microfluidic channels are laser-etched on a polydimethylsiloxane (PDMS) material. The proposed absorber can switch the absorption frequency band by injecting a liquid metal alloy into the channels. The performance of the absorber was demonstrated through full-wave simulation and through measurements employing prototypes. The experimental results showed absorption ratios of over 90% from 7.43 GHz to 14.34 GHz, and from 5.62 GHz to 7.3 GHz, with empty channels and liquid metal-filled channels, respectively. Therefore, the absorption band was successfully switched between the C-band (4-8 GHz) and the X-band (8-12 GHz) by injecting liquid metal eutectic gallium indium alloy (EGaIn) into the channels.

Formation of Dense Plasma around a Small Meteoroid: Kinetic Theory and its Implications

NASA Astrophysics Data System (ADS)

Dimant, Y. S.; Oppenheim, M. M.; Marshall, R.

2016-12-01

Every second, millions of small meteoroids hit the Earth from space, the vast majority too small to observe visually. Radars easily detect the plasma generated during meteoroid ablation and use this data to characterize the meteoroids and the atmosphere in which they disintegrate. Reflections of radar pulses from this plasma produce a signal called a head echo. We have developed a first-principle kinetic theory to describe the behavior of meteoric particles ablated from a fast-moving meteoroid and partially ionized through collisions with the atmosphere. This theory produces analytic expressions describing the ion and neutral density and velocity distributions. This analytical model will allow more accurate quantitative interpretations of head echo radar measurements. These, in turn, will improve our ability to infer meteoroid and atmospheric properties. Figure shows the theoretically predicted spatial distribution of the near-meteoroid plasma. This distribution is axially symmetric with respect to the path of the meteoroid. The plasma density within a collisional mean-free-path length drops in proportion to 1/R where R is the distance from the meteoroid center. Beyond this distance and behind the meteoroid, the density transitions to ∝ 1/R². This behavior makes the near-meteoroid plasma overdense to the propagating radar wave in all cases at locations sufficiently close to the meteoroid. Using the FDTD model of Marshall and Close [2015], we use this plasma density distribution to calculate the radar cross section (RCS) from head echoes. Consistent with the results of Marshall and Close [2015], we find that the RCS is given by the cross-section area of the meteor plasma inside which the plasma is overdense - the "overdense area" - as viewed from the radar. Since the distribution derived here is specified by two parameters, this result suggests that the meteor plasma distribution can be specified with two measurements of RCS at different frequencies, as was done by Close et al [2004]. The specification of the meteor plasma distribution then leads to an improved estimate of the parent meteoroid mass, a critical parameter for understanding the global meteoroid flux and deposition in the atmosphere. Work is supported by NSF Grant AGS-1244842.

User's manual for three dimensional FDTD version C code for scattering from frequency-independent dielectric and magnetic materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Version C is a three dimensional numerical electromagnetic scattering code based upon the Finite Difference Time Domain Technique (FDTD). The supplied version of the code is one version of our current three dimensional FDTD code set. This manual provides a description of the code and corresponding results for several scattering problems. The manual is organized into fourteen sections: introduction, description of the FDTD method, operation, resource requirements, Version C code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMONC.FOR), a section briefly discussing Radar Cross Section (RCS) computations, a section discussing some scattering results, a sample problem setup section, a new problem checklist, references and figure titles.

User's manual for three dimensional FDTD version D code for scattering from frequency-dependent dielectric and magnetic materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Version D is a three dimensional numerical electromagnetic scattering code based upon the Finite Difference Time Domain Technique (FDTD). The supplied version of the code is one version of our current three dimensional FDTD code set. This manual provides a description of the code and corresponding results for several scattering problems. The manual is organized into fourteen sections: introduction, description of the FDTD method, operation, resource requirements, Version D code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMOND.FOR), a section briefly discussing Radar Cross Section (RCS) computations, a section discussing some scattering results, a sample problem setup section, a new problem checklist, references and figure titles.

User's manual for three dimensional FDTD version A code for scattering from frequency-independent dielectric materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1992-01-01

The Penn State Finite Difference Time Domain (FDTD) Electromagnetic Scattering Code Version A is a three dimensional numerical electromagnetic scattering code based on the Finite Difference Time Domain technique. The supplied version of the code is one version of our current three dimensional FDTD code set. The manual provides a description of the code and the corresponding results for the default scattering problem. The manual is organized into 14 sections: introduction, description of the FDTD method, operation, resource requirements, Version A code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMONA.FOR), a section briefly discussing radar cross section (RCS) computations, a section discussing the scattering results, a sample problem setup section, a new problem checklist, references, and figure titles.

User's manual for three dimensional FDTD version B code for scattering from frequency-dependent dielectric materials

NASA Technical Reports Server (NTRS)

Beggs, John H.; Luebbers, Raymond J.; Kunz, Karl S.

1991-01-01

The Penn State Finite Difference Time Domain Electromagnetic Scattering Code Version B is a three dimensional numerical electromagnetic scattering code based upon the Finite Difference Time Domain Technique (FDTD). The supplied version of the code is one version of our current three dimensional FDTD code set. This manual provides a description of the code and corresponding results for several scattering problems. The manual is organized into fourteen sections: introduction, description of the FDTD method, operation, resource requirements, Version B code capabilities, a brief description of the default scattering geometry, a brief description of each subroutine, a description of the include file (COMMONB.FOR), a section briefly discussing Radar Cross Section (RCS) computations, a section discussing some scattering results, a sample problem setup section, a new problem checklist, references and figure titles.

Simultaneous optical and meteor head echo measurements using the Middle Atmosphere Alomar Radar System (MAARSY): Data collection and preliminary analysis

NASA Astrophysics Data System (ADS)

Brown, P.; Stober, G.; Schult, C.; Krzeminski, Z.; Cooke, W.; Chau, J. L.

2017-07-01

The initial results of a two year simultaneous optical-radar meteor campaign are described. Analysis of 105 double-station optical meteors having plane of sky intersection angles greater than 5° and trail lengths in excess of 2 km also detected by the Middle Atmosphere Alomar Radar System (MAARSY) as head echoes was performed. These events show a median deviation in radiants between radar and optical determinations of 1.5°, with 1/3 of events having radiant agreement to less than one degree. MAARSY tends to record average speeds roughly 0.5 km/s and 1.3 km higher than optical records, in part due to the higher sensitivity of MAARSY as compared to the optical instruments. More than 98% of all head echoes are not detected with the optical system. Using this non-detection ratio and the known limiting sensitivity of the cameras, we estimate that the limiting meteoroid detection mass of MAARSY is in the 10-9-10-10 kg (astronomical limiting meteor magnitudes of +11 to +12) appropriate to speeds from 30 to 60 km/s. There is a clear trend of higher peak RCS for brighter meteors between 35 and -30 dBsm. For meteors with similar magnitudes, the MAARSY head echo radar cross-section is larger at higher speeds. Brighter meteors at fixed heights and similar speeds have consistently, on average, larger RCS values, in accordance with established scattering theory. However, our data show RCS ∝ v/2, much weaker than the normally assumed RCS ∝ v3, a consequence of our requiring head echoes to also be detectable optically. Most events show a smooth variation of RCS with height broadly following the light production behavior. A significant minority of meteors show large variations in RCS relative to the optical light curve over common height intervals, reflecting fragmentation or possibly differential ablation. No optically detected meteor occurring in the main radar beam and at times when the radar was collecting head echo data went unrecorded by MAARSY. Thus there does not appear to be any large scale bias in MAARSY head echo detections for the (comparatively) larger optical events in our dataset, even at very low speeds.

Photopic ERG negative response from amacrine cell signaling in RCS rat retinal degeneration.

PubMed

Machida, Shigeki; Raz-Prag, Dorit; Fariss, Robert N; Sieving, Paul A; Bush, Ronald A

2008-01-01

The authors investigated photopic electroretinographic changes during degeneration in the Royal College of Surgeons (RCS) and transgenic P23H rhodopsin rat models, including the cellular origins of a large corneal-negative component that persists in the RCS rat. Photopic and scotopic electroretinograms (ERGs) were recorded from dystrophic RCS (RCS-p(+)/Lav) rats (4-18 weeks old) and transgenic rhodopsin Pro23His line 1 (P23H) rats (4-30 weeks old). Age-matched congenic (RCS-rdy(+)p(+)/Lav) and Sprague-Dawley rats were used as controls. N-methyl-DL-aspartic acid (NMA), dopamine, and gamma-aminobutyric acid (GABA) were injected intravitreally, and optic nerve sectioning (ONS) was performed to suppress or remove inner retinal neuron activity. Retinal morphology for cone cell counts and immunohistochemistry for quantification of Kir4.1 channels were performed at various stages of degeneration. As degeneration progressed, the photopic ERG of RCS dystrophic rats was distinctly different from that of P23H rats, primarily because of the growth of a corneal-negative response (RCS-NPR) after the b-wave in RCS rats. This response had a peak time similar to the photopic negative response (PhNR) in controls but with a more gradual recovery phase, and it was not affected by ONS. The PhNR in P23H rats declined linearly with the b-wave. NMA and GABA eliminated the RCS-NPR and uncovered a larger b-wave in RCS rats at late stages of degeneration, but NMA had little effect on the ERG in P23H rats. The NMA-sensitive negative response in RCS rats declined with age more slowly than did the NMA-isolated b-wave. The density of Kir4.1 channels at the endfeet of Müller cells and in the proximal retina increased significantly between 6 to 10 weeks and 14 weeks of age in the RCS rat retina but not in the P23H rat retina. The photopic ERG of the dystrophic RCS rat retina becomes increasingly electronegative because of an aberrant negative response, originating from amacrine cell activity, which declines more slowly than the b-wave with degeneration. The absence of this response in the P23H rat indicates that the inner retinal cone pathway pathology is different in the two models. A relative increase in Kir4.1 channels on Müller cells of RCS retina may contribute to the enhanced negative ERG response in the RCS rat.

Space shuttle orbiter rear mounted reaction control system jet interaction study. [hypersonic wind tunnel tests

NASA Technical Reports Server (NTRS)

Rausch, J. R.

1977-01-01

The effect of interaction between the reaction control system (RCS) jets and the flow over the space shuttle orbiter in the atmosphere was investigated in the NASA Langley 31-inch continuous flow hypersonic tunnel at a nominal Mach number of 10.3 and in the AEDC continuous flow hypersonic tunnel B at a nominal Mach number of 6, using 0.01 and .0125 scale force models with aft RCS nozzles mounted both on the model and on the sting of the force model balance. The data show that RCS nozzle exit momentum ratio is the primary correlating parameter for effects where the plume impinges on an adjacent surface and mass flow ratio is the parameter when the plume interaction is primarily with the external stream. An analytic model of aft mounted RCS units was developed in which the total reaction control moments are the sum of thrust, impingement, interaction, and cross-coupling terms.

Long-term Characterization of Retinal Degeneration in Royal College of Surgeons Rats Using Spectral-Domain Optical Coherence Tomography

PubMed Central

Ryals, Renee C.; Andrews, Michael D.; Datta, Shreya; Coyner, Aaron S.; Fischer, Cody M.; Wen, Yuquan; Pennesi, Mark E.; McGill, Trevor J.

2017-01-01

Purpose Prospective treatments for age-related macular degeneration and inherited retinal degenerations are commonly evaluated in the Royal College of Surgeons (RCS) rat before translation into clinical application. Historically, retinal thickness obtained through postmortem anatomic assessments has been a key outcome measure; however, utility of this measurement is limited because it precludes the ability to perform longitudinal studies. To overcome this limitation, the present study was designed to provide a baseline longitudinal quantification of retinal thickness in the RCS rat by using spectral-domain optical coherence tomography (SD-OCT). Methods Horizontal and vertical linear SD-OCT scans centered on the optic nerve were captured from Long-Evans control rats at P30, P60, P90 and from RCS rats between P17 and P90. Total retina (TR), outer nuclear layer+ (ONL+), inner nuclear layer (INL), and retinal pigment epithelium (RPE) thicknesses were quantified. Histologic sections of RCS retina obtained from P21 to P60 were compared to SD-OCT images. Results In RCS rats, TR and ONL+ thickness decreased significantly as compared to Long-Evans controls. Changes in INL and RPE thickness were not significantly different between control and RCS retinas. From P30 to P90 a subretinal hyperreflective layer (HRL) was observed and quantified in RCS rats. After correlation with histology, the HRL was identified as disorganized outer segments and the location of accumulated debris. Conclusions Retinal layer thickness can be quantified longitudinally throughout the course of retinal degeneration in the RCS rat by using SD-OCT. Thickness measurements obtained with SD-OCT were consistent with previous anatomic thickness assessments. This study provides baseline data for future longitudinal assessment of therapeutic agents in the RCS rat. PMID:28253400

Long-term Characterization of Retinal Degeneration in Royal College of Surgeons Rats Using Spectral-Domain Optical Coherence Tomography.

PubMed

Ryals, Renee C; Andrews, Michael D; Datta, Shreya; Coyner, Aaron S; Fischer, Cody M; Wen, Yuquan; Pennesi, Mark E; McGill, Trevor J

2017-03-01

Prospective treatments for age-related macular degeneration and inherited retinal degenerations are commonly evaluated in the Royal College of Surgeons (RCS) rat before translation into clinical application. Historically, retinal thickness obtained through postmortem anatomic assessments has been a key outcome measure; however, utility of this measurement is limited because it precludes the ability to perform longitudinal studies. To overcome this limitation, the present study was designed to provide a baseline longitudinal quantification of retinal thickness in the RCS rat by using spectral-domain optical coherence tomography (SD-OCT). Horizontal and vertical linear SD-OCT scans centered on the optic nerve were captured from Long-Evans control rats at P30, P60, P90 and from RCS rats between P17 and P90. Total retina (TR), outer nuclear layer+ (ONL+), inner nuclear layer (INL), and retinal pigment epithelium (RPE) thicknesses were quantified. Histologic sections of RCS retina obtained from P21 to P60 were compared to SD-OCT images. In RCS rats, TR and ONL+ thickness decreased significantly as compared to Long-Evans controls. Changes in INL and RPE thickness were not significantly different between control and RCS retinas. From P30 to P90 a subretinal hyperreflective layer (HRL) was observed and quantified in RCS rats. After correlation with histology, the HRL was identified as disorganized outer segments and the location of accumulated debris. Retinal layer thickness can be quantified longitudinally throughout the course of retinal degeneration in the RCS rat by using SD-OCT. Thickness measurements obtained with SD-OCT were consistent with previous anatomic thickness assessments. This study provides baseline data for future longitudinal assessment of therapeutic agents in the RCS rat.

[The modification of electrophysiology affected by ectopic synapse in ON-retinal bipolar cells of RCS rats].

PubMed

Zhang, Chen-xing; Yin, Zheng-qin; Weng, Chuan-huang; Zeng, Yu-xiao

2011-03-01

To study the influence of the ectopic synapse for electrophysiological characteristics modification in ON retinal bipolar cells (ON-RBCs) of RCS rat. Immunofluorescence of the retinal frozen section was taken in P60 d, P90 d of RCS rat (RCS) and control rat (CTR) with the anti-mGluR6 and anti-Synaptophysin, Lucifer Yellow staining solo ON-RBCs was taken in all the group. The whole cell recording was performed in the retinal slice of P60 d, P90 d in RCS and CTR. The modification of the passive membrane properties and the outward currents properties in RCS-ON-RBCs, CTR-ON-RBCs and CTR-OFF-RBCs were observed. RCS-ON-RBCs stretched out the ectopic neurite in different direction and the activity of synapse could be detected around the ectopic neurite. From Pn60d, passive membrane properties of RCS-ON-RBCs kept immature, The RMP in RCS-ON-RBCs and CTR-ON-RBCs were (-61.8 ± 3.07), (-50.44 ± 1.36) mV and (-63.1 ± 2.59), (-48.37 ± 3.69) mV when P60 d and P90 d, there ware significantly higher than CTR group (t = 2.191, 2.435, 5.817, 6.912;P < 0.05). The IR in RCS-ON-RBCs and CTR-ON-RBCs were (323.3 ± 42.6), (337.6 ± 71.3) MΩ and (321.2 ± 58.6), (340.3 ± 62.8) MΩ when P60 d and P90 d, there ware significantly higher than CTR group (t = 3.561, 1.987, 5.211, 4.034; P < 0.05). Outward currents were recorded when giving hyper- and depolarized voltage steps. In retinal degeneration, the amplitude of outward currents in RCS-ON-RBCs is significantly different with CTR-ON-RBCs (t = 5.561, 6.341; P < 0.05) or CTR-OFF-RBCs (t = 5.357, 6.997; P < 0.05). The ectopic neurite from RCS-ON-RBCs has the possibility for translating the signal. In retinitis pigmentosa, the modification of electrophysiology characteristics in RCS-ON-RBCs was significantly different with CTR-ON-RBCs and CTR-OFF-RBCs. Influence with the ectopic neurite is the possible cause.

Ku-Band rendezvous radar performance computer simulation model

NASA Technical Reports Server (NTRS)

Magnusson, H. G.; Goff, M. F.

1984-01-01

All work performed on the Ku-band rendezvous radar performance computer simulation model program since the release of the preliminary final report is summarized. Developments on the program fall into three distinct categories: (1) modifications to the existing Ku-band radar tracking performance computer model; (2) the addition of a highly accurate, nonrealtime search and acquisition performance computer model to the total software package developed on this program; and (3) development of radar cross section (RCS) computation models for three additional satellites. All changes in the tracking model involved improvements in the automatic gain control (AGC) and the radar signal strength (RSS) computer models. Although the search and acquisition computer models were developed under the auspices of the Hughes Aircraft Company Ku-Band Integrated Radar and Communications Subsystem program office, they have been supplied to NASA as part of the Ku-band radar performance comuter model package. Their purpose is to predict Ku-band acquisition performance for specific satellite targets on specific missions. The RCS models were developed for three satellites: the Long Duration Exposure Facility (LDEF) spacecraft, the Solar Maximum Mission (SMM) spacecraft, and the Space Telescopes.

Experimental Demonstration of Printed Graphene Nano-flakes Enabled Flexible and Conformable Wideband Radar Absorbers

PubMed Central

Huang, Xianjun; Pan, Kewen; Hu, Zhirun

2016-01-01

In this work, we have designed, fabricated and experimentally characterized a printed graphene nano-flakes enabled flexible and conformable wideband radar absorber. The absorber covers both X (8–12 GHz) and Ku (12–18 GHz) bands and is printed on flexible substrate using graphene nano-flakes conductive ink through stencil printing method. The measured results show that an effective absorption (above 90%) bandwidth spans from 10.4 GHz to 19.7 GHz, namely a 62% fraction bandwidth, with only 2 mm thickness. The flexibility of the printed graphene nano-flakes enables the absorber conformably bending and attaching to a metal cylinder. The radar cross section (RCS) of the cylinder with and without absorber attachment has been compared and excellent absorption has been obtained. Only 3.6% bandwidth reduction has been observed comparing to that of un-bended absorber. This work has demonstrated unambiguously that printed graphene can provide flexible and conformable wideband radar absorption, which extends the graphene’s application to practical RCS reductions. PMID:27924823

Ku-Band rendezvous radar performance computer simulation model

NASA Astrophysics Data System (ADS)

Magnusson, H. G.; Goff, M. F.

1984-06-01

All work performed on the Ku-band rendezvous radar performance computer simulation model program since the release of the preliminary final report is summarized. Developments on the program fall into three distinct categories: (1) modifications to the existing Ku-band radar tracking performance computer model; (2) the addition of a highly accurate, nonrealtime search and acquisition performance computer model to the total software package developed on this program; and (3) development of radar cross section (RCS) computation models for three additional satellites. All changes in the tracking model involved improvements in the automatic gain control (AGC) and the radar signal strength (RSS) computer models. Although the search and acquisition computer models were developed under the auspices of the Hughes Aircraft Company Ku-Band Integrated Radar and Communications Subsystem program office, they have been supplied to NASA as part of the Ku-band radar performance comuter model package. Their purpose is to predict Ku-band acquisition performance for specific satellite targets on specific missions. The RCS models were developed for three satellites: the Long Duration Exposure Facility (LDEF) spacecraft, the Solar Maximum Mission (SMM) spacecraft, and the Space Telescopes.

Target recognition based on the moment functions of radar signatures

NASA Astrophysics Data System (ADS)

Kim, Kyung-Tae; Kim, Hyo-Tae

2002-03-01

In this paper, we present the results of target recognition research based on the moment functions of various radar signatures, such as time-frequency signatures, range profiles, and scattering centers. The proposed approach utilizes geometrical moments or central moments of the obtained radar signatures. In particular, we derived exact and closed form expressions of the geometrical moments of the adaptive Gaussian representation (AGR), which is one of the adaptive joint time-frequency techniques, and also computed the central moments of range profiles and one-dimensional (1-D) scattering centers on a target, which are obtained by various super-resolution techniques. The obtained moment functions are further processed to provide small dimensional and redundancy-free feature vectors, and classified via a neural network approach or a Bayes classifier. The performances of the proposed technique are demonstrated using a simulated radar cross section (RCS) data set, or a measured RCS data set of various scaled aircraft models, obtained at the Pohang University of Science and Technology (POSTECH) compact range facility. Results show that the techniques in this paper can not only provide reliable classification accuracy, but also save computational resources.

Performance of resonant radar target identification algorithms using intra-class weighting functions

NASA Astrophysics Data System (ADS)

Mustafa, A.

The use of calibrated resonant-region radar cross section (RCS) measurements of targets for the classification of large aircraft is discussed. Errors in the RCS estimate of full scale aircraft flying over an ocean, introduced by the ionospheric variability and the sea conditions were studied. The Weighted Target Representative (WTR) classification algorithm was developed, implemented, tested and compared with the nearest neighbor (NN) algorithm. The WTR-algorithm has a low sensitivity to the uncertainty in the aspect angle of the unknown target returns. In addition, this algorithm was based on the development of a new catalog of representative data which reduces the storage requirements and increases the computational efficiency of the classification system compared to the NN-algorithm. Experiments were designed to study and evaluate the characteristics of the WTR- and the NN-algorithms, investigate the classifiability of targets and study the relative behavior of the number of misclassifications as a function of the target backscatter features. The classification results and statistics were shown in the form of performance curves, performance tables and confusion tables.

Spherical cloaking using nonlinear transformations for improved segmentation into concentric isotropic coatings.

PubMed

Qiu, Cheng-Wei; Hu, Li; Zhang, Baile; Wu, Bae-Ian; Johnson, Steven G; Joannopoulos, John D

2009-08-03

Two novel classes of spherical invisibility cloaks based on nonlinear transformation have been studied. The cloaking characteristics are presented by segmenting the nonlinear transformation based spherical cloak into concentric isotropic homogeneous coatings. Detailed investigations of the optimal discretization (e.g., thickness control of each layer, nonlinear factor, etc.) are presented for both linear and nonlinear spherical cloaks and their effects on invisibility performance are also discussed. The cloaking properties and our choice of optimal segmentation are verified by the numerical simulation of not only near-field electric-field distribution but also the far-field radar cross section (RCS).

Optimal illusion and invisibility of multilayered anisotropic cylinders and spheres.

PubMed

Zhang, Lin; Shi, Yan; Liang, Chang-Hong

2016-10-03

In this paper, full-wave electromagnetic scattering theory is employed to investigate illusion and invisibility of inhomogeneous anisotropic cylinders and spheres. With the use of a shell designed according to Mie series theory for multiple piecewise anisotropic layers, radar cross section (RCS) of the coated inhomogeneous anisotropic object can be dramatically reduced or disguised as another object in the long-wavelength limit. With the suitable adjustment of the anisotropy parameters of the shell, optimal illusion and invisibility characteristics of the coated inhomogeneous anisotropic object can be achieved. Details of theoretical analysis and numerical examples are presented to validate the proposed methodology.

Space shuttle orbiter reaction control system jet interaction study

NASA Technical Reports Server (NTRS)

Rausch, J. R.

1975-01-01

The space shuttle orbiter has forward mounted and rear mounted Reaction Control Systems (RCS) which are used for orbital maneuvering and also provide control during entry and abort maneuvers in the atmosphere. The effects of interaction between the RCS jets and the flow over the vehicle in the atmosphere are studied. Test data obtained in the NASA Langley Research Center 31 inch continuous flow hypersonic tunnel at a nominal Mach number of 10.3 is analyzed. The data were obtained with a 0.01 scale force model with aft mounted RCS nozzles mounted on the sting off of the force model balance. The plume simulations were accomplished primarily using air in a cold gas simulation through scaled nozzles, however, various cold gas mixtures of Helium and Argon were also tested. The effect of number of nozzles was tested as were limited tests of combined controls. The data show that RCS nozzle exit momentum ratio is the primary correlating parameter for effects where the plume impinges on an adjacent surface and mass flow ratio is the parameter where the plume interaction is primarily with the external stream. An analytic model of aft mounted RCS units was developed in which the total reaction control moments are the sum of thrust, impingement, interaction, and cross-coupling terms.

UCAV path planning in the presence of radar-guided surface-to-air missile threats

NASA Astrophysics Data System (ADS)

Zeitz, Frederick H., III

This dissertation addresses the problem of path planning for unmanned combat aerial vehicles (UCAVs) in the presence of radar-guided surface-to-air missiles (SAMs). The radars, collocated with SAM launch sites, operate within the structure of an Integrated Air Defense System (IADS) that permits communication and cooperation between individual radars. The problem is formulated in the framework of the interaction between three sub-systems: the aircraft, the IADS, and the missile. The main features of this integrated model are: The aircraft radar cross section (RCS) depends explicitly on both the aspect and bank angles; hence, the RCS and aircraft dynamics are coupled. The probabilistic nature of IADS tracking is accounted for; namely, the probability that the aircraft has been continuously tracked by the IADS depends on the aircraft RCS and range from the perspective of each radar within the IADS. Finally, the requirement to maintain tracking prior to missile launch and during missile flyout are also modeled. Based on this model, the problem of UCAV path planning is formulated as a minimax optimal control problem, with the aircraft bank angle serving as control. Necessary conditions of optimality for this minimax problem are derived. Based on these necessary conditions, properties of the optimal paths are derived. These properties are used to discretize the dynamic optimization problem into a finite-dimensional, nonlinear programming problem that can be solved numerically. Properties of the optimal paths are also used to initialize the numerical procedure. A homotopy method is proposed to solve the finite-dimensional, nonlinear programming problem, and a heuristic method is proposed to improve the discretization during the homotopy process. Based upon the properties of numerical solutions, a method is proposed for parameterizing and storing information for later recall in flight to permit rapid replanning in response to changing threats. Illustrative examples are presented that confirm the standard flying tactics of "denying range, aspect, and aim," by yielding flight paths that "weave" to avoid long exposures of aspects with large RCS.

A new polarimetric active radar calibrator and calibration technique

NASA Astrophysics Data System (ADS)

Tang, Jianguo; Xu, Xiaojian

2015-10-01

Polarimetric active radar calibrator (PARC) is one of the most important calibrators with high radar cross section (RCS) for polarimetry measurement. In this paper, a new double-antenna polarimetric active radar calibrator (DPARC) is proposed, which consists of two rotatable antennas with wideband electromagnetic polarization filters (EMPF) to achieve lower cross-polarization for transmission and reception. With two antennas which are rotatable around the radar line of sight (LOS), the DPARC provides a variety of standard polarimetric scattering matrices (PSM) through the rotation combination of receiving and transmitting polarization, which are useful for polarimatric calibration in different applications. In addition, a technique based on Fourier analysis is proposed for calibration processing. Numerical simulation results are presented to demonstrate the superior performance of the proposed DPARC and processing technique.

Oblique view of the Orbiter Discovery from an elevated platform ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Oblique view of the Orbiter Discovery from an elevated platform in the Vehicle Assembly Building at NASA's Kennedy Space Center. Note the Forward Reaction Control System (RCS) Module from the forward section and the Orbiter Maneuvering System (OMS)/RCS pods from the aft section have been removed. Ground support equipment called Strongbacks are attached to the payload bay doors and the Flight Deck windows have been covered by ground support equipment. Also note the scale figure standing by the Orbiter. - Space Transportation System, Orbiter Discovery (OV-103), Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Aircraft Wake RCS Measurement

NASA Technical Reports Server (NTRS)

Gilson, William H.

1994-01-01

A series of multi-frequency radar measurements of aircraft wakes at altitudes of 5,000 to 25,00 ft. were performed at Kwajalein, R.M.I., in May and June of 1990. Two aircraft were tested, a Learjet 35 and a Lockheed C-5A. The cross-section of the wake of the Learjet was too small for detection at Kwajalein. The wake of the C-5A, although also very small, was detected and measured at VHF, UHF, L-, S-, and C-bands, at distances behind the aircraft ranging from about one hundred meters to tens of kilometers. The data suggest that the mechanism by which aircraft wakes have detectable radar signatures is, contrary to previous expectations, unrelated to engine exhaust but instead due to turbulent mixing by the wake vortices of pre-existing index of refraction gradients in the ambient atmosphere. These measurements were of necessity performed with extremely powerful and sensitive instrumentation radars, and the wake cross-section is too small for most practical applications.

Aircraft wake RCS measurement

NASA Astrophysics Data System (ADS)

Gilson, William H.

1994-07-01

A series of multi-frequency radar measurements of aircraft wakes at altitudes of 5,000 to 25,00 ft. were performed at Kwajalein, R.M.I., in May and June of 1990. Two aircraft were tested, a Learjet 35 and a Lockheed C-5A. The cross-section of the wake of the Learjet was too small for detection at Kwajalein. The wake of the C-5A, although also very small, was detected and measured at VHF, UHF, L-, S-, and C-bands, at distances behind the aircraft ranging from about one hundred meters to tens of kilometers. The data suggest that the mechanism by which aircraft wakes have detectable radar signatures is, contrary to previous expectations, unrelated to engine exhaust but instead due to turbulent mixing by the wake vortices of pre-existing index of refraction gradients in the ambient atmosphere. These measurements were of necessity performed with extremely powerful and sensitive instrumentation radars, and the wake cross-section is too small for most practical applications.

Infrared sensor and window system issues

NASA Astrophysics Data System (ADS)

Hargraves, Charles H., Jr.; Martin, James M.

1992-12-01

EO/IR windows are a significant challenge for the weapon system sensor designer who must design for high EO performance, low radar cross section (RCS), supersonic flight, durability, producibility and affordable initial and life cycle costs. This is particularly true in the 8 to 12 micron IR band at which window materials and coating choices are limited by system design requirements. The requirements also drive the optimization of numerous mechanical, optical, materials, and electrical parameters. This paper addresses the EO/IR window as a system design challenge. The interrelationship of the optical, mechanical, and system design processes are examined. This paper presents a summary of the test results, trade studies and analyses that were performed for multi-segment, flight-worthy optical windows with superior optical performance at subsonic and supersonic aircraft velocities and reduced radar cross section. The impact of the window assembly on EO system modulation transfer function (MTF) and sensitivity will be discussed. The use of conductive coatings for shielding/signature control will be discussed.

High-frequency techniques for RCS prediction of plate geometries

NASA Technical Reports Server (NTRS)

Balanis, Constantine A.; Polka, Lesley A.

1992-01-01

The principal-plane scattering from perfectly conducting and coated strips and rectangular plates is examined. Previous reports have detailed Geometrical Theory of Diffraction/Uniform Theory of Diffraction (GTD/UTD) solutions for these geometries. The GTD/UTD solution for the perfectly conducting plate yields monostatic radar cross section (RCS) results that are nearly identical to measurements and results obtained using the Moment Method (MM) and the Extended Physical Theory of Diffraction (EPTD). This was demonstrated in previous reports. The previous analysis is extended to bistatic cases. GTD/UTD results for the principal-plane scattering from a perfectly conducting, infinite strip are compared to MM and EPTD data. A comprehensive overview of the advantages and disadvantages of the GTD/UTD and of the EPTD and a detailed analysis of the results from both methods are provided. Several previous reports also presented preliminary discussions and results for a GTD/UTD model of the RCS of a coated, rectangular plate. Several approximations for accounting for the finite coating thickness, plane-wave incidence, and far-field observation were discussed. Here, these approximations are replaced by a revised wedge diffraction coefficient that implicitly accounts for a coating on a perfect conductor, plane-wave incidence, and far-field observation. This coefficient is computationally more efficient than the previous diffraction coefficient because the number of Maliuzhinets functions that must be calculated using numerical integration is reduced by a factor of 2. The derivation and the revised coefficient are presented in detail for the hard polarization case. Computations and experimental data are also included. The soft polarization case is currently under investigation.

Flexible manipulation of terahertz wave reflection using polarization insensitive coding metasurfaces.

PubMed

Jiu-Sheng, Li; Ze-Jiang, Zhao; Jian-Quan, Yao

2017-11-27

In order to extend to 3-bit encoding, we propose notched-wheel structures as polarization insensitive coding metasurfaces to control terahertz wave reflection and suppress backward scattering. By using a coding sequence of "00110011…" along x-axis direction and 16 × 16 random coding sequence, we investigate the polarization insensitive properties of the coding metasurfaces. By designing the coding sequences of the basic coding elements, the terahertz wave reflection can be flexibly manipulated. Additionally, radar cross section (RCS) reduction in the backward direction is less than -10dB in a wide band. The present approach can offer application for novel terahertz manipulation devices.

Three-dimensional radar imaging techniques and systems for near-field applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheen, David M.; Hall, Thomas E.; McMakin, Douglas L.

2016-05-12

The Pacific Northwest National Laboratory has developed three-dimensional holographic (synthetic aperture) radar imaging techniques and systems for a wide variety of near-field applications. These applications include radar cross-section (RCS) imaging, personnel screening, standoff concealed weapon detection, concealed threat detection, through-barrier imaging, ground penetrating radar (GPR), and non-destructive evaluation (NDE). Sequentially-switched linear arrays are used for many of these systems to enable high-speed data acquisition and 3-D imaging. In this paper, the techniques and systems will be described along with imaging results that demonstrate the utility of near-field 3-D radar imaging for these compelling applications.

Optimized multilayered wideband absorbers with graded fractal FSS

NASA Astrophysics Data System (ADS)

Vinoy, K. J.; Jose, K. A.; Varadan, Vijay K.; Varadan, Vasundara V.

2001-08-01

Various approaches have been followed for the reduction of radar cross section (RCS), especially of aircraft and missiles. In this paper we present the use of multiple layers of FSS-like fractal geometries printed on dielectric substrates for the same goal. The experimental results shown here indicate 15 dB reduction in the reflection of a flat surface, by the use of this configuration with low loss dielectrics. An extensive optimization scheme is required for extending the angle coverage as well as the bandwidth of the absorber. A brief investigation of such a scheme involving genetic algorithm for this purpose is also presented here.

The APL RCS (Radar Cross Section)/Statistics Code Description, Illustrations of Output, and User’s Guide.

DTIC Science & Technology

1984-01-01

to travel - I henry ,iI s I) rlat, i ed. I- o..n. RIdnd,. 1-243 D1962);. inlg-wave phenomena and wedges (with straight 1191). "I edgel). L. I-. Knioi...a - b and outer a, minor radius b, and length radius a + b. L. TWAVE pL,g Traveling Wave-defines a DIHED a,b,c Dihedral -defines a 90 di- traveling ...99203 GO TO 120 9930) C 99400 C "TWAVE" - TRAVELING WAVE 9950b 330 CALL TWAVE 9900 GO TO 120 9970) C 9980) C "DINED" - DIHEDRAL BOB0) 340 CALL DIHED

Reappraisal of the sequence boundary in time and space: Case and considerations for an SU (subaerial unconformity) that is not a sediment bypass surface, a time barrier, or an unconformity

NASA Astrophysics Data System (ADS)

Holbrook, John M.; Bhattacharya, Janok P.

2012-07-01

The sequence-bounding unconformity bears the key defining traits of being "a surface separating younger from older strata, along which there is evidence of subaerial erosional truncation … or subaerial exposure, with a significant hiatus indicated (Van Wagoner et al., 1988)." This subaerial component of sequence boundaries (subaerial unconformity—SU) is also broadly considered to form as a topographic surface of sediment bypass, carved during relative sea level fall and buried by backfilling during relative sea level rise. Accordingly, the SU is commonly presumed to record an approximate time barrier, which separates older from younger strata along its full length. In this paper we show that regional composite scour (RCS) surfaces that are traditionally mapped as an integral component of the SU were never a single subaerial topographic surface characterized by sediment bypass, are not unconformities, do not record an effective time barrier, and form diachronously at the channel-belt scale over the entire fall to rise of a base-level cycle. These RCS surfaces, and by inference the SU surfaces they comprise, thus do not fully fit key defining characteristics embodied in the conceptual sequence boundary. Flume observations and field data show that the RCS is buried by fluvial sediment simultaneously as it is scoured. Accordingly, the RCS is perennially covered with stored sediment during formation, is only exposed as a subaerial topographic surface at the local place and time where it is undergoing active growth, and forms over the duration of local marine drainage during a relative sea-level cycle. This "cut-and-cover" model differs greatly from more established "bypass" models, which assume that the RCS was roughly sediment free and subaerially exposed for long durations of incision during regression and thus preserves a significant depositional hiatus upon later burial. Instead, the RCS may commonly and locally record a hiatus more typical of a facies-bounding diastem without a lacuna significantly greater than that of surfaces within the strata it binds. Fragments of fluvial strata may commonly and sporadically be preserved above the RCS that are older than underlying marine units overrun by this surface. Consequently, the RCS is not an effective time barrier. Lateral planation by migrating and avulsing channels as the RCS expands laterally after nucleation can place younger fluvial strata over much older units, which means that this surface is also composite and highly diachronous laterally at the scale of channel belts. The cut-and-cover model has additional implications not captured by the bypass model. First, significant sediments may be stored within fluvial strata above the RCS during regression that are not available for contemporary falling stage and lowstand marine shorelines. This can result in marine sediment starvation, particularly of the sand fraction, and in extreme cases can result in sand autodetachment and an absence of regressive marine reservoir sandstones. Second, cutting of the RCS co-generates a suprafluvial surface above the covering fluvial strata during regression that may be used as a mappable proxy for the conceptual maximum regressive surface (MRS). The MRS may be raised above this surface locally by low-accommodation aggradation during lowstand normal regression, but in either case preserves an approximate time line where not reworked during later transgression. Third, valley development across the RCS does not exclusively form by landward knickpoint growth, and may include complexly formed and potentially cross-cutting buffer valleys. SU valley incision can be divided into four modes, which include denudation, structural, buttress, and buffer valley components, which may work together locally and tend to have variable importance along the shore-to-hinterland profile. Although the RCS is not a good rock proxy for the conceptual sequence boundary it remains a very mappable surface which may separate facies of potentially very different origin and reservoir quality. The RCS is also inseparable from the SU and typically the only terrestrial erosional surface of extent in most short-duration sequences. Its nullification as a sequence boundary would mean abandonment of depositional sequence stratigraphy as a correlation and interpretive tool within these sections. An alternative to abandonment of the SU as a sequence boundary is to loosen the definition of a sequence boundary to 'a discrete surface of erosional truncation carved landward of contemporary shorelines that is traceable beyond the scale of a single valley or comparable local system, and its correlative surfaces of conformity and/or non-deposition', and continue its use as before.

Wide band design on the scaled absorbing material filled with flaky CIPs

NASA Astrophysics Data System (ADS)

Xu, Yonggang; Yuan, Liming; Gao, Wei; Wang, Xiaobing; Liang, Zichang; Liao, Yi

2018-02-01

The scaled target measurement is an important method to get the target characteristic. Radar absorbing materials are widely used in the low detectable target, considering the absorbing material frequency dispersion characteristics, it makes designing and manufacturing scaled radar absorbing materials on the scaled target very difficult. This paper proposed a wide band design method on the scaled absorbing material of the thin absorption coating with added carbonyl iron particles. According to the theoretical radar cross section (RCS) of the plate, the reflection loss determined by the permittivity and permeability was chosen as the main design factor. Then, the parameters of the scaled absorbing materials were designed using the effective medium theory, and the scaled absorbing material was constructed. Finally, the full-size coating plate and scaled coating plates (under three different scale factors) were simulated; the RCSs of the coating plates were numerically calculated and measured at 4 GHz and a scale factor of 2. The results showed that the compensated RCS of the scaled coating plate was close to that of the full-size coating plate, that is, the mean deviation was less than 0.5 dB, and the design method for the scaled material was very effective.

Hardware test program for evaluation of baseline range/range rate sensor concept

NASA Technical Reports Server (NTRS)

Pernic, E.

1985-01-01

The test program Phase II effort provides additional design information in terms of range and range rate (R/R) sensor performance when observing and tracking a typical spacecraft target. The target used in the test program was a one-third scale model of the Hubble Space Telescope (HST) available at the MSFC test site where the tests were performed. A modified Bendix millimeter wave radar served as the R/R sensor test bed for evaluation of range and range rate tracking performance, and generation of radar signature characteristics of the spacecraft target. A summary of program test results and conclusions are presented along with detailed description of the Bendix test bed radar with accompaning instrumentation. The MSFC test site and facilities are described. The test procedures used to establish background levels, and the calibration procedures used in the range accuracy tests and RCS (radar cross section) signature measurements, are presented and a condensed version of the daily log kept during the 5 September through 17 September test period is also presented. The test program results are given starting with the RCS signature measurements, then continuing with range measurement accuracy test results and finally the range and range rate tracking accuracy test results.

Smart skin spiral antenna with chiral absorber

NASA Astrophysics Data System (ADS)

Varadan, Vijay K.; Varadan, Vasundara V.

1995-05-01

Recently there has been considerable interest toward designing 'smart skins' for aircraft. The smart skin is a composite layer which may contain conformal radars, conformal microstrip antennas or spiral antennas for electromagnetic applications. These embedded antennas will give rise to very low radar cross section (RCS) or can be completely 'hidden' to tracking radar. In addition, they can be used to detect, monitor or even jam other unwanted electromagnetic field signatures. This paper is designed to address some technical advances made to reduce the size of spiral antennas using tunable dielectric materials and chiral absorbers. The purpose is to design, develop and fabricate a thin, wideband, conformal spiral antenna architecture that is structurally integrable and which uses advanced Penn State dielectric and absorber materials to achieve wideband ground planes, and together with low RCS. Traditional practice has been to design radome and antenna as separate entities and then resolve any interface problems during an integration phase. A structurally integrable conformal antenna, however, demands that the functional components be highly integrated both conceptually and in practice. Our concept is to use the lower skin of the radome as a substrate on which the radiator can be made using standard photolithography, thick film or LTCC techniques.

The Propagation and Scattering of EM Waves in Electrically Large Ducts

NASA Astrophysics Data System (ADS)

Khan, Saeed Mahmood

The electromagnetic scattering from large arbitrarily shaped ducts with complex termination is studied here by a hybrid technique. The propagation of electromagnetic waves in the duct is analyzed in terms of an approximate modal solution. A finite difference technique is employed for computing the reflection characteristics of the complex terminations. Both solutions are combined using the unimoment method. The analysis here is carried out for monostatic RCS and considers only fields backscattered from inside the cavity. Rim-diffraction has been left out. The procedure offers such advantages as in that it is not necessary to find complicated Green's functions, which may not be readily available, when compared with the integral equation method. Hybridization performed by combining an approximate modal technique with a finite difference one makes the scheme numerically efficient. From a computational EM point of view, it brings together a whole spectrum of techniques associated with high frequency modal analysis, Fourier Methods, Radar Cross Section and Scattering, finite difference solution and the Unimoment Method. The practical application of this technique may range from the study of RCS scattered from jet inlets of radar evasive aircraft to submarine communication waveguides.

Xpatch prediction improvements to support multiple ATR applications

NASA Astrophysics Data System (ADS)

Andersh, Dennis J.; Lee, Shung W.; Moore, John T.; Sullivan, Douglas P.; Hughes, Jeff A.; Ling, Hao

1998-08-01

This paper describes an electromagnetic computer prediction code for generating radar cross section (RCS), time-domain signature sand synthetic aperture radar (SAR) images of realistic 3D vehicles. The vehicle, typically an airplane or a ground vehicle, is represented by a computer-aided design (CAD) file with triangular facets, IGES curved surfaces, or solid geometries.The computer code, Xpatch, based on the shooting-and-bouncing-ray technique, is used to calculate the polarimetric radar return from the vehicles represented by these different CAD files. Xpatch computers the first- bounce physical optics (PO) plus the physical theory of diffraction (PTD) contributions. Xpatch calculates the multi-bounce ray contributions by using geometric optics and PO for complex vehicles with materials. It has been found that the multi-bounce calculations, the radar return in typically 10 to 15 dB too low. Examples of predicted range profiles, SAR, imagery, and RCS for several different geometries are compared with measured data to demonstrate the quality of the predictions. Recent enhancements to Xpatch include improvements for millimeter wave applications and hybridization with finite element method for small geometric features and augmentation of additional IGES entities to support trimmed and untrimmed surfaces.

Efficient free energy calculations by combining two complementary tempering sampling methods.

PubMed

Xie, Liangxu; Shen, Lin; Chen, Zhe-Ning; Yang, Mingjun

2017-01-14

Although energy barriers can be efficiently crossed in the reaction coordinate (RC) guided sampling, this type of method suffers from identification of the correct RCs or requirements of high dimensionality of the defined RCs for a given system. If only the approximate RCs with significant barriers are used in the simulations, hidden energy barriers with small to medium height would exist in other degrees of freedom (DOFs) relevant to the target process and consequently cause the problem of insufficient sampling. To address the sampling in this so-called hidden barrier situation, here we propose an effective approach to combine temperature accelerated molecular dynamics (TAMD), an efficient RC-guided sampling method, with the integrated tempering sampling (ITS), a generalized ensemble sampling method. In this combined ITS-TAMD method, the sampling along the major RCs with high energy barriers is guided by TAMD and the sampling of the rest of the DOFs with lower but not negligible barriers is enhanced by ITS. The performance of ITS-TAMD to three systems in the processes with hidden barriers has been examined. In comparison to the standalone TAMD or ITS approach, the present hybrid method shows three main improvements. (1) Sampling efficiency can be improved at least five times even if in the presence of hidden energy barriers. (2) The canonical distribution can be more accurately recovered, from which the thermodynamic properties along other collective variables can be computed correctly. (3) The robustness of the selection of major RCs suggests that the dimensionality of necessary RCs can be reduced. Our work shows more potential applications of the ITS-TAMD method as the efficient and powerful tool for the investigation of a broad range of interesting cases.

Efficient free energy calculations by combining two complementary tempering sampling methods

NASA Astrophysics Data System (ADS)

Xie, Liangxu; Shen, Lin; Chen, Zhe-Ning; Yang, Mingjun

2017-01-01

Although energy barriers can be efficiently crossed in the reaction coordinate (RC) guided sampling, this type of method suffers from identification of the correct RCs or requirements of high dimensionality of the defined RCs for a given system. If only the approximate RCs with significant barriers are used in the simulations, hidden energy barriers with small to medium height would exist in other degrees of freedom (DOFs) relevant to the target process and consequently cause the problem of insufficient sampling. To address the sampling in this so-called hidden barrier situation, here we propose an effective approach to combine temperature accelerated molecular dynamics (TAMD), an efficient RC-guided sampling method, with the integrated tempering sampling (ITS), a generalized ensemble sampling method. In this combined ITS-TAMD method, the sampling along the major RCs with high energy barriers is guided by TAMD and the sampling of the rest of the DOFs with lower but not negligible barriers is enhanced by ITS. The performance of ITS-TAMD to three systems in the processes with hidden barriers has been examined. In comparison to the standalone TAMD or ITS approach, the present hybrid method shows three main improvements. (1) Sampling efficiency can be improved at least five times even if in the presence of hidden energy barriers. (2) The canonical distribution can be more accurately recovered, from which the thermodynamic properties along other collective variables can be computed correctly. (3) The robustness of the selection of major RCs suggests that the dimensionality of necessary RCs can be reduced. Our work shows more potential applications of the ITS-TAMD method as the efficient and powerful tool for the investigation of a broad range of interesting cases.

Simultaneous LC-MS/MS determination of JWH-210, RCS-4, ∆(9)-tetrahydrocannabinol, and their main metabolites in pig and human serum, whole blood, and urine for comparing pharmacokinetic data.

PubMed

Schaefer, Nadine; Kettner, Mattias; Laschke, Matthias W; Schlote, Julia; Peters, Benjamin; Bregel, Dietmar; Menger, Michael D; Maurer, Hans H; Ewald, Andreas H; Schmidt, Peter H

2015-05-01

A series of new synthetic cannabinoids (SC) has been consumed without any toxicological testing. For example, pharmacokinetic data have to be collected from forensic toxicological case work and/or animal studies. To develop a corresponding model for assessing such data, samples of controlled pig studies with two selected SC (JWH-210, RCS-4) and, as reference, ∆(9)-tetrahydrocannabinol (THC) should be analyzed as well as those of human cases. Therefore, a method for determination of JWH-210, RCS-4, THC, and their main metabolites in pig and human serum, whole blood, and urine samples is presented. Specimens were analyzed by liquid-chromatography tandem mass spectrometry and multiple-reaction monitoring with three transitions per compound. Full validation was carried out for the pig specimens and cross-validation for the human specimens concerning precision and bias. For the pig studies, the limits of detection were between 0.05 and 0.50 ng/mL in serum and whole blood and between 0.05 and 1.0 ng/mL in urine, the lower limits of quantification between 0.25 and 1.0 ng/mL in serum and 0.50 and 2.0 ng/mL in whole blood and urine, and the intra- and interday precision values lower than 15% and bias values within ±15%. The applicability was tested with samples taken from a pharmacokinetic pilot study with pigs following intravenous administration of a mixture of 200 μg/kg body mass dose each of JWH-210, RCS-4, and THC. The cross-validation data for human serum, whole blood, and urine showed that this approach should also be suitable for human specimens, e.g., of clinical or forensic cases.

Conserved aspartate and lysine residues of RcsB are required for amylovoran biosynthesis, virulence, and DNA binding in Erwinia amylovora.

PubMed

Ancona, Veronica; Chatnaparat, Tiyakhon; Zhao, Youfu

2015-08-01

In Erwinia amylovora, the Rcs phosphorelay system is essential for amylovoran production and virulence. To further understand the role of conserved aspartate residue (D56) in the phosphor receiver (PR) domain and lysine (K180) residue in the function domain of RcsB, amino acid substitutions of RcsB mutant alleles were generated by site-directed mutagenesis and complementation of various rcs mutants were performed. A D56E substitution of RcsB, which mimics the phosphorylation state of RcsB, complemented the rcsB mutant, resulting in increased amylovoran production and gene expression, reduced swarming motility, and restored pathogenicity. In contrast, D56N and K180A or K180Q substitutions of RcsB did not complement the rcsB mutant. Electrophoresis mobility shift assays showed that D56E, but not D56N, K180Q and K180A substitutions of RcsB bound to promoters of amsG and flhD, indicating that both D56 and K180 are required for DNA binding. Interestingly, the RcsBD56E allele could also complement rcsAB, rcsBC and rcsABCD mutants with restored virulence and increased amylovoran production, indicating that RcsB phosphorylation is essential for virulence of E. amylovora. In addition, mutations of T904 and A905, but not phosphorylation mimic mutation of D876 in the PR domain of RcsC, constitutively activate the Rcs system, suggesting that phosphor transfer is required for activating the Rcs system and indicating both A905 and T904 are required for the phosphatase activity of RcsC. Our results demonstrated that RcsB phosphorylation and dephosphorylation, phosphor transfer from RcsC are essential for the function of the Rcs system, and also suggested that constitutive activation of the Rcs system could reduce the fitness of E. amylovora.

Genome expression analyses revealing the modulation of the Salmonella Rcs regulon by the attenuator IgaA.

PubMed

Mariscotti, Javier F; García-del Portillo, Francisco

2009-03-01

Intracellular growth attenuator A (IgaA) was identified as a Salmonella enterica regulator limiting bacterial growth inside fibroblasts. Genetic evidence further linked IgaA to repression of the RcsCDB regulatory system, which responds to envelope stress. How IgaA attenuates this system is unknown. Here, we present genome expression profiling data of S. enterica serovar Typhimurium igaA mutants grown at high osmolarity and displaying exacerbated Rcs responses. Transcriptome data revealed that IgaA attenuates gene expression changes requiring phosphorylated RcsB (RcsB~P) activity. Some RcsB-regulated genes, yciGFE and STM1862 (pagO)-STM1863-STM1864, were equally expressed in wild-type and igaA strains, suggesting a maximal expression at low levels of RcsB ~P. Other genes, such as metB, ypeC, ygaC, glnK, glnP, napA, glpA, and nirB, were shown for the first time and by independent methods to be regulated by the RcsCDB system. Interestingly, IgaA-deficient strains with reduced RcsC or RcsD levels exhibited different Rcs responses and distinct virulence properties. spv virulence genes were differentially expressed in most of the analyzed strains. spvA expression required RcsB and IgaA but, unexpectedly, was also impaired upon stimulation of the RcsC-->RcsD-->RcsB phosphorelay. Overproduction of either RcsB(+) or a nonphosphorylatable RcsB(D56Q) variant in strains displaying low spvA expression unveiled that both dephosphorylated RcsB and RcsB~P are required for optimal spvA expression. Taken together, our data support a model with IgaA attenuating the RcsCDB system by favoring the switch of RcsB~P to the dephosphorylated state. This role of IgaA in constantly fine-tuning the RcsB~P/RcsB ratio may ensure the proper expression of important virulence factors, such as the Spv proteins.

Radar sensitivity to human heartbeats and respiration

NASA Astrophysics Data System (ADS)

Aardal, Øyvind; Brovoll, Sverre; Paichard, Yoann; Berger, Tor; Lande, Tor Sverre; Hamran, Svein-Erik

2015-05-01

Human heartbeats and respiration can be detected from a distance using radar. This can be used for medical applications and human being detection. It is useful to have a system independent measure of how detectable the vital signs are. In radar applications, the Radar Cross Section (RCS) is normally used to characterize the detectability of an object. Since the human vital signs are seen by the radar as movements of the torso, the modulations in the person RCS can be used as a system independent measure of the vital signs detectability. In this paper, measurements of persons seated in an anechoic chamber are presented. The measurements were calibrated using empty room and a metallic calibration sphere. A narrowband radar operating at frequencies from 500 MHz to 18 GHz in discrete steps was used. A turntable provided measurements at precise aspect angles all around the person under test. In an I & Q receiver, the heartbeat and respiration modulation is a combination of amplitude and phase mod- modulations. The measurements were filtered, leaving the modulations from the vital signs in the radar recordings. The procedure for RCS computation was applied to these filtered data, capturing the complex signatures. It was found that both the heartbeat and respiration detectability increase with increasing frequency. The heartbeat signatures are almost equal from the front and the back, while being almost undetectable from the sides of the person. The respiration signatures are slightly higher from the front than from the back, and smaller from the sides. The signature measurements presented in this paper provide an objective system independent measure of the detectability of human vital signs as a function of frequency and aspect angle. These measures are useful for example in system design and in assessing real measurement scenarios.

Flood Identification from Satellite Images Using Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Chang, L.; Kao, I.; Shih, K.

2011-12-01

Typhoons and storms hit Taiwan several times every year and they cause serious flood disasters. Because the rivers are short and steep, and their flows are relatively fast with floods lasting only few hours and usually less than one day. Flood identification can provide the flood disaster and extent information to disaster assistance and recovery centers. Due to the factors of the weather, it is not suitable for aircraft or traditional multispectral satellite; hence, the most appropriate way for investigating flooding extent is to use Synthetic Aperture Radar (SAR) satellite. In this study, back-propagation neural network (BPNN) model and multivariate linear regression (MLR) model are built to identify the flooding extent from SAR satellite images. The input variables of the BPNN model are Radar Cross Section (RCS) value and mean of the pixel, standard deviation, minimum and maximum of RCS values among its adjacent 3×3 pixels. The MLR model uses two images of the non-flooding and flooding periods, and The inputs are the difference between the RCS values of two images and the variances among its adjacent 3×3 pixels. The results show that the BPNN model can perform much better than the MLR model. The correct percentages are more than 80% and 73% in training and testing data, respectively. Many misidentified areas are very fragmented and unrelated. In order to reinforce the correct percentage, morphological image analysis is used to modify the outputs of these identification models. Through morphological operations, most of the small, fragmented and misidentified areas can be correctly assigned to flooding or non-flooding areas. The final results show that the flood identification of satellite images has been improved a lot and the correct percentages increases up to more than 90%.

Use of Laser Speckle Contrast Imaging to Assess Digital Microvascular Function in Primary Raynaud Phenomenon and Systemic Sclerosis: A Comparison Using the Raynaud Condition Score Diary.

PubMed

Pauling, John D; Shipley, Jacqueline A; Hart, Darren J; McGrogan, Anita; McHugh, Neil J

2015-07-01

Evaluate objective assessment of digital microvascular function using laser speckle contrast imaging (LSCI) in a cross-sectional study of patients with primary Raynaud phenomenon (RP) and systemic sclerosis (SSc), comparing LSCI with both infrared thermography (IRT) and subjective assessment using the Raynaud Condition Score (RCS) diary. Patients with SSc (n = 25) and primary RP (n = 18) underwent simultaneous assessment of digital perfusion using LSCI and IRT with a cold challenge on 2 occasions, 2 weeks apart. The RCS diary was completed between assessments. The relationship between objective and subjective assessments of RP was evaluated. Reproducibility of LSCI/IRT was assessed, along with differences between primary RP and SSc, and the effect of sex. There was moderate-to-good correlation between LSCI and IRT (Spearman rho 0.58-0.84, p < 0.01), but poor correlation between objective assessments and the RCS diary (p > 0.05 for all analyses). Reproducibility of IRT and LSCI was moderate at baseline (ICC 0.51-0.63) and immediately following cold challenge (ICC 0.56-0.86), but lower during reperfusion (ICC 0.3-0.7). Neither subjective nor objective assessments differentiated between primary RP and SSc. Men reported lower median daily frequency of RP attacks (0.82 vs 1.93, p = 0.03). Perfusion using LSCI/IRT was higher in men for the majority of assessments. Objective and subjective methods provide differing information on microvascular function in RP. There is good convergent validity of LSCI with IRT and acceptable reproducibility of both modalities. Neither subjective nor objective assessments could differentiate between primary RP and SSc. Influence of sex on subjective and objective assessment of RP warrants further evaluation.

The Rcs phosphorelay system is specific to enteric pathogens/commensals and activates ydeI, a gene important for persistent Salmonella infection of mice

PubMed Central

Erickson, Kimberly D.; Detweiler, Corrella S.

2010-01-01

Summary Bacteria utilize phosphorelay systems to respond to environmental or intracellular stimuli. Salmonella enterica encodes a four-step phosphorelay system that involves two sensor kinase proteins, RcsC and RcsD, and a response regulator, RcsB. The physiological stimulus for Rcs phosphorelay activation is unknown; however, Rcs-regulated genes can be induced in vitro by osmotic shock, low temperature and antimicrobial peptide exposure. In this report we investigate the role of the Rcs pathway using phylogenetic analysis and experimental techniques. Phylogenetic analysis determined that full-length RcsC-and RcsD-like proteins are generally restricted to Enterobacteriaceae species that have an enteric pathogenic or commensal relationship with the host. Experimental data show that RcsD and RcsB, in addition to RcsC, are important for systemic infection in mice and polymyxin B resistance in vitro. To identify Rcs-regulated genes that confer these phenotypes, we took advantage of our observation that RcsA, a transcription factor and binding partner of RcsB, is not required for polymyxin B resistance or survival in mice. S. enterica serovar Typhimurium oligonucleotide microarrays were used to identify 18 loci that are activated by RcsC, RcsD and RcsB but not RcsA. Five of the 18 loci encode genes that contribute to polymyxin B resistance. One of these genes, ydeI, was shown by quantitative real-time PCR to be regulated by the Rcs pathway independently of RcsA. Additionally, the stationary-phase sigma factor, RpoS (sigmaS), regulates ydeI transcription. In vivo infections show that ydeI mutants are out-competed by wild type 10- to 100-fold after oral inoculation, but are only modestly attenuated after intraperitoneal inoculation. These data indicate that ydeI is an Rcs-activated gene that plays an important role in persistent infection of mice, possibly by increasing bacterial resistance to antimicrobial peptides. PMID:17010160

The Rcs phosphorelay system is specific to enteric pathogens/commensals and activates ydeI, a gene important for persistent Salmonella infection of mice.

PubMed

Erickson, Kimberly D; Detweiler, Corrella S

2006-11-01

Bacteria utilize phosphorelay systems to respond to environmental or intracellular stimuli. Salmonella enterica encodes a four-step phosphorelay system that involves two sensor kinase proteins, RcsC and RcsD, and a response regulator, RcsB. The physiological stimulus for Rcs phosphorelay activation is unknown; however, Rcs-regulated genes can be induced in vitro by osmotic shock, low temperature and antimicrobial peptide exposure. In this report we investigate the role of the Rcs pathway using phylogenetic analysis and experimental techniques. Phylogenetic analysis determined that full-length RcsC- and RcsD-like proteins are generally restricted to Enterobacteriaceae species that have an enteric pathogenic or commensal relationship with the host. Experimental data show that RcsD and RcsB, in addition to RcsC, are important for systemic infection in mice and polymyxin B resistance in vitro. To identify Rcs-regulated genes that confer these phenotypes, we took advantage of our observation that RcsA, a transcription factor and binding partner of RcsB, is not required for polymyxin B resistance or survival in mice. S. enterica serovar Typhimurium oligonucleotide microarrays were used to identify 18 loci that are activated by RcsC, RcsD and RcsB but not RcsA. Five of the 18 loci encode genes that contribute to polymyxin B resistance. One of these genes, ydeI, was shown by quantitative real-time PCR to be regulated by the Rcs pathway independently of RcsA. Additionally, the stationary-phase sigma factor, RpoS (sigmaS), regulates ydeI transcription. In vivo infections show that ydeI mutants are out-competed by wild type 10- to 100-fold after oral inoculation, but are only modestly attenuated after intraperitoneal inoculation. These data indicate that ydeI is an Rcs-activated gene that plays an important role in persistent infection of mice, possibly by increasing bacterial resistance to antimicrobial peptides.

Salmonella Biofilm Development Depends on the Phosphorylation Status of RcsB

PubMed Central

Latasa, Cristina; García, Begoña; Echeverz, Maite; Toledo-Arana, Alejandro; Valle, Jaione; Campoy, Susana; García-del Portillo, Francisco; Solano, Cristina

2012-01-01

The Rcs phosphorelay pathway is a complex signaling pathway involved in the regulation of many cell surface structures in enteric bacteria. In response to environmental stimuli, the sensor histidine kinase (RcsC) autophosphorylates and then transfers the phosphate through intermediary steps to the response regulator (RcsB), which, once phosphorylated, regulates gene expression. Here, we show that Salmonella biofilm development depends on the phosphorylation status of RcsB. Thus, unphosphorylated RcsB, hitherto assumed to be inactive, is essential to activate the expression of the biofilm matrix compounds. The prevention of RcsB phosphorylation either by the disruption of the phosphorelay at the RcsC or RcsD level or by the production of a nonphosphorylatable RcsB allele induces biofilm development. On the contrary, the phosphorylation of RcsB by the constitutive activation of the Rcs pathway inhibits biofilm development, an effect that can be counteracted by the introduction of a nonphosphorylatable RcsB allele. The inhibition of biofilm development by phosphorylated RcsB is due to the repression of CsgD expression, through a mechanism dependent on the accumulation of the small noncoding RNA RprA. Our results indicate that unphosphorylated RcsB plays an active role for integrating environmental signals and, more broadly, that RcsB phosphorylation acts as a key switch between planktonic and sessile life-styles in Salmonella enterica serovar Typhimurium. PMID:22582278

A mutation in rcsB, a gene encoding the core component of the Rcs cascade, enhances the virulence of Edwardsiella tarda.

PubMed

Xu, Ying; Xu, Tingting; Wang, Bin; Dong, Xue; Sheng, Aibo; Zhang, Xiao-Hua

2014-04-01

Edwardsiella tarda, a Gram-negative bacterium of the family Enterobacteriaceae, is the causative agent of the systemic disease edwardsiellosis, which is a major problem in aquaculture industry worldwide. Many virulence-related genes in E. tarda have been investigated, but the Rcs phosphorelay, a two-component pathway, which regulates several cell-surface-associated structures related to invasion and survival in host cells, has not yet been thoroughly studied. In the present study, an rcsB in-frame deletion mutant ΔrcsB was constructed through double-crossover allelic exchange. To complement the rcsB mutation, the ΔrcsB (pACYC184K-rcsB) mutant was constructed by transformation of a low-copy plasmid carrying the intact rcsB into the ΔrcsB mutant of E. tarda. Several virulence-associated characters of the mutants and wild-type strain were tested. Compared with wild-type strain EIB202, biofilm formation decreased significantly in ΔrcsB, while ΔrcsB (pACYC184K-rcsB) recovered the phenotype to some extent. In addition, the capacity for autoagglutination, the percentage of adherence and internalization to Epithelioma papulosum cyprini cells and lethality toward zebrafish embryos significantly increased in ΔrcsB. All these phenomena displayed by mutant ΔrcsB showed a certain degree of recovery, though incomplete, in strain ΔrcsB (pACYC184K-rcsB). Present results indicate that rcsB is involved in regulating the gene expression of virulence factors in E. tarda, as shown in other members of Enterobacteriaceae. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Electromagnetic Scattering from Arbitrarily Shaped Aperture Backed by Rectangular Cavity Recessed in Infinite Ground Plane

NASA Technical Reports Server (NTRS)

Cockrell, C. R.; Beck, Fred B.

1997-01-01

The electromagnetic scattering from an arbitrarily shaped aperture backed by a rectangular cavity recessed in an infinite ground plane is analyzed by the integral equation approach. In this approach, the problem is split into two parts: exterior and interior. The electromagnetic fields in the exterior part are obtained from an equivalent magnetic surface current density assumed to be flowing over the aperture and backed by an infinite ground plane. The electromagnetic fields in the interior part are obtained in terms of rectangular cavity modal expansion functions. The modal amplitudes of cavity modes are determined by enforcing the continuity of the electric field across the aperture. The integral equation with the aperture magnetic current density as an unknown is obtained by enforcing the continuity of magnetic fields across the aperture. The integral equation is then solved for the magnetic current density by the method of moments. The electromagnetic scattering properties of an aperture backed by a rectangular cavity are determined from the magnetic current density. Numerical results on the backscatter radar cross-section (RCS) patterns of rectangular apertures backed by rectangular cavities are compared with earlier published results. Also numerical results on the backscatter RCS patterns of a circular aperture backed by a rectangular cavity are presented.

Low-speed wind-tunnel investigation of the stability and control characteristics of a series of flying wings with sweep angles of 50 deg

NASA Technical Reports Server (NTRS)

Fears, Scott P.; Ross, Holly M.; Moul, Thomas M.

1995-01-01

A wind-tunnel investigation was conducted in the Langley 12-Foot Low-Speed Tunnel to study the low-speed stability and control characteristics of a series of four flying wings over an extended range of angle of attack (-8 deg to 48 deg). Because of the current emphasis on reducing the radar cross section (RCS) of new military aircraft, the planform of each wing was composed of lines swept at a relatively high angle of 50 deg, and all the trailing-edge lines were aligned with one of the two leading edges. Three arrow planforms with different aspect ratios and one diamond planform were tested. The models incorporated leading-edge flaps for improved longitudinal characteristics and lateral stability and had trailing-edge flaps in three segments that were deflected differentially for roll control, symmetrically for pitch control, and in a split fashion for yaw control. Three top body widths and two sizes of twin vertical tails were also tested on each model. A large aerodynamic database was compiled that could be used to evaluate some of the trade-offs involved in the design of a configuration with a reduced RCS and good flight dynamic characteristics.

Low-speed wind-tunnel investigation of the stability and control characteristics of a series of flying wings with sweep angles of 70 deg

NASA Technical Reports Server (NTRS)

Ross, Holly M.; Fears, Scott P.; Moul, Thomas M.

1995-01-01

A wind-tunnel investigation was conducted in the Langley 12-Foot Low-Speed Tunnel to study the low-speed stability and control characteristics of a series of four flying wings over an extended range of angle of attack (-8 deg to 48 deg). Because of the current emphasis on reducing the radar cross section (RCS) of new military aircraft, the planform of each wing was composed of lines swept at a relatively high angle of 70 deg, and all the trailing edges and control surface hinge lines were aligned with one of the two leading edges. Three arrow planforms with different aspect ratios and one diamond planform were tested. The models incorporated leading-edge flaps for improved longitudinal characteristics and lateral stability and had three sets of trailing-edge flaps that were deflected differentially for roll control, symmetrically for pitch control, and in a split fashion for yaw control. Three top body widths and two sizes of twin vertical tails were also tested on each model. A large aerodynamic database was compiled that could be used to evaluate some of the trade-offs involved in the design of a configuration with a reduced RCS and good flight dynamic characteristics.

Wind turbine generators with active radar signature control blades

NASA Astrophysics Data System (ADS)

Tennant, Alan; Chambers, Barry

2004-07-01

The large radar cross section of wind turbine generator (WTG) blades combined with high tip speeds can produce significant Doppler returns when illuminated by a radar. Normally, an air traffic control radar system will filter out large returns from stationary targets, however the Doppler shifts introduced by the WTG are interpreted as moving aircraft that can confuse radar operators and compromise safety. A possible solution to this problem that we are investigating is to incorporate an active layer into the structure of the WTG blades that can be used to dynamically modulate the RCS of the blade return. The active blade can operate in one of two modes: firstly the blade RCS can be modulated to provide a Doppler return that is outside the detectable range of the radar receiver system so that it is rejected: a second mode of operation is to introduce specific coding on to the Doppler returns so that they may be uniquely identified and rejected. The active layer used in the system consists of a frequency selective surface controlled by semiconductor diodes and is a development of techniques that we have developed for active radar absorbers. Results of experimental work using a 10GHz Doppler radar and scale model WTG with active Doppler imparting blades are presented.

Numerical and Experimental Investigation on Electromagnetic Attenuation by Semi-Ellipsoidal Shaped Plasma

NASA Astrophysics Data System (ADS)

He, Xiang; Chen, Jianping; Zhang, Yachun; Chen, Yudong; Zeng, Xiaojun; Tang, Chunmei

2015-10-01

Some reports presented that the radar cross section (RCS) from the radar antenna of military airplanes can be reduced by using a low-temperature plasma screen. This paper gives a numerical and experimental analysis of this RCS-reduction method. The shape of the plasma screen was designed as a semi-ellipsoid in order to make full use of the space in the radar dome. In simulations, we discussed the scattering of the electromagnetic (EM) wave by a perfect electric conductor (PEC) covered with this plasma screen using the finite-difference-time-domain (FDTD) method. The variations of their return loss as a function of wave frequency, plasma density profile, and collision frequency were presented. In the experiments, a semi-ellipsoidal shaped plasma screen was produced. Electromagnetic attenuation of 1.5 GHz EM wave was measured for a radio frequency (RF) power of 5 kW at an argon pressure of 200-1150 Pa. A good agreement is found between simulated and experimental results. It can be confirmed that the plasma screen is useful in applications for stealth of radar antenna. supported by National Natural Science Foundation of China (No. 51107033) and the Fundamental Research Funds for the Central Universities, China (No. 2013B33614)

Characterization of the RcsC sensor kinase from Erwinia amylovora and other Enterobacteria.

PubMed

Wang, Dongping; Korban, Schuyler S; Pusey, P Lawrence; Zhao, Youfu

2011-06-01

RcsC is a hybrid sensor kinase which contains a sensor domain, a histidine kinase domain, and a receiver domain. We have previously demonstrated that, although the Erwinia amylovora rcsC mutant produces more amylovoran than the wild-type (WT) strain in vitro, the mutant remains nonpathogenic on both immature pear fruit and apple plants. In this study, we have comparatively characterized the Erwinia RcsC and its homologs from various enterobacteria. Results demonstrate that expression of the Erwinia rcsC gene suppresses amylovoran production in various amylovoran overproducing WT and mutant strains, thus suggesting the presence of a net phosphatase activity of Erwinia RcsC. Findings have also demonstrated that rcsC homologs from other enterobacteria could not rescue amylovoran production of the Erwinia rcsC mutant in vitro. However, virulence of the Erwinia rcsC mutant is partially restored by rcsC homologs from Pantoea stewartii, Yersinia pestis, and Salmonella enterica but not from Escherichia coli on apple shoots. Domain-swapping experiments have indicated that replacement of the E. coli RcsC sensor domain by those of Erwinia and Yersinia spp. partially restores virulence of the Erwinia rcsC mutant, whereas chimeric constructs containing the sensor domain of E. coli RcsC could not rescue virulence of the Erwinia rcsC mutant on apple. Interestingly, only chimeric constructs containing the histidine kinase and receiver domains of Erwinia RcsC are fully capable of rescuing amylovoran production. These results suggest that the sensor domain of RcsC may be important in regulating bacterial virulence, whereas the activity of the histidine kinase and receiver domains of Erwinia RcsC may be essential for amylovoran production in vitro.

Independent Orbiter Assessment (IOA): Assessment of the reaction control system, volume 5

NASA Technical Reports Server (NTRS)

Prust, Chet D.; Hartman, Dan W.

1988-01-01

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the aft and forward Reaction Control System (RCS) hardware and Electrical Power Distribution and Control (EPD and C), generating draft failure modes and potential critical items. The IOA results were then compared to the proposed Post 51-L NASA FMEA/CIL baseline. This report documents the results of that comparison for the Orbiter RCS hardware and EPD and C systems. Volume 5 contains detailed analysis and superseded analysis worksheets and the NASA FMEA to IOA worksheet cross reference and recommendations.

Impact of coronary collaterals on in-hospital and 5-year mortality after ST-elevation myocardial infarction in the contemporary percutaneous coronary intervention era: a prospective observational study

PubMed Central

Hara, Masahiko; Sakata, Yasuhiko; Nakatani, Daisaku; Suna, Shinichiro; Nishino, Masami; Sato, Hiroshi; Kitamura, Tetsuhisa; Nanto, Shinsuke; Hori, Masatsugu; Komuro, Issei

2016-01-01

Objectives To evaluate the short-term and long-term prognostic impacts of acute phase coronary collaterals to occluded infarct-related arteries (IRA) after ST-elevation myocardial infarction (STEMI) in the percutaneous coronary intervention (PCI) era. Design A prospective observational study. Setting Osaka Acute Coronary Insufficiency Study (OACIS) in Japan. Participants 3340 patients with STEMI from the OACIS database who were admitted to hospitals within 24 hours from the onset and who had a completely occluded IRA. Interventions Patients were divided into 4 groups according to the Rentrop collateral score (RCS) by angiography on admission (RCS-0, no visible collaterals; RCS-1, collaterals without IRA filling; RCS-2, collaterals with partial IRA filling; and RCS-3, collaterals with complete IRA filling). Primary outcome measures In-hospital and 5-year mortality. Results Patients with RCS-0/3 were older than patients with RCS-1/2, and the prevalence of previous myocardial infarction was highest in patients with RCS-3. Median peak creatinine phosphokinase levels decreased as RCS increases (p<0.001), suggesting the acute cardioprotective effects of collaterals. Although RCS-1 and RCS-2 collaterals were associated with better in-hospital mortality (adjusted OR 0.48, p=0.046 and 0.38, p=0.010 for RCS-1 and RCS-2, respectively) and 5-year mortality (adjusted HR 0.53, p=0.004 and 0.46, p<0.001 for RCS-1 and RCS-2, respectively) as compared with R-0, presence of RCS-3 collaterals was not associated with improved in-hospital (adjusted OR 1.35, p=0.331) and 5-year mortality (adjusted HR 0.98, p=0.920), possibly because worse clinical profiles in patients with RCS-3 may mask mortality benefit of coronary collaterals. Conclusions Presence of acute phase coronary collaterals such as RCS-1 and RCS-2 were associated with better in-hospital and 5-year mortality after STEMI in the contemporary PCI era. PMID:27412101

Inverse synthetic aperture radar imagery of a man with a rocket propelled grenade launcher

NASA Astrophysics Data System (ADS)

Tran, Chi N.; Innocenti, Roberto; Kirose, Getachew; Ranney, Kenneth I.; Smith, Gregory

2004-08-01

As the Army moves toward more lightly armored Future Combat System (FCS) vehicles, enemy personnel will present an increasing threat to U.S. soldiers. In particular, they face a very real threat from adversaries using shoulder-launched, rocket propelled grenade (RPG). The Army Research Laboratory has utilized its Aberdeen Proving Ground (APG) turntable facility to collect very high resolution, fully polarimetric Ka band radar data at low depression angles of a man holding an RPG. In this paper, we examine the resulting low resolution and high resolution range profiles; and based on the observed radar cross section (RCS) value, we attempt to determine the utility of Ka band radar for detecting enemy personnel carrying RPG launchers.

Electromagnetic characterization of conformal antennas

NASA Technical Reports Server (NTRS)

Volakis, John L.; Kempel, Leo C.; Alexanian, Angelos; Jin, J. M.; Yu, C. L.; Woo, Alex C.

1992-01-01

The ultimate objective of this project is to develop a new technique which permits an accurate simulation of microstrip patch antennas or arrays with various feed, superstrate and/or substrate configurations residing in a recessed cavity whose aperture is planar, cylindrical or otherwise conformed to the substructure. The technique combines the finite element and boundary integral methods to formulate a system suitable for solution via the conjugate gradient method in conjunction with the fast Fourier transform. The final code is intended to compute both scattering and radiation patterns of the structure with an affordable memory demand. With upgraded capabilities, the four included papers examined the radar cross section (RCS), input impedance, gain, and resonant frequency of several rectangular configurations using different loading and substrate/superstrate configurations.

Quantification of endotoxins in infected root canals and acute apical abscess exudates: monitoring the effectiveness of root canal procedures in the reduction of endotoxins.

PubMed

Sousa, Ezilmara L R; Martinho, Frederico C; Nascimento, Gustavo G; Leite, Fabio R M; Gomes, Brenda P F A

2014-02-01

This clinical study was conducted to measure the endotoxin levels in infected root canals (RCs) and exudates related to acute apical abscesses (AAAs). In addition, the effectiveness of RC procedures in reducing the endotoxin levels in RCs was monitored. Paired samples of infected RCs and exudates from AAAs were collected from 10 subjects by using paper points. RCs samples were collected before (RCS1) and after chemomechanical preparation (CMP) (RCS2), after 17% EDTA (RCS3), and after 30 days of intracanal medication (Ca[OH]2 + chlorhexidine) (RCS4). A turbidimetric kinetic limulus amebocyte lysate assay was used for the measurement of endotoxins. Endotoxins were detected in 100% of the baseline samples of AAAs and RCs (RCS1) with median values of 175 EU/mL and 41.5 EU/mL, respectively (P < .05). After CMP (RCS2), endotoxins were reduced to a median value of 0.54 EU/mL (P < .05). Subsequent irrigation with EDTA (RCS3) failed to present a significant effectiveness in reducing the endotoxin levels (median= 0.37 EU/mL) (P = .07). However, intracanal medication for 30 days (RCS4) reduced endotoxins to median values of 0.03 EU/mL (P < .01). The present study revealed a strong association between the high levels of endotoxins found in AAAs and RCs collected from the same tooth. Moreover, the effectiveness of CMP in reducing the endotoxin levels from RCs in acute endodontic infection was improved by the use of RC medication. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Comprehension of Subject and Object Relative Clauses in a Trilingual Acquisition Context

PubMed Central

Chan, Angel; Chen, Si; Matthews, Stephen; Yip, Virginia

2017-01-01

Chinese relative clauses (RCs) have word order properties that are distinctly rare across languages of the world; such properties provide a good testing ground to tease apart predictions regarding the relative complexity of subject and object RCs in acquisition and processing. This study considers these special word order properties in a multilingual acquisition context, examining how Cantonese(L1)-English(L2)-Mandarin(L3) trilingual children process RCs in two Chinese languages differing in exposure conditions. Studying in an English immersion international school, these trilinguals are also under intensive exposure to English. Comparisons of the trilinguals with their monolingual counterparts are made with a focus on the directionality of cross-linguistic influence. The study considers how various factors such as language exposure, structural overlaps in the target languages, typological distance, and language dominance can account for the linguistic abilities and vulnerabilities exhibited by a group of children in a trilingual acquisition context. Twenty-one trilingual 5- to 6-year-olds completed tests of subject- and object- RC comprehension in all three languages. Twenty-four age-matched Cantonese monolinguals and 24 age-matched Mandarin monolinguals served as comparison groups. Despite limited exposure to Mandarin, the trilinguals performed comparable to the monolinguals. Their Cantonese performance uniquely predicts their Mandarin performance, suggesting positive transfer from L1 Cantonese to L3 Mandarin. In Cantonese, however, despite extensive exposure from birth, the trilinguals comprehended object RCs significantly worse than the monolinguals. Error analyses suggested an English-based head-initial analysis, implying negative transfer from L2 English to L1 Cantonese. Overall, we identified a specific case of bi-directional influence between the first and second/third languages. The trilinguals experience facilitation in processing Mandarin RCs, because parallels and overlaps in both form and function provide a transparent basis for positive transfer from L1 Cantonese to L3 Mandarin. On the other hand, they experience more difficulty in processing object RCs in Cantonese compared to their monolingual peers, because structural overlaps with competing structures from English plus intensive exposure to English lead to negative transfer from L2 English to L1 Cantonese. The findings provide further evidence that head noun assignment in object RCs is especially vulnerable in multilingual Cantonese children when they are under intensive exposure to English. PMID:29056917

Root cortical senescence decreases root respiration, nutrient content and radial water and nutrient transport in barley.

PubMed

Schneider, Hannah M; Wojciechowski, Tobias; Postma, Johannes A; Brown, Kathleen M; Lücke, Andreas; Zeisler, Viktoria; Schreiber, Lukas; Lynch, Jonathan P

2017-08-01

The functional implications of root cortical senescence (RCS) are poorly understood. We tested the hypotheses that RCS in barley (1) reduces the respiration and nutrient content of root tissue; (2) decreases radial water and nutrient transport; and (3) is accompanied by increased suberization to protect the stele. Genetic variation for RCS exists between modern germplasm and landraces. Nitrogen and phosphorus deficiency increased the rate of RCS. Maximal RCS, defined as the disappearance of the entire root cortex, reduced root nitrogen content by 66%, phosphorus content by 63% and respiration by 87% compared with root segments with no RCS. Roots with maximal RCS had 90, 92 and 84% less radial water, nitrate and phosphorus transport, respectively, compared with segments with no RCS. The onset of RCS coincided with 30% greater aliphatic suberin in the endodermis. These results support the hypothesis that RCS reduces root carbon and nutrient costs and may therefore have adaptive significance for soil resource acquisition. By reducing root respiration and nutrient content, RCS could permit greater root growth, soil resource acquisition and resource allocation to other plant processes. RCS merits investigation as a trait for improving the performance of barley, wheat, triticale and rye under edaphic stress. © 2017 John Wiley & Sons Ltd.

Geometrical optics design of a compact range Gregorian subreflector system by the principle of the central ray

NASA Technical Reports Server (NTRS)

Clerici, Giancarlo; Burnside, Walter D.

1989-01-01

In recent years, the compact range has become very popular for measuring Radar Cross Section (RCS) and antenna patterns. The compact range, in fact, offers several advantages due to reduced size, a controlled environment, and privacy. On the other hand, it has some problems of its own, which must be solved properly in order to achieve high quality measurement results. For example, diffraction from the edges of the main reflector corrupts the plane wave in the target zone and creates spurious scattering centers in RCS measurements. While diffraction can be minimized by using rolled edges, the field of an offset single reflector compact range is corrupted by three other errors: the taper of the reflected field, the cross polarization introduced by the tilt of the feed and the aperture blockage introduced by the feed itself. These three errors can be eliminated by the use of a subreflector system. A properly designed subreflector system offers very little aperture blockage, no cross-polarization introduced and a minimization of the taper of the reflected field. A Gregorian configuration has been adopted in order to enclose the feed and the ellipsoidal subreflector in a lower chamber, which is isolated by absorbers from the upper chamber, where the main parabolic reflector and the target zone are enclosed. The coupling between the two rooms is performed through a coupling aperture. The first cut design for such a subreflector system is performed through Geometrical Optics ray tracing techniques (GO), and is greatly simplified by the use of the concept of the central ray introduced by Dragone. The purpose of the GO design is to establish the basic dimensions of the main reflector and subreflector, the size of the primary and secondary illuminating surfaces, the tilt angles of the subreflector and feed, and estimate the feed beamwidth. At the same time, the shape of the coupling aperture is initially determined.

Results of wind tunnel RCS interaction tests on a 0.010-scale space shuttle orbiter model (51-0) in the Calspan Corporation 48-inch hypersonic shock tunnel (test 0A93)

NASA Technical Reports Server (NTRS)

Daileda, J. J.; Marroquin, J.; Rogers, C. E.

1976-01-01

A hypersonic shock tunnel test on a 0.010 scale SSV orbital configuration was performed to determine the effects of RCS jet/flow field interactions on SSV aerodynamic stability and control characteristics at various hypersonic Mach and Reynolds numbers. Flow field interaction data were obtained using pitch and roll jets. In addition, direct impingement data were obtained at a Mach number of zero with the test section pumped down to below 10 microns of mercury pressure.

Fractal Analyses of High-Resolution Cloud Droplet Measurements.

NASA Astrophysics Data System (ADS)

Malinowski, Szymon P.; Leclerc, Monique Y.; Baumgardner, Darrel G.

1994-02-01

Fractal analyses of individual cloud droplet distributions using aircraft measurements along one-dimensional horizontal cross sections through clouds are performed. Box counting and cluster analyses are used to determine spatial scales of inhomogeneity of cloud droplet spacing. These analyses reveal that droplet spatial distributions do not exhibit a fractal behavior. A high variability in local droplet concentration in cloud volumes undergoing mixing was found. In these regions, thin filaments of cloudy air with droplet concentration close to those observed in cloud cores were found. Results suggest that these filaments may be anisotropic. Additional box counting analyses performed for various classes of cloud droplet diameters indicate that large and small droplets are similarly distributed, except for the larger characteristic spacing of large droplets.A cloud-clear air interface defined by a certain threshold of total droplet count (TDC) was investigated. There are indications that this interface is a convoluted surface of a fractal nature, at least in actively developing cumuliform clouds. In contrast, TDC in the cloud interior does not have fractal or multifractal properties. Finally a random Cantor set (RCS) was introduced as a model of a fractal process with an ill-defined internal scale. A uniform measure associated with the RCS after several generations was introduced to simulate the TDC records. Comparison of the model with real TDC records indicates similar properties of both types of data series.

Effect of Root Canal Sealers on Bond Strength of Fiber Posts to Root Dentin Cemented after one Week or six Months

PubMed Central

Ruiz, Lucas; Mongruel Gomes, Giovana; Bittencourt, Bruna; Rutz da Silva, Fabrício; Mongruel Gomes, Osnara Maria; Chidoski Filho, Julio Cezar; Lincoln Calixto, Abraham

2018-01-01

Eugenol-based root canal sealers (RCS) have been widely used by clinicians; however, their effect on resinous materials is still questionable. The objective of this study was to evaluate the influence of RCS at 1 week and 6 months’ post obturation on the bond strength (BS) of glass fiber posts (GFP) to root dentin, using conventional and self-adhesive cementation systems (CS). The roots of 56 extracted human canines, were divided in eight groups (n=7) according to the combination of the following factors: RCS (with or without eugenol-Endofill and Sealer 26, respectively), storage period post obturation and prior GFP cementation (1 week and 6 months) and cementation systems (Variolink II - conventional resin cement or RelyX U200-self-adhesive resin cement). After one week, the specimens were transversely sectioned into six 1-mm-thick disks and were subjected to the push out BS test. The data were subjected to 3-way ANOVA and Tukey’s tests (α=0.05). The BS were not affected by the RCS, neither the CS (P>0.05). Just the period post obturation showed statistically significant differences (P 0.05), where the GFP cemented 6 months after the endodontic treatment showed higher values than those cemented 1 week after it. PMID:29692836

Structural Basis for DNA Recognition by the Two-Component Response Regulator RcsB.

PubMed

Filippova, Ekaterina V; Zemaitaitis, Bozena; Aung, Theint; Wolfe, Alan J; Anderson, Wayne F

2018-02-27

RcsB is a highly conserved transcription regulator of the Rcs phosphorelay system, a complex two-component signal transduction system (N. Majdalani and S. Gottesman, Annu Rev Microbiol 59:379-405, 2005; A. J. Wolfe, Curr Opin Microbiol 13:204-209, 2010, https://doi.org/10.1016/j.mib.2010.01.002; D. J. Clarke, Future Microbiol 5:1173-1184, 2010, https://doi.org/10.2217/fmb.10.83). RcsB plays an important role in virulence and pathogenicity in human hosts by regulating biofilm formation. RcsB can regulate transcription alone or together with its auxiliary transcription regulators by forming heterodimers. This complexity allows RcsB to regulate transcription of more than 600 bacterial genes in response to different stresses (D. Wang et al., Mol Plant Microbe Interact 25:6-17, 2012, https://doi.org/10.1094/MPMI-08-11-0207). Despite increasing knowledge of RcsB importance, molecular mechanisms that drive the ability of RcsB to control transcription of a large number of genes remain unclear. Here, we present crystal structures of unphosphorylated RcsB in complex with the consensus DNA-binding sequence of 22-mer (DNA22) and 18-mer (DNA18) of the flhDC operon from Escherichia coli determined at 3.15- and 3.37-Å resolution, respectively. The results of our structural analysis combined with the results of in vitro binding assays provide valuable insights to the protein regulatory mechanism, demonstrate how RcsB recognizes target DNA sequences, and reveal a unique oligomeric state that allows RcsB to form homo- and heterodimers. This information will help us understand the complex mechanisms of transcriptional regulation by RcsB in bacteria. IMPORTANCE RcsB is a well-studied two-component response regulator of the Rcs phosphorelay system, conserved within the family Enterobacteriaceae , which includes many pathogens. It is a global regulator, controlling more than 5% of bacterial genes associated with capsule biosynthesis, flagellar biogenesis, cell wall biosynthesis, antibiotic resistance, biofilm formation, and virulence in pathogens. Knowledge of RcsB structure represents a unique opportunity to explore mechanisms that regulate the Rcs phosphorelay system and its role in the family Enterobacteriaceae . Copyright © 2018 Filippova et al.

Performance test and verification of an off-the-shelf automated avian radar tracking system.

PubMed

May, Roel; Steinheim, Yngve; Kvaløy, Pål; Vang, Roald; Hanssen, Frank

2017-08-01

Microwave radar is an important tool for observation of birds in flight and represents a tremendous increase in observation capability in terms of amount of surveillance space that can be covered at relatively low cost. Based on off-the-shelf radar hardware, automated radar tracking systems have been developed for monitoring avian movements. However, radar used as an observation instrument in biological research has its limitations that are important to be aware of when analyzing recorded radar data. This article describes a method for exploring the detection capabilities of a dedicated short-range avian radar system used inside the operational Smøla wind-power plant. The purpose of the testing described was to find the maximum detection range for various sized birds, while controlling for the effects of flight tortuosity, flight orientation relative to the radar and ground clutter. The method was to use a dedicated test target in form of a remotely controlled unmanned aerial vehicle (UAV) with calibrated radar cross section (RCS), which enabled the design of virtually any test flight pattern within the area of interest. The UAV had a detection probability of 0.5 within a range of 2,340 m from the radar. The detection performance obtained by the RCS-calibrated test target (-11 dBm 2 , 0.08 m 2 RCS) was then extrapolated to find the corresponding performance of differently sized birds. Detection range depends on system sensitivity, the environment within which the radar is placed and the spatial distribution of birds. The avian radar under study enables continuous monitoring of bird activity within a maximum range up to 2 km dependent on the size of the birds in question. While small bird species may be detected up to 0.5-1 km, larger species may be detected up to 1.5-2 km distance from the radar.

Vision maintenance and retinal apoptosis reduction in RCS rats with Okayama University-type retinal prosthesis (OUReP™) implantation.

PubMed

Alamusi; Matsuo, Toshihiko; Hosoya, Osamu; Tsutsui, Kimiko M; Uchida, Tetsuya

2015-09-01

Photoelectric dye-coupled polyethylene film, designated Okayama University-type retinal prosthesis or OUReP™, generates light-evoked surface electric potentials and stimulates neurons. In this study, the vision was assessed by behavior tests in aged hereditary retinal dystrophic RCS rats with OUReP™, retinal apoptosis and electroretinographic responses were measured in dystrophic eyes with OUReP™. The dye-coupled films, or plain films as a control, were implanted in subretinal space of RCS rats. On behavior tests, RCS rats with dye-coupled films, implanted at the old age of 14 weeks, showed the larger number of head-turning, consistent with clockwise and anticlockwise rotation of a surrounding black-and-white-striped drum, compared with rats with plain films, under the dim (50 lux) and bright (150 lux) conditions in the observation period until the age of 22 weeks (n = 5, P < 0.05, repeated-measure ANOVA). The number of apoptotic cells in retinal sections at the site of dye-coupled film implantation was significantly smaller, compared with the other retinal sites, neighboring the film, or opposite to the film, 5 months after film implantation at the age of 6 weeks (P = 0.0021, Friedman test). The dystrophic eyes of RCS rats with dye-coupled films showed positive responses to maximal light stimulus at a significantly higher rate, compared with the eyes with no treatment (P < 0.05, Chi-square test). Electroretinograms in normal eyes of Wistar rats with dye-coupled or plain films showed significantly decreased amplitudes (n = 14, P < 0.05, repeated-measure ANOVA). In conclusions, vision was maintained in RCS rats with dye-coupled films implanted at the old age. The dystrophic eyes with dye-coupled films showed electroretinographic responses. Five-month film implantation caused no additional retinal changes.

The reduced basis method for the electric field integral equation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fares, M., E-mail: fares@cerfacs.f; Hesthaven, J.S., E-mail: Jan_Hesthaven@Brown.ed; Maday, Y., E-mail: maday@ann.jussieu.f

We introduce the reduced basis method (RBM) as an efficient tool for parametrized scattering problems in computational electromagnetics for problems where field solutions are computed using a standard Boundary Element Method (BEM) for the parametrized electric field integral equation (EFIE). This combination enables an algorithmic cooperation which results in a two step procedure. The first step consists of a computationally intense assembling of the reduced basis, that needs to be effected only once. In the second step, we compute output functionals of the solution, such as the Radar Cross Section (RCS), independently of the dimension of the discretization space, formore » many different parameter values in a many-query context at very little cost. Parameters include the wavenumber, the angle of the incident plane wave and its polarization.« less

Extension of On-Surface Radiation Condition (OSRC) theory to full-vector electromagnetic wave scattering by three-dimensional conducting, dielectric, and coated targets

NASA Astrophysics Data System (ADS)

Taflove, Allen; Umashankar, Korada R.

1993-08-01

This project introduced radiation boundary condition (RBC) and absorbing boundary condition (ABC) theory to the engineering electromagnetics community. An approximate method for obtaining the scattering of 2-D and 3-D bodies, the on-surface radiation condition (OSRC) method, was formulated and validated. RBC's and ABC's were shown to work well at points closer to scatterers than anyone had expected. Finite-difference time domain (FD-TD) methods exploiting these ABC's were pursued for applications in scattering, radiation, penetration, biomedical studies, and nonlinear optics. Multiprocessing supercomputer software was developed for FD-TD, leading to the largest scale detailed electromagnetic wave interaction models ever conducted, including entire jet fighter aircraft modeled for radar cross section (RCS) at UHF frequencies up to 500 MHz.

Foliar uptake of radiocaesium from irrigation water by paddy rice (Oryza sativa): an overlooked pathway in contaminated environments.

PubMed

Uematsu, Shinichiro; Vandenhove, Hildegarde; Sweeck, Lieve; Hees, May Van; Wannijn, Jean; Smolders, Erik

2017-04-01

Flooded (paddy) rice (Oryza sativa) can take up ions from the irrigation water by foliar uptake via the exposed stem base. We hypothesised that the stem base uptake of radiocaesium (RCs) is a pathway for rice grown in RCs-contaminated environments. We developed a bi-compartmental device which discriminates the stem base from root RCs uptake from solutions, thereby using RCs isotopes ( 137 Cs and 134 Cs) with < 2% solution leak between the compartments. Radiocaesium uptake was linear over time (0-24 h). Radiocaesium uptake to the entire plant, expressed per dry weight of the exposed parts, was sixfold higher for the roots than for the exposed stem base. At equal RCs concentrations in both compartments, the exposed stem base and root uptake contributed almost equally to the total shoot RCs concentrations. Reducing potassium supply to the roots not only increased the root RCs uptake but also increased RCs uptake by the stem base. This study was the first to experimentally demonstrate active and internally regulated RCs uptake by the stem base of rice. Scenario calculations for the Fukushima-affected area predict that RCs in irrigation water could be an important source of RCs in rice as indirectly suggested from field data. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Grafting Modification of the Reactive Core-Shell Particles to Enhance the Toughening Ability of Polylactide

PubMed Central

Li, Zhaokun; Song, Shixin; Zhao, Xuanchen; Lv, Xue; Sun, Shulin

2017-01-01

In order to overcome the brittleness of polylactide (PLA), reactive core-shell particles (RCS) with polybutadiene as core and methyl methacrylate-co-styrene-co-glycidyl methacrylate as shell were prepared to toughen PLA. Tert-dodecyl mercaptan (TDDM) was used as chain transfer agent to modify the grafting properties (such as grafting degree, shell thickness, internal and external grafting) of the core-shell particles. The introduction of TDDM decreased the grafting degree, shell thickness and the Tg of the core phase. When the content of TDDM was lower than 1.15%, the RCS particles dispersed in the PLA matrix uniformly—otherwise, agglomeration took place. The addition of RCS particles induced a higher cold crystallization temperature and a lower melting temperature of PLA which indicated the decreased crystallization ability of PLA. Dynamic mechanical analysis (DMA) results proved the good miscibility between PLA and the RCS particles and the increase of TDDM in RCS induced higher storage modulus of PLA/RCS blends. Suitable TDDM addition improved the toughening ability of RCS particles for PLA. In the present research, PLA/RCS-T4 (RCS-T4: the reactive core-shell particles with 0.76 wt % TDDM addition) blends displayed much better impact strength than other blends due to the easier cavitation/debonding ability and good dispersion morphology of the RCS-T4 particles. When the RCS-T4 content was 25 wt %, the impact strength of PLA/RCS-T4 blend reached 768 J/m, which was more than 25 times that of the pure PLA. PMID:28813019

Root Cortical Senescence Improves Growth under Suboptimal Availability of N, P, and K1[OPEN

PubMed Central

Schneider, Hannah M.

2017-01-01

Root cortical senescence (RCS) in Triticeae reduces nutrient uptake, nutrient content, respiration, and radial hydraulic conductance of root tissue. We used the functional-structural model SimRoot to evaluate the functional implications of RCS in barley (Hordeum vulgare) under suboptimal nitrate, phosphorus, and potassium availability. The utility of RCS was evaluated using sensitivity analyses in contrasting nutrient regimes. At flowering (80 d), RCS increased simulated plant growth by up to 52%, 73%, and 41% in nitrate-, phosphorus-, and potassium-limiting conditions, respectively. Plants with RCS had reduced nutrient requirement of root tissue for optimal plant growth, reduced total cumulative cortical respiration, and increased total carbon reserves. Nutrient reallocation during RCS had a greater effect on simulated plant growth than reduced respiration or nutrient uptake. Under low nutrient availability, RCS had greater benefit in plants with fewer tillers. RCS had greater benefit in phenotypes with fewer lateral roots at low nitrate availability, but the opposite was true in low phosphorus or potassium availability. Additionally, RCS was quantified in field-grown barley in different nitrogen regimes. Field and virtual soil coring simulation results demonstrated that living cortical volume per root length (an indicator of RCS) decreased with depth in younger plants, while roots of older plants had very little living cortical volume per root length. RCS may be an adaptive trait for nutrient acquisition by reallocating nutrients from senescing tissue and secondarily by reducing root respiration. These simulated results suggest that RCS merits investigation as a breeding target for enhanced soil resource acquisition and edaphic stress tolerance. PMID:28667049

Grafting Modification of the Reactive Core-Shell Particles to Enhance the Toughening Ability of Polylactide.

PubMed

Li, Zhaokun; Song, Shixin; Zhao, Xuanchen; Lv, Xue; Sun, Shulin

2017-08-16

In order to overcome the brittleness of polylactide (PLA), reactive core-shell particles (RCS) with polybutadiene as core and methyl methacrylate-co-styrene-co-glycidyl methacrylate as shell were prepared to toughen PLA. Tert-dodecyl mercaptan (TDDM) was used as chain transfer agent to modify the grafting properties (such as grafting degree, shell thickness, internal and external grafting) of the core-shell particles. The introduction of TDDM decreased the grafting degree, shell thickness and the T g of the core phase. When the content of TDDM was lower than 1.15%, the RCS particles dispersed in the PLA matrix uniformly-otherwise, agglomeration took place. The addition of RCS particles induced a higher cold crystallization temperature and a lower melting temperature of PLA which indicated the decreased crystallization ability of PLA. Dynamic mechanical analysis (DMA) results proved the good miscibility between PLA and the RCS particles and the increase of TDDM in RCS induced higher storage modulus of PLA/RCS blends. Suitable TDDM addition improved the toughening ability of RCS particles for PLA. In the present research, PLA/RCS-T4 (RCS-T4: the reactive core-shell particles with 0.76 wt % TDDM addition) blends displayed much better impact strength than other blends due to the easier cavitation/debonding ability and good dispersion morphology of the RCS-T4 particles. When the RCS-T4 content was 25 wt %, the impact strength of PLA/RCS-T4 blend reached 768 J/m, which was more than 25 times that of the pure PLA.

Replacing maize silage plus soybean meal with red clover silage plus wheat in diets for lactating dairy cows.

PubMed

Schulz, Franziska; Westreicher-Kristen, Edwin; Knappstein, Karin; Molkentin, Joachim; Susenbeth, Andreas

2018-02-01

The objectives of this study were to evaluate the effects of replacing maize silage plus soybean meal with red clover silage (RCS) plus wheat on feed intake, diet digestibility, N partitioning, urinary excretion of purine derivatives, and milk production in dairy cows. Forty-four lactating German Holstein cows were used in a 4 × 4 Latin square design with 21-d periods composed of a 13-d adaptation phase followed by an 8-d sampling phase. Experimental diets offered as total mixed ration consisted of a constant forage-to-concentrate ratio (75:25) with targeted proportions of RCS-to-maize silage of 15:60 (RCS 15 ), 30:45 (RCS 30 ), 45:30 (RCS 45 ), and 60:15 (RCS 60 ) on a dry matter (DM) basis. Increasing the proportion of RCS plus wheat in the diet decreased linearly the intake of DM from 22.4 to 19.8 kg/d, and of organic matter from 21.1 to 18.1 kg/d. The apparent total tract digestibility (ATTD) of DM and organic matter did not differ across diets and averaged 68.4 and 70.5%, respectively. However, ATTD of N decreased linearly from 68.5 to 63.2%, whereas ATTD of neutral detergent fiber and acid detergent fiber increased linearly from 50.4 to 59.6% and from 48.4 to 57.7%, respectively, when increasing the proportion of RCS plus wheat. Fecal N excretion increased from 31.6 (RCS 15 ) to 37.2% (RCS 60 ) of N intake, whereas urinary N excretion was the lowest (32.8% of N intake) with RCS 45 . Hence, N efficiency (milk N/N intake) decreased linearly with incremental levels of RCS plus wheat, being the lowest when feeding RCS 60 (25.4%), probably due to increased nonprotein N proportion in total dietary N. Urinary excretion of purine derivatives decreased linearly from 378 to 339 mmol/d, which suggests that increasing levels of RCS plus wheat reduced the microbial crude protein flow at the duodenum. Milk yield and milk protein concentration declined linearly from 35.9 to 30.2 kg/d and from 3.20 to 3.01%, respectively, when increasing the proportion of RCS plus wheat. In conclusion, caution should be taken before introducing high levels of RCS plus wheat in diets of high-yielding dairy cows. However, RCS plus wheat can be included up to 30% of the dairy cow diet (DM basis) without a reduction in lactation performance. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Heat or cold priming-induced cross-tolerance to abiotic stresses in plants: key regulators and possible mechanisms.

PubMed

Hossain, Mohammad Anwar; Li, Zhong-Guang; Hoque, Tahsina Sharmin; Burritt, David J; Fujita, Masayuki; Munné-Bosch, Sergi

2018-01-01

Plants growing under field conditions are constantly exposed, either simultaneously or sequentially, to more than one abiotic stress factor. Plants have evolved sophisticated sensory systems to perceive a number of stress signals that allow them to activate the most adequate response to grow and survive in a given environment. Recently, cross-stress tolerance (i.e. tolerance to a second, strong stress after a different type of mild primary stress) has gained attention as a potential means of producing stress-resistant crops to aid with global food security. Heat or cold priming-induced cross-tolerance is very common in plants and often results from the synergistic co-activation of multiple stress signalling pathways, which involve reactive nitrogen species (RNS), reactive oxygen species (ROS), reactive carbonyl species (RCS), plant hormones and transcription factors. Recent studies have shown that the signalling functions of ROS, RNS and RCS, most particularly hydrogen peroxide, nitric oxide (NO) and methylglyoxal (MG), provide resistance to abiotic stresses and underpin cross-stress tolerance in plants by modulating the expression of genes as well as the post-translational modification of proteins. The current review highlights the key regulators and mechanisms underlying heat or cold priming-induced cross-stress tolerance in plants, with a focus on ROS, MG and NO signalling, as well as on the role of antioxidant and glyoxalase systems, osmolytes, heat-shock proteins (HSPs) and hormones. Our aim is also to provide a comprehensive idea on the topic for researchers using heat or cold priming-induced cross-tolerance as a mechanism to improve crop yields under multiple abiotic stresses.

Alterations in NMDA receptor expression during retinal degeneration in the RCS rat.

PubMed

Gründer, T; Kohler, K; Guenther, E

2001-01-01

To determine how a progressive loss of photoreceptor cells and the concomitant loss of glutamatergic input to second-order neurons can affect inner-retinal signaling, glutamate receptor expression was analyzed in the Royal College of Surgeons (RCS) rat, an animal model of retinitis pigmentosa. Immunohistochemistry was performed on retinal sections of RCS rats and congenic controls between postnatal (P) day 3 and the aged adult (up to P350) using specific antibodies against N-methyl-D-aspartate (NMDA) subunits. All NMDA subunits (NR1, NR2A-2D) were expressed in control and dystrophic retinas at all ages, and distinct patterns of labeling were found in horizontal cells, subpopulations of amacrine cells and ganglion cells, as well as in the outer and inner plexiform layer (IPL). NRI immunoreactivity in the inner plexiform layer of adult control retinas was concentrated in two distinct bands, indicating a synaptic localization of NMDA receptors in the OFF and ON signal pathways. In the RCS retina, these bands of NRI immunoreactivity in the IPL were much weaker in animals older than P40. In parallel, NR2B immunoreactivity in the outer plexiform layer (OPL) of RCS rats was always reduced compared to controls and vanished between P40 and P120. The most striking alteration observed in the degenerating retina, however, was a strong expression of NRI immunoreactivity in Müller cell processes in the inner retina which was not observed in control animals and which was present prior to any visible sign of photoreceptor degeneration. The results suggest functional changes in glutamatergic receptor signaling in the dystrophic retina and a possible involvement of Müller cells in early processes of this disease.

Metabolism of RCS-8, a synthetic cannabinoid with cyclohexyl structure, in human hepatocytes by high-resolution MS

PubMed Central

Wohlfarth, Ariane; Pang, Shaokun; Zhu, Mingshe; Gandhi, Adarsh S; Scheidweiler, Karl B; Huestis, Marilyn A

2015-01-01

Background Since 2008, synthetic cannabinoids are major new designer drugs of abuse. They are extensively metabolized and excreted in urine, but limited human metabolism data are available. As there are no reports on the metabolism of RCS-8, a scheduled phenylacetylindole synthetic cannabinoid with an N-cyclohexylethyl moiety, we investigated metabolism of this new designer drug by human hepatocytes and high resolution MS. Methods After human hepatocyte incubation with RCS-8, samples were analyzed on a TripleTOF 5600+ mass spectrometer with time-of-flight survey scan and information-dependent acquisition triggered product ion scans. Data mining of the accurate mass full scan and product ion spectra employed different data processing algorithms. Results and Conclusion More than 20 RCS-8 metabolites were identified, products of oxidation, demethylation, and glucuronidation. Major metabolites and targets for analytical methods were hydroxyphenyl RCS - 8 glucuronide, a variety of hydroxycyclohexyl-hydroxyphenyl RCS-8 glucuronides, hydroxyphenyl RCS-8, as well as the demethyl-hydroxycyclohexyl RCS-8 glucuronide. PMID:24946920

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ponomarenko, N. S.; Poluektov, O. G.; Bylina, E. J.

High-field electron paramagnetic resonance (HF EPR) has been employed to investigate the primary electron donor electronic structure of Blastochloris viridis heterodimer mutant reaction centers (RCs). In these mutants the amino acid substitution His(M200)Leu or His(L173)Leu eliminates a ligand to the primary electron donor, resulting in the loss of a magnesium in one of the constituent bacteriochlorophylls (BChl). Thus, the native BChl/BChl homodimer primary donor is converted into a BChl/bacteriopheophytin (BPhe) heterodimer. The heterodimer primary donor radical in chemically oxidized RCs exhibits a broadened EPR line indicating a highly asymmetric distribution of the unpaired electron over both dimer constituents. Observed tripletmore » state EPR signals confirm localization of the excitation on the BChl half of the heterodimer primary donor. Theoretical simulation of the triplet EPR lineshapes clearly shows that, in the case of mutants, triplet states are formed by an intersystem crossing mechanism in contrast to the radical pair mechanism in wild type RCs. Photooxidation of the mutant RCs results in formation of a BPhe anion radical within the heterodimer pair. The accumulation of an intradimer BPhe anion is caused by the substantial loss of interaction between constituents of the heterodimer primary donor along with an increase in the reduction potential of the heterodimer primary donor D/D{sup +} couple. This allows oxidation of the cytochrome even at cryogenic temperatures and reduction of each constituent of the heterodimer primary donor individually. Despite a low yield of primary donor radicals, the enhancement of the semiquinone-iron pair EPR signals in these mutants indicates the presence of kinetically viable electron donors.« less

The Rcs regulon in Proteus mirabilis: implications for motility, biofilm formation, and virulence.

PubMed

Howery, Kristen E; Clemmer, Katy M; Rather, Philip N

2016-11-01

The overall role of the Rcs phosphorelay in Proteus mirabilis is largely unknown. Previous work had demonstrated that the Rcs phosphorelay represses the flhDC operon and activates the minCDE cell division inhibition system. To identify additional cellular functions regulated by the Rcs phosphorelay, an analysis of RNA-seq data was undertaken. In this report, the results of the RNA-sequencing are discussed with an emphasis on the predicted roles of the Rcs phosphorelay in swarmer cell differentiation, motility, biofilm formation, and virulence. RcsB is shown to activate genes important for differentiation and fimbriae formation, while repressing the expression of genes important for motility and virulence. Additionally, to follow up on the RNA-Seq data, we demonstrate that an rcsB mutant is deficient in its ability to form biofilm and exhibits enhanced virulence in a Galleria mellonella waxworm model. Overall, these results indicate the Rcs regulon in P. mirabilis extends beyond flagellar genes to include those involved in biofilm formation and virulence. Furthermore, the information presented in this study may provide clues to additional roles of the Rcs phosphorelay in other members of the Enterobacteriaceae.

Conformational dynamism for DNA interaction in the Salmonella RcsB response regulator

PubMed Central

Miguel-Romero, Laura; Huesa, Juanjo; García, Pablo; García-del Portillo, Francisco

2018-01-01

Abstract The RcsCDB phosphorelay system controls an extremely large regulon in Enterobacteriaceae that involves processes such as biofilm formation, flagella production, synthesis of extracellular capsules and cell division. Therefore, fine-tuning of this system is essential for virulence in pathogenic microorganisms of this group. The final master effector of the RcsCDB system is the response regulator (RR) RcsB, which activates or represses multiple genes by binding to different promoter regions. This regulatory activity of RcsB can be done alone or in combination with additional transcriptional factors in phosphorylated or dephosphorylated states. The capacity of RcsB to interact with multiple promoters and partners, either dephosphorylated or phosphorylated, suggests an extremely conformational dynamism for this RR. To shed light on the activation mechanism of RcsB and its implication on promoter recognition, we solved the crystal structure of full-length RcsB from Salmonella enterica serovar Typhimurium in the presence and absence of a phosphomimetic molecule BeF3−. These two novel structures have guided an extensive site-directed mutagenesis study at the structural and functional level that confirms RcsB conformational plasticity and dynamism. Our data allowed us to propose a β5-T switch mechanism where phosphorylation is coupled to alternative DNA binding ways and which highlights the conformational dynamism of RcsB to be so pleiotropic. PMID:29186528

Comprehensive analysis of the lipophilic reactive carbonyls present in biological specimens by LC/ESI-MS/MS.

PubMed

Tomono, Susumu; Miyoshi, Noriyuki; Ohshima, Hiroshi

2015-04-15

A new analytical method has been developed for profiling lipophilic reactive carbonyls (RCs) such as aldehydes and ketones in biological samples using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) with selected reaction monitoring (SRM). The method consists of several phases, including (1) extraction of lipophilic RCs with a chloroform/methanol mixture; (2) derivatization of the extracted RCs with dansyl hydrazine (DH); and (3) SRM detection of the characteristic product ion of the 5-dimethylaminonaphthalene-1-sulfonyl moiety (m/z 236.1). The analytical results were expressed as RC maps, which allowed for the occurrence and levels of different lipophilic RCs to be visualized. We also developed a highly reproducible and accurate method to extract, purify and derivatize RCs in small volumes of biological specimens. This method was applied to the detection of free RCs in mice plasma samples, and resulted in the detection of more than 400 RCs in samples obtained from C57BL/6J mice. Thirty-four of these RCs were identified by comparison with authentic RCs. This method could be used to investigate the levels of RCs in biological and environmental samples, as well as studying the role of lipid peroxidation in oxidative stress related-disorders and discovering new biomarkers for the early diagnosis of these diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

Visualization of Flowfield Modification by RCS Jets on a Capsule Entry Vehicle

NASA Technical Reports Server (NTRS)

Danehy, P. M.; Inman, J. A.; Alderfer, D. W.; Buck, G. M.; Schwartz, R.

2008-01-01

Nitric oxide planar laser-induced fluorescence (NO PLIF) has been used to visualize the flow on the aft-body of an entry capsule having an activated RCS jet in NASA Langley Research Center's 31-Inch Mach 10 wind tunnel facility. A capsule shape representative of the Apollo command module was tested. These tests were performed to demonstrate the ability of the PLIF method to visualize RCS jet flow while providing some preliminary input to NASA's Orion Vehicle design team. Two different RCS nozzle designs - conical and contoured - were tested. The conical and contoured nozzles had area ratios of 13.4 and 22.5 respectively. The conical nozzle had a half-angle of 10 . Low- and high-Reynolds number cases were investigated by changing the tunnel stagnation pressure from 350 psi to 1300 psi, resulting in freestream Reynolds numbers of 0.56 and 1.8 million per foot respectively. For both of these cases, three different jet plenum pressures were tested (nominally 56, 250 and 500 psi). A single angle-of-attack was investigated (24 degrees). NO PLIF uses an ultraviolet laser sheet to interrogate a slice in the flow containing seeded NO; this UV light excites fluorescence from the NO molecules which is detected by a high-speed digital camera. The system has spatial resolution of about 200 microns (2 pixel blurring) and has flow-stopping time resolution (approximately 1 microsecond). NO was seeded into the flow two different ways. First, the RCS jet fluid was seeded with approximately 1-5% NO, with the balance N2. This allowed observation of the shape, structure and trajectory of the RCS jets. Visualizations of both laminar and turbulent flow jet features were obtained. Visualizations were obtained with the tunnel operating at Mach 10 and also with the test section held at a constant pressure similar to the aftbody static pressure (0.04 psi) obtained during tunnel runs. These two conditions are called "tunnel on" and "tunnel off" respectively. Second, the forebody flow was seeded with a very low flowrate (<100 standard cubic centimeters per minute) of pure NO. This trace gas was entrained into and allowed visualization of the shear layer forming between the expansion fan on the shoulder of the model and the recirculating separated flow in the wake of the model. This shear layer was observed to be laminar in the absence of the RCS jet operation and turbulent above a certain RCS jet flowrate. Furthermore, the operation of the RCS jet is seen to push the shear layer out away from the model, with a higher jet pressures resulting in larger deflections. Figures show some data from this test, partially processed. In the final paper, these images will be processed and rendered on a three dimensional visualization of the test hardware for clearer visualization and interpretation of the flowfields.

Final Report of the Haystack Orbital Debris Data Review Panel

NASA Technical Reports Server (NTRS)

Barton, David K.; Brillinger, David; McDaniel, Patrick; Pollock, Kenneth H.; El-Shaarawi, A. H.; Tuley, Michael T.

1998-01-01

The Haystack Orbital Debris Data Review Panel was established in December 1996 to consider the adequacy of the data on orbital debris gathered over the past several years with the Haystack radar, and the accuracy of the methods used to estimate the flux vs. size relationship for this debris. The four specific issues addressed for the Panel were: 1. The number of observations relative to the estimated population of interest 2. The inherent ambiguity between the measured radar cross section (RCS) and the inferred physical size of the object 3. The inherent aspect angle limitation in viewing each object and its relationship to object geometry 4. The adequacy of the sample data set to characterize the debris population's potential geometry. Further discussion and interpretation of these issues, and identification of the detailed questions contributing to them, are discussed in this report.

The RclR Protein Is a Reactive Chlorine-specific Transcription Factor in Escherichia coli *

PubMed Central

Parker, Benjamin W.; Schwessinger, Emily A.; Jakob, Ursula; Gray, Michael J.

2013-01-01

Reactive chlorine species (RCS) such as hypochlorous acid are powerful antimicrobial oxidants. Used extensively for disinfection in household and industrial settings (i.e. as bleach), RCS are also naturally generated in high quantities during the innate immune response. Bacterial responses to RCS are complex and differ substantially from the well characterized responses to other physiologically relevant oxidants, like peroxide or superoxide. Several RCS-sensitive transcription factors have been identified in bacteria, but most of them respond to multiple stressors whose damaging effects overlap with those of RCS, including reactive oxygen species and electrophiles. We have now used in vivo genetic and in vitro biochemical methods to identify and demonstrate that Escherichia coli RclR (formerly YkgD) is a redox-regulated transcriptional activator of the AraC family, whose highly conserved cysteine residues are specifically sensitive to oxidation by RCS. Oxidation of these cysteines leads to strong, highly specific activation of expression of genes required for survival of RCS stress. These results demonstrate the existence of a widely conserved bacterial regulon devoted specifically to RCS resistance. PMID:24078635

The RclR protein is a reactive chlorine-specific transcription factor in Escherichia coli.

PubMed

Parker, Benjamin W; Schwessinger, Emily A; Jakob, Ursula; Gray, Michael J

2013-11-08

Reactive chlorine species (RCS) such as hypochlorous acid are powerful antimicrobial oxidants. Used extensively for disinfection in household and industrial settings (i.e. as bleach), RCS are also naturally generated in high quantities during the innate immune response. Bacterial responses to RCS are complex and differ substantially from the well characterized responses to other physiologically relevant oxidants, like peroxide or superoxide. Several RCS-sensitive transcription factors have been identified in bacteria, but most of them respond to multiple stressors whose damaging effects overlap with those of RCS, including reactive oxygen species and electrophiles. We have now used in vivo genetic and in vitro biochemical methods to identify and demonstrate that Escherichia coli RclR (formerly YkgD) is a redox-regulated transcriptional activator of the AraC family, whose highly conserved cysteine residues are specifically sensitive to oxidation by RCS. Oxidation of these cysteines leads to strong, highly specific activation of expression of genes required for survival of RCS stress. These results demonstrate the existence of a widely conserved bacterial regulon devoted specifically to RCS resistance.

Conformational dynamism for DNA interaction in the Salmonella RcsB response regulator.

PubMed

Casino, Patricia; Miguel-Romero, Laura; Huesa, Juanjo; García, Pablo; García-Del Portillo, Francisco; Marina, Alberto

2018-01-09

The RcsCDB phosphorelay system controls an extremely large regulon in Enterobacteriaceae that involves processes such as biofilm formation, flagella production, synthesis of extracellular capsules and cell division. Therefore, fine-tuning of this system is essential for virulence in pathogenic microorganisms of this group. The final master effector of the RcsCDB system is the response regulator (RR) RcsB, which activates or represses multiple genes by binding to different promoter regions. This regulatory activity of RcsB can be done alone or in combination with additional transcriptional factors in phosphorylated or dephosphorylated states. The capacity of RcsB to interact with multiple promoters and partners, either dephosphorylated or phosphorylated, suggests an extremely conformational dynamism for this RR. To shed light on the activation mechanism of RcsB and its implication on promoter recognition, we solved the crystal structure of full-length RcsB from Salmonella enterica serovar Typhimurium in the presence and absence of a phosphomimetic molecule BeF3-. These two novel structures have guided an extensive site-directed mutagenesis study at the structural and functional level that confirms RcsB conformational plasticity and dynamism. Our data allowed us to propose a β5-T switch mechanism where phosphorylation is coupled to alternative DNA binding ways and which highlights the conformational dynamism of RcsB to be so pleiotropic. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

A fast RCS accuracy assessment method for passive radar calibrators

NASA Astrophysics Data System (ADS)

Zhou, Yongsheng; Li, Chuanrong; Tang, Lingli; Ma, Lingling; Liu, QI

2016-10-01

In microwave radar radiometric calibration, the corner reflector acts as the standard reference target but its structure is usually deformed during the transportation and installation, or deformed by wind and gravity while permanently installed outdoor, which will decrease the RCS accuracy and therefore the radiometric calibration accuracy. A fast RCS accuracy measurement method based on 3-D measuring instrument and RCS simulation was proposed in this paper for tracking the characteristic variation of the corner reflector. In the first step, RCS simulation algorithm was selected and its simulation accuracy was assessed. In the second step, the 3-D measuring instrument was selected and its measuring accuracy was evaluated. Once the accuracy of the selected RCS simulation algorithm and 3-D measuring instrument was satisfied for the RCS accuracy assessment, the 3-D structure of the corner reflector would be obtained by the 3-D measuring instrument, and then the RCSs of the obtained 3-D structure and corresponding ideal structure would be calculated respectively based on the selected RCS simulation algorithm. The final RCS accuracy was the absolute difference of the two RCS calculation results. The advantage of the proposed method was that it could be applied outdoor easily, avoiding the correlation among the plate edge length error, plate orthogonality error, plate curvature error. The accuracy of this method is higher than the method using distortion equation. In the end of the paper, a measurement example was presented in order to show the performance of the proposed method.

Healthcare tariffs for specialist inpatient neurorehabilitation services: rationale and development of a UK casemix and costing methodology.

PubMed

Turner-Stokes, Lynne; Sutch, Stephen; Dredge, Robert

2012-03-01

To describe the rationale and development of a casemix model and costing methodology for tariff development for specialist neurorehabilitation services in the UK. Patients with complex needs incur higher treatment costs. Fair payment should be weighted in proportion to costs of providing treatment, and should allow for variation over time CASEMIX MODEL AND BAND-WEIGHTING: Case complexity is measured by the Rehabilitation Complexity Scale (RCS). Cases are divided into five bands of complexity, based on the total RCS score. The principal determinant of costs in rehabilitation is staff time. Total staff hours/week (estimated from the Northwick Park Nursing and Therapy Dependency Scales) are analysed within each complexity band, through cross-sectional analysis of parallel ratings. A 'band-weighting' factor is derived from the relative proportions of staff time within each of the five bands. Total unit treatment costs are obtained from retrospective analysis of provider hospitals' budget and accounting statements. Mean bed-day costs (total unit cost/occupied bed days) are divided broadly into 'variable' and 'non-variable' components. In the weighted costing model, the band-weighting factor is applied to the variable portion of the bed-day cost to derive a banded cost, and thence a set of cost-multipliers. Preliminary data from one unit are presented to illustrate how this weighted costing model will be applied to derive a multilevel banded payment model, based on serial complexity ratings, to allow for change over time.

Assessing the performance of a covert automatic target recognition algorithm

NASA Astrophysics Data System (ADS)

Ehrman, Lisa M.; Lanterman, Aaron D.

2005-05-01

Passive radar systems exploit illuminators of opportunity, such as TV and FM radio, to illuminate potential targets. Doing so allows them to operate covertly and inexpensively. Our research seeks to enhance passive radar systems by adding automatic target recognition (ATR) capabilities. In previous papers we proposed conducting ATR by comparing the radar cross section (RCS) of aircraft detected by a passive radar system to the precomputed RCS of aircraft in the target class. To effectively model the low-frequency setting, the comparison is made via a Rician likelihood model. Monte Carlo simulations indicate that the approach is viable. This paper builds on that work by developing a method for quickly assessing the potential performance of the ATR algorithm without using exhaustive Monte Carlo trials. This method exploits the relation between the probability of error in a binary hypothesis test under the Bayesian framework to the Chernoff information. Since the data are well-modeled as Rician, we begin by deriving a closed-form approximation for the Chernoff information between two Rician densities. This leads to an approximation for the probability of error in the classification algorithm that is a function of the number of available measurements. We conclude with an application that would be particularly cumbersome to accomplish via Monte Carlo trials, but that can be quickly addressed using the Chernoff information approach. This application evaluates the length of time that an aircraft must be tracked before the probability of error in the ATR algorithm drops below a desired threshold.

The Influence of Contextual Contrast on Syntactic Processing: Evidence for Strong-Interaction in Sentence Comprehension

ERIC Educational Resources Information Center

Grodner, D.; Gibson, E.; Watson, D.

2005-01-01

The present study compares the processing of unambiguous restrictive and non-restrictive relative clauses (RCs) within both a null context and a supportive discourse using a self-paced reading methodology. Individuals read restrictive RCs more slowly than non-restrictive RCs in a null context, but processed restrictive RCs faster than…

Determination of YAV-8B Reaction Control System bleed flow usage

NASA Technical Reports Server (NTRS)

Borchers, Paul F.; Moralez, Ernesto, III; Merrick, Vernon K.; Stortz, Michael W.; Eames, David J. H.

1992-01-01

Using a calibrated Rolls-Royce Pegasus engine, total Reaction Control System (RCS) bleed flow rates have been measured on a YAV-8B Harrier during typical short takeoff, transition, hover and vertical landing maneuvers. Using existing aircraft instrumentation and pressure taps located in the RCS ducts, bleed flow rates at each RCS valve were also measured directly during flight and ground tests. These data were compared with the calibrated engine data and with the RCS part of a YAV-8B mathematical model used in piloted simulation at NASA Ames Research Center. Areas of disagreement were small, being confined to the estimation of closed RCS valve leakages and the modeling of the RCS butterfly valve pressure losses.

Histomicrobiologic aspects of the root canal system and periapical lesions in dogs' teeth after rotary instrumentation and intracanal dressing with Ca(OH)2 pastes.

PubMed

Soares, Janir Alves; Leonardo, Mário Roberto; da Silva, Léa Assed Bezerra; Tanomaru Filho, Mário; Ito, Izabel Yoko

2006-10-01

The purpose of this study was to evaluate the distribution of microorganisms in the root canal system (RCS) and periapical lesions of dogs' teeth after rotary instrumentation and placement of different calcium hydroxide [Ca(OH)2]-based intracanal dressings. Chronic periapical lesions were experimentally induced in 80 premolar roots of four dogs. Instrumentation was undertaken using the ProFile rotary system and irrigation with 5.25% sodium hypochlorite. The following Ca(OH)2-based pastes were applied for 21 days: group 1 - Calen (n=18); group 2 - Calen+CPMC (n=20); group 3 - Ca(OH)2 p.a. + anaesthetic solution (n=16) and group 4 - Ca(OH)2 p.a.+ 2% chlorhexidine digluconate (n=18). Eight root canals without endodontic treatment constituted the control group. Histological sections were obtained and stained with Brown & Brenn staining technique to evaluate the presence of microorganisms in the main root canal, ramifications of the apical delta and secondary canals, apical cementoplasts, dentinal tubules, areas of cemental resorption and periapical lesions. The results were analyzed statistically by the Mann-Whitney U test (p<0.05). The control group showed the highest prevalence of microorganisms in all sites evaluated. Gram-positive cocci, bacilli and filaments were the most frequent morphotypes. Similar microbial distribution patterns in the RCS and areas of cementum resorption were observed in all groups (p>0.05). The percentage of RCS sites containing microorganisms in groups 1, 2, 3, 4 and control were: 67.6%, 62.5%, 78.2%, 62.0% and 87.6%, respectively. In conclusion, the histomicrobiological analysis showed that the rotary instrumentation and the different calcium hydroxide pastes employed did not effectively eliminate the infection from the RCS and periapical lesions. However, several bacteria seen in the histological sections were probably dead or were inactivated by the biomechanical preparation and calcium hydroxide-based intracanal dressing.

Drosophila E-cadherin is required for the maintenance of ring canals anchoring to mechanically withstand tissue growth.

PubMed

Loyer, Nicolas; Kolotuev, Irina; Pinot, Mathieu; Le Borgne, Roland

2015-10-13

Intercellular bridges called "ring canals" (RCs) resulting from incomplete cytokinesis play an essential role in intercellular communication in somatic and germinal tissues. During Drosophila oogenesis, RCs connect the maturing oocyte to nurse cells supporting its growth. Despite numerous genetic screens aimed at identifying genes involved in RC biogenesis and maturation, how RCs anchor to the plasma membrane (PM) throughout development remains unexplained. In this study, we report that the clathrin adaptor protein 1 (AP-1) complex, although dispensable for the biogenesis of RCs, is required for the maintenance of the anchorage of RCs to the PM to withstand the increased membrane tension associated with the exponential tissue growth at the onset of vitellogenesis. Here we unravel the mechanisms by which AP-1 enables the maintenance of RCs' anchoring to the PM during size expansion. We show that AP-1 regulates the localization of the intercellular adhesion molecule E-cadherin and that loss of AP-1 causes the disappearance of the E-cadherin-containing adhesive clusters surrounding the RCs. E-cadherin itself is shown to be required for the maintenance of the RCs' anchorage, a function previously unrecognized because of functional compensation by N-cadherin. Scanning block-face EM combined with transmission EM analyses reveals the presence of interdigitated, actin- and Moesin-positive, microvilli-like structures wrapping the RCs. Thus, by modulating E-cadherin trafficking, we show that the sustained E-cadherin-dependent adhesion organizes the microvilli meshwork and ensures the proper attachment of RCs to the PM, thereby counteracting the increasing membrane tension induced by exponential tissue growth.

Neurotransmitter contents in the retina of RCS rat.

PubMed

Okada, M; Okuma, Y; Osumi, Y; Nishihara, M; Yokotani, K; Ueno, H

2000-12-01

Retinitis pigmentosa is a hereditary disease characterized by gradually developing degeneration of photoreceptors. The Royal College of Surgeons (RCS) rat is an experimental model of retinitis pigmentosa. However, there is a paucity of information concerning neurotransmitter contents in the retina of RCS rats. Thus, we determined the retinal contents of neurotransmitters in RCS rats at 4 and 23 weeks postnatally and in age-matched congenic control rats. Dopamine (DA) and acetylcholine (ACh) were electrochemically measured by high-performance liquid chromatography (HPLC). Neuroactive amino acids, including gamma-aminobutyric acid (GABA) and taurine, were determined by means of an HPLC-precolumn derivatization method. Contents of DA, ACh, glutamate, aspartate and GABA in the retina of RCS rats 4 weeks postnatally were within normal ranges. At 23 weeks, the retinal contents of DA, glutamate and aspartate in the RCS rats were significantly lower than in the age-matched control rats, while the contents of ACh and GABA were unaffected even at this later stage. On the other hand, the retinal content of glycine in the RCS rats at 23 weeks was significantly higher than that in the age-matched control rats. It is interesting to note that the content of taurine in the RCS rats had already decreased at 4 weeks postnatally and the decrease was more marked at 23 weeks. The decrease in taurine content is probably the first sign of degeneration revealed by the retinal neurotransmitters of RCS rats.

Regulator of calmodulin signaling (RCS) knockout mice display anxiety-like behavior and motivational deficits

PubMed Central

Davis, Maya M.; Olausson, Peter; Greengard, Paul; Taylor, Jane R.; Nairn, Angus C.

2013-01-01

Regulator of calmodulin (CaM) signaling (RCS), when phosphorylated by protein kinase A (PKA) on Ser55, binds to CaM and inhibits CaM-dependent signaling. RCS expression is high in the dorsal striatum, nucleus accumbens and amygdala, suggesting that the protein is involved in limbic-striatal function. To test this hypothesis, we examined RCS knockout (KO) mice in behavioral models dependent on these brain areas. Mice were tested for food-reinforced instrumental conditioning and responding under a progressive ratio (PR) schedule of reinforcement and in models of anxiety (elevated plus maze and open field). While RCS KO mice showed normal acquisition of a food-motivated instrumental response, they exhibited a lower breakpoint value when tested on responding under a PR schedule of reinforcement. RCS KO mice also displayed decreased exploration in both the open arms of an elevated plus maze and in the center region of an open field, suggesting an enhanced anxiety response. Biochemical studies revealed a reduction in the levels of dopamine and cAMP-regulated phosphoprotein (DARPP-32) in the striatum of RCS KO mice. DARPP-32 is important in reward-mediated behavior, suggestive of a possible role for DARPP-32 in mediating some of the effects of RCS. Together these results implicate a novel PKA-regulated phosphoprotein, RCS, in the etiology of motivational deficits and anxiety. PMID:22250817

Wide-Angle Multistatic Synthetic Aperture Radar: Focused Image Formation and Aliasing Artifact Mitigation

DTIC Science & Technology

2005-07-01

Progress in Applied Computational Electro- magnetics. ACES, Syracuse, NY, 2004. 91. Mahafza, Bassem R. Radar Systems Analysis and Design Using MATLAB...Figure Page 4.5. RCS chamber coordinate system . . . . . . . . . . . . . . . . . 88 4.6. AFIT’s RCS Chamber...4.11. Frequency domain schematic of RCS data collection . . . . . . 98 4.12. Spherical coordinate system for RCS data calibration . . . . . . 102 4.13

Trends in exposure to respirable crystalline silica (1986-2014) in Australian mining.

PubMed

Peters, Susan; Vermeulen, Roel; Fritschi, Lin; Musk, Aw Bill; Reid, Alison; de Klerk, Nicholas

2017-08-01

Respirable crystalline silica (RCS) has been associated with severe health risks. Exposures in Western Australia (WA) have been typically high in hard-rock mining and have reduced substantially since the mid-1900s. We described trends in RCS exposure in WA miners over the past 30 years. A total of 79 445 reported personal RCS exposure measurements, covering the years 1986-2014, were examined. Mixed-effects models were applied to estimate RCS exposure levels, including spline terms to estimate a time trend. An overall downward trend of about -8% per year was observed for RCS exposures in WA mining. Highest RCS exposure levels were modeled for base metal mining and exploration settings. Drilling occupations were among the highest exposed jobs. RCS exposure levels have fallen considerably in the last three decades. However, there are still mining occupations that may need further attention to avoid adverse health effects in these workers. © 2017 Wiley Periodicals, Inc.

The Rcs-Regulated Colanic Acid Capsule Maintains Membrane Potential in Salmonella enterica serovar Typhimurium

PubMed Central

Pando, Jasmine M.; Karlinsey, Joyce E.; Lara, Jimmie C.; Libby, Stephen J.

2017-01-01

ABSTRACT The Rcs phosphorelay and Psp (phage shock protein) systems are envelope stress responses that are highly conserved in gammaproteobacteria. The Rcs regulon was found to be strongly induced during metal deprivation of Salmonella enterica serovar Typhimurium lacking the Psp response. Nineteen genes activated by the RcsA-RcsB response regulator make up an operon responsible for the production of colanic acid capsular polysaccharide, which promotes biofilm development. Despite more than half a century of research, the physiological function of colanic acid has remained elusive. Here we show that Rcs-dependent colanic acid production maintains the transmembrane electrical potential and proton motive force in cooperation with the Psp response. Production of negatively charged exopolysaccharide covalently bound to the outer membrane may enhance the surface potential by increasing the local proton concentration. This provides a unifying mechanism to account for diverse Rcs/colanic acid-related phenotypes, including susceptibility to membrane-damaging agents and biofilm formation. PMID:28588134

ADST, Version Description Document for the BDS-D M1 1.0.0

DTIC Science & Technology

1992-12-22

1.1 date: 1992/10/01 23:32:59; author: crn-adst; state: Exp; Initial Version RCS file: ./common/include/cig- f /RCS/if...eh~eff.h,v Working file: if...libsrc/libfifo/RCS/ f -enqueue.c,v working file: f_enqueue.c head: 1.1 description: ITO - 6.6.1 baseline revision 1.1 date: 1992/10/01 23:43:13; author...crn-adst; state: Exp; Initial Version RCS file: ./common/libsrc/libfifo/RCS/ f -init.c,v working file: f -init.c head: 1.1 description: ITO - 6.6.1

Study of wave form compensation at CSNS/RCS magnets

NASA Astrophysics Data System (ADS)

Xu, S. Y.; Fu, S. N.; Wang, S.; Kang, W.; Qi, X.; Li, L.; Deng, C. D.; Zhou, J. X.

2018-07-01

A method of wave form compensation for magnets of the Rapid Cycling Synchrotron (RCS), which is based on transfer function between magnetic field and exciting current, was investigated on the magnets of RCS of Chinese Spallation Neutron Source (CSNS). By performing wave form compensation, the magnetic field ramping function for RCS magnets can be accurately controlled to the given wave form, which is not limited to sine function. The method of wave form compensation introduced in this paper can be used to reduce the magnetic field tracking errors, and can also be used to accurately control the betatron tune for RCS.

Gene expression changes in the retina following subretinal injection of human neural progenitor cells into a rodent model for retinal degeneration.

PubMed

Jones, Melissa K; Lu, Bin; Saghizadeh, Mehrnoosh; Wang, Shaomei

2016-01-01

Retinal degenerative diseases (RDDs) affect millions of people and are the leading cause of vision loss. Although treatment options for RDDs are limited, stem and progenitor cell-based therapies have great potential to halt or slow the progression of vision loss. Our previous studies have shown that a single subretinal injection of human forebrain derived neural progenitor cells (hNPCs) into the Royal College of Surgeons (RCS) retinal degenerate rat offers long-term preservation of photoreceptors and visual function. Furthermore, neural progenitor cells are currently in clinical trials for treating age-related macular degeneration; however, the molecular mechanisms of stem cell-based therapies are largely unknown. This is the first study to analyze gene expression changes in the retina of RCS rats following subretinal injection of hNPCs using high-throughput sequencing. RNA-seq data of retinas from RCS rats injected with hNPCs (RCS(hNPCs)) were compared to sham surgery in RCS (RCS(sham)) and wild-type Long Evans (LE(sham)) rats. Differential gene expression patterns were determined with in silico analysis and confirmed with qRT-PCR. Function, biologic, cellular component, and pathway analyses were performed on differentially expressed genes and investigated with immunofluorescent staining experiments. Analysis of the gene expression data sets identified 1,215 genes that were differentially expressed between RCS(sham) and LE(sham) samples. Additionally, 283 genes were differentially expressed between the RCS(hNPCs) and RCS(sham) samples. Comparison of these two gene sets identified 68 genes with inverse expression (termed rescue genes), including Pdc, Rp1, and Cdc42ep5. Functional, biologic, and cellular component analyses indicate that the immune response is enhanced in RCS(sham). Pathway analysis of the differential expression gene sets identified three affected pathways in RCS(hNPCs), which all play roles in phagocytosis signaling. Immunofluorescent staining detected the increased presence of macrophages and microglia in RCS(sham) retinas, which decreased in RCS(hNPCs) retinas similar to the patterns detected in LE(sham). The results from this study provide evidence of the gene expression changes that occur following treatment with hNPCs in the degenerating retina. This information can be used in future studies to potentially enhance or predict responses to hNPC and other stem cell therapies for retinal degenerative diseases.

Regulation of the Min Cell Division Inhibition Complex by the Rcs Phosphorelay in Proteus mirabilis.

PubMed

Howery, Kristen E; Clemmer, Katy M; Şimşek, Emrah; Kim, Minsu; Rather, Philip N

2015-08-01

A key regulator of swarming in Proteus mirabilis is the Rcs phosphorelay, which represses flhDC, encoding the master flagellar regulator FlhD4C2. Mutants in rcsB, the response regulator in the Rcs phosphorelay, hyperswarm on solid agar and differentiate into swarmer cells in liquid, demonstrating that this system also influences the expression of genes central to differentiation. To gain a further understanding of RcsB-regulated genes involved in swarmer cell differentiation, transcriptome sequencing (RNA-Seq) was used to examine the RcsB regulon. Among the 133 genes identified, minC and minD, encoding cell division inhibitors, were identified as RcsB-activated genes. A third gene, minE, was shown to be part of an operon with minCD. To examine minCDE regulation, the min promoter was identified by 5' rapid amplification of cDNA ends (5'-RACE), and both transcriptional lacZ fusions and quantitative real-time reverse transcriptase (qRT) PCR were used to confirm that the minCDE operon was RcsB activated. Purified RcsB was capable of directly binding the minC promoter region. To determine the role of RcsB-mediated activation of minCDE in swarmer cell differentiation, a polar minC mutation was constructed. This mutant formed minicells during growth in liquid, produced shortened swarmer cells during differentiation, and exhibited decreased swarming motility. This work describes the regulation and role of the MinCDE cell division system in P. mirabilis swarming and swarmer cell elongation. Prior to this study, the mechanisms that inhibit cell division and allow swarmer cell elongation were unknown. In addition, this work outlines for the first time the RcsB regulon in P. mirabilis. Taken together, the data presented in this study begin to address how P. mirabilis elongates upon contact with a solid surface. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Evaluation of an improved prototype mini-baghouse to control the release of respirable crystalline silica from sand movers.

PubMed

Alexander, Barbara M; Esswein, Eric J; Gressel, Michael G; Kratzer, Jerry L; Feng, H Amy; Miller, Arthur L; Cauda, Emanuele; Heil, Graeham

2018-01-01

The OSHA final rule on respirable crystalline silica (RCS) will require hydraulic fracturing companies to implement engineering controls to limit workers' exposure to RCS. RCS is generated by pneumatic transfer of quartz-containing sand during hydraulic fracturing operations. Chronic inhalation of RCS can lead to serious disease, including silicosis and lung cancer. NIOSH research identified at least seven sources where RCS aerosols were generated at hydraulic fracturing sites. NIOSH researchers developed an engineering control to address one of the largest sources of RCS aerosol generation, RCS escaping from thief hatches on the top of sand movers. The control, the NIOSH Mini-Baghouse Retrofit Assembly (NMBRA), mounts on the thief hatches. Unlike most commercially available engineering controls, the NMBRA has no moving parts and requires no power source. This article details the results of an evaluation of generation 3 of the NMBRA at a sand mine in Arkansas from May 19-21, 2015. During the evaluation, 168 area air samples were collected at 12 locations on and around a sand mover with and without the NMBRA installed. Analytical results for respirable dust and RCS indicated the use of the NMBRA effectively reduced concentrations of both respirable dust and RCS downwind of the thief hatches. Reductions of airborne respirable dust were estimated at 99+%; reductions in airborne RCS ranged from 98-99%. Analysis of bulk samples of the dust showed the likely presence of freshly fractured quartz, a particularly hazardous form of RCS. Use of an improved filter fabric and a larger area of filter cloth led to substantial improvements in filtration and pressures during these trials, as compared to the generation 2 NMBRA. Planned future design enhancements, including a weather cover, will increase the performance and durability of the NMBRA. Future trials are planned to evaluate the long-term operability of the technology.

Tackling the tensions in evaluating capacity strengthening for health research in low- and middle-income countries

PubMed Central

Bates, Imelda; Boyd, Alan; Aslanyan, Garry; Cole, Donald C

2015-01-01

Strengthening research capacity in low- and middle-income countries is one of the most effective ways of advancing their health and development but the complexity and heterogeneity of health research capacity strengthening (RCS) initiatives means it is difficult to evaluate their effectiveness. Our study aimed to enhance understanding about these difficulties and to make recommendations about how to make health RCS evaluations more effective. Through discussions and surveys of health RCS funders, including the ESSENCE on Health Research initiative, we identified themes that were important to health RCS funders and used these to guide a systematic analysis of their evaluation reports. Eighteen reports, produced between 2000 and 2013, representing 12 evaluations, were purposefully selected from 54 reports provided by the funders to provide maximum variety. Text from the reports was extracted independently by two authors against a pre-designed framework. Information about the health RCS approaches, tensions and suggested solutions was re-constructed into a narrative. Throughout the process contacts in the health RCS funder agencies were involved in helping us to validate and interpret our results. The focus of the health RCS evaluations ranged from individuals and institutions to national, regional and global levels. Our analysis identified tensions around how much stakeholders should participate in an evaluation, the appropriate balance between measuring and learning and between a focus on short-term processes vs longer-term impact and sustainability. Suggested solutions to these tensions included early and ongoing stakeholder engagement in planning and evaluating health RCS, modelling of impact pathways and rapid assimilation of lessons learned for continuous improvement of decision making and programming. The use of developmental approaches could improve health RCS evaluations by addressing common tensions and promoting sustainability. Sharing learning about how to do robust and useful health RCS evaluations should happen alongside, not after, health RCS efforts. PMID:24717984

Effect of dexmedetomidine and cold stress in a rat model of neuropathic pain: Role of interleukin-6 and tumor necrosis factor-α.

PubMed

Farghaly, Hanan Sayed M; Mahmoud, Ahmed Mostafa; Abdel-Sater, Khaled A

2016-04-05

Dexmedetomidine (Dex) is a novel Alpha 2-adrenoceptor agonist. It decreases sympathetic tone and attenuates the stress responses to anesthesia and surgery. People exposed to cold suffer unpleasant thermal pain, which is experienced as stress and causes the release of noradrenaline from the sympathetic terminals. The present study investigated the effects of cold stress and dexmedetomidine on chronic constriction injury (CCI) model of the sciatic nerve in rats. Sixty four male Wistar rats were divided into seven groups of eight rats each: repeated cold stress (RCS) group, sham RCS group, CCI group, sham CCI group, Dex-treated group received a single dose of Dex (5 μg/kg), CCI+Dex group, CCI+RCS group. Interleukin-6 (IL-6) and tumor necrosis factor- alpha (TNF-α) levels in the serum were measured by enzyme-linked immunosorbent assay. The mean body weight of CCI, RCS, CCI+RCS, CCI+Dex and RCS+Dex groups decreased significantly compared with pre-values. Dexmedetomidine and CCI caused significant changes of the systolic, diastolic and mean blood pressure. Both RCS and CCI groups showed significant decreased of reaction time in the hot plate test. The RCS and CCI groups demonstrated a significant mechanical hyperalgesia, while pain threshold was increased in the RCS+Dex group. A significant decrease of serum IL-6 and TNF-α was demonstrated in CCI+RCS and CCI+Dex groups. The therapeutic effectiveness of dexmedetomidine in neuropathic pain may be through inhibition of proinflammatory cytokines, primarily IL-6 and TNF-α. Moreover, cold stress may result in increased resistance to neuropathic pain. Copyright © 2016 Elsevier B.V. All rights reserved.

Stage-discharge rating curves based on satellite altimetry and modeled discharge in the Amazon basin

NASA Astrophysics Data System (ADS)

Paris, Adrien; Dias de Paiva, Rodrigo; Santos da Silva, Joecila; Medeiros Moreira, Daniel; Calmant, Stephane; Garambois, Pierre-André; Collischonn, Walter; Bonnet, Marie-Paule; Seyler, Frederique

2016-05-01

In this study, rating curves (RCs) were determined by applying satellite altimetry to a poorly gauged basin. This study demonstrates the synergistic application of remote sensing and watershed modeling to capture the dynamics and quantity of flow in the Amazon River Basin, respectively. Three major advancements for estimating basin-scale patterns in river discharge are described. The first advancement is the preservation of the hydrological meanings of the parameters expressed by Manning's equation to obtain a data set containing the elevations of the river beds throughout the basin. The second advancement is the provision of parameter uncertainties and, therefore, the uncertainties in the rated discharge. The third advancement concerns estimating the discharge while considering backwater effects. We analyzed the Amazon Basin using nearly one thousand series that were obtained from ENVISAT and Jason-2 altimetry for more than 100 tributaries. Discharge values and related uncertainties were obtained from the rain-discharge MGB-IPH model. We used a global optimization algorithm based on the Monte Carlo Markov Chain and Bayesian framework to determine the rating curves. The data were randomly allocated into 80% calibration and 20% validation subsets. A comparison with the validation samples produced a Nash-Sutcliffe efficiency (Ens) of 0.68. When the MGB discharge uncertainties were less than 5%, the Ens value increased to 0.81 (mean). A comparison with the in situ discharge resulted in an Ens value of 0.71 for the validation samples (and 0.77 for calibration). The Ens values at the mouths of the rivers that experienced backwater effects significantly improved when the mean monthly slope was included in the RC. Our RCs were not mission-dependent, and the Ens value was preserved when applying ENVISAT rating curves to Jason-2 altimetry at crossovers. The cease-to-flow parameter of our RCs provided a good proxy for determining river bed elevation. This proxy was validated against Acoustic Doppler current profiler (ADCP) cross sections with an accuracy of more than 90%. Altimetry measurements are routinely delivered within a few days, and this RC data set provides a simple and cost-effective tool for predicting discharge throughout the basin in nearly real time.

Light scattering from normal and cervical cancer cells.

PubMed

Lin, Xiaogang; Wan, Nan; Weng, Lingdong; Zhou, Yong

2017-04-20

The light scattering characteristic plays a very important role in optic imaging and diagnostic applications. For optical detection of the cell, cell scattering characteristics have an extremely vital role. In this paper, we use the finite-difference time-domain (FDTD) algorithm to simulate the propagation and scattering of light in biological cells. The two-dimensional scattering cell models were set up based on the FDTD algorithm. The cell models of normal cells and cancerous cells were established, and the shapes of organelles, such as mitochondria, were elliptical. Based on these models, three aspects of the scattering characteristics were studied. First, the radar cross section (RCS) distribution curves of the corresponding cell models were calculated, then corresponding relationships between the size and the refractive index of the nucleus and light scattering information were analyzed in the three periods of cell canceration. The values of RCS increase positively with the increase of the nucleo-cytoplasmic ratio in the cancerous process when the scattering angle ranges from 0° to 20°. Second, the effect of organelles in the scattering was analyzed. The peak value of the RCS of cells with mitochondria is higher than the cells without mitochondria when the scattering angle ranges from 20° to 180°. Third, we demonstrated that the influence of cell shape is important, and the impact was revealed by the two typical ideal cells: round cells and oval cells. When the scattering angle ranges from 0° to 80°, the peak values and the frequencies of the appearance of the peaks from the two models are roughly similar. It can be concluded that: (1) the size of the nuclei and the change of the refractive index of cells have a certain impact on light scattering information of the whole cell; (2) mitochondria and other small organelles contribute to the cell light scattering characteristics in the larger scattering angle area; and (3) the change of the cell shape significantly influences the value of scattering peak and the deviation of scattering peak position. The results of the numerical simulation will guide subsequent experiments and early diagnosis of cervical cancer.

The Quantitative Reasoning for College Science (QuaRCS) Assessment in non-Astro 101 Courses II

NASA Astrophysics Data System (ADS)

Kirkman, Thomas W.; Jensen, Ellen

2017-06-01

The Quantitative Reasoning for College Science (QuaRCS) Assessment[1] aims to measure the pre-algebra mathematical skills that are often part of "general education" science courses like Astro 101. In four majors STEM classes, we report comparisons between QuaRCS metrics, ACT math, GPAO, and the course grade. In three of four classes QuaRCS QR score and ACT math were statistically significantly correlated (with r˜.6), however in the fourth course —a senior-level microbiology course— there was no statistically significantly correlation (in fact, r<0). In all courses —even in courses with seemingly little quantitative content— course grade was statistically significantly correlated to GPAO and QR. A QuaRCS metric aiming to report the students belief in the importance of math in science was seen to grow with the course level. Pre/post QuaRCS testing in Physics courses showed fractional sigma gains in QR, self-estimated math fluency and math importance, but not all of those increases were statistically significant. Using a QuaRCS map relating the questions to skill areas, we found graph reading, percentages, and proportional reasoning to be the most misunderstood skills in all four courses.[1] QuaRCS, Follette, et al.,2015, DOI: http://dx.doi.org/10.5038/1936-4660.8.2.2

Uptake and esterification of vitamin A by RCS rat retinal pigment epithelial cells in primary culture.

PubMed

Cia, David; Bonhomme, Brigitte; Azaïs-Braesco, Véronique; Cluzel, Jacques; Doly, Michel

2004-02-01

We investigated the capacity of Royal College of Surgeons (RCS) rat retinal pigment epithelial (RPE) cells to take up all-trans-retinol (ROL) (vitamin A) and to metabolize it into retinyl esters (RE). Cultures of RPE cells were established from RCS and control newborn rats. All-trans-ROL was delivered to the apical surface of the RPE monolayer. Retinoids were analyzed by high-performance liquid chromatography. The cellular retinol-binding protein type I (CRBP-I) was assessed by Western blotting. Before supplementation with ROL, RE were lower in RCS rats. After ROL supplementation, esters increased and reached values that were similar in the two strains, but the increase, expressed relative to the initial value, was higher in RCS rats. The uptake of ROL and the level of CRBP-I were greater in RCS rats. Our results provide evidence of a functional retinol esterifying enzyme in cultured RCS RPE cells and suggest that CRBP-I could play a role in the uptake and esterification of ROL in the RPE cells.

Advanced hypersonic aircraft design

NASA Technical Reports Server (NTRS)

Utzinger, Rob; Blank, Hans-Joachim; Cox, Craig; Harvey, Greg; Mckee, Mike; Molnar, Dave; Nagy, Greg; Petersen, Steve

1992-01-01

The objective of this design project is to develop the hypersonic reconnaissance aircraft to replace the SR-71 and to complement existing intelligence gathering devices. The initial design considerations were to create a manned vehicle which could complete its mission with at least two airborne refuelings. The aircraft must travel between Mach 4 and Mach 7 at an altitude of 80,000 feet for a maximum range of 12,000 nautical miles. The vehicle should have an air breathing propulsion system at cruise. With a crew of two, the aircraft should be able to take off and land on a 10,000 foot runway, and the yearly operational costs were not to exceed $300 million. Finally, the aircraft should exhibit stealth characteristics, including a minimized radar cross-section (RCS) and a reduced sonic boom. The technology used in this vehicle should allow for production between the years 1993 and 1995.

A Least-Squares Finite Element Method for Electromagnetic Scattering Problems

NASA Technical Reports Server (NTRS)

Wu, Jie; Jiang, Bo-nan

1996-01-01

The least-squares finite element method (LSFEM) is applied to electromagnetic scattering and radar cross section (RCS) calculations. In contrast to most existing numerical approaches, in which divergence-free constraints are omitted, the LSFF-M directly incorporates two divergence equations in the discretization process. The importance of including the divergence equations is demonstrated by showing that otherwise spurious solutions with large divergence occur near the scatterers. The LSFEM is based on unstructured grids and possesses full flexibility in handling complex geometry and local refinement Moreover, the LSFEM does not require any special handling, such as upwinding, staggered grids, artificial dissipation, flux-differencing, etc. Implicit time discretization is used and the scheme is unconditionally stable. By using a matrix-free iterative method, the computational cost and memory requirement for the present scheme is competitive with other approaches. The accuracy of the LSFEM is verified by several benchmark test problems.

Scattering Effects of Solar Panels on Space Station Antenna Performance

NASA Technical Reports Server (NTRS)

Panneton, Robert J.; Ngo, John C.; Hwu, Shian U.; Johnson, Larry A.; Elmore, James D.; Lu, Ba P.; Kelley, James S.

1994-01-01

Characterizing the scattering properties of the solar array panels is important in predicting Space Station antenna performance. A series of far-field, near-field, and radar cross section (RCS) scattering measurements were performed at S-Band and Ku-Band microwave frequencies on Space Station solar array panels. Based on investigation of the measured scattering patterns, the solar array panels exhibit similar scattering properties to that of the same size aluminum or copper panel mockup. As a first order approximation, and for worse case interference simulation, the solar array panels may be modeled using perfect reflecting plates. Numerical results obtained using the Geometrical Theory of Diffraction (GTD) modeling technique are presented for Space Station antenna pattern degradation due to solar panel interference. The computational and experimental techniques presented in this paper are applicable for antennas mounted on other platforms such as ship, aircraft, satellite, and space or land vehicle.

Fast optimization method of designing a wideband metasurface without using the Pancharatnam-Berry phase.

PubMed

Sui, Sai; Ma, Hua; Lv, Yueguang; Wang, Jiafu; Li, Zhiqiang; Zhang, Jieqiu; Xu, Zhuo; Qu, Shaobo

2018-01-22

Arbitrary control of electromagnetic waves remains a significant challenge although it promises many important applications. Here, we proposed a fast optimization method of designing a wideband metasurface without using the Pancharatnam-Berry (PB) phase, of which the elements are non-absorptive and capable of predicting the wideband and smooth phase-shift. In our design method, the metasurface is composed of low-Q-factor resonant elements without using the PB phase, and is optimized by the genetic algorithm and nonlinear fitting method, having the advantages that the far field scattering patterns can be quickly synthesized by the hybrid array patterns. To validate the design method, a wideband low radar cross section metasurface is demonstrated, showing good feasibility and performance of wideband RCS reduction. This work reveals an opportunity arising from a metasurface in effective manipulation of microwave and flexible fast optimal design method.

Passive coherent location direct signal suppression using hardware mixing techniques

NASA Astrophysics Data System (ADS)

Kaiser, Sean A.; Christianson, Andrew J.; Narayanan, Ram M.

2017-05-01

Passive coherent location (PCL) is a radar technique, in which the system uses reflections from opportunistic illumination sources in the environment for detection and tracking. Typically, PCL uses civilian communication transmitters not ideally suited for radar. The physical geometry of PCL is developed on the basis of bistatic radar without control of the transmitter antenna or waveform design. This poses the problem that often the receiver is designed with two antennas and channels, one for reference and one for surveillance. The surveillance channel is also contaminated with the direct signal and thus direct signal suppression (DSS) techniques must be used. This paper proposes an analytical solution based around hardware for DSS which is compared to other methods available in the literature. The methods are tested in varying bistatic geometries and with varying target radar cross section (RCS) and signal-to-noise ratio (SNR).

Achieving flexible low-scattering metasurface based on randomly distribution of meta-elements.

PubMed

Zhao, Junming; Sima, Boyu; Jia, Nan; Wang, Cheng; Zhu, Bo; Jiang, Tian; Feng, Yijun

2016-11-28

In the paper, a flexible low-scattering metasurface is proposed and realized. The layout is composed of similar "#" shaped elements with variable sizes which are randomly distributed along the surface. The various dimensions of the meta-elements lead to different reflection phases for the meta-elements with respect to the incident plane wave, resulting a diffuse reflection surface and exhibiting a broadband backward low-scattering property. In consideration of the flexibility, metasurfaces composed of printed metallic element films attaching with flexible substrate are designed, fabricated and measured in microwave domain. The measurement results show that 10dB radar cross section (RCS) reduction is obtained across the X-band by coating them to either metallic plates or metallic cylinders with only 1/8 working wavelength thickness. We think that the proposed flexible metasurface is applicable to other frequency bands and can be applied in EM stealth technology.

Joint Optimization of Receiver Placement and Illuminator Selection for a Multiband Passive Radar Network.

PubMed

Xie, Rui; Wan, Xianrong; Hong, Sheng; Yi, Jianxin

2017-06-14

The performance of a passive radar network can be greatly improved by an optimal radar network structure. Generally, radar network structure optimization consists of two aspects, namely the placement of receivers in suitable places and selection of appropriate illuminators. The present study investigates issues concerning the joint optimization of receiver placement and illuminator selection for a passive radar network. Firstly, the required radar cross section (RCS) for target detection is chosen as the performance metric, and the joint optimization model boils down to the partition p -center problem (PPCP). The PPCP is then solved by a proposed bisection algorithm. The key of the bisection algorithm lies in solving the partition set covering problem (PSCP), which can be solved by a hybrid algorithm developed by coupling the convex optimization with the greedy dropping algorithm. In the end, the performance of the proposed algorithm is validated via numerical simulations.

Investigation of High-alpha Lateral-directional Control Power Requirements for High-performance Aircraft

NASA Technical Reports Server (NTRS)

Foster, John V.; Ross, Holly M.; Ashley, Patrick A.

1993-01-01

Designers of the next-generation fighter and attack airplanes are faced with the requirements of good high-angle-of-attack maneuverability as well as efficient high speed cruise capability with low radar cross section (RCS) characteristics. As a result, they are challenged with the task of making critical design trades to achieve the desired levels of maneuverability and performance. This task has highlighted the need for comprehensive, flight-validated lateral-directional control power design guidelines for high angles of attack. A joint NASA/U.S. Navy study has been initiated to address this need and to investigate the complex flight dynamics characteristics and controls requirements for high-angle-of-attack lateral-directional maneuvering. A multi-year research program is underway which includes ground-based piloted simulation and flight validation. This paper will give a status update of this program that will include a program overview, description of test methodology and preliminary results.

Investigation of high-alpha lateral-directional control power requirements for high-performance aircraft

NASA Technical Reports Server (NTRS)

Foster, John V.; Ross, Holly M.; Ashley, Patrick A.

1993-01-01

Designers of the next-generation fighter and attack airplanes are faced with the requirements of good high angle-of-attack maneuverability as well as efficient high speed cruise capability with low radar cross section (RCS) characteristics. As a result, they are challenged with the task of making critical design trades to achieve the desired levels of maneuverability and performance. This task has highlighted the need for comprehensive, flight-validated lateral-directional control power design guidelines for high angles of attack. A joint NASA/U.S. Navy study has been initiated to address this need and to investigate the complex flight dynamics characteristics and controls requirements for high angle-of-attack lateral-directional maneuvering. A multi-year research program is underway which includes groundbased piloted simulation and flight validation. This paper will give a status update of this program that will include a program overview, description of test methodology and preliminary results.

Normal modes in an overmoded circular waveguide coated with lossy material

NASA Technical Reports Server (NTRS)

Lee, C. S.; Lee, S. W.; Chuang, S. L.

1985-01-01

The normal modes in an overmoded waveguide coated with a lossy material are analyzed, particularly for their attenuation properties as a function of coating material, layer thickness, and frequency. When the coating material is not too lossy, the low-order modes are highly attenuated even with a thin layer of coating. This coated guide serves as a mode suppressor of the low-order modes, which can be particularly useful for reducing the radar cross section (RCS) of a cavity structure such as a jet inlet. When the coating material is very lossy, low-order modes fall into two distinct groups: highly and lowly attenuated modes. However, as a/lambda (a = radius of the cylinder; lambda = the free-space wavelength) increases, the separation between these two groups becomes less distinctive. The attenuation constants of most of the low-order modes become small, and decrease as a function of lambda sup 2/a sup 3.

Propulsive Reaction Control System Model

NASA Technical Reports Server (NTRS)

Brugarolas, Paul; Phan, Linh H.; Serricchio, Frederick; San Martin, Alejandro M.

2011-01-01

This software models a propulsive reaction control system (RCS) for guidance, navigation, and control simulation purposes. The model includes the drive electronics, the electromechanical valve dynamics, the combustion dynamics, and thrust. This innovation follows the Mars Science Laboratory entry reaction control system design, and has been created to meet the Mars Science Laboratory (MSL) entry, descent, and landing simulation needs. It has been built to be plug-and-play on multiple MSL testbeds [analysis, Monte Carlo, flight software development, hardware-in-the-loop, and ATLO (assembly, test and launch operations) testbeds]. This RCS model is a C language program. It contains two main functions: the RCS electronics model function that models the RCS FPGA (field-programmable-gate-array) processing and commanding of the RCS valve, and the RCS dynamic model function that models the valve and combustion dynamics. In addition, this software provides support functions to initialize the model states, set parameters, access model telemetry, and access calculated thruster forces.

Effect of replacing maize silage with red clover silage in the diet on milk fatty acid composition in cows.

PubMed

Schulz, Franziska; Westreicher-Kristen, Edwin; Molkentin, Joachim; Knappstein, Karin; Susenbeth, Andreas

2018-05-16

This study aimed to evaluate the effect of replacing maize silage plus soybean meal with red clover silage (RCS) plus wheat on the fatty acid (FA) profile in the milk fat of cows. Forty-four lactating German Holstein cows were used in a 4 × 4 Latin square design with 21-d periods composed of 13 d of adaptation to diets followed by an 8-d sampling phase. Experimental diets offered as total mixed ration consisted of a constant forage-to-concentrate ratio (75:25) with target proportions of RCS to maize silage of 15:60 (RCS 15 ), 30:45 (RCS 30 ), 45:30 (RCS 45 ), and 60:15 (RCS 60 ) on a dry matter basis. Increasing the level of RCS in the diet was accompanied by a reduction of linoleic acid content in the diet and decreased linearly the proportions of linoleic acid in the milk up to 4%. Proportions of α-linolenic acid in milk increased 2-fold with RCS 60 compared with RCS 15 , which resulted from the linear increase in α-linolenic acid intake with incremental levels of RCS. Vaccenic acid in the milk fat was reduced by 24%. Rumenic acid, a conjugated linoleic acid (cis-9,trans-11 conjugated linoleic acid) considered to be a human health promoter, was also decreased by 22%. Reduced rumenic acid in the milk fat was probably due to a reduced amount of vaccenic acid produced in the rumen and, consequently, to the low amount of vaccenic acid to be desaturated to rumenic acid in the mammary gland by Δ 9 -desaturase. Oleic acid was enriched in the milk fat, although the dietary concentration of oleic acid decreased. Stearic acid proportions remained constant with increasing levels of RCS. The proportions of total polyunsaturated FA were increased by 12%, and the long-chain FA proportions increased linearly with increasing levels of RCS. Myristic acid was reduced linearly, but palmitic acid remained constant. Saturated FA was reduced linearly by 2%. Branched-chain FA, which are presumed to possess anticarcinogenic properties, were reduced to a small extent only (quadratic effect). We conclude that replacing maize silage with RCS appears to alter milk FA composition by reducing linoleic acid intake and ruminal biohydrogenation. Feeding RCS represents a strategy to increase intake of α-linolenic acid in dairy cows. However, because changes in the FA profile show positive as well as negative effects, no distinct conclusions can be drawn with regard to human health benefits. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Metallographic Preparation of Space Shuttle Reaction Control System Thruster Electron Beam Welds for Electron Backscatter Diffraction

NASA Technical Reports Server (NTRS)

Martinez, James

2011-01-01

A Space Shuttle Reaction Control System (RCS) thruster failed during a firing test at the NASA White Sands Test Facility (WSTF), Las Cruces, New Mexico. The firing test was being conducted to investigate a previous electrical malfunction. A number of cracks were found associated with the fuel closure plate/injector assembly (Fig 1). The firing test failure generated a flight constraint to the launch of STS-133. A team comprised of several NASA centers and other research institutes was assembled to investigate and determine the root cause of the failure. The JSC Materials Evaluation Laboratory was asked to compare and characterize the outboard circumferential electron beam (EB) weld between the fuel closure plate (Titanium 6Al-4V) and the injector (Niobium C-103 alloy) of four different RCS thrusters, including the failed RCS thruster. Several metallographic challenges in grinding/polishing, and particularly in etching were encountered because of the differences in hardness, ductility, and chemical resistance between the two alloys and the bimetallic weld. Segments from each thruster were sectioned from the outboard weld. The segments were hot-compression mounted using a conductive, carbon-filled epoxy. A grinding/polishing procedure for titanium alloys was used [1]. This procedure worked well on the titanium; but a thin, disturbed layer was visible on the niobium surface by means of polarized light. Once polished, each sample was micrographed using bright field, differential interference contrast optical microscopy, and scanning electron microscopy (SEM) using a backscatter electron (BSE) detector. No typical weld anomalies were observed in any of the cross sections. However, areas of large atomic contrast were clearly visible in the weld nugget, particularly along fusion line interfaces between the titanium and the niobium. This prompted the need to better understand the chemistry and microstructure of the weld (Fig 2). Energy Dispersive X-Ray Spectroscopy (EDS) was used to confirm the chemical composition of the variations in contrast in these areas. Niobium alloys generally require exposure to more aggressive chemical reagents than titanium alloys for etching because of niobium s chemical resistance; therefore, the titanium portion of the sample was etched first. A five second immersion in Kroll s reagent revealed a general microstructure on the titanium portion of the sample; however, the titanium heat affected zone closest to the weld, was over-etched due to higher concentrations of refined grains and an increase in eta-phase. The Kroll s etchant also revealed some microstructure in the weld nugget itself; the niobium portion of the sample remained unetched.

Rcs and PhoPQ regulatory overlap in the control of Salmonella enterica virulence.

PubMed

García-Calderón, Clara B; Casadesús, Josep; Ramos-Morales, Francisco

2007-09-01

Genetic screens based on the use of MudJ-generated lac fusions permitted the identification of novel genes regulated by the Rcs signal transduction system in Salmonella enterica serovar Typhimurium. Besides genes that are also found in the Escherichia coli genome, our screens identified Salmonella-specific genes regulated by RcsB, including bapA, siiE, srfA, and srfB. Here we show that the srfABC operon is negatively regulated by RcsB and by PhoP. In vivo studies using mutants with constitutive activation of the Rcs and/or PhoPQ system suggested that there is an overlap between these regulatory systems in the control of Salmonella virulence.

The Development and Testing of a Prototype Mini-Baghouse to Control the Release of Respirable Crystalline Silica from Sand Movers

PubMed Central

Alexander, Barbara M.; Esswein, Eric J.; Gressel, Michael G.; Kratzer, Jerry L.; Feng, H. Amy; King, Bradley; Miller, Arthur L.; Cauda, Emanuele

2016-01-01

Inhalation of respirable crystalline silica (RCS) is a significant risk to worker health during well completions operations (which include hydraulic fracturing) at conventional and unconventional oil and gas extraction sites. RCS is generated by pneumatic transfer of quartz-containing sand during hydraulic fracturing operations. National Institute for Occupational Safety and Health (NIOSH) researchers identified concentrations of RCS at hydraulic fracturing sites that exceed 10 times the Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) and up to 50 times the NIOSH Recommended Exposure Limit (REL). NIOSH research identified at least seven point sources of dust release at contemporary oil and gas extraction sites where RCS aerosols were generated. NIOSH researchers recommend the use of engineering controls wherever they can be implemented to limit the RCS released. A control developed to address one of the largest sources of RCS aerosol generation is the NIOSH mini-baghouse assembly, mounted on the thief hatches on top of the sand mover. This manuscript details the results of a trial of the NIOSH mini-baghouse at a sand mine in Arkansas, November 18 – 21, 2013. During the trial, area air samples were collected at 12 locations on and around a sand mover with and without the mini-baghouse control installed. Analytical results for respirable dust and RCS indicate the use of the mini-baghouse effectively reduced both respirable dust and RCS downwind of the thief hatches. Reduction of airborne respirable dust ranged from 85% to 98%; reductions in airborne RCS ranged from 79% to 99%. A bulk sample of dust collected by the baghouse assembly showed the likely presence of freshly fractured quartz, a particularly hazardous form of RCS. Planned future design enhancements will increase the performance and durability of the mini-baghouse, including an improved bag clamp mechanism and upgraded filter fabric with a modified air-to-cloth ratio. Future trials are planned to determine additional respirable dust and RCS concentration reductions achieved through these design changes. PMID:27003622

Antiviral effects of black raspberry (Rubus coreanus) seed extract and its polyphenolic compounds on norovirus surrogates.

PubMed

Lee, Ji-Hye; Bae, Sun Young; Oh, Mi; Seok, Jong Hyeon; Kim, Sella; Chung, Yeon Bin; Gowda K, Giri; Mun, Ji Young; Chung, Mi Sook; Kim, Kyung Hyun

2016-06-01

Black raspberry seeds, a byproduct of wine and juice production, contain large quantities of polyphenolic compounds. The antiviral effects of black raspberry seed extract (RCS) and its fraction with molecular weight less than 1 kDa (RCS-F1) were examined against food-borne viral surrogates, murine norovirus-1 (MNV-1) and feline calicivirus-F9 (FCV-F9). The maximal antiviral effect was achieved when RCS or RCS-F1 was added simultaneously to cells with MNV-1 or FCV-F9, reaching complete inhibition at 0.1-1 mg/mL. Transmission electron microscopy (TEM) images showed enlarged viral capsids or disruption (from 35 nm to up to 100 nm) by RCS-F1. Our results thus suggest that RCS-F1 can interfere with the attachment of viral surface protein to host cells. Further, two polyphenolic compounds derived from RCS-F1, cyanidin-3-glucoside (C3G) and gallic acid, identified by liquid chromatography-tandem mass spectrometry, showed inhibitory effects against the viruses. C3G was suggested to bind to MNV-1 RNA polymerase and to enlarge viral capsids using differential scanning fluorimetry and TEM, respectively.

Expression of heat shock protein in the atrophic corneal epithelium of the Royal College of Surgeons dystrophic rat.

PubMed

Yamaguchi, K; Yamaguchi, K; Sheedlo, H J; Turner, J E

1991-03-01

We report atrophic changes in the corneal epithelium of Royal College of Surgeons (RCS) dystrophic rats. The thickness of the corneal epithelium of 180-day-old RCS dystrophic rats was significantly decreased compared to that of 26-day-old RCS dystrophic and age-matched Sprague-Dawley (SD) rats. Immunostaining for (Na+ + K+) ATPase in the corneal epithelium of 180-day-old RCS dystrophic rats was dramatically reduced when compared to that of 26-day-old RCS dystrophic and age-matched SD rats. In contrast, heat shock protein immunostaining in the corneal epithelium was dense in all of the basal cells, wing cells, and superficial cells of 180-day-old RCS dystrophic rats but was minimally observed in some of the basal cells and in fewer wing and superficial cells of the corneal epithelium of 26-day-old RCS dystrophic and age-matched SD rats. We speculate that toxic products from the degenerating rod outer segments in the course of retinal dystrophy may affect the corneal epithelium, resulting in its atrophy. It is also possible that heat shock proteins appear in the atrophic corneal epithelium due to its degenerative condition.

Characterization of Aerodynamic Interactions with the Mars Science Laboratory Reaction Control System Using Computation and Experiment

NASA Technical Reports Server (NTRS)

Schoenenberger, Mark; VanNorman, John; Rhode, Matthew; Paulson, John

2013-01-01

On August 5 , 2012, the Mars Science Laboratory (MSL) entry capsule successfully entered Mars' atmosphere and landed the Curiosity rover in Gale Crater. The capsule used a reaction control system (RCS) consisting of four pairs of hydrazine thrusters to fly a guided entry. The RCS provided bank control to fly along a flight path commanded by an onboard computer and also damped unwanted rates due to atmospheric disturbances and any dynamic instabilities of the capsule. A preliminary assessment of the MSL's flight data from entry showed that the capsule flew much as predicted. This paper will describe how the MSL aerodynamics team used engineering analyses, computational codes and wind tunnel testing in concert to develop the RCS system and certify it for flight. Over the course of MSL's development, the RCS configuration underwent a number of design iterations to accommodate mechanical constraints, aeroheating concerns and excessive aero/RCS interactions. A brief overview of the MSL RCS configuration design evolution is provided. Then, a brief description is presented of how the computational predictions of RCS jet interactions were validated. The primary work to certify that the RCS interactions were acceptable for flight was centered on validating computational predictions at hypersonic speeds. A comparison of computational fluid dynamics (CFD) predictions to wind tunnel force and moment data gathered in the NASA Langley 31-Inch Mach 10 Tunnel was the lynch pin to validating the CFD codes used to predict aero/RCS interactions. Using the CFD predictions and experimental data, an interaction model was developed for Monte Carlo analyses using 6-degree-of-freedom trajectory simulation. The interaction model used in the flight simulation is presented.

A perspective on reagent diversity and non-covalent binding of reactive carbonyl species (RCS) and effector reagents in nonenzymatic glycation (NEG): Mechanistic considerations and implications for future research

NASA Astrophysics Data System (ADS)

Rodnick, Kenneth J.; Holman, R. W.; Ropski, Pamela S.; Huang, Mingdong; Swislocki, Arthur L. M.

2017-06-01

This perspective focuses on illustrating the underappreciated connections between reactive carbonyl species (RCS), initial binding in the nonenzymatic glycation (NEG) process, and nonenzymatic covalent protein modification (here termed NECPM). While glucose is the central species involved in NEG, recent studies indicate that the initially-bound glucose species in the NEG of human hemoglobin (HbA) and human serum albumin (HSA) are non-RCS ring-closed isomers. The ring-opened glucose, an RCS structure that reacts in the NEG process, is most likely generated from previously-bound ring-closed isomers undergoing concerted acid/base reactions while bound to protein. The generation of the glucose RCS can involve concomitantly-bound physiological species (e.g., inorganic phosphate, water, etc.); here termed effector reagents. Extant NEG schemes do not account for these recent findings. In addition, effector reagent reactions with glucose in the serum and erythrocyte cytosol can generate RCS (e.g., glyoxal, glyceraldehyde, etc.). Recent research has shown that these RCS covalently modify proteins in vivo via NECPM mechanisms. A general scheme that reflects both the reagent and mechanistic diversity that can lead to NEG and NECPM is presented here. A perspective that accounts for the relationships between RCS, NEG, and NECPM can facilitate the understanding of site selectivity, may help explain overall glycation rates, and may have implications for the clinical assessment/control of diabetes mellitus. In view of this perspective, concentrations of ribose, fructose, Pi, bicarbonate, counter ions, and the resulting RCS generated within intracellular and extracellular compartments may be of importance and of clinical relevance. Future research is also proposed.

Graphene based tunable fractal Hilbert curve array broadband radar absorbing screen for radar cross section reduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Xianjun, E-mail: xianjun.huang@manchester.ac.uk; College of Electronic Science and Engineering, National University of Defense Technology, Changsha 410073; Hu, Zhirun

2014-11-15

This paper proposes a new type of graphene based tunable radar absorbing screen. The absorbing screen consists of Hilbert curve metal strip array and chemical vapour deposition (CVD) graphene sheet. The graphene based screen is not only tunable when the chemical potential of the graphene changes, but also has broadband effective absorption. The absorption bandwidth is from 8.9GHz to 18.1GHz, ie., relative bandwidth of more than 68%, at chemical potential of 0eV, which is significantly wider than that if the graphene sheet had not been employed. As the chemical potential varies from 0 to 0.4eV, the central frequency of themore » screen can be tuned from 13.5GHz to 19.0GHz. In the proposed structure, Hilbert curve metal strip array was designed to provide multiple narrow band resonances, whereas the graphene sheet directly underneath the metal strip array provides tunability and averagely required surface resistance so to significantly extend the screen operation bandwidth by providing broadband impedance matching and absorption. In addition, the thickness of the screen has been optimized to achieve nearly the minimum thickness limitation for a nonmagnetic absorber. The working principle of this absorbing screen is studied in details, and performance under various incident angles is presented. This work extends applications of graphene into tunable microwave radar cross section (RCS) reduction applications.« less

Shedding Light on the Nature of Seminal Round Cells

PubMed Central

Palermo, Gianpiero D.; Neri, Queenie V.; Cozzubbo, Tyler; Cheung, Stephanie; Pereira, Nigel; Rosenwaks, Zev

2016-01-01

Introduction In this investigation we assess the incidence of round cells (RCs) in semen samples in our infertile patient population and their significance on intracytoplasmic sperm injection (ICSI) cycle outcomes. We also evaluate the usefulness of RCs as indicators of bacterial infection and highlight the origin of this cell-type, as well as its role in the human ejaculate. Patients and Methods In a prospective fashion, a total of 4,810 ejaculated samples were included in the study during a period of 24 months. RCs were characterized for white blood cell (WBC) components versus exfoliated germ cells by testing for multiple markers of ploidy as well as protamine assays. Cases displaying ≥ 2 x 106/ml RCs were screened for bacteria. Raw specimens containing RC were processed by peroxidase and other leukocyte assays, specific stains for protamines were used to identify spermiogenic stage, aneuploidy (FISH) assessment was carried out, and the presence of various Sertoli-cell cytoplasmic remnants was analyzed to identify and characterize immature germ cells. The effect of RC on clinical outcome was assessed in specimens used for ICSI. Results The average age of the men involved was 39.2 ± 7 years. Semen samples had a mean concentration of 40.7 ± 31 x 106/ml, motility of 42.6 ± 35%, and morphology of 2.3 ± 2%. RCs were identified in 261 specimens, representing a proportion of 5.4%. Men with RCs had comparable age but lower sperm concentration and morphology than the control group (P<0.001). The aneuploidy rate of 4.3% in RCs group was remarkably higher than the control group (2.3%; P<0.001). Sperm aneuploidy rate positively correlated with the number of RCs (P<0.001). Of 44 men, 17 of them in 18 cycles had up to 1.9 x 106/ml RCs without affecting fertilization and clinical pregnancy rates when compared to controls (n = 365 cycles). In 27 men undergoing 33 ICSI cycles with ≥ 2 x 106/ml RCs, the fertilization rate trended lower and the miscarriage rate was significantly increased (P = 0.05). There was lack of correlation between RC and bacteriological growth. Specific markers indicated that seminal RCs are mostly immature germ cells encased in the remnants of Sertoli cell cytoplasm. Moreover, their modest protamine content and their haploid status confirm that they are post-meiotic. Sequential observation in the same man showed that RC episodes were followed by an amelioration of semen parameters, and interestingly, the episodic occurrence of RCs often coincides with flu season peaks. Conclusions Seminal RCs are not a marker of infectiousness but rather a transient indicator of spermatogenic insult that possibly occurs in most men following a mild and transient ailment such as the flu. PMID:26982590

77 FR 13369 - Biweekly Notice Applications and Amendments to Facility Operating Licenses Involving No...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-06

...] Leakage Detection Systems,'' to define a new time limit for restoring inoperable RCS leakage detection instrumentation to operable status, establish alternate methods of monitoring RCS leakage when monitors are... design bases related to the operability of the RCS leakage detection instrumentation. Date of issuance...

75 FR 79048 - Notice of Availability of the Models for Plant-Specific Adoption of Technical Specifications Task...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-17

... Specifications (STS) to define a new time limit for restoring inoperable RCS leakage detection instrumentation to... operability of the RCS leakage detection instrumentation. The CLIIP model SE will facilitate expedited... Operability Requirements and Actions for RCS Leakage Instrumentation'' AGENCY: Nuclear Regulatory Commission...

76 FR 37845 - Biweekly Notice; Applications and Amendments to Facility Operating Licenses Involving No...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-28

... define a new time limit for restoring inoperable Reactor Coolant System (RCS) leakage detection... RCS leakage detection instrumentation. These changes are consistent with NRC-approved Revision 3 to...? Response: No. The proposed change clarifies the operability requirements for the RCS leakage detection...

76 FR 31369 - Biweekly Notice; Applications and Amendments to Facility Operating Licenses Involving No...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-31

... detection instrumentation to operable status; establish alternate methods of monitoring RCS leakage when one... the RCS leakage detection instrumentation. These changes are consistent with NRC-approved Revision 3... requirements for the RCS leakage detection instrumentation and reduces the time allowed for the plant to...

Development of the Research Competencies Scale

ERIC Educational Resources Information Center

Swank, Jacqueline M.; Lambie, Glenn W.

2016-01-01

The authors present the development of the Research Competencies Scale (RCS). The purpose of this article is threefold: (a) present a rationale for the RCS, (b) review statistical analysis procedures used in developing the RCS, and (c) offer implications for counselor education, the enhancement of scholar-researchers, and future research.

Evaluation of Honeywell Recoverable Computer System (RCS) in Presence of Electromagnetic Effects

NASA Technical Reports Server (NTRS)

Malekpour, Mahyar

1997-01-01

The design and development of a Closed-Loop System to study and evaluate the performance of the Honeywell Recoverable Computer System (RCS) in electromagnetic environments (EME) is presented. The development of a Windows-based software package to handle the time critical communication of data and commands between the RCS and flight simulation code in real-time, while meeting the stringent hard deadlines is also presented. The performance results of the RCS while exercising flight control laws under ideal conditions as well as in the presence of electromagnetic fields is also discussed.

Novel mechanism for scavenging of hypochlorite involving a periplasmic methionine-rich peptide and methionine sulfoxide reductase

DOE PAGES

Melnyk, Ryan A.; Youngblut, Matthew D.; Clark, Iain C.; ...

2015-05-12

Reactive chlorine species (RCS) defense mechanisms are important for bacterial fitness in diverse environments. In addition to the anthropogenic use of RCS in the form of bleach, these compounds are also produced naturally through photochemical reactions of natural organic matter and in vivo by the mammalian immune system in response to invading microorganisms. To gain insight into bacterial RCS defense mechanisms, we investigated Azospira suillum strain PS, which produces periplasmic RCS as an intermediate of perchlorate respiration. Our studies identified an RCS response involving an RCS stress-sensing sigma/anti-sigma factor system (SigF/NrsF), a soluble hypochlorite-scavenging methionine-rich periplasmic protein (MrpX), and amore » putative periplasmic methionine sulfoxide reductase (YedY1). We investigated the underlying mechanism by phenotypic characterization of appropriate gene deletions, chemogenomic profiling of barcoded transposon pools, transcriptome sequencing, and biochemical assessment of methionine oxidation. Our results demonstrated that SigF was specifically activated by RCS and initiated the transcription of a small regulon centering around yedY1 and mrpX. A yedY1 paralog ( yedY2) was found to have a similar fitness to yedY1 despite not being regulated by SigF. Markerless deletions of yedY2 confirmed its synergy with the SigF regulon. MrpX was strongly induced and rapidly oxidized by RCS, especially hypochlorite. Our results suggest a mechanism involving hypochlorite scavenging by sacrificial oxidation of the MrpX in the periplasm. Reduced MrpX is regenerated by the YedY methionine sulfoxide reductase activity. The phylogenomic distribution of this system revealed conservation in several Proteobacteria of clinical importance, including uropathogenic Escherichia coli and Brucella spp., implying a putative role in immune response evasion in vivo. In addition, bacteria are often stressed in the environment by reactive chlorine species (RCS) of either anthropogenic or natural origin, but little is known of the defense mechanisms they have evolved. Using a microorganism that generates RCS internally as part of its respiratory process allowed us to uncover a novel defense mechanism based on RCS scavenging by reductive reaction with a sacrificial methionine-rich peptide and redox recycling through a methionine sulfoxide reductase. As a result, this system is conserved in a broad diversity of organisms, including some of clinical importance, invoking a possible important role in innate immune system evasion.« less

Macrophage cell activation with acute apical abscess contents determined by interleukin-1 Beta and tumor necrosis factor alpha production.

PubMed

Sousa, Ezilmara L R; Martinho, Frederico C; Leite, Fabio R M; Nascimento, Gustavo G; Gomes, Brenda P F A

2014-11-01

This clinical study has investigated the antigenic activity of bacterial contents from exudates of acute apical abscesses (AAAs) and their paired root canal contents regarding the stimulation capacity by levels of interleukin (IL)-1 beta and tumor necrosis factor alpha (TNF-α) throughout the root canal treatment against macrophage cells. Paired samples of infected root canals and exudates of AAAs were collected from 10 subjects. Endodontic contents were sampled before (root canal sample [RCS] 1) and after chemomechanical preparation (RCS2) and after 30 days of intracanal medication with calcium hydroxide + chlorhexidine gel (Ca[OH]2 + CHX gel) (RCS3). Polymerase chain reaction (16S rDNA) was used for detection of the target bacteria, whereas limulus amebocyte lysate was used to measure endotoxin levels. Raw 264.7 macrophages were stimulated with AAA exudates from endodontic contents sampled in different moments of root canal treatment. Enzyme-linked immunosorbent assays were used to measure the levels of TNF-α and IL-1 beta. Parvimonas micra, Porphyromonas endodontalis, Dialister pneumosintes, and Prevotella nigrescens were the most frequently detected species. Higher levels of endotoxins were found in samples from periapical exudates at RCS1 (P < .005). In fact, samples collected from periapical exudates showed a higher stimulation capacity at RCS1 (P < .05). A positive correlation was found between endotoxins from exudates with IL-1 beta (r = 0.97) and TNF-α (r = 0.88) production (P < .01). The significant reduction of endotoxins and bacterial species achieved by chemomechanical procedures (RCS2) resulted in a lower capacity of root canal contents to stimulate the cells compared with that at RCS1 (P < .05). The use of Ca(OH)2 + CHX gel as an intracanal medication (RCS3) improved the removal of endotoxins and bacteria from infected root canals (P < .05) whose contents induced a lower stimulation capacity against macrophages cells at RCS1, RCS2, and RCS3 (P < .05). AAA exudates showed higher levels of endotoxins and showed a greater capacity of macrophage stimulation than the paired root canal samples. Moreover, the use of intracanal medication improved the removal of bacteria and endotoxins from infected root canals, which may have resulted in the reduction of the inflammatory potential of the root canal content. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Novel mechanism for scavenging of hypochlorite involving a periplasmic methionine-rich peptide and methionine sulfoxide reductase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Melnyk, Ryan A.; Youngblut, Matthew D.; Clark, Iain C.

Reactive chlorine species (RCS) defense mechanisms are important for bacterial fitness in diverse environments. In addition to the anthropogenic use of RCS in the form of bleach, these compounds are also produced naturally through photochemical reactions of natural organic matter and in vivo by the mammalian immune system in response to invading microorganisms. To gain insight into bacterial RCS defense mechanisms, we investigated Azospira suillum strain PS, which produces periplasmic RCS as an intermediate of perchlorate respiration. Our studies identified an RCS response involving an RCS stress-sensing sigma/anti-sigma factor system (SigF/NrsF), a soluble hypochlorite-scavenging methionine-rich periplasmic protein (MrpX), and amore » putative periplasmic methionine sulfoxide reductase (YedY1). We investigated the underlying mechanism by phenotypic characterization of appropriate gene deletions, chemogenomic profiling of barcoded transposon pools, transcriptome sequencing, and biochemical assessment of methionine oxidation. Our results demonstrated that SigF was specifically activated by RCS and initiated the transcription of a small regulon centering around yedY1 and mrpX. A yedY1 paralog ( yedY2) was found to have a similar fitness to yedY1 despite not being regulated by SigF. Markerless deletions of yedY2 confirmed its synergy with the SigF regulon. MrpX was strongly induced and rapidly oxidized by RCS, especially hypochlorite. Our results suggest a mechanism involving hypochlorite scavenging by sacrificial oxidation of the MrpX in the periplasm. Reduced MrpX is regenerated by the YedY methionine sulfoxide reductase activity. The phylogenomic distribution of this system revealed conservation in several Proteobacteria of clinical importance, including uropathogenic Escherichia coli and Brucella spp., implying a putative role in immune response evasion in vivo. In addition, bacteria are often stressed in the environment by reactive chlorine species (RCS) of either anthropogenic or natural origin, but little is known of the defense mechanisms they have evolved. Using a microorganism that generates RCS internally as part of its respiratory process allowed us to uncover a novel defense mechanism based on RCS scavenging by reductive reaction with a sacrificial methionine-rich peptide and redox recycling through a methionine sulfoxide reductase. As a result, this system is conserved in a broad diversity of organisms, including some of clinical importance, invoking a possible important role in innate immune system evasion.« less

Role of Reconstructive Surgery (RCS) in Improving the Quality of Life of Leprosy Afflicted Persons.

PubMed

Lenka, D; Mahapatra, A

2016-01-01

Since time immemorial, stigma has been associated with leprosy mainly due to deformity and disability which in turn affects the physical, psychological, social and economical well being of some of the leprosy afflicted persons (LAPs). To prevent and correct deformities Government of India has focused on early diagnosis and appropriate treatment. In addition government has been providing services of Reconstructive Surgery (RCS). RCS corrects the deformity and is expected to help in reducing the stigma in society and reintegrate the affected persons in to society so that they become economically self reliant and carry out their normal livelihood activities without any prejudice. As the stigma has cultural background, this study has.been carried out with to assess the existing stigma level in pre RCS in society in parts of Odisha and compare with that of post RCS. The study was conducted in Sonepur district of Odisha. The sample size is the entire universe of all the 60 patients who had undergone the RCS process, during these the recent years. The methods adopted for data collection were the tools like questionnaire schedules, interview, observation, FGD and in depth case studies. Almost 86% of these Leprosy afflicted persons (LAPs) were very satisfied due to improvement in acceptance by their family, friend, relatives and society after surgery because of the correction of deformity by RCS as it enabled them to get back into normal life. The economical status improved in 8/60 (13%) after RCS, some becoming capable of earning more than Rs. 10,000/- per month after RCS. To conclude, in this settings of Sonepur (Odisha). RCS appeared to help the LAPs in improving their social acceptance thereby reducing stigma and also improving their economic status thus empowering them to lead their life as a normal human beings. There is need to enlarge and expand these studies to other parts of state/region so that the link with beliefs, type of disabilities and also type of surgery could be better understood and the knowledge generated could be applied to get optimum results.

Immunohistochemical analysis of FoxP3+ cells in periapical granulomas and radicular cysts.

PubMed

Peixoto, Raniel Fernandes; Pereira, Joabe dos Santos; Nonaka, Cassiano Francisco Weege; Silveira, Ericka Janine Dantas da; Miguel, Márcia Cristina da Costa

2012-09-01

To compare the number of FoxP3(+) cells between periapical granulomas (PGs) and radicular cysts (RCs), and to correlate this number with the intensity of the inflammatory infiltrate in these lesions and with epithelial thickness of RCs. Thirty PGs and 30 RCs were submitted to immunohistochemical analysis using an anti-FoxP3 polyclonal antibody. FoxP3(+) cells were counted under a light microscope (×400 magnification) in five fields and the mean value was calculated for each specimen. Statistical tests were used to evaluate differences in the number of FoxP3(+) cells according to type of lesion (PG vs. RC), intensity of the inflammatory infiltrate (grade I/II vs. grade III), and epithelial thickness of RCs (atrophic vs. hyperplastic). FoxP3(+) cells were detected in most PGs (93.3%) and RCs (93.3%). The median number of FoxP3(+) cells was 2.40 in PGs and 1.00 in RCs, with this difference being statistically significant (P=0.005). No significant differences in the number of FoxP3(+) cells were observed in terms of the intensity of the inflammatory infiltrate (P=0.465) or epithelial thickness of RCs (P=0.737). The present results suggest a greater participation of regulatory T cells in the modulation of the inflammatory response in PGs. In addition, the presence of a less effective regulatory environment in RCs, together with the high levels of inflammatory mediators as reported in the literature, may contribute to the greater growth potential of these lesions. Copyright © 2012 Elsevier Ltd. All rights reserved.

Robotic-assisted versus laparoscopic colorectal surgery: a meta-analysis of four randomized controlled trials

PubMed Central

2014-01-01

Background Robotic-assisted laparoscopy is popularly performed for colorectal disease. The objective of this meta-analysis was to compare the safety and efficacy of robotic-assisted colorectal surgery (RCS) and laparoscopic colorectal surgery (LCS) for colorectal disease based on randomized controlled trial studies. Methods Literature searches of electronic databases (Pubmed, Web of Science, and Cochrane Library) were performed to identify randomized controlled trial studies that compared the clinical or oncologic outcomes of RCS and LCS. This meta-analysis was performed using the Review Manager (RevMan) software (version 5.2) that is provided by the Cochrane Collaboration. The data used were mean differences and odds ratios for continuous and dichotomous variables, respectively. Fixed-effects or random-effects models were adopted according to heterogeneity. Results Four randomized controlled trial studies were identified for this meta-analysis. In total, 110 patients underwent RCS, and 116 patients underwent LCS. The results revealed that estimated blood losses (EBLs), conversion rates and times to the recovery of bowel function were significantly reduced following RCS compared with LCS. There were no significant differences in complication rates, lengths of hospital stays, proximal margins, distal margins or harvested lymph nodes between the two techniques. Conclusions RCS is a promising technique and is a safe and effective alternative to LCS for colorectal surgery. The advantages of RCS include reduced EBLs, lower conversion rates and shorter times to the recovery of bowel function. Further studies are required to define the financial effects of RCS and the effects of RCS on long-term oncologic outcomes. PMID:24767102

Drosophila E-cadherin is required for the maintenance of ring canals anchoring to mechanically withstand tissue growth

PubMed Central

Loyer, Nicolas; Kolotuev, Irina; Pinot, Mathieu; Le Borgne, Roland

2015-01-01

Intercellular bridges called “ring canals” (RCs) resulting from incomplete cytokinesis play an essential role in intercellular communication in somatic and germinal tissues. During Drosophila oogenesis, RCs connect the maturing oocyte to nurse cells supporting its growth. Despite numerous genetic screens aimed at identifying genes involved in RC biogenesis and maturation, how RCs anchor to the plasma membrane (PM) throughout development remains unexplained. In this study, we report that the clathrin adaptor protein 1 (AP-1) complex, although dispensable for the biogenesis of RCs, is required for the maintenance of the anchorage of RCs to the PM to withstand the increased membrane tension associated with the exponential tissue growth at the onset of vitellogenesis. Here we unravel the mechanisms by which AP-1 enables the maintenance of RCs’ anchoring to the PM during size expansion. We show that AP-1 regulates the localization of the intercellular adhesion molecule E-cadherin and that loss of AP-1 causes the disappearance of the E-cadherin–containing adhesive clusters surrounding the RCs. E-cadherin itself is shown to be required for the maintenance of the RCs’ anchorage, a function previously unrecognized because of functional compensation by N-cadherin. Scanning block-face EM combined with transmission EM analyses reveals the presence of interdigitated, actin- and Moesin-positive, microvilli-like structures wrapping the RCs. Thus, by modulating E-cadherin trafficking, we show that the sustained E-cadherin–dependent adhesion organizes the microvilli meshwork and ensures the proper attachment of RCs to the PM, thereby counteracting the increasing membrane tension induced by exponential tissue growth. PMID:26424451

32 CFR 50.7 - Information requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 32 National Defense 1 2012-07-01 2012-07-01 false Information requirements. 50.7 Section 50.7 National Defense Department of Defense OFFICE OF THE SECRETARY OF DEFENSE PERSONNEL, MILITARY AND CIVILIAN... been assigned Report Control Symbol (RCS) DD-P&R(Q)2182 in accordance with DoD 8910.1-M. 12 12 See...

Characterization of the RcsC sensor kinase from Erwinia amylovora and other enterobacteria

USDA-ARS?s Scientific Manuscript database

RcsC is a hybrid sensor kinase which contains a sensor domain, a histidine kinase domain and a receiver domain. We have previously demonstrated that, while the Erwinia amylovora rcsC mutant produces more amylovoran than the wild type strain in vitro, the mutant remains avirulent on both immature pea...

76 FR 189 - Notice of Availability of the Models for Plant-Specific Adoption of Technical Specifications Task...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-03

... Specifications (STS) to define a new time limit for restoring inoperable RCS leakage detection instrumentation to... operability of the RCS leakage detection instrumentation. The CLIIP model SE will facilitate expedited... Operability Requirements and Actions for RCS Leakage Instrumentation'' AGENCY: U.S. Nuclear Regulatory...

75 FR 18907 - Notice of Opportunity for Public Comment on the Proposed Model Safety Evaluation for Plant...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-13

... Specifications (STS) to define a new time limit for restoring inoperable RCS leakage detection instrumentation to... contents of the facility design bases related to the operability of the RCS leakage detection... leakage detection instrumentation to operable status and establish alternate methods of monitoring RCS...

JF-104 ground testing reaction control system (RCS) jets

NASA Technical Reports Server (NTRS)

1961-01-01

JF-104A (formerly YF-104A, serial # 55-2961) was modifed with a hydrogen peroxide reaction control system (RCS). Following a zoom climb to altitudes in the vicinity of 80,000 feet, the RCS system gave the aircraft controllability in the thin upper atmosphere where conventional control surfaces are ineffective.

Multistress Regulation in Escherichia coli: Expression of osmB Involves Two Independent Promoters Responding either to σS or to the RcsCDB His-Asp Phosphorelay

PubMed Central

Boulanger, Alice; Francez-Charlot, Anne; Conter, Annie; Castanié-Cornet, Marie-Pierre; Cam, Kaymeuang; Gutierrez, Claude

2005-01-01

Transcription of the Escherichia coli osmB gene is induced by several stress conditions. osmB is expressed from two promoters, osmBp1 and osmBp2. The downstream promoter, osmBp2, is induced after osmotic shock or upon entry into stationary phase in a σS-dependent manner. The upstream promoter, osmBp1, is independent of σS and is activated by RcsB, the response regulator of the His-Asp phosphorelay signal transduction system RcsCDB. RcsB is responsible for the induction of osmBp1 following treatment with chlorpromazine. Activation of osmBp1 by RcsB requires a sequence upstream of its −35 element similar to the RcsB binding site consensus, suggesting a direct regulatory role. osmB appears as another example of a multistress-responsive gene whose transcription involves both a σS-dependent promoter and a second one independent of σS but controlled by stress-specific transcription factors. PMID:15838058

Automatic detection and measurement of viral replication compartments by ellipse adjustment

PubMed Central

Garcés, Yasel; Guerrero, Adán; Hidalgo, Paloma; López, Raul Eduardo; Wood, Christopher D.; Gonzalez, Ramón A.; Rendón-Mancha, Juan Manuel

2016-01-01

Viruses employ a variety of strategies to hijack cellular activities through the orchestrated recruitment of macromolecules to specific virus-induced cellular micro-environments. Adenoviruses (Ad) and other DNA viruses induce extensive reorganization of the cell nucleus and formation of nuclear Replication Compartments (RCs), where the viral genome is replicated and expressed. In this work an automatic algorithm designed for detection and segmentation of RCs using ellipses is presented. Unlike algorithms available in the literature, this approach is deterministic, automatic, and can adjust multiple RCs using ellipses. The proposed algorithm is non iterative, computationally efficient and is invariant to affine transformations. The method was validated over both synthetic images and more than 400 real images of Ad-infected cells at various timepoints of the viral replication cycle obtaining relevant information about the biogenesis of adenoviral RCs. As proof of concept the algorithm was then used to quantitatively compare RCs in cells infected with the adenovirus wild type or an adenovirus mutant that is null for expression of a viral protein that is known to affect activities associated with RCs that result in deficient viral progeny production. PMID:27819325

Automatic detection and measurement of viral replication compartments by ellipse adjustment

NASA Astrophysics Data System (ADS)

Garcés, Yasel; Guerrero, Adán; Hidalgo, Paloma; López, Raul Eduardo; Wood, Christopher D.; Gonzalez, Ramón A.; Rendón-Mancha, Juan Manuel

2016-11-01

Viruses employ a variety of strategies to hijack cellular activities through the orchestrated recruitment of macromolecules to specific virus-induced cellular micro-environments. Adenoviruses (Ad) and other DNA viruses induce extensive reorganization of the cell nucleus and formation of nuclear Replication Compartments (RCs), where the viral genome is replicated and expressed. In this work an automatic algorithm designed for detection and segmentation of RCs using ellipses is presented. Unlike algorithms available in the literature, this approach is deterministic, automatic, and can adjust multiple RCs using ellipses. The proposed algorithm is non iterative, computationally efficient and is invariant to affine transformations. The method was validated over both synthetic images and more than 400 real images of Ad-infected cells at various timepoints of the viral replication cycle obtaining relevant information about the biogenesis of adenoviral RCs. As proof of concept the algorithm was then used to quantitatively compare RCs in cells infected with the adenovirus wild type or an adenovirus mutant that is null for expression of a viral protein that is known to affect activities associated with RCs that result in deficient viral progeny production.

Metabolite profiling of RCS-4, a novel synthetic cannabinoid designer drug, using human hepatocyte metabolism and TOF-MS

PubMed Central

Gandhi, Adarsh S; Zhu, Mingshe; Pang, Shaokun; Wohlfarth, Ariane; Scheidweiler, Karl B; Huestis, Marilyn A

2014-01-01

Background Since 2009, scheduling legislation of synthetic cannabinoids prompted new compound emergence to circumvent legal restrictions. 2-(4-methoxyphenyl)-1-(1-pentyl-indol-3-yl)methanone (RCS-4) is a potent cannabinoid receptor agonist sold in herbal smoking blends. Absence of parent synthetic cannabinoids in urine suggests the importance of metabolite identification for detecting RCS-4 consumption in clinical and forensic investigations. Materials & methods & Results With 1 h human hepatocyte incubation and TOF high-resolution MS, we identified 18 RCS-4 metabolites, many not yet reported. Most metabolites were hydroxylated with or without demethylation, carboxylation and dealkylation followed by glucuronidation. One additional sulfated metabolite was also observed. O-demethylation was the most common biotransformation and generated the major metabolite. Conclusion For the first time, we present a metabolic scheme of RCS-4 obtained from human hepatocytes, including Phase I and II metabolites. Metabolite structural information and associated high-resolution mass spectra can be employed for developing clinical and forensic laboratory RCS-4 urine screening methods. PMID:25046048

Thermographic Inspections And The Residential Conservation Service Program (RCS)

NASA Astrophysics Data System (ADS)

Ward, Ronald J.

1983-03-01

Rhode Islanders Saving Energy (RISE) is a non-profit corporation founded in 1977 to provide Rhode Island residents with a variety of energy conservation services. Since January of 1981, it has been performing energy audits in compliance with the Department of Energy's (DOE) Residential Conservation Service Program (RCS). One aspect of the RCS program is the performance of inspections on energy conservation activities completed according to RCS installation guidelines. This paper will describe both the use and results of thermographic inspections within the RISE program. The primary objective of these inspections has been to assure the quality of the building envelope after completion of retrofit measures. Thermal anamolies have been detected that vary in size, location and probable cause. Approximately 37% of all jobs performed through RISE in conjunction with the RCS program have required remedial work as a result of problems that were identi-fied during the thermographic inspection. This percentage was much higher when infra-red inspections were conducted on "Non-RCS" retrofits. Statistics will be presented that provide an interesting insight on the quality of retrofit work when performed in associa-tion with a constant inspection process.

Adenovirally transduced bone marrow stromal cells differentiate into pigment epithelial cells and induce rescue effects in RCS rats.

PubMed

Arnhold, Stefan; Heiduschka, Peter; Klein, Helmut; Absenger, Yvonne; Basnaoglu, Serkan; Kreppel, Florian; Henke-Fahle, Sylvia; Kochanek, Stefan; Bartz-Schmidt, Karl-Ulrich; Addicks, Klaus; Schraermeyer, Ulrich

2006-09-01

To determine the potential of adenovirally transduced bone marrow stromal cells (BMSCs) to differentiate into retinal pigment epithelial-like cells and to evaluabe possible rescue effects after transplantation into the retinas of Royal College of Surgeons (RCS) rats. Through a high-capacity adenoviral vector expressing either green fluorescent protein (GFP) or pigment epithelial-derived factor (PEDF), rat MSCs were transduced in vitro before subretinal transplantation into Wistar rats or, alternatively, RCS rats. Two months after cell injection, the rats were killed and the eyes enucleated. The eyes were then investigated light microscopically or processed for electron microscopic investigations. Cell differentiation and integration were analyzed immunocytochemically using antibodies against cytokeratin and the tight junction protein ZO-1. Electroretinography was performed 16 days after injection of cells, to check whether a functional rescue could be detected. In vitro experiments in cocultured human MSCs and human RPE cells showed that MSCs adopted RPE-like characteristics. In grafting experiments, some rat MSCs integrate into the host RPE cell layer of Wistar and RCS rats, indicated by their hexagonal morphology. Subretinally transplanted cells express the epithelial marker cytokeratin and establish tight junctions with the host RPE cells. Furthermore, rescue effects can be demonstrated after grafting of vector-transduced and nontransduced MSCs in semithin sections of dystrophic retinas. Ultrastructurally, MSCs can be detected on top of host RPE and in close contact with photoreceptor outer segments phagocytosing rod outer segments. Taken together, these results raise the possibility that MSCs have the potency to replace diseased RPE cells and deliver therapeutic proteins into the subretinal space to protect photoreceptor cells from degeneration.

BEAM TRANSPORT LINES FOR THE BSNS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

WEI, J.

2006-06-26

This paper presents the design of two beam transport lines at the BSNS: one is the injection line from the Linac to the RCS and the other is the target line from the RCS to the target station. In the injection beam line, space charge effects, transverse halo collimation, momentum tail collimation and debunching are the main concerned topics. A new method of using triplet cells and stripping foils is used to collimate transverse halo. A long straight section is reserved for the future upgrading linac and debuncher. In the target beam line, large halo emittance, beam stability at themore » target due to kicker failures and beam jitters, shielding of back-scattering neutrons from the target are main concerned topics. Special bi-gap magnets will be used to reduce beam losses in the collimators in front of the target.« less

Material Properties of a Tricalcium Silicate-containing, a Mineral Trioxide Aggregate-containing, and an Epoxy Resin-based Root Canal Sealer.

PubMed

Prüllage, Raquel-Kathrin; Urban, Kent; Schäfer, Edgar; Dammaschke, Till

2016-12-01

The aim was to compare the solubility, radiopacity, and setting times of a tricalcium silicate-containing (BioRoot RCS; Septodont, St Maur-des-Fossés, France) and a mineral trioxide aggregate-containing sealer (MTA Fillapex; Angelus, Londrina, Brazil) with an epoxy resin-based sealer (AH Plus; Dentsply DeTrey, Konstanz, Germany). Solubility in distilled water, radiopacity, and setting time were evaluated in accordance with ISO 6876:2012. The solubility was also measured after soaking the materials in phosphate-buffered saline buffer (PBS). All data were analyzed using 1-way analysis of variance and the Student-Newman-Keuls test. After immersion for 1 minute in distilled water, BioRoot RCS was significantly less soluble than AH Plus and MTA Fillapex (P < .05). At all other exposure times, AH Plus was significantly less soluble than BioRoot RCS, whereas BioRoot RCS was significantly more soluble than the other 2 sealers (P < .05). All sealers had the same solubility in PBS and distilled water, except for BioRoot RCS after 28 days. At this exposure time, BioRoot RCS was significantly less soluble in PBS than in distilled water and less soluble than MTA Fillapex (P < .05). All BioRoot RCS specimens immersed in PBS had a surface precipitate after 14 and 28 days. The radiopacity of all sealers was greater than 3 mm aluminum with no statistical significant difference between the sealers (P > .05). The final setting time was 324 (±1) minutes for BioRoot RCS and 612 (±4) minutes for AH Plus. The difference was statistically significant (P < .05). MTA Fillapex did not set completely even after 1 week. The solubility and radiopacity of the sealers were in accordance with ISO 6876:2012. PBS decreased the solubility of BioRoot RCS. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Non-Toxic Reaction Control System for the Reusable First Stage Vehicle

NASA Technical Reports Server (NTRS)

Keith, E. L.; Rothschild, W. J.

1999-01-01

This paper presents the Boeing Reusable Space Systems vision of a Reaction Control System (RCS) for the Reusable First Stage (RFS) being considered as a replacement for the Solid Rocket Booster for the Space Shuttle. The requirement is to achieve reliable vehicle control during the upper atmospheric portion of the RFS trajectory while enabling more efficient ground operations, unhindered by constraints caused by operating with highly toxic RCS propellants. Boeing's objective for this effort is to develop a safer, more efficient and environmentally friendly RCS design approach that is suitable for the RFS concept of operations, including a low cost, efficient turnaround cycle. The Boeing RCS concept utilizes ethanol and liquid oxygen in place of the highly toxic, suspected carcinogen, ozone-depleting mono-methyl-hydrazine and highly toxic nitrogen tetroxide. The Space Shuttle Upgrade program, under the leadership of the NASA Johnson Space Flight Center, is currently developing liquid oxygen and ethanol (ethyl alcohol) technology for use as non-toxic orbital maneuvering system (OMS) and RCS. The development of this liquid oxygen and ethanol technology for the Space Shuttle offers a significant leverage to select much of the same technology for the RFS program. There are significant design and development issues involved with bringing this liquid oxygen and ethanol technology to a state of maturity suitable for an operational RCS. The risks associated with a new LOX and Ethanol RCS are mitigated by maintaining kerosene and hydrogen peroxide RCS technology as an alternative. These issues, presented within this paper, include managing the oxygen supply and achieving reliable ignition in the short pulse mode of engine operation. Performance, reliability and operations requirements are presented along with a specific RCS design concept to satisfying these requirements. The work reported in this paper was performed under NASA Marshall Space Flight Center Contract Number NAS8-97272 to define Reusable First Stage design concepts for the Space Shuttle.

Non-Toxic Reaction Control System for the Reusable First Stage Vehicle

NASA Technical Reports Server (NTRS)

Keith, E. L.; Rothschild, W. J.

1999-01-01

This paper presents the Boeing Reusable Space Systems vision of a Reaction Control System (RCS) for the Reusable First Stage (RFS) being considered as a replacement for the Solid Rocket Booster for the Space Shuttle. The requirement is to,achieve reliable vehicle control during the upper atmospheric portion of the RFS trajectory while enabling more efficient ground operations, unhindered by constraints caused by operating with highly toxic RCS propellants. Boeing's objective for this effort is to develop a safer, more efficient and environmentally friendly RCS design approach that is suitable for the RFS concept of operations, including a low cost, efficient turnaround cycle. The Boeing RCS concept utilizes ethanol and liquid oxygen in place of the highly toxic, suspected carcinogen, ozone- depleting mono-methyl-hydrazine and highly toxic nitrogen tetroxide. The Space Shuttle Upgrade program, under the leadership of the NASA Johnson Space Flight Center, is currently developing liquid oxygen and ethanol (ethyl alcohol) technology for use as non-toxic orbital maneuvering system (OMS) and RCS. The development of this liquid oxygen and ethanol technology for the Space Shuffle offers a significant leverage to select much of the same technology for the RFS program. There are significant design and development issues involved with bringing this liquid oxygen and ethanol technology to a state of maturity suitable for an operational RCS, The risks associated with a new LOX and Ethanol RCS are mitigated by maintaining kerosene and hydrogen peroxide RCS technology as an alternative. These issues, presented within this paper, include managing the oxygen supply and achieving reliable ignition in the short pulse mode of engine operation. Performance, reliability and operations requirements are presented along with a specific RCS design concept to satisfying these requirements. The work reported in this paper was performed under NASA Marshall Space Flight Center Contract to define Reusable First Stage design concepts for the Space Shuttle.

Activation of mitochondrial calpain and release of apoptosis-inducing factor from mitochondria in RCS rat retinal degeneration.

PubMed

Mizukoshi, Sayuri; Nakazawa, Mitsuru; Sato, Kota; Ozaki, Taku; Metoki, Tomomi; Ishiguro, Sei-ichi

2010-09-01

The present study was performed to investigate changes of cytosolic and mitochondrial calpain activities, and effects of intravitreously injected calpain inhibitor on photoreceptor apoptosis in Royal College of Surgeon's (RCS) rats. Time courses of activities for both cytosolic and mitochondrial calpains and amount of calpastatin in RCS rat retina were analyzed by subcellular fractionation, calpain assay and western blotting. Calpain assay was colorimetrically performed using Suc-LLVY-Glo as substrate. Effects of intravitreously injected calpain inhibitor (ALLN and PD150606) on RCS rat retinal degeneration were analyzed by TUNEL staining. Effects of mitochondrial calpain activity on activation and translocation of apoptosis-inducing factor (AIF) were analyzed by western blotting. Mitochondrial calpain started to be significantly activated at postnatal (p) 28 days in RCS rat retina, whereas cytosolic micro-calpain was activated at p 35 days, although specific activity of mitochondrial calpain was 13% compared to cytosolic micro-calpain. Intravitreously injected ALLN and PD150606 effectively inhibited photoreceptor apoptosis only when injected at p 25 days, but did not inhibit photoreceptor apoptosis when injected at p 32 days. Parts of AIF were truncated/activated by mitochondrial calpains and translocated to the nucleus. These results suggest that 1), calpain presents not only in the cytosolic fraction but also in the mitochondrial fraction in RCS rat retina; 2), mitochondrial calpain is activated earlier than cytosolic calpain during retinal degeneration in RCS rats; 3), photoreceptor apoptosis may be regulated by not only calpain systems but also other mechanisms; 4), mitochondrial calpain may activate AIF to induce apoptosis; and 5), calpain inhibitors may be partially effective to inhibit photoreceptor apoptosis in RCS rats. The present study provides new insights into the molecular basis for photoreceptor apoptosis in RCS rats and the future possibility of new pharmaceutical treatments for retinitis pigmentosa. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Space Shuttle third flight /STS-3/ entry RCS analysis. [Reaction Control System

NASA Technical Reports Server (NTRS)

Scallion, W. I.; Compton, H. R.; Suit, W. T.; Powell, R. W.; Blackstock, T. A.; Bates, B. L.

1983-01-01

Flight data obtained from three Space Transportation System orbiter entries (STS-1, 2, and 3) are processed and analyzed to determine the roll interactions caused by the firing of the entry reaction control system (RCS). Comparisons between the flight-derived parameters and the predicted derivatives without interaction effects are made. The flight-derived RCS Plume flow-field interaction effects are independently deduced by direct integration of the incremental changes in the wing upper surface pressures induced by RCS side thruster firings. The separately obtained interaction effects are compared to the predicted values and the differences are discussed.

[Blue-light induced expression of S-adenosy-L-homocysteine hydrolase-like gene in Mucor amphibiorum RCS1].

PubMed

Gao, Ya; Wang, Shu; Fu, Mingjia; Zhong, Guolin

2013-09-04

To determine blue-light induced expression of S-adenosyl-L-homocysteine hydrolase-like (sahhl) gene in fungus Mucor amphibiorum RCS1. In the random process of PCR, a sequence of 555 bp was obtained from M. amphibiorum RCS1. The 555 bp sequence was labeled with digoxin to prepare the probe for northern hybridization. By northern hybridization, the transcription of sahhl gene was analyzed in M. amphibiorum RCS1 mycelia culture process from darkness to blue light to darkness. Simultaneously real-time PCR method was used to the sahhl gene expression analysis. Compared with the sequence of sahh gene from Homo sapiens, Mus musculus and some fungi species, a high homology of the 555 bp sequence was confirmed. Therefore, the preliminary confirmation has supported that the 555 bp sequence should be sahhl gene from M. amphibiorum RCS1. Under the dark pre-culture in 24 h, a large amounts of transcript of sahhl gene in the mycelia can be detected by northern hybridization and real-time PCR in the condition of 24 h blue light. But a large amounts of transcript of sahhl gene were not found in other detection for the dark pre-culture of 48 h, even though M. amphibiorum RCS1 mycelia were induced by blue light. Blue light can induce the expression of sahhl gene in the vigorous growth of M. amphibiorum RCS1 mycelia.

Oxidative and reductive metabolism of lipid-peroxidation derived carbonyls

PubMed Central

Singh, Mahavir; Kapoor, Aniruddh; Bhatnagar, Aruni

2015-01-01

Extensive research has shown that increased production of reactive oxygen species (ROS) results in tissue injury under a variety of pathological conditions and chronic degenerative diseases. While ROS are highly reactive and can incite significant injury, polyunsaturated lipids in membranes and lipoproteins are their main targets. ROS-triggered lipid peroxidation reactions generate a range of reactive carbonyl species (RCS), and these RCS spread and amplify ROS-related injury. Several RCS generated in oxidizing lipids, such as 4-hydroxy trans-2-nonenal (HNE), 4-oxo-2-(E)-nonenal (ONE), acrolein, malondialdehyde (MDA) and phospholipid aldehydes have been shown to be produced under conditions of oxidative stress and contribute to tissue injury and dysfunction by depleting glutathione and other reductants leading to the modification of proteins, lipids, and DNA. To prevent tissue injury, these RCS are metabolized by several oxidoreductases, including members of the aldo-keto reductase (AKR) superfamily, aldehyde dehydrogenases (ALDHs), and alcohol dehydrogenases (ADHs). Metabolism via these enzymes results in RCS inactivation and detoxification, although under some conditions, it can also lead to the generation of signaling molecules that trigger adaptive responses. Metabolic transformation and detoxification of RCS by oxidoreductases prevent indiscriminate ROS toxicity, while at the same time, preserving ROS signaling. A better understanding of RCS metabolism by oxidoreductases could lead to the development of novel therapeutic interventions to decrease oxidative injury in several disease states and to enhance resistance to ROS-induced toxicity. PMID:25559856

The role of autochthonous organic matter in radioactive cesium accumulation to riverine fine sediments.

PubMed

Fujii, Manabu; Ono, Keisuke; Yoshimura, Chihiro; Miyamoto, Manami

2018-06-15

Anthropogenically released radioactive cesium (RCs) poses serious ecological and environmental concerns given its persistency in the environment. Although accumulation of RCs in aqueous and sedimentary environments is often reported to associate with organic matter (OM), the mechanisms responsible remain unclear. Here, we investigated RCs in fine sediments along the Abukuma River, the largest river near the Fukushima Daiichi Nuclear Power Plant, 1.5-4 years after the accident. Measuring the density-separated sediment fractions with a broad range of OM content (%) indicated that the RCs concentration (Bq·kg -1 ) is positively correlated with OM content for intermediate-density fractions in which OM is primarily characterized by autochthonous origin. This relationship, however, did not hold for light-density fractions containing a high proportion of large-size allochthonous OM. Furthermore, H 2 O 2 -assisted OM digestion and amorphous material dissolution treatments resulted in only a minor reduction in sedimentary RCs. These results along with the fact that sediments with high autochthonous OM content showed high specific surface area indicated that RCs is tightly associated with finer-grained and chemically non-labile inorganic fractions concurrently resident with autochthonous OM. Overall, our findings highlight that autochthonous OM exerts a significant control on the accumulation, transport, and fate of RCs in aqueous and sedimentary environments. Copyright © 2018 Elsevier Ltd. All rights reserved.

Oxygen/Alcohol Dual Thrust RCS Engines

NASA Technical Reports Server (NTRS)

Angstadt, Tara; Hurlbert, Eric

1999-01-01

A non-toxic dual thrust RCS engine offers significant operational, safety, and performance advantages to the space shuttle and the next generation RLVs. In this concept, a single engine produces two thrust levels of 25 and 870 lbf. The low thrust level is provided by the spark torch igniter, which, with the addition of 2 extra valves, can also be made to function as a vernier. A dual thrust RCS engine allows 38 verniers to be packaged more efficiently on a vehicle. These 38 vemiers improve translation and reduce cross coupling, thereby providing more pure roll, pitch, and yaw maneuvers of the vehicle. Compared to the 6 vemiers currently on the shuttle, the 38 dual thrust engines would be 25 to 40% more efficient for the same maneuvers and attitude control. The vernier thrust level also reduces plume impingement and contamination concerns. Redundancy is also improved, thereby improving mission success reliability. Oxygen and ethanol are benign propellants which do not create explosive reaction products or contamination, as compared to hypergolic propellants. These characteristics make dual-thrust engines simpler to implement on a non-toxic reaction control system. Tests at WSTF in August 1999 demonstrated a dual-thrust concept that is successful with oxygen and ethanol. Over a variety of inlet pressures and mixture ratios at 22:1 area ratio, the engine produced between 230 and 297 sec Isp, and thrust levels from 8 lbf. to 50 lbf. This paper describes the benefits of dual-thrust engines and the recent results from tests at WSTF.

Supplementing rumen-protected Met and Lys in alfalfa and red clover silage diets fed to lactating dairy cows

USDA-ARS?s Scientific Manuscript database

The action of polyphenol oxidase reduces NPN formation in red clover silage (RCS). In seven previous trials, RCS averaged (% of total N) 36% NPN vs. 54% NPN in alfalfa silage (AS). Feeding RCS has been found to increase intestinal protein absorption but with no improvement in N utilization, suggesti...

Integration of multiple stimuli-sensing systems to regulate HrpS and type III secretion system in Erwinia amylovora.

PubMed

Lee, Jae Hoon; Zhao, Youfu

2018-02-01

The bacterial enhancer binding protein (bEBP) HrpS is essential for Erwinia amylovora virulence by activating the type III secretion system (T3SS). However, how the hrpS gene is regulated remains poorly understood in E. amylovora. In this study, 5' rapid amplification of cDNA ends and promoter deletion analyses showed that the hrpS gene contains two promoters driven by HrpX/HrpY and the Rcs phosphorelay system, respectively. Electrophoretic mobility shift and gene expression assays demonstrated that integration host factor IHF positively regulates hrpS expression through directly binding the hrpX promoter and positively regulating hrpX/hrpY expression. Moreover, hrpX expression was down-regulated in the relA/spoT ((p)ppGpp-deficient) mutant and the dksA mutant, but up-regulated when the wild-type strain was treated with serine hydroxamate, which induced (p)ppGpp-mediated stringent response. Furthermore, the csrA mutant showed significantly reduced transcripts of major hrpS activators, including the hrpX/hrpY, rcsA and rcsB genes, indicating that CsrA is required for full hrpS expression. On the other hand, the csrB mutant exhibited up-regulation of the rcsA and rcsB genes, and hrpS expression was largely diminished in the csrB/rcsB mutant, indicating that the Rcs system is mainly responsible for the increased hrpS expression in the csrB mutant. These findings suggest that E. amylovora recruits multiple stimuli-sensing systems, including HrpX/HrpY, the Rcs phosphorelay system and the Gac-Csr system, to regulate hrpS and T3SS gene expression.

Purple-bacterial photosynthetic reaction centers and quantum-dot hybrid-assemblies in lecithin liposomes and thin films.

PubMed

Lukashev, Eugeny P; Knox, Petr P; Gorokhov, Vladimir V; Grishanova, Nadezda P; Seifullina, Nuranija Kh; Krikunova, Maria; Lokstein, Heiko; Paschenko, Vladimir Z

2016-11-01

Quantum dots (QDs) absorb ultraviolet and long-wavelength visible light energy much more efficiently than natural bacterial light-harvesting proteins and can transfer the excitation energy to photosynthetic reaction centers (RCs). Inclusion of RCs combined with QDs as antennae into liposomes opens new opportunities for using such hybrid systems as a basis for artificial energy-transforming devices that potentially can operate with greater efficiency and stability than devices based only on biological components or inorganic components alone. RCs from Rhodobacter sphaeroides and QDs (CdSe/ZnS with hydrophilic covering) were embedded in lecithin liposomes by extrusion of a solution of multilayer lipid vesicles through a polycarbonate membrane or by dialysis of lipids and proteins dispersed with excess detergent. The efficiency of RC and QD interaction within the liposomes was estimated using fluorescence excitation spectra of the photoactive bacteriochlorophyll of the RCs and by measuring the fluorescence decay kinetics of the QDs. The functional activity of the RCs in hybrid complexes was fully maintained, and their stability was even increased. The efficiency of energy transfer between QDs and RCs and conditions of long-term stability of function of such hybrid complexes in film preparations were investigated as well. It was found that dry films containing RCs and QDs, maintained at atmospheric humidity, are capable of maintaining their functional activity for at least some months as judged by measurements of their spectral characteristics, efficiency of energy transfer from QDs to RCs and RC electron transport activity. Addition of trehalose to the films increases the stability further, especially for films maintained at low humidity. These stable hybrid film structures are promising for further studies towards developing new phototransformation devices for biotechnological applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Novel Mechanism for Scavenging of Hypochlorite Involving a Periplasmic Methionine-Rich Peptide and Methionine Sulfoxide Reductase

PubMed Central

Melnyk, Ryan A.; Youngblut, Matthew D.; Clark, Iain C.; Carlson, Hans K.; Wetmore, Kelly M.; Price, Morgan N.; Iavarone, Anthony T.; Deutschbauer, Adam M.; Arkin, Adam P.

2015-01-01

ABSTRACT Reactive chlorine species (RCS) defense mechanisms are important for bacterial fitness in diverse environments. In addition to the anthropogenic use of RCS in the form of bleach, these compounds are also produced naturally through photochemical reactions of natural organic matter and in vivo by the mammalian immune system in response to invading microorganisms. To gain insight into bacterial RCS defense mechanisms, we investigated Azospira suillum strain PS, which produces periplasmic RCS as an intermediate of perchlorate respiration. Our studies identified an RCS response involving an RCS stress-sensing sigma/anti-sigma factor system (SigF/NrsF), a soluble hypochlorite-scavenging methionine-rich periplasmic protein (MrpX), and a putative periplasmic methionine sulfoxide reductase (YedY1). We investigated the underlying mechanism by phenotypic characterization of appropriate gene deletions, chemogenomic profiling of barcoded transposon pools, transcriptome sequencing, and biochemical assessment of methionine oxidation. Our results demonstrated that SigF was specifically activated by RCS and initiated the transcription of a small regulon centering around yedY1 and mrpX. A yedY1 paralog (yedY2) was found to have a similar fitness to yedY1 despite not being regulated by SigF. Markerless deletions of yedY2 confirmed its synergy with the SigF regulon. MrpX was strongly induced and rapidly oxidized by RCS, especially hypochlorite. Our results suggest a mechanism involving hypochlorite scavenging by sacrificial oxidation of the MrpX in the periplasm. Reduced MrpX is regenerated by the YedY methionine sulfoxide reductase activity. The phylogenomic distribution of this system revealed conservation in several Proteobacteria of clinical importance, including uropathogenic Escherichia coli and Brucella spp., implying a putative role in immune response evasion in vivo. PMID:25968643

Accelerated removal of antibody-coated red blood cells from the circulation is accurately tracked by a biotin label

PubMed Central

Mock, Donald M.; Lankford, Gary L.; Matthews, Nell I.; Burmeister, Leon F.; Kahn, Daniel; Widness, John A.; Strauss, Ronald G.

2013-01-01

BACKGROUND Safe, accurate methods to reliably measure circulating red blood cell (RBC) kinetics are critical tools to investigate pathophysiology and therapy of anemia, including hemolytic anemias. This study documents the ability of a method using biotin-labeled RBCs (BioRBCs) to measure RBC survival (RCS) shortened by coating with a highly purified monomeric immunoglobulin G antibody to D antigen. STUDY DESIGN AND METHODS Autologous RBCs from 10 healthy D+ subjects were labeled with either biotin or 51Cr (reference method), coated (opsonized) either lightly (n = 4) or heavily (n = 6) with anti-D, and transfused. RCS was determined for BioRBCs and for 51Cr independently as assessed by three variables: 1) posttransfusion recovery at 24 hours (PTR24) for short-term RCS; 2) time to 50% decrease of the label (T50), and 3) mean potential life span (MPL) for long-term RCS. RESULTS BioRBCs tracked both normal and shortened RCS accurately relative to 51Cr. For lightly coated RBCs, mean PTR24, T50, and MPL results were not different between BioRBCs and 51Cr. For heavily coated RBCs, both short-term and long-term RCS were shortened by approximately 17 and 50%, respectively. Mean PTR24 by BioRBCs (84 ± 18%) was not different from 51Cr (81 ± 10%); mean T50 by BioRBCs (23 ± 17 days) was not different from 51Cr (22 ± 18 days). CONCLUSION RCS shortened by coating with anti-D can be accurately measured by BioRBCs. We speculate that BioRBCs will be useful for studying RCS in conditions involving accelerated removal of RBCs including allo- and autoimmune hemolytic anemias. PMID:22023312

Regeneration of cervical reserve cell-like cells from human induced pluripotent stem cells (iPSCs): A new approach to finding targets for cervical cancer stem cell treatment.

PubMed

Sato, Masakazu; Kawana, Kei; Adachi, Katsuyuki; Fujimoto, Asaha; Yoshida, Mitsuyo; Nakamura, Hiroe; Nishida, Haruka; Inoue, Tomoko; Taguchi, Ayumi; Ogishima, Juri; Eguchi, Satoko; Yamashita, Aki; Tomio, Kensuke; Wada-Hiraike, Osamu; Oda, Katsutoshi; Nagamatsu, Takeshi; Osuga, Yutaka; Fujii, Tomoyuki

2017-06-20

Cervical reserve cells are epithelial progenitor cells that are pathologically evident as the origin of cervical cancer. Thus, investigating the characteristics of cervical reserve cells could yield insight into the features of cervical cancer stem cells (CSCs). In this study, we established a method for the regeneration of cervical reserve cell-like properties from human induced pluripotent stem cells (iPSCs) and named these cells induced reserve cell-like cells (iRCs). Approximately 70% of iRCs were positive for the reserve cell markers p63, CK5 and CK8. iRCs also expressed the SC junction markers CK7, AGR2, CD63, MMP7 and GDA. While iRCs expressed neither ERα nor ERβ, they expressed CA125. These data indicated that iRCs possessed characteristics of cervical epithelial progenitor cells. iRCs secreted higher levels of several inflammatory cytokines such as macrophage migration inhibitory factor (MIF), soluble intercellular adhesion molecule 1 (sICAM-1) and C-X-C motif ligand 10 (CXCL-10) compared with normal cervical epithelial cells. iRCs also expressed human leukocyte antigen-G (HLA-G), which is an important cell-surface antigen for immune tolerance and carcinogenesis. Together with the fact that cervical CSCs can originate from reserve cells, our data suggested that iRCs were potent immune modulators that might favor cervical cancer cell survival. In conclusion, by generating reserve cell-like properties from iPSCs, we provide a new approach that may yield new insight into cervical cancer stem cells and help find new oncogenic targets.

Expression of nitric oxide synthase during the development of RCS rat retinas.

PubMed

Sharma, R K; Warfvinge, K; Ehinger, B

2001-01-01

Nitric oxide (NO) has been reported to be both neurodestructive and neuroprotective in the central nervous system and could possibly play an important role in neurodegenerative disorders. On the assumption that NO synthesis may influence degenerative processes in the retina, we have examined the development and distribution of nitric-oxide-synthase(NOS)-immunoreactive cells in developing Royal College of Surgeons (RCS) rat retinas, which is an animal model for retinal degeneration. An antibody against constitutive neuronal NOS was used for immunocytochemistry on RCS rat retinas from postnatal (PN) days 3, 7, 10, 14, 35, 70 and 281 and compared with that in the normal rats of PN days 3, 7, 10, 14, 54 and adults. Immunoreactive cells were not seen in PN 3 retinas but were distinctly seen in the PN 7 retina along with a plexus in the inner plexiform layer. In both groups (normal and RCS rats) a distinct sublayering of the plexus in the inner plexiform layer could be seen at PN 10, which became more distinct at PN 14. The immunoreactive cells were detected also in the oldest retina examined, which was PN 281 in the case of RCS rats. In both groups, certain amacrine cells, certain bipolar cells and certain horizontal cells were found to be immunoreactive. In conclusion, the developmental timetable of the NOS immunoreactivity was identical in the normal and the RCS rat retinas. The NOS-immunoreactive cells persisted in the RCS retinas even when the retina had degenerated extensively. Abnormalities with the inducible isoforms of NOS cannot be ruled out from this study. We conclude that the chronological and qualitative development of the constitutive neuronal NOS immunoreactivity is normal in RCS rat retinas. Copyright 2001 S. Karger AG, Basel

Frontal cortex and hippocampus neurotransmitter receptor complex level parallels spatial memory performance in the radial arm maze.

PubMed

Shanmugasundaram, Bharanidharan; Sase, Ajinkya; Miklosi, András G; Sialana, Fernando J; Subramaniyan, Saraswathi; Aher, Yogesh D; Gröger, Marion; Höger, Harald; Bennett, Keiryn L; Lubec, Gert

2015-08-01

Several neurotransmitter receptors have been proposed to be involved in memory formation. However, information on receptor complexes (RCs) in the radial arm maze (RAM) is missing. It was therefore the aim of this study to determine major neurotransmitter RCs levels that are modulated by RAM training because receptors are known to work in homo-or heteromeric assemblies. Immediate early gene Arc expression was determined by immunohistochemistry to show if prefrontal cortices (PFC) and hippocampi were activated following RAM training as these regions are known to be mainly implicated in spatial memory. Twelve rats per group, trained and untrained in the twelve arm RAM were used, frontal cortices and hippocampi were taken, RCs in membrane protein were quantified by blue-native PAGE immunoblotting. RCs components were characterised by co-immunoprecipitation followed by mass spectrometrical analysis and by the use of the proximity ligation assay. Arc expression was significantly higher in PFC of trained as compared to untrained rats whereas it was comparable in hippocampi. Frontal cortical levels of RCs containing AMPA receptors GluA1, GluA2, NMDA receptors GluN1 and GluN2A, dopamine receptor D1, acetylcholine nicotinic receptor alpha 7 (nAChR-α7) and hippocampal levels of RCs containing D1, GluN1, GluN2B and nAChR-α7 were increased in the trained group; phosphorylated dopamine transporter levels were decreased in the trained group. D1 and GluN1 receptors were shown to be in the same complex. Taken together, distinct RCs were paralleling performance in the RAM which is relevant for interpretation of previous and design of future work on RCs in memory studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of reaction control system jet-flow field interactions on a 0.015 scale model space shuttle orbiter aerodynamic characteristics

NASA Technical Reports Server (NTRS)

Monta, W. J.; Rausch, J. R.

1973-01-01

The effects of the reaction control system (RCS) jet-flow field interactions on the space shuttle orbiter system during entry are discussed. The primary objective of the test program was to obtain data for the shuttle orbiter configuration to determine control amplification factors resulting from jet interaction between the RCS plumes and the external flow over the vehicle. A secondary objective was to provide data for comparison and improvement of analytic jet interaction prediction techniques. The test program was divided into two phases; (1) force and moment measurements were made with and without RCS blowing, investigating environment parameters (R sub e, Alpha, Beta), RCS plume parameters (Jet pressure ratio, momentum ratio and thrust level), and geometry parameters (RCS pod locations) on the orbiter model, (2) oil flow visualization tests were conducted on a dummy balance at the end of the test.

Preliminary input to the space shuttle reaction control subsystem failure detection and identification software requirements (uncontrolled)

NASA Technical Reports Server (NTRS)

Bergmann, E.

1976-01-01

The current baseline method and software implementation of the space shuttle reaction control subsystem failure detection and identification (RCS FDI) system is presented. This algorithm is recommended for conclusion in the redundancy management (RM) module of the space shuttle guidance, navigation, and control system. Supporting software is presented, and recommended for inclusion in the system management (SM) and display and control (D&C) systems. RCS FDI uses data from sensors in the jets, in the manifold isolation valves, and in the RCS fuel and oxidizer storage tanks. A list of jet failures and fuel imbalance warnings is generated for use by the jet selection algorithm of the on-orbit and entry flight control systems, and to inform the crew and ground controllers of RCS failure status. Manifold isolation valve close commands are generated in the event of failed on or leaking jets to prevent loss of large quantities of RCS fuel.

Segregation of genes from donor strain during the production of recombinant congenic strains.

PubMed

van Zutphen, L F; Den Bieman, M; Lankhorst, A; Demant, P

1991-07-01

Recombinant congenic strains (RCS) constitute a set of inbred strains which are designed to dissect the genetic control of multigenic traits, such as tumour susceptibility or disease resistance. Each RCS contains a small fraction of the genome of a common donor strain, while the majority of genes stem from a common background strain. We tested at two stages of the inbreeding process in 20 RCS, derived from BALB/cHeA and STS/A, to see whether alleles from the STS/A donor strain are distributed over the RCS in a ratio as would theoretically be expected. Four marker genes (Pep-3; Pgm-1; Gpi-1 and Es-3) located at 4 different chromosomes were selected and the allelic distribution was tested after 3-4 and after 12 generations of inbreeding. The data obtained do not significantly deviate from the expected pattern, thus supporting the validity of the concept of RCS.

Modeling the Meteoroid Input Function at Mid-Latitude Using Meteor Observations by the MU Radar

NASA Technical Reports Server (NTRS)

Pifko, Steven; Janches, Diego; Close, Sigrid; Sparks, Jonathan; Nakamura, Takuji; Nesvorny, David

2012-01-01

The Meteoroid Input Function (MIF) model has been developed with the purpose of understanding the temporal and spatial variability of the meteoroid impact in the atmosphere. This model includes the assessment of potential observational biases, namely through the use of empirical measurements to characterize the minimum detectable radar cross-section (RCS) for the particular High Power Large Aperture (HPLA) radar utilized. This RCS sensitivity threshold allows for the characterization of the radar system s ability to detect particles at a given mass and velocity. The MIF has been shown to accurately predict the meteor detection rate of several HPLA radar systems, including the Arecibo Observatory (AO) and the Poker Flat Incoherent Scatter Radar (PFISR), as well as the seasonal and diurnal variations of the meteor flux at various geographic locations. In this paper, the MIF model is used to predict several properties of the meteors observed by the Middle and Upper atmosphere (MU) radar, including the distributions of meteor areal density, speed, and radiant location. This study offers new insight into the accuracy of the MIF, as it addresses the ability of the model to predict meteor observations at middle geographic latitudes and for a radar operating frequency in the low VHF band. Furthermore, the interferometry capability of the MU radar allows for the assessment of the model s ability to capture information about the fundamental input parameters of meteoroid source and speed. This paper demonstrates that the MIF is applicable to a wide range of HPLA radar instruments and increases the confidence of using the MIF as a global model, and it shows that the model accurately considers the speed and sporadic source distributions for the portion of the meteoroid population observable by MU.

Analysis of the Radar Reflectivity of Aircraft Vortex Wakes

NASA Technical Reports Server (NTRS)

Shariff, Karim; Wray, Alan; Yan, Jerry (Technical Monitor)

2000-01-01

Radar has been proposed as a way to track wake vortices to reduce aircraft spacing and tests have revealed radar echoes from aircraft wakes in clear air. The results are always interpreted qualitatively using Tatarski's theory of weak scattering by isotropic atmospheric turbulence. The goal of the present work was to predict the value of the radar cross-section (RCS) using simpler models. This is accomplished in two steps. First, the refractive index is obtained. Since the structure of the aircraft wakes is different from atmospheric turbulence, three simple mechanisms specific to vortex wakes are considered: (1) Radial density gradient in a two-dimensional vortex, (2) three-dimensional fluctuations in the vortex cores, and (3) Adiabatic transport of the atmospheric fluid in a two-dimensional oval surrounding the pair of vortices. The index of refraction is obtained more precisely for the two-dimensional mechanisms than for the three-dimensional ones. In the second step, knowing the index of refraction, a scattering analysis is performed. Tatarski's weak scattering approximation is kept but the usual assumptions of a far-field and a uniform incident wave are dropped. Neither assumption is generally valid for a wake that is coherent across the radar beam. For analytical insight, a simpler approximation that invokes, in addition to weak scattering, the far-field and wide cylindrical beam assumptions, is also developed and compared with the more general analysis. The predicted RCS values for the oval surround the vortices (mechanism C) agree with the experiments of Bilson conducted over a wide range of frequencies. However, the predictions have a cut-off away from normal incidence which is not present in the measurements. Estimates suggest that this is due to turbulence in the baroclinic vorticity generated at the boundary of the oval. The reflectivity of a vortex itself (mechanism A) is comparable to that of the oval (mechanism C) but cuts-off at frequencies lower than those considered in all the experiments to date. The RCS of a vortex happens to peak at the frequency (about 49 MHz) where atmospheric radars (known as ST radars) operate and so the present prediction could be verified in the future. Finally , we suggest that hot engine exhaust could increase RCE by 40 db and reveal vortex circulation, provided its mixing with the surroundings is prevented in the laminarising flow of the vortices.

Command module/service module reaction control subsystem assessment

NASA Technical Reports Server (NTRS)

Weary, D. P.

1971-01-01

Detailed review of component failure histories, qualification adequacy, manufacturing flow, checkout requirements and flow, ground support equipment interfaces, subsystem interface verification, protective devices, and component design did not reveal major weaknesses in the command service module (CSM) reaction control system (RCS). No changes to the CSM RCS were recommended. The assessment reaffirmed the adequacy of the CSM RCS for future Apollo missions.

Disseminating the Right Information to the Right Audience: Cultural Determinants in the Use (and Misuse) of Rankings

ERIC Educational Resources Information Center

Cremonini, Leon; Westerheijden, Don; Enders, Jurgen

2008-01-01

Rankings and league tables, or Report Cards (RCs), of Higher Education Institutions have become a global phenomenon. Their purpose, it is claimed, is to help "student-consumers" make informed decisions. Yet the degree to which RCs succeed in helping students in their college choice is disputed. Even though RCs are intended for all, which…

The optical/ultraviolet excess of isolated neutron stars in the resonant cyclotron scattering model

NASA Astrophysics Data System (ADS)

Tong, Hao; Xu, Ren-Xin; Song, Li-Ming

2011-12-01

X-ray dim isolated neutron stars are peculiar pulsar-like objects, characterized by their Planck-like spectrum. In studying their spectral energy distributions, optical/ultraviolet (UV) excess is a long standing problem. Recently Kaplan et al. measured the optical/UV excess for all seven sources, which is understandable in the resonant cyclotron scattering (RCS) model previously addressed. The RCS model calculations show that the RCS process can account for the observed optical/UV excess for most sources. The flat spectrum of RX J2143.0+0654 may be due to contributions from the bremsstrahlung emission of the electron system in addition to the RCS process.

Resolving the problem of compliance with the ever increasing and changing regulations

NASA Astrophysics Data System (ADS)

Leigh, Harley

1992-01-01

The most common problem identified at several U.S. Department of Energy (DOE) sites is regulatory compliance. Simply, the project viability depends on identifying regulatory requirements at the beginning of a specific project to avoid possible delays and cost overruns. The Radioisotope Power Systems Facility (RPSF) is using the Regulatory Compliance System (RCS) to deal with the problem that well over 1000 regulatory documents had to be reviewed for possible compliance requirements applicable to the facility. This overwhelming number of possible documents is not atypical of all DOE facilities thus far reviewed using the RCS system. The RCS was developed to provide control and tracking of all the regulatory and institutional requirements on a given project. WASTREN, Inc., developed the RCS through various DOE contracts and continues to enhance and update the system for existing and new contracts. The RCS provides the information to allow the technical expert to assimilate and manage accurate resource information, compile the necessary checklists, and document that the project or facility fulfills all of the appropriate regulatory requirements. The RCS provides on-line information, including status throughout the project life, thereby allowing more intelligent and proactive decision making. Also, consistency and traceability are provided for regulatory compliance documentation.

Heparanase expression in periapical granulomas and radicular cysts.

PubMed

Elad, S; Sherman, Y; Palmon, A; Vlodavsky, I; Or, R

2013-01-01

Heparanase is an endo-β-D-glucuronidase enzyme which degrades heparan sulfate glycosaminoglycan side chains of proteoglycans in the extracellular matrix and in basement membranes. The aim of this study was to evaluate the expression of heparanase in periapical granulomas (PGs) and radicular cysts (RCs). Immunohistochemistry was used to assess heparanase expression in PGs and RCs. Parameters including stain intensity, location and cell type were used to characterize heparanase expression in the periapical lesions. Ordered categories (from weak to strong) were used to compare the level of heparanase staining in the PG and RC groups. Both epithelial cells and inflammatory cells were positive for heparanase. The relative staining of the epithelial cells was strong, whereas the relative staining of the inflammatory cells was weak. Significant differences in immunohistochemical staining of epithelial cells were observed between RCs and PGs (p = 0.002). The relative expression of heparanase in epithelial cells in RCs was strong. In PGs, lesions with few or no epithelial cells, heparanase was predominantly expressed weakly by inflammatory cells. PGs and RCs have the same infectious origin. Therefore, the different cellular sources of heparanase in these periapical lesions may imply that this enzyme has specific pathogenetic functions in RCs and PGs.

The Quantitative Reasoning for College Science (QuaRCS) Assessment in non-Astro 101 Courses

NASA Astrophysics Data System (ADS)

Kirkman, Thomas W.; Jensen, Ellen

2016-06-01

The innumeracy of American students and adults is a much lamented educational problem. The quantitative reasoning skills of college students may be particularly addressed and improved in "general education" science courses like Astro 101. Demonstrating improvement requires a standardized instrument. Among the non-proprietary instruments the Quantitative Literacy and Reasoning Assessment[1] (QRLA) and the Quantitative Reasoning for College Science (QuaRCS) Assessment[2] stand out.Follette et al. developed the QuaRCS in the context of Astro 101 at University of Arizona. We report on QuaRCS results in different contexts: pre-med physics and pre-nursing microbiology at a liberal arts college. We report on the mismatch between students' contemporaneous report of a question's difficulty and the actual probability of success. We report correlations between QuaRCS and other assessments of overall student performance in the class. We report differences in attitude towards mathematics in these two different but health-related student populations .[1] QLRA, Gaze et al., 2014, DOI: http://dx.doi.org/10.5038/1936-4660.7.2.4[2] QuaRCS, Follette, et al., 2015, DOI: http://dx.doi.org/10.5038/1936-4660.8.2.2

Temporal and spatial characteristics of cone degeneration in RCS rats.

PubMed

Huang, Yan Ming; Yin, Zheng Qin; Liu, Kang; Huo, Shu Jia

2011-03-01

The temporal and spatial characteristics of cone degeneration in the Royal College of Surgeons (RCS) rat were studied to provide information for treatment strategies of retinitis pigmentosa. Nonpigmented dystrophic RCS rats (RCS) and pigmented nondystrophic RCS rats (controls) were used. Cone processes were visualized with peanut agglutinin (PNA). Cone development appears to have been completed by postnatal day 21 (P21) in both the RCS and control rats. Signs of cone degeneration were obvious by P30, with shorter outer segments (OSs) and enlarged inner segments (ISs). At that time, 81.7% of the cones retained stained ISs. The rate of IS density decline was slower in the peripheral, nasal, and superior retina, and only 43.6% of the cones with ISs were present at P45. By P60, PNA-labeled cone ISs were distorted and restricted to the peripheral retina, and by P90, few cone pedicles were detected. Our findings indicate that therapeutic strategies aimed at rescuing cones in the degenerating retina should be applied before P21 and no later than P45 while substantial numbers of cones retain their ISs. Either the middle or peripheral regions of the nasal and superior retina are the best locations for transplantation strategies.

Low-Cost Cold-Gas RCS for the Sloshsat Small Satellite

NASA Astrophysics Data System (ADS)

Adler, S.; Warshavsky, A.; Peretz, A.

2002-01-01

Cold gas thrusters usually provide an inexpensive, highly reliable, low-power consuming, non contaminating, and safe auxiliary propulsion means for small spacecraft. A low-cost cold-gas Reaction Control System (RCS) has been designed and developed to provide linear acceleration and rotation control of the SLOSHSAT satellite for liquid-slosh experimentation. This ESA-sponsored mini-spacecraft will be launched by the Space Shuttle and ejected into space from its hitchhiker bay. The RCS was designed and developed according to man rated safety standards, as required by NASA. The RCS comprises four identical spherical carbon/epoxy-wound stainless steel tanks, which store 1.6 kg of nitrogen at 600 bars, corresponding to a maximum rated temperature of 70°C. The relatively high pressure enables economic utilization of the limited space available in small satellites. The tanks are of a "leak before burst" design, which was subjected to a comprehensive finite-element stress analysis. They were developed and tested in accordance with MIL-STD-1522A, with a proof pressure and a minimum burst pressure of 1000 and 1700 bars, respectively. Each tank has an internal volume of 0.97 l, and is equipped with an attached accessories assembly, that includes a pyrovalve and a filter. The RCS was supplied with the tanks prepressurized and sealed to 473 bars (at 20°C). The whole system is pressurized only after the satellite is in its orbit, by activating the tank's pyrovalve. This unique approach enables to supply a sealed RCS system and propellant loading activities are not necessary before launch. Additionally, this approach has safety advantages that were meaningful to meet the NASA safety requirements. The pyrovalve includes a RAFAEL-developed initiator, which complies with MIL-STD-1576, and passed all required testing, including ESD tests with the resistor removed, as demanded by NASA for approval. The pyrovalve is of a "self seal" design, which includes a sealing mechanism, that seals the system from contamination during the pyrovalve actuation. The test port valve allows proof-pressure and leakage testing of the assembled system. The tanks and their accessories were subjected to extensive qualification testing and met the requirements of a stringent acceptance test procedure. The N2 propellant is supplied to twelve 0.8-N thrusters, at a steady regulated pressure of 15.5 bars. Accurate regulated pressure is obtained by a two stage regulating system, which accepts pressure input range of 600 to 40 bar. The thrusters were especially developed to meet the specific program requirements. They will normally be operated in pairs. For safety reasons and redundancy two relief valves are mounted downstream of the regulators. Each valve can handle the total flow with a minimum pressure rise, which defines the Maximum Operating Pressure (MEOP) in the low-pressure section of the system. The pressure surge phenomenon that follows the pyrovalve actuation was precisely analyzed, and tested in simulated conditions. A surge damper is successfully applied to the gas pipeline, significantly lowering the pressure surge. The sensitivity of the regulated pressure to the pulse modulation of the thrusters was examined. Due to the lock pressure of the regulators, and the difference between the static and dynamic regulated pressure levels, the average pressure was found to depend on the pulse duty cycle. This phenomenon was investigated and a model that predicts the pressure level according to the mass flow rate and pulse modulation was established. A breadboard test system, that completely simulates the pneumatic nature of the SLOSHSAT RCS, was constructed and used for ground test evaluation of the RCS performance in various modes of operation (continuous and pulses of various duty cycles). Computerized data acquisition and data reduction was used for pressure, temperature and mass flow measurements at several locations in the system. The breadboard system was also used for development experiments and investigation of various transient and steady state phenomena to enable successful performance prediction for operation in space. In order to establish appropriate assembly procedures for the RCS in the limited space allocated for it in the SLOSHSAT, a mock-up of the final satellite configuration, an Assembly and Testing System (ATS), was constructed. The complete RCS integrated in the ATS was subjected to vibration tests, followed by proof pressure, leakage and performance tests, as a part of the RCS qualification. All RCS components, except for the thrusters, are off-the-shelf items, adapted for space application by meeting stringent NASA/ESA man-rated mission requirements. A cooperative effort between FOKKER-SPACE and NLR of the Netherlands and RAFAEL of Israel enabled a very efficient RCS architecture that satisfies the limiting volume constraints. This approach made it possible to attain a man-rated, space-qualified cold-gas propulsion system with low-cost and safety and high- reliability attributes.

Manufacturing Methods and Technology (MMT) project execution report

NASA Astrophysics Data System (ADS)

Swim, P. A.

1982-10-01

This document is a summary compilation of the manufacturing methods and technology program project status reports (RCS DRCMT-301) submitted to IBEA from DARCOM major Army subcommands and project managers. Each page of the computerized section lists project number, title, status, funding, and projected completion date. Summary pages give information relating to the overall DARCOM program.

Surveillance of Strontium-90 in Foods after the Fukushima Daiichi Nuclear Power Plant Accident.

PubMed

Nabeshi, Hiromi; Tsutsumi, Tomoaki; Uekusa, Yoshinori; Hachisuka, Akiko; Matsuda, Rieko; Teshima, Reiko

2015-01-01

As a result of the Fukushima Daiichi nuclear power plant (NPP) accident, various radionuclides were released into the environment. In this study, we surveyed strontium-90 ((90)Sr) concentrations in several foodstuffs. Strontium-90 is thought to be the third most important residual radionuclide in food collected after the Fukushima Daiichi, NPP accident after following cesium-137 ((137)Cs) and cesium-134 ((134)Cs). Results of (90)Sr analyses indicated that (90)Sr was detect in 25 of the 40 radioactive cesium (r-Cs) positive samples collected in areas around the Fukushima Daiichi NPP, ranging in distance from 50 to 250 km. R-Cs positive samples were defined as containing both (134)Cs and (137)Cs which are considered to be indicators of the after-effects of the Fukushima Daiichi NPP accident. We also detected (90)Sr in 8 of 13 r-Cs negative samples, in which (134)Cs was not detected. Strontium-90 concentrations in the r-Cs positive samples did not significantly exceed the (90)Sr concentrations in r-Cs negative samples or the (90)Sr concentration ranges in comparable food groups found in previous surveys before the Fukushima Daiichi NPP accident. Thus, (90)Sr concentrations in r-Cs positive samples were indistinguishable from the background (90)Sr concentrations arising from global fallout prior to the Fukushima accident, suggesting that no marked increase of (90)Sr concentrations has occurred in r-Cs positive samples as a result of the Fukushima Daiichi NPP accident.

Virtual Compton scattering and neutral pion electroproduction in the resonance region up to the deep inelastic region at backward angles

NASA Astrophysics Data System (ADS)

Laveissière, G.; Degrande, N.; Jaminion, S.; Jutier, C.; Todor, L.; Salvo, R. Di; Hoorebeke, L. Van; Alexa, L. C.; Anderson, B. D.; Aniol, K. A.; Arundell, K.; Audit, G.; Auerbach, L.; Baker, F. T.; Baylac, M.; Berthot, J.; Bertin, P. Y.; Bertozzi, W.; Bimbot, L.; Boeglin, W. U.; Brash, E. J.; Breton, V.; Breuer, H.; Burtin, E.; Calarco, J. R.; Cardman, L. S.; Cavata, C.; Chang, C.-C.; Chen, J.-P.; Chudakov, E.; Cisbani, E.; Dale, D. S.; de Jager, C. W.; de Leo, R.; Deur, A.; D'Hose, N.; Dodge, G. E.; Domingo, J. J.; Elouadrhiri, L.; Epstein, M. B.; Ewell, L. A.; Finn, J. M.; Fissum, K. G.; Fonvieille, H.; Fournier, G.; Frois, B.; Frullani, S.; Furget, C.; Gao, H.; Gao, J.; Garibaldi, F.; Gasparian, A.; Gilad, S.; Gilman, R.; Glamazdin, A.; Glashausser, C.; Gomez, J.; Gorbenko, V.; Grenier, P.; Guichon, P. A. M.; Hansen, J. O.; Holmes, R.; Holtrop, M.; Howell, C.; Huber, G. M.; Hyde, C. E.; Incerti, S.; Iodice, M.; Jardillier, J.; Jones, M. K.; Kahl, W.; Kamalov, S.; Kato, S.; Katramatou, A. T.; Kelly, J. J.; Kerhoas, S.; Ketikyan, A.; Khayat, M.; Kino, K.; Kox, S.; Kramer, L. H.; Kumar, K. S.; Kumbartzki, G.; Kuss, M.; Leone, A.; Lerose, J. J.; Liang, M.; Lindgren, R. A.; Liyanage, N.; Lolos, G. J.; Lourie, R. W.; Madey, R.; Maeda, K.; Malov, S.; Manley, D. M.; Marchand, C.; Marchand, D.; Margaziotis, D. J.; Markowitz, P.; Marroncle, J.; Martino, J.; McCormick, K.; McIntyre, J.; Mehrabyan, S.; Merchez, F.; Meziani, Z. E.; Michaels, R.; Miller, G. W.; Mougey, J. Y.; Nanda, S. K.; Neyret, D.; Offermann, E. A. J. M.; Papandreou, Z.; Perdrisat, C. F.; Perrino, R.; Petratos, G. G.; Platchkov, S.; Pomatsalyuk, R.; Prout, D. L.; Punjabi, V. A.; Pussieux, T.; Quémenér, G.; Ransome, R. D.; Ravel, O.; Real, J. S.; Renard, F.; Roblin, Y.; Rowntree, D.; Rutledge, G.; Rutt, P. M.; Saha, A.; Saito, T.; Sarty, A. J.; Serdarevic, A.; Smith, T.; Smirnov, G.; Soldi, K.; Sorokin, P.; Souder, P. A.; Suleiman, R.; Templon, J. A.; Terasawa, T.; Tiator, L.; Tieulent, R.; Tomasi-Gustaffson, E.; Tsubota, H.; Ueno, H.; Ulmer, P. E.; Urciuoli, G. M.; de Vyver, R. Van; der Meer, R. L. J. Van; Vernin, P.; Vlahovic, B.; Voskanyan, H.; Voutier, E.; Watson, J. W.; Weinstein, L. B.; Wijesooriya, K.; Wilson, R.; Wojtsekhowski, B. B.; Zainea, D. G.; Zhang, W.-M.; Zhao, J.; Zhou, Z.-L.

2009-01-01

We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e, e'p)γ exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the W-dependence at fixed Q2=1GeV2 and for the Q2 dependence at fixed W near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions. The observed Q2 dependence is smooth. The measured ratio of H(e, e'p)γ to H(e, e'p)π0 cross sections emphasizes the different sensitivity of these two reactions to the various nucleon resonances. Finally, when compared to real Compton scattering (RCS) at high energy and large angles, our VCS data at the highest W (1.8-1.9 GeV) show a striking Q2 independence, which may suggest a transition to a perturbative scattering mechanism at the quark level.

Continuous high PRF waveforms for challenging environments

NASA Astrophysics Data System (ADS)

Jaroszewski, Steven; Corbeil, Allan; Ryland, Robert; Sobota, David

2017-05-01

Current airborne radar systems segment the available time-on-target during each beam dwell into multiple Coherent Processing Intervals (CPIs) in order to eliminate range eclipsing, solve for unambiguous range, and increase the detection performance against larger Radar Cross Section (RCS) targets. As a consequence, these radars do not realize the full Signal-to-Noise Ratio (SNR) increase and detection performance improvement that is possible. Continuous High Pulse Repetition Frequency (HPRF) waveforms and processing enables the coherent integration of all available radar data over the full time-on-target. This can greatly increase the SNR for air targets at long range and/or with weak radar returns and significantly improve the detection performance against such targets. TSC worked with its partner KeyW to implement a Continuous HPRF waveform in their Sahara radar testbed and obtained measured radar data on both a ground vehicle target and an airborne target of opportunity. This experimental data was processed by TSC to validate the expected benefits of Continuous HPRF waveforms.

Study on the millimeter-wave scale absorber based on the Salisbury screen

NASA Astrophysics Data System (ADS)

Yuan, Liming; Dai, Fei; Xu, Yonggang; Zhang, Yuan

2018-03-01

In order to solve the problem on the millimeter-wave scale absorber, the Salisbury screen absorber is employed and designed based on the RL. By optimizing parameters including the sheet resistance of the surface resistive layer, the permittivity and the thickness of the grounded dielectric layer, the RL of the Salisbury screen absorber could be identical with that of the theoretical scale absorber. An example is given to verify the effectiveness of the method, where the Salisbury screen absorber is designed by the proposed method and compared with the theoretical scale absorber. Meanwhile, plate models and tri-corner reflector (TCR) models are constructed according to the designed result and their scattering properties are simulated by FEKO. Results reveal that the deviation between the designed Salisbury screen absorber and the theoretical scale absorber falls within the tolerance of radar Cross section (RCS) measurement. The work in this paper has important theoretical and practical significance in electromagnetic measurement of large scale ratio.

A prototype fully polarimetric 160-GHz bistatic ISAR compact radar range

NASA Astrophysics Data System (ADS)

Beaudoin, C. J.; Horgan, T.; DeMartinis, G.; Coulombe, M. J.; Goyette, T.; Gatesman, A. J.; Nixon, William E.

2017-05-01

We present a prototype bistatic compact radar range operating at 160 GHz and capable of collecting fullypolarimetric radar cross-section and electromagnetic scattering measurements in a true far-field facility. The bistatic ISAR system incorporates two 90-inch focal length, 27-inch-diameter diamond-turned mirrors fed by 160 GHz transmit and receive horns to establish the compact range. The prototype radar range with its modest sized quiet zone serves as a precursor to a fully developed compact radar range incorporating a larger quiet zone capable of collecting X-band bistatic RCS data and 3D imagery using 1/16th scale objects. The millimeter-wave transmitter provides 20 GHz of swept bandwidth in the single linear (Horizontal/Vertical) polarization while the millimeter-wave receiver, that is sensitive to linear Horizontal and Vertical polarization, possesses a 7 dB noise figure. We present the design of the compact radar range and report on test results collected to validate the system's performance.

Large-scale synthesis and microwave absorption enhancement of actinomorphic tubular ZnO/CoFe2O4 nanocomposites.

PubMed

Cao, Jing; Fu, Wuyou; Yang, Haibin; Yu, Qingjiang; Zhang, Yanyan; Liu, Shikai; Sun, Peng; Zhou, Xiaoming; Leng, Yan; Wang, Shuangming; Liu, Bingbing; Zou, Guangtian

2009-04-09

Actinomorphic tubular ZnO/CoFe(2)O(4) nanocomposites were fabricated in large scale via a simple solution method at low temperature. The phase structures, morphologies, particle size, shell thickness, chemical compositions of the composites have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDS), and transmission electron microscopy (TEM). The as-synthesized nanocomposites were uniformly dispersed into the phenolic resin then the mixture was pasted on metal plate with the area of 200 mm x 200 mm as the microwave absorption test plate. The test of microwave absorption was carried out by the radar-absorbing materials (RAM) reflectivity far field radar cross-section (RCS) method. The range of microwave absorption is from 2 to 18 Hz and the best microwave absorption reach to 28.2 dB at 8.5 Hz. The results indicate that the composites are of excellence with respect to microwave absorption.

INJECTION SYSTEM DESIGN FOR THE BSNS/RCS.

DOE Office of Scientific and Technical Information (OSTI.GOV)

WEI, J.; TANG, J.Y.; CHEN, Y.

2006-06-23

The BSNS injection system is designed to take one uninterrupted long drift in one of the four dispersion-free straight sections to host all the injection devices. Painting bumper magnets are used for both horizontal and vertical phase space painting. Closed-orbit bumper magnets are used for facilitating the installation of the injection septa and decreasing proton traversal in the stripping foil. Even with large beam emittance of about 300 {pi}mm.mrad used, BSNS/RCS still approaches the space charge limit during the injection/trapping phase for the accumulated particles of 1.9*10{sup 13} and at the low injection energy of 80 MeV. Uniform-like beam distributionmore » by well-designed painting scheme is then obtained to decrease the tune shift/spread. ORBIT code is used for the 3D simulations. Upgrading to higher injection energy has also been considered.« less

OmpR and RcsB abolish temporal and spatial changes in expression of flhD in Escherichia coli biofilm.

PubMed

Samanta, Priyankar; Clark, Emily R; Knutson, Katie; Horne, Shelley M; Prüß, Birgit M

2013-08-02

Biofilms are communities of bacteria that are characterized by specific phenotypes, including an increased resistance towards anti-microbials and the host immune system. This calls for the development of novel biofilm prevention and treatment options to combat infectious disease. In Escherichia coli, numerous global regulators have been implicated in the control of biofilm associated cell surface organelles. These include the flagellar regulator FlhD/FlhC, the osmoregulator EnvZ/OmpR, and the colanic acid activator RcsCDB. Using flow cell technology and fluorescence microscopy, we determined the temporal expression from flhD::gfp, ompR::gfp, and rcsB::gfp in E. coli biofilm, as well as the impact of the negative regulation of flhD by OmpR and RcsB. Spatial gene expression was investigated from flhD::gfp. The temporal gene expression profile for flhD yielded an early peak at 12 h, a minimum of expression at 35 h, and a second increase in expression towards 51 h of biofilm development. In contrast, the ompR profile showed a peak at 35 h. A mutation in ompR abolished time dependence of flhD expression after the initial growth period of 12 h. Intriguingly, rcsB expression did not correlate inversely with flhD expression, yet a mutation in rcsB abolished time dependence of flhD expression as well. Spatially, expression of flhD was highest in the outermost layer of the biofilm in the parent strain. In ompR and rcsB mutants, flhD was expressed throughout the biofilm. Mutations in both, ompR and rcsB increased flhD expression throughout all temporal and spatial experiments. This increase was paralleled by reductions in biofilm amounts at four tested time points. Our data lead to the conclusion that FlhD/FlhC and its regulation by OmpR and RcsB may be our first target mechanism for the development of novel biofilm prevention and treatment techniques.

OmpR and RcsB abolish temporal and spatial changes in expression of flhD in Escherichia coli Biofilm

PubMed Central

2013-01-01

Background Biofilms are communities of bacteria that are characterized by specific phenotypes, including an increased resistance towards anti-microbials and the host immune system. This calls for the development of novel biofilm prevention and treatment options to combat infectious disease. In Escherichia coli, numerous global regulators have been implicated in the control of biofilm associated cell surface organelles. These include the flagellar regulator FlhD/FlhC, the osmoregulator EnvZ/OmpR, and the colanic acid activator RcsCDB. Using flow cell technology and fluorescence microscopy, we determined the temporal expression from flhD::gfp, ompR::gfp, and rcsB::gfp in E. coli biofilm, as well as the impact of the negative regulation of flhD by OmpR and RcsB. Spatial gene expression was investigated from flhD::gfp. Results The temporal gene expression profile for flhD yielded an early peak at 12 h, a minimum of expression at 35 h, and a second increase in expression towards 51 h of biofilm development. In contrast, the ompR profile showed a peak at 35 h. A mutation in ompR abolished time dependence of flhD expression after the initial growth period of 12 h. Intriguingly, rcsB expression did not correlate inversely with flhD expression, yet a mutation in rcsB abolished time dependence of flhD expression as well. Spatially, expression of flhD was highest in the outermost layer of the biofilm in the parent strain. In ompR and rcsB mutants, flhD was expressed throughout the biofilm. Mutations in both, ompR and rcsB increased flhD expression throughout all temporal and spatial experiments. This increase was paralleled by reductions in biofilm amounts at four tested time points. Conclusion Our data lead to the conclusion that FlhD/FlhC and its regulation by OmpR and RcsB may be our first target mechanism for the development of novel biofilm prevention and treatment techniques. PMID:23914787

Respirable Crystalline Silica (RCS) emissions from industrial plants - Results from measurement programmes in Germany

NASA Astrophysics Data System (ADS)

Ehrlich, C.; Noll, G.; Wusterhausen, E.; Kalkoff, W.-D.; Remus, R.; Lehmann, C.

2013-04-01

Numerous research articles dealing with Respirable Crystalline Silica (RCS) in occupational health because epidemiological studies reveal an association between RCS-dust and the development of silicosis as well as an increased probability of developing lung cancer. Research activities about RCS in ambient air are known from US-measurements. However there is a lack of knowledge regarding RCS-emissions in several industrial sectors. Industrial sources of crystalline silica include construction, foundries, glass manufacturing, abrasive blasting or any industrial or commercial use of silica sand, and mining and rock crushing operations. This paper describes a RCS-emission measurement method for stack gases and report results from the German RCS-emission measurement programmes which were used to identify installations and types of industries with the highest concentration levels of RCS in stack gases. A two-stage cascade impactor was used for the measurements which separate particles into the following size fractions: >10 μm, 10-4 μm und <4 μm of aerodynamic diameter. The measurements were carried out according to international sampling standards. The size of crystalline silica particles of most concern are those respirable particles that are smaller than four microns (millionths of a metre), also called particulate matter 4 (PM4). The analytical procedure of determining crystalline silica in emission samples (in the fraction below 4 μm) consists of using x-ray diffraction and infrared spectroscopy methods which are the same methods as used in the field of occupational health. A total of 37 emission measurement campaigns were assessed (112 RCS-samples in nine industrial sectors). The investigated plants are located in different German states such as Bavaria, North Rhine Westphalia, Baden-Wuerttemberg, Rhineland-Palatinate and Saxony-Anhalt. The results of the measurements show that most of the investigated plants can achieve compliance with the newly developed German emission limit value (ELV) of 1 mg m-3. The ELV is expressed as the concentration of RCS in stack emissions. According to the German emission minimising principle and the precautionary principle it is assumed that by complying with the RCS-ELV there is no ambient air health risk for people living these plants. In the case of increased total dust concentration in the stack gas (more than 20 mg m-3) combined with increased percentage of crystalline silica in PM4 dust, a violation of the above mentioned ELV is more likely. This applies mostly to installations in the silica sand processing industry. To comply with the ELV of 1 mg m-3, efficient emission control technology should be implemented and should be well maintained.

The hard start phenomena in hypergolic engines. Volume 5: RCS engine deformation and destruct tests

NASA Technical Reports Server (NTRS)

Miron, Y.; Perlee, H. E.

1974-01-01

Tests were conducted to determine the causes of Apollo Reaction Control (RCS) engine failures. Stainless steel engines constructed for use in the destructive tests are described. The tests conducted during the three phase investigation are discussed. It was determined that the explosive reaction that destroys the RCS engines occurs at the time of engine ignition and is apparently due to either the detonation of the heterogeneous constituents of the rocket engine, consisting primarily of unreacted propellant droplets and vapors, and/or the detonation of explosive materials accumulated on the engine walls from previous pulses. Photographs of the effects of explosions on the simulated RCS engines are provided.

The spectral energy distributions of isolated neutron stars in the resonant cyclotron scattering model

NASA Astrophysics Data System (ADS)

Tong, Hao; Xu, Renxin

2013-03-01

The X-ray dim isolated neutron stars (XDINSs) are peculiar pulsar-like objects, characterized by their very well Planck-like spectrum. In studying their spectral energy distributions, the optical/UV excess is a long standing problem. Recently, Kaplan et al. (2011) have measured the optical/UV excess for all seven sources, which is understandable in the resonant cyclotron scattering (RCS) model previously addressed. The RCS model calculations show that the RCS process can account for the observed optical/UV excess for most sources. The flat spectrum of RX J2143.0+0654 may due to contribution from bremsstrahlung emission of the electron system in addition to the RCS process.

Utilization of protein in red clover and alfalfa silages by lactating dairy cows and growing lambs.

PubMed

Broderick, Glen A

2018-02-01

Feeding trials were conducted with lactating cows and growing lambs to quantify effects of replacing dietary alfalfa silage (AS) with red clover silage (RCS) on nutrient utilization. The lactation trial had a 2 × 4 arrangement of treatments: AS or RCS fed with no supplement, rumen-protected Met (RPM), rumen-protected Lys (RPL), or RPM plus RPL. Grass silage was fed at 13% of dry matter (DM) with AS to equalize dietary neutral detergent fiber (NDF) and crude protein contents. All diets contained (DM basis) 5% corn silage and 16% crude protein. Thirty-two multiparous (4 ruminally cannulated) plus 16 primiparous Holstein cows were blocked by parity and days in milk and fed diets as total mixed rations in an incomplete 8 × 8 Latin square trial with four 28-d periods. Production data (over the last 14 d of each period) and digestibility and excretion data (at the end of each period) were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC). Although DM intake was 1.2 kg/d greater on AS than RCS, milk yield and body weight gain were not different. However, yields of fat and energy-corrected milk as well as milk content of fat, true protein, and solids-not-fat were greater on AS. Relative to AS, feeding RCS increased milk and energy-corrected milk yield per unit of DM intake, milk lactose content, and apparent N efficiency and reduced milk urea. Relative to AS, apparent digestibility of DM, organic matter, NDF, and acid detergent fiber were greater on RCS, whereas apparent and estimated true N digestibility were lower. Urinary N excretion and ruminal concentrations of ammonia, total AA, and branched-chain volatile fatty acids were reduced on RCS, indicating reduced ruminal protein degradation. Supplementation of RPM increased intake, milk true protein, and solids-not-fat content and tended to increase milk fat content. There were no silage × RPM interactions, suggesting that RPM was equally limiting on both AS and RCS. Supplementation of RPL did not influence any production trait; however, a significant silage × RPL interaction was detected for intake: RPL reduced intake of AS diets but increased intake of RCS diets. Duplicated metabolism trials were conducted with lambs confined to metabolism crates and fed only silage. After adaptation, collections of silage refusals and excreta were made during ad libitum feeding followed by feeding DM restricted to 2% of body weight. Intake of DM was not different when silages were fed ad libitum. Apparent digestibility of DM, organic matter, NDF, and hemicellulose was greater in lambs fed RCS on both ad libitum and restricted intake; however, acid detergent fiber digestibility was only greater at restricted intake. Apparent and estimated true N digestibility was substantially lower, and N retention was reduced, on RCS. Results confirmed greater DM and fiber digestibility in ruminants and N efficiency in cows fed RCS. Specific loss of Lys bioavailability on RCS was not observed. Based on milk composition, Met was the first-limiting AA on both silages; however, Met was not limiting based on production and nutrient efficiency. Depressed true N digestibility suggested impaired intestinal digestibility of rumen-undegraded protein from RCS. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Analysis of Effectiveness of Phoenix Entry Reaction Control System

NASA Technical Reports Server (NTRS)

Dyakonov, Artem A.; Glass, Christopher E.; Desai, Prasun, N.; VanNorman, John W.

2008-01-01

Interaction between the external flowfield and the reaction control system (RCS) thruster plumes of the Phoenix capsule during entry has been investigated. The analysis covered rarefied, transitional, hypersonic and supersonic flight regimes. Performance of pitch, yaw and roll control authority channels was evaluated, with specific emphasis on the yaw channel due to its low nominal yaw control authority. Because Phoenix had already been constructed and its RCS could not be modified before flight, an assessment of RCS efficacy along the trajectory was needed to determine possible issues and to make necessary software changes. Effectiveness of the system at various regimes was evaluated using a hybrid DSMC-CFD technique, based on DSMC Analysis Code (DAC) code and General Aerodynamic Simulation Program (GASP), the LAURA (Langley Aerothermal Upwind Relaxation Algorithm) code, and the FUN3D (Fully Unstructured 3D) code. Results of the analysis at hypersonic and supersonic conditions suggest a significant aero-RCS interference which reduced the efficacy of the thrusters and could likely produce control reversal. Very little aero-RCS interference was predicted in rarefied and transitional regimes. A recommendation was made to the project to widen controller system deadbands to minimize (if not eliminate) the use of RCS thrusters through hypersonic and supersonic flight regimes, where their performance would be uncertain.

Resolving the problem of compliance with the ever increasing and changing regulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leigh, H.

1991-06-01

The most common problem identified at several US Department of Energy (DOE) sites is regulatory compliance. Simply, the project viability depends on identifying regulatory requirements at the beginning of a specific project to avoid possible delays and cost overruns. The Radioisotope Power Systems Facility (RFSP) is using the Regulatory Compliance System (RCS) to deal with the problem that well over 1000 regulatory documents had to be reviewed for possible compliance requirements applicable to the facility. This overwhelming number of possible documents is not atypical of all DOE facilities thus far reviewed using the RCS system. The RCS was developed tomore » provide a control and tracking of all the regulatory and institutional requirements on a given project. WASTREN, Inc., developed the RCS through various DOE contracts and continues to enhance and update the system for existing and new contracts. The RCS provides the information to allow the technical expert to assimilate and manage accurate resource information, compile the checklists, and document that the project or facility fulfills all of the appropriate regulatory requirements. The RCS provides on-line information, including status throughput the project life, thereby allowing more intelligent and proactive decision making. Also, consistency and traceability are provided for regulatory compliance documentation. 1 ref., 1 fig.« less

Subretinally transplanted embryonic stem cells rescue photoreceptor cells from degeneration in the RCS rats.

PubMed

Schraermeyer, U; Thumann, G; Luther, T; Kociok, N; Armhold, S; Kruttwig, K; Andressen, C; Addicks, K; Bartz-Schmidt, K U

2001-01-01

The Royal College of Surgeons (RCS) rat is an animal model for retinal degeneration such as the age-related macular degeneration. The RCS rat undergoes a progressive retinal degeneration during the early postnatal period. A potential treatment to prevent this retinal degeneration is the transplantation into the subretinal space of cells that would replace functions of the degenerating retinal pigment epithelium (RPE) cells or may form neurotrophic factors. In this study we have investigated the potential of subretinally transplanted embryonic stem cells to prevent the genetically determined photoreceptor cell degeneration in the RCS rat. Embryonic stem cells from the inner cell mass of the mouse blastocyst were allowed to differentiate to neural precursor cells in vitro and were then transplanted into the subretinal space of 20-day-old RCS rats. Transplanted and sham-operated rats were sacrificed 2 months following cell transplantation. The eyes were enucleated and photoreceptor degeneration was quantified by analyzing and determining the thickness of the outer nuclear layer by light and electron microscopy. In the eyes transplanted with embryonic cells up to 8 rows of photoreceptor cell nuclei were observed, whereas in nontreated control eyes the outer nuclear layer had degenerated completely. Transplantation of embryonic stem cells appears to delay photoreceptor cell degeneration in RCS rats.

[Effects of Nomega-nitro-L-arginine on photoreceptor apoptosis in inherited retinal degeneration of RCS rats].

PubMed

Li, Ai-jun; Fang, Jun; Zhu, Xiu-an

2004-08-18

To investigate inducible nitric oxide synthase(iNOS) activity of retina and the effects of N(omega)-nitro-L-arginine(N-Arg) on photoreceptor apoptosis in inherited retinal degeneration of Royal College of Surgeons (RCS) rats. iNOS activity was assayed in the whole retinal homogenates of RCS rats and Wistar rats by monitoring the conversion rate of (3)H-arginine to (3)H-citrulline. Intravitreal injection of the NOS inhibitor, N(omega)-nitro-L-arginine(N-Arg), in one lateral eye on postnatal days 17 (P17), P22, P27 and P32 was performed, while the other lateral eye was treated with PBS by intravitreal injection as controls. Then the retinas of the RCS rats were studied by TdT-mediated biotin-dUTP nick-end labeling (TUNEL) for apoptosis on P38. The enzymatic activity of iNOS was elevated in RCS rat retinas on P25. In RCS rats on P38, the percent area of apoptotic photoreceptor nuclei and the thickness of rod and cone layer in the treated group were significantly reduced compared with the controls, while the thickness of outer nuclear layer (ONL) was increased. The inhibitor of NOS might supply a potential medicine for inherited retinal degeneration.

Rapid Clinical Score for the Diagnosis of Tuberculous Meningitis: A Retrospective Cohort Study

PubMed Central

Jipa, Raluca; Olaru, Ioana D.; Manea, Eliza; Merisor, Simona; Hristea, Adriana

2017-01-01

Objective: The aim of our study was to retrospectively validate a previously described rapid clinical score (RCS) in distinguishing tuberculous meningitis (TBM) from viral meningitis (VM) in people who are at increased risk of tuberculosis, as well as from cryptococcal meningitis (CM) in HIV-infected patients. Methods: We performed a retrospective study of patients admitted with a diagnosis of aseptic meningitis between January 2012 and December 2015, to a referral hospital for infectious diseases. The variables included in RCS were duration of symptoms before admission, neurological stage, cerebrospinal fluid (CSF) to blood glucose ratio, and CSF protein. We included in this retrospective study 31 patients with definite or probable TBM including 14 HIV-infected patients, 62 HIV-noninfected patients with VM, and 18 HIV-infected patients with CM. Results: The sensitivity of RCS to distinguish TBM from VM was 96.7%, with a specificity of 81.1% and the area under the receiver operating characteristic (ROC) curve was 0.949 (0.90–0.99). When all four criteria from the RCS were present, the specificity increased at 100%. In HIV-infected patients, the sensitivity and specificity of RCS in differentiating TBM from CM were 86.6% and 27.7%, respectively, and the area under the ROC curve was 0.669 (0.48–0.85). Conclusion: This easy-to-use RCS was found to be helpful in differentiating TBM from VM, with a better sensitivity than molecular amplification techniques and a relatively good specificity. However, the RCS was not useful to differentiate between TBM and CM in HIV-infected patients. PMID:29184338

Opting for rural practice: the influence of medical student origin, intention and immersion experience.

PubMed

Playford, Denese; Ngo, Hanh; Gupta, Surabhi; Puddey, Ian B

2017-08-21

To compare the influence of rural background, rural intent at medical school entry, and Rural Clinical School (RCS) participation on the likelihood of later participation in rural practice. Analysis of linked data from the Medical School Outcomes Database Commencing Medical Students Questionnaire (CMSQ), routinely collected demographic information, and the Australian Health Practitioner Regulation Agency database on practice location. University of Western Australia medical students who completed the CMSQ during 2006-2010 and were practising medicine in 2016. Medical practice in rural areas (ASGC-RAs 2-5) during postgraduate years 2-5. Full data were available for 508 eligible medical graduates. Rural background (OR, 3.91; 95% CI, 2.12-7.21; P < 0.001) and experience in an RCS (OR, 1.93; 95% CI, 1.05-3.54; P = 0.034) were significant predictors of rural practice in the multivariate analysis of all potential factors. When interactions between intention, origin, and RCS experience were included, RCS participation significantly increased the likelihood of graduates with an initial rural intention practising in a rural location (OR, 3.57; 95% CI, 1.25-10.2; P = 0.017). The effect of RCS participation was not significant if there was no pre-existing intention to practise rurally (OR, 1.38; 95% CI, 0.61-3.16; P = 0.44). For students who entered medical school with the intention to later work in a rural location, RCS experience was the deciding factor for realising this intention. Background, intent and RCS participation should all be considered if medical schools are to increase the proportion of graduates working rurally.

Frameworks for evaluating health research capacity strengthening: a qualitative study

PubMed Central

2013-01-01

Background Health research capacity strengthening (RCS) projects are often complex and hard to evaluate. In order to inform health RCS evaluation efforts, we aimed to describe and compare key characteristics of existing health RCS evaluation frameworks: their process of development, purpose, target users, structure, content and coverage of important evaluation issues. A secondary objective was to explore what use had been made of the ESSENCE framework, which attempts to address one such issue: harmonising the evaluation requirements of different funders. Methods We identified and analysed health RCS evaluation frameworks published by seven funding agencies between 2004 and 2012, using a mixed methods approach involving structured qualitative analyses of documents, a stakeholder survey and consultations with key contacts in health RCS funding agencies. Results The frameworks were intended for use predominantly by the organisations themselves, and most were oriented primarily towards funders’ internal organisational performance requirements. The frameworks made limited reference to theories that specifically concern RCS. Generic devices, such as logical frameworks, were typically used to document activities, outputs and outcomes, but with little emphasis on exploring underlying assumptions or contextual constraints. Usage of the ESSENCE framework appeared limited. Conclusions We believe that there is scope for improving frameworks through the incorporation of more accessible information about how to do evaluation in practice; greater involvement of stakeholders, following evaluation capacity building principles; greater emphasis on explaining underlying rationales of frameworks; and structuring frameworks so that they separate generic and project-specific aspects of health RCS evaluation. The third and fourth of these improvements might assist harmonisation. PMID:24330628

[The evaluation of biological effects of exposure to respirable crystalline silica in building industry].

PubMed

Pira, E; Piolatto, P G

2012-01-01

The building industry entails the exposure to Respirable Crystalline Silica (RCS), though there is a large variability among different sectors. The environmental values reported for the current conditions seem to be relatively low. For example the mean exposure estimated by IOM for all industrial sectors in the EU is 0.07 mg/m3. There are few studies in the building sector which show similar values. This is obviously not representative of past exposure. Moreover, the problems of sampling and analysis techniques are still at issue. The well known effect of RCS exposure is silicosis. The carcinogenicity of RCS is still under debate, especially regarding the question of whether RCS is carcinogenic "per se" or whether the risk of developing lung cancer is mediated by silicosis. Although the IARC includes RCS in the Group I (human carcinogen), the reference should be the CLP regulation, of which carcinogen definition criteria allow to state that today there are not sufficient data to classify RCS as a carcinogen and that it seems more appropriate to include RCS in different STOT.RE categories. This is valid for building industry as well as for the other industrial sectors. In Italy the recommended exposure limit is the ACGIH value of 0.025 mg/m3. At EU level it is still debated which is the best choice, based on cost/benefits evaluation, among the following limit values: 0.2, 0.1 and 0.05 respectively. The authors obviously believe that the most protective value should be adopted.

Correction of the retinal dystrophy phenotype of the RCS rat by viral gene transfer of Mertk.

PubMed

Vollrath, D; Feng, W; Duncan, J L; Yasumura, D; D'Cruz, P M; Chappelow, A; Matthes, M T; Kay, M A; LaVail, M M

2001-10-23

The Royal College of Surgeons (RCS) rat is a widely studied animal model of retinal degeneration in which the inability of the retinal pigment epithelium (RPE) to phagocytize shed photoreceptor outer segments leads to a progressive loss of rod and cone photoreceptors. We recently used positional cloning to demonstrate that the gene Mertk likely corresponds to the retinal dystrophy (rdy) locus of the RCS rat. In the present study, we sought to determine whether gene transfer of Mertk to a RCS rat retina would result in correction of the RPE phagocytosis defect and preservation of photoreceptors. We used subretinal injection of a recombinant replication-deficient adenovirus encoding rat Mertk to deliver the gene to the eyes of young RCS rats. Electrophysiological assessment of animals 30 days after injection revealed an increased sensitivity of treated eyes to low-intensity light. Histologic and ultrastructural assessment demonstrated substantial sparing of photoreceptors, preservation of outer segment structure, and correction of the RPE phagocytosis defect in areas surrounding the injection site. Our results provide definitive evidence that mutation of Mertk underlies the RCS retinal dystrophy phenotype, and that the phenotype can be corrected by treatment of juvenile animals. To our knowledge, this is the first demonstration of complementation of both a functional cellular defect (phagocytosis) and a photoreceptor degeneration by gene transfer to the RPE. These results, together with the recent discovery of MERTK mutations in individuals with retinitis pigmentosa, emphasize the importance of the RCS rat as a model for gene therapy of diseases that arise from RPE dysfunction.

Reducing composite restoration polymerization shrinkage stress through resin modified glass-ionomer based adhesives.

PubMed

Naoum, S J; Mutzelburg, P R; Shumack, T G; Thode, Djg; Martin, F E; Ellakwa, A E

2015-12-01

The aim of this study was to determine whether employing resin modified glass-ionomer based adhesives can reduce polymerization contraction stress generated at the interface of restorative composite adhesive systems. Five resin based adhesives (G Bond, Optibond-All-in-One, Optibond-Solo, Optibond-XTR and Scotchbond-Universal) and two resin modified glass-ionomer based adhesives (Riva Bond-LC, Fuji Bond-LC) were analysed. Each adhesive was applied to bond restorative composite Filtek-Z250 to opposing acrylic rods secured within a universal testing machine. Stress developed at the interface of each adhesive-restorative composite system (n = 5) was calculated at 5-minute intervals over 6 hours. The resin based adhesive-restorative composite systems (RBA-RCS) demonstrated similar interface stress profiles over 6 hours; initial rapid contraction stress development (0-300 seconds) followed by continued contraction stress development ≤0.02MPa/s (300 seconds - 6 hours). The interface stress profile of the resin modified glass-ionomer based adhesive-restorative composite systems (RMGIBA-RCS) differed substantially to the RBA-RCS in several ways. Firstly, during 0-300 seconds the rate of contraction stress development at the interface of the RMGIBA-RCS was significantly (p < 0.05) lower than at the interface of the RBA-RCS. Secondly, at 300 seconds and 6 hours the interface contraction stress magnitude of the RMGIBA-RCS was significantly (p < 0.05) lower than the stress of all assessed RBA-RCS. Thirdly, from 300 seconds to 6 hours both the magnitude and rate of interface stress of the RMGIBA-RCS continued to decline over the 6 hours from the 300 seconds peak. The use of resin modified glass-ionomer based adhesives can significantly reduce the magnitude and rate of polymerization contraction stress developed at the interface of adhesive-restorative composite systems. © 2015 Australian Dental Association.

Determination of respirable-sized crystalline silica in different ambient environments in the United Kingdom with a mobile high flow rate sampler utilising porous foams to achieve the required particle size selection

NASA Astrophysics Data System (ADS)

Stacey, Peter; Thorpe, Andrew; Roberts, Paul; Butler, Owen

2018-06-01

Inhalation of respirable crystalline silica (RCS) can cause diseases including silicosis and cancer. Levels of RCS close to an emission source are measured but little is known about the wider ambient exposure from industry emissions or natural sources. The aim of this work is to report the RCS concentrations obtained from a variety of ambient environments using a new mobile respirable (PM4) sampler. A mobile battery powered high flow rate (52 L min-1) sampler was developed and evaluated for particulate aerosol sampling employing foams to select the respirable particle size fraction. Sampling was conducted in the United Kingdom at site boundaries surrounding seven urban construction and demolition and five sand quarry sites. These are compared with data from twelve urban aerosol samples and from repeat measurements from a base line study at a single rural site. The 50% particle size penetration (d50) through the foam was 4.3 μm. Over 85% of predict bias values were with ±10% of the respirable convention, which is based on a log normal curve. Results for RCS from all construction and quarry activities are generally low with a 95 th percentile of 11 μg m-3. Eighty percent of results were less than the health benchmark value of 3 μg m-3 used in some states in America for ambient concentrations. The power cutting of brick and the largest demolition activities gave the highest construction levels. Measured urban background RCS levels were typically below 0.3 μg m-3 and the median RCS level, at a rural background location, was 0.02 μg m-3. These reported ambient RCS concentrations may provide useful baseline values to assess the wider impact of fugitive, RCS containing, dust emissions into the wider environment.

Non-Toxic Orbiter Maneuvering System (OMS) and Reaction Control System

NASA Technical Reports Server (NTRS)

Hurlbert, Eric A.; Nicholson, Leonard S. (Technical Monitor)

1999-01-01

NASA is pursuing the technology and advanced development of a non-toxic (NT) orbital maneuvering system (OMS) and reaction control system (RCS) for shuttle upgrades, RLV, and reusable first stages. The primary objectives of the shuttle upgrades program are improved safety, improved reliability, reduced operations time and cost, improved performance or capabilities, and commonality with future space exploration needs. Non-Toxic OMS/RCS offers advantages in each of these categories. A non-toxic OMS/RCS eliminates the ground hazards and the flight safety hazards of the toxic and corrosive propellants. The cost savings for ground operations are over $24M per year for 7 flights, and the savings increase with increasing flight rate up to $44M per year. The OMS/RCS serial processing time is reduced from 65 days to 13 days. The payload capability can be increased up to 5100 Ibms. The non-toxic OMS/RCS also provides improved space station reboost capability up to 20 nautical miles over the current toxic system of 14 nautical miles. A NT OMS/RCS represents a clear advancement in the SOA over MMH/NTO. Liquid oxygen and ethanol are clean burning, high-density propellants that provide a high degree of commonality with other spacecraft subsystems including life support, power, and thermal control, and with future human exploration and development of space missions. The simple and reliable pressure-fed design uses sub-cooled liquid oxygen at 250 to 350 psia, which allows a propellant to remain cryogenic for longer periods of time. The key technologies are thermal insulation and conditioning techniques are used to maintain the sub-cooling. Phase I successfully defined the system architecture, designed an integrated OMS/RCS propellant tank, analyzed the feed system, built and tested the 870 lbf RCS thrusters, and tested the 6000 lbf OMS engine. Phase 11 is currently being planned for the development and test of full-scale prototype of the system in 1999 and 2000

Restoration of visual response in aged dystrophic RCS rats using AAV-mediated channelopsin-2 gene transfer.

PubMed

Tomita, Hiroshi; Sugano, Eriko; Yawo, Hiromu; Ishizuka, Toru; Isago, Hitomi; Narikawa, Satoko; Kügler, Sebastian; Tamai, Makoto

2007-08-01

To investigate whether the channelopsin-2 (Chop2) gene would restore visual responses in 10-month-old dystrophic Royal College of Surgeons (aged RCS; rdy/rdy) rats, the authors transferred the Chop2 gene into the retinal cells of aged RCS rats using the adenoassociated virus (AAV) vector. The N-terminal fragment (residues 1-315) of Chop2 was fused to a fluorescent protein, Venus, in frame at the end of the Chop2 coding fragment. The viral vector construct (AAV-Chop2V) for the expression of the Chop2V in the retina was made by subcloning into an adenoassociated virus vector, including the CAG promoter. To evaluate the expression profile of Chop2V in the retina, the rats were killed and the eyes were removed and fixed with 4% paraformaldehyde in 0.1 M phosphate-buffered saline. Retinal wholemount specimens and cryosections were made. Under anesthetized conditions, electrodes for the recording of visually evoked potentials (VEPs) were implanted onto the visual cortex in aged-RCS (rdy/rdy) rats. AAV-Chop2V vectors were then injected into the vitreous cavity of the left eyes. As a control, AAV-Venus vectors were applied to the right eyes. VEPs were evoked by the flash of a blue, white, or red light-emitting diode (LED) and were recorded from the visual cortex of the rats at various time points after the AAV vector injection. Chop2V fluorescence was predominantly observed in retinal ganglion cells (RGCs). Some fluorescence was observed in the inner nuclear layer and the inner plexiform layer neurites. A tendency of recovery was observed in the VEPs of aged RCS (rdy/rdy) rats after the AAV-Chop2V injection but not after the AAV-Venus injection. The visual response of AAV-Chop2V-injected aged RCS (rdy/rdy) rats was less sensitive to the blue LED flash than that of nondystrophic RCS (+/+) rats. The AAV-Chop2V-injected aged RCS (rdy/rdy) rats were insensitive to the red LED flash, which evoked a robust VEP in the RCS (+/+) rats. The visual response of aged RCS (rdy/rdy) rats was partially restored by transduction of the Chop2 gene through AAV into the inner retinal neurons, mainly RGCs. These results suggest that the transduction of Chop2 would provide a new strategy to treat some retinitis pigmentosa (RP) symptoms independent of their etiology.

Effect of replacing grass silage with red clover silage on nutrient digestion, nitrogen metabolism, and milk fat composition in lactating cows fed diets containing a 60:40 forage-to-concentrate ratio.

PubMed

Halmemies-Beauchet-Filleau, A; Vanhatalo, A; Toivonen, V; Heikkilä, T; Lee, M R F; Shingfield, K J

2014-01-01

Diets based on red clover silage (RCS) typically increase the concentration of polyunsaturated fatty acids (PUFA) in ruminant meat and milk and lower the efficiency of N utilization compared with grass silages (GS). Four multiparous Finnish Ayrshire cows (108 d postpartum) fitted with rumen cannulas were used in a 4 × 4 Latin square design with 21-d periods to evaluate the effect of incremental replacement of GS with RCS on milk production, nutrient digestion, whole-body N metabolism, and milk fatty acid composition. Treatments comprised total mixed rations offered ad libitum, containing 600 g of forage/kg of diet dry matter (DM), with RCS replacing GS in ratios of 0:100, 33:67, 67:33, and 100:0 on a DM basis. Intake of DM and milk yield tended to be higher when RCS and GS were offered as a mixture than when fed alone. Forage species had no influence on the concentration or secretion of total milk fat, whereas replacing GS with RCS tended to decrease milk protein concentration and yield. Substitution of GS with RCS decreased linearly whole-tract apparent organic matter, fiber, and N digestion. Forage species had no effect on total nonammonia N at the omasum, whereas the flow of most AA at the omasum was higher for diets based on a mixture of forages. Replacing GS with RCS progressively lowered protein degradation in the rumen, increased linearly ruminal escape of dietary protein, and decreased linearly microbial protein synthesis. Incremental inclusion of RCS in the diet tended to lower whole-body N balance, increased linearly the proportion of dietary N excreted in feces and urine, and decreased linearly the utilization of dietary N for milk protein synthesis. Furthermore, replacing GS with RCS decreased linearly milk fat 4:0 to 8:0, 14:0, and 16:0 concentrations and increased linearly 18:2n-6 and 18:3n-3 concentrations, in the absence of changes in cis-9 18:1, cis-9, trans-11 18:2, or total trans fatty acid concentration. Inclusion of RCS in the diet progressively increased the apparent transfer of 18-carbon PUFA from the diet into milk, but had no effect on the amount of 18:2n-6 or 18:3n-3 at the omasum recovered in milk. In conclusion, forage species modified ruminal N metabolism, the flow of AA at the omasum, and whole-body N partitioning. A lower efficiency of N utilization for milk protein synthesis with RCS relative to GS was associated with decreased availability of AA for absorption, with some evidence of an imbalance in the supply of AA relative to requirements. Higher enrichment of PUFA in milk for diets based on RCS was related to an increased supply for absorption, with no indication that forage species substantially altered PUFA bioavailability. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Secondary Startup Neutron Sources as a Source of Tritium in a Pressurized Water Reactor (PWR) Reactor Coolant System (RCS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaver, Mark W.; Lanning, Donald D.

2010-02-01

The hypothesis of this paper is that the Zircaloy clad fuel source is minimal and that secondary startup neutron sources are the significant contributors of the tritium in the RCS that was previously assigned to release from fuel. Currently there are large uncertainties in the attribution of tritium in a Pressurized Water Reactor (PWR) Reactor Coolant System (RCS). The measured amount of tritium in the coolant cannot be separated out empirically into its individual sources. Therefore, to quantify individual contributors, all sources of tritium in the RCS of a PWR must be understood theoretically and verified by the sum ofmore » the individual components equaling the measured values.« less

The structure of volcanic cristobalite in relation to its toxicity; relevance for the variable crystalline silica hazard

PubMed Central

2012-01-01

Background Respirable crystalline silica (RCS) continues to pose a risk to human health worldwide. Its variable toxicity depends on inherent characteristics and external factors which influence surface chemistry. Significant population exposure to RCS occurs during volcanic eruptions, where ashfall may cover hundreds of square km and exposure may last years. Occupational exposure also occurs through mining of volcanic deposits. The primary source of RCS from volcanoes is through collapse and fragmentation of lava domes within which cristobalite is mass produced. After 30 years of research, it is still not clear if volcanic ash is a chronic respiratory health hazard. Toxicological assays have shown that cristobalite-rich ash is less toxic than expected. We investigate the reasons for this by determining the physicochemical/structural characteristics which may modify the pathogenicity of volcanic RCS. Four theories are considered: 1) the reactivity of particle surfaces is reduced due to co-substitutions of Al and Na for Si in the cristobalite structure; 2) particles consist of aggregates of cristobalite and other phases, restricting the surface area of cristobalite available for reactions in the lung; 3) the cristobalite surface is occluded by an annealed rim; 4) dissolution of other volcanic particles affects the surfaces of RCS in the lung. Methods The composition of volcanic cristobalite crystals was quantified by electron microprobe and differences in composition assessed by Welch’s two sample t-test. Sections of dome-rock and ash particles were imaged by scanning and transmission electron microscopy, and elemental compositions of rims determined by energy dispersive X-ray spectroscopy. Results Volcanic cristobalite contains up to 4 wt. % combined Al2O3 and Na2O. Most cristobalite-bearing ash particles contain adhered materials such as feldspar and glass. No annealed rims were observed. Conclusions The composition of volcanic cristobalite particles gives insight into previously-unconsidered inherent characteristics of silica mineralogy which may affect toxicity. The structural features identified may also influence the hazard of other environmentally and occupationally produced silica dusts. Current exposure regulations do not take into account the characteristics that might render the silica surface less harmful. Further research would facilitate refinement of the existing simple, mass-based silica standard by taking into account composition, allowing higher standards to be set in industries where the silica surface is modified. PMID:23164071

The structure of volcanic cristobalite in relation to its toxicity; relevance for the variable crystalline silica hazard.

PubMed

Horwell, Claire J; Williamson, Benedict J; Donaldson, Ken; Le Blond, Jennifer S; Damby, David E; Bowen, Leon

2012-11-19

Respirable crystalline silica (RCS) continues to pose a risk to human health worldwide. Its variable toxicity depends on inherent characteristics and external factors which influence surface chemistry. Significant population exposure to RCS occurs during volcanic eruptions, where ashfall may cover hundreds of square km and exposure may last years. Occupational exposure also occurs through mining of volcanic deposits. The primary source of RCS from volcanoes is through collapse and fragmentation of lava domes within which cristobalite is mass produced. After 30 years of research, it is still not clear if volcanic ash is a chronic respiratory health hazard. Toxicological assays have shown that cristobalite-rich ash is less toxic than expected. We investigate the reasons for this by determining the physicochemical/structural characteristics which may modify the pathogenicity of volcanic RCS. Four theories are considered: 1) the reactivity of particle surfaces is reduced due to co-substitutions of Al and Na for Si in the cristobalite structure; 2) particles consist of aggregates of cristobalite and other phases, restricting the surface area of cristobalite available for reactions in the lung; 3) the cristobalite surface is occluded by an annealed rim; 4) dissolution of other volcanic particles affects the surfaces of RCS in the lung. The composition of volcanic cristobalite crystals was quantified by electron microprobe and differences in composition assessed by Welch's two sample t-test. Sections of dome-rock and ash particles were imaged by scanning and transmission electron microscopy, and elemental compositions of rims determined by energy dispersive X-ray spectroscopy. Volcanic cristobalite contains up to 4 wt. % combined Al(2)O(3) and Na(2)O. Most cristobalite-bearing ash particles contain adhered materials such as feldspar and glass. No annealed rims were observed. The composition of volcanic cristobalite particles gives insight into previously-unconsidered inherent characteristics of silica mineralogy which may affect toxicity. The structural features identified may also influence the hazard of other environmentally and occupationally produced silica dusts. Current exposure regulations do not take into account the characteristics that might render the silica surface less harmful. Further research would facilitate refinement of the existing simple, mass-based silica standard by taking into account composition, allowing higher standards to be set in industries where the silica surface is modified.

Effect of replacing grass silage with red clover silage on ruminal lipid metabolism in lactating cows fed diets containing a 60:40 forage-to-concentrate ratio.

PubMed

Halmemies-Beauchet-Filleau, A; Vanhatalo, A; Toivonen, V; Heikkilä, T; Lee, M R F; Shingfield, K J

2013-09-01

Diets based on red clover silage (RCS) typically increase the concentration of polyunsaturated fatty acids (PUFA) in ruminant milk and meat compared with grass silages (GS), an effect that has been attributed to higher activity of polyphenol oxidase in red clover, promoting ruminal escape of dietary lipid. Four multiparous Finnish Ayrshire cows in mid lactation fitted with rumen cannulas were used in a 4×4 Latin Square design with 21-d experimental periods to evaluate the effects of incremental replacement of GS with RCS on ruminal lipid metabolism, using the omasal sampling technique in combination with Cr-EDTA, Yb acetate, and indigestible neutral detergent fiber as markers. Treatments comprised total mixed rations offered ad libitum containing 600 g of forage/kg of diet dry matter, with RCS replacing GS in a ratio of 0:100, 33:67, 67:33, and 100:0 on a dry matter basis. Silages contained a high proportion of lipid as nonesterified fatty acids (NEFA), with no difference between forage species (75 and 73% for GS and RCS, respectively). Substitution of GS with RCS had no influence on the intakes of NEFA, polar lipid, triacylglycerol, diacylglycerol, monoacylglycerol, or total fatty acids (FA), but altered the ingestion of specific FA. Replacing GS with RCS decreased linearly 18:3n-3 and increased linearly 18:2n-6 intakes. Changes in the proportion of RCS in the diet had no effect on the amounts or on the relative proportions of different lipid fractions at the omasum. On average, NEFA, polar lipid, triacylglycerol, diacylglycerol, and monoacylglycerol accounted for 80, 12, 4.4, 2.4, and 0.8% of total FA in omasal digesta, respectively. Replacement of GS with RCS increased linearly the amount of esterified and nonesterified 18:3n-3 at the omasum. Flows of cis-9 18:1 and 18:2n-6 were also increased linearly in response to RCS in the diet, whereas 3,7,11,15-tetramethyl-16:0 at the omasum was decreased. Replacing GS with RCS in the diet decreased linearly the lipolysis of dietary esterified lipids in the rumen from 85 to 70%. Effects on lipolysis due to forage species were also associated with linear decreases in apparent ruminal 18:3n-3 biohydrogenation from 93 to 85% and a trend toward lowered biohydrogenation of cis-9 18:1 and 18:2n-6 in the rumen. However, forage species had no effect on the flow of bound phenols formed as a consequence of polyphenol oxidase activity at the omasum. In conclusion, despite minimal differences in the extent of lipolysis in silo, lipid and constituent FA in RCS were less susceptible to ruminal lipolysis and biohydrogenation compared with GS. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Internal kinematics of disk galaxies in the local universe

NASA Astrophysics Data System (ADS)

Catinella, Barbara

2005-11-01

This dissertation makes use of a homogeneous sample of several thousand normal, non-interacting, spiral galaxies, for which I-band photometry and optical and/ or radio spectroscopy are available, to investigate the average kinematic properties of disk systems at low redshifts ( z [Special characters omitted.] 0.1). New long-slit Ha rotation curves (RCs) for 402 galaxies, which were incorporated into the larger sample, are presented in this work. The main goals of this thesis are: (a) The definition of a set of average, or template , RCs in bins covering a wide range of galaxy luminosity. The template relations represent an accurate description of the average circular velocity field of local spiral galaxies, and are intended to be a standard reference for more distant samples and to constrain theoretical models of galactic disks. (b) The characterization of the systematics associated with different velocity width measurement techniques, and the derivation of a robust measure of rotational velocity to be used for applications of the Tully-Fisher (TF) distance method. A direct cross-calibration of the optical and radio widths has been obtained. (c) The assessment of the impact of the limitations on optical line widths extracted from fixed apertures, such as those being collected for ~10 6 galaxies by the on-going Sloan Digital Sky Survey (SDSS). Since the SDSS fiber technique generally does not sample the full extent of a galaxy RC, the observed line widths yield rotational width measurements that depend on the redshifts of the objects, on the physical sizes of their line-emitting regions, and on the intrinsic shapes of their RCs. Numerical simulations of these biases have been carried out for galaxies with realistic circular velocity fields (described by the template RCs) in the redshift range covered by the SDSS spectroscopic sample. Statistical corrections to be applied to the aperture line widths as a function of galaxy redshift and luminosity have been derived, and their impact on the TF relation examined. The use of the SDSS line widths, corrected for aperture effects, has the potential to solve the debated issue of luminosity evolution of galaxies at intermediate redshifts.

High level of reduced glutathione contributes to detoxification of lipid peroxide-derived reactive carbonyl species in transgenic Arabidopsis overexpressing glutathione reductase under aluminum stress.

PubMed

Yin, Lina; Mano, Jun'ichi; Tanaka, Kiyoshi; Wang, Shiwen; Zhang, Meijuan; Deng, Xiping; Zhang, Suiqi

2017-10-01

Lipid peroxide-derived reactive carbonyl species (RCS), generated downstream of reactive oxygen species (ROS), are critical damage-inducing species in plant aluminum (Al) toxicity. In mammals, RCS are scavenged primarily by glutathione (reduced form of glutathione, GSH), but in plant Al stress, contribution of GSH to RCS detoxification has not been evaluated. In this study, Arabidopsis plants overexpressing the gene AtGR1 (accession code At3g24170), encoding glutathione reductase (GR), were generated, and their performance under Al stress was examined. These transgenic plants (GR-OE plants) showed higher GSH levels and GSH/GSSG (oxidized form of GSH) ratio, and an improved Al tolerance as they suffered less inhibition of root growth than wild-type under Al stress. Exogenous application of 4-hydroxy-2-nonenal, an RCS responsible for Al toxicity in roots, markedly inhibited root growth in wild-type plants. GR-OE plants suffered significantly smaller inhibition, indicating that the enhanced GSH level increased the capacity of RCS detoxification. The generation of H 2 O 2 due to Al stress in GR-OE plants was lower by 26% than in wild-type. Levels of various RCS, such as malondialdehyde, butyraldehyde, phenylacetaldehyde, (E)-2-heptenal and n-octanal, were suppressed by more than 50%. These results indicate that high levels of GSH and GSH/GSSG ratio by GR overexpression contributed to the suppression of not only ROS, but also RCS. Thus, the maintenance of GSH level by overexpressing GR reinforces dual detoxification functions in plants and is an efficient approach to enhance Al tolerance. © 2017 Scandinavian Plant Physiology Society.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hodgson, Alfred T.; Fisk, William J.; Shendell, Derek G.

Relocatable classrooms (RCs) are widely employed by California school districts to satisfy rapidly expanding space requirements due to population growth and class size reduction policies. There is public concern regarding indoor environmental quality (IEQ) in schools, particularly in RCs, but very little data to support or dispel these concerns. Several studies are investigating various aspects of IEQ in California schools. This laboratory-based study focused on evaluating the emissions of toxic and/or odorous volatile organic compounds (VOCs), including formaldehyde and acetaldehyde, from materials used to finish the interiors of new RCs. Furthermore, the study implemented a procedure for VOC source reductionmore » by testing and selecting lower-emitting materials as substitutes for standard materials. In total, 17 standard and alternate floor coverings, wall panels and ceiling panels were quantitatively tested for emissions of VOCs using smallscale environmental chambers. Working with the largest northern California manufacturer of conventional RCs and two school districts, specifications were developed for four new RCs to be produced in early summer 2001. Two of these will be predominantly finished with standard materials. Alternate carpet systems, an alternate wall panel covering and an alternate ceiling panel were selected for the two other RCs based on the results of the laboratory study and considerations of cost and anticipated performance and maintenance. Particular emphasis was placed on reducing the concentrations of VOCs on California agency lists of toxic compounds. Indoor concentrations of toxic and odorous VOCs were estimated for the four classrooms by mass balance using the measured VOC emission factors, exposed surface areas of the materials in the RCs, and three ventilation rate scenarios. Results indicate that reductions in the concentrations of formaldehyde, acetaldehyde phenol, di(ethylene glycol) butyl ether, vinyl acetate, 1,2,4-trimethylbenzene and 1-methyl-2-pyrrolidinone should be achieved as the result of the source reduction procedure.« less

Effectiveness and Implementation of Evidence-Based Practices in Residential Care Settings

PubMed Central

James, Sigrid; Alemi, Qais; Zepeda, Veronica

2013-01-01

Purpose Prompted by calls to implement evidence-based practices (EBPs) into residential care settings (RCS), this review addresses three questions: (1) Which EBPs have been tested with children and youth within the context of RCS? (2) What is the evidence for their effectiveness within such settings? (3) What implementation issues arise when transporting EBPs into RCS? Methods Evidence-based psychosocial interventions and respective outcome studies, published from 1990–2012, were identified through a multi-phase search process, involving the review of four major clearinghouse websites and relevant electronic databases. To be included, effectiveness had to have been previously established through a comparison group design regardless of the setting, and interventions tested subsequently with youth in RCS. All outcome studies were evaluated for quality and bias using a structured appraisal tool. Results Ten interventions matching a priori criteria were identified: Adolescent Community Reinforcement Approach, Aggression Replacement Training, Dialectical Behavioral Therapy, Ecologically-Based Family Therapy, Eye Movement and Desensitization Therapy, Functional Family Therapy, Multimodal Substance Abuse Prevention, Residential Student Assistance Program, Solution-Focused Brief Therapy, and Trauma Intervention Program for Adjudicated and At-Risk Youth. Interventions were tested in 13 studies, which were conducted in different types of RCS, using a variety of study methods. Outcomes were generally positive, establishing the relative effectiveness of the interventions with youth in RCS across a range of psychosocial outcomes. However, concerns about methodological bias and confounding factors remain. Most studies addressed implementation issues, reporting on treatment adaptations, training and supervision, treatment fidelity and implementation barriers. Conclusion The review unearthed a small but important body of knowledge that demonstrates that EBPs can be implemented in RCS with encouraging results. PMID:23606781

Effectiveness and Implementation of Evidence-Based Practices in Residential Care Settings.

PubMed

James, Sigrid; Alemi, Qais; Zepeda, Veronica

2013-04-01

Prompted by calls to implement evidence-based practices (EBPs) into residential care settings (RCS), this review addresses three questions: (1) Which EBPs have been tested with children and youth within the context of RCS? (2) What is the evidence for their effectiveness within such settings? (3) What implementation issues arise when transporting EBPs into RCS? Evidence-based psychosocial interventions and respective outcome studies, published from 1990-2012, were identified through a multi-phase search process, involving the review of four major clearinghouse websites and relevant electronic databases. To be included, effectiveness had to have been previously established through a comparison group design regardless of the setting, and interventions tested subsequently with youth in RCS. All outcome studies were evaluated for quality and bias using a structured appraisal tool. Ten interventions matching a priori criteria were identified: Adolescent Community Reinforcement Approach, Aggression Replacement Training, Dialectical Behavioral Therapy, Ecologically-Based Family Therapy, Eye Movement and Desensitization Therapy, Functional Family Therapy, Multimodal Substance Abuse Prevention, Residential Student Assistance Program, Solution-Focused Brief Therapy, and Trauma Intervention Program for Adjudicated and At-Risk Youth. Interventions were tested in 13 studies, which were conducted in different types of RCS, using a variety of study methods. Outcomes were generally positive, establishing the relative effectiveness of the interventions with youth in RCS across a range of psychosocial outcomes. However, concerns about methodological bias and confounding factors remain. Most studies addressed implementation issues, reporting on treatment adaptations, training and supervision, treatment fidelity and implementation barriers. The review unearthed a small but important body of knowledge that demonstrates that EBPs can be implemented in RCS with encouraging results.

Effects of Subretinal Electrical Stimulation in Mer-KO Mice

PubMed Central

Mocko, Julie A.; Kim, Moon; Faulkner, Amanda E.; Cao, Yang; Ciavatta, Vincent T.

2011-01-01

Purpose. Subretinal electrical stimulation (SES) from microphotodiode arrays protects photoreceptors in the RCS rat model of retinitis pigmentosa. The authors examined whether merkd mice, which share a Mertk mutation with RCS rats, showed similar neuroprotective effects from SES. Methods. Merkd mice were implanted with a microphotodiode array at postnatal day (P) 14. Weekly electroretinograms (ERGs) followed by retinal histology at week 4 were compared with those of age-matched controls. RT-PCR for fibroblast growth factor beta (Fgf2), ciliary nerve trophic factor (Cntf), glial-derived neurotrophic factor (Gdnf), insulin growth factor 1 (Igf1), and glial fibrillary acidic protein (Gfap) was performed on retinas at 1 week after surgery. Rates of degeneration using ERG parameters were compared between merkd mice and RCS rats from P28 to P42. Results. SES-treated merkd mice showed no differences in ERG a- and b-wave amplitudes or photoreceptor numbers compared with controls. However, the expression of Fgf2 and Cntf was greater (6.5 ± 1.9- and 2.5 ± 0.5-fold, respectively; P < 0.02) in SES-treated merkd retinas. Rates of degeneration were faster for dark-adapted maximal b-wave, log σ, and oscillatory potentials in merkd mice than in RCS rats. Conclusions. Although SES upregulated Fgf2 in merkd retinas, as reported previously for RCS retinas, this was not accompanied by neuroprotection of photoreceptors. Comparisons of ERG responses from merkd mice and RCS rats across different ages showed inner retinal dysfunction in merkd mice but not in RCS rats. This inner retinal dysfunction and the faster rate of degeneration in merkd mice may produce a retinal environment that is not responsive to neuroprotection from SES. PMID:21467171

Mass spectrometric approaches for the identification and quantification of reactive carbonyl species protein adducts.

PubMed

Colzani, Mara; Aldini, Giancarlo; Carini, Marina

2013-10-30

Our current knowledge of the occurrence of proteins covalently modified by reactive carbonyl species (RCS) generated by lipid peroxidation indicates their involvement as pathogenic factors associated with several chronic degenerative diseases. Proteomics and mass spectrometry (MS) in the last decade have played a fundamental role in this context, allowing the demonstration of the formation of RCS-protein adducts in vitro and in vivo under different experimental conditions. In conjunction with functional and computational studies, MS has been widely applied in vitro to study the stoichiometry of the protein-RCS adduct formation, and, by identifying the site(s) of modification, to elucidate the molecular mechanisms of protein carbonylation and the physiologic impact of such modification on protein function. This review will provide an update of the MS methods commonly used in detecting and characterizing protein modification by RCS generated by lipid peroxidation, among which 4-hydroxy-trans-2-nonenal and acrolein represent the most studied and cytotoxic compounds. Research in this field, employing state-of-the-art MS, is rapidly and continuously evolving, owing also to the development of suitable derivatization and enrichment procedures enabling the improve MS detectability of RCS-protein adducts in complex biological matrices. By considering the emerging role of RCS in several human diseases, unequivocal analytical approaches by MS are needed to provide levels of intermediate diagnostic biomarkers for human diseases. This review focuses also on the different MS-based approaches so far developed for RCS-protein adduct quantification. This article is part of a Special Issue entitled: Posttranslational Protein modifications in biology and Medicine. Copyright © 2013 Elsevier B.V. All rights reserved.

Evaluation of Retinal Function and Morphology of the Pink-Eyed Royal College of Surgeons (RCS) Rat: A Comparative Study of in Vivo and in Vitro Methods.

PubMed

Rösch, Sarah; Aretzweiler, Christoph; Müller, Frank; Walter, Peter

2017-02-01

To characterize the course of retinal degeneration in the pink-eyed RCS rat in vivo and in vitro. Retinal function of RCS rats at the age of 2 to 100 weeks was determined in vivo using full-field electroretinography (ERG). Retinal morphology was evaluated in vivo using spectral domain Optical Coherence Tomography (sd-OCT) and Fluorescence angiography (FA) as well as postmortem using immunohistochemistry (IH). As a control, retinal function and morphology of non-dystrophic Wistar rats were analyzed. RCS rats showed an extinction of the ERG beginning with the age of 4 weeks. In the OCT, the outer part of the retina (OPR) could be clearly distinguished from the inner part of the retina (IPR) until the age of 8 weeks. However, at this age, it was impossible to determine from OCT images whether the OPR was formed by the outer nuclear layer (ONL) or by cellular debris built in the course of retinal degeneration. In contrast, immunohistochemistry always enabled to differentiate between ONL and debris (RCS 4 weeks of age: OPR mainly formed by ONL; RCS 8 weeks of age: OPR consisted mainly of cell debris, only 1-2 cell rows of photoreceptor somata were left). In general, data obtained in vivo were confirmed by data obtained post mortem. Apart from the problem to differentiate between debris and ONL at the age of 8 weeks in the RCS rat, ERG and OCT are useful methods to evaluate retinal function and structure in vivo and to complement immunohistochemical analysis of the degeneration process.

The Yersinia pestis Rcs phosphorelay inhibits biofilm formation by repressing transcription of the diguanylate cyclase gene hmsT.

PubMed

Sun, Yi-Cheng; Guo, Xiao-Peng; Hinnebusch, B Joseph; Darby, Creg

2012-04-01

Yersinia pestis, which causes bubonic plague, forms biofilms in fleas, its insect vectors, as a means to enhance transmission. Biofilm development is positively regulated by hmsT, encoding a diguanylate cyclase that synthesizes the bacterial second messenger cyclic-di-GMP. Biofilm development is negatively regulated by the Rcs phosphorelay signal transduction system. In this study, we show that Rcs-negative regulation is accomplished by repressing transcription of hmsT.

Neurosurgery certification in member societies of the World Federation of Neurosurgical Societies: Asia.

PubMed

Gasco, Jaime; Braun, Jonathan D; McCutcheon, Ian E; Black, Peter M

2011-01-01

To objectively compare the complexity and diversity of the certification process in neurological surgery in member societies of the World Federation of Neurosurgical Societies. This study centers in continental Asia. We provide here an analysis based on the responses provided to a 13-item survey. The data received were analyzed, and three Regional Complexity Scores (RCS) were designed. To compare national board experience, eligibility requirements for access to the certification process, and the obligatory nature of the examinations, an RCS-Organizational score was created (20 points maximum). To analyze the complexity of the examination, an RCS-Components score was designed (20 points maximum). The sum of both is presented in a Global RCS score. Only those countries that responded to the survey and presented nationwide homogeneity in the conduction of neurosurgery examinations could be included within the scoring system. In addition, a descriptive summary of the certification process per responding society is also provided. On the basis of the data provided by our RCS system, the highest global RCS was achieved by South Korea and Malaysia (21/40 points) followed by the joint examination of Singapore and Hong-Kong (FRCS-Ed) (20/40 points), Japan (17/40 points), the Philippines (15/40 points), and Taiwan (13 points). The experience from these leading countries should be of value to all countries within Asia. Copyright © 2011 Elsevier Inc. All rights reserved.

Bioinformatics, interaction network analysis, and neural networks to characterize gene expression of radicular cyst and periapical granuloma.

PubMed

Poswar, Fabiano de Oliveira; Farias, Lucyana Conceição; Fraga, Carlos Alberto de Carvalho; Bambirra, Wilson; Brito-Júnior, Manoel; Sousa-Neto, Manoel Damião; Santos, Sérgio Henrique Souza; de Paula, Alfredo Maurício Batista; D'Angelo, Marcos Flávio Silveira Vasconcelos; Guimarães, André Luiz Sena

2015-06-01

Bioinformatics has emerged as an important tool to analyze the large amount of data generated by research in different diseases. In this study, gene expression for radicular cysts (RCs) and periapical granulomas (PGs) was characterized based on a leader gene approach. A validated bioinformatics algorithm was applied to identify leader genes for RCs and PGs. Genes related to RCs and PGs were first identified in PubMed, GenBank, GeneAtlas, and GeneCards databases. The Web-available STRING software (The European Molecular Biology Laboratory [EMBL], Heidelberg, Baden-Württemberg, Germany) was used in order to build the interaction map among the identified genes by a significance score named weighted number of links. Based on the weighted number of links, genes were clustered using k-means. The genes in the highest cluster were considered leader genes. Multilayer perceptron neural network analysis was used as a complementary supplement for gene classification. For RCs, the suggested leader genes were TP53 and EP300, whereas PGs were associated with IL2RG, CCL2, CCL4, CCL5, CCR1, CCR3, and CCR5 genes. Our data revealed different gene expression for RCs and PGs, suggesting that not only the inflammatory nature but also other biological processes might differentiate RCs and PGs. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Promoting early exposure monitoring for respirable crystalline silica: Taking the laboratory to the mine site

PubMed Central

Cauda, Emanuele; Miller, Arthur; Drake, Pamela

2017-01-01

The exposure to respirable crystalline silica (RCS) in the mining industry is a recognized occupational hazard. The assessment and monitoring of the exposure to RCS is limited by two main factors: (1) variability of the silica percent in the mining dust and (2) lengthy off-site laboratory analysis of collected samples. The monitoring of respirable dust via traditional or real-time techniques is not adequate. A solution for on-site quantification of RCS in dust samples is being investigated by the Office of Mine Safety and Health Research, a division of the National Institute for Occupational Safety and Health. The use of portable Fourier transform infrared analyzers in conjunction with a direct-on-filter analysis approach is proposed. The progress made so far, the necessary steps in progress, and the application of the monitoring solution to a small data set is presented. When developed, the solution will allow operators to estimate RCS immediately after sampling, resulting in timelier monitoring of RCS for self-assessment of compliance at the end of the shift, more effective engineering monitoring, and better evaluation of control technologies. PMID:26558490

The quantal nature of Ca2+ sparks and in situ operation of the ryanodine receptor array in cardiac cells.

PubMed

Wang, Shi Qiang; Stern, Michael D; Ríos, Eduardo; Cheng, Heping

2004-03-16

Intracellular Ca(2+) release in many types of cells is mediated by ryanodine receptor Ca(2+) release channels (RyRCs) that are assembled into two-dimensional paracrystalline arrays in the endoplasmic/sarcoplasmic reticulum. However, the in situ operating mechanism of the RyRC array is unknown. Here, we found that the elementary Ca(2+) release events, Ca(2+) sparks from individual RyRC arrays in rat ventricular myocytes, exhibit quantized Ca(2+) release flux. Analysis of the quantal property of Ca(2+) sparks provided a view of unitary Ca(2+) current and gating kinetics of the RyRC in intact cells and revealed that spark activation involves dynamic recruitment of small, variable cohorts of RyRCs. Intriguingly, interplay of RyRCs in multichannel sparks renders an unusual, thermodynamically irreversible mode of channel gating that is unshared by an RyRC acting solo, nor by RyRCs in vitro. Furthermore, an array-based inhibitory feedback, overriding the regenerative Ca(2+)-induced Ca(2+) release of RyRCs, provides a supramolecular mechanism for the microscopic stability of intracellular Ca(2+) signaling.

Is Media Multitasking Good for Cybersecurity? Exploring the Relationship Between Media Multitasking and Everyday Cognitive Failures on Self-Reported Risky Cybersecurity Behaviors.

PubMed

Hadlington, Lee; Murphy, Karen

2018-03-01

The current study focused on how engaging in media multitasking (MMT) and the experience of everyday cognitive failures impact on the individual's engagement in risky cybersecurity behaviors (RCsB). In total, 144 participants (32 males, 112 females) completed an online survey. The age range for participants was 18 to 43 years (M = 20.63, SD = 4.04). Participants completed three scales which included an inventory of weekly MMT, a measure of everyday cognitive failures, and RCsB. There was a significant difference between heavy media multitaskers (HMM), average media multitaskers (AMM), and light media multitaskers (LMM) in terms of RCsB, with HMM demonstrating more frequent risky behaviors than LMM or AMM. The HMM group also reported more cognitive failures in everyday life than the LMM group. A regression analysis showed that everyday cognitive failures and MMT acted as significant predictors for RCsB. These results expand our current understanding of the relationship between human factors and cybersecurity behaviors, which are useful to inform the design of training and intervention packages to mitigate RCsB.

Study of pharmacological effects of nilvadipine on RCS rat retinal degeneration by microarray analysis.

PubMed

Sato, Motoya; Ohguro, Hiroshi; Ohguro, Ikuyo; Mamiya, Kazuhisa; Takano, Yoshiko; Yamazaki, Hitoshi; Metoki, Tomomi; Miyagawa, Yasuhiro; Ishikawa, Fotoshi; Nakazawa, Mitsuru

2003-07-11

In our recent study, we found that the Ca(2+) antagonist, nilvadipine caused significant preservation of photoreceptor cells in The Royal College of Surgeons (RCS) rats [Invest. Ophthalmol. Vis. Sci. 43 (2002) 919]. Here, to elucidate the mechanisms of nilvadipine-induced effects we analyzed altered gene expression of 1101 genes commonly expressed in rodent by DNA microarray analysis in the retinas of nilvadipine-treated and untreated RCS rats and SD rat. In the total number of genes, the expression of 30 genes was altered upon administration of nilvadipine to RCS rats, including several genes related to the apoptotic pathway and other mechanisms. Remarkably, neurotrophic factors, FGF-2 and Arc, known to suppress the apoptosis in the central nervous system, were up-regulated. These changes were also confirmed by real-time quantitative (Taqman) RT-PCR and Western blot analysis. Therefore, our present data suggested that administration of nilvadipine to RCS rats increases the expression of endogenous FGF-2 and Arc in retina, and potentially has a protective effect against retinal degeneration.

Does the Aged Care Funding Instrument provide increased funding in residential care? Comparisons with the Residential Classification Scale.

PubMed

Chan, Geoffrey Z P; Chin, Collin K L; McKitrick, Douglas J; Warne, Roger W

2014-06-01

To determine whether the Aged Care Funding Instrument (ACFI) provides more funding than the Residential Classification Scale (RCS) for residents in the Hellenic Residential Care Facility. All residents within the care facility were assessed over a six 6-month period using ACFI, RCS and Clifton Assessment Procedures for the Elderly (CAPE) scores. Differences in funding levels were calculated using ACFI and RCS instruments against a standardised CAPE score. CAPE dependency RCS funding per resident per day varied from $32.20 for grade A to $116.20 for grade E4 residents. CAPE ACFI funding varied from $20.20 for grade A to $127.50 for grade E4. There was no significant difference in mean overall funding between the two scales (ACFI $92.50 vs RCS $90.35, P = 0.76). The ACFI does provide a small but not significant increase in funding to residents in residential care. It redirects funding to higher dependency residents. © 2013 The Authors. Australasian Journal on Ageing © 2013 ACOTA.

Independent Orbiter Assessment (IOA): Analysis of the reaction control system, volume 1

NASA Technical Reports Server (NTRS)

Burkemper, V. J.; Haufler, W. A.; Odonnell, R. A.; Paul, D. J.

1987-01-01

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results for the Reaction Control System (RCS). The purpose of the RCS is to provide thrust in and about the X, Y, Z axes for External Tank (ET) separation; orbit insertion maneuvers; orbit translation maneuvers; on-orbit attitude control; rendezvous; proximity operations (payload deploy and capture); deorbit maneuvers; and abort attitude control. The RCS is situated in three independent modules, one forward in the orbiter nose and one in each OMS/RCS pod. Each RCS module consists of the following subsystems: Helium Pressurization Subsystem; Propellant Storage and Distribution Subsystem; Thruster Subsystem; and Electrical Power Distribution and Control Subsystem. Of the failure modes analyzed, 307 could potentially result in a loss of life and/or loss of vehicle.

Changes in intrinsic excitability of ganglion cells in degenerated retinas of RCS rats.

PubMed

Ren, Yi-Ming; Weng, Chuan-Huang; Zhao, Cong-Jian; Yin, Zheng-Qin

2018-01-01

To evaluate the intrinsic excitability of retinal ganglion cells (RGCs) in degenerated retinas. The intrinsic excitability of various morphologically defined RGC types using a combination of patch-clamp recording and the Lucifer yellow tracer in retinal whole-mount preparations harvested from Royal College of Surgeons (RCS) rats, a common retinitis pigmentosa (RP) model, in a relatively late stage of retinal degeneration (P90) were investigated. Several parameters of RGC morphologies and action potentials (APs) were measured and compared to those of non-dystrophic control rats, including dendritic stratification, dendritic field diameter, peak amplitude, half width, resting membrane potential, AP threshold, depolarization to threshold, and firing rates. Compared with non-dystrophic control RGCs, more depolarizations were required to reach the AP threshold in RCS RGCs with low spontaneous spike rates and in RCS OFF cells (especially A2o cells), and RCS RGCs maintained their dendritic morphologies, resting membrane potentials and capabilities to generate APs. RGCs are relatively well preserved morphologically and functionally, and some cells are more susceptible to decreased excitability during retinal degeneration. These findings provide valuable considerations for optimizing RP therapeutic strategies.

False belief and relative clauses in Autism Spectrum Disorders.

PubMed

Durrleman, Stephanie; Hinzen, Wolfram; Franck, Julie

Previous studies have suggested sentential complementation is the crucial ingredient of language that relates to false-belief (FB) reasoning, while the role of relative clauses (RCs) is less clear. Nevertheless, under the hypothesis that clausal embedding has a meta-representational effect, arguably implied in FB, one expects a link between FB and not only complementation but also relativization. Seventeen children with ASD (6 to 16 years, mean age 9;2) were assessed for RCs and FB. Comprehension of RCs significantly predicted FB performance, while none of the controlled factors played a predictive role (comprehension of simple sentences, vocabulary, morpho-syntax and working memory). Findings suggest that clausal embedding, common to both sentential complements and RCs, serves as a bootstrap for FB reasoning. Copyright © 2018 Elsevier Inc. All rights reserved.

Results of test 0A82 in the NASA/LRC 31 inch CFHT on an 0.010-scale model (32-0) of the space shuttle configuration 3 to determine RCS jet flow field interaction and to investigate RT real gas effects

NASA Technical Reports Server (NTRS)

Thornton, D. E.

1975-01-01

Tests were conducted in the NASA Langley Research Center 31-inch Continuous Flow Hypersonic Wind Tunnel to determine RCS jet interaction effects on hypersonic aerodynamic characteristics and to investigate RT (gas constant times temperature) scaling effects on the RCS similitude. The model was an 0.010-scale replica of the Space Shuttle Orbiter Configuration 3. Hypersonic aerodynamic data were obtained from tests at Mach 10.3 and dynamic pressures of 200, 150, 125, and 100 psf. The RCS modes of pitch, yaw, and roll at free flight dynamic pressure simulation of 20 psf were investigated.

Comparison of PLIF and CFD Results for the Orion CEV RCS Jets

NASA Technical Reports Server (NTRS)

Ivey, Christopher B.; Danehy, Paul M.; Bathel, Brett F.; Dyakonov, Artem A.; Inman, Jennifer A.; Jones, Stephen B.

2011-01-01

Nitric-oxide planar laser-induced fluorescence (NO PLIF) was used to visualize and measure centerline streamwise velocity of the Orion Crew Exploration Vehicle (CEV) Reaction Control System (RCS) Jets at NASA Langley Research Center's 31-Inch Mach 10 Air wind tunnel. Fluorescence flow visualizations of pitch, roll, and yaw RCS jets were obtained using different plenum pressures and wind tunnel operating stagnation pressures. For two yaw RCS jet test cases, the PLIF visualizations were compared to computational flow imaging (CFI) images based on Langley Aerothermal Upwind Relaxation Algorithm (LAURA) computational fluid dynamics (CFD) simulations of the flowfield. For the same test cases, the streamwise velocity measurements were compared to CFD. The CFD solution, while showing some unphysical artifacts, generally agree with the experimental measurements.

Fate and transport of radionuclides in soil-water environment. Review.

NASA Astrophysics Data System (ADS)

Konoplev, Aleksei

2017-04-01

The ease in which radionuclides move through the environment and are taken up by plants and animals is governed by their chemical forms and by site-specific environmental characteristics. The objective of this paper is to review basic mechanisms of the behavior of radiocesium and radiostrontium in the environment after the nuclear accident. Our understanding of radionuclide's speciation and migration processes seems to be adequate and explains similarities and differences of radiocesium (r-Cs) behavior in the environment after Fukushima and Chernobyl accidents. Climate and geographical conditions in Fukushima Prefecture of Japan and Chernobyl's near-field zone are obviously different. In particular, precipitation differs substantially, with the annual average for Fukushima being about 3 times higher than at Chernobyl. The landscapes and soils also differ significantly. What is more, the speciation of r-Cs in the releases was distinct (large fraction of radionuclides was deposited as fuel particles in 30-km zone around Chernobyl NPP, while in Fukushima radiocesium is mostly part of condensation particles including glassy hot particles). Radiocesium (r-Cs) in the environment is strongly bound to soil and sediment particles containing micaceous clay minerals (illite, vermiculite, etc.), which is associated with two basic processes - high selective reversible sorption and fixation. The r-Cs distribution coefficient Kd in Fukushima rivers was found to be 1-2 orders of magnitude higher than corresponding values for rivers and surface runoff of Chernobyl area. This is indicative of higher ability of Fukushima soils and sediments to bind r-Cs. Dissolved r-Cs wash-off for Fukushima river watersheds is essentially slower than those for Chernobyl. However, steeper slopes and higher precipitation in Fukushima area cause higher erosion and higher particulate r-Cs wash-off. For a comparable time after the accident the total r-Cs wash-off from contaminated catchments in Fukushima is up to one order of magnitude higher than in Chernobyl. Long-term dynamics of radionuclide concentrations in rivers is approached from the standpoint of basic mechanisms of radionuclide sorption-desorption, fixation, vertical migration in catchment soils. Corresponding semi-empirical models are presented and discussed. For the Chernobyl case, radiostrontium (r-Sr) was shown to be more mobile and moving faster in dissolved state with surface runoff and river water in comparison with r-Cs. Similar pattern was observed for Mayak area in South Ural (Russia), where r-Sr was traced up to 1500 km away from the release point migrating through Techa-Iset'-Tobol-Irtysh-Ob' river system. On the other hand, r-Cs bound to clay particles settles down in Techa river reservoirs and is transported with river water only insignificantly. For the first 3 years after the accident vertical migration of r-Cs in soils of Fukushima catchments was found to be faster than in Chernobyl due to higher air temperature, higher precipitation and higher biological activity in top soil. However, with time this process slows down because of higher r-Cs retardation in Fukushima soils. In Fukushima case, extreme floods during typhoons lead to substantial reduction in dose rate on floodplain areas due to sedimentation of relatively clean material and burial of contaminated top soil layer. In general, due to higher precipitation, higher temperatures and higher biological activities in soils, self-purification of the environment and natural attenuation in Fukushima is essentially faster than in Chernobyl area.

Rural origin plus a rural clinical school placement is a significant predictor of medical students' intentions to practice rurally: a multi-university study.

PubMed

Walker, Judith H; Dewitt, Dawn E; Pallant, Julie F; Cunningham, Christine E

2012-01-01

Health workforce shortages are a major problem in rural areas. Australian medical schools have implemented a number of rural education and training interventions aimed at increasing medical graduates' willingness to work in rural areas. These initiatives include recruiting students from rural backgrounds, delivering training in rural areas, and providing all students with some rural exposure during their medical training. However there is little evidence regarding the impact of rural exposure versus rural origin on workforce outcomes. The aim of this study is to identify and assess factors affecting preference for future rural practice among medical students participating in the Australian Rural Clinical Schools (RCS) Program. Questionnaires were distributed to 166 medical students who had completed their RCS term in 2006; 125 (75%) responded. Medical students were asked about their preferred location and specialty for future practice, their beliefs about rural work and life, and the impact of the RCS experience on their future rural training and practice preferences. Almost half the students (47%; n=58) self-reported a 'rural background'. Significantly, students from rural backgrounds were 10 times more likely to prefer to work in rural areas when compared with other students (p<0.001). For those preferring general practice, 80% (n=24) wished to do so rurally. Eighty-five per cent (n=105) of students agreed that their RCS experience increased their interest in rural training and practice with 62% (n=75) of students indicating a preference for rural internship/basic training after their RCS experience. A substantial percentage (86%; n=108) agreed they would consider rural practice after their RCS experience. This baseline study provides significant evidence to support rural medical recruitment and retention through education and training, with important insights into the factors affecting preference for future rural practice. By far the most significant predictor of rural practice intention is recruitment of students with a rural background who also undertake an RCS placement. This research also demonstrates significant demand for post-graduate rural training places, including specialty places, as RCS graduates become junior doctors and vocational trainees.

Resin cements formulated with thio-urethanes can strengthen porcelain and increase bond strength to ceramics.

PubMed

Bacchi, Atais; Spazzin, Aloisio Oro; de Oliveira, Gabriel Rodrigues; Pfeifer, Carmem; Cesar, Paulo Francisco

2018-06-01

The use of thio-urethane oligomers has been shown to significantly improve the mechanical properties of resin cements (RCs). The aim of this study was to use thio-urethane-modified RC to potentially reinforce the porcelain-RC structure and to improve the bond strength to zirconia and lithium disilicate. Six oligomers were synthesized by combining thiols - pentaerythritol tetra-3-mercaptopropionate (PETMP, P) or trimethylol-tris-3-mercaptopropionate (TMP, T) - with di-functional isocyanates - 1,6-Hexanediol-diissocyante (HDDI) (aliphatic, AL) or 1,3-bis(1-isocyanato-1-methylethyl)benzene (BDI) (aromatic, AR) or Dicyclohexylmethane 4,4'-Diisocyanate (HMDI) (cyclic, CC). Thio-urethanes (20 wt%) were added to a BisGMA/UDMA/TEGDMA organic matrix. Filler was introduced at 60 wt%. The microshear bond strength (μSBS), Weibull modulus (m), and failure pattern of RCs bonded to zirconia (ZR) and lithium disilicate (LD) ceramics was evaluated. Biaxial flexural test and fractographic analysis of porcelain discs bonded to RCs were also performed. The biaxial flexural strength (σ bf ) and m were calculated in the tensile surfaces of porcelain and RC structures (Z = 0 and Z = -t 2 , respectively). The μSBS was improved with RCs formulated with oligomers P_AL or T_AL bonded to LD and P_AL, P_AR or T_CC bonded to zirconia in comparison to controls. Mixed failures predominated in all groups. σ bf had superior values at Z = 0 with RCs formulated with oligomers P_AL, P_AR, T_AL, or T_CC in comparison to control; σ bf increased with all RCs composed by thio-urethanes at Z = -t 2 . Fractographic analysis revealed all fracture origins at Z = 0. The use of specific thio-urethane oligomers as components of RCs increased both the biaxial flexural strength of the porcelain-RC structure and the μSBS to LD and ZR. The current investigation suggests that it is possible to reinforce the porcelain-RC pair and obtain higher bond strength to LD and ZR with RCs formulated with selected types of thio-urethane oligomers. Copyright © 2018 Elsevier Ltd. All rights reserved.

Results of the first continuous meteor head echo survey at polar latitudes

NASA Astrophysics Data System (ADS)

Schult, Carsten; Stober, Gunter; Janches, Diego; Chau, Jorge L.

2017-11-01

We present the first quasi continuous meteor head echo measurements obtained during a period of over two years using the Middle Atmosphere ALOMAR Radar System (MAARSY). The measurements yield information on the altitude, trajectory, vector velocity, radar cross section, deceleration and dynamical mass of every single event. The large statistical amount of nearly one million meteor head detections provide an excellent overview of the elevation, altitude, velocity and daily count rate distributions during different times of the year at polar latitudes. Only 40% of the meteors were detected within the full width half maximum of the specific sporadic meteor sources. Our observation of the sporadic meteors are compared to the observations with other radar systems and a meteor input function (MIF). The best way to compare different radar systems is by comparing the radar cross section (RCS), which is the main detection criterion for each system. In this study we aim to compare our observations with a MIF, which provides information only about the meteoroid mass. Thus, we are using a statistical approach for the elevation and velocity dependent visibility and a specific mass selection. The predicted absolute count rates from the MIF are in a good agreement with the observation when it is assumed that the radar system is only sensitive to meteoroids with masses higher than one microgram. The analysis of the dynamic masses seems to be consistent with this assumption since the count rate of events with smaller masses are low and decrease even more by using events with relatively small errors.

Independent Orbiter Assessment (IOA): Analysis of the reaction control system, volume 3

NASA Technical Reports Server (NTRS)

Burkemper, V. J.; Haufler, W. A.; Odonnell, R. A.; Paul, D. J.

1987-01-01

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results for the Reaction Control System (RCS). The RCS is situated in three independent modules, one forward in the orbiter nose and one in each OMS/RCS pod. Each RCS module consists of the following subsystems: Helium Pressurization Subsystem; Propellant Storage and Distribution Subsystem; Thruster Subsystem; and Electrical Power Distribution and Control Subsystem. Volume 3 continues the presentation of IOA analysis worksheets and the potential critical items list.

Quantitative evaluation of retinal degeneration in royal college of surgeons rats by contrast enhanced ultrahigh resolution optical coherence tomography

NASA Astrophysics Data System (ADS)

Syu, Jia-Pu; Su, Min-Jyun; Chen, Po-Wei; Ke, Chang-Chih; Chiou, Shih-Hwa; Kuo, Wen-Chuan

2018-02-01

This study presents a spectral domain optical coherence tomography (SD-OCT) using supercontinuum laser combined with a fundus photography for in vivo high-resolution imaging of retinal degeneration in Royal College of Surgeons (RCS-/- rat). These findings were compared with the Sprague-Dawley (SD) rats and the corresponding histology. Quantitative measurements show that changes in thickness were not significantly different between SD control and young RCS retinas (4 weeks). However, in old RCS rats (55 weeks), the thickness of photoreceptor layer decreased significantly as compared to young RCS rats (both 4 weeks and 5 weeks). After contrast enhancement method, this platform will be useful for the quantitative evaluation of the degree of retinal degeneration, treatment outcome after therapy, and drug screening development in the future.

Role of Reactive Carbonyl Species in non-enzymatic browning of apple juice during storage.

PubMed

Paravisini, Laurianne; Peterson, Devin G

2018-04-15

Non-enzymatic browning during storage of fruit juice causes the development of brown color and off-flavors that ultimately lead to a decrease in consumer acceptability. This study investigates the role of Reactive Carbonyl Species (RCS) from the Maillard reaction on browning formation in apple juice during storage. Over a 10-week period under accelerated conditions (35 °C), a significant increase in brown color development was observed and positively correlated to the RCS concentrations. Supplementation experiments established causality between specific RCS and browning and allowed for the identification of glyoxal and methylglyoxal as key browning intermediates in apple juice. Finally, phloretin, a ubiquitous apple dihydrochalcone, was reported as an efficient browning suppressor by significantly reducing the RCS levels and inhibiting the color formation during storage. Copyright © 2017. Published by Elsevier Ltd.

Modelling of occupational respirable crystalline silica exposure for quantitative exposure assessment in community-based case-control studies.

PubMed

Peters, Susan; Vermeulen, Roel; Portengen, Lützen; Olsson, Ann; Kendzia, Benjamin; Vincent, Raymond; Savary, Barbara; Lavoué, Jérôme; Cavallo, Domenico; Cattaneo, Andrea; Mirabelli, Dario; Plato, Nils; Fevotte, Joelle; Pesch, Beate; Brüning, Thomas; Straif, Kurt; Kromhout, Hans

2011-11-01

We describe an empirical model for exposure to respirable crystalline silica (RCS) to create a quantitative job-exposure matrix (JEM) for community-based studies. Personal measurements of exposure to RCS from Europe and Canada were obtained for exposure modelling. A mixed-effects model was elaborated, with region/country and job titles as random effect terms. The fixed effect terms included year of measurement, measurement strategy (representative or worst-case), sampling duration (minutes) and a priori exposure intensity rating for each job from an independently developed JEM (none, low, high). 23,640 personal RCS exposure measurements, covering a time period from 1976 to 2009, were available for modelling. The model indicated an overall downward time trend in RCS exposure levels of -6% per year. Exposure levels were higher in the UK and Canada, and lower in Northern Europe and Germany. Worst-case sampling was associated with higher reported exposure levels and an increase in sampling duration was associated with lower reported exposure levels. Highest predicted RCS exposure levels in the reference year (1998) were for chimney bricklayers (geometric mean 0.11 mg m(-3)), monument carvers and other stone cutters and carvers (0.10 mg m(-3)). The resulting model enables us to predict time-, job-, and region/country-specific exposure levels of RCS. These predictions will be used in the SYNERGY study, an ongoing pooled multinational community-based case-control study on lung cancer.

Optical imaging of the retina in response to the electrical stimulation

NASA Astrophysics Data System (ADS)

Fujikado, Takashi; Okawa, Yoshitaka; Miyoshi, Tomomitsu; Hirohara, Yoko; Mihashi, Toshifumi; Tano, Yasuo

2008-02-01

Purposes: To determine if reflectance changes of the retina can be detected following electrical stimulation to the retina using a newly developed optical-imaging fundus camera. Methods: Eyes of cats were examined after pupil dilation. Retina was stimulated either focally by a ball-type electrode (BE) placed on the fenestrated sclera or diffusely using a ring-type electrode (RE) placed on the corneoscleral limbus. Electrical stimulation by biphasic pulse trains was applied for 4 seconds. Fundus images with near-infrared (800-880 nm) light were obtained between 2 seconds before and 20 seconds after the electrical stimulation (ES). A two-dimensional map of the reflectance changes (RCs) was constructed. The effect of Tetrodotoxin (TTX) was also investigated on RCs by ES using RE. Results: RCs were observed around the retinal locus where the stimulating electrodes were positioned (BE) or in the retina of the posterior pole (RE), in which the latency was about 0.5 to 1.0 sec and the peak time about 2 to 5 sec after the onset of ES. The intensity of the RCs increased with the increase of the stimulus current in both cases. RCs were completely suppressed after the injection of TTX. Conclusions: The functional changes of the retina either by focal or diffuse electrical stimulation were successfully detected by optical imaging of the retina. The contribution of retinal ganglion cells on RCs by ES was confirmed by TTX experiment. This method may be applied to the objective evaluation of the artificial retina.

Activation of retinal stem cells in the proliferating marginal region of RCS rats during development of retinitis pigmentosa.

PubMed

Jian, Qian; Xu, Haiwei; Xie, Hanping; Tian, Chunyu; Zhao, Tongtao; Yin, ZhengQin

2009-11-06

Retinal stem cells (RSCs) have been demonstrated at the proliferating marginal regions from the pars plana of ciliary body to the ciliary marginal zone (CMZ) in adult lower vertebrates and mammals. Investigations in the lower vertebrates have provided some evidence that RSCs can proliferate following retinal damage; however, the evidence that this occurs in mammals is not clear. In this study, we explored RSCs proliferation potential of adult mammalian in proliferating marginal regions of Royal College of Surgeons (RCS) rats, an animal model for retinitis pigmentosa (RP). The proliferation was evaluated using BrdU labeling, and Chx-10 as markers to discern progenitor cell of CMZ in Long-Evan's and RCS rats at different postnatal day (PND) after eye opening. We found that few Chx-10 and BrdU labeled cells in the proliferating marginal regions of Long-Evan's rats, which significantly increased in RCS rats at PND30 and PND60. Consistent with this, Chx-10/Vimentin double staining cells in the center retina of RCS rats increased significantly at PND30 after eye opening. In addition, mRNA expression of Shh, Ptch1 and Smo was up-regulated in RCS rats at PND60 compared to age-matched Long-Evan's rats, which revealed Shh/ptc pathway involving in the activation of RSCs. These results suggest that RSCs in the mammalian retinal proliferating marginal regions has the potential to regenerate following degeneration.

An evaluation of on-tool shrouds for controlling respirable crystalline silica in restoration stone work.

PubMed

Healy, Catherine B; Coggins, Marie A; Van Tongeren, Martie; MacCalman, Laura; McGowan, Padraic

2014-11-01

The task of grinding sandstone with a 5-inch angle grinder is a major source of exposure to respirable crystalline silica (RCS), known to cause diseases such as silicosis and lung cancer among workers who work with these materials. A shroud may be a suitable engineering control for this task. The objectives of this study were to evaluate the effectiveness of four commercially available shrouds at reducing respirable dust and RCS levels during the task of grinding sandstone using tools and accessories typical of restoration stone work. The task of grinding sandstone with a 5-inch angle grinder, equipped with different grinding wheels, was carried out over three trials at a restoration stone masonry site. Photometric and RCS data were collected when a 5-inch grinder, equipped with different grinding wheels, was used to grind sandstone with and without a shroud. A total of 24 short duration samples were collected for each no shroud and with shroud combination. Worker feedback on the practicalities of each shroud evaluated was also collected. Respirable dust concentrations and RCS were both significantly lower (P < 0.001) when the grinders were equipped with a shroud compared with grinders without a shroud. Total geometric mean (GM) photometric respirable dust levels measured when grinding with a shroud were 0.5 mg m(-3), a reduction of 92% compared to grinding without a shroud (7.1 mg m(-3)). The overall GM RCS concentrations were reduced by the use of a shroud by 99%. GM photometric exposure levels were highest when using the Hilti 5-inch diamond grinding cup and Diamond turbo cup and lowest when using the Corundum grinding point. Concentrations of respirable dust and RCS can be significantly reduced by using commercially available shrouds while grinding sandstone with a 5-inch angle grinder in restoration stonework. The short-term photometric respirable dust and RCS measurements collected with and without a shroud indicate that dust and RCS concentrations are reduced by between 90 and 99%. Supplemental exposure controls such as respiratory protective equipment would be required to reduce worker 8-h time-weighted average RCS exposure to below the Scientific Committee on Occupational Exposure Limits recommended occupational exposure limit value of 0.05 mg m(-3) and the American Conference of Governmental Industrial Hygienists threshold limit value of 0.025 mg m(-3). © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

The internalization of posterior subcapsular cataracts (PSCs) in Royal College of Surgeons (RCS) rats. II. The inter-relationship of optical quality and structure as a function of age.

PubMed

Kuszak, J R; Al-Ghoul, K J; Novak, L A; Peterson, K L; Herbert, K L; Sivak, J G

1999-05-06

The Royal College of Surgeons (RCS) rat is an animal model for human retinal degenerative disease and posterior subcapsular cataracts (PSCs). The purpose of this study was to correlate the structure and optical quality of RCS lenses with PSCs as a function of their internalization, with normal, non-cataractous, age-matched control lenses. Correlative light (LM), scanning electron microscopic (SEM), three-dimensional computer assisted drawings (3D-CADs) and low power helium-neon laser scan analysis were used to examine the structure and function of lenses. The optical properties (average focal length variability; sharpness of focus) of RCS rat lenses are quantitatively compromised by PSCs. Correlative LM and SEM analysis of RCS lenses at various stages of PSC internalization (1.5, 3, 6, 9, 12 and 15 months of age), revealed that the sutures formed by additional fiber growth were progressively more abnormal. During PSC internalization, two to nine small suture branches were formed and arranged in modified line to multiple y configurations rather than the normal three branch y sutures. These temporal changes were also chronicled in animated 3D-CAD videos derived from lens reconstructions based on LM and SEM micrographs from the selected time points stated above. However, laser scan analysis also revealed that as the PSCs of RCS rat lenses were progressively internalized, there was a steady improvement in total sharpness of focus that reached normal levels by 12 months of age. The correlation of laser scan and structural data from specific regions of lenses revealed the following: 1. The abnormal posterior sutures of RCS rats with internalized PSCs effect a greater reduction in optical quality than normal posterior sutures of age-matched controls; 2. However, the resulting abnormal suture plane area was cumulatively similar to that of age-matched controls; 3. Thus, total optical quality was similar between RCS lenses with internalized PSCs and age-matched controls by 12 months of age. The results of this study show that RCS lenses with internalized PSCs can appear grossly, and indeed optically perform, at levels comparable to aged lenses. These findings are consistent with clinical observations of spontaneous recovery from PSC. The results suggest that human PSCs that occur as a consequence of retinal degenerative disease could also be the result of abnormal posterior suture growth. If this is proven to be the case, such PSCs may have some capacity for repair or recovery thereby obviating their surgical removal.

Generalizability of causal inference in observational studies under retrospective convenience sampling.

PubMed

Hu, Zonghui; Qin, Jing

2018-05-20

Many observational studies adopt what we call retrospective convenience sampling (RCS). With the sample size in each arm prespecified, RCS randomly selects subjects from the treatment-inclined subpopulation into the treatment arm and those from the control-inclined into the control arm. Samples in each arm are representative of the respective subpopulation, but the proportion of the 2 subpopulations is usually not preserved in the sample data. We show in this work that, under RCS, existing causal effect estimators actually estimate the treatment effect over the sample population instead of the underlying study population. We investigate how to correct existing methods for consistent estimation of the treatment effect over the underlying population. Although RCS is adopted in medical studies for ethical and cost-effective purposes, it also has a big advantage for statistical inference: When the tendency to receive treatment is low in a study population, treatment effect estimators under RCS, with proper correction, are more efficient than their parallels under random sampling. These properties are investigated both theoretically and through numerical demonstration. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Utschig, L. M.; Dalosto, S. D.; Thurnauer, M. C.

Metal ion binding to a surface site on photosynthetic reaction centers (RCs) modulates light-induced electron and proton transfer events in the RC. Whereas many studies have elucidated aspects of metal ion modulation events in Rhodobacter sphaeroides RCs, much less is understood about the surface site in Blastochloris viridis (Blc. viridis) RCs. Interestingly, electron paramagnetic resonance studies revealed two spectroscopically distinct Cu{sup 2+} surface site environments in Blc. viridis RCs. Herein, Cu{sup 2+} has been used to spectroscopically probe the structure of these Cu{sup 2+} site(s) in response to freezing conditions, temperature, and charge separation. One Cu{sup 2+} environment in Blc.more » viridis RCs, termed CuA, exhibits temperature-dependent conformational flexibility. Different conformation states of the CuA{sup 2+} site are trapped when the RC is frozen in the dark either by fast-freeze or slow-freeze procedure. The second Cu{sup 2+} environment, termed CuB, is structurally invariant to different freezing conditions and shows resolved hyperfine coupling to three nitrogen atoms. Cu{sup 2+} is most likely binding at the same location on the RC, but in different coordination environments which may reflect two distinct conformational states of the isolated Blc. viridis RC protein.« less

Is Media Multitasking Good for Cybersecurity? Exploring the Relationship Between Media Multitasking and Everyday Cognitive Failures on Self-Reported Risky Cybersecurity Behaviors

PubMed Central

Murphy, Karen

2018-01-01

Abstract The current study focused on how engaging in media multitasking (MMT) and the experience of everyday cognitive failures impact on the individual's engagement in risky cybersecurity behaviors (RCsB). In total, 144 participants (32 males, 112 females) completed an online survey. The age range for participants was 18 to 43 years (M = 20.63, SD = 4.04). Participants completed three scales which included an inventory of weekly MMT, a measure of everyday cognitive failures, and RCsB. There was a significant difference between heavy media multitaskers (HMM), average media multitaskers (AMM), and light media multitaskers (LMM) in terms of RCsB, with HMM demonstrating more frequent risky behaviors than LMM or AMM. The HMM group also reported more cognitive failures in everyday life than the LMM group. A regression analysis showed that everyday cognitive failures and MMT acted as significant predictors for RCsB. These results expand our current understanding of the relationship between human factors and cybersecurity behaviors, which are useful to inform the design of training and intervention packages to mitigate RCsB. PMID:29638157

Changes in intrinsic excitability of ganglion cells in degenerated retinas of RCS rats

PubMed Central

Ren, Yi-Ming; Weng, Chuan-Huang; Zhao, Cong-Jian; Yin, Zheng-Qin

2018-01-01

AIM To evaluate the intrinsic excitability of retinal ganglion cells (RGCs) in degenerated retinas. METHODS The intrinsic excitability of various morphologically defined RGC types using a combination of patch-clamp recording and the Lucifer yellow tracer in retinal whole-mount preparations harvested from Royal College of Surgeons (RCS) rats, a common retinitis pigmentosa (RP) model, in a relatively late stage of retinal degeneration (P90) were investigated. Several parameters of RGC morphologies and action potentials (APs) were measured and compared to those of non-dystrophic control rats, including dendritic stratification, dendritic field diameter, peak amplitude, half width, resting membrane potential, AP threshold, depolarization to threshold, and firing rates. RESULTS Compared with non-dystrophic control RGCs, more depolarizations were required to reach the AP threshold in RCS RGCs with low spontaneous spike rates and in RCS OFF cells (especially A2o cells), and RCS RGCs maintained their dendritic morphologies, resting membrane potentials and capabilities to generate APs. CONCLUSION RGCs are relatively well preserved morphologically and functionally, and some cells are more susceptible to decreased excitability during retinal degeneration. These findings provide valuable considerations for optimizing RP therapeutic strategies. PMID:29862172

Layer-specific blood-flow MRI of retinitis pigmentosa in RCS rats☆

PubMed Central

Li, Guang; Garza, Bryan De La; Shih, Yen-Yu I.; Muir, Eric R.; Duong, Timothy Q.

2013-01-01

The Royal College of Surgeons (RCS) rat is an established animal model of retinitis pigmentosa, a family of inherited retinal diseases which starts with loss of peripheral vision and progresses to eventual blindness. Blood flow (BF), an important physiological parameter, is intricately coupled to metabolic function under normal physiological conditions and is perturbed in many neurological and retinal diseases. This study reports non-invasive high-resolution MRI (44 × 44 × 600 μm) to image quantitative retinal and choroidal BF and layer-specific retinal thicknesses in RCS rat retinas at different stages of retinal degeneration compared with age-matched controls. The unique ability to separate retinal and choroidal BF was made possible by the depth-resolved MRI technique. RBF decreased with progressive retinal degeneration, but ChBF did not change in RCS rats up to post-natal day 90. We concluded that choroidal and retinal circulations have different susceptibility to progressive retinal degeneration in RCS rats. Layer-specific retinal thickness became progressively thinner and was corroborated by histological analysis in the same animals. MRI can detect progressive anatomical and BF changes during retinal degeneration with laminar resolution. PMID:22721720

Layer-specific blood-flow MRI of retinitis pigmentosa in RCS rats.

PubMed

Li, Guang; De La Garza, Bryan; Shih, Yen-Yu I; Muir, Eric R; Duong, Timothy Q

2012-08-01

The Royal College of Surgeons (RCS) rat is an established animal model of retinitis pigmentosa, a family of inherited retinal diseases which starts with loss of peripheral vision and progresses to eventual blindness. Blood flow (BF), an important physiological parameter, is intricately coupled to metabolic function under normal physiological conditions and is perturbed in many neurological and retinal diseases. This study reports non-invasive high-resolution MRI (44 × 44 × 600 μm) to image quantitative retinal and choroidal BF and layer-specific retinal thicknesses in RCS rat retinas at different stages of retinal degeneration compared with age-matched controls. The unique ability to separate retinal and choroidal BF was made possible by the depth-resolved MRI technique. RBF decreased with progressive retinal degeneration, but ChBF did not change in RCS rats up to post-natal day 90. We concluded that choroidal and retinal circulations have different susceptibility to progressive retinal degeneration in RCS rats. Layer-specific retinal thickness became progressively thinner and was corroborated by histological analysis in the same animals. MRI can detect progressive anatomical and BF changes during retinal degeneration with laminar resolution. Copyright © 2012 Elsevier Ltd. All rights reserved.

A Contingency in the Rosetta Reaction Control System: Alternative Cruise Trajectory Strategies to Cope with Degraded Delta-V Resources

NASA Technical Reports Server (NTRS)

Bauske, Rainer; Companys, Vincente

2007-01-01

Since August 2006 a pressure transducer of the Rosetta Reaction Control System (RCS) shows anomalous telemetries indicating a possible leak in a pressurant line. The future operation mode of the RCS may be affected by this problem, resulting in performance degradation. The current propellant budget and its future evolution are evaluated to show the possible states w.r.t. the required mission delta-V. Alternative cruise trajectory strategies are analyzed, providing delta-V savings, to compensate for the expected performance loss of the RCS.

Integrable RCS as a Proposed Replacement for Fermilab Booster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eldred, Jeffrey; Valishev, Alexander

2017-03-07

Integrable optics is an innovation in particle accelerator design that potentially enables a greater betatron tune spread and damps collective instabilities. An integrable rapid-cycling synchrotron (RCS) would be an effective replacement for the Fermilab Booster, as part of a plan to reach multi-MW beam power at 120 GeV for the Fermilab high-energy neutrino program. We provide an example integrable lattice with features of a modern RCS - dispersion-free drifts, low momentum compaction factor, superperiodicity, chromaticity correction, bounded beta functions, and separate-function magnets.

10′(Z),13′(E)-Heptadecadienylhydroquinone Inhibits Swarming and Virulence Factors and Increases Polymyxin B Susceptibility in Proteus mirabilis

PubMed Central

Wang, Won-Bo; Yuan, Yu-Han; Hsueh, Po-Ren; Liaw, Shwu-Jen

2012-01-01

In this study, we demonstrated that 10′(Z), 13′(E)-heptadecadienylhydroquinone (HQ17-2), isolated from the lacquer tree, could decrease swarming motility and hemolysin activity but increase polymyxin B (PB) susceptibilityof Proteus mirabilis which is intrinsically highly-resistant to PB. The increased PB susceptibility induced by HQ17-2 was also observed in clinical isolates and biofilm-grown cells. HQ17-2 could inhibit swarming in the wild-type and rppA mutant but not in the rcsB mutant, indicating that HQ17-2 inhibits swarming through the RcsB-dependent pathway, a two-component signaling pathway negatively regulating swarming and virulence factor expression. The inhibition of hemolysin activity by HQ17-2 is also mediated through the RcsB-dependent pathway, because HQ17-2 could not inhibit hemolysin activity in the rcsB mutant. Moreover, the finding that HQ17-2 inhibits the expression of flhDC gene in the wild-type and rcsB-complemented strain but not in the rcsB mutant supports the notion. By contrast, HQ17-2 could increase PB susceptibility in the wild-type and rcsB mutant but not in the rppA mutant, indicating that HQ17-2 increases PB susceptibility through the RppA-dependent pathway, a signaling pathway positively regulating PB resistance. In addition, HQ17-2 could inhibit the promoter activities of rppA and pmrI, a gene positively regulated by RppA and involved in PB resistance, in the wild-type but not in the rppA mutant. The inhibition of rppA and pmrI expression caused lipopolysaccharide purified from HQ17-2-treated cells to have higher affinity for PB. Altogether, this study uncovers new biological effects of HQ17-2 and provides evidence for the potential of HQ17-2 in clinical applications. PMID:23029100

Biophysical Network Modelling of the dLGN Circuit: Different Effects of Triadic and Axonal Inhibition on Visual Responses of Relay Cells.

PubMed

Heiberg, Thomas; Hagen, Espen; Halnes, Geir; Einevoll, Gaute T

2016-05-01

Despite its prominent placement between the retina and primary visual cortex in the early visual pathway, the role of the dorsal lateral geniculate nucleus (dLGN) in molding and regulating the visual signals entering the brain is still poorly understood. A striking feature of the dLGN circuit is that relay cells (RCs) and interneurons (INs) form so-called triadic synapses, where an IN dendritic terminal can be simultaneously postsynaptic to a retinal ganglion cell (GC) input and presynaptic to an RC dendrite, allowing for so-called triadic inhibition. Taking advantage of a recently developed biophysically detailed multicompartmental model for an IN, we here investigate putative effects of these different inhibitory actions of INs, i.e., triadic inhibition and standard axonal inhibition, on the response properties of RCs. We compute and investigate so-called area-response curves, that is, trial-averaged visual spike responses vs. spot size, for circular flashing spots in a network of RCs and INs. The model parameters are grossly tuned to give results in qualitative accordance with previous in vivo data of responses to such stimuli for cat GCs and RCs. We particularly investigate how the model ingredients affect salient response properties such as the receptive-field center size of RCs and INs, maximal responses and center-surround antagonisms. For example, while triadic inhibition not involving firing of IN action potentials was found to provide only a non-linear gain control of the conversion of input spikes to output spikes by RCs, axonal inhibition was in contrast found to substantially affect the receptive-field center size: the larger the inhibition, the more the RC center size shrinks compared to the GC providing the feedforward excitation. Thus, a possible role of the different inhibitory actions from INs to RCs in the dLGN circuit is to provide separate mechanisms for overall gain control (direct triadic inhibition) and regulation of spatial resolution (axonal inhibition) of visual signals sent to cortex.

AC magnetic field measurement using a small flip coil system for rapid cycling AC magnets at the China Spallation Neutron Source (CSNS)

NASA Astrophysics Data System (ADS)

Zhou, Jianxin; Kang, Wen; Li, Shuai; Liu, Yudong; Liu, Yiqin; Xu, Shouyan; Guo, Xiaoling; Wu, Xi; Deng, Changdong; Li, Li; Wu, Yuwen; Wang, Sheng

2018-02-01

The China Spallation Neutron Source (CSNS) has two major accelerator systems, a linear accelerator and a rapid cycling synchrotron (RCS). The RCS accelerator is used to accumulate and accelerate protons from the energy of 80 MeV to the design energy of 1.6 GeV at the repetition rate of 25 Hz, and extract the high energy beam to the target. The main magnets of the RCS accelerator are excited by AC current with DC bias. The magnetic field quality is very important for the RCS accelerator operation, since it should guarantee and focus a circulating beam. In order to characterize the AC magnets, a small flip coil measurement system has been developed and one of each type of AC magnets has been studied. The measurement system and selected measurement results are presented in this paper.

Study of scattering from turbulence structure generated by propeller with FLUENT

NASA Astrophysics Data System (ADS)

Luo, Gen

2017-07-01

In this article, the turbulence structure generated by a propeller is simulated with the computational fluid dynamics (CFD) software FLUENT. With the method of moments, the backscattering radar cross sections (RCS) of the turbulence structure are calculated. The scattering results can reflect the turbulent intensity of the wave profiles. For the wake turbulence with low rotating speed, the scattering intensity of HH polarization is much smaller than VV polarization at large incident angles. When the turbulence becomes stronger with high rotating speed, the scattering intensity of HH polarization also becomes stronger at large incident angles, which is almost the same with VV polarization. And also, the bistatic scattering of the turbulence structure has the similar situation. These scattering results indicate that the turbulence structure can also give rise to an anomaly compared with traditional sea surface. The study of electromagnetic (EM) scattering from turbulence structure generated by the propeller can help in better understanding of the scattering from different kinds of waves and provide more bases to explain the anomalies of EM scattering from sea surfaces.

Toward Improved Catholyte Materials for Redox Flow Batteries: What Controls Chemical Stability of Persistent Radical Cations?

DOE PAGES

Zhang, Jingjing; Shkrob, Ilya A.; Assary, Rajeev S.; ...

2017-10-06

We report catholyte materials are used to store positive charge in energized fluids circulating through redox flow batteries (RFBs) for electric grid and vehicle applications. Energy-rich radical cations (RCs) are being considered for use as catholyte materials, but to be practically relevant, these RCs (that are typically unstable, reactive species) need to have long lifetimes in liquid electrolytes under the ambient conditions. Only few families of such energetic RCs possess stabilities that are suitable for their use in RFBs; currently, the derivatives of 1,4- dialkoxybenzene look the most promising. In this study, we examine factors that define the chemical andmore » electrochemical stabilities for RCs in this family. To this end, we engineered rigid bis-annulated molecules that by design avoid the two main degradation pathways for such RCs, viz. their deprotonation and radical addition. The decay of the resulting RCs are due to the single remaining reaction: O-dealkylation. We establish the mechanism for this reaction and examine factors controlling its rate. In particular, we demonstrate that this reaction is initiated by the nucleophile attack of the counter anion on the RC partner. The reaction proceeds through the formation of the aroxyl radicals whose secondary reactions yield the corresponding quinones. The O-dealkylation accelerates considerably when the corresponding quinone has poor solubility in the electrolyte, and the rate depends strongly on the solvent polarity. Finally, our mechanistic insights suggest new ways of improving the RC catholytes through molecular engineering and electrolyte optimization.« less

Toward Improved Catholyte Materials for Redox Flow Batteries: What Controls Chemical Stability of Persistent Radical Cations?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jingjing; Shkrob, Ilya A.; Assary, Rajeev S.

We report catholyte materials are used to store positive charge in energized fluids circulating through redox flow batteries (RFBs) for electric grid and vehicle applications. Energy-rich radical cations (RCs) are being considered for use as catholyte materials, but to be practically relevant, these RCs (that are typically unstable, reactive species) need to have long lifetimes in liquid electrolytes under the ambient conditions. Only few families of such energetic RCs possess stabilities that are suitable for their use in RFBs; currently, the derivatives of 1,4- dialkoxybenzene look the most promising. In this study, we examine factors that define the chemical andmore » electrochemical stabilities for RCs in this family. To this end, we engineered rigid bis-annulated molecules that by design avoid the two main degradation pathways for such RCs, viz. their deprotonation and radical addition. The decay of the resulting RCs are due to the single remaining reaction: O-dealkylation. We establish the mechanism for this reaction and examine factors controlling its rate. In particular, we demonstrate that this reaction is initiated by the nucleophile attack of the counter anion on the RC partner. The reaction proceeds through the formation of the aroxyl radicals whose secondary reactions yield the corresponding quinones. The O-dealkylation accelerates considerably when the corresponding quinone has poor solubility in the electrolyte, and the rate depends strongly on the solvent polarity. Finally, our mechanistic insights suggest new ways of improving the RC catholytes through molecular engineering and electrolyte optimization.« less

Bcl-2 expression during the development and degeneration of RCS rat retinae.

PubMed

Sharma, R K

2001-12-14

In various hereditary retinal degenerations, including that in Royal College of Surgeons (RCS) rats, the photoreceptors ultimately die by apoptosis. Bcl-2 is one of the genes, which regulates apoptosis and is thought to promote survival of cells. This study has investigated the developmental expression of Bcl-2 in RCS rat, which is a well-studied animal model for hereditary retinal degeneration. An antibody against Bcl-2 was used for its immunohistochemical localization in dystrophic RCS rat retinae from postnatal (PN) days 4, 7, 13, 35, 45, 70, 202 and 14 months. Results were compared with Bcl-2 localization in congenic non-dystrophic rats from PN 4, 7, 13, 44, 202 and 14 months. Bcl-2 immunoreactivity in non-dystrophic retinae was already present in PN 4 retinae in the nerve fiber layer (presumably in the endfeet of immature Müller cells) and in the proximal parts of certain radially aligned neuroepithelial cells/immature Müller cell radial processes. With increasing age the immunoreactivity in relatively more mature Müller cell radial processes spread distally towards the outer retina and between PN 13 and 44 it reached the adult distribution. No cell bodies in the ganglion cell layer were found to be immunoreactive. Expression of Bcl-2 immunoreactivity in dystrophic RCS rat retinae closely resembled that of non-dystrophic retinae. No immunoreactivity was seen in photoreceptors or retinal pigment epithelium in dystrophic or non-dystrophic retinae. In conclusion, Bcl-2 expression is not altered, either in terms of its chronology or the cell type expressing it, during retinal degeneration in RCS rats.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Utschig, L. M.; Poluektov, O.; Schlesselman, S. L.

The interaction of metal ions with isolated photosynthetic reaction centers (RCs) from the purple bacteria Rhodobacter sphaeroides, Rhodobacter capsulatus, and Rhodopseudomonas viridis has been investigated with transient optical and magnetic resonance techniques. In RCs from all species, the electrochromic response of the bacteriopheophytin cofactors associated with Q{sub A}{sup -}Q{sub B} {yields} Q{sub A}Q{sub B}{sup -} electron transfer is slowed in the presence of Cu{sup 2+}. This slowing is similar to the metal ion effect observed for RCs from Rb. sphaeroides where Zn{sup 2+} was bound to a specific site on the surface of the RC [Utschig et al. (1998) Biochemistrymore » 37, 8278]. The coordination environments of the Cu{sup 2+} sites were probed with electron paramagnetic resonance (EPR) spectroscopy, providing the first direct spectroscopic evidence for the existence of a second metal site in RCs from Rb. capsulatus and Rps. viridis. In the dark, RCs with Cu{sup 2+} bound to the surface exhibit axially symmetric EPR spectra. Electron spin echo envelope modulation (ESEEM) spectral results indicate multiple weakly hyperfine coupled {sup 14}N nuclei in close proximity to Cu{sup 2+}. These ESEEM spectra resemble those observed for Cu{sup 2+} RCs from Rb. sphaeroides [Utschig et al. (2000) Biochemistry 39, 2961] and indicate that two or more histidines ligate the Cu{sup 2+} at the surface site in each RC. Thus, RCs from Rb. sphaeroides, Rb. capsulatus, and Rps. viridis each have a structurally analogous Cu{sup 2+} binding site that is involved in modulating the Q{sub A}{sup -}Q{sub B} {yields} Q{sub A}Q{sub B}{sup -} electron-transfer process. Inspection of the Rps. viridis crystal structure reveals four potential histidine ligands from three different subunits (M16, H178, H72, and L211) located beneath the Q{sub B} binding pocket. The location of these histidines is surprisingly similar to the grouping of four histidine residues (H68, H126, H128, and L211) observed in the Rb. sphaeroides RC crystal structure. Further elucidation of these Cu{sup 2+} sites will provide a means to investigate localized proton entry into the RCs of Rb. capsulatus and Rps. viridis as well as locate a site of protein motions coupled with electron transfer.« less

Lens epithelium-derived growth factor promotes photoreceptor survival in light-damaged and RCS rats.

PubMed

Machida, S; Chaudhry, P; Shinohara, T; Singh, D P; Reddy, V N; Chylack, L T; Sieving, P A; Bush, R A

2001-04-01

To investigate possible protective effects of lens epithelium-derived growth factor (LEDGF) against photoreceptor death in light-damaged, Royal College of Surgeons (RCS) and P23H rhodopsin transgenic rats. Twelve-week-old Sprague-Dawley (SD), 6-week-old RCS, and 10-day-old P23H (line 1, heterozygote) rats received an intravitreal injection of LEDGF fused with glutathione-S-transferase (GST-LEDGF). Fellow eyes received vehicle and served as control specimens. Two days after the injections, the SD rats were exposed to light of 2000 lux for 48 hours. Corneal Ganzfeld ERGs were recorded 10 days after light damage, at 10 weeks of age in RCS rats, and at 4 weeks of age in P23H rats. The eyes were then processed for histologic analysis. Heat shock protein (hsp) content in the sensory retina was analyzed quantitatively by protein immunoblot. In light-damaged rats, the ERG indicated retinal protection in GST-LEDGF-injected eyes, with b-wave and STR thresholds being 1.14 +/- 0.50 (mean +/- SD) and 0.60 +/- 0.26 log candela (cd)/m2 lower, respectively, than in vehicle-injected eyes (P < 0.01). The GST-LEDGF-treated eyes had maximum b-wave amplitudes that were significantly larger (P < 0.0005), had more than twice as many remaining photoreceptors, and had better organized outer segments than the control eyes. In RCS rats, the treated eyes had 2.76 +/- 0.73 and 0.83 +/- 0.09 log cd/m(2) lower thresholds for the b-wave and STR, respectively (P < 0.005), and had significantly larger maximum b-wave amplitude (P < 0.0005). GST-LEDGF-treated eyes of RCS rats also had more photoreceptors remaining (P < 0.005) and a thinner debris layer than control eyes. In P23H rats, GST-LEDGF treatment did not protect either retinal function or structure. The retinas from GST-LEDGF-treated eyes of SD and RCS rats had higher levels of hsp25 and alphaB-crystallin than vehicle-injected eyes. GST-LEDGF protects photoreceptor structure and function in both light-damaged and RCS rats. The increased expression of hsp25 and alphaB-crystallin may play a role in this protection. The absence of rescue in P23H raises the possibility that some forms of inherited retinal degeneration may not be amenable to treatment by intraocular injection of LEDGF.

Pressure-Fed LOX/LCH4 Reaction Control System for Spacecraft: Transient Modeling and Thermal Vacuum Hotfire Test Results

NASA Technical Reports Server (NTRS)

Atwell, Matthew J.; Hurlbert, Eric A.; Melcher, J. C.; Morehead, Robert L.

2017-01-01

An integrated cryogenic liquid oxygen, liquid methane (LOX/LCH4) reaction control system (RCS) was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. The RCS is a subsystem of the Integrated Cryogenic Propulsion Test Article (ICPTA), a pressure-fed LOX/LCH4 propulsion system composed of a single 2,800 lbf main engine, two 28 lbf RCS engines, and two 7 lbf RCS engines. Propellants are stored in four 48 inch diameter 5083 aluminum tanks that feed both the main engine and RCS engines in parallel. Helium stored cryogenically in a composite overwrapped pressure vessel (COPV) flows through a heat exchanger on the main engine before being used to pressurize the propellant tanks to a design operating pressure of 325 psi. The ICPTA is capable of simultaneous main engine and RCS operation. The RCS engines utilize a coil-on-plug (COP) ignition system designed for operation in a vacuum environment, eliminating corona discharge issues associated with a high voltage lead. There are two RCS pods on the ICPTA, with two engines on each pod. One of these two engines is a heritage flight engine from Project Morpheus. Its sea level nozzle was removed and replaced by an 85:1 nozzle machined using Inconel 718, resulting in a maximum thrust of 28 lbf under altitude conditions. The other engine is a scaled down version of the 28 lbf engine, designed to match the core and overall mixture ratios as well as other injector characteristics. This engine can produce a maximum thrust of 7 lbf with an 85:1 nozzle that was additively manufactured using Inconel 718. Both engines are film-cooled and capable of limited duration gas-gas and gas-liquid operation, as well as steady-state liquid-liquid operation. Each pod contains one of each version, such that two engines of the same thrust level can be fired as a couple on opposite pods. The RCS feed system is composed of symmetrical 3/8 inch lines that tap off of the main propellant manifold to send LOX and LCH4 outboard to the RCS pods. A Thermodynamic Vent System (TVS) is used to condition propellants at each pod by venting through an orifice and then routing the cold expansion products back through tubing that is welded along a large portion of the main RCS feed lines. Prior to final installation on the ICPTA, the RCS engines were tested in a small vacuum chamber at the Johnson Space Center (JSC) Energy Systems Test Area (ESTA) to verify functionality of the new COP ignition system and check out operation of the vacuum nozzles. After engine-level testing, the RCS engines were installed on the vehicle and a series of integrated hot-fire tests were performed at JSC consisting of various pulsing and steady-state firings as well as integrated main engine/RCS operation. The ICPTA was then integrated into the Plum Brook B-2 facility for vacuum and thermal/vacuum testing. Testing in the B-2 facility was composed of multiple thermal and pressure environments. The first set of tests were performed under ambient temperature and altitude pressure conditions. These tests consisted of a range of minimum impulse bit (MIB) pulsing sequences with low duty cycle, analogous to a coast phase in which the RCS is primarily used for station keeping. The primary goal of this sequence is to understand how propellant conditions were effected without an active TVS. In this scenario, consistent gas-gas operation is desirable since it results in a smaller MIB and more efficient propellant consumption. Multiple skin thermocouples are mounted on the feedlines, in addition to a submerged thermocouple on each commodity, in order to gather thermal data on the system. Higher duty cycle pulsing tests were then performed, analogous to an ascent or landing mission phase. The primary goal of this sequence was to examine how well the engines self-conditioned without active TVS when starting from a quiescent state. The TVS was then activated during some tests to demonstrate the capability to quickly condition the engines for higher pulsing demand scenarios. A thermocouple at the TVS outlet allows for the calculation of energy absorbed by the vented propellant. Lastly, tests with longer pulses and multiple engines firing either in sequence or simultaneously were run in order to gather transient system response data on waterhammer. Six total high-speed pressure transducers are installed on the RCS system, one sensor at the end of each propellant manifold line on the pods, and one at the tap-off location for each commodity. This will allow for the accurate characterization of waterhammer in the system under various propellant conditions and firing sequences. Other instrumentation for this test series includes nozzle throat thermocouples, chamber pressure measurement, heat soakback measurement, and tank wall plume impingement temperature measurement. The next set of tests were performed to demonstrate simultaneous main engine and RCS operation. Data from this test will be used to examine if there is any change to nominal operation of the RCS as a result of feed system interaction or other phenomenon. Some of these tests began under high vacuum conditions (target ambient pressure less than 1x10(exp -3) torr) and others began at altitude conditions. The last set of tests were performed with the B-2 cold wall active. Under these tests, many of the same low duty cycle MIB tests were repeated in order to characterize how propellant conditions changed with the lower heat leak. In this scenario the RCS manifold experiences much less heat leak, resulting in a change to how well the engines self-condition. As a result, an increase in maximum waterhammer pressures and a change in natural frequency of the system was expected due to higher density propellants. The lower heat leak should also result in a change to the MIB pulse profile, and data will be examined to understand how MIB repeatability is affected in the different operating environments. Parallel to the test efforts, a set of transient model development efforts were made to predict RCS performance. The primary effort was aimed at producing a SINDA/FLUINT model to predict propellant conditioning up to the engine inlet as a function of different environmental and operating parameters, with the goal of predicting chamber pressure, TVS performance, and propellant consumption over time. Preliminary results for this effort will be presented in comparison with test data. Additional modeling efforts were made using SINDA/FLUINT to predict waterhammer in the system since the software is capable of handling multiphase transient fluid dynamics. These results will be compared with the high-speed pressure transducer test data for validation purposes.

Characterization of a Recoverable Flight Control Computer System

NASA Technical Reports Server (NTRS)

Malekpour, Mahyar; Torres, Wilfredo

1999-01-01

The design and development of a Closed-Loop System to study and evaluate the performance of the Honeywell Recoverable Computer System (RCS) in electromagnetic environments (EME) is presented. The development of a Windows-based software package to handle the time-critical communication of data and commands between the RCS and flight simulation code in real-time while meeting the stringent hard deadlines is also submitted. The performance results of the RCS and characteristics of its upset recovery scheme while exercising flight control laws under ideal conditions as well as in the presence of electromagnetic fields are also discussed.

Comparison of Solid-Water Partitions of Radiocesium in River Waters in Fukushima and Chernobyl Areas.

PubMed

Takahashi, Yoshio; Fan, Qiaohui; Suga, Hiroki; Tanaka, Kazuya; Sakaguchi, Aya; Takeichi, Yasuo; Ono, Kanta; Mase, Kazuhiko; Kato, Kenji; Kanivets, Vladimir V

2017-09-29

Adsorption of radiocesium (RCs) on particulate matters in aquatic environment is important to understand its mobility and bioavailability. We here focused on factors controlling partition of RCs on particulate matters and sediments in Kuchibuto (Fukushima) and Pripyat (Chernobyl) Rivers, though RCs level in water was much smaller than WHO guideline. Moreover, Cs speciation and organic matter-clay mineral interaction were studied: (i) extended X-ray absorption fine structure showed that the contribution of outer-sphere complex of Cs on particulate matters is larger in Chernobyl than in Fukushima and (ii) scanning transmission X-ray microscope revealed larger association of humic substances and clay minerals in Chernobyl partly due to high [Ca 2+ ] in the Pripyat River. Consequently, RCs is more soluble in the Pripyat River due to weaker interaction of RCs with clay minerals caused by the inhibition effect of the adsorbed humic substances. In contrast, particulate matters and sediments in the Kuchibuto River display high adsorption affinity with lesser inhibition effect of adsorbed humic substances. This difference is possibly governed by the geology and soil type of provenances surrounding both catchments (Fukushima: weathered granite; Chernobyl: peat wetland and carbonate platform) which leads to high concentrations of organic matter and Ca 2+ in the Pripyat River.

Edge-diffraction effects in RCS predictions and their importance in systems analysis

NASA Astrophysics Data System (ADS)

Friess, W. F.; Klement, D.; Ruppel, M.; Stein, Volker

1996-06-01

In developing RCS prediction codes a variety of physical effects such as the edge diffraction effect have to be considered with the consequence that the computer effort increases considerably. This fact limits the field of application of such codes, especially if the RCS data serve as input parameters for system simulators which very often need these data for a high number of observation angles and/or frequencies. Vice versa the issues of a system analysis can be used to estimate the relevance of physical effects under system viewpoints and to rank them according to their magnitude. This paper tries to evaluate the importance of RCS predictions containing an edge diffracted field for systems analysis. A double dihedral with a strong depolarizing behavior and a generic airplane design containing many arbitrarily oriented edges are used as test structures. Data of the scattered field are generated by the RCS computer code SIGMA with and without including edge diffraction effects. These data are submitted to the code DORA to determine radar range and radar detectibility and to a SAR simulator code to generate SAR imagery. In both cases special scenarios are assumed. The essential features of the computer codes in their current state are described, the results are presented and discussed under systems viewpoints.

Aerodynamic Interference Due to MSL Reaction Control System

NASA Technical Reports Server (NTRS)

Dyakonov, Artem A.; Schoenenberger, Mark; Scallion, William I.; VanNorman, John W.; Novak, Luke A.; Tang, Chun Y.

2009-01-01

An investigation of effectiveness of the reaction control system (RCS) of Mars Science Laboratory (MSL) entry capsule during atmospheric flight has been conducted. The reason for the investigation is that MSL is designed to fly a lifting actively guided entry with hypersonic bank maneuvers, therefore an understanding of RCS effectiveness is required. In the course of the study several jet configurations were evaluated using Langley Aerothermal Upwind Relaxation Algorithm (LAURA) code, Data Parallel Line Relaxation (DPLR) code, Fully Unstructured 3D (FUN3D) code and an Overset Grid Flowsolver (OVERFLOW) code. Computations indicated that some of the proposed configurations might induce aero-RCS interactions, sufficient to impede and even overwhelm the intended control torques. It was found that the maximum potential for aero-RCS interference exists around peak dynamic pressure along the trajectory. Present analysis largely relies on computational methods. Ground testing, flight data and computational analyses are required to fully understand the problem. At the time of this writing some experimental work spanning range of Mach number 2.5 through 4.5 has been completed and used to establish preliminary levels of confidence for computations. As a result of the present work a final RCS configuration has been designed such as to minimize aero-interference effects and it is a design baseline for MSL entry capsule.

Syngeneic Schwann cell transplantation preserves vision in RCS rat without immunosuppression.

PubMed

McGill, Trevor J; Lund, Raymond D; Douglas, Robert M; Wang, Shaomei; Lu, Bin; Silver, Byron D; Secretan, Matt R; Arthur, Jennifer N; Prusky, Glen T

2007-04-01

To evaluate the efficacy of immunologically compatible Schwann cells transplanted without immunosuppression in the RCS rat retina to preserve vision. Syngeneic (dystrophic RCS) Schwann cells harvested from sciatic nerves were cultured and transplanted into one eye of dystrophic RCS rats at an early stage of retinal degeneration. Allogeneic (Long-Evans) Schwann cells and unoperated eyes served as controls. Vision through transplanted and unoperated eyes was then quantified using two visual behavior tasks, one measuring the spatial frequency and contrast sensitivity thresholds of the optokinetic response (OKR) and the other measuring grating acuity in a perception task. Spatial frequency thresholds measured through syngeneically transplanted eyes maintained near normal spatial frequency sensitivity for approximately 30 weeks, whereas thresholds through control eyes deteriorated to less than 20% of normal over the same period. Contrast sensitivity was preserved through syngeneically transplanted eyes better than through allogeneic and unoperated eyes, at all spatial frequencies. Grating acuity measured through syngeneically transplanted eyes was maintained at approximately 60% of normal, whereas acuity of allogeneically transplanted eyes was significantly lower at approximately 40% of normal. The ability of immunoprivileged Schwann cell transplants to preserve vision in RCS rats indicates that transplantation of syngeneic Schwann cells holds promise as a preventive treatment for retinal degenerative disease.

The influence of rural clinical school experiences on medical students' levels of interest in rural careers.

PubMed

Isaac, Vivian; Watts, Lisa; Forster, Lesley; McLachlan, Craig S

2014-08-28

Australian Rural Clinical School (RCS) programmes have been designed to create experiences that positively influence graduates to choose rural medical careers. Rural career intent is a categorical evaluation measure and has been used to assess the Australian RCS model. Predictors for rural medical career intent have been associated with extrinsic values such as students with a rural background. Intrinsic values such as personal interest have not been assessed with respect to rural career intent. In psychology, a predictor of the motivation or emotion for a specific career or career location is the level of interest. Our primary aims are to model over one year of Australian RCS training, change in self-reported interest for future rural career intent. Secondary aims are to model student factors associated with rural career intent while attending an RCS. The study participants were medical students enrolled in a RCS in the year 2013 at the University of New South Wales (UNSW) and who completed the newly developed self-administered UNSW Undergraduate Destinations Study (UDS) questionnaire. Data were collected at baseline and after one year of RCS training on preferred location for internship, work and intended specialty. Interest for graduate practice location (career intent) was assessed on a five-variable Likert scale at both baseline and at follow-up. A total of 165 students completed the UDS at baseline and 150 students after 1 year of follow-up. Factors associated with intent to practise in a rural location were rural background (χ2 = 28.4, P < 0.001), two or more previous years at an RCS (χ2 = 9.0, P = 0.003), and preference for a rural internship (χ2 = 17.8, P < 0.001). At follow-up, 41% of participants who originally intended to work in a metropolitan location at baseline changed their preference and indicated a preference for a rural location. The level of interest in intended practice location was significantly higher for those intending to work in a rural area than those with intention to work in a metropolitan (urban area) location (t = -3.1, P = 0.002). Initial rural career location intention was associated with increased interest levels after 1 year of follow-up (paired t = -2.3, P = 0.02). When evaluating the success of RCS outcomes with respect to rural workforce destination, both rural practice intentions and level of interest are key factors related to projected career destination. RCS experience can positively influence practice intent (toward rural practice) and interest levels (toward greater interest in rural practice).

Differences and similarities between behavior of Fukushima-derived and Chernobyl-derived radiocesium in the environment

NASA Astrophysics Data System (ADS)

Konoplev, Alexei; Nanba, Kenji; Onda, Yuichi; Golosov, Valentin; Wakiyama, Yoshifumi; Takase, Tsugiko; Yoschenko, Vasyl; Zheleznyak, Mark

2016-04-01

The mobility and bioavailability of radiocesium (r-Cs) of accidental origin is governed by the ratio of its chemical forms in fallout and site-specific environmental characteristics determining the rates of leaching, fixation-remobilization, as well as sorption-desorption of the mobile fraction (its solid-liquid distribution). R-Cs in the environment is strongly bound to soil and sediment particles containing micaceous clay minerals (illite, vermiculite, etc.). This is associated with two basic processes - high selective reversible sorption and fixation. Climate and geographical conditions for Fukushima Prefecture of Japan and Chernobyl zone differ. For example, the catchments of the Chernobyl zone are flat and characterized by low slopes, while Fukushima's watersheds are hilly with steep slopes. Annual precipitation also differs substantially, with annual average for Fukushima about 3 times higher than at Chernobyl. The soils on the north-east coast of the Honshu island that were primarily affected by the radioactive contamination from the Fukushima Daiichi nuclear power plant (FDNPP) accident differ significantly from the Chernobyl zone soils. The proportion of clays such as illite, vermiculite etc. is 20-30% at Fukushima, which is higher than in the sandy loam soils of the Chernobyl zone. In addition to the landscape differences, the speciation of r-Cs in fallout was also different between Fukushima and Chernobyl. It is a challenge to compare r-Cs behavior in FDNPP and Chernobyl zones. Comparative analysis has been carried out for r-Cs wash-off parameters and the distribution coefficient Kd in rivers and surface runoff on Fukushima and Chernobyl contaminated areas for the first years after the accidents. The r-Cs distribution coefficient in Fukushima rivers was 1-2 orders of magnitude higher than correspondent values for rivers and surface runoff of the Chernobyl zone. This suggests higher ability of Fukushima soils and sediments to bind r-Cs. The normalized dissolved wash-off coefficients for Fukushima river watersheds are 1-2 orders of magnitude lower than corresponding values for the Chernobyl zone. Normalized particulate wash-off coefficients are comparable for Fukushima and Chernobyl. The effective dispersion coefficients in the Fukushima soils were found to be relatively high (2-10 cm2/year) as compared to Chernobyl values. Investigation and analysis of Fukushima-derived r-Cs distribution in soils of Niida river catchment has led to identify accumulation zones of contaminated sediments on the floodplain. Contaminated sediment accumulation is one of the most important factors for predicting r-Cs redistribution on a catchment and its fluvial transport, and is also relevant for decision making on remediation options of contaminated territories.

Mapping sequence performed during the STS-121 R-Bar Pitch Maneuver

NASA Image and Video Library

2006-07-06

ISS013-E-47629 (6 July 2006) --- A close-up view of Space Shuttle Discovery's tail section is featured in this image photographed by an Expedition 13 crewmember on the International Space Station during STS-121 R-Pitch Maneuver survey on Flight Day 3. Visible are the shuttle's main engines, vertical stabilizer, orbital maneuvering system (OMS) pods, reaction control system (RCS) jets and a portion of payload bay door radiator and wings.

Indicators for tracking programmes to strengthen health research capacity in lower- and middle-income countries: a qualitative synthesis

PubMed Central

2014-01-01

Background The monitoring and evaluation of health research capacity strengthening (health RCS) commonly involves documenting activities and outputs using indicators or metrics. We sought to catalogue the types of indicators being used to evaluate health RCS and to assess potential gaps in quality and coverage. Methods We purposively selected twelve evaluations to maximize diversity in health RCS, funders, countries, and approaches to evaluation. We explored the quality of the indicators and extracted them into a matrix across individual, institutional, and national/regional/network levels, based on a matrix in the ESSENCE Planning, Monitoring and Evaluation framework. We synthesized across potential impact pathways (activities to outputs to outcomes) and iteratively checked our findings with key health RCS evaluation stakeholders. Results Evaluations varied remarkably in the strengths of their evaluation designs. The validity of indicators and potential biases were documented in a minority of reports. Indicators were primarily of activities, outputs, or outcomes, with little on their inter-relationships. Individual level indicators tended to be more quantitative, comparable, and attentive to equity considerations. Institutional and national–international level indicators were extremely diverse. Although linkage of activities through outputs to outcomes within evaluations was limited, across the evaluations we were able to construct potential pathways of change and assemble corresponding indicators. Conclusions Opportunities for improving health RCS evaluations include work on indicator measurement properties and development of indicators which better encompass relationships with knowledge users. Greater attention to evaluation design, prospective indicator measurement, and systematic linkage of indicators in keeping with theories of change could provide more robust evidence on outcomes of health RCS. PMID:24725961

Immunohistochemical evaluation of inducible nitric oxide synthase in the epithelial lining of odontogenic cysts: A qualitative and quantitative analysis.

PubMed

Akshatha, B K; Karuppiah, Karpagaselvi; Manjunath, G S; Kumarswamy, Jayalakshmi; Papaiah, Lokesh; Rao, Jyothi

2017-01-01

The three common odontogenic cysts include radicular cysts (RCs), dentigerous cysts (DCs), and odontogenic keratocysts (OKCs). Among these 3 cysts, OKC is recently been classified as benign keratocystic odontogenic tumor attributing to its aggressive behavior, recurrence rate, and malignant potential. The present study involved qualitative and quantitative analysis of inducible nitric oxide synthase (iNOS) expression in epithelial lining of RCs, DCs, and OKCs, compare iNOS expression in epithelial linings of all the 3 cysts and determined overexpression of iNOS in OKCs which might contribute to its aggressive behavior and malignant potential. The present study is to investigate the role of iNOS in the pathogenesis of OKCs, DCs, and RCs by evaluating the iNOS expression in the epithelial lining of these cysts. Analysis of iNOS expression in epithelial lining cells of 20 RCs, 20 DCs, and 20 OKCs using immunohistochemistry done. The percentage of positive cells and intensity of stain was assessed and compared among all the 3 cysts using contingency coefficient. Kappa statistics for the two observers were computed for finding interobserver agreement. The percentage of iNOS-positive cells was found to be remarkably high in OKCs (12/20) -57.1% as compared to RCs (6/20) - 28.6% and DCs (3/20) - 14.3%. The interobserver agreement for iNOS-positive percentage cells was arrived with kappa values with OKCs → Statistically significant ( P > 0.000), RCs → statistically significant ( P > 0.001) with no significant values for DCs. No statistical difference exists among 3 study samples in regard to the intensity of staining with iNOS. Increased iNOS expression in OKCs may contribute to bone resorption and accumulation of wild-type p53, hence, making OKCs more aggressive.

Improvement of semi-quantitative small-animal PET data with recovery coefficients: a phantom and rat study.

PubMed

Aide, Nicolas; Louis, Marie-Hélène; Dutoit, Soizic; Labiche, Alexandre; Lemoisson, Edwige; Briand, Mélanie; Nataf, Valérie; Poulain, Laurent; Gauduchon, Pascal; Talbot, Jean-Noël; Montravers, Françoise

2007-10-01

To evaluate the accuracy of semi-quantitative small-animal PET data, uncorrected for attenuation, and then of the same semi-quantitative data corrected by means of recovery coefficients (RCs) based on phantom studies. A phantom containing six fillable spheres (diameter range: 4.4-14 mm) was filled with an 18F-FDG solution (spheres/background activity=10.1, 5.1 and 2.5). RCs, defined as measured activity/expected activity, were calculated. Nude rats harbouring tumours (n=50) were imaged after injection of 18F-FDG and sacrificed. The standardized uptake value (SUV) in tumours was determined with small-animal PET and compared to ex-vivo counting (ex-vivo SUV). Small-animal PET SUVs were corrected with RCs based on the greatest tumour diameter. Tumour proliferation was assessed with cyclin A immunostaining and correlated to the SUV. RCs ranged from 0.33 for the smallest sphere to 0.72 for the largest. A sigmoidal correlation was found between RCs and sphere diameters (r(2)=0.99). Small-animal PET SUVs were well correlated with ex-vivo SUVs (y=0.48x-0.2; r(2)=0.71) and the use of RCs based on the greatest tumour diameter significantly improved regression (y=0.84x-0.81; r(2)=0.77), except for tumours with important necrosis. Similar results were obtained without sacrificing animals, by using PET images to estimate tumour dimensions. RC-based corrections improved correlation between small-animal PET SUVs and tumour proliferation (uncorrected data: Rho=0.79; corrected data: Rho=0.83). Recovery correction significantly improves both accuracy of small-animal PET semi-quantitative data in rat studies and their correlation with tumour proliferation, except for largely necrotic tumours.

Optical Coherence Tomography of Retinal Degeneration in Royal College of Surgeons Rats and Its Correlation with Morphology and Electroretinography

PubMed Central

Yamauchi, Kodai; Mounai, Natsuki; Tanabu, Reiko; Nakazawa, Mitsuru

2016-01-01

Purpose To evaluate the correlation between optical coherence tomography (OCT) and the histological, ultrastructural and electroretinography (ERG) findings of retinal degeneration in Royal College of Surgeons (RCS-/-) rats. Materials and Methods Using OCT, we qualitatively and quantitatively observed the continual retinal degeneration in RCS-/- rats, from postnatal (PN) day 17 until PN day 111. These findings were compared with the corresponding histological, electron microscopic, and ERG findings. We also compared them to OCT findings in wild type RCS+/+ rats, which were used as controls. Results After PN day 17, the hyperreflective band at the apical side of the photoreceptor layer became blurred. The inner segment (IS) ellipsoid zone then became obscured, and the photoreceptor IS and outer segment (OS) layers became diffusely hyperreflective after PN day 21. These changes correlated with histological and electron microscopic findings showing extracellular lamellar material that accumulated in the photoreceptor OS layer. After PN day 26, the outer nuclear layer became significantly thinner (P < 0.01) and hyperreflective compared with that in the controls; conversely, the photoreceptor IS and OS layers, as well as the inner retinal layers, became significantly thicker (P < 0.001 and P = 0.05, respectively). The apical hyperreflective band, as well as the IS ellipsoid zone, gradually disappeared between PN day 20 and PN day 30; concurrently, the ERG a- and b-wave amplitudes deteriorated. In contrast, the thicknesses of the combined retinal pigment epithelium and choroid did not differ significantly between RCS-/- and RCS+/+ rats. Conclusion Our results suggest that OCT demonstrates histologically validated photoreceptor degeneration in RCS rats, and that OCT findings partly correlate with ERG findings. We propose that OCT is a less invasive and useful method for evaluating photoreceptor degeneration in animal models of retinitis pigmentosa. PMID:27644042

Benzodiazepine and kainate receptor binding sites in the RCS rat retina.

PubMed

Stasi, Kalliopi; Naskar, Rita; Thanos, Solon; Kouvelas, Elias D; Mitsacos, Ada

2003-02-01

The effect of age and photoreceptor degeneration on the kainate subtype of glutamate receptors and on the benzodiazepine-sensitive gamma-aminobutyric acid-A receptors (GABA(A)) in normal and RCS (Royal College of Surgeons) rats were investigated. [(3)H]Kainate and [(3)H]flunitrazepam were used as radioligands for kainate and GABA(A)/benzodiazepine()receptors, respectively, using the quantitative receptor autoradiography technique. In both normal and RCS rat retina we observed that [(3)Eta]flunitrazepam and [(3)Eta]kainate binding levels were several times higher in inner plexiform layer (IPL) than in outer plexiform layer (OPL) at all four ages studied (P17, P35, P60 and P180). Age-related changes in receptor binding were observed in normal rat retina: [(3)Eta]flunitrazepam binding showed a significant decrease of 25% between P17 and P60 in IPL,and [(3)Eta]kainate binding showed significant decreases between P17 and P35 in both synaptic layers (71% in IPL and 63% in OPL). Degeneration-related changes in benzodiazepine and kainate receptor binding were observed in RCS rat retina. In IPL, [(3)Eta]flunitrazepam and [(3)Eta]kainate binding levels were higher than in normal retina at P35 (by 24% and 86%, respectively). In OPL, [(3)Eta]flunitrazepam binding was higher in RCS than in normal retina on P35 (74%) and also on P60 (62%). The results indicate that postnatal changes occur in kainate and benzodiazepine receptor binding sites in OPL and IPL of the rat retina up to 6 months of age. The data also suggest that the receptor binding changes observed in the RCS retina could be a consequence of the primary photoreceptor degeneration.

Serratia marcescens ShlA Pore-Forming Toxin Is Responsible for Early Induction of Autophagy in Host Cells and Is Transcriptionally Regulated by RcsB

PubMed Central

Di Venanzio, Gisela; Stepanenko, Tatiana M.

2014-01-01

Serratia marcescens is a Gram-negative bacterium that thrives in a wide variety of ambient niches and interacts with an ample range of hosts. As an opportunistic human pathogen, it has increased its clinical incidence in recent years, being responsible for life-threatening nosocomial infections. S. marcescens produces numerous exoproteins with toxic effects, including the ShlA pore-forming toxin, which has been catalogued as its most potent cytotoxin. However, the regulatory mechanisms that govern ShlA expression, as well as its action toward the host, have remained unclear. We have shown that S. marcescens elicits an autophagic response in host nonphagocytic cells. In this work, we determine that the expression of ShlA is responsible for the autophagic response that is promoted prior to bacterial internalization in epithelial cells. We show that a strain unable to express ShlA is no longer able to induce this autophagic mechanism, while heterologous expression of ShlA/ShlB suffices to confer on noninvasive Escherichia coli the capacity to trigger autophagy. We also demonstrate that shlBA harbors a binding motif for the RcsB regulator in its promoter region. RcsB-dependent control of shlBA constitutes a feed-forward regulatory mechanism that allows interplay with flagellar-biogenesis regulation. At the top of the circuit, activated RcsB downregulates expression of flagella by binding to the flhDC promoter region, preventing FliA-activated transcription of shlBA. Simultaneously, RcsB interaction within the shlBA promoter represses ShlA expression. This circuit offers multiple access points to fine-tune ShlA production. These findings also strengthen the case for an RcsB role in orchestrating the expression of Serratia virulence factors. PMID:24914224

Improved approach for electric vehicle rapid charging station placement and sizing using Google maps and binary lightning search algorithm

PubMed Central

Shareef, Hussain; Mohamed, Azah

2017-01-01

The electric vehicle (EV) is considered a premium solution to global warming and various types of pollution. Nonetheless, a key concern is the recharging of EV batteries. Therefore, this study proposes a novel approach that considers the costs of transportation loss, buildup, and substation energy loss and that incorporates harmonic power loss into optimal rapid charging station (RCS) planning. A novel optimization technique, called binary lightning search algorithm (BLSA), is proposed to solve the optimization problem. BLSA is also applied to a conventional RCS planning method. A comprehensive analysis is conducted to assess the performance of the two RCS planning methods by using the IEEE 34-bus test system as the power grid. The comparative studies show that the proposed BLSA is better than other optimization techniques. The daily total cost in RCS planning of the proposed method, including harmonic power loss, decreases by 10% compared with that of the conventional method. PMID:29220396

Improved approach for electric vehicle rapid charging station placement and sizing using Google maps and binary lightning search algorithm.

PubMed

Islam, Md Mainul; Shareef, Hussain; Mohamed, Azah

2017-01-01

The electric vehicle (EV) is considered a premium solution to global warming and various types of pollution. Nonetheless, a key concern is the recharging of EV batteries. Therefore, this study proposes a novel approach that considers the costs of transportation loss, buildup, and substation energy loss and that incorporates harmonic power loss into optimal rapid charging station (RCS) planning. A novel optimization technique, called binary lightning search algorithm (BLSA), is proposed to solve the optimization problem. BLSA is also applied to a conventional RCS planning method. A comprehensive analysis is conducted to assess the performance of the two RCS planning methods by using the IEEE 34-bus test system as the power grid. The comparative studies show that the proposed BLSA is better than other optimization techniques. The daily total cost in RCS planning of the proposed method, including harmonic power loss, decreases by 10% compared with that of the conventional method.

Controllable stearic acid crystal induced high hydrophobicity on cellulose film surface.

PubMed

He, Meng; Xu, Min; Zhang, Lina

2013-02-01

A novel, highly hydrophobic cellulose composite film (RCS) with biodegradability was fabricated via solvent-vaporized controllable crystallization of stearic acid in the porous structure of cellulose films (RC). The interface structure and properties of the composite films were investigated with wide-angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), FT-IR, solid-state (13)C NMR, water uptake, tensile testing, water contact angle, and biodegradation tests. The results indicated that the RCS films exhibited high hydrophobicity (water contact angle achieved to 145°), better mechanical properties in the humid state and lower water uptake ratio than RC. Interestingly, the stearic acid crystallization was induced by the pore wall of the cellulose matrix to form a micronano binary structure, resulting in a rough surface. The rough surface with a hierarchical structure containing micronanospace on the RCS film surface could trap abundant air, leading to the high hydrophobicity. Moreover, the RCS films were flexible, biodegradable, and low-cost, showing potential applications in biodegradable water-proof packaging.

Business Models, Vaccination Services, and Public Health Relationships of Retail Clinics: A Qualitative Study.

PubMed

Arthur, Bayo C; Fisher, Allison Kennedy; Shoemaker, Sarah J; Pozniak, Alyssa; Stokley, Shannon

2015-01-01

Despite the rapid growth of retail clinics (RCs), literature is limited in terms of how these facilities offer preventive services, particularly vaccination services. The purpose of this study was to obtain an in-depth understanding of the RC business model pertaining to vaccine offerings, profitability, and decision making. From March to June 2009, we conducted 15 interviews with key individuals from three types of organizations: 12 representatives of RC corporations, 2 representatives of retail hosts (i.e., stores in which the RCs are located), and 1 representative of an industry association. We analyzed interview transcripts qualitatively. Our results indicate that consumer demand and profitability were the main drivers in offering vaccinations. RCs in this sample primarily offered vaccinations to adults and adolescents, and they were not well integrated with local public health and immunization registries. Our findings demonstrate the potential for stronger linkages with public health in these settings. The findings also may help inform future research to increase patient access to vaccination services at RCs.

Flex Dynamics Avoidance Control of the NEA Scout Solar Sail Spacecraft's Reaction Control System

NASA Technical Reports Server (NTRS)

Heaton Andrew; Stiltner, Brandon; Diedrich, Benjamin; Becker, Christopher; Orphee, Juan

2017-01-01

The Attitude Control System (ACS) is developed for a Near Earth Asteroid (NEA) Scout mission using a solar sail. The NEA-Scout spacecraft is a 6U cubesat with an 86 square-meter solar sail. NEA Scout will launch on Space Launch System (SLS) Exploration Mission 1 (EM-1), currently scheduled to launch in 2018. The spacecraft will rendezvous with a target asteroid after a two year journey, and will conduct science imagery. The solar sail spacecraft ACS consists of three major actuating subsystems: a Reaction Wheel (RW) control system, a Reaction Control System (RCS), and an Adjustable Mass Translator (AMT) system. The three subsystems allow for a wide range of spacecraft attitude control capabilities, needed for the different phases of the NEA-Scout mission. Because the sail is a flexible structure, care must be taken in designing a control system to avoid exciting the structural modes of the sail. This is especially true for the RCS, which uses pulse actuated, cold-gas jets to control the spacecraft's attitude. While the reaction wheels can be commanded smoothly, the RCS jets are simple on-off actuators. Long duration firing of the RCS jets - firings greater than one second - can be thought of as step inputs to the spacecraft's torque. On the other hand, short duration firings - pulses on the order of 0.1 seconds - can be thought of as impulses in the spacecraft's torque. These types of inputs will excite the structural modes of the spacecraft, causing the sail to oscillate. Sail oscillations are undesirable for many reasons. Mainly, these oscillations will feed into the spacecraft attitude sensors and pointing accuracy, and long term oscillations may be undesirable over the lifetime of the solar sail. In order to limit the sail oscillations, an RCS control scheme is being developed to minimize sail excitations. Specifically, an input shaping scheme similar to the method described in Reference 1 will be employed. A detailed description of the RCS control scheme will be provided with particular emphasis on flexible body excitation. The RCS performance will be provided to show that sail and boom excitation is minimized.

Prospects for low wing-loading STOL transports with ride smoothing.

NASA Technical Reports Server (NTRS)

Holloway, R. B.; Thompson, G. O.; Rohling, W. J.

1972-01-01

Airplanes with low wing-loadings provide STOL capability without reliance on auxiliary propulsion or augmented lift, but require a ride smoothing control system to provide acceptable passenger comfort. A parametric study produced a configuration having a .35 thrust-to-weight ratio and a 50 psf wing loading, and which satisfied specified mission requirements and airworthiness standards. A ride-smoothing control system (RCS) synthesis was then performed which consisted of ride quality criteria definition, RCS concept trades, and analysis of RCS performance benefits at significant flight conditions. Within the limitations of the study it is concluded that this is a viable approach to STOL airplane design.

Measurement of Ultra Wideband Radar Cross Sections of an Automobile at Ka Band Using Circular Polarizations

NASA Astrophysics Data System (ADS)

Osaki, Hideyuki; Nishide, Takehiko; Kobayashi, Takehiko

Ultra wideband (UWB) radar cross sections (RCSs) of several targets have been measured using various combinations of transmitting and receiving linear polarizations (V-V, H-H, and +45°--45°) with a view to obtaining information on the design of vehicular short-range radars. This paper reports the UWB RCSs (σLR and σLL) of a typical passenger automobile using two circular polarization combinations (L and R denote left and right circular polarizations). The wideband measurements were carried out with use of a vector network analyzer by sweeping the frequency from 24.5 to 28.8GHz in a radio anechoic chamber. The UWB RCSs were derived by integrating the received power in the frequency domain. Similar to the linear polarization results, fluctuations of the RCSs were smaller in the UWB than in narrowband for both L-R and L-L, because the ultra-wide bandwidth cancels out RCS plunges caused by narrowband interference among reflected waves from various facets of the target. The median of (σLR-σLL) was 2dB, while the median of (σHH-σ+45°--45°) or (σVV-σ+45°--45°) was 6dB. This is because the body of the automobile comprises a number of smaller scattering objects yielding σLL, either similar to the corner reflectors or asymmetrical to the radar boresight. Frequency-domain responses showed a number of notches caused by the interference between numerous reflecting waves having power levels of a similar order and different round-trip path lengths. Some representative reflective parts of the automobile were identified through analyses of time-domain responses.

Peak picking NMR spectral data using non-negative matrix factorization.

PubMed

Tikole, Suhas; Jaravine, Victor; Rogov, Vladimir; Dötsch, Volker; Güntert, Peter

2014-02-11

Simple peak-picking algorithms, such as those based on lineshape fitting, perform well when peaks are completely resolved in multidimensional NMR spectra, but often produce wrong intensities and frequencies for overlapping peak clusters. For example, NOESY-type spectra have considerable overlaps leading to significant peak-picking intensity errors, which can result in erroneous structural restraints. Precise frequencies are critical for unambiguous resonance assignments. To alleviate this problem, a more sophisticated peaks decomposition algorithm, based on non-negative matrix factorization (NMF), was developed. We produce peak shapes from Fourier-transformed NMR spectra. Apart from its main goal of deriving components from spectra and producing peak lists automatically, the NMF approach can also be applied if the positions of some peaks are known a priori, e.g. from consistently referenced spectral dimensions of other experiments. Application of the NMF algorithm to a three-dimensional peak list of the 23 kDa bi-domain section of the RcsD protein (RcsD-ABL-HPt, residues 688-890) as well as to synthetic HSQC data shows that peaks can be picked accurately also in spectral regions with strong overlap.

Equilibration kinetics in isolated and membrane-bound photosynthetic reaction centers upon illumination: a method to determine the photoexcitation rate.

PubMed

Manzo, Anthony J; Goushcha, Alexander O; Barabash, Yuri M; Kharkyanen, Valery N; Scott, Gary W

2009-07-01

Kinetics of electron transfer, following variation of actinic light intensity, for photosynthetic reaction centers (RCs) of purple bacteria (isolated and membrane-bound) were analyzed by measuring absorbance changes in the primary photoelectron donor absorption band at 865 nm. The bleaching of the primary photoelectron donor absorption band in RCs, following a sudden increase of illumination from the dark to an actinic light intensity of I(exp), obeys a simple exponential law with the rate constant alphaI(exp) + k(rec), in which alpha is a parameter relating the light intensity, measured in mW/cm(2), to a corresponding theoretical rate in units of reciprocal seconds, and k(rec) is the effective rate constant of the charge recombination in the photosynthetic RCs. In this work, a method for determining the alpha parameter value is developed and experimentally verified for isolated and membrane-bound RCs, allowing for rigorous modeling of RC macromolecule dynamics under varied photoexcitation conditions. Such modeling is necessary for RCs due to alterations of the forward photoexcitation rates and relaxation rates caused by illumination history and intramolecular structural dynamics effects. It is demonstrated that the classical Bouguer-Lambert-Beer formalism can be applied for the samples with relatively low scattering, which is not necessarily the case with strongly scattering media or high light intensity excitation.

Blood substitutes: how close to a solution?

PubMed

Klein, H G

2005-01-01

The term "blood substitute" is commonly misused when "red cell substitute (RCS) is meant. The ideal RCS should deliver (i) oxygen; (ii) require no compatibility testing; (iii) cause few side effects; (iv) have prolonged storage qualities; (v) persist in the circulation and (vi) be available at reasonable cost. While no drug with all these qualities is on the near horizon, several early generation RCS are approaching submission for licensing, at least for limited indications. Haemoglobin-derived RCS from human, bovine and recombinant sources, as well as perfluorochemicals that dissolve 02 are in different stages of development. While each formulation has its own physical characteristics, biological activities, and adverse reaction profile, all share one characteristic: the physiological consequences of delivering 02 with small molecules is poorly understood and may both account for problems seen in the clinical trials and provide therapeutic opportunities for the cancer patient. Those RCS in phase III trials all have a half-life measured in hours and are unlikely to replace transfusions or drugs that stimulate erythropoiesis for chronic anaemia, but they may play a role (i) in military and civilian trauma as resuscitation solutions, (ii) as a bridge to transfusion when no compatible blood is immediately available, (iii) as an adjunct to the autologous haemodilution management of surgery, or even (iv) in radiation therapy or the management of cancer-related vascular occlusive syndromes.

Application of a high-throughput relative chemical stability assay to screen therapeutic protein formulations by assessment of conformational stability and correlation to aggregation propensity.

PubMed

Rizzo, Joseph M; Shi, Shuai; Li, Yunsong; Semple, Andrew; Esposito, Jessica J; Yu, Shenjiang; Richardson, Daisy; Antochshuk, Valentyn; Shameem, Mohammed

2015-05-01

In this study, an automated high-throughput relative chemical stability (RCS) assay was developed in which various therapeutic proteins were assessed to determine stability based on the resistance to denaturation post introduction to a chaotrope titration. Detection mechanisms of both intrinsic fluorescence and near UV circular dichroism (near-UV CD) are demonstrated. Assay robustness was investigated by comparing multiple independent assays and achieving r(2) values >0.95 for curve overlays. The complete reversibility of the assay was demonstrated by intrinsic fluorescence, near-UV CD, and biologic potency. To highlight the method utility, we compared the RCS assay with differential scanning calorimetry and dynamic scanning fluorimetry methodologies. Utilizing C1/2 values obtained from the RCS assay, formulation rank-ordering of 12 different mAb formulations was performed. The prediction of long-term stability on protein aggregation is obtained by demonstrating a good correlation with an r(2) of 0.83 between RCS and empirical aggregation propensity data. RCS promises to be an extremely useful tool to aid in candidate formulation development efforts based on the complete reversibility of the method to allow for multiple assessments without protein loss and the strong correlation between the C1/2 data obtained and accelerated stability under stressed conditions. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Measuring self-regulation in a physically active context: Psychometric analyses of scores derived from an observer-rated measure of self-regulation.

PubMed

Lakes, Kimberley D

2013-10-01

The purpose of this study is to report psychometric properties of scores obtained using a novel observer-rated measure of children's self-regulation, the Response to Challenge Scale (RCS). The RCS was developed to rate children's self-regulatory abilities in a physically active context (e.g., while completing a physical challenge course). The RCS and other study measures were administered in a private school sample of 207 children. Analyses of score distributions indicated that the RCS was able to capture variance among children in self-regulatory abilities; the distribution was normal for the Affective, Cognitive, and Total Self-Regulation scales. Validity analyses revealed significant positive correlations between Cognitive, Affective, Motor, and Total Self-Regulation and executive function task performance; significant negative correlations between Cognitive Regulation and teacher-rated hyperactivity and inattention; significant negative correlations between Affective, Motor, and Total Self-Regulation and teacher ratings of peer problems; and significant positive correlations between Cognitive and Affective Regulation and parent ratings of prosocial behavior. Parent and teacher rated Total Difficulties scores were both negatively correlated with RCS Total Self-Regulation scores. Results suggest that it is possible for observers to rate self-regulatory abilities in the context of physical activities, and that these ratings correspond with performance on tasks requiring executive function as well as teacher and parent ratings of children's difficulties.

Light-evoked currents in retinal ganglion cells from dystrophic RCS rats.

PubMed

Liu, Kang; Wang, Yi; Yin, Zhengqin; Weng, Chuanhuang

2013-01-01

To study the electrophysiological properties of the light-evoked currents in ganglion cells in situations of retinal degeneration. We investigated light-evoked currents in ganglion cells by performing whole-cell patch-clamp recordings from ganglion cells using a retina-stretched preparation from Royal College of Surgeons (RCS) rats, a model of retinal degeneration and congenic controls at different ages. Pharmacological inhibitors of the AMPA receptor (NBQX), GABA receptor (BMI), and sodium channels (TTX) were used to identify the components of the light-evoked currents in ON, OFF and ON-OFF retinal ganglion cells. We found that the light-evoked currents in ganglion cells from control rats were inhibited by NBQX, BMI and TTX, suggesting that AMPA receptors, GABA receptors and sodium channels contribute to these currents in ganglion cells. However, only AMPA receptor-mediated currents were recorded in RCS rats. Light-evoked inward currents were absent in the majority of ganglion cells from RCS rats, particularly at the later stages of retinal degeneration. At earlier stages of retinal degeneration, we found that both the timing and amplitude of light-evoked currents are significantly different in ganglion cells from RCS and control rats. Our study furthers the understanding of the electrophysiological characteristics of retinal ganglion cells during retinal degeneration, and provides insight into the optimal timing for the treatment of retinal degeneration. Copyright © 2013 S. Karger AG, Basel.

Expression of c-Jun and Bcl-2 family proteins in apoptotic photoreceptors of RCS rats.

PubMed

Katai, Naomichi; Yanagidaira, Tomoko; Senda, Nami; Murata, Toshinori; Yoshimura, Nagahisa

2006-01-01

To determine if c-Jun and Bcl-2 family proteins play a role in photoreceptor apoptosis in Royal College of Surgeons (RCS) rats. RCS and Sprague-Dawley rats were used. Cryosections of retinas harvested at various postnatal periods were immunostained with antibodies against c-Jun, Bcl-2, and Bax. Double staining with TdT-dUTP nick-end labeling (TUNEL) or propidium iodide (PI) and antibodies was also done. To study the time course of gene and protein expression, semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and immunoblotting analyses were carried out. TUNEL-positive photoreceptors of RCS rats were stained strongly with antibodies against c-Jun and Bax. The number of immunoreactive cells increased on days 21 and 28 after birth (P21 and P28) and decreased on P45. Semiquantitative RT-PCR analysis showed that mRNAs for c-Jun and Bax were upregulated at P21 and P28, but those for Bcl-2 were unchanged. On immunoblotting, a 43-kDa band was revealed by the anti-c-Jun antibody and a 21-kDa band, by the anti-Bax antibody. Protein expression of c-Jun and Bax were increased at both P21 and P28. The temporal profiles of immunoreactivity, protein expression, and mRNA expression were similar. c-Jun and Bax may play a role in photoreceptor apoptosis in RCS rats.

Biogenesis of outer membrane vesicles in Serratia marcescens is thermoregulated and can be induced by activation of the Rcs phosphorelay system.

PubMed

McMahon, Kenneth J; Castelli, Maria E; García Vescovi, Eleonora; Feldman, Mario F

2012-06-01

Outer membrane vesicles (OMVs) have been identified in a wide range of bacteria, yet little is known of their biogenesis. It has been proposed that OMVs can act as long-range toxin delivery vectors and as a novel stress response. We have found that the formation of OMVs in the gram-negative opportunistic pathogen Serratia marcescens is thermoregulated, with a significant amount of OMVs produced at 22 or 30°C and negligible quantities formed at 37°C under laboratory conditions. Inactivation of the synthesis of the enterobacterial common antigen (ECA) resulted in a hypervesiculation phenotype, supporting the hypothesis that OMVs are produced in response to stress. We demonstrate that the phenotype can be reversed to wild-type (WT) levels upon the loss of the Rcs phosphorelay response regulator RcsB, but not RcsA, suggesting a role for the Rcs phosphorelay in the production of OMVs. MS fingerprinting of the OMVs provided evidence of cargo selection within wild-type cells, suggesting a possible role for Serratia OMVs in toxin delivery. In addition, OMV-associated cargo proved toxic upon injection into the haemocoel of Galleria mellonella larvae. These experiments demonstrate that OMVs are the result of a regulated process in Serratia and suggest that OMVs could play a role in virulence.

76 FR 40937 - Biweekly Notice; Applications and Amendments to Facility Operating Licenses Involving No...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-12

... Generator Water Level High-High'' instrument setpoint and associated allowable value. The proposed change is... [Pressurized-Water Reactor] PWR Operability Requirements and Actions for RCS Leakage Instrumentation''. Basis... monitor is the containment atmospheric gaseous radiation monitor. The monitoring of RCS leakage is not a...

Genome-wide identification of genes regulated by the Rcs Phosphorelay system in Erwinia amylovora

USDA-ARS?s Scientific Manuscript database

The exopolysaccharide amylovoran is one of the major pathgenicity factors in Erwinia amylovora, the causal agent of fire blight of apples and pears. We have previously demonstrated that the RcsBCD phosphorelay system is essential for virulence by controlling amylovoran biosynthesis. We have also fou...

Tradition and Innovation in Russian Church Slavonic Hymnography

ERIC Educational Resources Information Center

Nelson, Elena Margaret

2010-01-01

The focus of this dissertation is the highly specialized and stylized liturgical language of Russian Church Slavonic (RCS). Historically, RCS has been strictly controlled by authorities and has conformed to established norms, but innovations have nevertheless arisen in response to various conditions. One major wave of innovations was a long,…

Effects of replacing wild rye, corn silage, or corn grain with CaO-treated corn stover and dried distillers grains with solubles in lactating cow diets on performance, digestibility, and profitability.

PubMed

Shi, H T; Li, S L; Cao, Z J; Wang, Y J; Alugongo, G M; Doane, P H

2015-10-01

The objective of this study was to measure the effects of partially replacing wild rye (Leymus chinensis; WR), corn silage (CS), or corn grain (CG) in dairy cow diets with CaO-treated corn stover (T-CS) and corn dried distillers grains with soluble (DDGS) on performance, digestibility, blood metabolites, and income over feed cost. Thirty tonnes of air-dried corn stover was collected, ground, and mixed with 5% CaO. Sixty-four Holstein dairy cows were blocked based on days in milk, milk yield, and parity and were randomly assigned to 1 of 4 treatments. The treatments were (1) a diet containing 50% concentrate, 15% WR, 25% CS, and 10% alfalfa hay (CON); (2) 15% WR, 5% CG, and 6% soybean meal were replaced by 15% T-CS and 12% DDGS (RWR); (3) 12.5% CS, 6% CG, and 5% soybean meal were replaced by 12.5% T-CS and 12%DDGS (RCS); (4) 13% CG and 6% soybean meal were replaced by 7% T-CS and 13% DDGS (RCG). Compared with CON treatment, cows fed RCS and RCG diets had similar dry matter intake (CON: 18.2 ± 0.31 kg, RCS: 18.6 ± 0.31 kg, and RCG: 18.4 ± 0.40 kg). The RWR treatment tended to have lower dry matter intake than other treatments. The inclusion of T-CS and DDGS in treatment diets as a substitute for WR, CS, or CG had no effects on lactose percentage (CON: 4.96 ± 0.02%, RWR: 4.97 ± 0.02%, RCS: 4.96 ± 0.02%, and RCG: 4.94 ± 0.02%), 4% fat-corrected milk yield (CON: 22.7 ± 0.60 kg, RWR: 22.1 ± 0.60 kg, RCS: 22.7 ± 0.60 kg, and RCG: 22.7 ± 0.60 kg), milk fat yield (CON: 0.90 ± 0.03 kg, RWR: 0.86 ± 0.03 kg, RCS: 0.87 ± 0.03 kg, and RCG: 0.89 ± 0.03 kg), and milk protein yield (CON: 0.74 ± 0.02 kg, RWR: 0.72 ± 0.02 kg, RCS: 0.73 ± 0.02 kg, and RCG: 0.71 ± 0.02 kg). Cows fed the RWR diet had higher apparent dry matter digestibility (73.7 ± 1.30 vs. 70.2 ± 1.15, 69.9 ± 1.15, and 69.9 ± 1.15% for RWR vs. CON, RCS, and RCG, respectively) and lower serum urea N (3.55 ± 0.11 vs. 4.03 ± 0.11, 3.95 ± 0.11, and 3.99 ± 0.11 mmol/L for RWR vs. CON, RCS, and RCG, respectively) than cows fed other diets. No significant differences were noted in apparent neutral detergent fiber digestibility among the treatments. Compared with CON treatment, the RWR, RCS, and RCG treatments generated an additional $0.77, $0.70, and $0.81 income over feed cost per cow per day, respectively. In conclusion, feeding diets containing a portion of T-CS and DDGS can improve profitability of the treatment groups without negatively affecting the lactation performance of mid- to late-lactation cows. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A Flight Control Approach for Small Reentry Vehicles

NASA Technical Reports Server (NTRS)

Bevacqoa, Tim; Adams, Tony; Zhu. J. Jim; Rao, P. Prabhakara

2004-01-01

Flight control of small crew return vehicles during atmospheric reentry will be an important technology in any human space flight mission undertaken in the future. The control system presented in this paper is applicable to small crew return vehicles in which reaction control system (RCS) thrusters are the only actuators available for attitude control. The control system consists of two modules: (i) the attitude controller using the trajectory linearization control (TLC) technique, and (ii) the reaction control system (RCS) control allocation module using a dynamic table-lookup technique. This paper describes the design and implementation of the TLC attitude control and the dynamic table-lookup RCS control allocation for nonimal flight along with design verification test results.

RI/MOM and RI/SMOM renormalization of overlap quark bilinears on domain wall fermion configurations

NASA Astrophysics Data System (ADS)

Bi, Yujiang; Cai, Hao; Chen, Ying; Gong, Ming; Liu, Keh-Fei; Liu, Zhaofeng; Yang, Yi-Bo; χ QCD Collaboration

2018-05-01

Renormalization constants (RCs) of overlap quark bilinear operators on 2 +1 -flavor domain wall fermion configurations are calculated by using the RI/MOM and RI/SMOM schemes. The scale independent RC for the axial vector current is computed by using a Ward identity. Then the RCs for the quark field and the vector, tensor, scalar, and pseudoscalar operators are calculated in both the RI/MOM and RI/SMOM schemes. The RCs are converted to the MS ¯ scheme and we compare the numerical results from using the two intermediate schemes. The lattice size is 4 83×96 and the inverse spacing 1 /a =1.730 (4 ) GeV .

Impact of the residential conservation service program on natural gas and electric utilities. Appendix B

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

An assessment of the RCS program is provided from the perspective of eleven case study utilities. First, an introduction to the role and value of conservation in utility strategic planning is presented. The interplay of various utility system characteristics is shown to be the primary determinant of the value of conservation efforts from the utility's point of view. Simplified typologies of utilities are developed to aid in the identification of those combinations of the utility characteristics that will favor the adoption of the utility sponsored strategic conservation efforts. The integration of the RCS program with other utility conservation and loadmore » management programs is explored for the eleven case study utilities. Reference is made to the simplified typologies in order to show, through actual program experience, how the strategic position of the utility company affects its adoption of this federal program. Evaluative studies done by the eleven case study utilities of the RCS program are reviewed. Results are presented and the methodologies are critiqued. Conclusions regarding the RCS program from the utility perspective are presented.« less

Effects of nano-SiO{sub 2} particles on surface tracking characteristics of silicone rubber composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yong, E-mail: tjuliuyong@tju.edu.cn; Li, Zhonglei; Du, Boxue

Compared with neat silicone rubber composites (SiRCs), SiRCs filled with nano-sized SiO{sub 2} particles at weight ratios from 0.1 to 1.0 wt. % exhibit a higher surface flashover voltage and a greater resistance to surface tracking. Scanning electron microscopy images of tracking morphologies indicate that the SiO{sub 2} particles are situated in close proximity to the polymeric chains and act as bridges to stabilize the chains and maintain the structure of the composite. Higher concentrations of nano-sized SiO{sub 2} particles, however, (above 0.3 wt. %) produce defects in the molecular network which lead to reductions in both the surface flashover voltage and the resistancemore » to surface tracking, although these reduced values are still superior to those of neat SiRCs. Therefore, SiRCs filled with nano-sized SiO{sub 2} particles, especially at an optimal weight ratio (0.1 to 0.3 wt. %), may have significant potential applications as outdoor insulators for power systems.« less

Immunoexpression of vascular endothelial growth factor in periapical granulomas, radicular cysts, and residual radicular cysts.

PubMed

Nonaka, Cassiano Francisco Weege; Maia, Alexandre Pinto; Nascimento, George João Ferreira do; de Almeida Freitas, Roseana; Batista de Souza, Lélia; Galvão, Hébel Cavalcanti

2008-12-01

Our aim was to assess and compare the immunoexpression of vascular endothelial growth factor (VEGF) in periapical granulomas (PGs), radicular cysts (RCs), and residual radicular cysts (RRCs), relating it to the angiogenic index and the intensity of the inflammatory infiltrate. Twenty PGs, 20 RCs, and 10 RRCs were evaluated by immunohistochemistry using anti-VEGF antibody. Angiogenic index was determined by microvessel count (MVC) using anti-von Willebrand factor antibody. The PGs and RCs showed higher expression of VEGF than the RRCs. Lesions presenting few inflammatory infiltrate revealed the lowest immunoexpression of VEGF (P < .05). Irrespective of the intensity of the inflammatory infiltrate, most of the RCs and RRCs showed moderate to strong epithelial expression of VEGF. Lesions showing dense inflammatory infiltrate presented higher MVC indices (P < .05). VEGF expression and MVC did not reveal a significant correlation (P > .05). VEGF is present in periapical inflammatory lesions but at a lower level in RRCs. The expression of this proangiogenic factor is closely related to the intensity of the inflammatory infiltrate in these lesions.

Neuroprotective Dose Response in RCS Rats Implanted with Microphotodiode Arrays

PubMed Central

Pardue, Machelle T.; Kim, Moon K.; Walker, Tiffany A.; Faulkner, Amanda E.; Chow, Alan Y.; Ciavatta, Vincent T.

2012-01-01

Purpose Neuropreservation of retinal function and structure in RCS rats following implantation of a microphotodiode array (MPA) has been shown in previous studies(Pardue et al. 2005a; Pardue et al. 2005b). Since microphotodiodes produce electrical currents in proportion to the intensity of incident light, increased light exposure may result in greater neuroprotective effects. Our previous studies suggested that the frequency of light exposure to electroretinogram (ERG) flash stimuli might provide increased neuroprotection. Thus, in this study, we examined the dose response of subretinal electrical stimulation by exposing RCS rats implanted with MPAs to variable durations and combinations of two different lighting regimens: pulsing incandescent bulbs and xenon stimuli from an ERG Ganzfeld. While incandescent light regimens did not produce any significant differences in ERG function, we found significantly greater dark-adapted ERG b-wave amplitudes in RCS rats that received weekly versus biweekly ERGs over the course of 8 weeks of follow-up. These results suggest that subretinal electrical stimulation may be optimized to produce greater neuroprotective effects by dosing with periodic higher current. PMID:22183323

Intraocular gene transfer of ciliary neurotrophic factor rescues photoreceptor degeneration in RCS rats.

PubMed

Huang, Shun-Ping; Lin, Po-Kang; Liu, Jorn-Hon; Khor, Chin-Ni; Lee, Yih-Jing

2004-01-01

Ciliary neurotrophic factor (CNTF) is known as an important factor in the regulation of retinal cell growth. We used both recombinant CNTF and an adenovirus carrying the CNTF gene to regulate retinal photoreceptor expression in a retinal degenerative animal, Royal College of Surgeons (RCS) rats. Cells in the outer nuclear layer of the retinae from recombinant-CNTF-treated, adenoviral-CNTF-treated, saline-operated, and contralateral untreated preparations were examined for those exhibiting CNTF photoreceptor protective effects. Cell apoptosis in the outer nuclear layer of the retinae was also detected. It was found that CNTF had a potent effect on delaying the photoreceptor degeneration process in RCS rats. Furthermore, adenovirus CNTF gene transfer was proven to be better at rescuing photoreceptors than that when using recombinant CNTF, since adenoviral CNTF prolonged the photoreceptor protection effect. The function of the photoreceptors was also examined by taking electroretinograms of different animals. Adenoviral-CNTF-treated eyes showed better retinal function than did the contralateral control eyes. This study indicates that adenoviral CNTF effectively rescues degenerating photoreceptors in RCS rats. Copyright 2004 National Science Council, ROC and S. Karger AG, Basel

Robotic cardiac surgery in Brazil

PubMed Central

Toschi, Alisson P.; Pope, Renato B.; Montanhesi, Paola K.; Santos, Ricardo S.; Teruya, Alexandre; Hatanaka, Dina M.; Rusca, Gabriel F.; Fischer, Claudio H.; Vieira, Marcelo C.; Makdisse, Marcia R.

2017-01-01

Background Brazil, the largest country and economy in South America, is a major driving force behind the development of new medical technologies in the region. Robotic cardiac surgery (RCS) has been evolving rapidly since 2010, when the first surgery using the DaVinci® robotic system was performed in Latin America. The aim of this article is to evaluate short and mid-term results in patients undergoing robotic cardiac surgery in Brazil. Methods From March 2010 to December 2015, 39 consecutive patients underwent robotic cardiac surgery. Twenty-seven patients were male (69.2%), with the mean age of 51.3±17.9 years. Participants had a mean ejection fraction of 62±5%. The procedures included in this study were mitral valve surgery, surgical treatment of atrial fibrillation, atrial septal defect closure, resection of intra-cardiac tumors, totally endoscopic coronary artery bypass and pericardiectomy. Results The mean time spent on cardiopulmonary bypass (CPB) during RCS was 154.9±94.2 minutes and the mean aortic cross-clamp time was 114.48±75.66 minutes. Thirty-two patients (82%) were extubated in the operating room immediately after surgery. The median intensive care unit (ICU) length of stay was 1 day (ranging from 0 to 25) and the median hospital length of stay was 5 days (ranging from 3 to 25). For each type of procedure, endpoints were individually reported. There were no conversions to sternotomy and no intra-operative complications. Patient follow-up was complete in 100% of the participants, with two early deaths unrelated to the procedures and no re-operations at mid-term. Conclusions Despite the heterogeneity of this series, RCS appears to be feasible, safe and effective when used for the correction of various intra- and extra-cardiac pathologies. Adopting the robotic system has been a challenge in Brazil, where its limited clinical application may be related to the lack of specific training and the high cost of technology. PMID:28203537

Robotic cardiac surgery in Brazil.

PubMed

Poffo, Robinson; Toschi, Alisson P; Pope, Renato B; Montanhesi, Paola K; Santos, Ricardo S; Teruya, Alexandre; Hatanaka, Dina M; Rusca, Gabriel F; Fischer, Claudio H; Vieira, Marcelo C; Makdisse, Marcia R

2017-01-01

Brazil, the largest country and economy in South America, is a major driving force behind the development of new medical technologies in the region. Robotic cardiac surgery (RCS) has been evolving rapidly since 2010, when the first surgery using the DaVinci ® robotic system was performed in Latin America. The aim of this article is to evaluate short and mid-term results in patients undergoing robotic cardiac surgery in Brazil. From March 2010 to December 2015, 39 consecutive patients underwent robotic cardiac surgery. Twenty-seven patients were male (69.2%), with the mean age of 51.3±17.9 years. Participants had a mean ejection fraction of 62±5%. The procedures included in this study were mitral valve surgery, surgical treatment of atrial fibrillation, atrial septal defect closure, resection of intra-cardiac tumors, totally endoscopic coronary artery bypass and pericardiectomy. The mean time spent on cardiopulmonary bypass (CPB) during RCS was 154.9±94.2 minutes and the mean aortic cross-clamp time was 114.48±75.66 minutes. Thirty-two patients (82%) were extubated in the operating room immediately after surgery. The median intensive care unit (ICU) length of stay was 1 day (ranging from 0 to 25) and the median hospital length of stay was 5 days (ranging from 3 to 25). For each type of procedure, endpoints were individually reported. There were no conversions to sternotomy and no intra-operative complications. Patient follow-up was complete in 100% of the participants, with two early deaths unrelated to the procedures and no re-operations at mid-term. Despite the heterogeneity of this series, RCS appears to be feasible, safe and effective when used for the correction of various intra- and extra-cardiac pathologies. Adopting the robotic system has been a challenge in Brazil, where its limited clinical application may be related to the lack of specific training and the high cost of technology.

REACTIVE CARBONYL SPECIES AND THEIR ROLES IN SARCOPLASMIC RETICULUM Ca2+ CYCLING DEFECT IN THE DIABETIC HEART

PubMed Central

Tian, Chengju; Alomar, Fadhel; Moore, Caronda J; Shao, Chun Hong; Kutty, Shelby; Singh, Jaipaul; Bidasee, Keshore R.

2016-01-01

Efficient and rhythmic cardiac contractions depend critically on the adequate and synchronized release of Ca2+ from the sarcoplasmic reticulum (SR) via ryanodine receptor Ca2+ release channels (RyR2) and its reuptake via sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA2a). It is well established that this orchestrated process becomes compromised in diabetes. What remain incompletely defined are the molecular mechanisms responsible for the dysregulation of RyR2 and SERCA2a in diabetes. Earlier, found elevated levels of carbonyl adducts on RyR2 and SERCA2a isolated from hearts of type 1 diabetic rats and showed the presence of these post-translational modifications compromised their functions. We also showed that these mono- and di-carbonyl reactive carbonyl species (RCS) do not indiscriminately react with all basic amino acid residues on RyR2 and SERCA2a; some residues are more susceptible to carbonylation (modification by RCS) than others. A key unresolved question in the field is which of the many RCS that are upregulated in the heart in diabetes chemically react with RyR2 and SERCA2a? This brief review introduces readers to the field of RCS and their roles in perturbing SR Ca2+ cycling in diabetes. It also provides new experimental evidence that not all RCS that are upregulated in the heart in diabetes chemically react with RyR2 and SERCA2a, methylglyoxal and glyoxal preferentially do. PMID:23430128

Stomatin-Like Protein 2 Is Required for In Vivo Mitochondrial Respiratory Chain Supercomplex Formation and Optimal Cell Function

PubMed Central

Mitsopoulos, Panagiotis; Chang, Yu-Han; Wai, Timothy; König, Tim; Dunn, Stanley D.; Langer, Thomas

2015-01-01

Stomatin-like protein 2 (SLP-2) is a mainly mitochondrial protein that is widely expressed and is highly conserved across evolution. We have previously shown that SLP-2 binds the mitochondrial lipid cardiolipin and interacts with prohibitin-1 and -2 to form specialized membrane microdomains in the mitochondrial inner membrane, which are associated with optimal mitochondrial respiration. To determine how SLP-2 functions, we performed bioenergetic analysis of primary T cells from T cell-selective Slp-2 knockout mice under conditions that forced energy production to come almost exclusively from oxidative phosphorylation. These cells had a phenotype characterized by increased uncoupled mitochondrial respiration and decreased mitochondrial membrane potential. Since formation of mitochondrial respiratory chain supercomplexes (RCS) may correlate with more efficient electron transfer during oxidative phosphorylation, we hypothesized that the defect in mitochondrial respiration in SLP-2-deficient T cells was due to deficient RCS formation. We found that in the absence of SLP-2, T cells had decreased levels and activities of complex I-III2 and I-III2-IV1-3 RCS but no defects in assembly of individual respiratory complexes. Impaired RCS formation in SLP-2-deficient T cells correlated with significantly delayed T cell proliferation in response to activation under conditions of limiting glycolysis. Altogether, our findings identify SLP-2 as a key regulator of the formation of RCS in vivo and show that these supercomplexes are required for optimal cell function. PMID:25776552

In vitro biocorrosion of Ti-6Al-4V implant alloy by a mouse macrophage cell line.

PubMed

Lin, Hsin-Yi; Bumgardner, Joel D

2004-03-15

Corrosion of implant alloys releasing metal ions has the potential to cause adverse tissue reactions and implant failure. We hypothesized that macrophage cells and their released reactive chemical species (RCS) affect the alloy's corrosion properties. A custom cell culture corrosion box was used to evaluate how cell culture medium, macrophage cells and RCS altered the Ti-6Al-4V corrosion behaviors in 72 h and how corrosion products affected the cells. There was no difference in the charge transfer in the presence (75.2 +/- 17.7 mC) and absence (62.3 +/- 18.8 mC) of cells. The alloy had the lowest charge transfer (28.2 +/- 4.1 mC) and metal ion release (Ti < 10 ppb, V < 2 ppb) with activated cells (releasing RCS) compared with the other two conditions. This was attributed to an enhancement of the surface oxides by RCS. Metal ion release was very low (Ti < 20 ppb, V < 10 ppb) with nonactivated cells and did not change cell morphology, viability, and NO and ATP release compared with controls. However, IL-1beta released from the activated cells and the proliferation of nonactivated cells were greater on the alloy than the controls. In summary, macrophage cells and RCS reduced the corrosion of Ti-6Al-4V alloys as hypothesized. These data are important in understanding host tissue-material interactions. Copyright 2004 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 717-724, 2004

Accumulation of neurocan, a brain chondroitin sulfate proteoglycan, in association with the retinal vasculature in RCS rats.

PubMed

Zhang, Yiqin; Rauch, Uwe; Perez, Maria-Thereza R

2003-03-01

To examine whether and how the retinal distribution of the chondroitin sulfate proteoglycan neurocan is affected after photoreceptor cell loss and whether it correlates with the multiple secondary cellular changes that accompany the photoreceptor degeneration. Retinas from normal rats (Sprague-Dawley; postnatal days [P]0-P70), RCS rats with dystrophic retinas (P0-P300), RCS-rdy(+) congenic rats with nondystrophic retinas (P0-202), and rhodopsin mutant rats, P23H (P0-P257) and S334ter (P0-P220), were processed for immunohistochemistry using a polyclonal antibody to rat neurocan. The overall distribution of neurocan was similar in all retinas examined. Neurocan immunostaining was detected over the nerve fiber layer, the plexiform layers, the photoreceptor outer segments region, and the ciliary epithelium. With age, labeling throughout the plexiform layers decreased continuously. In RCS rats however, conspicuous labeling was also seen in association with retinal vessels, from P15 onward. Accumulation of neurocan in association with the retinal vasculature does not correlate with photoreceptor cell loss, because it was not observed in the rhodopsin mutant rats. During the earliest stages of the disease, accumulation of debris in the subretinal space in RCS rats may be sufficient per se to initiate a cascade of metabolic changes that result in accumulation of neurocan. With time, the neurocan accumulated perivascularly may, by interaction with other matrix molecules, modulate at least some of the vascular alterations observed in this animal model.

Radical Chemistry and Structural Relationships of PPCP Degradation by UV/Chlorine Treatment in Simulated Drinking Water.

PubMed

Guo, Kaiheng; Wu, Zihao; Shang, Chii; Yao, Bo; Hou, Shaodong; Yang, Xin; Song, Weihua; Fang, Jingyun

2017-09-19

The UV/chlorine process is an emerging advanced oxidation process (AOP) used for the degradation of micropollutants. However, the radical chemistry of this AOP is largely unknown for the degradation of numerous structurally diverse micropollutants in water matrices of varying quality. These issues were addressed by grouping 34 pharmaceuticals and personal care products (PPCPs) according to the radical chemistry of their degradation in the UV/chlorine process at practical PPCP concentrations (1 μg L -1 ) and in different water matrices. The contributions of HO • and reactive chlorine species (RCS), including Cl • , Cl 2 •- , and ClO • , to the degradation of different PPCPs were compound specific. RCS showed considerable reactivity with olefins and benzene derivatives, such as phenols, anilines, and alkyl-/alkoxybenzenes. A good linear relationship was found between the RCS reactivity and negative values of the Hammett ∑σ p + constant for aromatic PPCPs, indicating that electron-donating groups promote the attack of benzene derivatives by RCS. The contribution of HO • , but not necessarily RCS, to PPCP removal decreased with increasing pH. ClO • showed high reactivity with some PPCPs, such as carbamazepine, caffeine, and gemfibrozil, with second-order rate constants of 9.2 × 10 7 , 1.03 × 10 8 , and 4.16 × 10 8 M -1 s -1 , respectively, which contributed to their degradation. Natural organic matter (NOM) induced significant scavenging of ClO • and greatly decreased the degradation of PPCPs that was attributable to ClO • , with a second-order rate constant of 4.5 × 10 4 (mg L -1 ) -1 s -1 . Alkalinity inhibited the degradation of PPCPs that was primarily attacked by HO • and Cl • but had negligible effects on the degradation of PPCPs by ClO • . This is the first study on the reactivity of RCS, particularly ClO • , with structurally diverse PPCPs under simulated drinking water condition.