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1

Design, Fabrication and Testing of an Infrared Ratio Pyrometer System for the Measurement of Gasifier Reaction Chamber Temperature  

SciTech Connect

Texaco was awarded contract DE-FC26-99FT40684 from the U.S. DOE to design, build, bench test and field test an infrared ratio pyrometer system for measuring gasifier temperature. The award occurred in two phases. Phase 1, which involved designing, building and bench testing, was completed in September 2000, and the Phase 1 report was issued in March 2001. Phase 2 was completed in 2005, and the results of the field test are contained in this final report. Two test campaigns were made. In the first one, the pyrometer was sighted into the gasifier. It performed well for a brief period of time and then experienced difficulties in keeping the sight tube open due to a slag accumulation which developed around the opening of the sight tube in the gasifier wall. In the second test campaign, the pyrometer was sighted into the top of the radiant syngas cooler through an unused soot blower lance. The pyrometer experienced no more problems with slag occlusions, and the readings were continuous and consistent. However, the pyrometer readings were 800 to 900 F lower than the gasifier thermocouple readings, which is consistent with computer simulations of the temperature distribution inside the radiant syngas cooler. In addition, the pyrometer readings were too sluggish to use for control purposes. Additional funds beyond what were available in this contract would be required to develop a solution that would allow the pyrometer to be used to measure the temperature inside the gasifier.

Tom Leininger

2005-03-31

2

DESIGN, FABRICATION AND BENCH TESTING OF A TEXACO INFRARED RATIO PYROMETER SYSTEM FOR THE MEASUREMENT OF GASIFIER REACTION CHAMBER TEMPERATURE  

SciTech Connect

ChevronTexaco has shipped the pyrometer system to Tampa, Florida. Polk Power is in the process of installing the mechanical, electrical and instrumentation of the pyrometer system as well as integrating the instrumentation to the test site Distributed Control System. The startup and field testing of the system will begin afterwards.

Thomas F. Leininger; Hua-Min Huang

2004-01-01

3

DESIGN, FABRICATION AND BENCH TESTING OF A TEXACO INFRARED RATIO PYROMETER SYSTEM FOR THE MEASUREMENT OF GASIFIER REACTION CHAMBER TEMPERATURE  

SciTech Connect

Polk Power and ChevronTexaco have signed the cooperative agreement at the end of reporting period. ChevronTexaco is shipping the pyrometer system to Tampa, Florida. Polk Power will start the modification fieldwork and installation of the system. The testing will start when the next opportunity is available.

Thomas F. Leininger; Hua-Min Huang

2003-10-01

4

DESIGN, FABRICATION, ASSEMBLY AND BENCH TESTING OF A TEXACO INFRARED RATIO PYROMETER SYSTEM FOR THE MEASUREMENT OF REACTION CHAMBER TEMPERATURE  

SciTech Connect

Reliable measurement of gasifier reaction chamber temperature is important for the proper operation of slagging, entrained-flow gasification processes. Historically, thermocouples have been used as the main measurement technique, with the temperature inferred from syngas methane concentration being used as a backup measurement. While these have been sufficient for plant operation in many cases, both techniques suffer from limitations. The response time of methane measurements is too slow to detect rapid upset conditions, and thermocouples are subject to long-term drift, as well as slag attack, which eventually leads to failure of the thermocouple. Texaco's Montebello Technology Center (MTC) has developed an infrared ratio pyrometer system for measuring gasifier reaction chamber temperature. This system has a faster response time than both methane and thermocouples, and has been demonstrated to provide reliable temperature measurements for longer periods of time when compared to thermocouples installed in the same MTC gasifier. In addition, the system can be applied to commercial gasifiers without any significant scale-up issues. The major equipment items, the purge system, and the safety shutdown system in a commercial plant are essentially identical to the prototypes at MTC. The desired result of this DOE program is ''a bench-scale prototype, either assembled or with critical components (laboratory) tested in a convincing manner.'' The prototype of the pyrometer system (including gasifier optical access port) that was designed, assembled and tested for this program, has had previous prototypes that have been built and successfully tested under actual coal and coke gasification conditions in three pilot units at MTC. It was the intent of the work performed under the auspices of this program to review and update the existing design, and to fabricate and bench test an updated system that can be field tested in one or more commercial gasifiers during a follow on phase of this program. For all intents and purposes, the development, bench testing and pilot unit testing of this temperature measurement system has already been done, and was mostly a matter of getting the hardware ready for a commercial field test. The benefits of field-testing are (1) Texaco will gain long-term commercial operating experience and (2) commercial gasifier operators will gain confidence that this system can perform reliably under true commercial plant conditions. This work was performed by Texaco at its Montebello Technology Center in South El Monte, California.

Tom Leininger

2001-03-31

5

Pyrometer system for monitoring the particle impact on a substrate during a plasma spray process  

Microsoft Academic Search

A measurement system consisting of two high-speed two-colour pyrometers is described; the system is suitable for monitoring the flattening and cooling of particles on a substrate during plasma spray deposition. The first double-wavelength optical fibre pyrometer is focused 2 mm before the substrate and the other is focused on the substrate surface. The present instrument provides data on the temperature,

M. Vardelle; A. Vardelle; P. Fauchais; C. Moreau

1994-01-01

6

Development of a Multi-Point Pyrometer System (MPPS) for measuring surface temperature and emissivity  

SciTech Connect

In support of the US DOE MHD research program, the Diagnostic Instrumentation and Analysis Laboratory (DIAL) has been actively engaged in developing and applying advanced optical diagnostic techniques and instrumentation systems to high temperature coal-fired gas streams for over a decade. One of the earliest diagnostic systems developed by DIAL was a two color pyrometer (TCP). In this system, two commercial single-color pyrometers and a microprocessor system were used to form a TCP which can make accurate measurements of surfaces of unknown emissivity and temperature. This system has been used extensively to make measurements in support of the national MHD program. This report describes this system.

Benton, R.D.; Jang, Ping-Rey

1993-06-01

7

Optical pyrometer system for collisionless shock experiments in high-power laser-produced plasmas  

SciTech Connect

A temporally and spatially resolved optical pyrometer system has been fielded on Gekko XII experiments. The system is based on the self-emission measurements with a gated optical imager (GOI) and a streaked optical pyrometer (SOP). Both detectors measure the intensity of the self-emission from laser-produced plasmas at the wavelength of 450 nm with a bandpass filter with a width of {approx}10 nm in FWHM. The measurements were calibrated with different methods, and both results agreed with each other within 30% as previously reported [T. Morita et al., Astrophys. Space Sci. 336, 283 (2011)]. As a tool for measuring the properties of low-density plasmas, the system is applicable for the measurements of the electron temperature and density in collisionless shock experiments [Y. Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011)].

Morita, T.; Sakawa, Y.; Kuramitsu, Y.; Sano, T.; Takabe, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Dono, S.; Ide, T.; Tanji, H.; Shiroshita, A. [Graduate School of Engineering, Osaka University, 1-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Shibata, S.; Aoki, H. [Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan); Waugh, J. N.; Woolsey, N. C. [Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Gregory, C. D. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, Route de Saclay, 91128 Palaiseau (France)

2012-10-15

8

Improvements to the three-color optical CCD-based pyrometer system  

SciTech Connect

We put forward an improved three-color measurement scheme with a color CCD sensor using the combination of effective wavelengths and blackbody calibrations. The process of effective wavelengths realizes the separation of the emissivity function from the measurement integral equation. This improved method not only effectively avoids errors arising from the traditional process adopting the basic wavelengths, but also simplifies the complex integral calculations. For a blackbody or graybody, the measurement performance of the pyrometer was experimentally investigated from the point of the temperature sensitivity. The results show that narrowing the spectrum bandwidth with different bandpass spectral filters may improve the temperature sensitivities. The spectrum adjustment not only makes the linear emissivity more suitable in the narrower waveband, but also reduces the numerical uncertainty of the effective wavelengths. For nongray objects, the effects of the numerical uncertainty of the effective wavelengths to measurements were quantificationally evaluated at different measurement conditions (different temperatures, emissivities, and spectrums). The results indicate that the reference values of 584, 555, and 511nm or 607, 560, and 506nm of the effective wavelengths are reasonable for the present system with the modified spectral response using Filter 1 or Filter 2. The maximum calculation errors arising from the reference effective wavelengths are less than 1.6%. In this paper, the technical realization steps of the improved method are also described. The measurement experiments of a metal sample in hot environments were carried out to further verify the applicability of this improved CCD-based pyrometer. The results agreed well with the spectrometer-based results.

Fu Tairan; Zhao Huan; Zeng Jun; Wang Zhe; Zhong Maohua; Shi Congling

2010-11-01

9

Measurement of turbine blade temperature using pyrometer  

NASA Astrophysics Data System (ADS)

This paper presents the study of application of a self-made turbine blade pyrometer to measuring rotating turbine blade temperatures in a bed testing aeroengine. The study includes the temperature measuring principle and the pyrometer system; installation and adjustment of the double ball-floating type configuration optical head which goes through four different high temperatures bulkheads; and measurement of three kinds of temperature (the average blade temperature Ta, the average peak blade temperature Tap, and the maximum peak blade temperature Tmp) for all rotor blades of the turbine first stage. The experimental data analysis reveals that the first attempt of application of this pyrometer is successful. The measurement errors in the temperature range of 550-1200 C are within + or - 1 percent of calculated blade temperatures.

Cheng, H.; Du, C.

1985-09-01

10

Fast fiber-optic multi-wavelength pyrometer.  

PubMed

A fast fiber-optic multi-wavelength pyrometer was developed for the ultraviolet-visible-near infrared spectra from 200 nm to 1700 nm using a CCD detector and an InGaAs detector. The pyrometer system conveniently and quickly provides the sufficient choices of multiple measurement wavelengths using optical diffraction, which avoids the use of narrow-band filters. Flexible optical fibers are used to transmit the radiation so the pyrometer can be used for temperature measurements in harsh environments. The setup and calibrations (wavelength calibration, nonlinearity calibration, and radiation response calibration) of this pyrometer system were described. Development of the multi-wavelength pyrometer involved optimization of the bandwidth and temperature discrimination of the multiple spectra data. The analysis results showed that the wavelength intervals, ??(CCD) = 30 nm and ??(InGaAs) = 50 nm, are the suitable choices as a tradeoff between the simple emissivity model assumption and the multiple signal discrimination. The temperature discrimination was also quantificationally evaluated for various wavelengths and temperatures. The measurement performance of the fiber-optic multi-wavelength pyrometer was partially verified through measurements with a high-temperature blackbody and actual hot metals. This multi-wavelength pyrometer can be used for remote high-temperature measurements. PMID:21721719

Fu, Tairan; Tan, Peng; Pang, Chuanhe; Zhao, Huan; Shen, Yi

2011-06-01

11

Uncertainty of Pyrometers in a Casting Facility  

SciTech Connect

This work has established uncertainty limits for the EUO filament pyrometers, digital pyrometers, two-color automatic pyrometers, and the standards used to certify these instruments (Table 1). If symmetrical limits are used, filament pyrometers calibrated in Production have certification uncertainties of not more than {+-}20.5 C traceable to NIST over the certification period. Uncertainties of these pyrometers were roughly {+-}14.7 C before introduction of the working standard that allowed certification in the field. Digital pyrometers addressed in this report have symmetrical uncertainties of not more than {+-}12.7 C or {+-}18.1 C when certified on a Y-12 Standards Laboratory strip lamp or in a production area tube furnace, respectively. Uncertainty estimates for automatic two-color pyrometers certified in Production are {+-}16.7 C. Additional uncertainty and bias are introduced when measuring production melt temperatures. A -19.4 C bias was measured in a large 1987 data set which is believed to be caused primarily by use of Pyrex{trademark} windows (not present in current configuration) and window fogging. Large variability (2{sigma} = 28.6 C) exists in the first 10 m of the hold period. This variability is attributed to emissivity variation across the melt and reflection from hot surfaces. For runs with hold periods extending to 20 m, the uncertainty approaches the calibration uncertainty of the pyrometers. When certifying pyrometers on a strip lamp at the Y-12 Standards Laboratory, it is important to limit ambient temperature variation (23{+-}4 C), to order calibration points from high to low temperatures, to allow 6 m for the lamp to reach thermal equilibrium (12 m for certifications below 1200 C) to minimize pyrometer bias, and to calibrate the pyrometer if error exceeds vendor specifications. A procedure has been written to assure conformance.

Mee, D.K.; Elkins, J.E.; Fleenor, R.M.; Morrision, J.M.; Sherrill, M.W.; Seiber, L.E.

2001-12-07

12

Two-color optical charge-coupled-device-based pyrometer using a two-peak filter.  

PubMed

A two-color optical charge-coupled-device (CCD)-based pyrometer was developed using a multipeak interference filter with a color CCD sensor to measure multicolor signals with specified wavelengths. The effective and simple method adjusts the fixed spectrum response characteristics of a color CCD to allow improved temperature measurements. This pyrometer system not only has the advantage of traditional two-color (two-wavelength) pyrometry, but also overcomes the restrictions of color CCDs that can only be applied in waveband measurements. The measurement performance of the system using a two-peak filter (?(1)=643?nm,??(2)=564?nm) was evaluated by blackbody experiments. The results show that the low temperature detection limit is increased about 200 K with an increase in the sensitivity of the measured signals compared with the original system without two-peak filter [Fu, et al., Opt. Laser Technol. 42, 586 (2010)]. And the effective temperature range is also increased when T > 1233 K. The measured ratio C(R)/C(G) is monotonically relative to the temperature, which simplifies the measurements. The temperature sensitivity of 2.49 is larger and more uniform than the temperature sensitivity of 1.36 in the previous original system. Thus, the measurement performance of the new system is greatly improved. Finally, as an application, the surface temperature distribution of stainless steel sample in hot environments was determined by this new CCD-based pyrometer. The results agree well with the spectrometer-based results and further verify the applicability of the new system. PMID:21198043

Fu, Tairan; Zhao, Huan; Zeng, Jun; Zhong, Maohua; Shi, Congling

2010-12-01

13

DESIGN, FABRICATION AND BENCH TESTNG OF A TEXACO INFRARED RATIO PYROMETER SYSTEM FOR THE MEASUREMENT OF GASIFIER REACTION CHAMBER TEMPERATURE  

SciTech Connect

The cooperative agreement between Texaco and Polk Power has been revised by Polk Power and ChevronTexaco several times already. Lawyers from both Polk Power and ChevronTexaco are in the process to include the issues related to the ownership transfer of the Texaco gasification unit in the agreement and finalize the draft. The modification fieldwork and testing will start once the cooperative agreement is signed with Polk Power.

Thomas F. Leininger; Hua-Min Huang

2003-04-01

14

DESIGN, FABRICATION AND BENCH TESTING OF A TEXACO INFRARED RATIO PYROMETER SYSTEM FOR THE MEASUREMENT OF GASIFIER REACTION CHAMBER TEMPERATURE  

SciTech Connect

Polk Power has decided that the Texaco gasification unit will not be sold to a third party. Therefore, including the ownership transfer of the Texaco gasification unit in the agreement is not an issue any more. The cooperative agreement between Texaco and Polk Power has been revised several times in this quarter. Polk power is making comments on the last draft that Texaco sent to them. The modification fieldwork and testing will start once the cooperative agreement is signed with Polk Power.

Thomas F. Leininger; Hua-Min Huang

2003-07-01

15

Comparison of Two Pyrometers Used to Calibrate Primary Standards Laboratory's Tungsten Filament Lamps.  

National Technical Information Service (NTIS)

The Primary Standards Laboratory presently uses an automatic optical pyrometer with a photomultiplier tube photodetector to calibrate tungsten filament lamps. This pyrometer is compared to a newly designed direct optical pyrometer with a photodiode photod...

M. K. Odom

1987-01-01

16

Infrarot-Temperaturmessung Mit Selbsttaetiger Beruecksichtigung des Emissionsgrads (Infrared Temperature Measurement with Self Regulating Emission Ratio).  

National Technical Information Service (NTIS)

A temperature measuring procedure without contact, based on infrared radiation pyrometers is described. A self-regulating emission ratio multispectral pyrometer able to register three parameters related to the spectral composition of a non-black object: o...

V. Tank

1987-01-01

17

Comparison of two pyrometers used to calibrate Primary Standards Laboratory's tungsten filament lamps  

SciTech Connect

The Primary Standards Laboratory presently uses an automatic optical pyrometer with a photomultiplier tube photodetector to calibrate tungsten filament lamps. This pyrometer is compared to a newly designed direct optical pyrometer with a photodiode photodetector. Though the direct pyrometer looks promising, final improvements are necessary to make a conclusive comparison.

Odom, M.K.

1987-01-01

18

A high-speed four-channel infrared pyrometer  

SciTech Connect

A high-speed, four-wavelength pyrometer has been developed for dynamic temperature measurements on samples that are heated by shock compression. The pyrometer uses a pair of off-axis parabolic mirrors to collect radiance emitted from a target of 1 mm in diameter. A single optical fiber delivers the collected radiant flux to the detector housing. Three dichroic beam splitters are used to spectrally split the light into four beams that are then focused onto an equal number of LN2-cooled InSb photodetectors. Broad bandwidth interference filters that are nominally centered at 1.8, 2.4, 3.4, and 5.0 {micro}m define the wavelength ranges of the four channels. The blackbody-temperature threshold of the pyrometer is at about 400 K. The signals are recorded at intervals as short as 20 ns using a four-channel digital oscilloscope. Procedures for calibration and temperature measurements are described.

Boboridis, K.; Obst, A. W. (Andrew W.)

2002-01-01

19

Pyrometer model based on sensor physical structure and thermal operation  

Microsoft Academic Search

This paper proposes a new simplified thermal model for pyrometers, which takes into account both their internal and external physical structure and operation. The model is experimentally tested on the REMS GTS, an instrument for measuring ground temperature, which is part of the payload of the NASA MSL mission to Mars. The proposed model is based on an energy balance

Eduardo Sebastián; Carlos Armiens; Javier Gómez-Elvira

2010-01-01

20

Alternative calibration techniques for high-speed pyrometers in shock experiments  

NASA Astrophysics Data System (ADS)

Optical pyrometry is widely used in industry and research laboratories to perform surface temperature measurements of sample materials. These shock physics experiments are normally conducted at powder or gas gun facilities or at facilities where high explosives can be used as a shock wave source, and using high-speed pyrometers that are usually calibrated by using a blackbody source. But, electrical power, time, and space can be limiting factors in such facilities, and blackbody calibration can be difficult. Crucial parts of the experimental setup (fibers, lenses, and/or mirrors) are destroyed in such experiments, and the pyrometry system must be recalibrated before each experiment. We have developed a calibration technique using integrating-sphere sources that allows us to calibrate pyrometers more rapidly and easily than with blackbodies. Two different integrating-sphere systems are described to cover the wavelength range generally used in pyrometry studies. The characterization of these systems is fully detailed including measurements of their spectral radiances. A discussion of the advantages and drawbacks of both calibration sources is given.

Partouche-Sebban, D.; Holtkamp, D. B.; Rodriguez, P.; Stone, J. B.; Borror, S. D.; Kruschwitz, C. A.; Young, J. A.

2005-01-01

21

Filter Radiometers as a Tool for Quality Assurance of Temperature Measurements with Linear Pyrometers  

NASA Astrophysics Data System (ADS)

Measurements made with a pyrometer are vulnerable to errors if the pyrometer is misaligned, inaccurately characterized, or malfunctioning. In this work, thermodynamic temperatures between 1,373 and 1,773 K were studied by measuring a variable-temperature blackbody with a linear pyrometer and four absolutely characterized filter radiometers. The filter radiometer measurements were done in the irradiance mode. In the first set of measurements, there was a 3-5 K difference between the pyrometer and the filter radiometer data. The cause was tracked to malfunctioning of the pyrometer, which was afterwards sent for repair on the basis of these results. In the second set of measurements, with the repaired pyrometer, the agreement of the temperature results was good, the mean difference being -0.41 K with a standard deviation of 0.52 K. The differences between the pyrometer and the filter radiometer temperature measurement results showed no temperature dependence. It was concluded that the filter radiometers used in the irradiance mode provided a straightforward method for the quality assurance of pyrometers.

Ojanen, M.; Ahtee, V.; Noorma, M.; Weckström, T.; Kärhä, P.; Ikonen, E.

2008-06-01

22

Multiwavelength optical pyrometer for shock compression experiments.  

PubMed

A system for measurement of the spectral radiance of materials shocked to high pressures ( approximately 100 GPa) by impact using a light gas gun is described. Thermal radiation from the sample is sampled at six wavelength bands in the visible spectrum, and each signal is separately detected by solid-state photodiodes, and recorded with a time resolution of approximately 10 ns. Interpretation of the records in terms of temperature of transparent sample materials is discussed. Results of a series of exploratory experiments with metals are also given. Shock temperatures in the range 4000-8000 K have been reliably measured. Spectral radiance and temperatures have been determined with uncertainties of 2%. PMID:18699402

Lyzenga, G A; Ahrens, T J

1979-11-01

23

Air-fuel ratio control system  

Microsoft Academic Search

An air-fuel ratio control system for an internal combustion engine including an automobile carburetor having a fuel passage for forming a combustible air-fuel mixture by mixing fuel fed through the fuel passage with air drawn from the atmosphere, comprises a catalytic converter for substantially purifying exhaust gases emitted from the engine, a composition sensor for sensing the concentration of a

Matsuoka

1982-01-01

24

Application of a high speed, low temperature infrared pyrometer in pulsed power experiments  

NASA Astrophysics Data System (ADS)

A new, multichannel infrared (IR) pyrometer has been constructed that is capable of measuring low temperature changes (<100 °C) at high speed (multi-MHz). The pyrometer has four IR channels spanning 1-11 ?m and uses 1 mm optical fibers to relay the light from the center of a pulsed power experiment to the detectors. Broad IR passbands are used to increase sensitivity while preserving high accuracy in the temperature measurement (<15% for the absolute temperature (K) up to 1300 K). An application of the pyrometer in material property measurements of high strain at high strain rate is described.

Partouche-Sebban, David; Holtkamp, David B.; Bartsch, R. Richard; Lee, Huan; Schmitt, Gerald G.

2001-07-01

25

CO (Carbon Monoxide Mixing Ratio System) Handbook  

SciTech Connect

The main function of the CO instrument is to provide continuous accurate measurements of carbon monoxide mixing ratio at the ARM SGP Central Facility (CF) 60-meter tower (36.607 °N, 97.489 °W, 314 meters above sea level). The essential feature of the control and data acquisition system is to record signals from a Thermo Electron 48C and periodically calibrate out zero and span drifts in the instrument using the combination of a CO scrubber and two concentrations of span gas (100 and 300 ppb CO in air). The system was deployed on May 25, 2005.

Biraud, S

2011-02-23

26

Evaluation and comparison of three IR detectors and three amplifier designs for a new, high-speed IR pyrometer  

SciTech Connect

At Los Alamos National Laboratory (LANL), a high-speed, four-wavelength, infrared (IR) pyrometer has been used for surface temperature measurements in shock-physics experiments for several years. The pyrometer uses solid state detectors and a single fiber-optic cable for transmission of light from the target surface to the detectors. This instrument has recently been redesigned for an upcoming experiment at the Nevada Test Site (NTS). Three different IR detectors (two HgCdTe variants as well as the existing InSb chip) were compared for sensitivity, signal-to-noise ratio, and bandwidth. Of major concern was detector amplifier recovery time from overload saturation. In shock physics experiments, a short but very bright precursor frequently accompanies shock breakout (often from trapped air). This precursor can saturate the amplifier and may ''swamp-out'' the signal of interest before the amplifier recovers. With this in mind, we evaluated two new amplifier designs by the Perry Amplifier Company for linearity, signal-to-noise characteristics, gain, and saturation recovery time. This paper describes experimental setup for detector comparison and results obtained. Furthermore, we discuss new amplifier design and suitability for highspeed infrared pyrometry in shock physics experiments.

J.A. Young, S. Borrora, A.W. Obst, J.R. Payton, A. Seifter

2005-01-01

27

Flexible Conversion Ratio Fast Reactor Systems Evaluation  

SciTech Connect

Conceptual designs of lead-cooled and liquid salt-cooled fast flexible conversion ratio reactors were developed. Both concepts have cores reated at 2400 MWt placed in a large-pool-type vessel with dual-free level, which also contains four intermediate heat exchanges coupling a primary coolant to a compact and efficient supercritical CO2 Brayton cycle power conversion system. Decay heat is removed passively using an enhanced Reactor Vessel Auxiliary Cooling System and a Passive Secondary Auxiliary Cooling System. The most important findings were that (1) it is feasible to design the lead-cooled and salt-cooled reactor with the flexible conversion ratio (CR) in the range of CR=0 and CR=1 n a manner that achieves inherent reactor shutdown in unprotected accidents, (2) the salt-cooled reactor requires Lithium thermal Expansion Modules to overcme the inherent salt coolant's large positive coolant temperature reactivity coefficient, (3) the preferable salt for fast spectrum high power density cores is NaCl-Kcl-MgCl2 as opposed to fluoride salts due to its better themal-hydraulic and neutronic characteristics, and (4) both reactor, but attain power density 3 times smaller than that of the sodium-cooled reactor.

Neil Todreas; Pavel Hejzlar

2008-06-30

28

Thermal management in pyrometer modules for automotive applications  

NASA Astrophysics Data System (ADS)

Thermopile pyrometer modules are the state of the art for contactless temperature measurement in automotive applications. Here sensors have to operate precisely in a challenging thermal environment. While the compensation of the steady state ambient temperature is a well known technique in thermopile radiation temperature sensors, transient thermal effects are still an issue. The change of the ambient temperature as well as temperature flow through the sensor can lead to substantial errors due to unwanted thermal gradients within the device. In the thermopile chip they leads to an error signal since the measurement principle is based on quantifying thermal gradients of the chip that result from the detected IR-radiation. Thermal gradients in the cap and between cap and thermopile chip lead to an exchange of heat radiation between thermopile chip and cap that is erroneously detected and thus also leads to errors. Different methods were developed that separately or in combination allow for a significant improvement of the accuracy and signal stability. The methods are based on the reduction of thermal gradients within the thermopile chip and the entire sensor device (isothermal, high thermal mass cap), reduction of radiation exchange between the sensor chip and the housing (low emissive inner cap surface) and prediction and software compensation of the error signal.

Liess, Martin; Hausner, Martin; Ernst, Henrik; Karagözoglu, Hermann; Schilz, Jürgen

2006-05-01

29

Ratios  

NSDL National Science Digital Library

This "homework help" lesson introduces students to ratios, ratio language, equivalent ratios, and allows students to practice with a set of problems at the end. The lesson is divided into four parts: First Glance, In Depth, Examples, and Workout.

2005-01-01

30

Ratios  

NSDL National Science Digital Library

This set of instructional materials and problems helps students understand ratios and proportions, starting with a simple review and progressing into the more advanced territory of similar triangles. The first three pages introduce ratios, proportions, and checking proportionality and the last four pages present mathematical and real-world problems for students to solve given their understanding of ratios and proportions.

Stapel, Elizabeth

2000-01-01

31

Multi-channel optical pyrometer for sub-nanosecond temperature measurements at NDCX-I/II  

SciTech Connect

We present a detailed technical description of a fast multi-channel pyrometer designed for warm-dense-matter (WDM) experiments with intense heavy ion beams at the neutralized-drift-compression-experiment linear accelerator (NDCX-I/II) at Lawrence Berkeley National Laboratory (LBNL). The unique features of the described instrument are its sub-nanosecond temporal resolution (100 ps rise-time) and a broad range, 1,500 K - 12,000 K of measurable brightness temperatures in the visible and near-infrared regions of the spectrum. The working scheme, calibration procedure, experimental data obtained with the pyrometer and future applications are presented.

Ni, P.A.; Bieniosek, F.M.; Waldron, W.L.

2011-04-13

32

In-flight particle pyrometer for thermal spray processes. Final report, October 1, 1992--December 31, 1994  

SciTech Connect

The objective of the project was to produce an industrial hardened particle temperature sensor. In general the thermal spray community believes that the particle temperature and velocity prior to impact on the substrate are two of the predominant parameters which effect coating quality. Prior to the full scale prototyping of such an instrument it was necessary to firmly establish the relationship between operating parameters, particle temperature and coating characteristics. It was shown in the first year of this project that the characteristics and consistency of the coatings formed are directly determined by particle velocity and temperature at impact. For the HVOF spray process the authors have also shown that the particle velocity is determined primarily by chamber pressure, while stoichiometry (the ratio of oxygen to fuel) has a minor influence. Hence, particle velocity can be controlled by maintaining the chamber pressure at a set point. Particle temperature, on the other hand is primarily a function of stoichiometry. Therefore particle velocity and temperature can be independently controlled. In the second year (FY-94), an industrial hardened prototype particle temperature sensor (In-flight Particle Pyrometer) was produced. The IPP is a two-color radiation pyrometer incorporating improvements which make the device applicable to the measurement of in-flight temperature of particles over a wide range of operating conditions in thermal spray processes. The device is insensitive to particulate loading (particle feed rate), particle composition, particle size distribution, and provides an ensemble average particle temperature. The sensor head is compact and coupled to the electronics via a fiber optic cable. Fiber optic coupling allows maximum flexibility of deployment while providing isolation of the electronics from electromagnetic interference and the hot, particulate laden environment of a typical spray booth. The device is applicable to all thermal spray processes, including plasma spray, HVOF, twin wire arc, and liquid metal fed processes, as well as other more conventional high temperature processes such as crucible or hearth melting.

NONE

1995-02-20

33

Fast six-channel pyrometer for warm-dense-matter experiments with intense heavy-ion beams  

SciTech Connect

This paper describes a fast multi-channel radiation pyrometer that was developed for warmdense-matter experiments with intense heavy ion beams at Gesellschaft fur Schwerionenforschung mbH (GSI). The pyrometer is capable of measuring of brightness temperatures from 2000 K to 50000 K, at 6 wavelengths in visible and near-infrared parts of spectrum, with 5 nanosecond temporal resolution and several micrometers spatial resolution. The pyrometer's spectral discrimination technique is based on interference filters, which act as filters and mirrors to allow for simultaneous spectral discrimination of the same ray at multiple wavelengths.

Ni, P.A.; Kulish, M.I.; Mintsev, V.; Nikolaev, D.N.; Ternovoi, V.Ya.; Hoffmann, D.H.H.; Udrea, S.; Tahir, N.A.; Varentsov, D.; Hug, A.

2008-12-01

34

Elevated sacroilac joint uptake ratios in systemic lupus erythematosus  

SciTech Connect

Sacroiliac joint radiographs and radionuclide sacroiliac joint uptake ratios were obtained on 14 patients with active systemic lupus erythematosus. Elevated joint ratios were found unilaterally in two patients and bilaterally in seven patients when their lupus was active. In patients whose disease became quiescent, the uptake ratios returned to normal. Two patients had persistently elevated ratios with continued clinical and laboratory evidence of active lupus. Mild sacroiliac joint sclerosis and erosions were detected on pelvic radiographs in these same two patients. Elevated quantitative sacroiliac joint uptake ratios may occur as a manifestation of active systemic lupus erythematosus.

De Smet, A.A.; Mahmood, T.; Robinson, R.G.; Lindsley, H.B.

1984-08-01

35

Air to fuel ratio control system for internal combustion engine  

Microsoft Academic Search

An air to fuel ratio control system for an internal combustion engine having a fixed venturi type carburetor is disclosed. The air to fuel ratio control system comprises a device for extracting an atmospheric pressure within a venturi or a pressure corresponding to a relieved venturi vacuum, a device for extracting a static fuel pressure downstream of a main jet

Y. Nishimura; Y. Oyama

1980-01-01

36

High-speed two-camera imaging pyrometer for mapping fireball temperatures.  

PubMed

A high-speed imaging pyrometer was developed to investigate the behavior of flames and explosive events. The instrument consists of two monochrome high-speed Phantom v7.3 m cameras made by Vision Research Inc. arranged so that one lens assembly collects light for both cameras. The cameras are filtered at 700 or 900 nm with a 10 nm bandpass. The high irradiance produced by blackbody emission combined with variable shutter time and f-stop produces properly exposed images. The wavelengths were chosen with the expected temperatures in mind, and also to avoid any molecular or atomic gas phase emission. Temperatures measured using this pyrometer of exploded TNT charges are presented. PMID:22108886

Densmore, John M; Homan, Barrie E; Biss, Matthew M; McNesby, Kevin L

2011-11-20

37

Pyrometer mount for a closed-circuit thermal medium cooled gas turbine  

DOEpatents

A steam-cooled second-stage nozzle segment has an outer band and an outer cover defining a plenum therebetween for receiving cooling steam for flow through the nozzles to the inner band and cover therefor and return flow through the nozzles. To measure the temperature of the buckets of the stage forwardly of the nozzle stage, a pyrometer boss is electron beam-welded in an opening through the outer band and TIG-welded to the outer cover plate. By machining a hole through the boss and seating a linearly extending tube in the boss, a line of sight between a pyrometer mounted on the turbine frame and the buckets is provided whereby the temperature of the buckets can be ascertained. The welding of the boss to the outer band and outer cover enables steam flow through the plenum without leakage, while providing a line of sight through the outer cover and outer band to measure bucket temperature.

Jones, Raymond Joseph (Duanesburg, NY); Kirkpatrick, Francis Lawrence (late of Galway, NY); Burns, James Lee (Schenectady, NY); Fulton, John Robert (Clifton Park, NY)

2002-01-01

38

Evaluation and improvement in the accuracy of a charge-coupled-device-based pyrometer for temperature field measurements of continuous casting billets  

NASA Astrophysics Data System (ADS)

This paper presents a radiometric high-temperature field measurement model based on a charge-coupled-device (CCD). According to the model, an intelligent CCD pyrometer with a digital signal processor as the core is developed and its non-uniformity correction algorithm for reducing the differences in accuracy between individual pixel sensors is established. By means of self-adaptive adjustment for the light-integration time, the dynamic range of the CCD is extended and its accuracy in low-temperature range is improved. The non-uniformity correction algorithm effectively reduces the accuracy differences between different pixel sensors. The performance of the system is evaluated through a blackbody furnace and an integrating sphere, the results of which show that the dynamic range of 400 K is obtained and the accuracy in low temperature range is increased by 7 times compared with the traditional method based on the fixed light-integration time. In addition, the differences of accuracy between the on-axis pixel and the most peripheral pixels are decreased from 19.1 K to 2.8 K. Therefore, this CCD pyrometer ensures that the measuring results of all pixels tend to be equal-accuracy distribution across the entire measuring ranges. This pyrometric system has been successfully applied to the temperature field measurements in continuous casting billets.

Bai, Haicheng; Xie, Zhi; Zhang, Yuzhong; Hu, Zhenwei

2013-06-01

39

The Labor\\/Land Ratio and India's Caste System  

Microsoft Academic Search

This paper proposes that India's caste system and involuntary labor were joint responses by a nonworking landowning class to a low labor\\/land ratio in which the rules of the caste system supported the institution of involuntary labor. The hypothesis is tested in two ways: longitudinally, with data from ancient religious texts, and cross-sectionally, with twentieth-century statistics on regional population\\/land ratios

Harriet Duleep

2012-01-01

40

System and method for high precision isotope ratio destructive analysis  

DOEpatents

A system and process are disclosed that provide high accuracy and high precision destructive analysis measurements for isotope ratio determination of relative isotope abundance distributions in liquids, solids, and particulate samples. The invention utilizes a collinear probe beam to interrogate a laser ablated plume. This invention provides enhanced single-shot detection sensitivity approaching the femtogram range, and isotope ratios that can be determined at approximately 1% or better precision and accuracy (relative standard deviation).

Bushaw, Bruce A; Anheier, Norman C; Phillips, Jon R

2013-07-02

41

The evolution of sex ratios and sex-determining systems  

Microsoft Academic Search

Sex determination is a fundamental process governed by diverse mechanisms. Sex ratio selection is commonly implicated in the evolution of sex-determining systems, although formal models are rare. Here, we argue that, although sex ratio selection can induce shifts in sex determination, genomic conflicts between parents and offspringcanexplainwhysingle-factorsystems(e.g. XY\\/ XX or ZW\\/ZZ) are common even in species that experi- ence selection

Tobias Uller; Ido Pen; Erik Wapstra; Leo W. Beukeboom; Jan Komdeur

2007-01-01

42

High ratio long-wave infrared continuous zoom system  

NASA Astrophysics Data System (ADS)

As infrared zoom systems change the focal length continuously, remain images stability and keep good image quality during the process of zoom, it is widely applied to infrared navigation, infrared detection, infrared-guided etc vehicular and airborne area. In order to satisfy the growing demand of infrared continuous zoom system, a zoom ratio of ten times long-wave infrared continuous zoom optical system that based on an uncooled detector was designed. System guided by the zoom theory of positive groups of compensation, calculated the initial structure of the system and according to the system of optical parameters with using ZEMAX software for optical design did an aberration balance and optimized, then the optical system image quality was systematically analyzed and evaluated. The result showed that the modulation transfer function (MTF) was above 0.4 within the whole focal range at spatial frequency 16 lp/mm, the root mean square radius of maximum dispersion spot was smaller than a pixel dimension and it met the requirements of the system imaging quality when F/# was 2, continuous zoom range was from 40 mm to 400 mm and the image size was 12 mm. The design of the system realized the requirements of compact structure, large zoom ratio, easily assembled and excellent image quality to optical system for infrared imaging.

Yan, Jing; Sun, Quan; Liu, Ying; Zhou, Hao; Huan, Kewei; Shi, Xiao-guang

2013-09-01

43

Log-ratio technique for beam position monitor systems  

SciTech Connect

Recent progress in the development of a beam position monitor system (BPM), based on the log-ratio technique, is described in this paper. A complete electronic analysis is presented, showing linearity, dynamic range, noise, RF burst response, and temperature dependence. A calibration technique has been developed, which corrects the errors due to mismatched channels and electronics drift. This technique is particularly effective because of the log-ratio property for beam position monitoring. This circuit is the most likely candidate for beam position monitor electronics at the SSC.

Roberto Aiello, G.; Mills, M.R. (Superconducting Super Collider Laboratory, 2550 Beckleymeade Ave., Dallas, TX 75237 (United States))

1992-07-10

44

Revolution speed ratio control system for a continuously variable transmission  

SciTech Connect

This patient describes revolution speed ratio control system for a continuously variable transmission comprising a driving pulley provided on an input shaft; a driven pulley provided on an output shaft disposed in parallel with the input shaft; an endless belt wound on both the pulleys; each of the pulleys comprising a fixed member secured to the input or output shaft and having a conical surface, and a movable member which has a conical surface facing that of the fixed member and is provided so that the movable member is rotated together with the input or output shaft and can be slid on the shaft in the axial direction thereof; and the endless belt has both its oblique side surfaces frictionally engaged with the conical surfaces of the fixed and movable members; an electronic control circuit including a means for calculating the actual revolution speed ratio between the driving and driven pulleys of the transmission, a means for generating a first electric control signal corresponding to the difference between the actual revolution speed ratio and an aimed revolution speed ratio between the pulleys determined by information of the input torque of the input shaft and required torque for the output shaft, and a means for generating a second electric control signal determined by the sum of an electric signal corresponding to the actual revolution speed ratio and an electric signal corresponding to the difference; and a hydraulic control circuit including a pressure oil source, a first cylinder which is provided on the input shaft and supplied with working oil from the pressure oil source to push the movable member of the driving pulley toward the fixed member thereof.

Hattori, K.; Suzuki, H.; Yamaguchi, H.; Ogasawara, T.

1988-12-13

45

Decreased serum apolipoprotein AII/AI ratio in systemic amyloidosis  

PubMed Central

OBJECTIVE—To investigate if serum apolipoprotein A-I and A-II (apoAI and apoAII) concentrations change in subjects with systemic amyloidosis secondary to underlying disorders.?METHODS—Serum concentrations of apoAI and apoAII were measured in 21 multiple myeloma patients, including eight with amyloidosis; 95 rheumatoid arthritis patients, including 45 with amyloidosis; and 73 haemodialysis patients, including 32 with amyloidosis.?RESULTS—ApoAII values tended to be reduced in subjects with amyloidosis in each group, but could not effectively distinguish amyloidosis. However, apoAII/AI ratios were significantly lower in subjects with amyloidosis in all groups. The ratio of 0.2 had diagnostic sensitivity and specificity for amyloidosis; 50% and 100%, respectively, in multiple myeloma; 80% and 78%, respectively, in rheumatoid arthritis; and 46% and 90%, respectively, in patients requiring long term haemodialysis.?CONCLUSION—The apoAII/AI ratio can be a useful biochemical marker of suspect amyloidosis in patients with underlying diseases, especially those with rheumatoid arthritis.?? Keywords: amyloidosis; apolipoprotein; rheumatoid arthritis; haemodialysis

Yamada, T.; Ozawa, T.; Gejyo, F.; Okuda, Y.; Takasugi, K.; Hotta, O.; Itoh, Y.

1998-01-01

46

Measurements on flame temperature and its 3D distribution in a 660 MWe arch-fired coal combustion furnace by visible image processing and verification by using an infrared pyrometer  

NASA Astrophysics Data System (ADS)

In order to verify the 3D temperature distribution of combustion in large-scale, coal-fired boiler furnaces visualized through a visible flame image processing system, a carefully calibrated portable flame temperature measuring system adopting the same flame image processing technique was developed, which is more convenient for industrial flame measurements. Furthermore, the temperatures and emissivities measured by the portable system were compared with the results by an infrared pyrometer which was used to measure the equivalent blackbody temperatures of the flames. The relative differences of the predicted temperatures and emissivity for a blackbody furnace by the portable system are less than 1% and 3%, respectively, showing a good accuracy for its application in the combustion industry. The equivalent blackbody temperatures deduced from the flame temperatures and emissivities measured by the portable system from 12 flame-observing ports in a 660 MWe arch-fired boiler in three horizontal sections at different elevations were compared with those measured by the infrared pyrometer. The relative differences are less than 7%, an acceptable agreement for measurements in the case of a coal-fired furnace. The cross-section-averaged temperatures deduced from the 3D temperature distribution acquired by the visualizing system were verified by those measured by the portable flame measuring system, and the two sets of results matched each other reasonably. This revealed that the coal combustion in the furnace was suffering from seriously delayed ignition of coal, leading to a lower efficiency of fuel utilization.

Huajian, Wang; Zhifeng, Huang; Dundun, Wang; Zixue, Luo; Yipeng, Sun; Qingyan, Fang; Chun, Lou; Huaichun, Zhou

2009-11-01

47

Extreme oxygen isotope ratios in the early Solar System.  

PubMed

The origins of the building blocks of the Solar System can be studied using the isotopic composition of early planetary and meteoritic material. Oxygen isotopes in planetary materials show variations at the per cent level that are not related to the mass of the isotopes; rather, they result from the mixture of components having different nucleosynthetic or chemical origins. Isotopic variations reaching orders of magnitude in minute meteoritic grains are usually attributed to stellar nucleosynthesis before the birth of the Solar System, whereby different grains were contributed by different stars. Here we report the discovery of abundant silica-rich grains embedded in meteoritic organic matter, having the most extreme 18O/16O and 17O/16O ratios observed (both approximately 10(-1)) together with a solar silicon isotopic composition. Both O and Si isotopes indicate a single nucleosynthetic process. These compositions can be accounted for by one of two processes: a single exotic evolved star seeding the young Solar System, or irradiation of the circumsolar gas by high energy particles accelerated during an active phase of the young Sun. We favour the latter interpretation, because the observed compositions are usually not expected from nucleosynthetic processes in evolved stars, whereas they are predicted by the selective trapping of irradiation products. PMID:16163350

Aléon, Jérôme; Robert, François; Duprat, Jean; Derenne, Sylvie

2005-09-15

48

Extreme oxygen isotope ratios in the early Solar System  

NASA Astrophysics Data System (ADS)

The origins of the building blocks of the Solar System can be studied using the isotopic composition of early planetary and meteoritic material. Oxygen isotopes in planetary materials show variations at the per cent level that are not related to the mass of the isotopes; rather, they result from the mixture of components having different nucleosynthetic or chemical origins. Isotopic variations reaching orders of magnitude in minute meteoritic grains are usually attributed to stellar nucleosynthesis before the birth of the Solar System, whereby different grains were contributed by different stars. Here we report the discovery of abundant silica-rich grains embedded in meteoritic organic matter, having the most extreme 18O/16O and 17O/16O ratios observed (both ~10-1) together with a solar silicon isotopic composition. Both O and Si isotopes indicate a single nucleosynthetic process. These compositions can be accounted for by one of two processes: a single exotic evolved star seeding the young Solar System, or irradiation of the circumsolar gas by high energy particles accelerated during an active phase of the young Sun. We favour the latter interpretation, because the observed compositions are usually not expected from nucleosynthetic processes in evolved stars, whereas they are predicted by the selective trapping of irradiation products.

Aléon, Jérôme; Robert, François; Duprat, Jean; Derenne, Sylvie

2005-09-01

49

Emissivity measurements for YSZ thermal barrier coating at high temperatures using a 1.6-um single-wavelength pyrometer  

Microsoft Academic Search

A method that employs an integrating sphere and a single-wavelength (1.5-micrometers ) pyrometer to measure the spectral effective emissivities of YSZ thermal barrier coatings in the temperature range (approximately 650 to 1050 degree(s)C) is described. The effective spectral emissivities for two YSZ samples are measured as a function of the heat cycle duration. An increase in the emissivity of the

Sami D. Alaruri; Lisa Bianchini; Andrew Brewington

1998-01-01

50

Simulating extreme-mass-ratio systems in full general relativity  

NASA Astrophysics Data System (ADS)

We introduce a new method for numerically evolving the full Einstein field equations in situations where the spacetime is dominated by a known background solution. The technique leverages the knowledge of the background solution to subtract off its contribution to the truncation error, thereby more efficiently achieving a desired level of accuracy. We demonstrate the method by applying it to the radial infall of a solar-type star into supermassive black holes with mass ratios ?106. The self-gravity of the star is thus consistently modeled within the context of general relativity, and the star’s interaction with the black hole computed with moderate computational cost, despite the over five orders of magnitude difference in gravitational potential (as defined by the ratio of mass to radius). We compute the tidal deformation of the star during infall, and the gravitational wave emission, finding the latter is close to the prediction of the point-particle limit.

East, William E.; Pretorius, Frans

2013-05-01

51

Surface heat flux data from energy balance Bowen ratio systems  

SciTech Connect

The 350 {times} 400 km domain of the Atmospheric Radiation Measurement (ARM) Program`s Clouds and Radiation Testbed (CART) site in the southern Great Plains is equipped with 10 energy balance Bowen ratio (EBBR) stations at grassland sites; they measure the net radiation, ground heat flux, and temperature/humidity differences between 1.0 and 2.0 m heights. The latter differences provide estimates of the geometric Bowen ratio ({beta}), which are used to estimate sensible and latent heat fluxes. This paper addresses the problem that occurs when the value of {beta} is near {minus}1 and to demonstrate the effectiveness of the EBBR stations in collecting energy flux data at the CART site.

Wesely, M.L.; Cook, D.R.; Coulter, R.L.

1995-06-01

52

21 CFR 862.1455 - Lecithin/sphingomyelin ratio in amniotic fluid test system.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Lecithin/sphingomyelin ratio in amniotic fluid...Chemistry Test Systems § 862.1455 Lecithin/sphingomyelin ratio in amniotic fluid test system. (a) Identification. A lecithin/sphingomyelin ratio in amniotic...

2010-04-01

53

21 CFR 862.1455 - Lecithin/sphingomyelin ratio in amniotic fluid test system.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Lecithin/sphingomyelin ratio in amniotic fluid...Chemistry Test Systems § 862.1455 Lecithin/sphingomyelin ratio in amniotic fluid test system. (a) Identification. A lecithin/sphingomyelin ratio in amniotic...

2009-04-01

54

Control system and method for a power delivery system having a continuously variable ratio transmission  

DOEpatents

A control system and method for a power delivery system, such as in an automotive vehicle, having an engine coupled to a continuously variable ratio transmission (CVT). Totally independent control of engine and transmission enable the engine to precisely follow a desired operating characteristic, such as the ideal operating line for minimum fuel consumption. CVT ratio is controlled as a function of commanded power or torque and measured load, while engine fuel requirements (e.g., throttle position) are strictly a function of measured engine speed. Fuel requirements are therefore precisely adjusted in accordance with the ideal characteristic for any load placed on the engine. 4 figs.

Frank, A.A.

1984-07-10

55

Design of high ratio middle infrared continuous zoom optical system  

NASA Astrophysics Data System (ADS)

In recent years, the demand for infrared zoom systems is increasing in proportion with the development of infrared technology and its applications. To meet this demand a variety of zoom lenses have been designed. Infrared cameras operating in the 3-5?m spectral band are used in a wide variety of applications such as targeting, rescue, guidance and surveillance systems as well as other equipment. This paper using cool 320×240 detector with staring focal plane array and secondary imaging, a mid-wave optical system using mechanical-compensated with large-aperture and a zoom range of 10:1 is designed. The Pixel Dimensions of the detector is 30?m, and the wavelength between 3.7?m ~4.8?m.The system adopts negative group variable times and positive group of compensation which can realize 33mm~330mm continuous zoom and FOV =20.61°~2.08° ,it consists of 7 lenses including 3 aspheric surface. The length of the system is 262mm with the reflection mirror multipass optical path. The results show that the modulation transfer function(MTF)are above 0.4 within the whole focal range at spatial frequency of 17 lp/mm, and Root Mean Square (RMS) value of spot diameter were smaller than the Pixel Dimensions. After the image quality being optimized, the narcissus analysis is done and 100% cold shield efficiency is obtained. Finallythe monotonic and smooth Cam curve is given. The curve shows that the imaging plane is stable and the cam is easy to process. The system has advantages of simple structure, high image quality and short zoom path etc.

Fan, Zheyuan; Cao, Jianzhong; Yang, Hongtao; Qu, Enshi; Wu, Dengshan

2011-06-01

56

CENOSES AND THE GOLDEN RATIO IN ENGINEERING SYSTEMS  

Microsoft Academic Search

Scientific and technological progress has nowadays achieved such stage of development when diver- sity of the products being manufactured can be commensurable with species diversity in the nature. Evo- lution laws of technology comprising individual elements, and wildlife consisting of separate species have a lot in common. When engineering systems achieve certain complexity level they begin to obey the same

A. Yu. Yuzhannikov

57

Global qualitative analysis of a ratio-dependent predator–prey system  

Microsoft Academic Search

.  ?Ratio-dependent predator–prey models are favored by many animal ecologists recently as more suitable ones for predator–prey\\u000a interactions where predation involves searching process. However, such models are not well studied in the sense that most\\u000a results are local stability related. In this paper, we consider the global behaviors of solutions of a ratio-dependent predator–prey\\u000a systems. Specifically, we shall show that ratio

Yang Kuang; Edoardo Beretta

1998-01-01

58

Mechanically compensated type for midwave infrared zoom system with a large zoom ratio  

NASA Astrophysics Data System (ADS)

In some circumstances, there is a need for a midwave infrared (MWIR) zoom system with a large zoom ratio. Using traditional four-component mechanically compensated types of MWIR zoom systems cannot achieve a large zoom ratio. To meet this demand, we describe a six-component mechanically compensated type. The thin-lens theory of this type is developed and equations are presented. Using the six-component mechanically compensated type, a MWIR continuous zoom system with a zoom ratio of 45 is designed, and it has high image quality over the entire zoom range.

Hao, Zhou; Ying, Liu; Qiang, Sun; Chun, Li; Xiaolong, Zhang; Jianbo, Huang

2013-01-01

59

The effect of metallicity on the minimum mass ratio of W Ursae Majoris-type systems  

NASA Astrophysics Data System (ADS)

According to the prevenient theoretical study, the minimum mass ratio for tidal stability of W Ursae Majoris (W UMa) systems is q min =( M 2/ M 1)˜0.071-0.078. However, the mass ratios of some observed W UMa binaries are smaller than the theoretical minimum mass ratio. Using Eggleton’s stellar evolution code, we study the effects of metallicity and evolution on the minimum mass ratio of W UMa systems ( M 1=1.2 M ?). We assume that k12=k22 for the component’s dimensionless gyration radii and that the contact degree is about 70 per cent. We find that the dynamical stability of W UMa binaries depends on the metallicity of W UMa systems. For the W UMa systems at age = 0 Gyr, the distribution of the minimum mass ratio has a fairly wide range, from 0.083 to 0.064, with the metallicity range from Z=0.0001 to 0.03. W UMa systems with Z=0.01 have the smallest value of the minimum mass ratio, which is about 0.064. The existence of low- q systems can be explained partly by the dependence of the dimensionless gyration radius on the metallicity. In addition, the dependence of the minimum mass ratio on the evolution, as suggested by previously work, is confirmed.

Jiang, Dengkai; Han, Zhanwen; Liu, Cheng; Wang, Jiancheng; Li, Lifang

2010-10-01

60

Maximum mass flow ratio due to secondary flow choking in an ejector refrigeration system  

Microsoft Academic Search

The occurrence of flow choking in an ejector of an ejector refrigeration system (ERS) was analysed and a model for predicting the maximum flow ratio of the ejector was developed. The multi-parameter equation to calculate the mass flow ratio takes into account the performance of the primary nozzle, the flow entrainment and mixing relating to ejector geometry and operating conditions.

S. K. Chou; P. R. Yang; C. Yap

2001-01-01

61

21 CFR 862.1455 - Lecithin/sphingomyelin ratio in amniotic fluid test system.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Chemistry Test Systems § 862.1455 Lecithin/sphingomyelin ratio in amniotic fluid test...

2013-04-01

62

A trading-ratio system for trading water pollution discharge permits  

Microsoft Academic Search

The fact that water flows to the lowest level uni-directionally is a very specific and useful property of water. By utilizing this property, we design a trading-ratio system (TRS) of tradable discharge permits for water pollution control. Such a trading-ratio system has three main characteristics: (1) the zonal effluent cap is set by taking into account the water pollutant loads

Ming-Feng Hung; Daigee Shaw

2005-01-01

63

The Determination of Heat Capacity Ratios in a Simple Open System  

Microsoft Academic Search

A virtually closed system is treated as open and compared to known results. The classic experiment of Clement and Desormes provides the conceptual framework for this open system approach in determining the molar heat capacity ratios, lambda. This alternate view, extends the theoretical treatment beyond the first law of thermodynamics for closed systems, utilizing both an energy and entropy balance,

Glen L. Holden

2007-01-01

64

Generation Ratio Availability Assessment of Electrical Systems for Offshore Wind Farms  

Microsoft Academic Search

An availability index, Generation Ratio Availability (GRA), is proposed to evaluate the electrical system of offshore wind farms (OWF). The GRA is the probability that at least a certain percent of wind power could be transferred to the grid system through the concerned electrical system. The GRA does not depend on the load demand and has weaker correlation with the

Menghua Zhao; Zhe Chen; Frede Blaabjerg

2007-01-01

65

Experimental determination of the optimum performance of ejector refrigeration system depending on ejector area ratio  

Microsoft Academic Search

The performance of the ejector refrigeration system using ejectors with cylindrical mixing chamber is studied at operating conditions with choking in the mixing chamber. The condenser pressure is chosen so that the secondary flow choking can occur even in the ejector with the smallest area ratio. In the present study, the performance of the constructed system is determined by using

R. Yap?c?; H. K. Ersoy; A. Aktoprako?lu; H. S. Halkac?; O. Yi?it

2008-01-01

66

The Determination of Heat Capacity Ratios in a Simple Open System  

ERIC Educational Resources Information Center

|A virtually closed system is treated as open and compared to known results. The classic experiment of Clement and Desormes provides the conceptual framework for this open system approach in determining the molar heat capacity ratios, lambda. This alternate view, extends the theoretical treatment beyond the first law of thermodynamics for closed…

Holden, Glen L.

2007-01-01

67

Effect of sex ratio on the immune system of Oreochromis mossambicus (Peters)  

Microsoft Academic Search

The social environment of fish has a crucial role to play on the immune system and hence on the overall health status. Stressors of social origin such as dominance, subordination, and fight for mate have a major impact on the immune system of fish. The present study was designed with the objective of finding the effect of sex ratio of

C. Binuramesh; M. Prabakaran; Dieter Steinhagen; R. Dinakaran Michael

2006-01-01

68

The Determination of Heat Capacity Ratios in a Simple Open System  

ERIC Educational Resources Information Center

A virtually closed system is treated as open and compared to known results. The classic experiment of Clement and Desormes provides the conceptual framework for this open system approach in determining the molar heat capacity ratios, lambda. This alternate view, extends the theoretical treatment beyond the first law of thermodynamics for closed…

Holden, Glen L.

2007-01-01

69

Optimization of Height-to-Diameter Ratio for an Accelerator-Driven System  

Microsoft Academic Search

The height-to-diameter (H\\/D) ratio of a lead-bismuth eutectic (LBE)-cooled accelerator-driven system (ADS) has been evaluated in terms of the neutron multiplication, the coolant void worth, and the coolant velocity. For a model ADS, an optimization of the H\\/D ratio is performed with a Monte Carlo code both for the effective multiplication factor k{sub eff} and for the multiplication of the

Yonghee Kim; Won Seok Park; Tae Yung Song; Chang Kue Park

2003-01-01

70

Reducing the peak-to-average power ratio in OFDM radio transmission systems  

Microsoft Academic Search

An important difficulty which has to be solved in OFDM transmission systems is the large peak-to-average power ratio of the OFDM signal. Without any measures, the signal is limited by the power amplifier in the transmitter which causes interference both of the signal itself and in adjacent frequency bands. A method is proposed which considerably reduces the peak-to-average power ratio

Thomas May; Hermann Rohling

1998-01-01

71

Ratio-Lindahl equilibria and an informationally efficient and implementable mixed-ownership system  

Microsoft Academic Search

In this paper, we formalize an informationally efficient and implementable mixed-ownership economic institutional framework by using the Ratio-Lindahl equilibrium that yields Pareto-efficient and individually rational allocations for public goods economies with general variable returns. We consider the incentive aspects of the system by giving an “incentive-compatible,” informationally efficient, and “privacy preserving” mechanism whose Nash allocations coincide with Ratio-Lindahl allocations. Moreover,

Guoqiang Tian; Qi Li

1995-01-01

72

The analysis of signal-to-noise ratio of airborne LIDAR system under state of motion  

NASA Astrophysics Data System (ADS)

This article gives an overview of airborne LIDAR (laser light detection and ranging) system and its application. By analyzing the transmission and reception process of laser signal, the article constructs a model of echo signal of the LIDAR system, and gives some basic formulas which make up the relationship of signal-to-noise ratio, for example, the received power, the dark noise power and so on. And this article carefully studies and analyzes the impact of some important parameters in the equation on the signal-to-noise ratio, such as the atmospheric transmittance coefficient, the work distance. And the matlab software is used to simulate the detection environment, and obtains a series values of signal-to-noise (SNR) ratio under different circumstances such as sunny day, cloudy day, day, night. And the figures which describe how the SNR of LIDAR system is influenced by the critical factors are shown in the article. Finally according to the series values of signal-to-noise ratio and the figures, the SNR of LIDAR system decreases as the distance increases, and the atmospheric transmittance coefficient caused by bad weather, and also high work temperature drops the SNR. Depending on these conclusions, the LIDAR system will work even better.

Hao, Huang; Lan, Tian; Zhang, Yingchao; Ni, Guoqiang

2010-11-01

73

An experimental system for spectral line ratio measurements in the TJ-II stellarator  

SciTech Connect

The chord-integrated emissions of spectral lines have been monitored in the TJ-II stellarator by using a spectral system with time and space scanning capabilities and relative calibration over the entire UV-visible spectral range. This system has been used to study the line ratio of lines of different ionization stages of carbon (C{sup 5+} 5290 A and C{sup 4+} 2271 A) for plasma diagnostic purposes. The local emissivity of these ions has been reconstructed, for quasistationary profiles, by means of the inversion Fisher method described previously. The experimental line ratio is being empirically studied and in parallel a simple spectroscopic model has been developed to account for that ratio. We are investigating whether the role played by charge exchange processes with neutrals and the existence of non-Maxwellian electrons, intrinsic to Electron Cyclotron Resonance Heating (ECRH) heating, leave any distinguishable mark on this diagnostic method.

Zurro, B.; Baciero, A.; Fontdecaba, J. M.; Jimenez-Rey, D. [Laboratorio Nacional de Fusion por Confinamiento Magnetico, Asociacion EURATOM-CIEMAT, E-28040 Madrid (Spain); Pelaez, R. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, E-4701 Valladolid (Spain)

2008-10-15

74

Improvement of signal-to-interference ratio and signal-to-noise ratio in nerve cuff electrode systems.  

PubMed

Cuff electrodes are effective for chronic electroneurogram (ENG) recording while minimizing nerve damage. However, the ENG signals are usually contaminated by electromyogram (EMG) activity from the surrounding muscles, stimulus artifacts produced by the electrical stimulation and noise generated in the first stage of the neural signal amplifier. This paper proposed a new cuff electrode to reduce the interference from EMG signals and stimulus artifacts. As a result, when an additional middle electrode was placed at the center of the cuff electrode, a significant improvement in the signal-to-interference ratio was achieved at 11% for the EMG signals and 12% for the stimulus artifacts when compared to a conventional tripolar cuff. Furthermore, a new low-noise amplifier was proposed to improve the signal-to-noise ratio. The circuit was designed based on a noise analysis to minimize the noise, and the results show that the total noise of the amplifier was below 1??V for a cuff impedance of 1 k? and a frequency bandwidth of 300 to 5000 Hz. PMID:22551721

Chu, Jun-Uk; Song, Kang-Il; Han, Sungmin; Lee, Soo Hyun; Kim, Jinseok; Kang, Ji Yoon; Hwang, Dosik; Suh, Jun-Kyo Francis; Choi, Kuiwon; Youn, Inchan

2012-05-03

75

Disk-Planets Interactions and the Diversity of Period Ratios in Kepler's Multi-planetary Systems  

NASA Astrophysics Data System (ADS)

The Kepler mission is dramatically increasing the number of planets known in multi-planetary systems. Many adjacent planets have orbital period ratios near resonant values, with a tendency to be larger than required for exact first-order mean-motion resonances. This feature has been shown to be a natural outcome of orbital circularization of resonant planetary pairs due to star-planet tidal interactions. However, this feature holds in multi-planetary systems with periods longer than 10 days, in which tidal circularization is unlikely to provide efficient divergent evolution of the planets' orbits to explain these orbital period ratios. Gravitational interactions between planets and their parent protoplanetary disk may instead provide efficient divergent evolution. For a planet pair embedded in a disk, we show that interactions between a planet and the wake of its companion can reverse convergent migration and significantly increase the period ratio from a near-resonant value. Divergent evolution due to wake-planet interactions is particularly efficient when at least one of the planets opens a partial gap around its orbit. This mechanism could help account for the diversity of period ratios in Kepler's multiple systems from super-Earth to sub-Jovian planets with periods greater than about 10 days. Diversity is also expected for pairs of planets massive enough to merge their gap. The efficiency of wake-planet interactions is then much reduced, but convergent migration may stall with a variety of period ratios depending on the density structure in the common gap. This is illustrated for the Kepler-46 system, for which we reproduce the period ratio of Kepler-46b and c.

Baruteau, Clement; Papaloizou, John C. B.

2013-11-01

76

Addition of Gaussian random signals for peak to average power ratio reduction in OFDM systems  

Microsoft Academic Search

This paper investigates the problem of peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) system. It presents a new PAPR reduction method based on addition of power of random signals in a complex Gaussian distribution form to the data constellation points in frequency domain. The added signals alter the constellation shape by shifting the constellation points from their

Wisam F. Al-Azzo; Borhanuddin M. Ali; Sabira Khatun; Syed M. Bilfagih; Nor K. Noordin

2008-01-01

77

Efficient high-order methods based on golden ratio for nonlinear systems  

Microsoft Academic Search

We derive new iterative methods with order of convergence four or higher, for solving nonlinear systems, by composing iteratively golden ratio methods with a modified Newton’s method. We use different efficiency indices in order to compare the new methods with other ones and present several numerical tests which confirm the theoretical results.

Alicia Cordero; José L. Hueso; Eulalia Martínez; Juan R. Torregrosa

2011-01-01

78

Carbon\\/nitrogen ratio as a control element in aquaculture systems  

Microsoft Academic Search

Controlling the inorganic nitrogen by manipulating the carbon\\/nitrogen ratios is a potential control method for aquaculture systems. This approach seems to be a practical and inexpensive means of reducing the accumulation of inorganic nitrogen in the pond. Nitrogen control is induced by feeding bacteria with carbohydrates, and through the subsequent uptake of nitrogen from the water, by the synthesis of

Yoram Avnimelech

1999-01-01

79

Bionomic Exploitation of a Ratio-Dependent Predator-Prey System  

ERIC Educational Resources Information Center

|The present article deals with the problem of combined harvesting of a Michaelis-Menten-type ratio-dependent predator-prey system. The problem of determining the optimal harvest policy is solved by invoking Pontryagin's Maximum Principle. Dynamic optimization of the harvest policy is studied by taking the combined harvest effort as a dynamic…

Maiti, Alakes; Patra, Bibek; Samanta, G. P.

2008-01-01

80

Air-Flow Redistribution in Exhaust Ventilation Systems Using Dampers and Static Pressure Ratios  

Microsoft Academic Search

Ventilation manuals often heavily discourage use of dampers even though dampers offer the much-needed ability to change air-flow distribution to meet changing needs. If dampers can be adjusted accurately, quickly, and easily, there may be reason to discourage their use only for systems that transport particulates. A method is described for adjustment of ventilation flow dampers using only the ratio

Steven E. Guffey

1993-01-01

81

Progogine-Defay Ratio for Systems with More Than One Order Parameter.  

National Technical Information Service (NTIS)

The Progogine-Defay ratio, Pi delta Cp Delta Kappa/TV(delta alpha) squared, has been derived for systems whose states need to be specified in terms of a number of order parameters by considering the conditions of tangency of the equilibrium free energy su...

P. K. Gupta C. T. Moynihan

1975-01-01

82

Aspect-ratio dependence of percolation probability in a rectangular system  

NASA Astrophysics Data System (ADS)

I investigate site percolation on a rectangular system (aspect ratio a) of a square lattice for a given occupation probability p (not restricted to pc) using computer simulations. The dependence of the percolation probability R on a is shown and analyzed on the basis of a modified finite-size scaling function. A method for evaluating R without statistical simulations is proposed for given conditions (longitudinal dimension L, a, and p) of the system.

Tsubakihara, Shinsuke

2000-12-01

83

Universal upper bound on the entropy-to-energy ratio for bounded systems  

Microsoft Academic Search

We present evidence for the existence of a universal upper bound of magnitude 2..pi..R\\/hc to the entropy-to-energy ratio S\\/E of an arbitrary system of effective radius R. For systems with negligible self-gravity, the bound follows from application of the second law of thermodynamics to a gedanken experiment involving a black hole. Direct statistical arguments are also discussed. A microcanonical approach

Jacob Bekenstein

1981-01-01

84

Inhibition to excitation ratio regulates visual system responses and behavior in vivo  

PubMed Central

The balance of inhibitory to excitatory (I/E) synaptic inputs is thought to control information processing and behavioral output of the central nervous system. We sought to test the effects of the decreased or increased I/E ratio on visual circuit function and visually guided behavior in Xenopus tadpoles. We selectively decreased inhibitory synaptic transmission in optic tectal neurons by knocking down the ?2 subunit of the GABAA receptors (GABAAR) using antisense morpholino oligonucleotides or by expressing a peptide corresponding to an intracellular loop of the ?2 subunit, called ICL, which interferes with anchoring GABAAR at synapses. Recordings of miniature inhibitory postsynaptic currents (mIPSCs) and miniature excitatory PSCs (mEPSCs) showed that these treatments decreased the frequency of mIPSCs compared with control tectal neurons without affecting mEPSC frequency, resulting in an ?50% decrease in the ratio of I/E synaptic input. ICL expression and ?2-subunit knockdown also decreased the ratio of optic nerve-evoked synaptic I/E responses. We recorded visually evoked responses from optic tectal neurons, in which the synaptic I/E ratio was decreased. Decreasing the synaptic I/E ratio in tectal neurons increased the variance of first spike latency in response to full-field visual stimulation, increased recurrent activity in the tectal circuit, enlarged spatial receptive fields, and lengthened the temporal integration window. We used the benzodiazepine, diazepam (DZ), to increase inhibitory synaptic activity. DZ increased optic nerve-evoked inhibitory transmission but did not affect evoked excitatory currents, resulting in an increase in the I/E ratio of ?30%. Increasing the I/E ratio with DZ decreased the variance of first spike latency, decreased spatial receptive field size, and lengthened temporal receptive fields. Sequential recordings of spikes and excitatory and inhibitory synaptic inputs to the same visual stimuli demonstrated that decreasing or increasing the I/E ratio disrupted input/output relations. We assessed the effect of an altered I/E ratio on a visually guided behavior that requires the optic tectum. Increasing and decreasing I/E in tectal neurons blocked the tectally mediated visual avoidance behavior. Because ICL expression, ?2-subunit knockdown, and DZ did not directly affect excitatory synaptic transmission, we interpret the results of our study as evidence that partially decreasing or increasing the ratio of I/E disrupts several measures of visual system information processing and visually guided behavior in an intact vertebrate.

Shen, Wanhua; McKeown, Caroline R.; Demas, James A.

2011-01-01

85

On the modal damping ratios of shear-type structures equipped with Rayleigh damping systems  

NASA Astrophysics Data System (ADS)

The effects of added manufactured viscous dampers upon shear-type structures are analytically investigated here for the class of Rayleigh damping systems. The definitions of mass proportional damping (MPD) and stiffness proportional damping (SPD) systems are briefly recalled and their physical counterpart is derived. From basic physics, a detailed mathematical demonstration that the first modal damping ratio of a structure equipped with the MPD system is always larger than the first modal damping ratio of a structure equipped with the SPD system is provided here. All results are derived for the class of structures characterised by constant values of lateral stiffness and storey mass, under the equal “total size” constraint. The paper also provides closed form demonstrations of other properties of modal damping ratios which further indicate that the MPD and the SPD systems are respectively characterised by the largest and the smallest damping efficiency among Rayleigh damping systems subjected to base excitation. A numerical application with realistic data corresponding to an actual seven-storey building structure is presented to illustrate and verify the theoretical findings.

Trombetti, T.; Silvestri, S.

2006-04-01

86

Optimization of Height-to-Diameter Ratio for an Accelerator-Driven System  

SciTech Connect

The height-to-diameter (H/D) ratio of a lead-bismuth eutectic (LBE)-cooled accelerator-driven system (ADS) has been evaluated in terms of the neutron multiplication, the coolant void worth, and the coolant velocity. For a model ADS, an optimization of the H/D ratio is performed with a Monte Carlo code both for the effective multiplication factor k{sub eff} and for the multiplication of the external neutrons. In the optimization, ten cases of H/D values have been analyzed for a homogeneous fuel blanket. Also, the dependency of the optimal H/D ratio on the target/buffer is addressed. The Monte Carlo simulations show that the optimal H/D configuration of the ADS core is quite different for the two important measures, and a high H/D ratio can provide a significantly higher source multiplication than the traditional pancake core. Furthermore, various core analyses including depletion calculations are conducted for three selected heterogeneous cores with different H/D ratios, which are a small H/D value (pancake type), a medium H/D value, and a high H/D value, respectively. Void reactivity coefficients of the LBE coolant are evaluated and compared for the three designs to quantify the effects of the H/D ratio. Additionally, a thermal-hydraulic analysis has been performed to derive a maximum allowable core height subject to the LBE velocity limit due to its corrosion and erosion characteristics. It is shown that the practically optimal H/D ratio for source multiplication is tightly constrained by the maximum allowable LBE velocity, depending on the core design parameters.

Kim, Yonghee; Park, Won Seok; Song, Tae Yung; Park, Chang Kue [Korea Atomic Energy Research Institute (Korea, Republic of)

2003-02-15

87

Ratio-dependent response of a temperate Australian estuarine system to sustained nitrogen loading.  

PubMed

Classical resource- and the less studied ratio-dependent models of predator-prey relationships provide divergent predictions as to the sustained ecological effects of bottom-up forcing. While resource-dependent models, which consider only instantaneous prey density in modelling predator responses, predict community responses that are dependent on the number of trophic levels in a system, ratio-dependent models, which consider the number of prey per consumer, predict proportional increase in each level irrespective of chain length. The two models are only subtly different for systems with two or three trophic levels but in the case of four trophic levels, predict opposite effects of enrichment on primary producers. Despite the poor discriminatory power of tests of the models in systems with two or three trophic levels, field tests in estuarine and marine systems with four trophic levels have been notably absent. Sampling of phytoplankton, macroinvertebrates, invertebrate-feeding fishes, piscivorous fishes in Kooloonbung Creek, Hastings River estuary, eastern Australia, subject to over 20 years of sewage discharge, revealed increased abundances in all four trophic levels at the disturbed location relative to control sites. Increased abundance of phytoplankton at the disturbed site was counter to the predictions of resource-dependent models, which posit a reduction in the first trophic level in response to enrichment. By contrast, the increase in abundance of this first trophic level and the proportionality of increases in abundances of each of the four trophic groups to nitrogen loading provided strong support for ratio dependency. This first evidence of ratio dependence in an estuarine system with four trophic levels not only demonstrates the applicability of ecological theory which seeks to simplify the complexity of systems, but has implications for management. Although large nutrient inputs frequently induce mortality of invertebrates and fish, we have shown that smaller inputs may in fact enhance biomass of all trophic levels. PMID:16845540

Bishop, Melanie J; Kelaher, Brendan P; Smith, Marcus P Lincoln; York, Paul H; Booth, David J

2006-07-15

88

Low molecular weight chitosan nanoparticulate system at low N:P ratio for nontoxic polynucleotide delivery.  

PubMed

Chitosan, a natural polymer, is a promising system for the therapeutic delivery of both plasmid DNA and synthetic small interfering RNA. Reports attempting to identify the optimal parameters of chitosan for synthetic small interfering RNA delivery were inconclusive with high molecular weight at high amine-to-phosphate (N:P) ratios apparently required for efficient transfection. Here we show, for the first time, that low molecular weight chitosan (LMW-CS) formulations at low N:P ratios are suitable for the in vitro delivery of small interfering RNA. LMW-CS nanoparticles at low N:P ratios were positively charged (?-potential ~20 mV) with an average size below 100 nm as demonstrated by dynamic light scattering and environmental scanning electron microscopy, respectively. Nanoparticles were spherical, a shape promoting decreased cytotoxicity and enhanced cellular uptake. Nanoparticle stability was effective for at least 20 hours at N:P ratios above two in a slightly acidic pH of 6.5. At a higher basic pH of 8, these nanoparticles were unravelled due to chitosan neutralization, exposing their polynucleotide cargo. Cellular uptake ranged from 50% to 95% in six different cell lines as measured by cytometry. Increasing chitosan molecular weight improved nanoparticle stability as well as the ability of nanoparticles to protect the oligonucleotide cargo from nucleases at supraphysiological concentrations. The highest knockdown efficiency was obtained with the specific formulation 92-10-5 that combines sufficient nuclease protection with effective intracellular release. This system attained >70% knockdown of the messenger RNA, similar to commercially available lipoplexes, without apparent cytotoxicity. Contrary to previous reports, our data demonstrate that LMW-CS at low N:P ratios are efficient and nontoxic polynucleotide delivery systems capable of transfecting a plethora of cell lines. PMID:22457597

Alameh, Mohamad; Dejesus, Diogo; Jean, Myriam; Darras, Vincent; Thibault, Marc; Lavertu, Marc; Buschmann, Michael D; Merzouki, Abderrazzak

2012-03-13

89

Low molecular weight chitosan nanoparticulate system at low N:P ratio for nontoxic polynucleotide delivery  

PubMed Central

Chitosan, a natural polymer, is a promising system for the therapeutic delivery of both plasmid DNA and synthetic small interfering RNA. Reports attempting to identify the optimal parameters of chitosan for synthetic small interfering RNA delivery were inconclusive with high molecular weight at high amine-to-phosphate (N:P) ratios apparently required for efficient transfection. Here we show, for the first time, that low molecular weight chitosan (LMW-CS) formulations at low N:P ratios are suitable for the in vitro delivery of small interfering RNA. LMW-CS nanoparticles at low N:P ratios were positively charged (?-potential ~20 mV) with an average size below 100 nm as demonstrated by dynamic light scattering and environmental scanning electron microscopy, respectively. Nanoparticles were spherical, a shape promoting decreased cytotoxicity and enhanced cellular uptake. Nanoparticle stability was effective for at least 20 hours at N:P ratios above two in a slightly acidic pH of 6.5. At a higher basic pH of 8, these nanoparticles were unravelled due to chitosan neutralization, exposing their polynucleotide cargo. Cellular uptake ranged from 50% to 95% in six different cell lines as measured by cytometry. Increasing chitosan molecular weight improved nanoparticle stability as well as the ability of nanoparticles to protect the oligonucleotide cargo from nucleases at supraphysiological concentrations. The highest knockdown efficiency was obtained with the specific formulation 92-10-5 that combines sufficient nuclease protection with effective intracellular release. This system attained >70% knockdown of the messenger RNA, similar to commercially available lipoplexes, without apparent cytotoxicity. Contrary to previous reports, our data demonstrate that LMW-CS at low N:P ratios are efficient and nontoxic polynucleotide delivery systems capable of transfecting a plethora of cell lines.

Alameh, Mohamad; DeJesus, Diogo; Jean, Myriam; Darras, Vincent; Thibault, Marc; Lavertu, Marc; Buschmann, Michael D; Merzouki, Abderrazzak

2012-01-01

90

Effects of dietary n-6:n-3 ratio on immune and reproductive systems of pullet chicks.  

PubMed

The objective of this study was to examine the effects of dietary n-6:n-3 ratio on immune and reproduction systems of Leghorn pullet chicks. A total of 216 Hy-Line W-36 pullet chicks (1 d old) were randomly assigned to 3 diets (n-6:n-3 ratios of 10, 6, and 2) until 22 wk of age. The Optomega-50 (Optivite International Ltd., Nottinghamshire, UK) containing 50% salmon fish oil was used as an n-3 source. Pullets were injected with SRBC suspension at 6 and 9 wk and anti-SRBC titers were measured 7 and 14 d after each immunization. The antibody (Ab) titers for Newcastle disease (ND), avian influenza, infectious bronchitis (IB), and infectious bursal disease (IBD) were determined at 4, 6, 10, 14, and 18 wk of age. Pullets fed diet with the n-6:n-3 ratio of 2 had higher feed consumption and lower BW gain (P < 0.05) compared those fed diets with the ratios of 6 and 10. The results demonstrated that the different dietary n-6:n-3 ratios did not have a significant effect on the anti-SRBC titers in pullets serum (P > 0.05). The Ab production against avian influenza vaccine was increased in pullets fed diet containing the n-6:n-3 ratio of 10 at wk 10 and 14 and increased for ND at only 14 wk (P < 0.05). On the other hand, the Ab response to IBD (14 wk) and IB (14 wk) vaccines was increased when pullets were fed diet containing a ratio of 6 (P < 0.05). The pullets fed diet with the n-6:n-3 ratio of 2 showed lower egg production and late sexual maturity (P > 0.05) whereas ovary weight (P = 0.01) and number of large yellow follicles (P = 0.049) were significantly decreased at first oviposition. Our results revealed that the supplementation of Optomega-50 as a source of n-3 to decrease the n-6:n-3 ratio in diet significantly increased Ab production for ND, IB, and IBD in pullet chicks with slight reduction in reproductive organs weight at early production. PMID:21753213

Pilevar, M; Arshami, J; Golian, A; Basami, M R

2011-08-01

91

Photometric Studies of Twelve Deep, Low-mass Ratio Overcontact Binary Systems  

NASA Astrophysics Data System (ADS)

The formations of the blue straggler stars and the FK Com-type stars are unsolved problems in stellar astrophysics. One of the possibilities for their formations is from the coalescence of W UMa-type overcontact binary systems. Therefore, deep (f > 50%), low-mass ratio (q < 0.25) overcontact binary stars are a very important source to understand the phenomena of Blue Straggler/FK Com-type stars. Recently, 12 W UMa-type binary stars, FG Hya, GR Vir, IK Per, TV Mus, CU Tau, V857 Her, V410 Aur, XY Boo, SX CrV, QX And, GSC 619-232, and AH Cnc, were investigated photometrically. Apart from TV Mus, XY boo, and GSC 619-232, new observations of the other 9 binaries were obtained. Complete light curves of the 10 systems, FG Hya, GR Vir, IK Per, TV Mus, CU Tau, V857 Her, GSC 619-232, V410 Aur, XY Boo, and AH Cnc, were analyzed with the 2003 version of the W-D code. It is shown that all of those systems are deep (f > 50%), low-mass ratio (q < 0.25) overcontact binary stars. We found that the system GSC 619-232 has the highest degree of overcontact (f = 93.4%). The derived photometric mass ratio of V857 Her, q = 0.0653, indicates that it is the lowest-mass ratio system among W UMa-type binaries. Of the 12 sample stars, long-term period changes of 11 systems were found. About 58% (seven) of the sample binaries show cyclic period oscillation. No cyclic period changes were discovered for the other 5 systems, which may be caused by the short observational time interval or by insufficient observations. Therefore, we think that all W UMa-type binary stars may contain cyclic period variations. By considering the long-term period changes (both increase and decrease) of those binary stars, we proposed two evolutionary scenarios evolving from deep, low-mass ratio overcontact binaries into Blue Straggler/FK Com-type stars.

Qian, Shengbang; Yang, Yuangui; Zhu, Liying; He, Jiajia; Yuan, Jingzhao

2006-08-01

92

The influence of external source intensity in accelerator\\/target\\/blanket system on conversion ratio and fuel cycle  

Microsoft Academic Search

The analysis of neutron balance relation for a subcritical system with external source shows that a high ratio of neutron utilization (conversion ratio, breeding ratio) much exceeding similar values for nuclear reactors (both thermal or fast spectrum) is reachable in accelerator\\/target\\/blanket system with high external neutron source intensity. An accelerator\\/target\\/blanket systems with thermal power in blanket about 1850 Mwt and

Boris P. Kochurov; Boris P

1995-01-01

93

Branching ratio measurement of a ? system in Tm3+:YAG under a magnetic field  

NASA Astrophysics Data System (ADS)

A three-level ? system in Tm3+ doped YAG crystal is experimentally investigated in the prospect of quantum information processing. Zeeman effect is used to lift the nuclear spin degeneracy of this ion. In a previous paper [de Seze , Phys. Rev. B 73, 085112 (2006)] we measured the gyromagnetic tensor components and concluded that adequate magnetic field orientation could optimize the optical connection of both ground state sublevels to each one of the excited state sublevels, thus generating ? systems. Here we report on the direct measurement of the transition probability ratio along the two legs of the ? . Measurement techniques combine frequency selective optical pumping with optical nutation or photon echo processes.

Louchet, A.; Habib, J. S.; Crozatier, V.; Lorgeré, I.; Goldfarb, F.; Bretenaker, F.; Gouët, J.-L. Le; Guillot-Noël, O.; Goldner, Ph.

2007-01-01

94

Design of light condenser optical system based on membrane mirror with high power condenser ratio  

NASA Astrophysics Data System (ADS)

Light Condenser Optical system based on membrane mirror with high power condenser ratio is designed. This paper analyzed the impact of rope net structure prestress distribution on surface figure accuracy and its impact on the focal plane illuminance. Because GaAs cell performance will be affected by temperature, this paper also calculated the surface temperature of the gallium arsenide cells and analyzed its impact on the conversion efficiency. Appropriate method is proposed to resolve the problem. This research on photovoltaic generation has certain reference value particularly for space solar power system.

Liu, Chunyu; Jin, Guang

2012-10-01

95

Variable FOV optical illumination system with constant aspect ratio for 2-D array lasers diodes  

NASA Astrophysics Data System (ADS)

In this contribution we present a compact system to create an illumination distribution with a constant aspect ratio 3:4 and FOV from 0.4 to 1 degree. Besides, the system must delivery 40 W from 170 individual laser diodes placed in a regular 2-D array distribution of 10 x 20 mm. The main problem that must be solved is the high asymmetry of the individual sources; emission divergence's ratio 3:73 (0.3 vs. 7.4 degree) combined with the flux holes due to the laser's heat drain. In one axis (divergence of 0.3º) the best design strategy approach is a Galileo telescope but in the other axis a collimator configuration is the best solution. To manage both solutions at the same time is the aim of this contribution. Unfortunately for the Galileo strategy, source dimensions are too large so aspheric surfaces are needed, and the collimator configuration requires an EFL that must change from 573 to 1432 mm. The presented solution uses a set of three fixed anamorphic lenses, two of them pure cylinders, combined with a wheel of anamorphic lenses that have the function to change the FOV of the system. The most important contribution of the design is to obtain a constant final ratio 3:4 from an initial ratio of 3:73 with no losses of energy. The proposed solution produces an illumination pattern with peaks and valleys lower than 40%. This pattern distribution might be unacceptable for a standard illumination solution. However, the actual FOV is used to illuminate far away targets thus air turbulence is enough to homogenize the distribution on the target.

Arasa, J.; de la Fuente, M. C.; Ibañez, C.

2008-09-01

96

The minimum mass ratio of W UMa-type binary systems  

NASA Astrophysics Data System (ADS)

When the total angular momentum of a binary system Jtot = Jorb + Jspin is at a certain critical (minimum) value, a tidal instability occurs which eventually forces the stars to merge into a single, rapidly rotating object. The instability occurs when Jorb = 3Jspin, which in the case of contact binaries corresponds to a minimum mass ratio qmin ~ 0.071-0.078. The minimum mass ratio is obtained under the assumption that stellar radii are fixed and independent. This is not the case with contact binaries where, according to the Roche model, we have R2 = R2(R1, a, q). By finding a new criterion for contact binaries, which arises from dJtot = 0, and assuming k21 ? k22 for the component's dimensionless gyration radii, a theoretical lower limit qmin = 0.094-0.109 for overcontact degree f = 0-1 is obtained.

Arbutina, B.

2007-06-01

97

A new gas inlet system for an isotope ratio mass spectrometer improves reproducibility  

PubMed

We have developed a new inlet system for a gas sample isotope ratio mass spectrometer (IRMS). It is based on the well-known open split design from the gas chromatography/mass spectrometry (GC/MS) system due to its simplicity. The advantages over the conventional double inlet system with the metal bellows design include an improved reproducibility mainly due to a highly controllable pressure and temperature adjustment, a markedly lowered memory effect due to an uninterrupted gas flow through the ion source which limits adsorption/desorption processes on surfaces, and a single inlet capillary circumventing problems of asymmetrical behavior of sample and reference inlet paths. Furthermore, sample consumption is of the same order as for conventional measurements (i.e. about 0.4 mmol per hour), of which however only 2 &mgr;mol/h is used for the actual isotope ratio determination since the major gas amount acts as a gas flow seal against the atmosphere, corresponding to a 100-200 fold overkill. This may be improved in future systems. Copyright 2000 John Wiley & Sons, Ltd. PMID:10931551

Leuenberger; Nyfeler; Moret; Sturm; Huber

2000-01-01

98

Magnetization reversal with variation of the ratio of the anisotropy energies in exchange bias systems  

SciTech Connect

We systematically vary the ratio of the exchange and ferromagnetic anisotropies in a single multilayered system in finally unravelling the mysteries of magnetization reversal of exchange coupled systems. This is particularly possible due to increasing unidirectional exchange anisotropies in our multilayer system which we saw earlier from sequential switching of exchange coupled layers along the stack with increasing applied field strengths. Here, by introducing different directions ({theta}) of the applied field with respect to the unidirectional anisotropy direction, we have varied two different energy parameters: (i) the exchange anisotropy for each layer (ii) the ferromagnetic anisotropy. Our polarized neutron measurements thus show a gradual crossover from layer flipping (domain-wall motion) for low torque regimes of the effective field to coherent rotation for high torque regimes. We explain these findings within a general and simple model where the angular dependencies for reversal are guided by the relative strengths of Zeeman, exchange, and anisotropy energies.

Paul, Amitesh; Kentzinger, Emmanuel; Ruecker, Ulrich; Brueckel, Thomas [Institut fuer Festkoerperforschung, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)

2006-08-01

99

Calculation of signal-to-noise ratio (SNR) of infrared detection system based on MODTRAN model  

NASA Astrophysics Data System (ADS)

Signal-to-noise ratio (SNR) is an important parameter of infrared detection system. SNR of infrared detection system is determined by the target infrared radiation, atmospheric transmittance, background infrared radiation and the detector noise. The infrared radiation flux in the atmosphere is determined by the selective absorption of the gas molecules, the atmospheric environment, and the transmission distance of the radiation, etc, so the atmospheric transmittance and infrared radiance flux are intricate parameters. A radiometric model for the calculation of SNR of infrared detection system is developed and used to evaluate the effects of various parameters on signal-to-noise ratio (SNR). An atmospheric modeling tool, MODTRAN, is used to model wavelength-dependent atmospheric transmission and sky background radiance. Then a new expression of SNR is deduced. Instead of using constants such as average atmospheric transmission and average wavelength in traditional method, it uses discrete values for atmospheric transmission and sky background radiance. The integrals in general expression of SNR are converted to summations. The accuracy of SNR obtained from the new method can be improved. By adopting atmospheric condition of the 1976 US standard, no clouds urban aerosols, fall-winter aerosol profiles, the typical spectrum characters of sky background radiance and transmittance are computed by MODTRON. Then the operating ranges corresponding to the threshold quantity of SNR are calculated with the new method. The calculated operating ranges are more close to the measured operating range than those calculated with the traditional method.

Lu, Xue; Li, Chuang; Fan, Xuewu

2013-09-01

100

Urine ratio of tetrahydrocortisol to tetrahydrodeoxycortisol to screen for the systemic administration of cortisone and hydrocortisone.  

PubMed

We use gas chromatography-mass spectrometry (GC-MS) to determine the urine peak area ratio of tetrahydrocortisol (THF) to tetrahydrodeoxycortisol (THS) in spot urine samples of eight male volunteers after a single intramuscular injection of 100 mg hydrocortisone (HC) and after a single oral administration of 10 mg HC at six different post-treatment times over 24 h with 1 week between the two treatments. Control spot urine samples were also obtained from a group of 100 volunteers of each sex for GC-MS analysis. In addition, one female volunteer was collected for GC-MS and isotope ratio mass spectrometry (IRMS) analysis after a single oral administration of 40 mg HC and 40 mg cortisone (C) at 15 and 10 different post-treatment times over 30 h, respectively. IRMS analysis focused on the acetylated derivative of 11-keto-etiocholanolone (11KE) and 11beta-hydroxy-etiocholanolone (11OHE) as target metabolites, and on androsterone (A) as an endogenous reference compound (ERC) for calculating the corresponding delta(13)C (per thousand) depletion values. There was a small but significant sex-related difference for the THF/THS ratio in the control group with mean THF/THS ratio values of 10 and 13.5 for women and men, respectively. A cut-off value of 28 (mean+2 S.D.) for the THF/THS ratio offered a narrow detection window with 39% of suspicious samples after HC-oral treatment, and a wide detection window with 94% of suspicious samples after HC-intramuscular administration in men. For the woman the same cut-off value offered a wide detection window after HC and C administration with 100% and 90% of suspicious samples, respectively. On the basis of a cut-off value of 3 per thousand for the delta(13)C (per thousand) depletion, the exogenous origin was widely evidenced for at least one target compound in 93% and 80% of the HC and C samples, respectively. We conclude by discussing the predictive ability of the urine THF/THS ratio and its usefulness in pointing out suspicious samples resulting from the systemic administration of HC and C. PMID:19185436

Meklat, Noura; Tabet, Jean-Claude; de Ceaurriz, Jacques

2009-01-29

101

Radiation detection method and system using the sequential probability ratio test  

DOEpatents

A method and system using the Sequential Probability Ratio Test to enhance the detection of an elevated level of radiation, by determining whether a set of observations are consistent with a specified model within a given bounds of statistical significance. In particular, the SPRT is used in the present invention to maximize the range of detection, by providing processing mechanisms for estimating the dynamic background radiation, adjusting the models to reflect the amount of background knowledge at the current point in time, analyzing the current sample using the models to determine statistical significance, and determining when the sample has returned to the expected background conditions.

Nelson, Karl E. (Livermore, CA); Valentine, John D. (Redwood City, CA); Beauchamp, Brock R. (San Ramon, CA)

2007-07-17

102

Heavy Ion Fusion Science Virtual National Laboratory 2nd Quarter 2010 Milestone Report Develop the Theory Connecting Pyrometer and Streak Camera Spectrometer Data to the Material Properties of Beam Heated Targets and Compare to the Data.  

National Technical Information Service (NTIS)

This milestone has been accomplished. We have extended the theory that connects pyrometer and streak spectrometer data to material temperature on several fronts and have compared theory to NDCX-I experiments. For the case of NDCX-I, the data suggests that...

E. Henestroza F. M. Bieniosek J. J. Barnard P. A. Ni R. M. More S. Lidia

2010-01-01

103

Droplet charge-to-mass ratio measurement in an EHD liquid-liquid extraction system  

SciTech Connect

The application of a high voltage electric field to enhance the rate of mass transfer in liquid-liquid extraction has been an active subject of investigation in recent years. The electrohydrodynamic (EHD) forces generated by electric fields at a liquid-liquid interface have a potential application in solvent extraction processes. In this work, the charge-to-mass ratio of droplets formed in an EHD liquid-liquid extraction system has been investigated experimentally and theoretically. The results reported from the present investigation, extending from the single discrete droplet regime (at low applied voltages) to the dispersed multi-droplet regime (at high applied voltages), indicate that the modified Rayleigh instability model and Vonnegut and Neubauer model can explain maximum droplet charge acquired in liquid-liquid systems, especially the modified Vonnegut and Neubauer model which can predict most of the experimental results when the applied electric field is high enough and EHD forces become dominant.

He, W. [Univ. of Toronto, Ontario (Canada). Dept. of Mechanical Engineering; Chang, J.S.; Baird, M.H.I. [McMaster Univ., Hamilton, Ontario (Canada)

1996-01-01

104

Benefit/Cost Ratio in Systems Engineering: Integrated Models, Tests, Design, and Production  

SciTech Connect

We have previously described our methodology for quantification of risk and risk reduction, and the use of risk, quantified as a dollar value, in the Value Engineering and decision tradeoff process. In this work we extend our example theme of the safety of reactive materials during accidental impacts. We have begun to place the validation of our impact safety model into a systems engineering context. In that sense, we have made connections between the data and the trends in the data, our models of the impact safety process, and the implications regarding confidence levels and reliability based on given impact safety requirements. We have folded this information into a quantitative risk assessment, and shown the assessed risk reduction value of developing an even better model, with more model work or more experimental data or both. Since there is a cost incurred for either model improvement or testing, we have used a Benefit/Cost Ratio metric to quantify this, where Benefit is our quantification of assessed risk reduction, and cost is the cost of the new test data, code development, and model validation. This has left us with further questions posed for our evolving system engineering representation for impact safety and its implications. We had concluded that the Benefit/Cost Ratio for more model validation was high, but such improvement could take several paths. We show our progress along two such paths; simple and high fidelity modeling of the impact safety process, and the implications of our knowledge and assumptions of the probability distribution functions involved. At the other end of the systems engineering scale, we discuss the implications of our linkage from model validation to risk on our production plant operations. Naturally, the nature of most such methodologies is still evolving, and this work represents the views of the authors and not necessarily the views of Lawrence Livermore National Laboratory.

Nitta, C; Logan, R; Chidester, S; Foltz, M F

2004-10-27

105

Deep, Low Mass Ratio Overcontact Binary Systems. XI. V1191 Cygni  

NASA Astrophysics Data System (ADS)

Complete CCD photometric light curves in BV(RI) c bands obtained on one night in 2009 for the short-period close-binary system V1191 Cygni are presented. A new photometric analysis with the 2003 version of the Wilson-Van Hamme code shows that V1191 Cyg is a W-type overcontact binary system and suggests that it has a high degree of overcontact (f = 68.6%) with very low mass ratio, implying that it is at the late stage of overcontact evolution. The absolute parameters of V1191 Cyg are derived using spectroscopic and photometric solutions. Combining new determined times of light minimum with others published in the literature, the period change of the binary star is investigated. A periodic variation, with a period of 26.7 years and an amplitude of 0.023 days, was discovered to be superimposed on a long-term period increase (dP/dt = +4.5(± 0.1) × 10-7 days yr-1). The cyclic period oscillation may be caused by the magnetic activity cycles of either of the components or the light-time effect due to the presence of a third body with a mass of m 3 = 0.77 M sun and an orbital radius of a 3 = 7.6 AU, when this body is coplanar to the orbit of the eclipsing pair. The secular orbital period increase can be interpreted as a mass transfer from the less massive component to the more massive one. With the period increases, V1191 Cyg will evolve from its present low mass ratio, high filled overcontact state to a rapidly rotating single star when its orbital angular momentum is less than three times the total spin angular momentum. V1191 Cyg is too blue for its orbital period and it is an unusual W-type overcontact system with such a low mass ratio and high fill-out overcontact configuration, which is worth monitoring continuously in the future.

Zhu, L. Y.; Qian, S. B.; Soonthornthum, B.; He, J. J.; Liu, L.

2011-10-01

106

The Longperiod Binary Uu-Cancri as a System that has Reversed its Mass Ratio  

NASA Astrophysics Data System (ADS)

UU Cnc is a 96-d binary system (K4 111+?) which has been interpreted as a contact binary, presumably representing the common-envelope stage of evolution. Since this is such a bizarre possibility, we have tested it by using the rotational velocity to determine the mass ratio and by obtaining lUE observations to search for the hot, accreting source that might be expected if the system were semi-detached. The rotational velocity near conjunction, V sin i=22±3 km s-1, based on two independent determinations, requires the optically undetected companion star to be more massive than the K4 giant; the measured mass ratio is 1.47±0.2. The lUE spectra covering the entire orbit show no variation in the ultraviolet continuum greater than 0.3 mag. The source of the ultraviolet continuum is still uncertain. The detected flux in the ultraviolet is lower than expected from a star as massive as the unseen component (M ? 1.6 Msun), unless it is evolved, swollen by accretion, or hidden in a disc. The continuum flux in the ultraviolet is roughly four times that predicted for a normal K4-5 giant or supergiant, and existing lUE spectra of K `giants indicate this excess is outside the range for the star's spectral type. We develop the model in which the system has reversed its mass ratio through a combination of mass loss and exchange. The luminosities of the two components would differ by two orders of magnitude, so most of the light in the optical would be from the K4 giant, as observed. The light-curve solution indicates the spectroscopically undetected star is surrounded by a dark disc which shields it in the optical. The ultraviolet excess probably comes from the central regions of this disc, which cannot be eclipsed. An inclination of about 70° is derived from this restriction, which is consistent with the light curve. Unless the solution is radically different than this, specifically, in the sense of being detached, the limb and gravity darkening of the K giant must be close to the levels expected for a convective star.

Eaton, J. A.

1990-11-01

107

A study on the optimal hydraulic loading rate and plant ratios in recirculation aquaponic system.  

PubMed

The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield was significantly higher in the lower hydraulic loading rate. Fish production, plant growth and percentage nutrient removal were highest at hydraulic loading rate of 1.28 m/day. The ratio of fish to plant production has been calculated to balance nutrient generation from fish with nutrient removal by plants and the optimum ratio was 15-42 gram of fish feed/m(2) of plant growing area. Each unit in RAS was evaluated in terms of oxygen demand. Using specified feeding regime, mass balance equations were applied to quantify the waste discharges from rearing tanks and treatment units. The waste discharged was found to be strongly dependent on hydraulic loading rate. PMID:19819130

Endut, Azizah; Jusoh, A; Ali, N; Wan Nik, W B; Hassan, A

2009-10-09

108

Temperature monitoring system for inductive heater oven  

Microsoft Academic Search

This paper describes numerical model for inductive heating oven and temperature monitoring system for color coating line. For induction heating, the heat generation is concentrated within skin depth so exponentially decaying heat distribution was assumed. To calculate and to monitor the oven exit temperature, measurement system was installed on the inductive heater oven including pyrometer and several thermocouples . The

Wonchul Jung; Jongwoo You; Sangchul Won

2008-01-01

109

CO A-X system for constraining cosmological drift of the proton-electron mass ratio  

NASA Astrophysics Data System (ADS)

The A1?-X1?+ band system of carbon monoxide, which has been detected in six highly redshifted galaxies (z=1.6-2.7), is identified as a probe method to search for possible variations of the proton-electron mass ratio (?) on cosmological time scales. Laboratory wavelengths of the spectral lines of the A-X (v,0) bands for v=0-9 have been determined at an accuracy of ??/?=1.5×10-7 through VUV Fourier-transform absorption spectroscopy, providing a comprehensive and accurate zero-redshift data set. For the (0,0) and (1,0) bands, two-photon Doppler-free laser spectroscopy has been applied at the 3×10-8 accuracy level, verifying the absorption data. Sensitivity coefficients K? for a varying ? have been calculated for the CO A-X bands so that an operational method results to search for ? variation.

Salumbides, E. J.; Niu, M. L.; Bagdonaite, J.; de Oliveira, N.; Joyeux, D.; Nahon, L.; Ubachs, W.

2012-08-01

110

Experimental investigation of power loss coefficients and static pressure ratios in an industrial exhaust ventilation system.  

PubMed

A study tested whether measures of equivalent resistance (X values) and ratios of static pressure (SPratio) for given ducts of contaminant control exhaust ventilation systems were independent of substantial changes to airflow level and to changes to resistance of other ducts within the same full-scale five-branch system. In a factorial study design, four airflow levels were achieved by changing fan rotation rate while resistances to flow for specific branch ducts were changed independently by adjusting slidegate dampers to various settings. For each damper insertion depth (including fully open), the results demonstrated substantial invariance for branch X values (few greater than 5%), SPratio (few greater than 3%), and fraction of airflow to each duct (few greater than 2%). X-values for submains were much less stable, changing by 20% or more with changes to other parts of the system. For the same conditions, hood static pressures changed by as much as 96% (with standard deviation of 40%). The results suggest that before and after values of X and SPratios should be more reliable bases for indicating alterations than comparison of observed static pressures. The stability of airflow distributions with substantial changes in airflow suggests that one could adjust airflow distribution (e.g., with dampers) without considering whether the fan speed was set correctly, leaving fan adjustments for a final step. PMID:10386358

Guffey, S E; Spann, J G

111

Carbon isotope ratios of Phanerozoic marine cements: Re-evaluating the global carbon and sulfur systems  

NASA Astrophysics Data System (ADS)

Original ? 13C values of abiotically precipitated marine cements from a variety of stratigraphic intervals have been used to document secular variations in the ? 13C values of Phanerozoic oceans. These, together with the ° 34S values of coeval marine sulfates, are used to examine the global cycling of carbon and sulfur. It is generally accepted that secular variation in ? 13C and ? 34S values of marine carbonates and sulfates is controlled by balanced oxidation-reduction reactions and that their long-term, steady-state variation can be predicted from the present-day isotopic fractionation ratio (? c/? s) the ratio of the riverine flux of sulfur and carbon ( Fs/ Fc). The predicted slope of the linear relation between ? 13C carb and ? 34S sulfate values is approximately -0.10 to -0.14. However, temporal variation observed in marine cement ? 13C values and the 6345 values of coeval marine sulfates produces a highly significant linear relation ( r2 = 0.80; ? > 95%) with a slope of -0.24; approximately twice the predicted value. This discordance suggests that either the Phanerozoic average riverine Fs/ Fc was 1.6-3.3 times greater than today's estimates or that an additional source of 34S-depleted sulfur or 13C-enriched carbon, other than continental reservoirs, was active during the Phanerozoic. This new relation between marine ? 13C and ? 34S values suggests that the flux of reduced sulfur, iron, and manganese from seafloor hydrothermal systems affects oceanic O2 levels which, in turn, control the oxidation or burial of organic matter, and thus the ? 13C value of marine DIC. Therefore, the sulfur system (driven by seafloor hydrothermal systems) controls the carbon system rather than organic carbon burial controlling the response of ? 34S values (via formation of sedimentary pyrite). Secular variation of marine 87Sr/86Sr ratios and ? 13C values argues for a coupling of ? 34S and ? 34S values to variation in the relative contribution of seafloor hydrothermal and continental weathering fluxes. These trends indicate that the early Paleozoic was dominated by low temperature silicate weathering, whereas the Late Paleozoic to Modern was dominated by high temperature seawater-basalt interactions. Variation in Proterozoic ? 13C carb and ? 34S sulfate values produces a slope that is greater than that of the Phanerozoic ( -0.50 vs. -0.24). This steeper slope is consistent with other geochernical data that indicate relatively high seafloor hydrothermal fluxes during the late Precambrian. We speculate that the dramatic evolutionary changes of the Neoproterozoic-Paleozoic transition occur during a waning of seafloor hydrothermal fluxes and a concomitant decrease in O 2 consumption that permitted the oxygenation of seawater thought to be critical in metazoan evolution.

Carpenter, Scott J.; Lohmann, Kyger C.

1997-11-01

112

Signal-to-noise ratio performance for detection systems of quantum dot multiplexed optical encoding  

NASA Astrophysics Data System (ADS)

The wavelength and intensity of the spectral emission of a group of quantum dots can be altered by varying the size of the quantum dots (wavelength) and the number of the quantum dots (intensity). In this way, information and be encoded into the spectral characteristics of the group of quantum dots emission. This approach has been proposed for the application of tagging thousands of biomolecules as well as replacing barcodes as a means to identify objects. The potential in this system rests in the ability to achieve a high information density. In this paper we model and measure the noise in the readout system that will contribute to the decrease of the information density. We also propose an alternate optical detector as a possibly simpler and cheaper design. Our results demonstrate that the signal-to-noise ratio for both the CCD and photodiode detectors has a linear relationship with time. To achieve comparable SNR, approximately 30dB, in both detectors we note that the CCD-based spectrometer requires integration times on the order of hundreds of milliseconds while the photodiode only requires tens of microseconds.

Goss, K. C.; Potter, M. E.; Messier, G. G.

2010-06-01

113

Air-to-fuel ratio adjusting system for an internal combustion engine  

Microsoft Academic Search

A carburetor for applying air-fuel mixture to an internal combustion engine includes a main passage for applying air-fuel mixture and principally controlling the amount thereof. The air-to-fuel ratio of the air-fuel mixture to be supplied to the engine is detected by an air-to-fuel ratio detector mounted in an exhaust pipe of the engine, and when the detected ratio is lower

T. Hattori; S. Takada; F. Sugi; T. Nakase

1977-01-01

114

The systemic inflammation-based neutrophil-lymphocyte ratio: Experience in patients with cancer.  

PubMed

There is increasing and consistent evidence that cancer-associated inflammation is a key determinant of outcome in patients with cancer. Various markers of inflammation have been examined over the past decade in an attempt to refine stratification of patients to treatment and predict survival. One routinely available marker of the systemic inflammatory response is the neutrophil-lymphocyte ratio (NLR), which is derived from the absolute neutrophil and absolute lymphocyte counts of a full blood count. To date, over 60 studies (>37,000 patients) have examined the clinical utility of the NLR to predict patient outcomes in a variety of cancers. The present systematic review examines and comments on the clinical utility of the NLR. The NLR had independent prognostic value in (a) unselected cohorts (1 study of >12,000 patients), (b) operable disease (20 studies, >4000 patients), (c) patients receiving neoadjuvant treatment and resection (5 studies, >1000 patients), (d) patients receiving chemo/radiotherapy (12 studies, >2000 patients) and (e) patients with inoperable disease (6 studies, >1200 patients). These studies originated from ten different countries, in particular UK, Japan, and China. Further, correlative studies (15 studies, >8500 patients) have shown that NLR is elevated in patients with more advanced or aggressive disease evidenced by increased tumour stage, nodal stage, number of metastatic lesions and as such these patients may represent a particularly high-risk patient population. Further studies investigating the tumour and host-derived factors regulating the systemic inflammatory response, in particular the NLR, may identify novel treatment strategies for patients with cancer. PMID:23602134

Guthrie, Graeme J K; Charles, Kellie A; Roxburgh, Campbell S D; Horgan, Paul G; McMillan, Donald C; Clarke, Stephen J

2013-04-17

115

Effects of Carbon\\/Nitrogen\\/Phosphorus Ratio on Mineralizing Bacterial Population in Aquaculture Systems  

Microsoft Academic Search

The ratio of major fertilizing elements carbon, nitrogen, and phosphorus have immense importance in mineralization and aquatic productivity. It influences microbial activity of soil and water and, thereby, affects the rate of release of nutrients from organic manures. The effects of C\\/N\\/P ratio on different mineralizing bacterial populations were tested for six months in outdoor cement cisterns (180 L). Four

M. Ghosh; N. R. Chattopadhyay

2005-01-01

116

DEEP, LOW MASS RATIO OVERCONTACT BINARY SYSTEMS. IX. V345 GEMINORUM WITH A BRIGHT VISUAL PAIR  

SciTech Connect

CCD photometric observations of the visual binary, V345 Geminorum, obtained from 2007 January 24 to 2009 March 22, are presented. When comparing the light curves in 2007 and 2008, it is found that there appears to be an O'Connell effect in the light curves of 2008. From those observations, two sets of photometric solutions were deduced using the 2003 version of the W-D program. The results indicated that V345 Gem is a low mass ratio overcontact binary with f = 72.9%({+-}3.1%). The asymmetric light curves in 2008 may be attributed to the activity of starspot, whose area is up to 1.55% of the area of the more massive component. The contributions of the third light to the total light are approximately 20% in the BVR bands. The absolute physical parameters for V345 Gem were obtained first. From the log L-log M diagram of the binary-star evolution, the primary component is an evolved star. From the O-C curve for V345 Gem, it is discovered that there exists a long-term period increase with a cyclic variation. The period and amplitude of the cyclic variation are P {sub 3} = 646.7({+-}0.7) day and A = 0fd0019({+-}0fd0002), which may be caused by the light-time effect via the assumed third body. If it is true, the visual binary V345 Gem may be a quadruple star. The kind of additional component may remove angular momentum from the central system, which may play an important role for the formation and evolution of the binary. The secular period increases at a rate of dP/dt = +5.88 x 10{sup -8} d yr{sup -1}, indicating that the mass transfers from the less massive component to the more massive component. With mass transferring, the orbital angular momentum decreases while the spin angular momentum increases. When J {sub spin}/J {sub orb} > 1/3, this kind of deep, low mass ratio overcontact binary with secular period increase may evolve into a rapid-rotating single star.

Yang, Y.-G. [School of Physics and Electric Information, Huaibei Coal Industry Teachers College, 235000 Huaibei, Anhui Province (China); Qian, S.-B.; Zhu, L.-Y.; He, J.-J. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, 650011 Kunming (China)], E-mail: yygcn@163.com

2009-08-15

117

Effects of different eddy covariance correction schemes on energy balance closure and comparisons with the modified Bowen ratio system  

Microsoft Academic Search

Eddy covariance (EC) and modified Bowen ratio (MBR) systems have been shown to yield subtly different estimates of sensible heat (H), latent heat (LE), and CO2 fluxes (Fc). Our study analyzed the discrepancies between these two systems by first considering the role of the data processing algorithm used to estimate fluxes using EC and later examining the effects of atmospheric

Adam Wolf; Nick Saliendra; Kanat Akshalov; Douglas A. Johnson; Emilio Laca

2008-01-01

118

Effects of Different Eddy Covariance Correction Schemes on Energy Balance Closure and Comparisons with the Modified Bowen Ratio System  

Technology Transfer Automated Retrieval System (TEKTRAN)

Eddy covariance (EC) and modified Bowen ratio (MBR) systems typically yield subtly different estimates of H, LE, and Fc. Our study analyzed the discrepancies between EC and MBR systems by first considering the role of the data processing algorithm used to estimate fluxes using EC and later examinin...

119

Systemic acid load from the diet affects maximal exercise respiratory exchange ratio  

PubMed Central

Background A maximal exercise respiratory exchange ratio (RERmax) ?1.10 is commonly used as a criterion to determine if a “true” maximal oxygen uptake (VO2max) has been attained during maximal-effort exercise testing. Because RERmax is heavily influenced by CO2 production from acid buffering during maximal exercise, we postulated that dietary acid load, which affects acid-base regulation, might contribute to variability in RERmax. Purpose To determine if a habitual dietary intake that promotes systemic alkalinity results in higher RERmax during VO2max testing. Methods Sedentary men and women (47-63y, n=57) with no evidence of cardiovascular disease underwent maximal graded treadmill exercise tests. VO2max and RERmax were measured with indirect calorimetry. Habitual diet was assessed for its long-term effect on systemic acid-base status by performing nutrient analysis of food diaries and using this information to calculate the potential renal acid load (PRAL). Participants were grouped into tertiles based on PRAL. Results The lowest PRAL tertile (alkaline PRAL) had higher RERmax values (1.21±0.01, p?0.05) than the middle tertile (1.17±0.01) and highest PRAL tertile (1.15±0.01). There were no significant differences (all p?0.30) among PRAL tertiles for RER at submaximal exercise intensities of 70%, 80%, or 90% VO2max. After controlling for age, sex, VO2max, and maximal heart rate (HRmax), regression analysis demonstrated that 19% of the variability in RERmax was attributed to PRAL (r=?0.43, p=0.001). Unexpectedly, HRmax was lower (p?0.05) in the low PRAL tertile (164±3 beats/min) versus the highest PRAL tertile (173±3 beats/min). Conclusion These results suggest that individuals on a diet that promotes systemic alkalinity may more easily achieve the RERmax criterion of ?1.10 which might lead to false-positive conclusions about achieving maximal effort and VO2max during graded exercise testing.

Niekamp, Katherine; Zavorsky, Gerald S.; Fontana, Luigi; McDaniel, Jennifer L; Villareal, Dennis T; Weiss, Edward P

2013-01-01

120

Evaluation of an automated safety surveillance system using risk adjusted sequential probability ratio testing  

PubMed Central

Background Automated adverse outcome surveillance tools and methods have potential utility in quality improvement and medical product surveillance activities. Their use for assessing hospital performance on the basis of patient outcomes has received little attention. We compared risk-adjusted sequential probability ratio testing (RA-SPRT) implemented in an automated tool to Massachusetts public reports of 30-day mortality after isolated coronary artery bypass graft surgery. Methods A total of 23,020 isolated adult coronary artery bypass surgery admissions performed in Massachusetts hospitals between January 1, 2002 and September 30, 2007 were retrospectively re-evaluated. The RA-SPRT method was implemented within an automated surveillance tool to identify hospital outliers in yearly increments. We used an overall type I error rate of 0.05, an overall type II error rate of 0.10, and a threshold that signaled if the odds of dying 30-days after surgery was at least twice than expected. Annual hospital outlier status, based on the state-reported classification, was considered the gold standard. An event was defined as at least one occurrence of a higher-than-expected hospital mortality rate during a given year. Results We examined a total of 83 hospital-year observations. The RA-SPRT method alerted 6 events among three hospitals for 30-day mortality compared with 5 events among two hospitals using the state public reports, yielding a sensitivity of 100% (5/5) and specificity of 98.8% (79/80). Conclusions The automated RA-SPRT method performed well, detecting all of the true institutional outliers with a small false positive alerting rate. Such a system could provide confidential automated notification to local institutions in advance of public reporting providing opportunities for earlier quality improvement interventions.

2011-01-01

121

Association of microalbuminuria and the urine albumin-to-creatinine ratio with systemic disease in cats  

Microsoft Academic Search

OBJECTIVE: To determine the diagnostic usefulness of semiquantitative and quantitative microalbuminuria assays and urine albumin-to-creatinine (UAC) ratio for detecting disease in cats. DESIGN: Prospective study. ANIMALS: 441 cats evaluated at a veterinary teaching hospital. PROCEDURES: Urine samples from cats for which a complete medical record was available were included. Urine dipstick results, urine protein-to-creatinine ratios (cutoffs, 0.1 and 0.4), semiquantitative

Jacqueline C. Whittemore; Zona Miyoshi; Wayne A. Jensen; Steven V. Radecki; Michael R. Lappin

2007-01-01

122

A sex-ratio Meiotic Drive System in Drosophila simulans. II: An X-linked Distorter  

PubMed Central

The evolution of heteromorphic sex chromosomes creates a genetic condition favoring the invasion of sex-ratio meiotic drive elements, resulting in the biased transmission of one sex chromosome over the other, in violation of Mendel's first law. The molecular mechanisms of sex-ratio meiotic drive may therefore help us to understand the evolutionary forces shaping the meiotic behavior of the sex chromosomes. Here we characterize a sex-ratio distorter on the X chromosome (Dox) in Drosophila simulans by genetic and molecular means. Intriguingly, Dox has very limited coding capacity. It evolved from another X-linked gene, which also evolved de nova. Through retrotransposition, Dox also gave rise to an autosomal suppressor, not much yang (Nmy). An RNA interference mechanism seems to be involved in the suppression of the Dox distorter by the Nmy suppressor. Double mutant males of the genotype dox; nmy are normal for both sex-ratio and spermatogenesis. We postulate that recurrent bouts of sex-ratio meiotic drive and its subsequent suppression might underlie several common features observed in the heterogametic sex, including meiotic sex chromosome inactivation and achiasmy.

Tao, Yun; Araripe, Luciana; Kingan, Sarah B; Ke, Yeyan; Xiao, Hailian; Hartl, Daniel L

2007-01-01

123

Influence of concentration ratios on the effectiveness of binary systems of antioxidants  

SciTech Connect

This paper studies the effect of concentration ratios in a mixture of antioxidants of this type on the effectiveness of their activity in the conditions of cumene oxidation at 60 degrees C. The action of inhibitors in a mixture of b-naphthol and a-naphthylamine has additive character. In a mixture of ionol and a-naphthylamine, the onset of antagonism is observed. Synergism appears in mixtures of b-naphthol with ionol. The maximum inhibiting action is attained with a 3:5 ratio of the antioxidants.

Pisareva, S.I.; Sidorenko, A.A.

1985-07-01

124

Analysis on the influences of range-gated underwater laser imaging system parameters on the signal to noise ratio  

NASA Astrophysics Data System (ADS)

Range-gated underwater laser imaging system is a kind of underwater photoelectric imaging system which is based on the principle of time label for target. Through controlling the imaging time of photoelectric equipment precisely, it can effectively restrain the backscatter of water, having longer detective distance than generic ones. A range-gated underwater laser imaging system consists of pulse laser illumination system, photoelectric imaging system (ICCD) and control system commonly. When the moment and the time of ICCD opening gate are given, the lights that could be received by ICCD include the backscatter of water, the direct component and forward scatter of reflected light of the target in the imaging processing of range-gated underwater laser imaging system. Computing model of light energy received by ICCD was built in this paper. The direct component and forward scatter of reflected light energy were analyzed and the calculation methods based on PSF theory were studied. The backscatter light energy of water was calculated through water layering. The signal to noise ratio of range-gated underwater laser imaging system was defined. The impact of target range, target reflection ratio, ICCD gating width and water attenuation coefficient on the signal to noise ratio were analyzed and simulation results were given.

Ge, Wei-long; Hua, Liang-hong; Han, Hong-wei

2013-09-01

125

An electrically tunable optical zoom system using two composite liquid crystal lenses with a large zoom ratio.  

PubMed

An electrically tunable-focusing optical zoom system using two composite LC lenses with a large zoom ratio is demonstrated. The optical principle is investigated. To enhance the electrically tunable focusing range of the negative lens power of the LC lens for a large zoom ratio, we adopted two composite LC lenses. Each composite LC lens consists of a sub-LC lens and a planar polymeric lens. The zoom ratio of the optical zooming system reaches ~7.9:1 and the object can be zoomed in or zoomed out continuously at the objective distance of infinity to 10 cm. The potential applications are cell phones, cameras, telescope and pico projectors. PMID:21369302

Lin, Yi-Hsin; Chen, Ming-Syuan; Lin, Hung-Chun

2011-02-28

126

Universality and quantization of the power-to-heat ratio in nanogranular systems  

NASA Astrophysics Data System (ADS)

We study heating and dissipation effects in granular nanosystems in the regime of weak coupling between the grains. We focus on the cotunneling regime and solve the heat-dissipation problem in an array of grains exactly. We show that the power to heat ratio has a universal quantized value, which is geometrically protected: It depends only on the number of grains.

Chtchelkatchev, N. M.; Glatz, A.; Beloborodov, I. S.

2013-09-01

127

Fuel Character Effects on Current, High Pressure Ratio, Can-Type Turbine Combustion Systems.  

National Technical Information Service (NTIS)

The effect of limited fuel property variation on the performance of current, high pressure-ratio, can-type combustors was evaluated. The TF41 turbofan combustor was employed. This combustor has conventional, dual-orifice fuel injection and film cooling. T...

R. E. Vogel D. L. Troth A. J. Verdouw

1980-01-01

128

Modeling of temperature and humidity ratio in an automobile passenger compartment for automobile air conditioning systems  

Microsoft Academic Search

This study investigates thermal dynamic modeling of a passenger compartment in an air conditioned automobile equipped with HVAC (heating, ventilation, and air conditioning). In particular, dynamics of temperature and humidity ratio, both critical to passenger comfort, in the passenger compartment are examined. By analyzing enthalpy change during an automobile air conditioning circulation cycle on a psychrometric chart, heat exchange between

Sheng-Luen Chung; Chung-Lun Li

2011-01-01

129

The salivary alpha amylase over cortisol ratio as a marker to assess dysregulations of the stress systems.  

PubMed

Different factors have been associated with changes in the regulation of the two major stress response systems of the human body, the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis. Changes in these systems have been associated with various (psycho)pathologies across adulthood, and are thus frequently assessed within the context of allostatic load. Early Life Adversity (ELA) has been identified as one such factor. Individuals with histories of ELA show evidence of elevated basal and reactive salivary alpha amylase (sAA) levels (a marker of SNS activity), blunted cortisol levels (a marker of HPA axis activity), and an asymmetrical relationship between the two variables. However, variable methods used in the past to measure each variable, and the relationship between the two systems, prevent us from drawing firm conclusions. This preliminary study investigated whether the ratio of reactive sAA over reactive cortisol would be more informative to investigate the relationship between the two stress systems than the ratio of cortisol over sAA, or either marker alone, and whether there is a systematic link between this marker and subjective indexes of chronic stress and depression. We studied this in a total of 37 subjects (n=20 with signs of early life adversity and n=17 without) exposed to the Trier social stress test. Using a specific formula to determine the ratio of sAA over cortisol, we found a systematically stronger positive relationship with indexes of chronic stress and depression when compared to cortisol over sAA, or either marker alone. Our findings suggest that the ratio of sAA over cortisol might be a better marker of stress systems dysregulation than the ratio of cortisol over sAA, sAA or cortisol alone. The usefulness of this marker for other chronic stress states as found in allostatic load is discussed. PMID:22019784

Ali, Nida; Pruessner, Jens C

2011-10-12

130

Calibration of a Monochromator/Spectrometer System for the Measurement of Photoelectron Angular Distributions and Branching Ratios.  

National Technical Information Service (NTIS)

We describe the techniques used in calibrating a monochromator/spectrometer system for gas-phase photoelectron angular distribution and branching ratio measurements. We report a self-consistent set of values for the Ne 2p, Ar 3p, Kr 4p/sub 3/2/ and 4p/sub...

S. H. Southworth A. C. Parr J. E. Hardis J. L. Dehmer D. M. P. Holland

1985-01-01

131

Temporal variation in the pollen:ovule ratios of Clarkia (Onagraceae) taxa with contrasting mating systems: field populations.  

PubMed

Among plants, pairs of selfing vs. outcrossing sister taxa provide interesting systems in which to test predictions concerning the magnitude and direction of temporal changes in sex allocation. Although resource availability typically declines towards the end of the growing season for annual taxa, temporal changes in mating opportunities depend on mating system and should change less in selfing taxa. Consequently, given that the pollen:ovule (P:O) ratio of flowers reflects the investment in (and potential fitness pay-off due to) male vs. female function, we predicted that the P:O ratio should also be less variable among and within selfers than in closely related outcrossers. To test these predictions, we measured temporal changes in sex allocation in multiple field populations of two pairs of sister taxa in the annual flowering plant genus Clarkia (Onagraceae). In the outcrossing Clarkia unguiculata and the selfing Clarkia exilis, ovule production declined similarly from early to late buds, whereas pollen production remained constant or increased in the outcrosser but remained constant or decreased in the selfer. Consequently, the P:O ratio increased within unguiculata populations but marginally increased or stayed constant in exilis populations. In all populations of the selfing Clarkia xantiana spp. parviflora and the outcrossing C. x. spp. xantiana, both ovule and pollen production per flower declined over time. The effects of these declines on the P:O ratio, however, differed between subspecies. In each xantiana population, the mean P:O ratio did not differ between early and late flowers, although individuals varied greatly in the direction and magnitude of phenotypic change. By contrast, parviflora populations differed in the mean direction of temporal change in the P:O ratio. We found little evidence to support our initial predictions that the P:O ratio of the selfing taxa will consistently vary less than in outcrossing taxa. PMID:18005114

Delesalle, V A; Mazer, S J; Paz, H

2007-11-12

132

Technique to measure CO 2 mixing ratio in small flasks with a bellows\\/IRGA system  

Microsoft Academic Search

We developed a laboratory method to obtain high precision CO2 mixing ratios in air samples contained in 100ml glass flasks, which involves extracting air from the flask into a pre-evacuated manifold containing a variable-volume metal bellows. Compressed air from the bellows is then routed to a non-dispersive infrared gas analyzer (IRGA). Tests indicate that this configuration has an overall accuracy

D. R. Bowling; C. S. Cook; J. R. Ehleringer

2001-01-01

133

Real-Time Measurement of Oil Circulation Ratio in CO2 Heat Pump System Using Optical Method  

NASA Astrophysics Data System (ADS)

The lubricating oil in the refrigerant flow in a CO2 heat pump system has a great influence on cycle performance. In order to measure the OCR (Oil circulation ratio), a mixing chamber and a visual vessel were installed at the outlet of the gas-cooler. By mixing the oil and refrigerant, the liquid mixture of oil and refrigerant becomes cloudy at the outlet of the gas-cooler. By measuring the infrared ray transmittance of the oil-refrigerant liquid mixture, it was found that the transmittance decreases with an increase in the oil circulation ratio. For this reason, it is found that, in spite of immiscible refrigerant and oil, the measurement of the oil circulation ratio is possible by measuring the transmittance of infrared ray at the outlet of the gas-cooler.

Takigawa, Ryusuke; Shimizu, Takao; Matsusaka, Yukio; Gao, Lei; Honda, Tomohiro

134

New and conventional evaporative systems in concentrating nitrogen samples prior to isotope-ratio analysis  

Microsoft Academic Search

Studies were conducted to quantify and compare the efficiencies of various evaporative systems used in evaporating ¹⁵N samples prior to mass spectrometric analysis. Two new forced-air systems were designed and compared with a conventional forced-air system and with an open-air dry bath technique for effectiveness in preventing atmospheric contamination of evaporating samples. The forced-air evaporative systems significantly reduced the time

R. W. Lober; J. D. Reeder; L. K. Porter

2009-01-01

135

Spectral Ratio Estimates for Site Effects on the Horst-Graben System in West Turkey  

NASA Astrophysics Data System (ADS)

Recordings of micro- and moderate-size local earthquakes have been used to quantify site effects in the central-west Turkey which contains one of the world's best examples of a rapid intra-continental extension with its high population and industrial potential. We analyzed 436 earthquakes with local magnitudes ranging between 2.0 and 5.6 using three component digital recordings from 32 stations. Site functions were obtained using two different spectral ratio approaches (horizontal to vertical spectral ratio, HVSR, and standard spectral ratio, SSR). HVSR estimates of transverse and radial S-waves were compared with one another. Epicentral distance, magnitude and back-azimuth dependencies of site functions were also evaluated. In general, HVSR values from transverse and radial S-waves are similar within a factor of 2. The back-azimuth dependencies of transverse S-wave HVSR results are more significant than distance and magnitude dependencies. On the other hand, averaging of transverse and radial S-wave HVSR results eliminates systematic back-azimuth dependencies caused by source radiation effects. Distributions of HVSR estimates along ~N-S linear array, which traversed main grabens in the region with a station spacing of 3-4 km, reflect subsurface geological complexities in the region. The sites located near the basin edges are characterized by broader HVSR curves. Broad HVSR peaks could be attributed to the complexity of wave propagation related to significant 2D/3D velocity variations at the sediment-bedrock interface near the basin edges. The results also show that, even if the site is located on a horst, the presence of weathered zones along the surface could cause moderate frequency dependent site effects. Comparison of HVSR and SSR estimates for the stations on the graben sites showed that SSR estimates give larger values at lower frequencies which could be attributed to lateral variations in regional velocity and attenuation values caused by basin geometry and edge effects.

Akyol, N?hal; Kurtulmu?, Tevf?k Özgür; Çamyildiz, Murat; Güngör, Tal?p

2013-03-01

136

Planarians maintain a constant ratio of different cell types during changes in body size by using the stem cell system.  

PubMed

Planarians change in body size depending upon whether they are in feeding or starving conditions. To investigate how planarians regulate this flexible system, the numbers of total cells and specific cell types were counted and compared among worms 2 mm to 9 mm in body length. The total cell number increased linearly with increasing body length, but the ratio of cell numbers between the head and the trunk portion was constant (1:3). Interestingly, counting the numbers of specific neurons in the eye and brain after immunostaining using cell type-specific antibodies revealed that the ratio between different neuron types was constant regardless of the brain and body size. These results suggest that planarians can maintain proportionality while changing their body size by maintaining a constant ratio of different cell types. To understand this system and reveal how planarians restore the original ratio during eye and brain regeneration, the numbers of specialized cells were Investigated during regeneration. The results further substantiate the existence of some form of "counting mechanism" that has the ability to regulate both the absolute and relative numbers of different cell types in complex organs such as the brain during cell turnover, starvation, and regeneration. PMID:19968467

Takeda, Hiroyuki; Nishimura, Kaneyasu; Agata, Kiyokazu

2009-12-01

137

The explosion energy of early stellar populations: the Fe-peak element ratios in low-metallicity damped Ly? systems  

NASA Astrophysics Data System (ADS)

The relative abundances of the Fe-peak elements (Ti-Zn) at the lowest metallicities are intimately linked to the physics of core-collapse supernova explosions. With a sample of 25 very metal poor damped Ly? systems (DLAs), we investigate the trends of the Fe-peak element ratios with metallicity. For nine of the 25 DLAs, a direct measurement (or useful upper limit) of one or more of the Ti, Cr, Co, Ni, Zn/Fe abundance ratios could be determined from detected absorption lines. For the remaining systems (without detections), we devised a new form of spectral stacking to estimate the typical Fe-peak element ratios of the DLA population in this metallicity regime. We compare these data to analogous measurements in metal-poor stars of the Galactic halo and to detailed calculations of explosive nucleosynthesis in metal-free stars. We conclude that most of the DLAs in our sample were enriched by stars that released an energy of ?1.2 × 1051 erg when they exploded as core-collapse supernovae. Finally, we discuss the exciting prospect of measuring Fe-peak element ratios in DLAs with Fe/H < 1/1000 of solar when 30-m class telescopes become available. Only then will we be able to pin down the energy that was released by the supernovae of the first stars.

Cooke, Ryan; Pettini, Max; Jorgenson, Regina A.; Murphy, Michael T.; Rudie, Gwen C.; Steidel, Charles C.

2013-05-01

138

influence of concentration and mannuronate/guluronate [correction of gluronate] ratio on steady flow properties of alginate aqueous systems.  

PubMed

Steady flow properties were measured at various concentrations for aqueous systems of alignates with different mannuronate/gluronate (M/G) ratios using a cone-plate type rheometer. The flow curve (a plot of shear stress vs. shear rate) shows a plateau region, which is ascribed to a heterogeneous structure, at low shear rate. This plateau region is more noticeable in the G-rich systems than in the M-rich systems. On the other hand, the flow curves for the systems with the same molecular weight but different M/G ratios are congruent in the high shear rate region. The zero shear viscosity can be reduced by the segment contact parameter, cMw, for the alginates with the same M/G ratio but different molecular weights. The zero shear viscosity is proportional to cMw in a low concentration region and is proportional to (cMw)3.4 at relatively high concentrations. The critical value of cMw for which the zero shear viscosity changes from proportionality with cMw to proportionality with (cMw)3.4 is ca. 900. PMID:1306367

Matsumoto, T; Kawai, M; Masuda, T

139

Pollen grain numbers, ovule numbers and pollen-ovule ratios in Caryophylloideae: correlation with breeding system, pollination, life form, style number, and sexual system  

Microsoft Academic Search

Pollen-ovule ratios (P\\/O) were measured for 79 species of Caryophylloideae (Agrostemma, Dianthus, Saponaria, Silene, and Vaccaria). We analyzed if these features are best correlated with (1) the breeding system (outcrossing or selfing), (2) diurnal or nocturnal pollination, (3) life form (annual versus perennial), (4) style number, (5) the sexual system (hermaphroditism, gynodioecism, dioecism), or (6) the taxonomy of species. According

A. Jürgens; T. Witt; G. Gottsberger

2002-01-01

140

Individual burner fuel\\/air ratio control optical adaptive feedback control system. Final report  

Microsoft Academic Search

Conventional combustion control systems for multiburner installations which rely on monitoring the average COâ and\\/or Oâ content of the gases have a number of inherent limitations on their ability to maintain efficient plant operation. Air infiltration into the flue or sampling lines has the same effect as an instrumental error in causing the control system to adjust the stoichiometry to

J. M. Beer; M. T. Jacques; J. D. Teare

1982-01-01

141

Tuning the current ratio of a CPV system to maximize the energy harvesting in a particular location  

NASA Astrophysics Data System (ADS)

A method based on experimental data is proposed to optimize the energy harvesting of a silicone-on-glass Fresnel-lens based CPV system. It takes into account the spectral variations along the year in a particular location as well as the thermal and spectral sensitivities of the optics and solar cell. In addition, different alternatives to tune the top/middle subcells current ratio in a CPV module are analyzed and their capacity to maximize the annually produced energy is quantified.

Victoria, M.; Askins, S.; Nuñez, R.; Domínguez, C.; Herrero, R.; Antón, I.; Sala, G.; Ruíz, J. M.

2013-09-01

142

Influence of D/A ratio on photovoltaic performance of a highly efficient polymer solar cell system.  

PubMed

A new copolymer PIDTDTQx based on indacenodithiophene and quinoxaline is synthesized and characterized. The correlation between the D/A ratio, mobility, and photovoltaic properties, as well as morphology of the D/A blend based on a PIDTDTQx:PC(70) BM system is investigated. The power conversion efficiency of the polymer solar cells based on PIDTDTQx/PC(70) BM (1:4, w/w) reaches 7.51%. PMID:23044822

Guo, Xia; Zhang, Maojie; Tan, Jiahui; Zhang, Shaoqing; Huo, Lijun; Hu, Wenping; Li, Yongfang; Hou, Jianhui

2012-10-09

143

Anthropic selection of a Solar System with a high 26Al\\/27Al ratio: Implications and a possible mechanism  

Microsoft Academic Search

Since our technological civilisation depends on our planet's properties, anthropic selection can explain the close match between the high 26Al\\/27Al ratios in the earliest Solar System solids, which are difficult to produce in models of star-formation, and the limiting value required to cause (the widely observed) thermal processing of planetesimals. We suggest that volatile loss on heating of planetesimals favours

J. D. Gilmour; C. A. Middleton

2009-01-01

144

Anthropic selection of a Solar System with a high 26Al\\/ 27Al ratio: Implications and a possible mechanism  

Microsoft Academic Search

Since our technological civilisation depends on our planet's properties, anthropic selection can explain the close match between the high 26Al\\/27Al ratios in the earliest Solar System solids, which are difficult to produce in models of star-formation, and the limiting value required to cause (the widely observed) thermal processing of planetesimals. We suggest that volatile loss on heating of planetesimals favours

J. D. Gilmour; C. A. Middleton

2009-01-01

145

Low-complexity selected mapping schemes for peak-to-average power ratio reduction in OFDM systems  

Microsoft Academic Search

Orthogonal frequency-division multiplexing (OFDM) is an attractive transmission technique for high-bit-rate communication systems. One major drawback of OFDM is the high peak-to-average power ratio (PAPR) of the transmitter's output signal. The selected mapping (SLM) approach provides good performance for PAPR reduction, but it requires a bank of inverse fast Fourier transforms (IFFTs) to generate a set of candidate transmission signals,

Chin-Liang Wang; Ouyang Yuan

2005-01-01

146

A Novel Approach to Instrumentation and Application for Oil Concentration Ratio Measurement in Refrigeration System  

NASA Astrophysics Data System (ADS)

A new instrument has been developed for an on-line real-time measurement of oil circulating rate in refrigeration system utilizing a ultra-violet light absorption behavior of oil. A dual optical path configuration is introduced to the flow cell of this instrument,and it allows the instrument to perform dual beam absorbance measurement which contributes to provide quite stable and precise result. This instrument is applied on OCR measurement on several refrigeration system in transient state.

Kutsuna, Kiyoharu; Nabeta, Teiichi; Wada, Akio

147

Garnet forming solid state reactions in FeYCaZrO systems with different Y-Fe ratios  

NASA Astrophysics Data System (ADS)

Solid state reactions in the Fe2O3-Y2O3-CaCO3-ZrO2 mixtures with different Y-Fe ratios (0 < Fe2O3 < 4.75; 3.25 Y2O3; 1.0 CaCO3; 1.0 ZrO2 molar ratio) sintered at 700-1400°C were investigated by x-ray diffraction and DTG(M) methods. The DTG(M) method proved to be very effective in detecting very small amounts of magnetic constituents in the sample. The most interesting features of the reactions are the following: - At iron contents higher than 2.75 molar ratio in the temperature region 1200-1400°C Ca and Zr containing garnets are formed. - In mixtures with a Fe2O3 content less than 2.75 molar ratio the formation of orthoferrite is preferred. - A new Y2O3-type phase (Y2O'3) is the dominant component in systems with a low iron content.

Sztaniszláv, A.; Balla, M.; Farkas-Jahnke, M.

1989-09-01

148

The exponential eigenmodes of the carbon-climate system, and their implications for ratios of responses to forcings  

NASA Astrophysics Data System (ADS)

Several basic ratios of responses to forcings in the carbon-climate system are observed to be relatively steady. Examples include the CO2 airborne fraction (the fraction of the total anthropogenic CO2 emission flux that accumulates in the atmosphere) and the ratio T/QE of warming (T) to cumulative total CO2 emissions (QE). This paper explores the reason for such near-constancy in the past, and its likely limitations in future. The contemporary carbon-climate system is often approximated as a set of first-order linear systems, for example in response-function descriptions. All such linear systems have exponential eigenfunctions in time (an eigenfunction being one that, if applied to the system as a forcing, produces a response of the same shape). This implies that, if the carbon-climate system is idealised as a linear system (Lin) forced by exponentially growing CO2 emissions (Exp), then all ratios of responses to forcings are constant. Important cases are the CO2 airborne fraction (AF), the cumulative airborne fraction (CAF), other CO2 partition fractions and cumulative partition fractions into land and ocean stores, the CO2 sink uptake rate (kS, the combined land and ocean CO2 sink flux per unit excess atmospheric CO2), and the ratio T/QE. Further, the AF and the CAF are equal. Since the Lin and Exp idealisations apply approximately to the carbon-climate system over the past two centuries, the theory explains the observed near-constancy of the AF, CAF and T/QE in this period. A nonlinear carbon-climate model is used to explore how future breakdown of both the Lin and Exp idealisations will cause the AF, CAF and kS to depart significantly from constancy, in ways that depend on CO2 emissions scenarios. However, T/QE remains approximately constant in typical scenarios, because of compensating interactions between CO2 emissions trajectories, carbon-climate nonlinearities (in land-air and ocean-air carbon exchanges and CO2 radiative forcing), and emissions trajectories for non-CO2 gases. This theory establishes a basis for the widely assumed proportionality between T and QE, and identifies the limits of this relationship.

Raupach, M. R.

2013-01-01

149

California bearing ratio behavior of soil-stabilized class F fly ash systems  

SciTech Connect

Fly ash is a finely divided mineral residue resulting from the combustion of coal in power plants that occupies large extents of land and also causes environmental problems. Hence, concerted attempts are being made to effectively use fly ash in an environmentally friendly way instead of dumping. Several studies have been carried out for its bulk utilization, such as its addition to improve the California bearing ratio (CBR) of soil in roads and embankments. But a thorough mixing of fly ash with soil may not be possible in the field. Hence a study has been carried out on the CBR behavior of black cotton soil and Raichur fly ash (which is class F) in layers and compared with the same in mixes. The results show that the CBR values of soil-fly ash mixes are better than layers, as expected. To improve the strength of layers, cement is used as an additive to fly ash. The results show that black cotton soil can be improved with stabilized fly ash, solving its strength problem as well as the disposal problem of fly ash.

Leelavathamma, B.; Mini, K.M.; Pandian, N.S. [Indian Institute for Science, Bangalore (India). Dept. for Civil Engineering

2005-11-01

150

Local dynamics of a fast-evolving sex-ratio system in Drosophila simulans.  

PubMed

By distorting Mendelian transmission to their own advantage, X-linked meiotic drive elements can rapidly spread in natural populations, generating a sex-ratio bias. One expected consequence is the triggering of a co-evolutionary arms race between the sex chromosome that carries the distorter and suppressors counteracting its effect. Such an arms race has been theoretically and experimentally established and can have many evolutionary consequences. However, its dynamics in contemporary populations is still poorly documented. Here, we investigate the fate of the young X-linked Paris driver in Drosophila simulans from sub-Saharan Africa to the Middle East. We provide the first example of the early dynamics of distorters and suppressors: we find consistent evidence that the driving chromosomes have been rising in the Middle East during the last decade. In addition, identical haplotypes are at high frequencies around the two co-evolving drive loci in remote populations, implying that the driving X chromosomes share a recent common ancestor and suggesting that East Africa could be the cradle of the Paris driver. The segmental duplication associated with drive presents an unusual structure in West Africa, which could reflect a secondary state of the driver. Together with our previous demonstration of driver decline in the Indian Ocean where suppression is complete, these data provide a unique picture of the complex dynamics of a co-evolutionary arms race currently taking place in natural populations of D. simulans. PMID:24118375

Bastide, Héloïse; Gérard, Pierre R; Ogereau, David; Cazemajor, Michel; Montchamp-Moreau, Catherine

2013-10-05

151

36Cl/Cl ratios in geothermal systems: preliminary measurements from the Coso Field  

SciTech Connect

The {sub 36}Cl/Cl isotopic composition of chlorine in geothermal systems can be a useful diagnostic tool in characterizing hydrologic structure, in determining the origins and age of waters within the systems, and in differentiating the sources of chlorine (and other solutes) in the thermal waters. The {sub 36}Cl/Cl values for several geothermal water samples and reservoir host rock samples from the Coso, California geothermal field have been measured for these purposes. The results indicate that most of the chlorine is not derived from the dominant granitoid that host the geothermal system. If the chlorine was originally input into the Coso subsurface through meteoric recharge, that input occurred at least 1-1.25 million years ago. The results suggest that the thermal waters could be connate waters derived from sedimentary formations, presumably underlying and adjacent top the granitic rocks, which have recently migrated into the host rocks. Alternatively, most of the chlorine but not the water, may have recently input into the system from magmatic sources. In either case, the results indicate that most of the chlorine in the thermal waters has existed within the granitoid host rocks for no more than about 100,00-200,00 years. this residence time for the chlorine is similar to residence times suggested by other researchers for chlorine in deep groundwaters of the Mono Basin north of the Coso field.

Nimz, G.J.; Moore, J.N.; Kasameyer, P.W.

1997-07-01

152

RELATIONSHIP BETWEEN HVAC SYSTEM OPERATION, AIR EXCHANGE RATE, AND INDOOR-OUTDOOR PARTICULATE MATTER RATIOS  

EPA Science Inventory

Measurements of duty cycle , the fraction of time the heating and cooling (HVAC) system was operating, were made in each participant's home during the spring season of the RTP Particulate Matter Panel Study. A miniature temperature sensor/data logger combination placed on the ...

153

Evaluation of the water-effect ratio procedure for metals in a riverine system  

SciTech Connect

Site-specific metal standards were determined for a part of the lower Lehigh River using the US Environmental Protection Agency`s water-effect ratio (WER) procedure. The WERs were based on laboratory and site water testing of the species Ceriodaphnia dubia and Pimephales promelas (fathead minnow) and five metals (copper, cadmium, lead, silver, and zinc) during four different months. Both species generally exhibited similar patterns in WERs. The greatest variability between the two species was observed for copper, silver, and lead. Ceriodaphnia yielded a lower mean WER than the fathead minnow for lead and zinc and WERs similar to those of the fathead minnow for copper, cadmium, and silver. The species more sensitive to a given metal did not always exhibit a higher WER, as had been previously assumed. A comparison of final WER calculations indicated that the geometric mean WER was typically higher than the final WER obtained using the 1994 guidance. For most metals, site water toxicity was reduced due to nonacutely toxic dissolved metal. Copper yielded the highest final WER regardless of the calculation method used. Regression analyses indicated that the copper WER was directly related, and the cadmium WER inversely related, to effluent concentration. Copper, lead, and silver WERs were related to site water pH. Cadmium and lead WERs were related to pH and dissolved solids. Zinc WERs were unrelated to any of the water quality variables measured and were similar among site water samples. The results suggest it is prudent to use two species in WER testing and different site water samples to derive a final WER, particularly at sites that are not effluent dominated.

Diamond, J.M. [Tetra Tech, Inc., Owings Mills, MD (United States); Koplish, D.E.; McMahon, J. III; Rost, R. [Bureau of Water Resources, Allentown, PA (United States)

1997-03-01

154

Selenium stable isotope ratios in California agricultural drainage water management systems  

USGS Publications Warehouse

Selenium stable isotope ratios are known to shift in predictable ways during various microbial, chemical, and biological processes, and can be used to better understand Se cycling in contaminated environments. In this study we used Se stable isotopes to discern the mechanisms controlling the transformation of oxidized, aqueous forms of Se to reduced, insoluble forms in sediments of Se-affected environments. We measured 80Se/76Se in surface waters, shallow ground waters, evaporites, digested plants and sediments, and sequential extracts from several sites where agricultural drainage water is processed in the San Joaquin Valley of California. Selenium isotope analyses of samples obtained from the Tulare Lake Drainage District flow-through wetland reveal small isotopic contrasts (mean difference 0.7%o) between surface water and reduced Se species in the underlying sediments. Selenium in aquatic macrophytes was very similar isotopically to the NaOH and Na2SO3 sediment extracts designed to recover soluble organic Se and Se(O), respectively. For the integrated on-farm drainage management sites, evaporite salts were slightly (approximately 0.6%o) enriched in the heavier isotope relative to the inferred parent waters, whereas surface soils were slightly (approximately 1.4%o) depleted. Bacterial or chemical reduction of Se(VI) or Se(IV) may be occurring at these sites, but the small isotopic contrasts suggest that other, less isotopically fractionating mechanisms are responsible for accumulation of reduced forms in the sediments. These findings provide evidence that Se assimilation by plants and algae followed by deposition and mineralization is the dominant transformation pathway responsible for accumulation of reduced forms of Se in the wetland sediments.

Herbel, M. J.; Johnson, T. M.; Tanji, K. K.; Gao, S.; Bullen, T. D.

2002-01-01

155

Calibration of a monochromator/spectrometer system for the measurement of photoelectron angular distributions and branching ratios  

SciTech Connect

We describe the techniques used in calibrating a monochromator/spectrometer system for gas-phase photoelectron angular distribution and branching ratio measurements. We report a self-consistent set of values for the Ne 2p, Ar 3p, Kr 4p/sub 3/2/ and 4p/sub 1/2/, and Xe 5p/sub 3/2/ and 5p/sub 1/2/ photoelectron asymmetry parameters and for the Kr 4p/sub 3/2/:4p/sub 1/2/ and Xe 5p/sub 3/2/:5p/sub 1/2/ branching ratios for the energy regions from threshold to approximately 15 iV. 22 refs., 7 figs.

Southworth, S.H.; Parr, A.C.; Hardis, J.E.; Dehmer, J.L.; Holland, D.M.P.

1985-01-01

156

Self-organised spatial patterns and chaos in a ratio-dependent predator–prey system  

Microsoft Academic Search

Mechanisms and scenarios of pattern formation in predator–prey systems have been a focus of many studies recently as they\\u000a are thought to mimic the processes of ecological patterning in real-world ecosystems. Considerable work has been done with\\u000a regards to both Turing and non-Turing patterns where the latter often appears to be chaotic. In particular, spatiotemporal\\u000a chaos remains a controversial issue

Malay Banerjee; Sergei Petrovskii

2011-01-01

157

Simulating Complex Dynamics In Intermediate And Large-Aspect-Ratio Convection Systems  

Microsoft Academic Search

Buoyancy-induced (Rayleigh-Benard) convection of a fluid between two\\u000ahorizontal plates is a central paradigm for studying the transition to complex\\u000aspatiotemporal dynamics in sustained nonequilibrium systems. To improve the\\u000aanalysis of experimental data and the quantitative comparison of theory with\\u000aexperiment, we have developed a three-dimensional finite-difference code that\\u000acan integrate the three-dimensional Boussinesq equations (which govern the\\u000aevolution of

Ming-Chih Lai; Keng-Hwee Chiam; M. C. Cross; Henry Greenside

2000-01-01

158

Compact point-detection fluorescence spectroscopy system for quantifying intrinsic fluorescence redox ratio in brain cancer diagnostics  

PubMed Central

We report the development of a compact point-detection fluorescence spectroscopy system and two data analysis methods to quantify the intrinsic fluorescence redox ratio and diagnose brain cancer in an orthotopic brain tumor rat model. Our system employs one compact cw diode laser (407 nm) to excite two primary endogenous fluorophores, reduced nicotinamide adenine dinucleotide, and flavin adenine dinucleotide. The spectra were first analyzed using a spectral filtering modulation method developed previously to derive the intrinsic fluorescence redox ratio, which has the advantages of insensitivty to optical coupling and rapid data acquisition and analysis. This method represents a convenient and rapid alternative for achieving intrinsic fluorescence-based redox measurements as compared to those complicated model-based methods. It is worth noting that the method can also extract total hemoglobin concentration at the same time but only if the emission path length of fluorescence light, which depends on the illumination and collection geometry of the optical probe, is long enough so that the effect of absorption on fluorescence intensity due to hemoglobin is significant. Then a multivariate method was used to statistically classify normal tissues and tumors. Although the first method offers quantitative tissue metabolism information, the second method provides high overall classification accuracy. The two methods provide complementary capabilities for understanding cancer development and noninvasively diagnosing brain cancer. The results of our study suggest that this portable system can be potentially used to demarcate the elusive boundary between a brain tumor and the surrounding normal tissue during surgical resection.

Liu, Quan; Grant, Gerald; Li, Jianjun; Zhang, Yan; Hu, Fangyao; Li, Shuqin; Wilson, Christy; Chen, Kui; Bigner, Darell; Vo-Dinh, Tuan

2011-01-01

159

A five-collector system for the simultaneous measurement of argon isotope ratios in a static mass spectrometer  

USGS Publications Warehouse

A system is described that utilizes five separate Faraday-cup collector assemblies, aligned along the focal plane of a mass spectrometer, to collect simultaneous argon ion beams at masses 36-40. Each collector has its own electrometer amplifier and analog-to-digital measuring channel, the outputs of which are processed by a minicomputer that also controls the mass spectrometer. The mass spectrometer utilizes a 90?? sector magnetic analyzer with a radius of 23 cm, in which some degree of z-direction focussing is provided for all the ion beams by the fringe field of the magnet. Simultaneous measurement of the ion beams helps to eliminate mass-spectrometer memory as a significant source of measurement error during an analysis. Isotope ratios stabilize between 7 and 9 s after sample admission into the spectrometer, and thereafter changes in the measured ratios are linear, typically to within ??0.02%. Thus the multi-collector arrangement permits very short extrapolation times for computation of initial ratios, and also provides the advantages of simultaneous measurement of the ion currents in that errors due to variations in ion beam intensity are minimized. A complete analysis takes less than 10 min, so that sample throughput can be greatly enhanced. In this instrument, the factor limiting analytical precision now lies in short-term apparent variations in the interchannel calibration factors. ?? 1981.

Stacey, J. S.; Sherrill, N. D.; Dalrymple, G. B.; Lanphere, M. A.; Carpenter, N. V.

1981-01-01

160

A Neuro-Fuzzy Inference System Combining Wavelet Denoising, Principal Component Analysis, and Sequential Probability Ratio Test for Sensor Monitoring  

SciTech Connect

A neuro-fuzzy inference system combined with the wavelet denoising, principal component analysis (PCA), and sequential probability ratio test (SPRT) methods has been developed to monitor the relevant sensor using the information of other sensors. The parameters of the neuro-fuzzy inference system that estimates the relevant sensor signal are optimized by a genetic algorithm and a least-squares algorithm. The wavelet denoising technique was applied to remove noise components in input signals into the neuro-fuzzy system. By reducing the dimension of an input space into the neuro-fuzzy system without losing a significant amount of information, the PCA was used to reduce the time necessary to train the neuro-fuzzy system, simplify the structure of the neuro-fuzzy inference system, and also, make easy the selection of the input signals into the neuro-fuzzy system. By using the residual signals between the estimated signals and the measured signals, the SPRT is applied to detect whether the sensors are degraded or not. The proposed sensor-monitoring algorithm was verified through applications to the pressurizer water level, the pressurizer pressure, and the hot-leg temperature sensors in pressurized water reactors.

Na, Man Gyun [Chosun University (Korea, Republic of); Oh, Seungrohk [Dankook University (Korea, Republic of)

2002-11-15

161

Development of Polymer Gel Systems to Improve Volumetric Sweep and Reduce Producing Water/Oil Ratios  

SciTech Connect

Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of a 42-month research program that focused on the understanding of gelation chemistry and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work was conducted on a widely applied system in the field, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. Pre-gel aggregates form and grow as reactions between chromium acetate and polyacrylamide proceed. A rate equation that describes the reaction between chromium acetate and polymer molecules was regressed from experimental data. A mathematical model that describes the crosslinking reaction between two polymer molecules as a function of time was derived. The model was based on probability concepts and provides molecular-weight averages and molecular-weight distributions of the pre-gel aggregates as a function of time and initial system conditions. Average molecular weights of pre-gel aggregates were measured as a function of time and were comparable to model simulations. Experimental methods to determine molecular weight distributions of pre-gel aggregates were unsuccessful. Dissolution of carbonate minerals during the injection of gelants causes the pH of the gelant to increase. Chromium precipitates from solution at the higher pH values robbing the gelant of crosslinker. Experimental data on the transport of chromium acetate solutions through dolomite cores were obtained. A mathematical model that describes the transport of brine and chromium acetate solutions through rocks containing carbonate minerals was used to simulate the experimental results and data from literature. Gel treatments usually reduce the permeability to water to a greater extent than the permeability to oil is reduced. This phenomenon is referred to as disproportionate permeability reduction (DPR). Flow experiments were conducted in sandpacks to determine the effect of polymer and chromium concentrations on DPR. All gels studied reduced the permeability to water by a greater factor than the factor by which the oil permeability was reduced. Greater DPR was observed as the concentrations of polymer and chromium were increased. A conceptual model of the mechanisms responsible for DPR is presented. Primary features of the model are (1) the development of flow channels through the gel by dehydration and displacement of the gel and by re-connection of pre-treatment, residual oil volume and (2) high flow resistance in the channels during water flow is caused by significant saturations of oil remaining in the channels. A similar study of DPR was conducted in Berea sandstone cores. Both oil and water permeabilities were reduced by much smaller factors in Berea sandstone cores than in similar treatments in sandpacks. Poor maturation of the gelant in the Berea rock was thought to be caused by fluid-rock interactions that interfered with the gelation process.

G. Paul Willhite; Stan McCool; Don W. Green; Min Cheng; Feiyan Chen

2005-12-31

162

Predicting prey population dynamics from kill rate, predation rate and predator-prey ratios in three wolf-ungulate systems.  

PubMed

1.?Predation rate (PR) and kill rate are both fundamental statistics for understanding predation. However, relatively little is known about how these statistics relate to one another and how they relate to prey population dynamics. We assess these relationships across three systems where wolf-prey dynamics have been observed for 41 years (Isle Royale), 19 years (Banff) and 12 years (Yellowstone). 2.?To provide context for this empirical assessment, we developed theoretical predictions of the relationship between kill rate and PR under a broad range of predator-prey models including predator-dependent, ratio-dependent and Lotka-Volterra dynamics. 3.?The theoretical predictions indicate that kill rate can be related to PR in a variety of diverse ways (e.g. positive, negative, unrelated) that depend on the nature of predator-prey dynamics (e.g. structure of the functional response). These simulations also suggested that the ratio of predator-to-prey is a good predictor of prey growth rate. That result motivated us to assess the empirical relationship between the ratio and prey growth rate for each of the three study sites. 4.?The empirical relationships indicate that PR is not well predicted by kill rate, but is better predicted by the ratio of predator-to-prey. Kill rate is also a poor predictor of prey growth rate. However, PR and ratio of predator-to-prey each explained significant portions of variation in prey growth rate for two of the three study sites. 5.?Our analyses offer two general insights. First, Isle Royale, Banff and Yellowstone are similar insomuch as they all include wolves preying on large ungulates. However, they also differ in species diversity of predator and prey communities, exploitation by humans and the role of dispersal. Even with the benefit of our analysis, it remains difficult to judge whether to be more impressed by the similarities or differences. This difficulty nicely illustrates a fundamental property of ecological communities. Second, kill rate is the primary statistic for many traditional models of predation. However, our work suggests that kill rate and PR are similarly important for understanding why predation is such a complex process. PMID:21569029

Vucetich, John A; Hebblewhite, Mark; Smith, Douglas W; Peterson, Rolf O

2011-05-13

163

HIGH FILL-OUT, EXTREME MASS RATIO OVERCONTACT BINARY SYSTEMS. X. THE NEWLY DISCOVERED BINARY XY LEONIS MINORIS  

SciTech Connect

The newly discovered short-period close binary star, XY LMi, has been monitored photometrically since 2006. Its light curves are typical EW-type light curves and show complete eclipses with durations of about 80 minutes. Photometric solutions were determined through an analysis of the complete B, V, R, and I light curves using the 2003 version of the Wilson-Devinney code. XY LMi is a high fill-out, extreme mass ratio overcontact binary system with a mass ratio of q = 0.148 and a fill-out factor of f = 74.1%, suggesting that it is in the late evolutionary stage of late-type tidal-locked binary stars. As observed in other overcontact binary stars, evidence for the presence of two dark spots on both components is given. Based on our 19 epochs of eclipse times, we found that the orbital period of the overcontact binary is decreasing continuously at a rate of dP/dt = -1.67 x 10{sup -7} days yr{sup -1}, which may be caused by mass transfer from the primary to the secondary and/or angular momentum loss via magnetic stellar wind. The decrease of the orbital period may result in the increase of the fill-out, and finally, it will evolve into a single rapid-rotation star when the fluid surface reaches the outer critical Roche lobe.

Qian, S.-B.; Liu, L.; Zhu, L.-Y.; He, J.-J. [National Astronomical Observatories/Yunnan Astronomical Observatory, Chinese Academy of Sciences (CAS), P.O. Box 110, 650011 Kunming (China); Yang, Y.-G. [School of Physics and Electric Information, Huaibei Coal Industry Teachers College, 235000 Huaibei, Anhui Province (China); Bernasconi, L., E-mail: qsb@ynao.ac.cn, E-mail: yygcn@163.com, E-mail: laurent.bernasconi.51@wanadoo.fr [Les Engarouines Observatory, F-84570 Malemort-du-Comtat (France)

2011-05-15

164

Note: A signal-to-noise ratio enhancement based on wafer light irradiation system for optical modulation spectroscopy measurement  

NASA Astrophysics Data System (ADS)

We have recently found that the magnitude of the photoreflectance (PR) signal ?R/R on silicon wafers depends on the duration of continuous probe or pump beams irradiation. This temporal behavior of the ?R/R signal is attributed to the defects related electronic states at the Si/ SiO2 interface, which could be modified by the optical irradiation. Prior to the actual measurement, an optical irradiation of the silicon on insulator or ion implanted Si wafer can significantly enhance the signal-to-noise ratio of the PR intensity and, therefore, improve the goodness of fit. Such phenomena can be exclusively seen using a rapid detection system. A new design of the method is reported.

Chouaib, H.; Kelly, P. V.

2012-02-01

165

Peak-to-Average-Power-Ratio (PAPR) reduction in WiMAX and OFDM/A systems  

NASA Astrophysics Data System (ADS)

A peak to average power ratio (PAPR) reduction method is proposed that exploits the precoding or beamforming mode in WiMAX. The method is applicable to any OFDM/A systems that implements beamforming using dedicated pilots which use the same beamforming antenna weights for both pilots and data. Beamforming performance depends on the relative phase shift between antennas, but is unaffected by a phase shift common to all antennas. PAPR, on the other hand, changes with a common phase shift and this paper exploits that property. An effective optimization technique based on sequential quadratic programming is proposed to compute the common phase shift. The proposed technique has several advantages compared with traditional PAPR reduction techniques in that it does not require any side-information and has no effect on power and bit-error-rate while providing better PAPR reduction performance than most other methods.

Khademi, Seyran; Svantesson, Thomas; Viberg, Mats; Eriksson, Thomas

2011-12-01

166

Deep, Low Mass Ratio Overcontact Binary Systems. VI. AH Cancri in the Old Open Cluster M67  

NASA Astrophysics Data System (ADS)

CCD photometric light curves in the B and V bands obtained in 2001 and in the V band obtained in 2002 of AH Cnc in the old open cluster M67 are presented. It is shown that AH Cnc is a total-eclipsing binary and its light curves correspond to a typical A type according to Binnendijk's classification. The variations of the light curve around the primary minimum and second maximum were found. Our nine epochs of light minimum monitored from 2001 to 2005, including others collected from the literature, were used to create the first study of the period changes of the binary system. A cyclic oscillation with a period of 36.5 yr and an amplitude of 0.0237 days was discovered to be superposed on a continuous period increase (dP/dt=3.99×10-7 days yr-1). Weak evidence indicates that there exists another small-amplitude period oscillation (A4=0.0035 days, P4=7.75 yr). The symmetric light curves in the B and V bands obtained in 2001 were analyzed with the 2003 version of the Wilson-Devinney code. It is confirmed that AH Cnc is a deep overcontact binary system with a high degree of overcontact f=58.5%+/-4.5% and a low mass ratio of q=0.1682+/-0.0012. The existence of the third light and the cyclic period oscillation both may suggest that AH Cnc is a triple system containing an unseen third body. The tertiary component may have played an important role in the origin of the overcontact binary star by removing angular momentum from the central system, which would cause it to have a short initial orbital period and thus evolve into an overcontact configuration by angular momentum loss. The long-term period increase can be interpreted as a mass transfer from the less massive component to the more massive one. As the orbital period increases, the decrease of the mass ratio will cause it finally to evolve into a single rapid-rotating star when the system meets the more familiar criterion that the orbital angular momentum be less than 3 times the total spin angular momentum. Therefore, AH Cnc may be a progenitor of the blue straggler stars in M67.

Qian, S.-B.; Liu, L.; Soonthornthum, B.; Zhu, L.-Y.; He, J.-J.

2006-06-01

167

Phase ratios in the M 2 O-V 2 O 5 SO 3 (M = Rb, Cs) systems and the properties of the compounds formed in these systems  

Microsoft Academic Search

Powder X-ray diffraction and microscopy have been used to study phase ratios of the M2O-V2O5-SO3 (M = Rb, Cs) systems, which model the active component of rubidium-vanadium and cesium-vanadium catalysts for sulfuric acid\\u000a production at high sulfur dioxide conversions. We have stated that each system forms four compounds: M3VO2(SO4)2, MVO2SO4, M4V2O3(SO4)4, and MVO(SO4)2. The thermal properties of these compounds and

V. N. Krasil’nikov

2007-01-01

168

Impact of heel effect and ROI size on the determination of contrast-to-noise ratio for digital mammography systems  

NASA Astrophysics Data System (ADS)

The European Guidelines for quality control in digital mammography specify a procedure for measuring contrast-to-noise ratio (CNR) using a 0.2mm thickness of aluminium with different thicknesses of Plexiglas. The relationship between ROI size and heel effect and how this affects CNR measurement is investigated in this work for DR and CR systems. The measured relative noise for the CR images was found to be strongly dependant on the ROI size due to the heel effect. After applying heel effect correction there was very little dependence on ROI size. The relative noise in the images from the DR system showed very little dependence on ROI size. The heel effect also distorted the CNR measurement on CR images when larger ROI is used. However the use of multiple small ROIs led to a result that was essentially the same as if a heel effect correction had been applied. The appropriate ROI size which should be used for CNR measurement was found to be 0.25 × 0.25 cm. Using this size the heel effect had an insignificant impact on the measurement of relative noise and CNR. This approach has the advantage that only a single image is required for each measurement. The application of heel effect correction with CR systems requires two images and complex image processing. The current suggestion in the European guidelines to use a 2 × 2cm ROI is inappropriate for CR systems and leads to an error of 8% to 18% in CNR determination due to the heel effect.

Alsager, Abdulaziz; Young, Kenneth C.; Oduko, Jennifer M.

2008-04-01

169

Deep, Low Mass Ratio Overcontact Binary Systems. VII. QX Andromedae in the Intermediate-Age Open Cluster NGC 752  

NASA Astrophysics Data System (ADS)

QX Andromedae is a short-period eclipsing binary in the intermediate-age open cluster NGC 752. Charge-coupled device photometric observations of the close binary system obtained from 2004 November 13 to 2006 November 18 are presented. It is confirmed that the light curves show partial eclipses, and night-to-night intrinsic variations are seen. As in the case of AH Cancri in the old open cluster M67, the light curve of QX And seems to change between A and W types. Both the short- and long-term light variations suggest that QX And shows strong magnetic activity, which is in agreement with its X-ray observations. The symmetric light curves in B and V bands obtained the night of 2004 November 13 were analyzed with the new version of the W-D code. It is found that QX And is a deep overcontact binary system with a high degree of overcontact of f = 55.9% and a low mass ratio of q = 0.2327, suggesting that it is in the late stage of overcontact evolution. Based on our 23 times of light minimum, including four recently published eclipse times, the orbital period of the eclipsing binary was revised. It was discovered that the orbital period shows a continuous period increase at a rate of dP/dt = +2.48 × 10-7 days yr-1, which can be interpreted as a mass transfer from the less massive component to the more massive one. As the period increases, the mass ratio of the system will decrease. It may finally evolve into a rapid-rotating single star when it meets the more familiar criterion that the orbital angular momentum is less than 3 times the total spin angular momentum. The existence of QX And in the late evolutionary stage of an overcontact binary in the intermediate-age open cluster NGC 752 indicates that it may undergo strong cluster stellar interaction. This means it had a very short initial orbital period and could have evolved into the present evolutionary state within the cluster age. By comparing with the evolutionary state of TX Cnc in M44, it is estimated that the lifetime of overcontact binaries may be no less than 1 Gyr.

Qian, S.-B.; Liu, L.; Soonthornthum, B.; Zhu, L.-Y.; He, J.-J.

2007-10-01

170

Deep, Low-mass Ratio Overcontact Binary Systems. XII. CK Bootis with Possible Cyclic Magnetic Activity and Additional Companion  

NASA Astrophysics Data System (ADS)

We present precision CCD photometry, a period study, and a two-color simultaneous Wilson code solution of the short-period contact binary CK Bootis. The asymmetric light curves were modeled by a dark spot on the primary component. The result identifies that CK Boo is an A-type W UMa binary with a high fillout of f = 71.7(± 4.4)%. From the O - C curve, it is found that the orbital period changes in a complicated mode, i.e., a long-term increase with two sinusoidal variations. One cyclic oscillation with a period of 10.67(± 0.20) yr may result from magnetic activity cycles, which are identified by the variability of Max. I - Max. II. Another sinusoidal variation (i.e., A = 0.0131 days(± 0.0009 days) and P 3 = 24.16(± 0.64) yr) may be attributed to the light-time effect due to a third body. This kind of additional companion can extract angular momentum from the central binary system. The orbital period secularly increases at a rate of dP/dt = +9.79 (±0.80) × 10-8 days yr-1, which may be interpreted by conservative mass transfer from the secondary to the primary. This kind of deep, low-mass ratio overcontact binaries may evolve into a rapid-rotating single star, only if the contact configuration do not break down at J spin > (1/3)J orb.

Yang, Y.-G.; Qian, S.-B.; Soonthornthum, B.

2012-05-01

171

Nurse staff allocation by nurse patient ratio vs. a computerized nurse dependency management system: a comparative cost analysis of Australian and New Zealand hospitals.  

PubMed

Coding, costing, and accounting for nursing care requirements in Australian public and private hospitals lacks systematic research. Nurse costing for two nurse staffing allocation methods--nurse patient ratios and a computerized nurse dependency management system--were compared. Retrospective nursing workload management data were obtained from hospital information systems in 21 acute care public and private hospitals in Australia and New Zealand. Descriptive statistics, cost analysis, and cost modeling were conducted for 103,269 shifts of nursing care. The comparison of costs for nursing staff by nurse-patient ratios and by a computerized nurse dependency management system demonstrated differences. The provision of nursing care using the computerized nurse dependency management system was, overall, lower in cost than for nurse-patient ratios. PMID:23346733

Heslop, Liza; Plummer, Virginia

172

The CO A-X System for Constraining Cosmological Drift of the Proton-Electron Mass Ratio  

NASA Astrophysics Data System (ADS)

The {A}^1?-{X}^1?^+ band system of carbon monoxide, which has been detected in six highly redshifted galaxies (z=1.6-2.7), is identified as a novel probe method to search for possible variations of the proton-electron mass ratio (?) on cosmological time scales. Laboratory wavelengths of the spectral lines of the A-X (v,0) bands for v=0-9 have been determined at an accuracy of ??/?=1.5 × 10^{-7} through VUV Fourier-transform absorption spectroscopy, providing a comprehensive and accurate zero-redshift data set. Two-photon Doppler-free laser spectroscopy has been applied for the (0,0) and (1,0) bands, achieving 3 × 10^{-8} accuracy level, verifying the absorption data. Accurate sensitivity coefficients K_{?} for a varying ? have been calculated for the CO A-X bands, so that an operational method results to search for ?-variation. The data from both experiments were used to perform an improved analysis of the perturbations in the A^1?, v=0 and 1 levels by vibrational levels in the D^1?, I^1?^-, e^3?^-, d^3?, and a'^3?^+ states. The object Q1237+064 will be observed in May 2013, aiming for a good signal-to-noise spectrum containing the CO A-X bands as well as the H_2 Lyman and Werner bands. This should result in an accurate and robust constraint on ??/?. E.J. Salumbides, M.L. Niu, J. Bagdonaite, N. de Oliveira, D. Joyeux, L. Nahon and W. Ubachs, Phys. Rev. A 86, 022510 (2012).}

Niu, M. L.; Salumbides, E. J.; Zhao, D.; Bagdonaite, J.; De Oliveira, N.; Joyeux, D.; Nahon, L.; Field, R. W.; Ubachs, W.

2013-06-01

173

System-size dependence of particle-ratio fluctuations in Pb + Pb collisions at 158A GeV  

NASA Astrophysics Data System (ADS)

New measurements by the NA49 experiment of the centrality dependence of event-by-event fluctuations of the particle yield ratios (K++K-)/(?++?-), (p+p¯)/(?++?-), and (K++K-)/(p+p¯) are presented for Pb+Pb collisions at 158A GeV. The absolute values of the dynamical fluctuations of these ratios, quantified by the measure ?dyn, increase by about a factor of two from central to semiperipheral collisions. Multiplicity scaling scenarios are tested and found to apply for both the centrality and the previously published energy dependence of the (K++K-)/(?++?-) and (p+p¯)/(?++?-) ratio fluctuations. A description of the centrality and energy dependence of (K++K-)/(p+p¯) ratio fluctuations by a common scaling prescription is not possible since there is a sign change in the energy dependence.

Anticic, T.; Baatar, B.; Barna, D.; Bartke, J.; Beck, H.; Betev, L.; Bia?kowska, H.; Blume, C.; Bogusz, M.; Boimska, B.; Book, J.; Botje, M.; Bun?i?, P.; Cetner, T.; Christakoglou, P.; Chung, P.; Chvála, O.; Cramer, J. G.; Eckardt, V.; Fodor, Z.; Foka, P.; Friese, V.; Ga?dzicki, M.; Grebieszkow, K.; Höhne, C.; Kadija, K.; Karev, A.; Kolesnikov, V. I.; Kollegger, T.; Kowalski, M.; Kresan, D.; László, A.; Lacey, R.; van Leeuwen, M.; Ma?kowiak-Paw?owska, M.; Makariev, M.; Malakhov, A. I.; Mateev, M.; Melkumov, G. L.; Mitrovski, M.; Mrówczy?ski, St.; Nicolic, V.; Pálla, G.; Panagiotou, A. D.; Peryt, W.; Pluta, J.; Prindle, D.; Pühlhofer, F.; Renfordt, R.; Roland, C.; Roland, G.; Rybczy?ski, M.; Rybicki, A.; Sandoval, A.; Schmitz, N.; Schuster, T.; Seyboth, P.; Siklér, F.; Skrzypczak, E.; S?odkowski, M.; Stefanek, G.; Stock, R.; Ströbele, H.; Susa, T.; Szuba, M.; Utvi?, M.; Varga, D.; Vassiliou, M.; Veres, G. I.; Vesztergombi, G.; Vrani?, D.; W?odarczyk, Z.; Wojtaszek-Szwarc, A.

2013-02-01

174

[Film quality in film mammography. Article II: Signal/noise ratio of the recording system as a quantitative measure of quality. Final evaluation of recording systems (author's transl)].  

PubMed

During consideration of three film mammographic systems (see article I), the concept of signal/noise ratio is developed as a quantitative measure of film quality. The ability to recognise detail related to detail size, film blackening and exposure geometry was studied for various systems, and the quality profiles are discussed. There is a considerable difference in quality between industrial films without screens and film-screen combinations; however, exposure geometry during mammography has a considerable effect which tends to reduce the difference. Consequently, detail sizes of 200 mu to 1,000 mu (including the majority of mammographic micro-calcifications) are shown about equally well. Contrast for the lo-dose system (D = 1.1) is somewhat less than for adequately exposed industrial film (D = 2.0) or for Cronex 75 m with lo-dose screen (D = 1.5 to 2.0). The lo-dose system (D = 1.1) is 8.6 times more sensitive than Cronex 75 m (D = 2.0), and the system Cronex 75 m with lo-dose screens is 11.6 times more sensitive. Over-exposure with the lo-dose system, contrary to industrial film, rapidly leads to unsatisfactory results (loss of contrast and increased granularity for D greater than 1.5). On the other hand it is often not possible to obtain an adequate exposure (D = 2.0) when using industrial film. For these reasons it is often an advantage to examine large breasts (with considerable geometric unsharpness) and the dense breasts of young women with a film-screen combination (eg. lo-dose system) which requires approximately one eighth of the dose necessary for industrial film. For small or easily compressable breasts (little geometric unsharpness) best results are obtained, using an adequate exposure by employing industrial film; radiation dose it then acceptable. Detailed analysis of the systems has shown that the recording system unsharpness of film-screen combinations in mammography should be reduced. PMID:137194

Friedrich, M; Weskamp, P

1976-11-01

175

Neutral beam interlock system on TFTR using infrared pyrometry  

SciTech Connect

Although the region of the TFTR vacuum vessel wall which is susceptible to damage by neutral beam strike is armored with a mosaic of TiC-clad POCO graphite titles, at power deposition levels above 2.5 kW/cm/sup 2/ the armor surface temperature exceeds 1200/sup 0/C within 250 ms and itself becomes susceptible to damage. In order to protect the wall armor, a neutral beam interlock system based on infrared pyrometry measurement of the armor surface temperature was installed on TFTR. For each beamline, a three-fiber-optic telescope views three areas of approx.30 cm diameter centered on the armor hot spots for the three ion sources. Each signal is fiber-optic coupled to a remote 900 nm pyrometer which feeds analog signals to the neutral beam interrupt circuits. The pyrometer interlock system is designed to interrupt each of the twelve ion sources independently within 10 ms of the temperature exceeding a threshold settable in the range of 500 to 2300/sup 0/C. A description of the pyrometer interlock system and its performance will be presented.

Medley, S.S.; Kugel, H.W.; Kozub, T.A.; Lowrance, J.L.; Mastrocola, V.; Renda, G.; Young, K.M.

1986-06-01

176

Your fate is in your hands? Handedness, digit ratio (2D:4D), and selection to a national talent development system.  

PubMed

Over the past decade a small evidence base has highlighted the potential importance of seemingly innocuous variables related to one's hands, such as hand dominance and the relative length of the second and fourth digits (2D:4D ratio), to success in sport. This study compared 2D:4D digit ratio and handedness among handball players selected to advance in a national talent development system with those not selected. Participants included 480 youth handball players (240 females and 240 males) being considered as part of the talent selection programme for the German Youth National team. Hand dominance and digit ratio were compared to age-matched control data using standard t-tests. There was a greater proportion of left-handers compared to the normal population in males but not in females. There was also a lower digit ratio in both females and males. However, there were no differences between those selected for the next stage of talent development and those not selected on either handedness or digit ratio. These results add support for general effects for both digit ratio and handedness in elite handball; however, these factors seem inadequate to explain talent selection decisions at this level. PMID:23444944

Baker, Joseph; Kungl, Ann-Marie; Pabst, Jan; Strauß, Bernd; Büsch, Dirk; Schorer, Jörg

2013-02-28

177

Low-Speed Aerodynamic Characteristics of a Rectangular, Aspect-Ratio-6, Slotted Supercritical Airfoil Wing Having Several High-Lift Flap Systems.  

National Technical Information Service (NTIS)

Tests were conducted in the Langley high-speed 7- by 10-foot tunnel on a rectangular aspect-ratio-6 wing which had a supercritical airfoil section. The wing was fitted with several high-lift flap systems: plain flap, single-slotted flap, and a double-slot...

K. W. Goodson

1971-01-01

178

Measurements of concentrations of chlorofluoromethanes (CFMs) carbon dioxide and carbon isotope ratio in stratospheric and tropospheric air by grab-sampling systems  

Microsoft Academic Search

Measurements of concentrations of chlorofluoromethanes (CFMs), carbon dioxide and carbon isotope ratio in stratospheric and tropospheric air by grab-sampling systems are reported. The balloon-borne grab-sampling system has been launched from Sanriku Balloon Center three times since 1981. It consists of: (1) six sampling cylinders, (2) eight motor driven values, (3) control and monitor circuits, and (4) pressurized housing. Particular consideration

T. Itoh; H. Kubo; H. Honda; T. Tominaga; Y. Makide; A. Yakohata; H. Sakai

1985-01-01

179

40 CFR 141.534 - How does my system use this data to calculate an inactivation ratio?  

Code of Federal Regulations, 2013 CFR

...Filtration and Disinfection-Systems Serving Fewer Than 10,000... § 141.534 How does my system use this data to calculate...value by 3.0 to determine log inactivation of Giardia lamblia: If your system * * * Your system must...

2013-07-01

180

Short communication Technique to measure CO2 mixing ratio in small flasks with a bellows\\/IRGA system  

Microsoft Academic Search

We developed a laboratory method to obtain high precision CO2 mixing ratios in air samples contained in 100 ml glass flasks, which involves extracting air from the flask into a pre-evacuated manifold containing a variable-volume metal bellows. Compressed air from the bellows is then routed to a non-dispersive infrared gas analyzer (IRGA). Tests indicate that this configuration has an overall

D. R. Bowling; C. S. Cook; J. R. Ehleringer

2001-01-01

181

How large can the electron to proton mass ratio be in particle-in-cell simulations of unstable systems?  

SciTech Connect

Particle-in-cell simulations are widely used as a tool to investigate instabilities that develop between a collisionless plasma and beams of charged particles. However, even on contemporary supercomputers, it is not always possible to resolve the ion dynamics in more than one spatial dimension with such simulations. The ion mass is thus reduced below 1836 electron masses, which can affect the plasma dynamics during the initial exponential growth phase of the instability and during the subsequent nonlinear saturation. The goal of this article is to assess how far the electron to ion mass ratio can be increased, without changing qualitatively the physics. It is first demonstrated that there can be no exact similarity law, which balances a change in the mass ratio with that of another plasma parameter, leaving the physics unchanged. Restricting then the analysis to the linear phase, a criterion allowing to define a maximum ratio is explicated in terms of the hierarchy of the linear unstable modes. The criterion is applied to the case of a relativistic electron beam crossing an unmagnetized electron-ion plasma.

Bret, A. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real (Spain) and Instituto de Investigaciones Energeticas y Aplicaciones Industriales, 13071 Ciudad Real (Spain); Dieckmann, M. E. [Department of Science and Technology (ITN), VITA, Linkoeping University, 60174 Norrkoeping (Sweden)

2010-03-15

182

New measurement method of Poisson's ratio of PVA hydrogels using an optical flow analysis for a digital imaging system  

NASA Astrophysics Data System (ADS)

In this paper, we propose a method to observe deformation, to measure strain and to calculate Poisson's ratio of a soft material such as a polyvinyl alcohol hydrogel by means of an optical flow analysis during a tensile test. Compared to the conventional digital image correlation method of which the basic assumption is that the local target region in an image is under linear deformation, an optical flow method can measure local deformation up to the pixel level of the image. In addition, sub-pixel measurements are possible by means of bi-cubic interpolation of each flow vector. To guarantee the accuracy of the optical flow vectors, the scale-invariant feature transform was used. Random sample consensus (RANSAC) for eliminating noisy features and then obtaining a more accurate result was applied. The mean value of Poisson's ratio is 0.4498 and the standard deviation comes to 0.0305. This optical flow method can also be applied to calculate Poisson's ratio of other soft materials.

Chen, Feifei; Kang, Dong-Joong; Park, Jun-Hyub

2013-05-01

183

Modeling the maintenance of a dependent lineage system: the influence of positive frequency-dependent selection on sex ratio.  

PubMed

In insect societies, worker versus queen development (reproductive caste) is typically governed by environmental factors, but some Pogonomyrmex seed-harvester ants exhibit strict genetic caste determination, resulting in an obligate mutualism between two reproductively isolated lineages. Queens mate randomly with multiple males from each lineage and intralineage crosses produce new queens, whereas interlineage crosses produce workers. Early colony survival is negatively frequency dependent; when lineage frequencies are unequal, queens from the rarer lineage benefit because they acquire more interlineage sperm, and produce more workers. Here we examine theoretically and empirically the effect of relative lineage frequency on sex ratio. We predict that the ratio of inter- to intralineage sperm acquired by queens of each lineage will affect the sex ratio produced at colony maturity. Consistent with model predictions, we found that gyne production in mature colonies was positively frequency dependent, increasing significantly with increasing lineage frequency across 15 populations. Unequal lineage frequencies are common and likely maintained by a complex interplay between an ecological advantage specific to one lineage, and opposing frequency-dependent selection pressures experienced throughout the colonies life-cycle; rare lineage colonies benefit during early colony growth, and common lineage colonies benefit at reproductive maturity. PMID:19453732

Anderson, Kirk E; Smith, Chris R; Linksvayer, Timothy A; Mott, Brendon M; Gadau, Jürgen; Fewell, Jennifer H

2009-03-27

184

A Dual-Mode Generalized Likelihood Ratio Approach to Self-Reorganizing Digital Flight Control System Design.  

National Technical Information Service (NTIS)

The research is reported on the problems of failure detection and reliable system design for digital aircraft control systems. Failure modes, cross detection probability, wrong time detection, application of performance tools, and the GLR computer package...

R. Bueno E. Chow S. B. Gershwin A. S. Willsky

1975-01-01

185

40 CFR 141.536 - My system has developed an inactivation ratio; what must we do now?  

Code of Federal Regulations, 2013 CFR

...Filtration and Disinfection-Systems Serving Fewer Than 10,000...Disinfection Profile § 141.536 My system has developed an inactivation...what must we do now? Each log inactivation serves as a data...disinfection profile. Your system will have obtained 52...

2013-07-01

186

Band Mechanism with Nonlinear Gear Ratio for Gravity Force Balance: Design and Analysis in Total System Network  

NASA Astrophysics Data System (ADS)

The application of band mechanisms offers a wide range of possibilities in designing concepts of modern guide mechanisms. The applied belt pulleys are designed as continuous convex cam disks and allow the application of different transmission functions. A large number of transmission functions can be generated with convex curve shapes. It takes a great deal of effort to determine the correct pulley curve and is difficult for engineers without special knowledge to calculate. The syntheses process of a nonlinear band mechanism is based on the relationships between the evolute and evolvente [1]. The evolute corresponds to the pulley curve and the evolvente corresponds, for example, to the curve of the fix point of a rocker arm. By applying this method in relation with the reverse kinematics and the maintenance of total band length, allowing to generate band mechanism with required curve of transmission ratio. Beside the comments of band mechanism construction and the mathematical method of resolution—the first part of the article explains a simple four bar mechanism of couch chest the total gravity force balance with band mechanism. Therefore, the essential computing steps and limits of the solving process will be explained. With this it is possible to calculate the nonlinear transmission ratio of band mechanism with consideration of elastic band properties and inertia of bodies.

Ebert, F.; Berger, M.

187

System and method to estimate compressional to shear velocity (VP/VS) ratio in a region remote from a borehole  

DOEpatents

In some aspects of the disclosure, a method for creating three-dimensional images of non-linear properties and the compressional to shear velocity ratio in a region remote from a borehole using a conveyed logging tool is disclosed. In some aspects, the method includes arranging a first source in the borehole and generating a steered beam of elastic energy at a first frequency; arranging a second source in the borehole and generating a steerable beam of elastic energy at a second frequency, such that the steerable beam at the first frequency and the steerable beam at the second frequency intercept at a location away from the borehole; receiving at the borehole by a sensor a third elastic wave, created by a three wave mixing process, with a frequency equal to a difference between the first and second frequencies and a direction of propagation towards the borehole; determining a location of a three wave mixing region based on the arrangement of the first and second sources and on properties of the third wave signal; and creating three-dimensional images of the non-linear properties using data recorded by repeating the generating, receiving and determining at a plurality of azimuths, inclinations and longitudinal locations within the borehole. The method is additionally used to generate three dimensional images of the ratio of compressional to shear acoustic velocity of the same volume surrounding the borehole.

Vu, Cung; Nihei, Kurt T; Schmitt, Denis P; Skelt, Christopher; Johnson, Paul A; Guyer, Robert; TenCate, James A; Le Bas, Pierre-Yves

2012-10-16

188

Size-dependent pollen:ovule ratios and the allometry of floral sex allocation in Clarkia (Onagraceae) taxa with contrasting mating systems.  

PubMed

Multiple field populations of two pairs of diploid sister taxa with contrasting mating systems in the genus Clarkia (Onagraceae) were surveyed to test predictions concerning the effects of resource status, estimated as plant size, on pollen and ovule production and on the pollen:ovule (P:O) ratio of flowers. Most theoretical models of size-dependent sex allocation predict that, in outcrossing populations, larger plants should allocate more resources to female function. Lower P:O ratios in larger plants compared to smaller plants have been interpreted as supporting this prediction. In contrast, we predicted that P:O ratio should not vary with plant size in predominantly selfing plants, in which each flower contributes to reproductive success equally through male and female function. We found that, in all four taxa, both ovule and pollen production per flower usually increased significantly with plant size and that the shape of this relationship was decelerating. However, ovule production either decelerated more rapidly than or at the same rate as pollen production with plant size. Consequently,the P:O ratio increased or had no relationship with plant size. This relationship was population-specific (not taxon-specific) and independent of the mating system. Possible explanations for the increasing maleness with plant size are discussed. PMID:21628249

Delesalle, Véronique A; Mazer, Susan J

2009-04-13

189

The salivary alpha amylase over cortisol ratio as a marker to assess dysregulations of the stress systems  

Microsoft Academic Search

Different factors have been associated with changes in the regulation of the two major stress response systems of the human body, the sympathetic nervous system (SNS) and the hypothalamic–pituitary–adrenal (HPA) axis. Changes in these systems have been associated with various (psycho)pathologies across adulthood, and are thus frequently assessed within the context of allostatic load. Early Life Adversity (ELA) has been

Nida Ali; Jens C. Pruessner

190

Platinum ratio search versus golden ratio search  

Microsoft Academic Search

In this simulation study, we examine the traditional golden ratio search in view of cost minimization and search risk, and propose an alternative search plan with what we call “platinum ratio”. The golden ratio search has been thought the best for unimodal optimization. However, our study shows that the golden ratio search is the best only in the sense of

Xia Pan

2008-01-01

191

Alkali injection system with controlled CO.sub.2 /O.sub.2 ratios for combustion of coal  

DOEpatents

A high temperature combustion process for an organic fuel containing sulfur n which the nitrogen of air is replaced by carbon dioxide for combination with oxygen with the ratio of CO.sub.2 /O.sub.2 being controlled to generate combustion temperatures above 2000 K. for a gas-gas reaction with SO.sub.2 and an alkali metal compound to produce a sulfate and in which a portion of the carbon-dioxide rich gas is recycled for mixing with oxygen and/or for injection as a cooling gas upstream from heating exchangers to limit fouling of the exchangers, with the remaining carbon-dioxide rich gas being available as a source of CO.sub.2 for oil recovery and other purposes.

Berry, Gregory F. (Naperville, IL)

1988-01-01

192

Two-stage soil infiltration treatment system for treating ammonium wastewaters of low COD/TN ratios.  

PubMed

Soil infiltration treatment (SIT) is ineffective to treat ammonium wastewaters of total nitrogen (TN) > 100 mg l(-1). This study applied a novel two-stage SIT process for effective TN removal from wastewaters of TN>100 mg l(-1) and of chemical oxygen demand (COD)/TN ratio of 3.2-8.6. The wastewater was first fed into the soil column (stage 1) at hydraulic loading rate (HLR) of 0.06 m(3) m(-2) d(-1) for COD removal and total phosphorus (TP) immobilization. Then the effluent from stage 1 was fed individually into four soil columns (stage 2) at 0.02 m(3) m(-2) d(-1) of HLR with different proportions of raw wastewater as additional carbon source. Over the one-year field test, balanced nitrification and denitrification in the two-stage SIT revealed excellent TN removal (>90%) from the tested wastewaters. PMID:23186658

Lei, Zhongfang; Wu, Ting; Zhang, Yi; Liu, Xiang; Wan, Chunli; Lee, Duu-Jong; Tay, Joo-Hwa

2012-11-02

193

Alkali injection system with controlled CO/sub 2//O/sub 2/ ratios for combustion of coal  

DOEpatents

A high temperature combustion process for an organic fuel containing sulfur in which the nitrogen of air is replaced by carbon dioxide for combination with oxygen with the ratio of CO/sub 2//O/sub 2/ being controlled to generate combustion temperatures above 2000/sup 0/K for a gas-gas reaction with SO/sub 2/ and an alkali metal compound to produce a sulfate and in which a portion of the carbon-dioxide rich gas is recycled for mixing with oxygen and/or for injection as a cooling gas upstream from heating exchangers to limit fouling of the exchangers, with the remaining carbon-dioxide rich gas being available as a source of CO/sub 2/ for oil recovery and other purposes. Several advantages are associated with the invention. First, by using a low CO/sub 2//O/sub 2/ ratio, higher flame temperatures can be achieved, thereby substantially promoting the gas-gas reaction between alkali atoms and sulfur gases. Second, by providing a means for injecting additional CO/sub 2/ at various locations removed from the combustion zone, the heat transfer rate and cooling of the alkali sulfates can be tightly controlled without suffering either the loss in efficiency inherent in conventional gas recycle techniques or the added cost associated with the larger mass throughput rate and heat transfer surface area. Third, there is the ability to use the concept in retrofit applications by tailoring the CO/sub 2/ quantity recycled to match the heat utilization performance previously achieved using air as the oxidizing medium. Fourth, a natural reduction in nitrous oxides is achieved by eliminating the reaction of oxygen with the nitrogen in the oxidizer.

Berry, G.F.

1986-11-21

194

The Activity of the Hypothalamic-Pituitary-Adrenal Axis and the Sympathetic Nervous System in Relation to Waist\\/Hip Circumference Ratio in Men  

Microsoft Academic Search

Objective: To investigate possible differences, between generally and abdominally obese men, in activity and regulation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system.Research Methods and Procedures: Fifty non-diabetic, middle-aged men were selected to obtain two groups with similar body mass index (BMI) but different waist\\/hip circumference ratio (WHR). Measurements were performed of the activity of the HPA axis

Thomas Ljung; Göran Holm; Peter Friberg; Björn Andersson; Bengt-Åke Bengtsson; Johan Svensson; Mary Dallman; Bruce McEwen; Per Björntorp

2000-01-01

195

The effect of [Fe 3+ ]\\/[Fe 2+ ] molar ratio and iron salts concentration on the properties of superparamagnetic iron oxide nanoparticles in the water\\/ethanol\\/toluene system  

Microsoft Academic Search

In this study, we developed a convenient one-pot method with sodium oleate as both the surfactant and precipitant to synthesize\\u000a pure magnetite nanoparticles in the water\\/ethanol\\/toluene system. The initial molar ratio of [Fe3+]\\/[Fe2+] and the concentration of iron salts were changed in order to systematically investigate their influences on the chemical\\u000a and physical properties of nanoparticles, such as the crystal

Wen JiangKui-Lin; Kui-Lin Lai; Hao Hu; Xiao-Bo Zeng; Fang Lan; Ke-Xia Liu; Yao Wu; Zhong-Wei Gu

196

High Resolution Imaging of the Anomalous Flux-Ratio Gravitational Lens System CLASS B2045+265: Dark Or Luminous Satellites?  

SciTech Connect

The existence of flux-ratio anomalies between fold and cusp images in galaxy-scale strong-lens systems has led to an interpretation based on the presence of a high mass-fraction of cold-dark-matter (CDM) substructures around galaxies, as predicted by numerical N-body simulations. These substructures can cause large perturbations of the image magnifications, leading to changes in the image flux ratios. The flux-ratio anomaly is particularly evident in the radio-loud quadruple gravitational lens system CLASS B2045+265. In this paper, new high-resolution radio, optical, and infrared imaging of B2045+265 is presented which sheds more light on this anomaly and its possible causes. First, deep Very Long Baseline Array observations show very compact images, possibly with a hint of a jet, but with no evidence for differential scattering or scatter broadening. Hence, the flux-ratio anomaly is unlikely to be caused by refractive scattering in either the Milky Way or the lens galaxy. Second, optical and infrared observations with the Hubble Space Telescope and through Adaptive-Optics imaging with the W. M. Keck Telescope, show a previously undiscovered object--interpreted as a (tidally disrupted) dwarf satellite based on its colors and slight extension--between the main lens galaxy and the three anomalous flux-ratio images. Third, color variations in the early-type lens galaxy indicate recent star-formation, possibly the result of secondary infall of gas-rich satellites. A population of young galaxies around the lens system could explain the previously discovered strong [O II] emission. However, spiral structure and/or normal star formation in the lens galaxy cannot be excluded. In light of these new data, we propose a lens model for the system, including the observed dwarf satellite, which reproduces all positional and flux-ratio constraints, without the need for additional CDM substructure. Although the model is peculiar in that the dwarf galaxy must be highly flattened, the model is very similar to recently proposed mass models based on high-order multipole expansions.

McKean, J.P.; Koopmans, L.V.E.; Flack, C.E.; Fassnacht, C.D.; Thompson, D.; Matthews, K.; Blandford, R.D.; Readhead, A.C.S.; Soifer, B.T.; /UC, Davis /Bonn, Max Planck Inst., Radioastron. /Kapteyn Astron. Inst., Groningen /Bemidji State U. /Caltech /KIPAC, Menlo Park /Cornell U., Astron. Dept.

2006-11-10

197

Hydrogen isotope abundances in the solar system. Part II. Meteorites with terrestrial-like D/H ratio  

SciTech Connect

Hydrogen isotopic compositions were determined by progressive pyrolysis in type 6 to type 3 ordinary chondrites. A marked decrease in the isotopic composition patterns was observed at intermediate temperatures (250-300/sup 0/C) and results from the pyrolysis of a D-depleted component. A deltaD value of -400 per thousand for this component can be inferred from a mathematical treatment of the H concentration release pattern. At higher temperatures (600 to 900/sup 0/C) the bimodal deltaD pattern was observed in Hedjaz (L3-L6) with negative deltaD values, suggesting the presence of a carbonaceous chondrite-like organic polymer in this meteorite. An internal correlation between the bulk isotopic composition of HT H/sub 2/ and the maximum measured D/H ratio is interpreted as the result of either the mixing of two components (Model 1), namely a D-depleted H at -400 per thousand and a D-rich H at +5000 per thousand, or a progressive isotopic fractionation of a D-depleted reservoir (Model 2). The first model implies that the two components were present in different proportions at the time of the formation of each meteorite, and that metamorphism has homogenized the two phases. The uniqueness of the two isotopic end-members for all meteorites is not demonstrated. The second model relates the isotopic fractionation of the D-rich phase to the degree of equilibration of chondrites. All the isotopic variations reported in this work for ordinary chondrites can be explained quantitatively by either one of these two models.

Robert, F.; Javoy, M.; Halbout, J.; Dimon, B.; Merlivat, L.

1987-07-01

198

Biodegradable in situ gelling delivery systems containing pilocarpine as new antiglaucoma formulations: effect of a mercaptoacetic acid/N-isopropylacrylamide molar ratio  

PubMed Central

Ocular drug delivery is one of the most commonly used treatment modalities in the management of glaucoma. We have recently proposed the use of gelatin and poly(N-isopropylacrylamide) (PNIPAAm) graft copolymers as biodegradable in situ forming delivery systems for the intracameral administration of antiglaucoma medications. In this study, we further investigated the influence of carrier characteristics on drug delivery performance. The carboxyl-terminated PNIPAAm samples with different molecular weights were synthesized by varying the molar ratio of mercaptoacetic acid (MAA)/N-isopropylacrylamide (NIPAAm) from 0.05 to 1.25, and were determined by end-group titration. The preparation of gelatin-g-PNIPAAm (GN) copolymers from these thermoresponsive polymers was achieved using carbodiimide chemistry. Our results showed that the carboxylic end-capped PNIPAAm of high molecular weight may lead to the lower thermal phase transition temperature and slower degradation rate of GN vehicles than its low molecular weight counterparts. With a decreasing MAA/NIPAAm molar ratio, the drug encapsulation efficiency of copolymers was increased due to fast temperature-triggered capture of pilocarpine nitrate. The degradation of the gelatin network could greatly affect the drug release profiles. All of the GN copolymeric carriers demonstrated good corneal endothelial cell and tissue compatibility. It is concluded that different types of GN-based delivery systems exhibit noticeably distinct intraocular pressure-lowering effect and miosis action, thereby reflecting the potential value of a MAA/NIPAAm molar ratio in the development of new antiglaucoma formulations.

Lai, Jui-Yang

2013-01-01

199

On power allocation strategies for maximum signal to noise and interference ratio in an OFDM-MIMO system  

Microsoft Academic Search

Orthogonal frequency division multiplexing (OFDM) has been recently established for several systems such as HiperLAN\\/2 and Digital video\\/audio broadcasting, due the easy implementation of the modulator\\/demodulator and the equalizer. Moreover, also increasing interest is currently being put on multiple-input multiple-output (MIMO) channels, based on the use of antenna arrays at both the transmitter and the receiver. Here, we propose two

Antonio Pascual-iserte; Ana I. Pérez-neira; Miguel Angel Lagunas

2004-01-01

200

Robust limit on a varying proton-to-electron mass ratio from a single H2 system  

NASA Astrophysics Data System (ADS)

Context. The variation of the dimensionless fundamental physical constant ? = mp/me can be checked through observation of Lyman and Werner lines of molecular hydrogen in the spectra of distant QSOs. Only few, at present four, systems have been used for the purpose providing different results between the different authors. Aims: Our intention is to asses the accuracy of the investigation concerning a possible variation of the fundamental physical constant ? = mp/me and to provide more robust results. The goal in mind is to resolve the current controversy on variation of ? and devise explanations for the different findings. Methods: The demand for precision requires a deep understanding of the errors involved. Self-consistency in data analysis and effective techniques to handle unknown systematic errors are essential. An analysis based on independent data sets of QSO 0347-383 is put forward and new approaches for some of the steps involved in the data analysis are introduced. In this work we analyse two independent sets of observations of the same absorption system and for the first time we apply corrections for the observed offsets between discrete spectra mainly caused by slit illumination effects. Results: Drawing on two independent observations of a single absorption system in QSO 0347-383 our detailed analysis yields ??/? = (15 ± (9stat + 6sys)) × 10-6 at zabs = 3.025. Based on the scatter of the measured redshifts and the corresponding low significance of the redshift-sensitivity correlation we estimate the limit of accuracy of ?? measurements to ~300 m s-1, consisting of roughly 180 m s-1 due to the uncertainty of the absorption line fit and about 120 m s-1 allocated to systematics. Conclusions: Current analyses tend to underestimate the impact of systematic errors. This work presents alternative approaches to handle systematics and introduces methods required for precision analysis of QSO spectra available in the near future.

Wendt, M.; Molaro, P.

2011-02-01

201

A Novel Method of Estimating the Signal-to-Interference Ratio for One-Cell-Frequency-Reuse OF/TDMA Systems  

NASA Astrophysics Data System (ADS)

In one-cell-frequency-reuse Orthogonal Frequency Division Multiple Access based Time Division Multiple Access (OF/TDMA) systems, communication is blocked by interference from adjacent cells. The most promising solution would be an adaptive modulation and coding scheme that is controlled by estimating the signal-to-interference ratio (SIR). However, there has so far been no way to accurately estimate the SIR using the spreading codes for OF/TDMA systems, because of the asynchronous fast Fourier transform (FFT). In this paper, we propose a novel SIR estimation method that uses a spread pulse-wave symbol and carrier interferometry. Moreover, to introduce multi-input multi-output systems, we modify the proposed method by allocating a different spreading code to each cell. Computer simulation confirmed that the SIR is estimated accurately even if the FFT is asynchronous. On cell boundaries, the average estimation errors that are a ratio between accurate and estimated propagation characteristics are less than 2dB.

Moriyama, Masafumi; Harada, Hiroshi; Sampei, Seiichi; Funada, Ryuhei

202

The Golden Ratio  

NSDL National Science Digital Library

Students learn about ratios, including the “Golden Ratio”, a ratio of length to width that can be found in art, architecture, and nature. Students examine different ratios to determine whether the Golden Ratio can be found in the human body.

Mathematics, Illuminations N.

2009-02-18

203

Improvements in Carrier-to-Noise-Ratio (CNR) of Lightwave Amplitude Modulated Vestigial-Sideband (AM-VSB) Transmission Systems by the Use of Optical Isolators  

NASA Astrophysics Data System (ADS)

In lightwave community antena television (CATV) systems as well as other optical fiber communication networks, a transmitted optical signal is known to be degraded by an intensity noise produced within the fiber due to the interference between the signal and doubly reflected light. We report on the improvements to the signal degradation due to the double Rayleigh backscattering by inserting optical isolators in the trunk lines of the systems. A carrier-to-noise ratio (CNR) has been calculated as a function of the number and the insertion loss of the isolators. The calculated results indicate that there is an optimum number of isolators, and if the insertion loss is less than 0.3 dB, the CNR degradation can be restored by more than 60%. To test the calculated results, we conducted experiments for the specific case of employing one isolator, and obtained good agreements between the two.

Takeo, Takashi; Kanie, Tomohiko; Satoh, Katsuhiro; Aoyama, Shigeyuki; Itoh, Haruhiko; Hattori, Hajime

1995-09-01

204

Extreme oxygen isotope ratios in the early solar system: a stellar encounter with the young Sun or irradiation in protosolar outflows?  

NASA Astrophysics Data System (ADS)

The oxygen isotopic mapping by ion microprobe of the deuterium-rich acid insoluble organic macromolecule extracted from the Murchison meteorite revealed the presence of micrometersized silica-rich grains having extreme 18O/16O and 17O/16O ratios ( ~ 10-1). Such extreme ratios have previously been reported only once : in CO2 from the circumstellar enveloppe of the binary post-AGB star HR4049 (Cami & Yamamura 2001). However, by contrast with typical presolar interstellar grains preserved in primitive meteorites, which show a compositional scatter attributed to multiple stellar sources, 36 grains accounting for 1 ppm of the total meteorite show a mixing between a single endmember source of heavy oxygen and solar or close-to-solar oxygen. Silicon isotopes in these grains do not show any deviation from solar. These extremely unusual compositions are not explained by conventional stellar nucleosynthesis models. Neither interactions with Galactic Cosmic Rays, nor isotope selective photochemistry due to CO self-shielding, nor non-mass-dependant fractionations during chemical reactions can explain the observed compositions. However we show that irradiation of a gas of solar composition by particles with characteristics of 3He-rich impulsive solar flares can produce these compositions provided a selective chemical trapping of the nuclear-induced oxygen exists.We therefore propose two explanations for these extremely unusual oxygen isotope ratios in micrometer-sized silica-rich grains from the Murchison carbonaceous chondrite. (1) The young Sun encountered an exotic evolved star comparable to HR4049. (2) These compositions were produced in the solar system itself during an active phase of the young Sun by high energy particle irradiation of the circumsolar gas followed by a chemical trapping of the anomaly and condensation of SiO2-rich grains. A possible locale for the condensation of these grains may be energetic, SiO-rich protosolar outflows.

Aleon, J.; Robert, F.; Duprat, J.; Derenne, S.

205

[Performance of nitrogen and phosphorus removal from municipal wastewater of different C/N ratios using intelligent controlled systems sequencing batch biofilm reactor ( SBBR)].  

PubMed

The laboratory-scale experiments were conducted to treat synthetic municipal wastewater at different C/N ratios, using a developed intelligent controller sequencing batch biofilm reactor (SBBR), which formed alternative aerobic-anoxic environment. The performance of nitrogen and phosphorus removal was investigated under different conditions (T = 25 degrees C +/- 1 degrees C, V(aeration) = 150 L/h, COD = 300 mg/L, TP = 5 mg/L, TN = 30 mg/L, t(operation) = 15 d; TN = 60 mg/L, t(operation) = 20 d; TN = 90 mg/L, t(operation) = 20 d). The average removal efficiency of COD reaches 85.2%, 91.1% and 97.7%, the average removal efficiency of TP achieves 94.1%, 95.9%, 96.7% ,the average removal efficiency of NH4(+) -N reaches 95.8%, 99.2%, 80.0%, and the average removal efficiency of TN are 90.7%, 81.1%, 58.3%, respectively. With the decrease of C/N ratios, the removal efficiency of N decreases significantly, while the removal efficiency of COD and TP increase slightly. In intelligent controlled SBBR, simultaneous nitrification and denitrification and shortened simultaneous nitrification and denitrification occur, meanwhile, the denitrification of the system strengthens with the increasing of C/N ratios. After the influent finished, intelligent controlled SBBR starts to operate in aerobic-anoxic environment. The efficiency of phosphorus removal is high, moreover, the theory of phosphorus removal is different from the conventional theory of release anaerobic and uptake aerobic phosphorus. PMID:21634171

Jin, Yun-Xiao; Feng, Chuan-Ping; Ding, Da-Hu; Hao, Chun-Bo; Song, Lin

2011-03-01

206

Detailed Characterization of 2D and 3D Scatter-to-Primary Ratios of Various Breast Geometries Using a Dedicated CT Mammotomography System  

PubMed Central

With a dedicated breast CT system using a quasi-monochromatic x-ray source and flat-panel digital detector, the 2D and 3D scatter to primary ratios (SPR) of various geometric phantoms having different densities were characterized in detail. Projections were acquired using geometric and anthropomorphic breast phantoms. Each phantom was filled with 700ml of 5 different water-methanol concentrations to simulate effective boundary densities of breast compositions from 100% glandular (1.0g/cm3) to 100% fat (0.79g/cm3). Projections were acquired with and without a beam stop array. For each projection, 2D scatter was determined by cubic spline interpolating the values behind the shadow of each beam stop through the object. Scatter-corrected projections were obtained by subtracting the scatter, and the 2D SPRs were obtained as a ratio of the scatter to scatter-corrected projections. Additionally the (un)corrected data were individually iteratively reconstructed. The (un)corrected 3D volumes were subsequently subtracted, and the 3D SPRs obtained from the ratio of the scatter volume-to-scatter-corrected (or primary) volume. Results show that the 2D SPR values peak in the center of the volumes, and were overall highest for the simulated 100% glandular composition. Consequently, scatter corrected reconstructions have visibly reduced cupping regardless of the phantom geometry, as well as more accurate linear attenuation coefficients. The corresponding 3D SPRs have increased central density, which reduces radially. Not surprisingly, for both 2D and 3D SPRs there was a dependency on both phantom geometry and object density on the measured SPR values, with geometry dominating for 3D SPRs. Overall, these results indicate the need for scatter correction given different geometries and breast densities that will be encountered with 3D cone beam breast CT.

Shah, Jainil; Pachon, Jan H.; Madhav, Priti; Tornai, Martin P.

2012-01-01

207

Elucidating microbial processes in nitrate- and sulfate-reducing systems using sulfur and oxygen isotope ratios: The example of oil reservoir souring control  

NASA Astrophysics Data System (ADS)

Sulfate-reducing bacteria (SRB) are ubiquitous in anoxic environments where they couple the oxidation of organic compounds to the production of hydrogen sulfide. This can be problematic for various industries including oil production where reservoir "souring" (the generation of H 2S) requires corrective actions. Nitrate or nitrite injection into sour oil fields can promote SRB control by stimulating organotrophic nitrate- or nitrite-reducing bacteria (O-NRB) that out-compete SRB for electron donors (biocompetitive exclusion), and/or by lithotrophic nitrate- or nitrite-reducing sulfide oxidizing bacteria (NR-SOB) that remove H 2S directly. Sulfur and oxygen isotope ratios of sulfide and sulfate were monitored in batch cultures and sulfidic bioreactors to evaluate mitigation of SRB activities by nitrate or nitrite injection. Sulfate reduction in batch cultures of Desulfovibrio sp. strain Lac15 indicated typical Rayleigh-type fractionation of sulfur isotopes during bacterial sulfate reduction (BSR) with lactate, whereas oxygen isotope ratios in unreacted sulfate remained constant. Sulfur isotope fractionation in batch cultures of the NR-SOB Thiomicrospira sp. strain CVO was minimal during the oxidation of sulfide to sulfate, which had ?18O SO4 values similar to that of the water-oxygen. Treating an up-flow bioreactor with increasing doses of nitrate to eliminate sulfide resulted in changes in sulfur isotope ratios of sulfate and sulfide but very little variation in oxygen isotope ratios of sulfate. These observations were similar to results obtained from SRB-only, but different from those of NR-SOB-only pure culture control experiments. This suggests that biocompetitive exclusion of SRB took place in the nitrate-injected bioreactor. In two replicate bioreactors treated with nitrite, less pronounced sulfur isotope fractionation and a slight decrease in ?18O SO4 were observed. This indicated that NR-SOB played a minor role during dosing with low nitrite and that biocompetitive exclusion was the major process. The results demonstrate that stable isotope data can contribute unique information for understanding complex microbial processes in nitrate- and sulfate-reducing systems, and offer important information for the management of H 2S problems in oil reservoirs and elsewhere.

Hubert, Casey; Voordouw, Gerrit; Mayer, Bernhard

2009-07-01

208

Concordance and population studies along with stutter and peak height ratio analysis for the PowerPlex ® ESX 17 and ESI 17 Systems.  

PubMed

The PowerPlex(®) ESX 17 and ESI 17 Systems for short tandem repeat (STR) amplification were developed by the Promega Corporation to meet the European Network of Forensic Science Institutes (ENFSI) and the European DNA Profiling (EDNAP) Group recommendations for increasing the number of STR loci included in the European Standard Set (ESS). The PowerPlex ESX 17 and ESI 17 Systems utilize different PCR primer combinations to co-amplify the following 17 loci: D1S1656, D2S441, D2S1338, D3S1358, D8S1179, D10S1248, D12S391, D16S539, D18S51, D19S433, D21S11, D22S1045, FGA, TH01, vWA, SE33, and the sex-typing locus amelogenin. A total of 1443 U.S. population samples were evaluated with pre-commercialization versions of both kits. Stutter and heterozygote peak height ratios have been used to characterize kit performance. Typing results have been used to estimate the match probabilities provided by the chosen loci as well as in concordance studies. Full concordance between the typing results for the two kits was observed in 99.994% (49,055 out of 49,062) STR allele calls compared. All genotyping discrepancies were confirmed by DNA sequence analysis. As a result of these comparisons, a second forward primer for the D22S1045 locus has been added to the PowerPlex ESX 17 System to address a primer binding site mutation and the D1S1656 locus reverse primer in the PowerPlex ESI 17 System was modified to eliminate an amplification-efficiency reducing primer dimer. PMID:20457109

Hill, Carolyn R; Duewer, David L; Kline, Margaret C; Sprecher, Cynthia J; McLaren, Robert S; Rabbach, Dawn R; Krenke, Benjamin E; Ensenberger, Martin G; Fulmer, Patricia M; Storts, Douglas R; Butler, John M

2010-04-22

209

The contrast study of anammox-denitrifying system in two non-woven fixed-bed bioreactors (NFBR) treating different low C/N ratio sewage.  

PubMed

Two non-woven fixed-bed bioreactors (NFBR) based on different substrates (nitrite and nitrate) were constructed to study the environmental adaptability for temperature and organic matter of anammox-denitrifying system and nitrogen removal performance. The two reactors were successfully operated for 200 days. The average removal rates of nitrogen and COD of R2 were 81% and 93%, respectively. Besides, the nitrogen removal rate of R1 was 95% under not more than 105 mg/l of COD. The experimental results indicated that the R2 based on nitrate had a good nitrogen removal performance at room temperature (25 °C). Additionally, the analysis results of fluorescence in situ hybridization (FISH) showed that the percentage compositions of anammox in R1 and R2 were 84% and 65% on day 189. Finally, the possible nitrogen removal model of anammox-denitrifying system was constructed. According to nitrogen balance and C/N ratios of denitrification, the nitrogen removal approaches of R1 and R2 were obtained. PMID:22446054

Gao, Fan; Zhang, Hanmin; Yang, Fenglin; Qiang, Hong; Zhang, Guangyi

2012-03-07

210

Material flows generated by pyromet copper smelting  

USGS Publications Warehouse

Copper production through smelting generates large volumes of material flows. As copper contained in ore becomes copper contained in concentrate to be fed into the smelting process, it leaves behind an altered landscape, sometimes mine waste, and always mill tailings. Copper concentrate, fluxing materials, fuels, oxygen, recyclables, scrap and water are inputs to the process. Dust (recycled), gases - containing carbon dioxide (CO2) (dissipated) and sulfur dioxide (SO2) (mostly collected, transformed and sold) and slag (discarded or sold) - are among the significant process outputs. This article reports estimates of the flows of these input/output materials for a particular set of smelters studied in some countries.

Goonan, T. G.

2005-01-01

211

Design, fabrication and characterization of high-stroke high-aspect ratio micro electro mechanical systems deformable mirrors for adaptive optics  

NASA Astrophysics Data System (ADS)

Adaptive optic (AO) systems for next generation of extremely large telescopes (30--50 meter diameter primary mirrors) require high-stroke (10 microns), high-order (100x100) deformable mirrors at lower-cost than current technology. The required specifications are achievable with Micro Electro Mechanical Systems (MEMS) devices fabricated with high-aspect ratio processing techniques. This dissertation will review simulation results compared with displacement measurements of actuators utilizing a white-light interferometer. It will also review different actuator designs, materials and post-processing procedures fabricated in three different high-aspect ratio processes, Microfabrica's Electrochemical Fabrication (EFAB(TM)), HT-Micro's Precision Fabrication Technology (HTPF(TM)), and Innovative Micro Technologies (IMT) fabrication process. These manufacturing processes allow high-precision multilayer fabrication and their sacrificial layer thicknesses can be specified by the designer, rather than by constraints of the fabrication process. Various types of high-stroke gold actuators for AO consisting of folded springs with rectangular and circular membranes as well as X-beam actuators supported diagonally by beams were designed, simulated, fabricated, and tested individually and as part of a continuous facesheet DM system. The design, modeling and simulation of these actuators are compared to experimental measurements of their pull-in voltages, which characterizes their stiffness and maximum stroke. Vertical parallel plate ganged actuators fabricated with the EFAB(TM) process have a calculated pull-in voltage of 95V for a 600mum size device. In contrast, the pull-in voltages for the comb-drive actuators ranged from 55V for the large actuator, to 203V for the smallest actuator. Simulations and interferometer scans of actuator designs fabricated with HT-Micro's Precision Fabrication (HTPF(TM)) two wafer bonded process with different spring supports have shown the ability of the actuators to achieve displacements of 1/3 of the initial gap between the spring layer and the counter electrode. Actuators and DM displacement vs. voltage have been measured with an interferometer and the corresponding results were compared to Finite Element Analysis (FEA) simulations. Simulations and interferometer scans have shown the ability of the actuators to achieve displacements of greater than 1/3 of the initial gap. A stroke of ˜9.4mum has been achieved by a DM, thus showing that this fabrication process holds promise in the manufacturing of future MEMS DMs for the next generation of extremely large telescopes. A monolithic fabrication approach for integrating a faceplate on top of an actuator array from Innovative Micro Technologies has been investigated. This monolithic approach has the ability to deposit thicker layers (tens of micrometers) of structural and sacrificial materials than that of a surface micro machining processes. This fabrication process will allow the DMs to provide both high-stoke and high-order corrections, thus eliminating the need for a woofer-tweeter DM configuration. Both the actuator and the facesheet were fabricated monolithically in gold plated onto a thermally matched ceramic-glass substrate (WMS-15) using IMT's high-aspect ratio fabrication process.

Fernandez Rocha, Bautista

212

Comparison of entrance exposure and signal-to-noise ratio between an SBDX prototype and a wide-beam cardiac angiographic system  

SciTech Connect

The scanning-beam digital x-ray (SBDX) system uses an inverse geometry, narrow x-ray beam, and a 2-mm thick CdTe detector to improve the dose efficiency of the coronary angiographic procedure. Entrance exposure and large-area iodine signal-to-noise ratio (SNR) were measured with the SBDX prototype and compared to that of a clinical cardiac interventional system with image intensifier (II) and charge coupled device (CCD) camera (Philips H5000, MRC-200 x-ray tube, 72 kWp max). Phantoms were 18.6-35.0 cm acrylic with an iohexol-equivalent disk placed at midthickness (35 mg/cm{sup 2} iodine radiographic density). Imaging was performed at 15 frame/s, with the disk at mechanical isocenter and an 11-cm object-plane field width. The II/CCD system was operated in cine mode with automatic exposure control. With the SBDX prototype at maximum x-ray output (120 kVp, 24.3 kWp), the SBDX SNR was 107%-69% of the II/CCD SNR, depending on phantom thickness, and the SBDX entrance exposure rate was 10.7-9.3 R/min (9.4-8.2 cGy/min air kerma). For phantoms where an equal-kVp imaging comparison was possible ({>=}23.3 cm), the SBDX SNR ranged from 47% to 69% of the II/CCD SNR while delivering 6% to 9% of the II/CCD entrance exposure rate. From these measurements it was determined that the relative SBDX entrance exposure at equal SNR would be 31%-16%. Results were consistent with a model for relative entrance exposure at equal SNR, which predicted a 3-7 times reduction in entrance exposure due to SBDX's comparatively low scatter fraction (5.5%-8.1% measured, including off-focus radiation), high detector detective quantum efficiency (66%-73%, measured from 70 to 120 kVp), and large entrance field area (1.7x-2.3x, for the same object-plane field width). With improvements to the system geometry, detector, and x-ray source, SBDX technology is projected to achieve conventional cine-quality SNR over a full range of patient thicknesses, with 5-10 times lower skin dose.

Speidel, Michael A.; Wilfley, Brian P.; Star-Lack, Josh M.; Heanue, Joseph A.; Betts, Timothy D.; Van Lysel, Michael S. [Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); NexRay, Inc., Los Gatos, California 95030 (United States); Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Department of Medicine and Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin 53792 (United States)

2006-08-15

213

Maximum ratio transmission  

Microsoft Academic Search

This paper presents the concept, principles, and analysis of maximum ratio transmission for wireless communications, where multiple antennas are used for both transmission and reception. The principles and analysis are applicable to general cases, including maximum-ratio combining. Simulation results agree with the analysis. The analysis shows that the average overall signal-to-mise ratio (SNR) is proportional to the cross correlation between

Titus K. Y. Lo

1999-01-01

214

Marine Respiration Ratios  

Microsoft Academic Search

Considerable confusion exists regarding the choice of numerical values for the so-called Redfield ratios. Most often quoted are those determined by Redfield himself O2 : C : N : P = 138 : 106 : 16 : 1. He determined these ratios based on the bulk chemical composition of plankton as well as changes in the chemical compositions observed in

W. S. Broecker; T. Takahashi

2003-01-01

215

Note: An advanced in situ diagnostic system for characterization of electric propulsion thrusters and ion beam sources  

NASA Astrophysics Data System (ADS)

We present an advanced diagnostic system for in situ characterization of electric propulsion thrusters and ion beam sources. The system uses a high-precision five-axis positioning system with a modular setup and the following diagnostic tools: a telemicroscopy head for optical imaging, a triangular laser head for surface profile scanning, a pyrometer for temperature scanning, a Faraday probe for current density mapping, and an energy-selective mass spectrometer for beam characterization (energy and mass distribution, composition). The capabilities of our diagnostic system are demonstrated with a Hall effect thruster SPT-100D EM1.

Bundesmann, C.; Tartz, M.; Scholze, F.; Leiter, H. J.; Scortecci, F.; Gnizdor, R. Y.; Neumann, H.

2010-04-01

216

Fixed-ratio punishment.  

PubMed

Responses were maintained by a variable-interval schedule of food reinforcement. At the same time, punishment was delivered following every nth response (fixed-ratio punishment). The introduction of fixed-ratio punishment produced an initial phase during which the emission of responses was positively accelerated between punishments. Eventually, the degree of positive acceleration was reduced and a uniform but reduced rate of responding emerged. Large changes in the over-all level of responding were produced by the intensity of punishment, the value of the punishment ratio, and the level of food deprivation. The uniformity of response rate between punishments was invariant in spite of these changes in over-all rate and contrary to some plausible a priori theoretical considerations. Fixed-ratio punishment also produced phenomena previously observed under continuous punishment: warm-up effect and a compensatory increase. This type of intermittent punishment produced less rapid and less complete suppression than did continuous punishment. PMID:13965779

AZRIN, N H; HOLZ, W C; HAKE, D F

1963-04-01

217

Evaluation of the effect of the stoichiometric ratio of Ca\\/Cu on the electrical and microstructural properties of the CaCu3Ti4O12 polycrystalline system  

Microsoft Academic Search

The structural, microstructural, non-ohmic and dielectric properties of perovskite-type CaCu3Ti4O12 (CCTO) with Ca\\/Cu stoichiometries of 1\\/3, 1\\/1 and 3\\/1 are discussed. The 1\\/3 Ca\\/Cu ratio system presents very high dielectric permittivity (~9000 at 10 kHz) and a low non-ohmic property (alpha = 9), whereas the 1\\/1 Ca\\/Cu ratio system shows the opposite effect, i.e. the dielectric permittivity decreases (2740 at

M. A. Ramírez; P. R. Bueno; R. Tararam; A. A. Cavalheiro; E. Longo; J. A. Varela

2009-01-01

218

Further stratification of patients with multiple myeloma by International Staging System in combination with ratio of serum free ? to ? light chains.  

PubMed

The serum free light chain (sFlc) levels were measured for 122 Chinese patients with newly diagnosed symptomatic multiple myeloma (NDSMM), and ?/? ratios (rFlc) were calculated. The data were analyzed for the roles of sFlc and rFlc in the diagnosis and prognosis of MM. Abnormal sFlc and/or rFlc were detected in 99.2% of patients, demonstrating that the FLC assay is much more sensitive than the commonly used methods. Baseline sFlc and rFlc successfully predicted the overall survival (OS). The median OS was not reached (NR) versus 23 months for the low sFLC group (sFLC-? < 180 mg/L or sFLC-? < 592.5 mg/L) and high sFLC group (sFLC-? ? 180 mg/L or sFLC-? ? 592.5 mg/L) (p = 0.001), and NR versus 21 months for the low rFLC group (0.04 ? rFLC ? 25) and high rFLC group (p < 0.001), respectively. Interestingly, the significant differences in OS between the low and high rFLC groups were not changed by bortezomib chemotherapy. In addition, patients were further stratified by three novel poor-prognosis factors (?(2)-microglobulin [?2-MG] > 3.5 mg/L, albumin [ALB] < 35 g/L, rFLC > 25 or rFLC < 0.04) that were developed from combination of the rFlc with the International Staging System (ISS): the low risk group (no factor), the low-intermediate risk group (one factor), the high-intermediate risk group (two factors) and the high risk group (three factors). The median OS for those groups was NR, NR, 24 months and 13 months, respectively (p < 0.05). In conclusion, the sFLC assay was highly sensitive in the diagnosis of MM in Chinese patients. The prognostic potential of the ISS may be improved with the addition of rFLC. PMID:22712834

Xu, Yan; Sui, Weiwei; Deng, Shuhui; An, Gang; Wang, Yafei; Xie, Zhenqing; Yao, Hongjing; Zhu, Guoqing; Zou, Dehui; Qi, Junyuan; Hao, Mu; Zhao, Yaozhong; Wang, Jianxiang; Chen, Tao; Qiu, Lugui

2012-09-05

219

Cruise Performance of an Isolated 1.15 Pressure Ratio Turbofan Propulsion System Simulator at Mach Numbers from 0.6 to 0.85.  

National Technical Information Service (NTIS)

An isolated 1.15 pressure ratio turbofan engine simulator was tested at Mach numbers from 0.6 to 0.85. At Mach 0.75 the net propulsive force of the fan and nacelle (excluding core thrust) was 73 percent of the ideal fan net thrust. Internal losses amounte...

F. W. Steffen

1974-01-01

220

A Novel Filter Construction Utilizing HTS Reaction-Type Filter to Improve Adjacent Channel Leakage Power Ratio of Mobile Communication Systems  

Microsoft Academic Search

We propose a new band selective stop filter construction to decrease the out of band intermodulation distortion (IMD) noise generated in the transmitting power amplifier. Suppression of IMD noise directly improves the adjacent channel leakage power ratio (ACLR). A high-temperature superconducting (HTS) device with extremely high-Q performance with very small hybrid IC pattern would make it possible to implement the

Shunichi Futatsumori; Takashi Hikage; Toshio Nojima; Akihiko Akasegawa; Teru Nakanishi; Kazunori Yamanaka

2009-01-01

221

Air/fuel ratio regulator  

SciTech Connect

A description is given of an air/fuel ratio regulator for use with the fuel injection control system of an internal combustion engine of the spark ignition type having an air and exhaust gas (gas) induction passage open at one end to air at ambient pressure level and connected at its other end to the engine combustion chamber to be subject to manifold vacuum changes therein, a throttle valve rotatably mounted for movement across the passage to control the gas flow therethrough, exhaust gas recirculation (egr) passage means connecting engine exhaust gases to the induction passage above the closed position of the throttle valve, an egr flow control valve mounted in the egr passage means for movement between open and closed postions to control the volume of egr gas flow, an engine speed responsive positive displacement type fuel injection pump having a fuel flow output to the engine that varies in direct proportion to changes in engines speed to match fuel flow and mass airflow through the induction system of the engine over the entire speed and load range of the engine to maintain the intake mixture ratio of air to fuel constant, the pump having a fuel flow control lever movable to vary the fuel rate of flow, the regulator being characterized by engine manifold vacuum responsive first servo means operably connected to the fuel control lever for maintaining a constant air/fuel (A/F) ratio by changing fuel output as a function of changing manifold vacuum and air flow upon opening of the throttle valve, a fuel enrichment control lever operably connected to the pump control lever and movable to modify the position of the pump lever dictated by the first servo means to change the A/F ratio, and further means responsive to engine operating conditions for moving the fuel enrichment control lever to provide the changed A/F ratio.

Simko, A.

1980-07-22

222

Luminescence ratio indicators for oxygen  

SciTech Connect

To improve stability of optical sensors with respect to calibration, the authors developed oxygen indicator systems which have two luminescence bands, one of which is quenched by oxygen while the other is relatively unaffected by oxygen. The measured parameter is the relative intensity of the two bands. The following systems have been evaluated: (1) In water in the presence of ..gamma..-cyclodextrin, the ratio of pyrene monomer fluorescence to pyrene dimer fluorescence decreases with increasing oxygen partial pressure. (2) In water in the presence of ..beta..-cyclodextrin, the ratio of bromonaphthalene phosphorescence to fluorescence decreases with increasing oxygen partial pressure. (3) Bromonaphthoyl derivatives extracted into ..gamma..-cyclodextrin bonded to cellulose and dried show intense oxygen-dependent phosphorescence and oxygen-independent fluorescence. Of these, system 3 is most practical because it is more stable and has higher intensities with a larger change in intensity ratio. However, it is limited to measurements in dry samples, because 100% relative humidity is sufficient to quench phosphorescence.

Lee, E.D.; Werner, T.C.; Seitz, W.R.

1987-01-15

223

The Golden Ratio  

NSDL National Science Digital Library

This Web site provides a "basic introduction to one of the most amazing discoveries in mathematics: the Golden Ratio." Created by David L. Narain, this site offers a particularly engaging way to bring together math and the natural sciences in the classroom. Seven straightforward activities have students construct a golden rectangle and spiral, and also explore the Golden Ratio in nature and in other contexts. The site also includes a quiz; answers are not provided, though. The activities are designed for 9th and 10th graders, but would also be appropriate for middle school students.

Narain, David L.

2001-01-01

224

Formation and Evolution of the Disk System of the Milky Way: [alpha/Fe] Ratios and Kinematics of the SEGUE G-Dwarf Sample  

SciTech Connect

We employ measurements of the [{alpha}/Fe] ratio fromlow-resolution (R {approx} 2000) spectra of 17,500 G-type dwarfs included in SDSS Data Release 8, selected using simple and well-understood selection criteria, to separate them into likely thin- and thick-disk subsamples. This classification, based on chemistry, is strongly motivated by the bi-modal distribution of stars in the [{alpha}/Fe] vs. [Fe/H] diagram. The resulting subsamples allow, for the first time, investigations of the kinematic behavior of thin- and thick-disk stars as a function of metallicity and position up to distances of 3 kpc from the Galactic plane. Both subsamples exhibit strong gradients of orbital rotational velocity with metallicity, but with opposite signs (-20 to -30 km s{sup -1} dex{sup -1} for the thin-disk population, and +40 to +50 km s{sup -1} dex{sup -1} for the thick-disk population). We find that the rotational velocity decreases with the distance from the plane for both disk components, with similar slopes (10 km s{sup -1} kpc{sup -1}), and a nearly constant difference in the mean rotational velocity of about 30 km s{sup -1}. The mean rotational velocity is uncorrelated with Galactocentric distance for the thin-disk subsample, and exhibits only a marginally significant correlation for the thick-disk subsample. Thick-disk stars exhibit a very strong trend of orbital eccentricity with metallicity (-0.2 dex{sup -1}), while the eccentricity does not change with metallicity for the thin-disk subsample. The eccentricity is almost independent of Galactocentric radius for the thin-disk stars, while a marginal gradient of the eccentricity with distance exists for the thick-disk population. Both subsamples possess similar trends of increasing eccentricity with distance from the Galactic plane, with a constant difference of about 0.1. The shapes of the overall distributions of orbital eccentricity for the thin- and thick-disk populations are quite different from one another, independent of distance from the plane; neither subsample has significant numbers of stars with eccentricity above 0.6. These observational results provide strong new constraints on models for the formation and evolution of the Milky Way's disk system. For example, the observed dependence of the mean rotational velocity on metallicity for thin-disk stars is inconsistent with predictions from classical local chemical evolution models. We also consider the predictions of several contemporary models of disk evolution, such as radial migration, gas-rich mergers, disk heating, and pure accretion models. We find that radial migration appears to have played an important role in the evolution of the thin-disk population, but possibly less so, relative to the gas-rich merger or disk heating scenarios, for the thick disk. Pure accretion models appear to be ruled out by the observed distribution of eccentricities for thick-disk stars. We emphasize that more physically realistic models, and simulations that probe a greater range of disk formation scenarios, need to be constructed in order to carry out the detailed quantitative comparisons that our new data enable.

Lee, Young Sun; /Michigan State U.; Beers, Timothy C.; /Michigan State U.; An, Deokkeun; /Ewha Women's U., Seoul; Ivezic, Zeljko; /Washington U., Seattle, Astron. Dept.; Just, Andreas; /Heidelberg U.; Rockosi, Constance M.; /Lick Observ.; Morrison, Heather L.; /Case Western Reserve U.; Johnson, Jennifer A.; /Ohio State U.; Schonrich, Ralph; /Garching, Max Planck Inst.; Bird, Jonathan; /Ohio State U.; Yanny, Brian; /Fermilab /Case Western Reserve U.

2011-04-01

225

Area Ratios of Quadrilaterals.  

ERIC Educational Resources Information Center

Shows that the ratio of the area of the quadrilateral formed by joining the kth points to the area of the original quadrilateral is constant whether it is convex or concave quadrilateral. Presents many geoboard or dot paper diagrams and geometrical expresssions. (YP)

Anderson, David R.; Arcidiacono, Michael J.

1989-01-01

226

Fuel efficiency ratio  

Microsoft Academic Search

Example of calculations are shown to illustrate how fuel costs and solid waste yardage are related. A commercial front loader is used for the examples, but any vehicle can be substituted using the same mathematical concept. Three new ratios, engine efficiency, fuel efficiency, and per yard fuel cost, that may enter the refuse industry in the 1980s are discussed. (MCW)

1980-01-01

227

The Likelihood Ratio Test  

NSDL National Science Digital Library

This module, created by Don Johnson of Rice University, provides an explanation and an example of the likelihood ratio test. Topics include: decision regions, Bayes' decision criterion, Bayes' cost, and likelihood function. The site is enhanced by Johnson's use of graphic and numerical demonstrations to better explain his points. Additionally, a PDF attachment providing an in-depth explanation is also featured.

Johnson, Don

2009-01-08

228

Digit ratio in birds.  

PubMed

The Homeobox (Hox) genes direct the development of tetrapod digits. The expression of Hox genes may be influenced by endogenous sex steroids during development. Manning (Digit ratio. New Brunswick, NJ: Rutgers University Press, 2002) predicted that the ratio between the lengths of digits 2 (2D) and 4 (4D) should be sexually dimorphic because prenatal exposure to estrogens and androgens positively influence the lengths of 2D and 4D, respectively. We measured digits and other morphological traits of birds from three orders (Passeriformes, house sparrow, Passer domesticus; tree swallow, Tachycineta bicolor; Pscittaciformes, budgerigar, Melopsittacus undulates; Galliformes, chicken, Gallus domesticus) to test this prediction. None were sexually dimorphic for 2D:4D and there were no associations between 2D:4D and other sexually dimorphic traits. When we pooled data from all four species after we averaged right and left side digits from each individual and z-transformed the resulting digit ratios, we found that males had significantly larger 2D:4D than did females. Tetrapods appear to be sexually dimorphic for 2D:4D with 2D:4D larger in males as in some birds and reptiles and 2D:4D smaller in males as in some mammals. The differences between the reptile and mammal lineages in the directionality of 2D:4D may be related to the differences between them in chromosomal sex determination. We suggest that (a) natural selection for a perching foot in the first birds may have overridden the effects of hormones on the development of digit ratio in this group of vertebrates and (b) caution be used in making inferences about prenatal exposure to hormones and digit ratio in birds. PMID:18833568

Lombardo, Michael P; Thorpe, Patrick A; Brown, Barbara M; Sian, Katie

2008-12-01

229

What's My Ratio?  

NSDL National Science Digital Library

In this activity, students use linear measurement and calculators to investigate proportionality and determine the constant ratio between similar figures. In it, students draw a figure on centimeter graph paper, increase or decrease the size, and predict the dimensions. Then students compare the ratio of two pictures by measuring, recording their data, and discussing their findings to draw conclusions. Suggested guidelines for instruction and classroom discussion are included, as well as data collection worksheets for students, and centimeter graph paper to print. The lesson may be introduced by reading appropriate sections from "GoosebumpsâMonster Blood III" (Chapters 15 and 16) by R.L. Stine, or "The Shrinking of Treehorn" by F. Heide.

2003-01-01

230

The Golden Ratio Encoder  

Microsoft Academic Search

This paper proposes a novel Nyquist-rate analog-to-digital (A\\/D) conversion algorithm which achieves exponential accuracy in the bit-rate despite using imperfe ct components. The proposed algorithm is based on a robust implementation of a beta-encoder with ? = ? = (1 + ? 5)\\/2, the golden ratio. It was previously shown that beta-encoders can be implemented in such a way that

Ingrid Daubechies; C. Sinan Güntürk; Yang Wang; Özgür Yilmaz

2008-01-01

231

Thinking Blocks: Ratios  

NSDL National Science Digital Library

This set of six interactive Flash activities gives students an opportunity to visually model and calculate the unknown quantity from ratios and other information, all in the context of solving word problems. A video demonstration introduces each method, and then students work on modeling and solving five problems. Students can check their modeling of the problem at intermediate stages. Teachers can track a student's progress throughout the problem set.

2012-01-01

232

PROPORTIONS and RATIOS  

NSDL National Science Digital Library

Using what you already know and the text, can you solve these problems? Just by looking at the titles below, describe in your journal what you think each activity is going to be about and how it relates to proportions and ratios. Which tastes juicier? Statue of Liberty : is the Statue of Liberty's nose too long? Describe in your journal how your favorite question above was answered. Also, include any fun facts you learned along the way. What ...

Squire, Mrs.

2009-04-13

233

Niobium and Ta in carbonaceous chondrites: constraints on the solar-system and primitive mantle Nb/Ta, Zr/Nb and Nb/U ratios  

NASA Astrophysics Data System (ADS)

We have determined Nb, Y, and Zr abundances in the carbonaceous chondrites Orgueil (CI), Murray (CM2), Murchison (CM2), Allende (CV3), and Karoonda (CK4) and in the eucrites Pasamonte, and Juvinas by a recently developed spark source mass spectrometric technique using multiple ion counting (MIC-SSMS). The abundance of Ta was determined in the same meteorites by radiochemical neutron activation analysis (RNAA). Precision of the MIC-SSMS and RNAA techniques is about 3% and = 5%, respectively. The new abundances for CI chondrites are: Nb=0.247, Ta=0.0142, Zr=3.86, Y=1.56 ?g/g, or 0.699, 0.0202, 11.2, 4.64 atoms/106 Si atoms, respectively. The values agree with earlier compilations, but they are a factor of 2 more precise than earlier analyses. Trace element concentrations in the CM, CV, and CK chondrites are higher than in the CI chondrite Orgueil by about 37, 86, and 120%, respectively, in agreement with the variable absolute contents of refractory lithophile elements in different groups of carbonaceous chondrites. Of particular interest are the chondritic Nb/Ta, Zr/Nb, and Nb/U ratios, because these ratios are important tools to interpret the chemical evolution of planetary bodies. We obtained Nb/Ta=17.4±0.5 for the carbonaceous chondrites and the Juvinas-type eucrites investigated. This value is similar to, however much more precise than previous estimates. The same is true for Zr/Nb (15.5±0.2) and Zr/Y (2.32±0.12). In combination with recently published MIC-SSMS U data for carbonaceous chondrites, we obtained a chondritic Nb/U ratio of 29±2. Because Nb, Ta, Zr, Y, and U are refractory lithophile elements and presumably partitioned into the silicate phase of the Earth during core formation, the element ratios may also be used to constrain evolution of the Earth's primitive mantle, and with the more precise determinations fractionation of Nb and Ta during magmatic processes and mantle-crust interactions can now be interpreted with greater confidence.

Jochum, K. P.; Stolz, A. J.; McOrist, G.

2000-03-01

234

Effects of speckle/pixel size ratio on temporal and spatial speckle-contrast analysis of dynamic scattering systems: Implications for measurements of blood-flow dynamics  

PubMed Central

Laser Speckle Contrast Imaging (LSCI) is an optical technique used to generate blood flow maps with high spatial and temporal resolution. It is well known that in LSCI, the speckle size must exceed the Nyquist criterion to maximize the speckle's pattern contrast. In this work, we study experimentally the effect of speckle-pixel size ratio not only in dynamic speckle contrast, but also on the calculation of the relative flow speed for temporal and spatial analysis. Our data suggest that the temporal LSCI algorithm is more accurate at assessing the relative changes in flow speed than the spatial algorithm.

Ramirez-San-Juan, J. C.; Mendez-Aguilar, E.; Salazar-Hermenegildo, N.; Fuentes-Garcia, A.; Ramos-Garcia, R.; Choi, B.

2013-01-01

235

Handy Measuring Ratio  

NSDL National Science Digital Library

In this activity, learners use their hands as tools for indirect measurement. Learners explore how to use ratios to calculate the approximate height of something that can't be measured directly by first measuring something that can be directly measured. This activity can also be used to explain how scientists use indirect measurement to determine distances between things in the universe that are too far away, too large or too small to measure directly (i.e. diameter of the moon or number of bacteria in a volume of liquid).

Exploratorium

2010-01-01

236

Sensor of Ratios of Absolute Gas Pressures.  

National Technical Information Service (NTIS)

The article describes a sensor of ratios of absolute gas pressures containing elastic sensitive elements picking up pressures and acting on a compensation spring system transmitting the force onto a tensometric converter which for the purpose of improving...

G. I. Tyukel L. A. Pletnev

1967-01-01

237

Measurements of NO2 mixing ratios with topographic target light scattering-differential optical absorption spectroscopy system and comparisons to point monitoring technique  

NASA Astrophysics Data System (ADS)

A topographic target light scattering-differential optical absorption spectroscopy (ToTaL-DOAS) system is developed for measuring average concentrations along a known optical path and studying surface-near distributions of atmospheric trace gases. The telescope of the ToTaL-DOAS system points to targets which are located at known distances from the measurement device and illuminated by sunlight. Average concentrations with high spatial resolution can be retrieved by receiving sunlight reflected from the targets. A filed measurement of NO2 concentration is performed with the ToTaL-DOAS system in Shijiazhuang in the autumn of 2011. The measurement data are compared with concentrations measured by the point monitoring technique at the same site. The results show that the ToTaL-DOAS system is sensitive to the variation of NO2 concentrations along the optical path.

Wang, Yang; Li, Ang; Xie, Pin-Hua; Zeng, Yi; Wang, Rui-Bin; Chen, Hao; Pei, Xian; Liu, Jian-Guo; Liu, Wen-Qing

2012-11-01

238

A Novel Filter Construction Utilizing HTS Reaction-Type Filter to Improve Adjacent Channel Leakage Power Ratio of Mobile Communication Systems  

NASA Astrophysics Data System (ADS)

We propose a new band selective stop filter construction to decrease the out of band intermodulation distortion (IMD) noise generated in the transmitting power amplifier. Suppression of IMD noise directly improves the adjacent channel leakage power ratio (ACLR). A high-temperature superconducting (HTS) device with extremely high-Q performance with very small hybrid IC pattern would make it possible to implement the proposed filter construction as a practical device. To confirm the effectiveness of the HTS reaction-type filter (HTS-RTF) in improving ACLR, investigations based on both experiments and numerical analyses are carried out. The structure of a 5-GHz split open-ring resonator is investigated; its targets include high-unload Q-factor, low current densities, and low radiation. A designed 5-GHz HTS-RTF with 4MHz suppression bandwidth and more than 40dB MHz-1 sharp skirt is fabricated and experimentally investigated. The measured ACLR values are improved by a maximum of 12.8dB and are constant up to the passband signal power of 40dBm. In addition, to examine the power efficiency improvement offered by noise suppression of the HTS-RTF, numerical analyses based on measured results of gallium nitride HEMT power amplifier characteristics are conducted. The analyzed results shows the drain efficiency of the amplifier can be improved to 44.2% of the amplifier with the filter from the 15.7% of the without filter.

Futatsumori, Shunichi; Hikage, Takashi; Nojima, Toshio; Akasegawa, Akihiko; Nakanishi, Teru; Yamanaka, Kazunori

239

Uranium casting furnace automatic temperature control development.  

National Technical Information Service (NTIS)

Development of an automatic molten uranium temperature control system for use on batch-type induction casting furnaces is described. Implementation of a two-color optical pyrometer, development of an optical scanner for the pyrometer, determination of fur...

R. F. Lind

1992-01-01

240

The Potential of a Partial-Flow Constant Dilution Ratio Sampling System as a Candidate for Vehicle Exhaust Aerosol Measurements Leonidas Ntziachristos  

Microsoft Academic Search

This paper presents the measurement of airborne particle properties with use of a dedicated sampling protocol and a measurement setup directly installed in the exhaust line of vehicles and engines. The sampling system dilutes a small part of the exhaust directly at the tailpipe without the need of exhaust gas transfer lines that may lead to sampling artifacts. Dilution takes

Leonidas Ntziachristos; Zissis Samaras

2010-01-01

241

FORMATION AND EVOLUTION OF THE DISK SYSTEM OF THE MILKY WAY: [{alpha}/Fe] RATIOS AND KINEMATICS OF THE SEGUE G-DWARF SAMPLE  

SciTech Connect

We employ measurements of the [{alpha}/Fe] ratio derived from low-resolution (R {approx} 2000) spectra of 17,277 G-type dwarfs from the SEGUE survey to separate them into likely thin- and thick-disk subsamples. Both subsamples exhibit strong gradients of orbital rotational velocity with metallicity, of opposite signs, -20 to -30 km s{sup -1} dex{sup -1} for the thin-disk and +40 to +50 km s{sup -1} dex{sup -1} for the thick-disk population. The rotational velocity is uncorrelated with Galactocentric distance for the thin-disk subsample and exhibits a small trend for the thick-disk subsample. The rotational velocity decreases with distance from the plane for both disk components, with similar slopes (-9.0 {+-} 1.0 km s{sup -1} kpc{sup -1}). Thick-disk stars exhibit a strong trend of orbital eccentricity with metallicity (about -0.2 dex{sup -1}), while the eccentricity does not change with metallicity for the thin-disk subsample. The eccentricity is almost independent of Galactocentric radius for the thin-disk population, while a marginal gradient of the eccentricity with radius exists for the thick-disk population. Both subsamples possess similar positive gradients of eccentricity with distance from the Galactic plane. The shapes of the eccentricity distributions for the thin- and thick-disk populations are independent of distance from the plane, and include no significant numbers of stars with eccentricity above 0.6. Among several contemporary models of disk evolution that we consider, radial migration appears to have played an important role in the evolution of the thin-disk population, but possibly less so for the thick disk, relative to the gas-rich merger or disk heating scenarios. We emphasize that more physically realistic models and simulations need to be constructed in order to carry out the detailed quantitative comparisons that our new data enable.

Lee, Young Sun; Beers, Timothy C. [Department of Physics and Astronomy and JINA (Joint Institute for Nuclear Astrophysics), Michigan State University, East Lansing, MI 48824 (United States); An, Deokkeun [Department of Science Education, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Ivezic, Zeljko [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195-1580 (United States); Just, Andreas [Astronomisches Rechen-Institut, Zentrum fuer Astronomie der Universitaet Heidelberg (ZAH), Moenchhofstr. 12-14, 69120 Heidelberg (Germany); Rockosi, Constance M. [UCO/Lick Observatory, Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Morrison, Heather L.; Harding, Paul [Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106 (United States); Johnson, Jennifer A.; Bird, Jonathan [Department of Astronomy, Ohio State University, Columbus, OH 43210 (United States); Schoenrich, Ralph [Max-Planck-Institute fuer Astrophysik, Karl-Schwarzschild-Str. 1, D-85741 Garching (Germany); Yanny, Brian [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Rocha-Pinto, Helio J., E-mail: lee@pa.msu.edu, E-mail: beers@pa.msu.edu [Universidade Federal do Rio de Janeiro, Observatorio do Valongo, Lad. Pedro Antonio 43, 20080-090 Rio de Janeiro (Brazil)

2011-09-10

242

A signal input coil made of superconducting thin film for improved signal-to-noise ratio in a high-Tc SQUID-based ultra-low field nuclear magnetic resonance system  

NASA Astrophysics Data System (ADS)

Resonant coupling schemes are commonly used in SQUID-based ultra-low field (ULF) nuclear magnetic resonance (NMR) systems to couple the spin relaxation signals from samples to the SQUID. Generally, in NMR systems, a resonant coupling scheme is composed of two solenoid coils which are made of enamel insulated wires and a capacitor connected in series. In this work, we tried to replace the metal solenoid input coil with a planar high-Tc superconducting spiral coil to improve the signal-to-noise ratio (SNR) of the ULF NMR signal. A measurement of the free induction decay signal of water protons was performed to demonstrate the improved performance of the system. This improvement is due to the fact that the planar superconducting spiral coil possesses a higher mutual inductance with the SQUID. Therefore, it is a promising way to enhance the SNR of high-Tc SQUID-based ULF NMR/MRI systems.

Chen, Kuen-Lin; Hsu, Chin-Wei; Ku, Yue-Bai; Chen, Hsin-Hsien; Liao, Shu-Hsien; Wang, Li-Min; Horng, Herng-Er; Yang, Hong-Chang

2013-11-01

243

Cleavage of the antitoxin of the parD toxin-antitoxin system is determined by the ClpAP protease and is modulated by the relative ratio of the toxin and the antitoxin.  

PubMed

Differential stability of toxins and antitoxins is the key for the conditional activation and function of Toxin-Antitoxin systems. Here we report the evaluation of the action of cell proteases Lon, ClpAP, ClpXP and ClpYQ on the Kis antitoxin and the Kid toxin of the parD TA system of plasmid R1. In vitro analysis shows that Kis antitoxin, but not the Kid toxin, is cleaved specifically by the ClpAP protease. The Kid toxin is not cleaved either by this protease or by any of the others cell proteases tested but in complex with the Kis antitoxin protects the cleavage of this protein in a way that is dependent on the toxin-antitoxin ratio. We further show that this protection is correlated with the inability of the ClpA chaperone to access the Kis antitoxin when in complex with Kid toxin. The stability of the antitoxin greatly increases in vivo in a clpP- background and plasmid maintenance mediated by the parD system, which is dependent on the differential decay of the antitoxin, is reduced to the levels observed in the absence of a functional toxin. The functional implications of these data are further discussed within the frame of the regulation of the parD system and of the available information on the nature of the toxin-antitoxin complexes formed at different toxin-antitoxin ratios. PMID:23419648

Diago-Navarro, Elizabeth; Hernández-Arriaga, Ana María; Kubik, Slawomir; Konieczny, Igor; Díaz-Orejas, Ramón

2013-02-15

244

Usefulness of the organ culture system when villous height/crypt depth ratio, intraepithelial lymphocyte count, or serum antibody tests are not diagnostic for celiac disease.  

PubMed

The existence of mild forms of celiac disease (CD) can make the histology-based diagnosis difficult to reach. Since anti-endomysium (EMA) and anti-tissue transglutaminase (anti-tTG) are detectable in culture supernatants of duodenal biopsies from CD patients, our aim was to assess if this system can support the histology in the diagnostic work-up. A total of 559 suspected CD patients underwent serum EMA/anti-tTG detection, upper endoscopy with duodenal biopsy sampling, histologic analysis, and organ culture to detect EMA/anti-tTG in supernatants. A subgroup of 30 patients with organ culture positive results were put on a gluten-free diet (GFD). Their gluten-dependency was evaluated by the psychological general well-being and beck depression inventory indexes. Statistical analysis was performed by Cohen k inter-test, Friedman test, and Dunn multiple comparison. Two hundred forty-one out of 559 (43.1%) patients showed intestinal villous atrophy, whereas serum and organ culture EMA/anti-tTG were positive in 293/559 (52.4%) and 334/559 (59.7%) patients, respectively. The strength of agreement resulted good for serology vs histology (k = 0.730), good for organ culture vs histology (k = 0.662), and very good for serology vs organ culture (k = 0.852). After 12 months of GFD, psychological general well-being index significantly increased, and beck depression inventory index significantly decreased (P < 0.001 for each one). Data highlight the organ culture system as a useful tool to assist the histology in diagnosing CD, mainly in cases without villous atrophy or in seronegative patients. The marked improvement in quality of life after a GFD further supports the reliability of this system in diagnosing CD. PMID:23177794

Picarelli, Antonio; Di Tola, Marco; Marino, Mariacatia; Libanori, Valerio; Borghini, Raffaele; Salvi, Elisa; Donato, Giuseppe; Vitolo, Domenico; Tiberti, Antonio; Marcheggiano, Adriana; Bassotti, Gabrio; Corazziari, Enrico

2012-11-20

245

A solid immersion interference lithography system for imaging ultra-high numerical apertures with high-aspect ratios in photoresist using resonant enhancement from effective gain media  

NASA Astrophysics Data System (ADS)

In the last year our Solid Immersion Lloyd's Mirror Interference Lithography (SILMIL) system has proved to be a successful tool for evanescent interferometric lithography (EIL). The initial goal was to use SILMIL in conjunction with the surface plasmon polariton (SPP) surface states at the resist-metal interface. Through this resonance, we aimed to counter the decay of evanescent images created using EIL. By analyzing the theory in greater detail we were able to develop a better understanding of the resonance phenomena. In this paper, details of the design of SILMIL and how one may utilize it to produce ultra-high numerical apertures (NAs) are given, as well as an introduction to the resonance phenomena and the mechanism behind it. We introduce a new method that requires a gain medium (one that has a negative loss) to achieve significant enhancements, and present an effective gain medium by using a high-index dielectric on low-index media. We present results at ? = 405 nm using such an effective gain medium and also provide a feasible design example at the lithography standard ? = 193 nm.

Mehrotra, Prateek; Mack, Chris A.; Blaikie, Richard J.

2012-03-01

246

Climatic significance of isotope ratios  

Microsoft Academic Search

The hydrogen and oxygen isotope ratios of water, which can be measured by Isotope Ratio Mass Spectrometry (IRMS), exhibit climatic dependencies and are commonly exploited in hydrogeology. More generally, the overall carbon or hydrogen isotope ratios of plant organic matter, and in particular of tree-ring cellulose, have been frequently used for climatic reconstruction. However, since many physicochemical and biochemical fractionation

Gérard J. Martin; Maryvonne L. Martin

2003-01-01

247

Evaluation of the effect of the stoichiometric ratio of Ca/Cu on the electrical and microstructural properties of the CaCu3Ti4O12 polycrystalline system  

NASA Astrophysics Data System (ADS)

The structural, microstructural, non-ohmic and dielectric properties of perovskite-type CaCu3Ti4O12 (CCTO) with Ca/Cu stoichiometries of 1/3, 1/1 and 3/1 are discussed. The 1/3 Ca/Cu ratio system presents very high dielectric permittivity (~9000 at 10 kHz) and a low non-ohmic property (? = 9), whereas the 1/1 Ca/Cu ratio system shows the opposite effect, i.e. the dielectric permittivity decreases (2740 at 10 kHz) and the non-ohmic property increases (? = 42), indicating that these properties are not directly correlated. The results of this work reinforce the idea that the greatest contribution to the very high permittivity is caused by the presence of planar defects inside the CCTO grains, generating internal nanometric domains associated with stacking faults, according to the nanoscale barrier layer capacitance model proposed very recently in the literature [1]. The non-ohmic property is related to the presence and distribution of phases such as CaTiO3 (CTO) and CuO, segregated or precipitated at the grain boundary, which generate large numbers of electrically active interfaces.

Ramírez, M. A.; Bueno, P. R.; Tararam, R.; Cavalheiro, A. A.; Longo, E.; Varela, J. A.

2009-09-01

248

Mobile, outdoor continuous-flow isotope-ratio mass spectrometer system for automated high-frequency 13C- and 18O-CO2 analysis for Keeling plot applications.  

PubMed

A continuous-flow isotope-ratio mass spectrometer (CF-IRMS, custom-made GasBenchII and Delta(plus)Advantage, ThermoFinnigan) was installed on a grassland site and interfaced with a closed-path infrared gas analyser (IRGA). The CF-IRMS and IRGA were housed in an air-conditioned travel van. Air was sampled at 1.5 m above the 0.07-m tall grassland canopy, drawn through a 17-m long PTFE tube at a rate of 0.25 L s(-1), and fed to the IRGA and CF-IRMS in series. The IRMS was interfaced with the IRGA via a stainless steel capillary inserted 0.5 m into the sample air outlet tube of the IRGA (forming an open split), a gas-tight pump, and a sample loop attached to the eight-port Valco valve of the continuous-flow interface. Air was pumped through the 0.25-mL sample loop at 10 mL s(-1) (a flushing frequency of 40 Hz). Air samples were analysed at intervals of approx. 2.8 min. Whole system precision was tested in the field using air mixed from pure CO2 and CO2-free air by means of mass flow controllers. The standard deviation of repeated single measurements was 0.21-0.07 per thousand for delta13C and 0.34-0.14 per thousand for delta18O of CO2 in air with mixing ratios ranging between 200-800 micromol mol(-1). The CO2 peak area measured by the IRMS was proportional to the CO2 mixing ratio (r2 = 1.00), allowing estimation of sample air CO2 mixing ratio from IRMS data. A 1-day long measurement cycle of CO2, delta13C and delta18O of air sampled above the grassland canopy was used to test the system for Keeling plot applications. Delta18O exhibited a clear diurnal cycle (4 per thousand range), but short-term (1-h interval) variability was small (average SD 0.38 per thousand). Yet, the correlation between delta18O and CO2 mixing ratio was relatively weak, and this was true for both the whole data set and 1-h subsets. Conversely, the delta13C of all 541 samples measured during the 25.2-h interval fitted well the Keeling regression (r2 = 0.99), yielding an intercept of -27.40 per thousand (+/-0.07 per thousand SE). Useful Keeling regressions (r2 > 0.9, average r2 = 0.96) also resulted from data collected over 1-h intervals of the 12-h long twilight and dark period. These indicated that 13C content of ecosystem respiration was approx. constant near -27.6 per thousand. The precision of the present system is similar to that of current techniques used in ecosystem studies which employ flask sampling and a laboratory-based CF-IRMS. Sampling (and measurement) frequency is greatly increased relative to systems based on flask sampling, and sampling time (0.025 s per sample) is decreased. These features increase the probability for sampling the entire CO2 range which occurs in a given time window. The system obviates sample storage problems, greatly minimises handling needs, and allows extended campaigns of high frequency sampling and analysis with minimal attendance. PMID:15543546

Schnyder, Hans; Schäufele, Rudi; Wenzel, Richard

2004-01-01

249

Air/fuel ratio controller  

SciTech Connect

An internal combustion engine has a fuel injection pump and an air/fuel ratio controller. The controller has a lever that is connected to the pump lever. An aneroid moves the controller lever as a function of changes in intake manifold vacuum to maintain a constant air/fuel ratio to the mixture charge. A fuel enrichment linkage is provided that modifies the movement of the fuel flow control lever by the aneroid in response to changes in manifold gas temperature levels and exhaust gas recirculation to maintain the constant air/fuel ratio. A manual override is provided to obtain a richer air/fuel ratio for maximum acceleration.

Schechter, M.M.; Simko, A.O.

1980-12-23

250

Assisting Manual Dolphin Identification by Computer Extraction of Dorsal Ratio  

Microsoft Academic Search

Marine biologists use a measurement called the “Dorsal Ratio” in the process of manual identification of bottlenose dolphins. The dorsal ratio denotes the relative distances of the two largest notches from the tip on the dorsal fin. The manual computation of this ratio is time consuming, labor intensive, and user dependent. This paper presents a computer-assisted system to extract the

A. Kreho; N. Kehtarnavaz; B. Araabi; G. Hillman; B. Würsig; D. Weller

1999-01-01

251

Frugality ratios and improved truthful mechanisms for vertex cover  

Microsoft Academic Search

In set-system auctions, there are several overlapping teams of agents, and a task that can be completed by any of these teams. The buyer's goal is to hire a team and pay as little as possible. Recently, Karlin, Kempe and Tamir introduced a new definition of frugality ratio for this setting. Informally, the frugality ratio is the ratio of the

Edith Elkind; Leslie Ann Goldberg; Paul W. Goldberg

2007-01-01

252

Sex ratios and sexual selection in socially monogamous zebra finches  

Microsoft Academic Search

An experiment was performed in which adult sex ratios of zebra finches, Taeniopygyia guttata castanotis, were varied to test possible effects of adult population sex ratios on sexual selection intensity and mating system dynamics in species with biparental care. The possibility that sex ratio influences the success of social mating patterns (leading to polygyny when males are rare and polyandry

Nancy Tyler Burley; Jennifer Devlin Calkins

1999-01-01

253

The mass ratio in spectroscopic binaries  

NASA Astrophysics Data System (ADS)

The process of formation of binary and multiple stars is not yet fully understood. Possibilities range from simultaneous processes of condensation from the primeval nebula, to isolated star formation and eventual capture to form a double system. Models exist that predict success probabilities for each theoretical process, and comparison with observational data is crucial. Spectroscopic binaries are specially suited to be used as observational data, since several biases that can arise from general catalogues of binary stars can be avoided, including dominance of systems with large separations between components. A very important parameter in these studies is the mass ratio, the quocient of the masses of primary and secundary members. The histogram of mass ratios provides crucial information to models of binary formation, linked to condensation processes and evolutionaty rates.In this case, spectroscopic binaries can be chosen as the observational sample, provided that the spectrum of the primary is from a non-evolved, main-sequence star,whose mass can be derived reliably from its spectral type. Defining an adequate limiting magnitude (6.5), one avoids bias from eclipsing systems with high inclinations, since nearly all systems up to 6.5 mag were detected. In this paper, a critical review is presented of the existing methods for deriving the distribution of the mass ratios from spectroscopic binary orbital data. After showing the incorrectness of some results published in the litterature, the available data (Batten's 8th Catalogue, 1989) is discussed. Simulations for several distributions of mass ratios (constant, quadratic, etc) are performed. It is shown that the existing data permits only to assert that the spectroscopic binaries with small mass ratios (q < 0.4) are more frequent that those with large mass ratios (q = 0.9 to 1.0).

Ducati, J. R.; Penteado, E. M.; Turcati, R.

2003-08-01

254

Effects of Al2O3 and CaO/SiO2 Ratio on Phase Equilbria in the ZnO-"FeO"-Al2O3-CaO-SiO2 System in Equilibrium with Metallic Iron  

NASA Astrophysics Data System (ADS)

The phase equilibria and liquidus temperatures in the ZnO-"FeO"-Al2O3-CaO-SiO2 system in equilibrium with metallic iron have been determined experimentally in the temperature range 1383 K to 1573 K (1150 °C to 1300 °C). The experimental conditions were selected to characterize lead blast furnace and imperial smelting furnace slags. The results are presented in a form of pseudoternary sections ZnO-"FeO"-(Al2O3 + CaO + SiO2) with fixed CaO/SiO2 and (CaO + SiO2)/Al2O3 ratios. It was found that wustite and spinel are the major primary phases in the composition range investigated. Effects of Al2O3 concentration as well as the CaO/SiO2 ratio on the primary phase field, the liquidus temperature, and the partitioning of ZnO between liquid and solid phases have been discussed for zinc-containing slags.

Zhao, Baojun; Hayes, Peter C.; Jak, Evgueni

2011-02-01

255

Effects of Al2O3 and CaO/SiO2 Ratio on Phase Equilbria in the ZnO-``FeO''-Al2O3-CaO-SiO2 System in Equilibrium with Metallic Iron  

NASA Astrophysics Data System (ADS)

The phase equilibria and liquidus temperatures in the ZnO-“FeO”-Al2O3-CaO-SiO2 system in equilibrium with metallic iron have been determined experimentally in the temperature range 1383 K to 1573 K (1150 °C to 1300 °C). The experimental conditions were selected to characterize lead blast furnace and imperial smelting furnace slags. The results are presented in a form of pseudoternary sections ZnO-“FeO”-(Al2O3 + CaO + SiO2) with fixed CaO/SiO2 and (CaO + SiO2)/Al2O3 ratios. It was found that wustite and spinel are the major primary phases in the composition range investigated. Effects of Al2O3 concentration as well as the CaO/SiO2 ratio on the primary phase field, the liquidus temperature, and the partitioning of ZnO between liquid and solid phases have been discussed for zinc-containing slags.

Zhao, Baojun; Hayes, Peter C.; Jak, Evgueni

2010-11-01

256

Progressive Ratio Schedules of Reinforcement  

PubMed Central

Pigeons’ pecks produced grain under progressive ratio (PR) schedules, whose response requirements increased systematically within sessions. Experiment 1 compared arithmetic (AP) and geometric (GP) progressions. Response rates increased as a function of the component ratio requirement, then decreased linearly (AP) or asymptotically (GP). Experiment 2 found the linear decrease in AP rates to be relatively independent of step size. Experiment 3 showed pausing to be controlled by the prior component length, which predicted the differences between PR and regressive ratio schedules found in Experiment 4. When the longest component ratios were signaled by different key colors, rates at moderate ratios increased, demonstrating control by forthcoming context. Models for response rate and pause duration described performance on AP schedules; GP schedules required an additional parameter representing the contextual reinforcement.

Killeen, Peter R.; Posadas-Sanchez, Diana; Johansen, Espen Borga; Thrailkill, Eric A.

2009-01-01

257

Poisson'S Ratio in Orthotropic Materials.  

National Technical Information Service (NTIS)

Poisson's ratio is frequently measured in uniaxial testing of orthotropic materials, and values in excess of unity are common for composites. In isotropic materials it is known that values larger than one half are thermodynamically inadmissible, for such ...

B. M. Lempriere

1968-01-01

258

Ardennes Fractional Exchange Ratio Research.  

National Technical Information Service (NTIS)

The US Army Concepts Analysis Agency (CAA) requires guidelines on use and computation of the combat measure of effectiveness (MOE) denote as the fractional exchange ratio (FER). The Ardennes Campaign Simulation Data Base (ACSDB) derived from historical ar...

W. Bauman

1997-01-01

259

Fixed-ratio punishment1  

PubMed Central

Responses were maintained by a variable-interval schedule of food reinforcement. At the same time, punishment was delivered following every nth response (fixed-ratio punishment). The introduction of fixed-ratio punishment produced an initial phase during which the emission of responses was positively accelerated between punishments. Eventually, the degree of positive acceleration was reduced and a uniform but reduced rate of responding emerged. Large changes in the over-all level of responding were produced by the intensity of punishment, the value of the punishment ratio, and the level of food deprivation. The uniformity of response rate between punishments was invariant in spite of these changes in over-all rate and contrary to some plausible a priori theoretical considerations. Fixed-ratio punishment also produced phenomena previously observed under continuous punishment: warm-up effect and a compensatory increase. This type of intermittent punishment produced less rapid and less complete suppression than did continuous punishment.

Azrin, N. H.; Holz, W. C.; Hake, D. F.

1963-01-01

260

Revisited nitrogen isotopic ratio in molecular clouds  

NASA Astrophysics Data System (ADS)

Fundamental for the understanding of nucleosynthesis processes as well as galactic and solar system evolution, the nitrogen isotope ratio in the galaxy has long been a puzzle. Particularly, meteorites, comets and IDPs show a strong enhancement of the 15N isotope compared to values estimated from molecular clouds, which casts doubts on the pristine nature of the cometary and meteoritic material. Due to high optical depths of the main nitrogen carriers, direct measurement of [14N/15N] is difficult. To date only a few global studies of the nitrogen isotope ratio in dense molecular clouds exist, which employ indirect methods to estimate this ratio. We revisit the nitrogen isotope ratio in dense molecular clouds using two nitrogen carriers, HNC and CN, and several methods. The J=1-0 and 3-2 transitions of HNC at 90 and 271 GHz, and H15NC at 88 and 266 GHz were observed at the Arizona Radio Observatory (ARO) 12m and SMT telescopes, toward the clouds SgrB2, W31, G34.3, W51M, M17-SW, DR-21, Orion A, W3(OH), NGC7538 and S156, located at various galactic distances from the Galactic Center. HNC being optically thick, its abundance was estimated using known [12C/13C] ratios, as well as radiative transfer modeling using the freely available code RADEX. Finally, the N=1-0 transition of CN and C15N at 113 and 110 GHz were also recorded at the 12m telescope. The last and most direct estimation method makes use of the intensities of CN hyperfines to estimate an optical depth and abundance for the main isotope. Results seem to indicate a [14N/15N] ratio of about ˜ 100-350, lower than previously reported, and more in line with cometary or meteoritic values.

Adande, G.; Ziurys, L.

2011-05-01

261

Isotopic ratios in planetary atmospheres.  

PubMed

Recent progress on measurements of isotopic ratios in planetary or satellite atmospheres include measurements of the D/H ratio in the methane of Uranus, Neptune and Titan and in the water of Mars and Venus. Implications of these measurements on our understanding of the formation and evolution of the planets and satellite are discussed. Our current knowledge of the carbon, nitrogen and oxygen isotopic ratios in the atmospheres of these planets, as well as on Jupiter and Saturn, is also reviewed. We finally show what progress can be expected in the very near future due to some new ground-based instrumentation particularly well suited to such studies, and to forthcoming space missions. PMID:11539257

de Bergh, C

1995-03-01

262

Surface to Volume Ratio Activity  

NSDL National Science Digital Library

By the National Nanotechnology Infrastructure Network, this two-part laboratory activity was designed to complement any chemistry unit on catalysts to "help students understand how nanoparticles may be more effective catalysts by investigating how the surface area-to-volume ratio of a substance is affected as its shape changes." On this site, educators can find both the teacher and student instructions for preparing and presenting the laboratory with objectives, time periods, materials, procedures, example answers, and much more. It is a ready-to-use lesson to help students understand catalysts and surface to volume ratio at molecular and atomic levels.

2009-01-14

263

Thin solar concentrator with high concentration ratio  

NASA Astrophysics Data System (ADS)

Solar concentrators are often used in conjunction with III-V multi-junction solar cells for cost reduction and efficiency improvement purposes. High flux concentration ratio, high optical efficiency and high manufacture tolerance are the key features required for a successful solar concentrator design. This paper describes a novel solar concentrator that combines the concepts, and thus the advantages, of both the refractive type ad reflective type. The proposed concentrator design adopts the Etendue-cascading concept that allows the light beams from all the concentric annular entrance pupils to be collected and transferred to the solar cell with minimal loss. This concept enables the system to perform near its Etendue-Limit and have a high concentration ratio simultaneously. Thereby reducing the costs of solar cells and therefor achieves a better the per watts cost. The concentrator demonstrated has a thing aspect ratio of 0.19 with a zero back focal distance. The numerical aperture at the solar cell immersed inside the dielectric concentrator is as high as 1.33 achieving a unprecedented high optical concentration ratio design.

Lin, Jhe-Syuan; Liang, Chao-Wen

2013-09-01

264

Fission Product Ratios as Treaty Monitoring Discriminants  

SciTech Connect

The International Monitoring System (IMS) of the Comprehensive Test Ban Treaty Organization (CTBTO) is currently under construction. The IMS is intended for monitoring of nuclear explosions. The radionuclide branch of the IMS monitors the atmosphere for short-lived radioisotopes indicative of a nuclear weapon test, and includes field collection and measurement stations, as well as laboratories to provide reanalysis of the most important samples and a quality control function. The Pacific Northwest National Laboratory in Richland, Washington hosts the United States IMS laboratory, with the designation “RL16.” Since acute reactor containment failures and chronic reactor leakage may also produce similar isotopes, it is tempting to compute ratios of detected isotopes to determine the relevance of an event to the treaty or agreement in question. In this paper we will note several shortcomings of simple isotopic ratios: (1) fractionation of different chemical species, (2) difficulty in comparing isotopes within a single element, (3) the effect of unknown decay times. While these shortcomings will be shown in the light of an aerosol sample, several of the problems extend to xenon isotopic ratios. The result of the difficulties listed above is that considerable human expertise will be required to convert a simple mathematical ratio into a criterion which will reliably categorize an event as ‘reactor’ or ‘weapon’.

Miley, Harry S.; Bowyer, Ted W.; Greenwood, Lawrence R.; Arthur, Richard J.

2008-05-15

265

The Prigogine-Defay ratio revisited.  

PubMed

One of the basic characteristics of the glass transition, the Prigogine-Defay ratio, connecting jumps of the thermal expansion coefficient, isothermal compressibility, and isobaric specific heat capacity in vitrification is rederived in the framework of the thermodynamics of irreversible processes employing the order-parameter concept introduced by de Donder and van Rysselberghe [Thermodynamic Theory of Affinity (Stanford University Press, Stanford, 1936)]. In our analysis, glass-forming liquids and glasses are described by only one structural order parameter. However, in contrast to previous approaches to the derivation of this ratio, the process of vitrification is treated not in terms of Simon's simplified model [Z. Anorg. Allg. Chem. 203, 219 (1931)] as a freezing-in process proceeding at some sharp temperature, the glass transition temperature T(g), but in some finite temperature interval accounting appropriately for the nonequilibrium character of vitrifying systems in this temperature range. As the result of the theoretical analysis, we find, in particular, that the Prigogine-Defay ratio generally has to have values larger than 1 for vitrification in cooling processes. Quantitative estimates of the Prigogine-Defay ratio are given utilizing a mean-field lattice-hole model of glass-forming melts. Some further consequences are derived concerning the behavior of thermodynamic coefficients, in particular, of Young's modulus in vitrification. The theoretical results are found to be in good agreement with experimental data. PMID:17115769

Schmelzer, Jürn W P; Gutzow, Ivan

2006-11-14

266

Energy Balance Bowen Ratio Station (EBBR) Handbook  

SciTech Connect

The energy balance Bowen ratio (EBBR) system produces 30-minute estimates of the vertical fluxes of sensible and latent heat at the local surface. Flux estimates are calculated from observations of net radiation, soil surface heat flux, and the vertical gradients of temperature and relative humidity (RH). Meteorological data collected by the EBBR are used to calculate bulk aerodynamic fluxes, which are used in the Bulk Aerodynamic Technique (BA) EBBR value-added product (VAP) to replace sunrise and sunset spikes in the flux data. A unique aspect of the system is the automatic exchange mechanism (AEM), which helps to reduce errors from instrument offset drift.

Cook, DR

2011-02-23

267

Air/fuel ratio detector  

SciTech Connect

This patent describes a method for detecting the air/fuel ratio of exhaust gas with a detector comprising an electrochemical cell sensor element and an oxygen pump element. Each element is in the form of an oxygen-ion-conductive solid electrolyte having a porous electrode formed on both sides thereof. The electrochemical cell sensor element being disposed to face the pump element with a small gap therebetween, exposed to the exhaust gas and an air compartment which is open to the atmosphere being formed on that side of the pump element which is opposite to the small gap. An electric current is caused to flow through the oxygen pump element so that oxygen is pumped into the small gap from the air compartment or in the opposite direction, thereby producing an electromotive force in the sensor element. The electromotive force and the current flowing through the pump element is used as a basis for detecting the air/fuel ratio of the exhaust gas. The improvement described here is wherein a sufficient amount of current to pump oxygen from the air compartment into the small gap is caused to flow through the oxygen pump element so as to produce an abrupt change in the electromotive force of the sensor element at a stoichiometric air/fuel ratio. The electromotive force of the sensor element is used to determine whether a present air/fuel ratio is in the fuel-rich or fuel-lean region.

Yamada, T.; Hirate, S.

1986-10-07

268

Declustering Using Golden Ratio Sequences  

Microsoft Academic Search

In this paper we propose a new data declustering scheme for range queries. Our schemeis based on Golden Ratio Sequences (GRS), which have found applications in broadcast disks,hashing, packet routing, etc. We show by analysis and simulation that GRS is nearly the bestpossible scheme for 2-dimensional range queries. Specifically, it is the best possible scheme whenthe number of disks (M

Randeep Bhatia; Rakesh K. Sinha; Chung-min Chen

2000-01-01

269

Surface Area to Volume Ratio  

NSDL National Science Digital Library

This page contains two documents explaining surface area to volume ratio. The topic is covered at an advanced level in relation to nanotechnology and requires background knowledge in geometry, algebra, and linear and non-linear unit conversions. A powerpoint with illustrations and instructor guide (available as both a Microsoft Word Document and PDF) containing activities are included to aid in teaching this subject.

2012-10-16

270

Empirical Likelihood Ratio Confidence Regions  

Microsoft Academic Search

An empirical likelihood ratio function is defined and used to obtain confidence regions for vector valued statistical functionals. The result is a nonparametric version of Wilks' theorem and a multivariate generalization of work by Owen. Cornish-Fisher expansions show that the empirical likelihood intervals for a one dimensional mean are less adversely affected by skewness than are those based on Student's

Art Owen

1990-01-01

271

A Ratio Explanation for Evolution.  

ERIC Educational Resources Information Center

|Describes hands-on physical anthropology activities for teaching students about evolution. Using evidence found in hominid skulls, students conduct investigations that involve calculating ratios. Eight full-page photographs of skulls from the program Stones and Bones are included. (PR)|

Riss, Pam Helfers

1993-01-01

272

Factors affecting selected reciprocal muscle group ratios in preadolescents.  

PubMed

This study examines the influence of limb velocity and lateral dominance on the relationship between the knee flexors and extensors. Thirty preadolescents, 18 male and 12 female, performed a series of reciprocal knee flexion-extension movements on the Cybex II isokinetic system. The tests were performed at a range of selected velocities and on both dominant and nondominant limbs. The agonist-antagonist ratios considered were the peak torque ratios, the torque ratio produced at specific angles, and the ratio comparing the total work performed by the hamstrings with that of the quadriceps. The results showed that an increased limb velocity produces a significant increase in the peak torque and work ratios (P less than 0.05), limb velocity has no significant effect on the torque ratio produced at 30 degrees and 60 degrees in the preadolescents, and lower limb lateral dominance has no significant effect on the three ratios examined. PMID:3557782

Burnie, J

1987-02-01

273

Queen Control of Sex Ratio in Fire Ants  

Microsoft Academic Search

The haplodiploid sex-determination system of ants gives rise to conflict between queens and workers over colony sex ratios, and the female-biased allocation ratios seen in many species suggest that workers often prevail in this conflict. We exchanged queens between male- and female-specialist colonies of the fire ant Solenopsis invicta. These exchanges quickly reversed the sex-ratio biases of adopting colonies. The

L. Passera; S. Aron; E. L. Vargo; L. Keller

2001-01-01

274

The glenohumeral offset ratio: A radiographic study.  

PubMed

A systematic method of component selection for total shoulder arthroplasty is needed. The method must take into account the soft-tissue constraints of a degenerative joint and optimize joint biomechanics by placing the joint line in the best possible position. The purpose of our study was to determine radiographically the normal glenohumeral joint line position based on a ratio of distances between the joint line and fixed landmarks on the humerus and scapula. We studied modified anteroposterior radiographs of the glenohumeral joint in 86 volunteers (51 men and 35 women; ages ranging from 21 to 47 years). Two measurements were made on each radiograph: (1) the perpendicular distance from the most medial portion of the glenoid to the inferior base of the coracoid process at its attachment to the scapular blade, and (2) the perpendicular distance from the midline of the humeral shaft to the most medial point on the humeral head. The joint line position was described as the ratio of the glenoid measurement to the sum of the two measurements (i.e., the glenohumeral offset ratio). The validity and reliability of glenoid offset measurements were determined by comparing radiographic and anatomic measurements of glenoid offset in cadaveric human scapulae. Radiographs were made with rotational error to determine its effects on the measurement of humeral offset. Humeral offsets and glenoid thicknesses of five different total shoulder systems were then determined from template overlays. The mean glenohumeral offset ratio was 0.31 (range 0.18 to 0.39). We detected no significant difference in the ratio between men and women volunteers. There was close agreement between radiographie and direct (anatomic) measurements of glenoid offset in cadaveric scapulae. Values for humeral offset were not significantly affected by radiographic rotational error. The evidence indicates that a fairly constant glenohumeral offset ratio in normal shoulders can be reliably calculated from a single radiograph. In addition to the prosthesis specifications, we suggest that the glenohumeral offset ratio is a potentially useful preoperative planning tool for total shoulder arthroplasty. PMID:22959406

Jacobson, S R; Mallon, W J

2009-02-19

275

Models of Ratio Schedule Performance  

PubMed Central

Predictions of P. R. Killeen's (1994) mathematical principles of reinforcement were tested for responding on ratio reinforcement schedules. The type of response key, the number of sessions per condition, and first vs. second half of a session had negligible effects on responding. Longer reinforcer durations and larger grain types engeridered more responding, affecting primarily the parameter a (specific activation). Key pecking was faster than treadle pressing, affecting primarily the parameter ? (response time). Longer intertrial intervals led to higher overall response rates and shorter postreinforcement pauses and higher running rates, and ruled out some competing explanations. The treadle data required a distinction between the energetic requirements and rate-limiting properties of extended responses. The theory was extended to predict pause durations and run rates on ratio schedules.

Bizo, Lewis A.; Killeen, Peter R.

2008-01-01

276

Fluorescence intensity ratio stereoscopic transform.  

PubMed

A novel approach to 3-D information processing of 2-D cell images is presented, called fluorescence intensity ratio stereoscopic transform (FIRST). Here, we describe its basic principle of image processing and show the results for the ratio of total internal reflection fluorescence (TIRF) to fluorescence intensity. A simple, intuitive transform algorithm would help us to easily obtain a clear stereoscopic image from two 2-D cell images with different fluorescence intensity. For this purpose, nonlinear evanescent-field (EF) imaging of cell-membrane surface and its intracellular structures by using on-chip grating coupler is achieved. This method enabled us to obtain cell images with different signal-to-background ratio and resolution under microfluidic environments. Specifically, we manipulated optic pathway to partially illuminate microscale objects within the microfluidic channel. These findings imply this method will enable selectively to detect optical signals of biomolecular interaction within the cell membrane in a controlled manner. Furthermore, we believe this approach will help to develop an optofluidic sensor for individually detecting dynamic behaviors of intracellular molecules in living cells under microfluidic cell culture environments. PMID:22121719

Yun, Hoyoung; Min, Junggi; Bang, Hyunwoo; Han, Dong-Chul; Lee, Soon-Geul; Lee, Won Gu

2011-07-01

277

Modeling the distribution of isotopic ratios in geochemical reservoirs  

Microsoft Academic Search

We present an extension of the conventional geochemical reservoir model for the evolution of the Earth’s crust–mantle system in which we calculate not only the mean isotopic ratios, but also the distribution of those ratios within the reservoirs. Owing to low chemical diffusion rates, subreservoirs that are created by mass transport into and out of the mantle effectively exist as

James B. Kellogg; Stein B. Jacobsen; Richard J. O’Connell

2002-01-01

278

Combined measurements of a UV mini MAX-DOAS system and a TX for retrieval of ambient trace gas mixing ratio: Comparisons with combined RTM and MAX-DOAS methods  

Microsoft Academic Search

A measurement method combining multi-axis differential optical absorption spectroscopy (MAX-DOAS) and a transmissometer (TX) is introduced as a means of retrieving surface trace gas mixing ratios in ambient air. The combined measurement method was utilized to derive surface NO2 mixing ratios from 27 March to 11 May 2007 in Seoul, Korea. To convert the differential slant column density (DSCD) to

Hanlim Lee; Jaeyong Ryu; Jhoon Kim; Youngmin Noh; Younghun Yoon

2011-01-01

279

Development and Application of the Detector-Response-Ratio Method of Identification for a Dual-Detection System. Application of GC with Electron-Capture and Nitrogen–Phosphorus Detection to the Determination of Pesticides in Aqueous Matrices  

Microsoft Academic Search

Dual detection has already been used to analyse organic contaminants in several matrices and the potential use of this technique\\u000a for compound identification using the detector-response ratio (DRR) for two detectors has been reported. In this study DRR\\u000a was redefined in terms of analyte concentration. The ratio was applied to compounds with both positive and negative responses\\u000a fitting linear or

E. Jover; A. Gómez-Gutiérrez; J. M. Bayona

2007-01-01

280

Using Ratio Analysis to Evaluate Financial Performance.  

ERIC Educational Resources Information Center

|The ways in which ratio analysis can help in long-range planning, budgeting, and asset management to strengthen financial performance and help avoid financial difficulties are explained. Types of ratios considered include balance sheet ratios, net operating ratios, and contribution and demand ratios. (MSE)|

Minter, John; And Others

1982-01-01

281

Envera Variable Compression Ratio Engine  

SciTech Connect

Aggressive engine downsizing, variable compression ratio and use of the Atkinson cycle are being combined to improve fuel economy by up to 40 percent relative to port fuel injected gasoline engines, while maintaining full engine power. Approach Engine downsizing is viewed by US and foreign automobile manufacturers as one of the best options for improving fuel economy. While this strategy has already demonstrated a degree of success, downsizing and fuel economy gains are currently limited. With new variable compression ratio technology however, the degree of engine downsizing and fuel economy improvement can be greatly increased. A small variable compression ratio (VCR) engine has the potential to return significantly higher vehicle fuel economy while also providing high power. Affordability and potential for near term commercialization are key attributes of the Envera VCR engine. VCR Technology To meet torque and power requirements, a smaller engine needs to do more work per stroke. This is typically accomplished by boosting the incoming charge with either a turbo or supercharger so that more energy is present in the cylinder per stroke to do the work. With current production engines the degree of engine boosting (which correlates to downsizing) is limited by detonation (combustion knock) at high boost levels. Additionally, the turbo or supercharger needs to be responsive and efficient while providing the needed boost. VCR technology eliminates the limitation of engine knock at high load levels by reducing compression ratio to {approx}9:1 (or whatever level is appropriate) when high boost pressures are needed. By reducing the compression ratio during high load demand periods there is increased volume in the cylinder at top dead center (TDC) which allows more charge (or energy) to be present in the cylinder without increasing the peak pressure. Cylinder pressure is thus kept below the level at which the engine would begin to knock. When loads on the engine are low the compression ratio can be raised (to as much as 18:1) providing high engine efficiency. It is important to recognize that for a well designed VCR engine cylinder pressure does not need to be higher than found in current production turbocharged engines. As such, there is no need for a stronger crankcase, bearings and other load bearing parts within the VCR engine. The Envera VCR mechanism uses an eccentric carrier approach to adjust engine compression ratio. The crankshaft main bearings are mounted in this eccentric carrier or 'crankshaft cradle' and pivoting the eccentric carrier 30 degrees adjusts compression ratio from 9:1 to 18:1. The eccentric carrier is made up of a casting that provides rigid support for the main bearings, and removable upper bearing caps. Oil feed to the main bearings transits through the bearing cap fastener sockets. The eccentric carrier design was chosen for its low cost and rigid support of the main bearings. A control shaft and connecting links are used to pivot the eccentric carrier. The control shaft mechanism features compression ratio lock-up at minimum and maximum compression ratio settings. The control shaft method of pivoting the eccentric carrier was selected due to its lock-up capability. The control shaft can be rotated by a hydraulic actuator or an electric motor. The engine shown in Figures 3 and 4 has a hydraulic actuator that was developed under the current program. In-line 4-cylinder engines are significantly less expensive than V engines because an entire cylinder head can be eliminated. The cost savings from eliminating cylinders and an entire cylinder head will notably offset the added cost of the VCR and supercharging. Replacing V6 and V8 engines with in-line VCR 4-cylinder engines will provide high fuel economy at low cost. Numerous enabling technologies exist which have the potential to increase engine efficiency. The greatest efficiency gains are realized when the right combination of advanced and new technologies are packaged together to provide the greatest gains at the least cost. Aggressive engine downsiz

Charles Mendler

2011-03-15

282

Measurement of tau branching ratios  

SciTech Connect

We have measured the branching ratios for several tau decay modes. We use e/sup +/e/sup -/..-->..tau/sup +/tau/sup -/ events accumulated with the TPC/Two-Gamma facility at the SLAC e/sup +/e/sup -/ storage ring PEP. The data correspond to an integrated luminosity of 77 pb/sup -1/ at a center-of-mass energy of 29 GeV. The one- and three-charged-particle inclusive branching ratios of the tau decay are measured to be B/sub 1/ = (84.7 +- 1.0)% and B/sub 3/ = (15.1 +- 1.0)%, where B/sub 1/+B/sub 3/ is constrained to be 99.85%. The branching ratios of the two leptonic decay modes are B(tau/sup -/..-->..e/sup -/ nu-bar/sub e/..nu../sub tau/) = (18.4 +- 1.6)% and B(tau/sup -/..--> mu../sup -/ nu-bar/sub ..mu../..nu../sub tau/) = (17.7 +- 1.4)%. If we then assume lepton universality, we obtain B(tau/sup -/..-->..e/sup -/ nu-bar/sub e/..nu../sub tau/) = (18.3 +- 0.9)% and B(tau/sup -/..--> mu../sup -/ nu-bar/sub ..mu../..nu../sub tau/) = (17.8 +- 0.9)%. We measure the Cabibbo-allowed semihadronic decay mode B(tau/sup -/..--> pi../sup -/+neutral particles) = (47.0 +- 1.5)%, and the Cabibbo-suppressed tau decay mode B(tau/sup -/..-->..K/sup -/+neutral particles) = (1.6 +- 0.4)%. By looking for associated photons, we find B(tau/sup -/..-->..K/sup -/..pi../sup 0/+neutral particles) to be (1.2 +- 0.6)%.

Aihara, H.; Alston-Garnjost, M.; Avery, R.E.; Bakken, J.A.; Barbaro-Galtieri, A.; Barker, A.R.; Barnes, A.V.; Barnett, B.A.; Barnett, B.A.; Bauer, D.A.; and others

1987-03-01

283

Thermosolutal Convection in High-Aspect-Ratio Enclosures.  

National Technical Information Service (NTIS)

Convection in high-aspect-ratio rectangular enclosures with combined horizontal temperature and concentration gradients is studied experimentally. An electrochemical system is employed to impose the concentration gradients. The solutal buoyancy force eith...

L. W. Wang C. T. Chen

1988-01-01

284

Activity ratios of thorium daughters in vivo  

SciTech Connect

A computerized method of least squares has been used to analyze the /sup 228/Ac and /sup 212/Pb-/sup 212/Bi and daughter ..gamma..-ray spectra obtained in vivo from 133 former workers at a thorium refinery. In addition, the exhalation rate of /sup 220/Rn was determined for each subject and expressed as pCi of emanating /sup 224/Ra. This value was added to the /sup 212/Pb value determined from the ..gamma..-ray measurements to obtain the total /sup 224/Ra present, and the ratio of /sup 224/Ra to /sup 228/Ac was calculated. Values of the ratio ranged from 0.52 +- 0.32 to 2.1 +- 1.7, with a weighted mean of 0.92 +- 0.17. However, it appears that the ratio observed in a given case is characteristic for that case alone; the computed mean value may not be meaningful. The least squares fitting procedure and the overall calibration of the counting system were validated by measurements of /sup 224/Ra in the lungs of one subject postmortem, compared with results obtained from the same subject in vivo. 6 references, 5 figures.

Toohey, R.E.; Rundo, J.; Sha, J.Y.; Essling, M.A.; Pedersen, J.C.; Slane, J.M.

1984-01-01

285

Reconstructing bulk isotope ratios from compound-specific isotope ratios.  

PubMed

Carbon isotope analysis by bulk elemental analysis coupled with isotope ratio mass spectrometry has been the mainstay of delta(13)C analyses both at natural abundance and in tracer studies. More recently, compound-specific isotope analysis (CSIA) has become established, whereby organic constituents are separated online by gas or liquid chromatography before oxidation and analysis of CO(2) for constituent delta(13)C. Theoretically, there should be concordance between bulk delta(13)C measurements and carbon-weighted delta(13)C measurements of carbon-containing constituents. To test the concordance between the bulk and CSIA, fish oil was chosen because the majority of carbon in fish oil is in the triacylglycerol form and approximately 95% of this carbon is amenable to CSIA in the form of fatty acids. Bulk isotope analysis was carried out on aliquots of oil extracted from 55 fish samples and delta(13)C values were obtained. Free fatty acids (FFAs) were produced from the oil samples by saponification and derivatised to fatty acid methyl esters (FAMEs) for CSIA by gas chromatography/combustion/isotope ratio mass spectrometry. A known amount of an internal standard (C15:0 FAME) was added to allow analyte quantitation. This internal standard was also isotopically calibrated in both its FFA (delta(13)C = -34.30 per thousand) and FAME (delta(13)C = -34.94 per thousand) form. This allowed reporting of FFA delta(13)C from measured FAME delta(13)C values. The bulk delta(13)C was reconstructed from CSIA data based on each FFA delta(13)C and the relative amount of CO(2) produced by each analyte. The measured bulk mean delta(13)C (SD) was -23.75 per thousand (1.57 per thousand) compared with the reconstructed bulk mean delta(13)C of -23.76 (1.44 per thousand) from CSIA and was not significantly different. Further analysis of the data by the Bland-Altman method did not show particular bias in the data relative to the magnitude of the measurement. Good agreement between the methods was observed with the mean difference between methods (range) of 0.01 per thousand (-1.50 to 1.30). PMID:20499325

Morrison, Douglas J; Cooper, Karen; Preston, Tom

2010-06-30

286

Newborn Brain: Body weight ratios.  

PubMed

Newborn brain:body weight ratios are generally considered to be constant in man. In autopsy studies many factors influence the measured weight of the brain, and therefore the conclusions based on such observations, including the gestational age of the material, the presence or absence of intrauterine growth retardation, and the cause of death. In this study these influences have been eliminated by careful selection of normally grown fullterm newborns not subject to the factors influencing brain weight. Using double logarithmic plots, brain size in fullterm newborns is found to be related to the 0.64 power of birth weight. There is a negative correlation between relative brain size and increasing fullterm birth size in man. PMID:1258985

Jordaan, H V

1976-03-01

287

Variable ratio regenerative braking device  

DOEpatents

Disclosed is a regenerative braking device (10) for an automotive vehicle. The device includes an energy storage assembly (12) having a plurality of rubber rollers (26, 28) mounted for rotation between an input shaft (36) and an output shaft (42), clutches (38, 46) and brakes (40, 48) associated with each shaft, and a continuously variable transmission (22) connectable to a vehicle drivetrain and to the input and output shafts by the respective clutches. The rubber rollers are torsionally stressed to accumulate energy from the vehicle when the input shaft is clutched to the transmission while the brake on the output shaft is applied, and are torsionally relaxed to deliver energy to the vehicle when the output shaft is clutched to the transmission while the brake on the input shaft is applied. The transmission ratio is varied to control the rate of energy accumulation and delivery for a given rotational speed of the vehicle drivetrain.

Hoppie, Lyle O. (Birmingham, MI)

1981-12-15

288

Ratio cut partitioning for hierarchical designs  

Microsoft Academic Search

Circuit partitioning for hierarchical VLSI design is addressed. A partitioning approach called ratio cut is proposed. It is demonstrated that the ratio cut algorithm can locate the clustering structures in the circuit. Finding the optimal ratio cut is NP-complete. However, in certain cases the ratio cut can be solved by linear programming techniques via the multicommodity flow formulation. Also proposed

Yen-chuen Wei; Chung-kuan Cheng

1991-01-01

289

Isokinetic Hamstrings: Quadriceps Ratios in Intercollegiate Athletes.  

ERIC Educational Resources Information Center

|Compared the differences in the concentric hamstrings to quadriceps (H:Q) ratio among athletes in different sports at three velocities. Measurement of H:Q ratio of both knees among male and female college athletes indicated that the H:Q ratio increased as velocity increased. No differences existed for the H:Q ratio for sport or side of body. (SM)|

Rosene, John M.; Fogarty, Tracey D.; Mahaffey, Brian L.

2001-01-01

290

Temperature-controlled electrothermal atomization-atomic absorption spectrometry using a pyrometric feedback system in conjunction with a background monitoring device  

NASA Astrophysics Data System (ADS)

The construction of a temperature-controlled feedback system for electrothermal atomization-atomic absorption spectrometry (ETA-AAS) using an optical pyrometer applied to the atomization stage is described. The system was used in conjunction with a fast-response background monitoring device. The heating rate of the furnace amounted to 1400° s -1 with a reproducibility better than 1%. The precision of the temperature control at a steady state temperature of 2000°C was 0.1%. The analytical improvements offered by the present system have been demonstrated by the determination of cadmium and lead in blood and finally by the determination of lead in serum. Both the sensitivity and the precision of the method have been improved. The accuracy of the method was checked by determining the lead content for a number of scrum samples both by ETA-AAS and differential pulse anodic stripping voltametry (DPASV) and proved to be satisfactory.

Van Deijck, W.; Roelofsen, A. M.; Pieters, H. J.; Herber, R. F. M.

291

Isotopic ratios in giant planets  

NASA Astrophysics Data System (ADS)

The accuracy of spectrometric measurements of isotopic ratios in giant planets, and implications on the formation of giant planets are discussed. Derivations of D/H in Jupiter and Saturn form CH3D conflict with derivations from HD. Uncertainties in the interpretation come from the difficulty in estimating the fractionation factor between CH3D and CH4, and from scattering effects in the radiative transfer within HD and H2 absorption lines. However, deuterium abundance in the primordial solar nebula 4.6 billion yr ago can be estimated. Data suggest that D/H is enhanced in Uranus compared to Jupiter and Saturn, in agreement with a scenario of inhomogeneous formation of giant planets. The C12/C13 value in Jupiter from Voyager measurements suggests a value significantly higher than the terrestrial value, but conflicts with the value derived from ground based measurements, which agrees with the terrestrial value. The N14/N15 value is compatible with the terrestrial value.

Gautier, D.

292

Microhardness and Ca:P ratio of carious and Carisolv™ treated caries-affected dentine using an ultra-micro-indentation system and energy dispersive analysis of x-rays — A pilot study  

Microsoft Academic Search

Background: This study aimed to evaluate microhardness and chemical analysis of carious and caries-affected dentine. The hypothesis tested was that calcium:phosphorous (Ca:P) ratios correlate with microhardness values. Methods: Four carious human third molars were sectioned through the caries lesion in the mesio- distal longitudinal plane. One half of each lesion underwent carious dentine removal using Carisolv TM gel. The cut

R. Sakoolnamarka; MF Burrow; M. Swain; MJ Tyas

2005-01-01

293

Implications of Fast Reactor Transuranic Conversion Ratio  

SciTech Connect

Theoretically, the transuranic conversion ratio (CR), i.e. the transuranic production divided by transuranic destruction, in a fast reactor can range from near zero to about 1.9, which is the average neutron yield from Pu239 minus 1. In practice, the possible range will be somewhat less. We have studied the implications of transuranic conversion ratio of 0.0 to 1.7 using the fresh and discharge fuel compositions calculated elsewhere. The corresponding fissile breeding ratio ranges from 0.2 to 1.6. The cases below CR=1 (“burners”) do not have blankets; the cases above CR=1 (“breeders”) have breeding blankets. The burnup was allowed to float while holding the maximum fluence to the cladding constant. We graph the fuel burnup and composition change. As a function of transuranic conversion ratio, we calculate and graph the heat, gamma, and neutron emission of fresh fuel; whether the material is “attractive” for direct weapon use using published criteria; the uranium utilization and rate of consumption of natural uranium; and the long-term radiotoxicity after fuel discharge. For context, other cases and analyses are included, primarily once-through light water reactor (LWR) uranium oxide fuel at 51 MWth-day/kg-iHM burnup (UOX-51). For CR<1, the heat, gamma, and neutron emission increase as material is recycled. The uranium utilization is at or below 1%, just as it is in thermal reactors as both types of reactors require continuing fissile support. For CR>1, heat, gamma, and neutron emission decrease with recycling. The uranium utilization exceeds 1%, especially as all the transuranic elements are recycled. exceeds 1%, especially as all the transuranic elements are recycled. At the system equilibrium, heat and gamma vary by somewhat over an order of magnitude as a function of CR. Isotopes that dominate heat and gamma emission are scattered throughout the actinide chain, so the modest impact of CR is unsurprising. Neutron emitters are preferentially found among the higher actinides, so the neutron emission varies much stronger with CR, about three orders of magnitude.

Steven J. Piet; Edward A. Hoffman; Samuel E. Bays

2010-11-01

294

Sensitivity of stoichiometric ratios to temporal variability in streamflow  

Microsoft Academic Search

Increasing nutrient fluxes through river systems can contribute to the eutrophication and degradation of downstream aquatic ecosystems. The severity of these environmental impacts partially depends on the relative abundance of nutrients, which limit primary productivity and species composition. Stoichiometric ratios of nitrogen (N), phosphorus (P) and silicon (Si) in river systems are regulated by river discharge both directly, through the

S. D. Donner; D. N. Leong; T. P. Covino; R. S. Gabor; J. D. Drummond; X. Xu

2010-01-01

295

The Structure of High Strehl Ratio Point-Spread Functions  

Microsoft Academic Search

We describe the symmetries present in the point-spread function (PSF) of an optical system either located in space or corrected by an adaptive optics (AO) system to Strehl ratios of about 70% and higher. We present a formalism for expanding the PSF to arbitrary order in terms of powers of the Fourier transform of the residual phase error over an

Marshall D. Perrin; Anand Sivaramakrishnan; Russell B. Makidon; Ben R. Oppenheimer; James R. Graham

2003-01-01

296

The Paradox of Enrichment in Ratio-Dependent Ecoepidemic Models  

NASA Astrophysics Data System (ADS)

Recently experimental and theoretical ecologists have shown a renewed interest toward ratio-dependent models. Specific questions are raised by the occurrence of the paradox of enrichment in such systems. In the present study we investigate a recent eco-epidemiological model, with an underlying predator-prey demographics. Contrary to a widely accepted opinion, our extensive numerical simulations reveal that in the presence of infection the paradox of enrichment may also occur in ratio-dependent ecosystems.

Chatterjee, Samrat; Venturino, Ezio

2008-09-01

297

Combined measurements of a UV mini MAX-DOAS system and a TX for retrieval of ambient trace gas mixing ratio: Comparisons with combined RTM and MAX-DOAS methods  

NASA Astrophysics Data System (ADS)

A measurement method combining multi-axis differential optical absorption spectroscopy (MAX-DOAS) and a transmissometer (TX) is introduced as a means of retrieving surface trace gas mixing ratios in ambient air. The combined measurement method was utilized to derive surface NO 2 mixing ratios from 27 March to 11 May 2007 in Seoul, Korea. To convert the differential slant column density (DSCD) to the volume mixing ratio (VMR), the light path length (LPL) along the MAX-DOAS line of sight was derived using the light extinction coefficient and Ångstrom exponent data obtained by a TX and sunphotometer, respectively. Temporal variations of the NO 2 VMRs at the 0-1 km layer obtained from radiative transfer model (RTM) simulations coupled with MAX-DOAS data show similar patterns, but with reduced magnitudes, to the ground level data and those of the combined MAX-DOAS and TX measurements at 0.08 km. The NO 2 VMRs retrieved by the combined measurement were in agreement with those obtained from the RTM simulations coupled with MAX-DOAS data and the in-situ measurements within 40 and 50%, respectively. The coefficient of determination ( R 2 ) of 0.75 was obtained between the combined measurement data sets and those of the RTM simulations coupled with MAX-DOAS data whereas that between the combined measurement data sets and those of the in-situ measurements was 0.53. The coefficient of determination ( R 2 ) between the data sets derived from the RTM simulations coupled with MAX-DOAS data and those of the in-situ measurements was 0.67 with the scatter of the correlation within the 50% range.

Lee, Hanlim; Ryu, Jaeyong; Kim, Jhoon; Noh, Youngmin; Yoon, Younghun

2011-12-01

298

Addendum: Maximum Mass Ratio of AM CVn-Type Binary Systems and Maximum White Dwarf Mass in Ultra-Compact X-Ray Binaries, Published in Serb. Astron. J. No. 183 (2011), 63-69  

NASA Astrophysics Data System (ADS)

We recalculated the maximum white dwarf mass in ultra-compact X-ray binaries obtained in an earlier paper (Arbutina 2011), by taking the effects of super-Eddington accretion rate on the stability of mass transfer into account. It is found that, although the value formally remains the same (under the assumed approximations), for white dwarf masses M_2 ? 0.1 M_{{Ch}} mass ratios are extremely low, implying that the result for M_{max} is likely to have little if any practical relevance.

Arbutina, B.

2012-06-01

299

Medical Loss Ratio (MLR) (Affordable Care Act)  

MedlinePLUS

... Letters Regulations and Guidance Stakeholder Engagement Training Resources Medical Loss Ratio Many insurance companies spend a substantial ... services and quality improvement, also known as the Medical Loss Ratio (MLR). It also requires them to ...

300

Poisson`s ratio and crustal seismology  

SciTech Connect

This report discusses the use of Poisson`s ratio to place constraints on continental crustal composition. A summary of Poisson`s ratios for many common rock formations is also included with emphasis on igneous and metamorphic rock properties.

Christensen, N.I. [Purdue Univ., West Lafayette, IN (United States)

1996-02-10

301

Computation of Cold-Start Miss Ratios  

Microsoft Academic Search

Cold-start miss ratios are miss ratios that are measured with an initially empty first-level store. The values obtained depend on C, the first-level storage capacity, and on T, the number of references. These miss ratios, measured for various values of T, are useful in evaluating the effect of task switching on cache miss ratios when the cache capacity is C.

Malcolm C. Easton

1978-01-01

302

Using Lego Construction to Develop Ratio Understanding  

Microsoft Academic Search

This paper examines Year 7 students use and learning of ratio concepts while engaged in the technology practice of designing, constructing and evaluating simple machines, that used cogs and pulleys. It was found that most students made considerable progress in accounting for ratio concepts in their constructions and some constructed sophisticated machines and provided explicit and quantitative descriptions involving ratio

Stephen Norton

303

Ratio estimators in simple random sampling  

Microsoft Academic Search

This study proposes ratio estimators by adapting the estimators' type of Ray and Singh [J. Ind. Stat. Assoc. 19 (1981) 147] to traditional and the other ratio-type estimators in simple random sampling in literature. Theoretically, mean square error (MSE) equations of all proposed ratio estimators are obtained and compared with each other. By these comparisons the conditions, which make each

Cem Kadilar; Hulya Cingi

2004-01-01

304

Transformer ratio improvement for beam based plasma accelerators  

SciTech Connect

Increasing the transformer ratio of wakefield accelerating systems improves the viability of present novel accelerating schemes. The use of asymmetric bunches to improve the transformer ratio of beam based plasma systems has been proposed for some time[1, 2] but suffered from lack appropriate beam creation systems. Recently these impediments have been overcome [3, 4] and the ability now exists to create bunches with current profiles shaped to overcome the symmetric beam limit of R {<=} 2. We present here work towards experiments designed to measure the transformer ratio of such beams, including theoretical models and simulations using VORPAL (a 3D capable PIC code) [5]. Specifically we discuss projects to be carried out in the quasi-nonlinear regime [6] at the UCLA Neptune Laboratory and the Accelerator Test Facility at Brookhaven National Lab.

O'Shea, Brendan; Rosenzweig, James; Barber, Samuel; Fukasawa, Atsushi; Williams, Oliver; Muggli, Patric; Yakimenko, Vitaly; Kusche, Karl [University of California, Los Angeles, Department of Physics and Astronomy, Los Angeles, CA 90095 (United States); University of Southern California, Department of Electrical Engineering, Los Angeles, CA 90089 U.S.A. and Max-Planck-Institut fuer Physik, Foehringer Ring 6, 80805 Muenchen (Germany); Accelerator Test Facility, Brookhaven National Lab, Upton, NY, 11973 (United States)

2012-12-21

305

Skewed sex ratio at birth in India.  

PubMed

Scientists commonly use world average data on sex ratio at birth for India for want of dependable ones. Here an attempt is made to redress the problem to some extent. It is shown that this ratio has been high in India since the 1950s. The ratio has been strikingly high, even prior to the time of inception of prenatal sex identification technologies. The ratio shows a rising trend due to several biological reasons. In addition, it has been rising sharply for a couple of decades due to some socio-medical factors. The natural sex ratio at birth in India is noticeably higher than the world average. PMID:19758486

Seth, Swapan

2009-09-17

306

Dynamic Young's Moduli, Poisson's Ratios and Damping Ratios of Antrim Oil Shale.  

National Technical Information Service (NTIS)

Dynamic Young's Modulus, Poisson's Ratio and Damping Ratio in the horizontal and vertical directions have been measured on approximately 30 samples recovered from Well No. 201 and three samples from Well No. 107. Young's Moduli and Damping Ratios were det...

F. Somogyi

1980-01-01

307

What is the role of nodal ratio as a prognostic factor for gastric cancer nowadays? Comparison with new TNM staging system and analysis according to the number of resected nodes.  

PubMed

Nodal ratio (NR) has been demonstrated to be an important prognostic factor in patients with gastric cancer. The aim of this study is to evaluate the prognostic role of nodal ratio comparing it with the new TNM (2010) classification. One hundred forty-two patients were submitted to potentially curative gastrectomy for cancer. Patients with low performance status underwent D1.5 lymphadenectomy, whereas the other patients underwent D2-D2.5 lymphadenectomy. Nodal staging was classified according to 2010 International Union Against Cancer/American Joint Committee on Cancer classification. Kaplan-Meier method was used to evaluate survival, stratified for nodal classes and nodal status. Total gastrectomy was performed in 39 per cent of cases and distal gastrectomy in 61 per cent. Mean number of resected nodes was 25.5. Whereas N status was strictly related to the number of resected nodes, the NR was independent from the extension of the lymphadenectomy. Overall five-year survival was 81 per cent for N0 patients, 72 per cent for N1, and 26 and 23 per cent for N2 and N3, respectively. Patients with NR0 had 81 per cent five-year survival, whereas NR1 67 per cent, NR2 51 per cent, and NR3 22 per cent. NR seems to be a simple method to predict the prognosis of patients with gastric cancer; unlike N status, it is independent from the number of resected nodes, and therefore it is particularly useful in case of inadequate lymphadenectomy. PMID:23635583

Aurello, Paolo; Catracchia, Valeria; Petrucciani, Niccolò; D'Angelo, Francesco; Leonardo, Giacomo; Picchetto, Andrea; Antolino, Laura; Magistri, Paolo; Terrenato, Irene; Lauro, Augusto; Ramacciato, Giovanni

2013-05-01

308

Liquidus Temperatures of Cryolite Melts With Low Cryolite Ratio  

NASA Astrophysics Data System (ADS)

The effect of calcium fluoride on liquidus temperatures of the cryolite melts with a low cryolite ratio (CR) was studied. The systems KF-NaF-AlF3 and KF-LiF-AlF3 with CRs of 1.3, 1.5, and 1.7 have been investigated. The liquidus curves of systems containing CaF2 are different and depend on the K/(K + Na) and K/(K + Li) ratios. In potassium cryolite with CRs of 1.3 and 1.5, the calcium fluoride solubility is low and increases with NaF (LiF) concentration.

Apisarov, Alexei; Dedyukhin, Alexander; Nikolaeva, Elena; Tinghaev, Pavel; Tkacheva, Olga; Redkin, Alexander; Zaikov, Yurii

2011-02-01

309

Ultrahigh-Aspect-Ratio Contact Hole Etching  

NASA Astrophysics Data System (ADS)

An ultrasmall, 60nm-diameter, 2um-deep contact hole pattern of BPSG film was successfully fabricated using a poly-Si mask and a magnetically enhanced reactive-ion-etching system. Significantly weaker dependence of etch rate on aspect ratio(AR) was obtained up to AR=30, showing that the energetic ions (and/or neutralized molecules) with a sufficient flux for etching reaction are supplied onto the hole bottom even in such a extremely fine feature. On the other hand, neutral supply of polymer precursors onto the hole bottom (Si substrate) is not sufficient for polymerization in holes with aspect ratios greater than 10, where several energetic particles reach the hole bottoms and contribute to the etching reaction with Si substrates. For features with dimensions below 100nm, processing of vertical profiles is extremely difficult, and problems in the form of bowing at the sidewalls of the holes can occur. The shape of the etched feature and the occurrence of etch stops were shown to be in a trade-off relationship. However, vertical profiles were successfully obtained with diameters greater than 100nm without etch stops. It is possible that ion flux is significantly influenced (reduced) when ions pass through the poly-Si mask, rather than through the BPSG hole. The bowing is associated with bending of the incident ion trajectories, where the first stage of the trajectory change occurs at the mask, and subsequent multiple scattering of ions at the sidewall of the hole can occur. Other factors include sidewall protection by redeposited Si that was sputtered from the poly-Si mask and/or the deposited fluorocarbon polymers, and the effects of ion flux and energy bombarding these deposited materials. In the future, it will be necessary to clarify the details of the mechanisms of these phenomena and to establish technologies to control them. note number.

Ikegami, Naokatsu

1997-10-01

310

Poisson's Ratio in Composite Elastic Media with Rigid Rods  

NASA Astrophysics Data System (ADS)

We calculate both the micromechanical response and bulk elastic constants of composites of rods embedded in elastic media. We find two fixed points for Poisson’s ratio with respect to rod density: there is an unstable fixed point for Poisson’s ratio =1/2 (an incompressible system) and a stable fixed point for Poisson’s ratio =1/4 (a compressible system). We also derive approximate expressions for the elastic constants for arbitrary rod density, which agree with exact results for both low and high density. These results may help to explain recent experiments [Phys. Rev. Lett. 102, 188303 (2009)PRLTAO0031-900710.1103/PhysRevLett.102.188303] that reported compressibility for composites of microtubules in filamentous actin networks.

Das, Moumita; Mackintosh, F. C.

2010-09-01

311

Boron Isotope Ratios in Early B Stars from B III  

NASA Astrophysics Data System (ADS)

We propose to measure the ^11B/^10B ratio in the early Bstars HD 886 (Gamma Peg) and HD 35299, by obtaining very highsignal to noise ratio echelle-B spectra of the B IIIresonance line at 2066.8 Angstrom. Theoretical calculationspredict a 42 mA shift between the two isotopes, andboth synthetic spectra and high-dispersion IUE spectra showthat the line is present in both targets and is suitable formeasuring the isotope shift. The solar system ^11B/^10B ratioof 4:1 is considerably larger than the the canonicalpredictions of cosmic ray spallation theory (about 2.5:1).These observations will allow us to investigate whether or notthe solar system abundance ratio is universal among populationI stars, and will place new constraints on theories of ^11Bsynthesis.

Proffitt, Charles

1996-07-01

312

Eccentric crank variable compression ratio mechanism  

SciTech Connect

A variable compression ratio mechanism for an internal combustion engine that has an engine block and a crankshaft is disclosed. The variable compression ratio mechanism has a plurality of eccentric disks configured to support the crankshaft. Each of the plurality of eccentric disks has at least one cylindrical portion annularly surrounded by the engine block. The variable compression ratio mechanism also has at least one actuator configured to rotate the plurality of eccentric disks.

Lawrence, Keith Edward (Kobe, JP); Moser, William Elliott (Peoria, IL); Roozenboom, Stephan Donald (Washington, IL); Knox, Kevin Jay (Peoria, IL)

2008-05-13

313

Physics of Coanda jet detachment at high-pressure ratio  

NASA Astrophysics Data System (ADS)

Experimental measurements of surface pressure for an underexpanded two-dimensional supersonic Coanda flow with static conditions exterior to the jet flow was obtained for a fixed slot height to a radius ratio of 0.04. The data demonstrate that an oblique shock forms near the jet exit plane which vectors the jet flow from the curved surface at a pressure ratio of 7.6. The jet detachment occurs at a pressure ratio which is a function of the ratio of slot height to cylinder radius. An increase in the pressure ratio to 11.5 before jet detachment has been demonstrated by the translation of the upper wall providing for a converging-diverging geometry. The physics of the Coanda expansion and the jet detachment are qualitatively described using an optical schlieren system. A compressible inviscid model was derived analytically to demonstrate the variation in Mach number and surface pressure as a function of the geometric parameters with increasing pressure ratio.

Cornelius, Kenneth C.; Lucius, Gerald A.

1994-05-01

314

Einstein Hardness Ratios from a User-Developed IRAF Script  

NASA Astrophysics Data System (ADS)

Here we describe how IRAF/PROS was used to compute source hardness ratios for the recently published Einstein Catalog of IPC X-ray Sources. This catalog was prepared from the Imaging Proportional Counter (IPC) data of the Einstein X-ray Observatory, which operated in low-earth orbit from 1978 Nov until 1981 May. Before the catalog went to press, it was discovered that a bug in the production processing system had rendered the hardness ratios unreliable. For this reason, it was necessary to generate corrected hardness ratios for inclusion in the catalog. Our corrected hardness ratios were generated for ~4000 tabulated sources using the PI-corrected "qpoe" files from the IPC event list CDROMs. An IRAF script was written which, given a list of sources, performs spectral extraction and computes the source and background count values needed for the hardness ratio calculation. These values were used as input for a previously-developed maximum likelihood algorithm to compute hardness ratios and errors for the sources. Using existing IRAF commands and tasks, we were able to process a large amount of the data quickly and conveniently. For tasks such as detailed data formatting and file manipulation, however, it was convenient to invoke AWK and Unix scripts. This underscores the desirability of having heterogeneous analysis tools even more readily available to scientific users in a unified software environment.

Rhode, K. L.; Harnden, F. R., Jr.

315

Caste ratios affect the reproductive output of social trematode colonies.  

PubMed

Intraspecific phenotypic diversification in social organisms often leads to formation of physical castes which are morphologically specialized for particular tasks within the colony. The optimal caste allocation theory argues that specialized morphological castes are efficient at specific tasks, and hence different caste ratios should affect the ergonomic efficiency, hence reproductive output of the colony. However, the reproductive output of different caste ratios has been documented in few species of insects with equivocal support for the theory. This study investigated whether the ratios of nonreproductive and reproductive morphs affect the reproductive output of a recently discovered social trematode, Philophthalmus sp., in which the nonreproductive members are hypothesized to be defensive specialists. A census of natural infections and a manipulative in vitro experiment demonstrated a positive association between the reproductive output of trematode colonies and the ratio of nonreproductive to reproductive morphs in the presence of an intra-host trematode competitor, Maritrema novaezealandensis. On the contrary, without the competitor, reproductive output was negatively associated with the proportion of nonreproductive castes in colonies. Our findings demonstrate for the first time a clear fitness benefit associated with the nonreproductive castes in the presence of a competitor while illustrating the cost of maintaining such morphs in noncompetitive situations. Although the proximate mechanisms controlling caste ratio remain unclear in this trematode system, this study supports the prediction that the fitness of colonies is influenced by the composition of specialized functional morphs in social organisms, suggesting a potential for adaptive shifts of caste ratios over evolutionary time. PMID:23252707

Kamiya, T; Poulin, R

2012-12-17

316

Measurement of Poisson's ratio of dental composite restorative materials.  

PubMed

The aim of this study was to determine the Poisson ratio of resin-based dental composites using a static tensile test method. Materials used in this investigation were from the same manufacturer (3M ESPE) and included microfill (A110), minifill (Z100 and Filtek Z250), polyacid-modified (F2000), and flowable (Filtek Flowable [FF]) composites. The Poisson ratio of the materials were determined after 1 week conditioning in water at 37 degrees C. The tensile test was performed with using a uniaxial testing system at crosshead speed of 0.5 mm/min. Data was analysed using one-way ANOVA/post-hoc Scheffe's test and Pearson's correlation test at significance level of 0.05. Mean Poisson's ratio (n=8) ranged from 0.302 to 0.393. The Poisson ratio of FF was significantly higher than all other composites evaluated, and the Poisson ratio of A110 was higher than Z100, Z250 and F2000. The Poisson ratio is higher for materials with lower filler volume fraction. PMID:14751729

Chung, Sew Meng; Yap, Adrian U Jin; Koh, Wee Kiat; Tsai, Kuo Tsing; Lim, Chwee Teck

2004-06-01

317

Ecological genetics of sex ratios in plant populations.  

PubMed

In many angiosperm species, populations are reproductively subdivided into distinct sexual morphs including females, males and hermaphrodites. Sexual polymorphism is maintained by frequency-dependent selection, leading to predictable sex ratios at equilibrium. Charles Darwin devoted much of his book 'The Different Forms of Flowers on Plants of the Same Species' (1877) to investigating plant sexual polymorphisms and laid the foundation for many problems addressed today by integrating theory with empirical studies of the demography and genetics of populations. Here, we summarize our recent work on the ecological and genetic mechanisms influencing variation in sex ratios and their implications for evolutionary transitions among sexual systems. We present the results of a survey of sex ratios from 126 species from 47 angiosperm families and then address two general problems using examples from diverse angiosperm taxa: (i) the mechanisms governing biased sex ratios in dioecious species; (ii) the origins and maintenance of populations composed of females, males and hermaphrodites. Several themes are emphasized, including the importance of non-equilibrium conditions, the role of life history and demography in affecting sex ratios, the value of theory for modelling the dynamics of sex ratio variation, and the utility of genetic markers for investigating evolutionary processes in sexually polymorphic plant populations. PMID:20643745

Barrett, Spencer C H; Yakimowski, Sarah B; Field, David L; Pickup, Melinda

2010-08-27

318

Dependence of the Oxygen Enhancement Ratio on Neutron Energy  

Microsoft Academic Search

THE data reported by Barendsen and Broerse1 for the oxygen enhancement ratios in human cell cultures subjected to neutron radiation have prompted us to report the values which we have obtained for a completely different biological system-that of induction of somatic mutation in the staminal hair cells of a diploid clone (02) derived from a variety of Tradescantia occidentalis. Briefly,

J. A. Dennis; S. J. Boot

1967-01-01

319

A measurement of the inclusive b? s? branching ratio  

Microsoft Academic Search

The flavour changing neutral current decay b?s? has been detected in hadronic Z decays collected by ALEPH at LEP. The signal is isolated in lifetime-tagged bb? events by the presence of a hard photon associated with a system of high momentum and high rapidity hadrons. The background processes are normalised from the data themselves. The inclusive branching ratio is measured

R. Barate; D. Buskulic; D. Decamp; P. Ghez; C. Goy; J.-P. Lees; A. Lucotte; E. Merle; M.-N. Minard; J.-Y. Nief; B. Pietrzyk; R. Alemany; G. Boix; M. P. Casado; M. Chmeissani; J. M. Crespo; M. Delfino; E. Fernandez; M. Fernandez-Bosman; Ll. Garrido; E. Graugès; A. Juste; M. Martinez; G. Merino; R. Miquel; Ll. M. Mir; I. C. Park; A. Pascual; J. A. Perlas; I. Riu; F. Sanchez; A. Colaleo; D. Creanza; M. de Palma; G. Gelao; G. Iaselli; G. Maggi; M. Maggi; S. Nuzzo; A. Ranieri; G. Raso; F. Ruggieri; G. Selvaggi; L. Silvestris; P. Tempesta; A. Tricomi; G. Zito; X. Huang; J. Lin; Q. Ouyang; T. Wang; Y. Xie; R. Xu; S. Xue; J. Zhang; L. Zhang; W. Zhao; D. Abbaneo; U. Becker; P. Bright-Thomas; D. Casper; M. Cattaneo; V. Ciulli; G. Dissertori; H. Drevermann; R. W. Forty; M. Frank; R. Hagelberg; J. B. Hansen; J. Harvey; P. Janot; B. Jost; I. Lehraus; P. Mato; A. Minten; L. Moneta; A. Pacheco; J.-F. Pusztaszeri; F. Ranjard; L. Rolandi; D. Rousseau; D. Schlatter; M. Schmitt; O. Schneider; W. Tejessy; F. Teubert; I. R. Tomalin; H. Wachsmuth; Z. Ajaltouni; F. Badaud; G. Chazelle; O. Deschamps; A. Falvard; C. Ferdi; P. Gay; C. Guicheney; P. Henrard; J. Jousset; B. Michel; S. Monteil; J. C. Montret; D. Pallin; P. Perret; F. Podlyski; J. Proriol; P. Rosnet; J. D. Hansen; P. H. Hansen; B. S. Nilsson; B. Rensch; A. Wäänänen; G. Daskalakis; A. Kyriakis; C. Markou; E. Simopoulou; I. Siotis; A. Vayaki; A. Blondel; G. Bonneaud; J.-C. Brient; P. Bourdon; A. Rougé; M. Rumpf; A. Valassi; M. Verderi; H. Videau; E. Focardi; G. Parrini; K. Zachariadou; M. Corden; C. Georgiopoulos; D. E. Jaffe; A. Antonelli; G. Bencivenni; F. Bossi; P. Campana; G. Capon; F. Cerutti; V. Chiarella; G. Felici; P. Laurelli; G. Mannocchi; F. Murtas; G. P. Murtas; L. Passalacqua; M. Pepe-Altarelli; L. Curtis; A. W. Halley; J. G. Lynch; P. Negus; V. O'Shea; C. Raine; J. M. Scarr; K. Smith; P. Teixeira-Dias; A. S. Thompson; E. Thomson; O. Buchmüller; S. Dhamotharan; C. Geweniger; G. Graefe; P. Hanke; G. Hansper; V. Hepp; E. E. Kluge; A. Putzer; J. Sommer; K. Tittel; S. Werner; M. Wunsch; R. Beuselinck; D. M. Binnie; W. Cameron; P. J. Dornan; M. Girone; S. Goodsir; E. B. Martin; N. Marinelli; A. Moutoussi; J. Nash; J. K. Sedgbeer; P. Spagnolo; M. D. Williams; V. M. Ghete; P. Girtler; E. Kneringer; D. Kuhn; G. Rudolph; A. P. Betteridge; C. K. Bowdery; P. G. Buck; P. Colrain; G. Crawford; A. J. Finch; F. Foster; G. Hughes; R. W. L. Jones; N. A. Robertson; T. Sloan; M. I. Williams; I. Giehl; A. M. Greene; C. Hoffmann; K. Jakobs; K. Kleinknecht; G. Quast; B. Renk; E. Rohne; H.-G. Sander; P. van Gemmeren; C. Zeitnitz; J. J. Aubert; C. Benchouk; A. Bonissent; G. Bujosa; J. Carr; P. Coyle; F. Etienne; O. Leroy; F. Motsch; P. Payre; M. Talby; A. Sadouki; M. Thulasidas; K. Trabelsi; M. Aleppo; M. Antonelli; F. Ragusa; R. Berlich; W. Blum; V. Büscher; H. Dietl; G. Ganis; H. Kroha; G. Lütjens; C. Mannert; W. Männer; H.-G. Moser; S. Schael; R. Settles; H. Seywerd; H. Seywerd; W. Wiedenmann; G. Wolf; J. Boucrot; O. Callot; S. Chen; A. Cordier; M. Davier; L. Duflot; J.-F. Grivaz; Ph. Heusse; A. Höcker; A. Jacholkowska; D. W. Kim; F. Le Diberder; J. Lefrançois; A.-M. Lutz; M.-H. Schune; E. Tournefier; J.-J. Veillet; I. Videau; D. Zerwas; P. Azzurri; G. Bagliesi; G. Batignani; S. Bettarini; T. Boccali; C. Bozzi; G. Calderini; M. Carpinelli; M. Carpinelli; R. Dell'Orso; R. Fantechi; I. Ferrante; L. Foà; F. Forti; A. Giassi; M. A. Giorgi; M. A. Giorgi; F. Ligabue; A. Lusiani; P. S. Marrocchesi; A. Messineo; F. Palla; G. Rizzo; G. Sanguinetti; A. Sciabà; G. Sguazzoni; R. Tenchini; G. Tonelli; C. Vannini; A. Venturi; P. G. Verdini; G. A. Blair; L. M. Bryant; J. T. Chambers; M. G. Green; T. Medcalf; P. Perrodo; J. A. Strong; J. H. von Wimmersperg-Toeller; D. R. Botterill; R. W. Clifft; T. R. Edgecock; S. Haywood; P. R. Norton; J. C. Thompson; A. E. Wright; B. Bloch-Devaux; P. Colas; S. Emery; W. Kozanecki; E. Lançon; M.-C. Lemaire; E. Locci; P. Perez; J. Rander; J.-F. Renardy; A. Roussarie; J.-P. Schuller; J. Schwindling; A. Trabelsi; B. Vallage; S. N. Black; J. H. Dann; R. P. Johnson; H. Y. Kim; N. Konstantinidis; A. M. Litke; M. A. McNeil; G. Taylor; C. N. Booth; C. A. J. Brew; S. Cartwright; F. Combley; M. S. Kelly; M. Lehto; J. Reeve; L. F. Thompson; K. Affholderbach; A. Böhrer; S. Brandt; G. Cowan; C. Grupen; P. Saraiva; L. Smolik; F. Stephan; G. Giannini; B. Gobbo; G. Musolino; J. Rothberg; S. Wasserbaech; S. R. Armstrong; E. Charles; P. Elmer; D. P. S. Ferguson; Y. Gao; S. González; T. C. Greening; O. J. Hayes; H. Hu; S. Jin; P. A. McNamara III; J. M. Nachtman; J. Nielsen; W. Orejudos; Y. B. Pan; Y. Saadi; I. J. Scott; J. Walsh; Sau Lan Wu; X. Wu; G. Zobernig

1998-01-01

320

A Study of Viterbi's Ratio-Threshold AJ Technique  

Microsoft Academic Search

In this paper we study the performance of several AJ systems based on Viterbi's ratio-threshold technique for FH\\/SS communications. Innovative features of our work include the use of channel capacity as the figure of merit, and the use of randomly varying thresholds.

Li-Fung ChangandRobert; Robert J. McEliece

1984-01-01

321

A mixing ratios-based formulation for multicomponent reactive transport  

Microsoft Academic Search

Chemical reactions are driven by disequilibrium, which is often caused by mixing. Therefore quantification of the mixing rate is essential for evaluating the fate of solutes in natural systems, such as rivers, lakes, and aquifers. We propose a novel mixing ratios-based formulation to evaluate solute concentrations and reaction rates when equilibrium aqueous reactions and precipitation\\/dissolution of minerals are driven by

M. De Simoni; X. Sanchez-Vila; J. Carrera; M. W. Saaltink

2007-01-01

322

Analysis of Ratios in Multivariate Morphometry  

PubMed Central

The analysis of ratios of body measurements is deeply ingrained in the taxonomic literature. Whether for plants or animals, certain ratios are commonly indicated in identification keys, diagnoses, and descriptions. They often provide the only means for separation of cryptic species that mostly lack distinguishing qualitative characters. Additionally, they provide an obvious way to study differences in body proportions, as ratios reflect geometric shape differences. However, when it comes to multivariate analysis of body measurements, for instance, with linear discriminant analysis (LDA) or principal component analysis (PCA), interpretation using body ratios is difficult. Both techniques are commonly applied for separating similar taxa or for exploring the structure of variation, respectively, and require standardized raw or log-transformed variables as input. Here, we develop statistical procedures for the analysis of body ratios in a consistent multivariate statistical framework. In particular, we present algorithms adapted to LDA and PCA that allow the interpretation of numerical results in terms of body proportions. We first introduce a method called the “LDA ratio extractor,” which reveals the best ratios for separation of two or more groups with the help of discriminant analysis. We also provide measures for deciding how much of the total differences between individuals or groups of individuals is due to size and how much is due to shape. The second method, a graphical tool called the “PCA ratio spectrum,” aims at the interpretation of principal components in terms of body ratios. Based on a similar idea, the “allometry ratio spectrum” is developed which can be used for studying the allometric behavior of ratios. Because size can be defined in different ways, we discuss several concepts of size. Central to this discussion is Jolicoeur's multivariate generalization of the allometry equation, a concept that was derived only with a heuristic argument. Here we present a statistical derivation of the allometric size vector using the method of least squares. The application of the above methods is extensively demonstrated using published data sets from parasitic wasps and rock crabs.

Baur, Hannes; Leuenberger, Christoph

2011-01-01

323

Atmospheric helium isotope ratio: Possible temporal and spatial variations  

NASA Astrophysics Data System (ADS)

The atmospheric 3He/ 4He ratio has been considered to be constant on a global scale, because the residence time of helium is significantly longer than the mixing time in the atmosphere. However, this ratio may be decreasing with time owing to the anthropogenic release of crustal helium from oil and natural gas wells, although this observation has been disputed. Here, we present the 3He/ 4He ratios of old air trapped in historical slags in Japan and of modern surface air samples collected at various sites around the world, measured with a newly developed analytical system. In air helium extracted from metallurgical slag found at refineries in operation between AD 1603 and 1907 in Japan, we determined a mean 3He/ 4He ratio of (5106 ± 108) × 10 -5 R HESJ (where R HESJ is the 3He/ 4He ratio of the Helium Standard of Japan), which is consistent with the previously reported value of (5077 ± 59) × 10 -5 R HESJ for historical slags in France and United Arab Emirates and about 4% higher than that of average modern air, (4901 ± 4) × 10 -5 R HESJ. This result implies that the air 3He/ 4He ratio has decreased with time as expected by anthropogenic causes. Our modern surface air samples revealed that the 3He/ 4He ratio increases from north to south at a rate of (0.16 ± 0.08) × 10 -5 R HESJ/degree of latitude, suggesting that the low 3He/ 4He ratio originates in high-latitude regions of the northern hemisphere, which is consistent with the fact that most fossil fuel is extracted and consumed in the northern hemisphere.

Sano, Yuji; Furukawa, Yukiko; Takahata, Naoto

2010-09-01

324

Population Dynamics under Parasitic Sex Ratio Distortion  

Microsoft Academic Search

We analyse the population dynamic effects of sex ratio distortion by vertically transmitted, feminizing parasites. We show that, for diploid hosts, sex ratio distortion may lead to extinction as males become too rare to maintain the host population through reproduction. Feminizers can magnify Allee effects, broadening the range of conditions leading to extinction of small populations. Depending on male mating

Melanie J. Hatcher; Dale E. Taneyhill; Alison M. Dunn; Chris Tofts

1999-01-01

325

GOLDEN RATIO-HAAR WAVELET BASED STEGANOGRAPHY  

Microsoft Academic Search

In this paper, we have presented the golden ratio-Haar wavelet based multimedia steganography. The key features of the proposed method are: 1. New Haar wavelet structure based on the Fibonacci se- quence, and Golden Ratio. 2. Parametric transform dependency, as decryption key, on the security of the sensitive data. One of the important differences between the existing trans- form based

Sos S. Agaian; Okan Caglayan; Juan Pablo Perez; Hakob Sarukhanyan; Jaakko Astola

326

Graphs (networks) with golden spectral ratio  

Microsoft Academic Search

We propose two new spectral measures for graphs and networks which characterize the ratios between the width of the “bulk” part of the spectrum and the spectral gap, as well as the ratio between spectral spread and the width of the “bulk” part of the spectrum. Using these definitions we introduce the concept of golden spectral graphs (GSG), which are

Ernesto Estrada; Edificio CACTUS

2007-01-01

327

The Divine Ratio and Golden Rectangles.  

ERIC Educational Resources Information Center

|The material examines aspects of Fibonacci and Lucas sequences, the generation of the Divine Ratio, and the nature of this ratio in golden rectangles, triangles, and figures made up of golden triangles. It is noted Lucas sequence is formed like Fibonacci but has one and three as the first elements. (Author/MP)|

Cooper, Martin

1982-01-01

328

Financial Ratio Analysis Comes to Nonprofits.  

ERIC Educational Resources Information Center

|To evaluate their financial health, a growing number of colleges, universities, and other nonprofit organizations are using financial ratio analysis, a technique used in business. The strengths and weaknesses of ratio analysis are assessed and suggestions are made on how nonprofits can use it most effectively. (Author/MLW)|

Chabotar, Kent John

1989-01-01

329

Sports classiflcation using cross-ratio histograms  

Microsoft Academic Search

The paper proposes a novel approach for classiflcation of sports images based on the geometric information encoded in the image of a sport's fleld. The proposed approach uses invariant nature of a cross- ratio under projective transformation to develop a robust classifler. For a given image, cross-ratios are computed for the points obtained from the intersection of lines detected using

Balamanohar Paluri; Nalin Pradeep S; Hitesh Shah; Prakash C

330

Sulfate washout ratios in winter storms  

Microsoft Academic Search

Washout ratios for sulfate were computed from simultaneous measurements of sulfate in precipitation and in the air below cloud base. Stratification of the data according to predominant mode of precipitation growth (growth primarily by accretion of liquid cloud droplets versus growth primarily by vapor deposition onto ice particles) illustrated that for cases of accretional growth, the washout ratio was 10--50

B. C. Scott

1981-01-01

331

Economy Track: Employment to Population Ratio  

NSDL National Science Digital Library

Time plot compares the employment-population ratio - the broadest measure of people who are working in America. Allows to compare between recessions, also allows to compare between demographic groups -- by sex, race/ethnicity and educational attainment. Also shows the secular trend for employment-population ratio since 1973.

Institute, Economic P.

332

Likelihood Ratio Tests for Special Rasch Models  

ERIC Educational Resources Information Center

In this article, a general class of special Rasch models for dichotomous item scores is considered. Although Andersen's likelihood ratio test can be used to test whether a Rasch model fits to the data, the test does not differentiate between special Rasch models. Therefore, in this article, new likelihood ratio tests are proposed for testing…

Hessen, David J.

2010-01-01

333

Osmosis and Surface Area to Volume Ratio.  

ERIC Educational Resources Information Center

|Describes an experiment designed to help students understand the concepts of osmosis and surface area to volume ratio (SA:VOL). The task for students is to compare water uptake in different sizes of potato cubes and relate differences to their SA:VOL ratios. (JN)|

Barrett, D. R. B.

1984-01-01

334

Aging and Weight-Ratio Perception  

PubMed Central

Past research has provided evidence that older adults have more difficulty than younger adults in discriminating small differences in lifted weight (i.e., the difference threshold for older adults is higher than that of younger adults). Given this result, one might expect that older adults would demonstrate similar impairments in weight ratio perception (a suprathreshold judgment) compared to younger adults. The current experiment compared the abilities of younger and older adults to perceive weight ratios. On any given trial, participants lifted two objects in succession and were asked to provide an estimate of the objects’ weight ratio (the weight of the heavier object relative to the lighter). The results showed that while the older participants’ weight ratio estimates were as reliable as those of the younger participants, they were significantly less accurate: the older participants frequently perceived the weight ratios to be much higher than they actually were.

Holmin, Jessica S.; Norman, J. Farley

2012-01-01

335

Ratio responding as a function of concurrent avoidance schedules, yoked shocks, and ratio value  

PubMed Central

Fixed-ratio food-reinforced responding in rats was studied alone and with concurrent shock avoidance or with concurrent response-independent shocks matched to those that occurred in the avoidance condition. Under each condition, fixed-ratio size was increased over successive daily sessions. Fixed-ratio response rate generally passed through a maximum as a function of fixed-ratio size. Decreased fixed-ratio responding at values beyond the maximum occurred when (1) the time to complete a fixed ratio approximated the response-shock interval of the avoidance schedule, (2) the shock rate increased, and/or (3) the ratio requirements were so high that ratio strain occurred. Avoidance rates decreased slightly as fixed-ratio size increased.

Wood, Keith A.; Happ, Alan J.; Adams, Calvin K.

1983-01-01

336

Sensitivity of stoichiometric ratios to temporal variability in streamflow  

NASA Astrophysics Data System (ADS)

Increasing nutrient fluxes through river systems can contribute to the eutrophication and degradation of downstream aquatic ecosystems. The severity of these environmental impacts partially depends on the relative abundance of nutrients, which limit primary productivity and species composition. Stoichiometric ratios of nitrogen (N), phosphorus (P) and silicon (Si) in river systems are regulated by river discharge both directly, through the movement of dissolved constituents, and indirectly, through the transport of particulate nutrients adsorbed to sediment. As a result, hydrologic flow patterns can potentially inform predictions on the biogeochemical state of river systems. This study examines 18 independent sub-basins in the Mississippi River Basin to assess the relationship between nutrient ratios and temporal variability in river discharge. Monthly-averaged data show that, in general, N:P ratios increase with increasing river discharge for agriculturally dominated basins, and decrease with increasing discharge for basins with low agricultural activity. This suggests that nitrogen supply is virtually unlimited in rivers that drain agricultural basins and that nitrogen losses may accelerate more rapidly in these watersheds. Seasonal patterns reveal a complex relationship between stoichiometric ratios and streamflow that depends on the relative timing of peak flow with agricultural activity and fertilizer/manure inputs, as well as the dynamics of in-stream nutrient removal and sediment transport.

Donner, S. D.; Leong, D. N.; Covino, T. P.; Gabor, R. S.; Drummond, J. D.; Xu, X.

2010-12-01

337

Sex ratio in relation to fathers' occupations.  

PubMed Central

OBJECTIVE: To investigate whether the sex ratio of children varies between fathers of different occupations. METHODS: The sex ratio (the ratio of the number of boys to the number of girls at birth) was calculated in relation to paternal occupation in the cohort of all 253,433 live births in Cumbria, north west England, from 1950-89. Exact binomial confidence intervals were used to estimate whether the sex ratio in each occupational category was significantly different from that for the rest of the cohort. RESULTS: There were fewer occupational categories with significantly different sex ratios at the 5% level than expected by chance alone, assuming the same binomial distribution of sexes at birth within each paternal occupation. CONCLUSIONS: Significant variation of the sex ratio with fathers' occupations was not found. There is some evidence that the sex ratio shows less variance than expected under a binomial model which assumes independence of the sex of each child; a possible explanation of this may be parental preference for limiting family size after children of both sexes have been born or some other factor which results in children within a family being more likely to be of both sexes rather than the same sex.

Dickinson, H O; Parker, L

1997-01-01

338

C/O Ratios in Exoplanetary Atmospheres  

NASA Astrophysics Data System (ADS)

Recent observations are allowing unprecedented constraints on the carbon-to-oxygen (C/O) ratios of giant exoplanetary atmospheres. Elemental abundance ratios, such as the C/O ratio, of planetary atmospheres provide important constraints on planetary interior compositions and formation conditions, and on the chemical and dynamical processes in the atmospheres. In addition, for super-Earths, the potential availability of water and oxygen, and hence the notion of `habitability', is contingent on the C/O ratio. Typically, an oxygen-rich composition, motivated by the solar nebula C/O of 0.5, is assumed in models of exoplanetary formation, interiors, and atmospheres. However, recent observations of exoplanetary atmospheres are suggesting the possibility of C/O ratios of 1.0 or higher, motivating the new class of Carbon-rich Planets (CRPs). In this talk, we will present observational constraints on atmospheric C/O ratios for an ensemble of transiting exoplanets and discuss their implications on the various aspects of exoplanetary characterization described above. Motivated by these results, we propose a two-dimensional classification scheme for irradiated giant exoplanets in which the incident irradiation and the atmospheric C/O ratio are the two dimensions. We demonstrate that some of the extreme anomalies reported in the literature for hot Jupiter atmospheres can be explained based on this 2-D scheme. An overview of new theoretical avenues and observational efforts underway for chemical characterization of extrasolar planets, from hot Jupiters to super-Earths, will be presented.

Madhusudhan, N.

2012-04-01

339

On the minimum mass ratio of W UMa binaries  

NASA Astrophysics Data System (ADS)

Using Eggleton's stellar evolution code, we study the minimum mass ratio (qmin) of W Ursae Majoris (W UMa) binaries that have different primary masses. It is found that the minimum mass ratio of W UMa binaries decreases with increasing mass of the primary if the primary's mass is less than about 1.3Msolar, while above this mass the ratio is roughly constant. By comparing the theoretical minimum mass ratio with observational data, it is found that the existence of low-q systems can be explained by the different structure of primaries with different masses. This suggests that the dimensionless gyration radius (k21) and thus the structure of the primary is very important in determining the minimum mass ratio. In addition, we investigate the mass loss during the merging process of W UMa systems and calculate the rotation velocities of the single stars formed by mergers of W UMa binaries due to tidal instability. It is found that in the case of conservation of mass and angular momentum, the merged single stars rotate with an equatorial velocity of about ~588-819kms-1, which is much larger than their break-up velocities (vb). This suggests that the merged stars should extend to a very large radius (~3.7-5.3 times the radii of the primaries) or else W UMa systems should lose a large amount of mass (~21-33 per cent of the total mass) during the merging process. If the effect of magnetic braking is considered, the mass loss decreases to ~12-18 per cent of the total mass. This implies that significant angular momentum and mass might be lost from W UMa systems in the course of the merging process, and this kind of mass and angular momentum loss might be driven by the release of orbital energy of the secondaries, similarly to common-envelope evolution.

Jiang, Dengkai; Han, Zhanwen; Wang, Jiancheng; Jiang, Tianyu; Li, Lifang

2010-07-01

340

The golden ratio in facial symmetry.  

PubMed

Symmetry is believed to be a hallmark of appealing faces. However, this does not imply that the most aesthetically pleasing proportions are necessary those that arise from the simple division of the face into thirds or fifths. Based on the etymology of the word symmetry, as well as on specific examples and theories of beauty, we conclude that ?-value, a ratio also known as the golden ratio or the divine proportion, can also characterize symmetrical forms. Therefore, we propose the utilization of this ratio in facial aesthetics. PMID:23441307

Prokopakis, E P; Vlastos, I M; Picavet, V A; Nolst Trenite, G; Thomas, R; Cingi, C; Hellings, P W

2013-03-01

341

Branching Ratios for K+-->3? Decays  

NASA Astrophysics Data System (ADS)

The branching ratios ?'+(K+-->all) and ?'+?+ were obtained from a sample of 12 976K+ decays including 198 ?'+ and 693?+ decays. It was found that ?'+(K+-->all)=0.0153+/-0.0011, and that ?'+?+=0.286+/-0.023. The ?+(K+-->all) branching ratio and the ?+ energy spectrum in ?'+ decay were also obtained, and were found to be in good agreement with the more precise determinations of the other experiments. The branching-ratio data suggest a small ?I=32 admixture in the K-->3? decay amplitudes. Comparison with various theoretical models shows fair to good agremeent between experiment and theory.

Pandoulas, D.; Taylor, S.; Koller, E. L.; Grauman, J.; Hoffmaster, S.; Raths, O.; Romano, L.; Stamer, P.

1970-10-01

342

Product Branching Ratios in Dissociative Recombination of HeH^+  

NASA Astrophysics Data System (ADS)

The cross section and branching ratios into final states for dissociative recombination of low-energy (<= 10 eV) electrons with HeH^+ are calculated using a time-dependent wave-packet method. The process in this energy regime proceeds by non-adiabatic coupling from the electron-ion system and the Rydberg states. In agreement with the experimental results, as each new final channel opens, it dominates the branching ratio. The effects on the cross section and branching ratios of high-lying closed Rydberg states, coupling between the Rydberg states, and autoionization via non-adiabatic coupling are studied. This work was supported by the National Science Foundation, Grant No.PHY-99-87877.

Orel, A. E.; Larson, A.

2002-05-01

343

Can We Detect Intermediate-mass-ratio Inspirals with LISA?  

NASA Astrophysics Data System (ADS)

Gravitational waves emitted during intermediate-mass-ratio inspirals (IMRIs) of intermediate-mass black holes (IMBHs) into supermassive black holes could represent a very interesting source for LISA. Similarly, IMRIs of stellar-mass compact objects into IMBHs could be detectable by Advanced LIGO. At present, however, it is not clear what waveforms could be used for IMRI detection, since the post-Newtonian approximation breaks down as an IMRI approaches the innermost stable circular orbit, and the perturbative solution is only known to the lowest order in the mass ratio. We discuss the expected mismatches between approximate and true waveforms, and the choice of the best available waveform as a function of the mass ratio and the total mass of the system. We also comment on the significance of the spin of the smaller body and the need for its inclusion in the waveforms. This research is partially supported by NASA ATP Grant NNX07AH22G to Northwestern University.

Mandel, Ilya; Gair, J. R.

2009-01-01

344

Perceived image quality of 16:9 and 4:3 aspect ratio video displays  

Microsoft Academic Search

With the development of high-definition television (HDTV) systems came the 16:9 (width to height) viewing image aspect ratio. This is compared to the National Television System Committee (NTSC) standard ration of 4:3 (width to height). This variation in width-to-height aspect ratio has led to the question of which ratio is preferred by the viewing public. The use of a paired-comparison

Brant D. Nystrom; Mark D. Fairchild

1992-01-01

345

Oxidative ratio (OR) of UK peats  

NASA Astrophysics Data System (ADS)

The oxidative ratio (OR) is the amount of CO2 sequestered in the terrestrial biosphere for each mol of O2 produced. The OR governs the effectiveness of a terrestrial biome to mitigate the impact of anthropogenic CO2 emissions and it has been used to calculate the balance of terrestrial and oceanic carbon sinks across the globe. However, few studies have investigated the controls of the variability in OR. What factors affect OR - climate? Soil type? Vegetation type? N deposition? Land use? Land use change? Small shifts in OR could have important implications in the global partitioning of CO2 between the atmosphere, biosphere, and oceans. This study looks at peat soils (Histosols) from a series of sites representing a climatic transect across the UK. Duplicate peat cores were taken, along with samples of above-ground vegetation and litter, from sites in northern Scotland (Forsinard), southern Scotland (Auchencorth), northern England (Moor House; Thorne Moor) through the Welsh borders (Whixhall Moss) and Somerset levels (Westhay Moor) to Dartmoor and Bodmin Moor in the south west of England. Sub-samples of the cores were analysed for their CHNO concentrations using a Costech ECS 4010 Elemental combustion system. Using the method of Masiello et al. (2008), OR values could be calculated from these elemental concentrations. Initial results show that OR values of UK peats varied between 0.94 and 1.1 with a median value of 1.05 which similar to the median value of World soils but the range is at the more reduced end. There was significant variation between peat cores, even between peat cores on the same site and the peat showed significant reduction in OR with depth in the core.

Clay, G. D.; Worrall, F.; Masiello, C. A.

2012-04-01

346

34 CFR 668.172 - Financial ratios.  

Code of Federal Regulations, 2013 CFR

...Excludes all unsecured or uncollateralized related-party receivables; (4) Excludes all intangible assets defined as intangible...from the ratio calculations. (Approved by the Office of Management and Budget under control number 1840-0537)...

2013-07-01

347

Anomalous Enantiomer Ratios in Meteoritic Sugar Derivatives  

NASA Astrophysics Data System (ADS)

The enantiomer (mirror-image) ratios of sugar acids in carbonaceous meteorites have been measured. D-enantiomer excesses are found in all acids measured thus far. This includes rare as well as common compounds.

Cooper, G.; Sant, M.; Asiyo, C.

2009-03-01

348

Quantifying absolute carbon isotope ratios by AMS  

NASA Astrophysics Data System (ADS)

Our AMS produced a ratio of instrument transmissions for 14C and 13C equal to 13/14 to 0.22 ± 0.06% accuracy at a specific charge-changing energy of 235 keV and giving absolute isotope ratios with that mass correction. The ratio for 13C and 12C transmissions was 12/13 at 215 keV. A differential equation model of energetic ion and atom transport through the gas collision cell was constructed with functions representing experimental cross-sections for all collision effects. This model showed cation yield dependencies that were linear with energy for the monoenergetic isotopic ions at the energies that we measured, explaining the inverse mass dependence. The model predicted multiple lower energies that have this dependence and, more importantly, two low energies at which cation yields were equal for pairs of isotopes, presaging potential absolute isotope ratio measurements at low MS energies.

Vogel, John S.; Giacomo, Jason A.; Dueker, Stephen R.

2013-01-01

349

Science Application of Area and Ratio Concepts  

ERIC Educational Resources Information Center

This article describes using area and ratio concepts to examine why some animals, or people wearing different types of shoes, sink into the surface on which they are standing. Students compute "sinking values" to explain these differences. (Contains 2 figures.)

Horak, Virginia M.

2006-01-01

350

40 CFR - to-Fuel Ratio Measurements  

Code of Federal Regulations, 2010 CFR

...false to-Fuel Ratio Measurements Air Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES...use O2 measurements with intake air or fuel flow measurements to...

2009-07-01

351

40 CFR - to-Fuel Ratio Measurements  

Code of Federal Regulations, 2010 CFR

...false to-Fuel Ratio Measurements Air Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES...use O2 measurements with intake air or fuel flow measurements to...

2010-07-01

352

Ratio Analysis: Where Investments Meet Mathematics.  

ERIC Educational Resources Information Center

|Discusses ratio analysis by which investments may be evaluated. Requires the use of fundamental mathematics, problem solving, and a comparison of the mathematical results within the framework of industry. (Author/NB)|

Barton, Susan D.; Woodbury, Denise

2002-01-01

353

Male pygmy hippopotamus influence offspring sex ratio  

PubMed Central

Pre-determining fetal sex is against the random and equal opportunity that both conceptus sexes have by nature. Yet, under a wide variety of circumstances, populations shift their birth sex ratio from the expected unity. Here we show, using fluorescence in situ hybridization, that in a population of pygmy hippopotamus (Choeropsis liberiensis) with 42.5% male offspring, males bias the ratio of X- and Y-chromosome-bearing spermatozoa in their ejaculates, resulting in a 0.4337±0.0094 (mean±s.d.) proportion of Y-chromosome-bearing spermatozoa. Three alternative hypotheses for the shifted population sex ratio were compared: female counteract male, female indifferent, or male and female in agreement. We conclude that there appears little or no antagonistic sexual conflict, unexpected by prevailing theories. Our results indicate that males possess a mechanism to adjust the ratio of X- and Y-chromosome-bearing spermatozoa in the ejaculate, thereby substantially expanding currently known male options in sexual conflict.

Saragusty, Joseph; Hermes, Robert; Hofer, Heribert; Bouts, Tim; Goritz, Frank; Hildebrandt, Thomas B.

2012-01-01

354

Doing Mathematics with Bicycle Gear Ratios.  

ERIC Educational Resources Information Center

|Describes an activity in which students examine bicycle chain-rings, cogs, and gear ratios as a means of exploring algebraic relationships, data collection, scatter plots, and lines of best fit. (KHR)|

Stump, Sheryl L.

2000-01-01

355

Difference and Ratio Inequalities in Hilbert Space.  

National Technical Information Service (NTIS)

Some inequalities involving differences and ratios of means give rise, using the spectral theorem for bounded, symmetric operators in Hilbert space, to inequalities involving such operators. Further operator inequalities are derived, some of which are ana...

B. Mond O. Shisha

1970-01-01

356

Necessary Intransitive Likelihood-Ratio Classifiers  

Microsoft Academic Search

In pattern classification tasks, errors are introduced because of differ- ences between the true generative model and the one obtained via model estimation. Using likelihood-ratio based classification, it is possible to correct for this discrepancy by finding class-pair specific terms to adjust the likelihood ratio directly, and that can make class-pair preference rela- tionships intransitive. In this work, we introduce

Gang Ji; Jeff A. Bilmes

2003-01-01

357

Bayesian analysis for monotone hazard ratio  

Microsoft Academic Search

We propose a Bayesian approach for estimating the hazard functions under the constraint of a monotone hazard ratio. We construct\\u000a a model for the monotone hazard ratio utilizing the Cox’s proportional hazards model with a monotone time-dependent coefficient.\\u000a To reduce computational complexity, we use a signed gamma process prior for the time-dependent coefficient and the Bayesian\\u000a bootstrap prior for the

Yongdai Kim; Jin Kyung Park; Gwangsu Kim

2011-01-01

358

A Power Divider with Adjustable Dividing Ratio  

NASA Astrophysics Data System (ADS)

An unequal Wilkinson power divider with adjustable power dividing ratio is proposed. The proposed power divider consists of rectangular defected ground structure (DGS), isolated island in DGS, and varactor diodes. The impedance of the microstrip line greatly increases due to the DGS, and varies because of the varying capacitance of diodes. The measured unequal dividing ratios vary from 1.97-13.4 and 2.25-10.6 when 2- and 4-diodes are adopted.

Lim, Jongsik; Oh, Seongmin; Koo, Jae-Jin; Jeong, Yongchae; Ahn, Dal

359

Three-dimensional stereo by photometric ratios  

SciTech Connect

We present a methodology for corresponding a dense set of points on an object surface from photometric values for three-dimensional stereo computation of depth. The methodology utilizes multiple stereo pairs of images, with each stereo pair being taken of the identical scene but under different illumination. With just two stereo pairs of images taken under two different illumination conditions, a stereo pair of ratio images can be produced, one for the ratio of left-hand images and one for the ratio of right-hand images. We demonstrate how the photometric ratios composing these images can be used for accurate correspondence of object points. Object points having the same photometric ratio with respect to two different illumination conditions constitute a well-defined equivalence class of physical constraints defined by local surface orientation relative to illumination conditions. We formally show that for diffuse reflection the photometric ratio is invariant to varying camera characteristics, surface albedo, and viewpoint and that therefore the same photometric ratio in both images of a stereo pair implies the same equivalence class of physical constraints. The correspondence of photometric ratios along epipolar lines in a stereo pair of images under different illumination conditions is a correspondence of equivalent physical constraints, and the determination of depth from stereo can be performed. Whereas illumination planning is required, our photometric-based stereo methodology does not require knowledge of illumination conditions in the actual computation of three-dimensional depth and is applicable to perspective views. This technique extends the stereo determination of three-dimensional depth to smooth featureless surfaces without the use of precisely calibrated lighting. We demonstrate experimental depth maps from a dense set of points on smooth objects of known ground-truth shape, determined to within 1% depth accuracy.

Wolff, L.B.; Angelopoulou, E. [Computer Vision Laboratory, Department of Computer Science, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)

1994-11-01

360

Measuring velocity ratios with correlation functions  

NASA Astrophysics Data System (ADS)

We show how to determine the ratio of the transverse velocity of a source to the velocity of emitted particles, using split-bin correlation functions. The technique is to measure S2 and S?2, subtract the contributions from the single-particle distribution, and take the ratio as the bin size goes to zero. We demonstrate the technique for two cases: each source decays into two particles, and each source emits a large number of particles.

Seibert, David; Haglin, Kevin; Gale, Charles

1993-09-01

361

Spectral variability of the particulate backscattering ratio  

NASA Astrophysics Data System (ADS)

The spectral dependency of the particulate backscattering ratio is relevant in the fields of ocean color inversion, light field modeling, and inferring particle properties from optical measurements. Aside from theoretical predictions for spherical, homogeneous particles, we have very limited knowledge of the actual in situ spectral variability of the particulate backscattering ratio. This work presents results from five research cruises that were conducted over a three-year period. Water column profiles of physical and optical properties were conducted across diverse aquatic environments that offered a wide range of particle populations. The main objective of this research was to examine the behavior of the spectral particulate backscattering ratio in situ, both in terms of its absolute magnitude and its variability across visible wavelengths, using over nine thousand 1-meter binned data points for each of five wavelengths of the spectral particulate backscattering ratio. Our analysis reveals no spectral dependence of the particulate backscattering ratio within our measurement certainty, and a geometric mean value of 0.013 for this dataset. This is lower than the commonly used value of 0.0183 from Petzold’s integrated volume scattering data. Within the first optical depth of the water column, the mean particulate backscattering ratio was 0.010.

Whitmire, A. L.; Boss, E.; Cowles, T. J.; Pegau, W. S.

2007-05-01

362

A modification to the fast decoupled power flow for networks with high R\\/X ratios  

Microsoft Academic Search

The reliability of the fast decoupled load-flow method for most power systems is high, but it presents difficulties in convergence for systems with high ratios of branch resistance to reactance. Modifications that retain the advantages of this method but can handle high r\\/x ratios are of interest, and compensation techniques have been used for this purpose. Both the series and

D. Rajicic; A. Bose

1988-01-01

363

Crowding, sex ratio and horn evolution in a South African beetle community  

Microsoft Academic Search

Sexually selected ornaments and weapons are exceptionally variable, even between closely related species. It has long been recognized that some of this diversity can be explained by differences in mating systems between species, but there remains substantial variation between species with similar mating systems. We investigated the roles of sex ratio (measured as operational sex ratio, OSR) and population density

Joanne C. Pomfret; Robert J. Knell

2008-01-01

364

The effect of satellite galaxies on gravitational lensing flux ratios  

NASA Astrophysics Data System (ADS)

Gravitational lenses with anomalous flux ratios are often cited as possible evidence for dark matter satellites predicted by simulations of hierarchical merging in cold dark matter cosmogonies. We show that the fraction of quads with anomalous flux ratios depends primarily on the total mass and spatial extent of the satellites, and the characteristic length-scale d1/2 of their distribution. If d1/2 ~ 100kpc, then for a moderately elliptical galaxy with a line-of-sight velocity dispersion of ~ 250kms-1, a mass of ~3 × 109Msolar in highly concentrated (Plummer model) satellites is needed for 20 per cent of quadruplets to show anomalous flux ratios, rising to ~1.25 × 1010Msolar for 50 per cent. Several times these masses are required if the satellites have more extended Hernquist profiles. Compared to a typical elliptical, the flux ratios of quads formed by typical edge-on disc galaxies with maximum discs are significantly less susceptible to changes through substructure - three times the mass in satellite galaxies is needed to affect 50 per cent of the systems. In many of the lens systems with anomalous flux ratios, there is evidence for visible satellites (e.g. B2045+265 or MG0414+0534). We show that if the anomaly is produced by substructure with properties similar to the simulations, then optically identified substructure should not be preponderant among lens systems with anomalies. There seem to be two possible resolutions of this difficulty. First, in some cases, visible substructure may be projected within or close to the Einstein radius and wrongly ascribed as the culprit, whereas dark matter substructure is causing the flux anomaly. Secondly, bright satellites, in which baryon cooling and condensation have taken place, may have higher central densities than dark satellites, rendering them more efficient at causing flux anomalies.

Shin, E. M.; Evans, N. W.

2008-04-01

365

D/H ratios in meteorites - Some results and implications  

NASA Astrophysics Data System (ADS)

The D/H ratio in carbonaceous chondrites and in highly unequilibrated ordinary chondrites is investigated. The phenomenon of D enrichment in the solar system is discussed, and the results of D/H-ratio studies using different methods are reviewed extensively. The question of the localization of highly D-enriched phases is considered. D/H ratios determined in bulk samples and in HF acid residues after stepwise pyrolysis/oxidation at 200-1000 C are reported for the CM2 meteorite Murchison and the Antarctic meteorite ALHA 77214; bulk-sample stepwise-pyrolysis data are given for the LL3 meteorite Krymka. No relative D enrichment of acid-insoluble phases was detected, and no D-enriched phases were found in the Krymka sample. It is inferred that the lack of isotopic homogenization in H-bearing species D-enriched by ion-molecule reactions in cold interstellar clouds is evidence against extensive thermal processing and hence in favor of a cold-accretion rather than a hot-nebula-condensation model of solar-system formation. Further implications of H/D ratios for cosmogony are suggested.

Fallick, A. E.; Hinton, R. W.; McNaughton, N. J.; Pillinger, C. T.

1983-04-01

366

Resonant recoil in extreme mass ratio binary black hole mergers  

NASA Astrophysics Data System (ADS)

The inspiral and merger of a binary black hole system generally leads to an asymmetric distribution of emitted radiation, and hence a recoil of the remnant black hole directed opposite to the net linear momentum radiated. The recoil velocity is generally largest for comparable mass black holes and particular spin configurations, and approaches zero in the extreme mass ratio limit. It is generally believed that for extreme mass ratios ??1, the scaling of the recoil velocity is |V|??2, where the proportionality coefficient depends on the spin of the larger hole and the geometry of the system (e.g. orbital inclination). The small recoil velocity is due to cancellations; while the fraction of the total binary mass radiated away in gravitational waves is O(?), most of this energy is emitted during the inspiral phase where the momentum radiated integrates to zero over an orbit. Here, we show that for low but nonzero inclination prograde orbits and very rapidly spinning large holes (spin parameter a?>0.9678) the inspiralling binary can pass through resonances where the orbit-averaged radiation-reaction force is nonzero. These resonance crossings lead to a new contribution to the kick, |V|??3/2. For these configurations and sufficiently extreme mass ratios, this resonant recoil is dominant. While it seems doubtful that the resonant recoil will be astrophysically significant, its existence suggests caution when extrapolating the results of numerical kick results to extreme mass ratios and near-maximal spins.

Hirata, Christopher M.

2011-05-01

367

Prosimian Primates Show Ratio Dependence in Spontaneous Quantity Discriminations  

PubMed Central

We directly tested the predictions of the approximate number system (ANS) and the object file system in the spontaneous numerical judgments of prosimian primates. Prior work indicates that when human infants and a few species of non-human animals are given a single-trial choice between two sequentially baited buckets they choose the bucket with the greater amount of food but only when the quantities are small. This pattern of results has been interpreted as evidence that a limited capacity object file system is used to track small numbers of objects and that the ANS is not invoked under these circumstances. Here we tested prosimian primates in food choice comparisons that were chosen to contrast predictions of the ANS and object file systems. We found that prosimian primates consistently chose the larger of two sets when they differed by a 1:3 ratio regardless of whether both values were small (?3), both values were large (>3), or there was one small and one large value. Prosimians were not able to robustly discriminate quantities that differed by a 1:2 ratio for the same three conditions, nor did they show a preference for small quantities that differed by a 2:3 ratio. These results implicate the ANS in the spontaneous numerical discriminations of non-human primates.

Jones, Sarah M.; Brannon, Elizabeth M.

2012-01-01

368

Sex ratio of China's population deserves attention.  

PubMed

A paper on the sex ratio at birth in China was presented at the international seminar on China's 1990 population census held during October 19-23, 1992 in Beijing. The normal sex ratio at birth is 106 male births/100 female births, which was the ratio in China in the 1960s and 1970s. However, in 1981 it increased to 108.5, then to 110.9 in 1986, to 111.0 in 1987, and to 113.8 in 1989. The sex ratios at ages 0-4 years were 107.0 in 1953, 106.2 in 1964, 107.1 in 1982, and 110.2 in 1990. The sex ratio at birth in 1989 was 105 for 1st parity births, but reached 120.9, 124.6, and 131.7 for 2nd, 3rd, 4th and higher parity births, respectively. The analysis of data from the 1990 National Census, the 1987 One Percent Population Sample Survey, and the 1988 Two-Per-Thousand Population Sampling Survey revealed that a serious underreporting of female births and increased illegal prenatal sex identification were the most important causes of the increase in the sex ratio at birth. The sex differential in underreporting births accounted for at least 42.6-51.3% of the difference between the normal value of 106 and the actual sex ratio at birth reported in the 1990 census. Data from the 1988 Two-Per-Thousand Population Sampling Survey showed that rate of underreporting of female births twice exceeded that of male births in the years between 1983 and 1988. The underreporting accounted for 54-88% of the difference between the normal value and the reported sex ratios. A great number of B ultrasonic scanning machines were introduced after 1982 in clinics and family planning service stations. Although they are not meant for nonmedical purposes, enforcement of rules is difficult in view of the preference for sons. Medical records of 1,243,284 pregnancies surveyed for birth defects at 945 hospitals indicated sex ratios of 108.0, 108.3, 109.1, and 109.7 in 1988, 1989, 1990, and 1991, respectively. Underreporting rather than female infanticide is probably the main cause of these increasing sex ratios. Underreporting, however, has detrimental effects on health care and education and creates an unbalanced population sex structure. PMID:12318232

Zeng, Y; Tu, P; Gu, B; Xu, Y; Li, B; Li, Y

1992-12-01

369

Developmental basis of sexually dimorphic digit ratios  

PubMed Central

Males and females generally have different finger proportions. In males, digit 2 is shorter than digit 4, but in females digit 2 is the same length or longer than digit 4. The second- to fourth-digit (2D:4D) ratio correlates with numerous sexually dimorphic behavioral and physiological conditions. Although correlational studies suggest that digit ratios reflect prenatal exposure to androgen, the developmental mechanism underlying sexually dimorphic digit development remains unknown. Here we report that the 2D:4D ratio in mice is controlled by the balance of androgen to estrogen signaling during a narrow window of digit development. Androgen receptor (AR) and estrogen receptor ? (ER-?) activity is higher in digit 4 than in digit 2. Inactivation of AR decreases growth of digit 4, which causes a higher 2D:4D ratio, whereas inactivation of ER-? increases growth of digit 4, which leads to a lower 2D:4D ratio. We also show that addition of androgen has the same effect as inactivation of ER and that addition of estrogen mimics the reduction of AR. Androgen and estrogen differentially regulate the network of genes that controls chondrocyte proliferation, leading to differential growth of digit 4 in males and females. These studies identify previously undescribed molecular dimorphisms between male and female limb buds and provide experimental evidence that the digit ratio is a lifelong signature of prenatal hormonal exposure. Our results also suggest that the 2D:4D ratio can serve as an indicator of disrupted endocrine signaling during early development, which may aid in the identification of fetal origins of adult diseases.

Zheng, Zhengui; Cohn, Martin J.

2011-01-01

370

Intermediate-mass-ratio inspirals in the Einstein Telescope. I. Signal-to-noise ratio calculations  

SciTech Connect

The Einstein Telescope (ET) is a proposed third-generation ground-based interferometric gravitational wave detector, for which the target is a sensitivity that is a factor of 10 better than Advanced LIGO and a frequency range that extends down to {approx}1 Hz. Such a third-generation interferometer will provide opportunities to test Einstein's theory of relativity in the strong field and will realize precision gravitational wave astronomy with a thousandfold increase in the expected number of events over the advanced ground-based detectors. A design study for ET is currently underway, so it is timely to assess the science that could be done with such an instrument. This paper is the first in a series that will carry out a detailed study of intermediate-mass-ratio inspirals (IMRIs) for ET. In the context of ET, an IMRI is the inspiral of a neutron star or stellar-mass black hole into an intermediate mass black hole (IMBH). In this paper we focus on the development of IMRI waveform models for circular and equatorial inspirals. We consider two approximations for the waveforms, which both incorporate the inspiral, merger, and ringdown phases in a consistent way. One approximation, valid for IMBHs of arbitrary spin, uses the transition model of Ori and Thorne [A. Ori and K. S. Thorne, Phys. Rev. D 62, 124022 (2000).] to describe the merger, and this is then matched smoothly onto a ringdown waveform. The second approximation uses the effective one body approach to model the merger phase of the waveform and is valid for nonspinning IMBHs. In this paper, we use both waveform models to compute signal-to-noise ratios for IMRI sources detectable by ET. At a redshift of z=1, we find typical signal-to-noise ratios for IMRI systems with masses 1.4M{sub {center_dot}}+100M{sub {center_dot}}, 10M{sub {center_dot}}+100M{sub {center_dot}}, 1.4M{sub {center_dot}}+500M{sub {center_dot}} and 10M{sub {center_dot}}+500M{sub {center_dot}} of {approx}10-25, {approx}40-80, {approx}3-15, and {approx}10-60, respectively. We also find that the two models make predictions for nonspinning inspirals that are consistent to about 10%.

Huerta, E. A.; Gair, Jonathan R. [Institute of Astronomy, Madingley Road, CB3 0HA Cambridge (United Kingdom)

2011-02-15

371

In vivo dissolution measurement with indium-111 summation peak ratios  

SciTech Connect

Dissolution of (/sup 111/In)labeled tablets was measured in vivo in a totally noninvasive manner by using a modification of the perturbed angular correlation technique known as the summation peak ratio method. This method, which requires the incorporation of only 10-12 microCi into the dosage form, provided reliable dissolution data after oral administration of (/sup 111/In)lactose tablets. These results were supported by in vitro experiments which demonstrated that the dissolution rate as measured by the summation peak ratio method was in close agreement with the dissolution rate of salicylic acid in a (/sup 111/In)salicylic acid tablet. The method has the advantages of using only one detector, thereby avoiding the need for complex coincidence counting systems, requiring less radioactivity, and being potentially applicable to a gamma camera imaging system.

Jay, M.; Woodward, M.A.; Brouwer, K.R.

1985-10-01

372

Development of a Micropyrolyzer for Enhanced Isotope Ratio Measurement  

SciTech Connect

This paper presents design, fabrication and testing of a micro scale reactor for the pyrolysis of organic compounds. The reactor system described here is suitable for use in enhanced isotope ratio measurement in a continuous flow mode. A characteristic of such a system is it can be utilized to pyrolyze organic compounds with sample size 20-50 times smaller than conventional. Results have shown that organic compounds, such as 1-butanol, ethanol, and ethanol amine, can be fully decomposed to desired products CO and H2, at temperature of 1200oC, which is 200oC lower than conventionally reported. Undesired products methane and CO2 are eliminated in the pyrolysis process. The proof-of-concept experimental results clearly demonstrate that the micro pyrolyzer can be readily integrated with isotope ratio mass spectrometer (IRMS) to differentiate between different sources of the same materials.

Hu, Jianli; Dagle, Robert A.; Johnson, Bradley R.; Kreuzer, Helen W.; Gaspar, Daniel J.; Roberts, Benjamin Q.; Alexander, M. L.

2008-11-19

373

Leptin to adiponectin ratio in preeclampsia.  

PubMed

The aim of the present study was to assess leptin/adiponectin ratio in preeclamptic patients compared with normal pregnant women. A cross-sectional study was designed. The study population consisted of 30 preeclamptic patients and 30 healthy pregnant women. Serum levels of total leptin and adiponectin were assessed using commercially available enzyme-linked immunosorbent assay methods. The one-way ANOVA and Student's t tests and Pearson's correlation analysis were used for statistical calculations. Levels of leptin and adiponectin were also adjusted for BMI. A p-value < 0.05 was considered statistically significant. The leptin/adiponectin ratio was increased significantly in preeclamptic patients. The leptin/adiponectin ratio was significantly higher in severe preeclamptic patient than in mild preeclampsia. Adjusted leptin/adiponectin ratio was also significantly increased in preeclamptic patients than in normal pregnant women. The findings of the present study suggest that the leptin/adiponectin ratio was increased in preeclamsia and imbalance between the adipocytokines could be involved in the pathogenesis of preeclampsia. PMID:23923407

Khosrowbeygi, A; Ahmadvand, H

2013-04-01

374

The sex ratio of Plasmodium gametocytes.  

PubMed

Sex ratio theory usually predicts an equilibrium sex ratio and equal proportions of males and females in a population, including the progenitors of the reproductive cells of protozoans. This proposal was tested with three species of malarial parasites of lizards, Plasmodium mexicanum of the western fence lizard, and P. agamae and P. giganteum of the African rainbow lizard, using single samples from naturally infected lizards, repeated samples from free-ranging lizards (P. mexicanum only), and repeated samples from laboratory maintained animals. Macrogametocytes were usually more abundant than microgametocytes, and were slightly larger, revealing a typically greater investment of resources by the progenitors of female reproductive cells. However, the proportion of microgametocytes varied among the three species and among infections within each species of Plasmodium. The sex ratio of gametocytes often remained constant within infections followed over time even if the absolute number of gametocytes was changing. However, the equilibrium sex ratio of gametocytes varied among those infections that had an unchanging microgametocyte proportion. Thus, although an equilibrium sex ratio apparently occurs for most infections, there appears to be no characteristic proportion of microgametocytes for any of the species. Potential explanations for this conflict with theory are presented. PMID:2771445

Schall, J J

1989-06-01

375

The 240Pu/239Pu ratio, a potential geochronometer  

NASA Astrophysics Data System (ADS)

The Arctic and Antarctic ice sheets maintain records of the atmospheric fallout in their datable strata. The 240Pu 239Pu ratios in these polar reservoirs uniquely distinguish particulate fallout from the pre-moratorium nuclear atmospheric weapons tests, dominated by the U.S., and the post-moratorium atmospheric weapons tests, dominated by the U.S.S.R. Thus, they offer the possibility of use as a geochronological tool for some marine, glacial, lacustrine and soil systems.

Koide, Minoru; Bertine, Kathe K.; Chow, Tsaihwa J.; Goldberg, Edward D.

1985-01-01

376

A measurement of the inclusive b-->s? branching ratio  

NASA Astrophysics Data System (ADS)

The flavour changing neutral current decay b-->s? has been detected in hadronic Z decays collected by ALEPH at LEP. The signal is isolated in lifetime-tagged bb¯ events by the presence of a hard photon associated with a system of high momentum and high rapidity hadrons. The background processes are normalised from the data themselves. The inclusive branching ratio is measured to beconsistent with the Standard Model expectation via penguin processes. © 1998

ALEPH Collaboration; Barate, R.; Buskulic, D.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Merle, E.; Minard, M.-N.; Nief, J.-Y.; Pietrzyk, B.; Alemany, R.; Boix, G.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Graugès, E.; Juste, A.; Martinez, M.; Merino, G.; Miquel, R.; Mir, Ll. M.; Park, I. C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Becker, U.; Bright-Thomas, P.; Casper, D.; Cattaneo, M.; Ciulli, V.; Dissertori, G.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Hansen, J. B.; Harvey, J.; Janot, P.; Jost, B.; Lehraus, I.; Mato, P.; Minten, A.; Moneta, L.; Pacheco, A.; Pusztaszeri, J.-F.; Ranjard, F.; Rolandi, L.; Rousseau, D.; Schlatter, D.; Schmitt, M.; Schneider, O.; Tejessy, W.; Teubert, F.; Tomalin, I. R.; Wachsmuth, H.; Ajaltouni, Z.; Badaud, F.; Chazelle, G.; Deschamps, O.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Siotis, I.; Vayaki, A.; Blondel, A.; Bonneaud, G.; Brient, J.-C.; Bourdon, P.; Rougé, A.; Rumpf, M.; Valassi, A.; Verderi, M.; Videau, H.; Focardi, E.; Parrini, G.; Zachariadou, K.; Corden, M.; Georgiopoulos, C.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Halley, A. W.; Lynch, J. G.; Negus, P.; O'Shea, V.; Raine, C.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, E.; Buchmüller, O.; Dhamotharan, S.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Goodsir, S.; Martin, E. B.; Marinelli, N.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Spagnolo, P.; Williams, M. D.; Ghete, V. M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Buck, P. G.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Robertson, N. A.; Sloan, T.; Williams, M. I.; Giehl, I.; Greene, A. M.; Hoffmann, C.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Carr, J.; Coyle, P.; Etienne, F.; Leroy, O.; Motsch, F.; Payre, P.; Talby, M.; Sadouki, A.; Thulasidas, M.; Trabelsi, K.; Aleppo, M.; Antonelli, M.; Ragusa, F.; Berlich, R.; Blum, W.; Büscher, V.; Dietl, H.; Ganis, G.; Kroha, H.; Lütjens, G.; Mannert, C.; Männer, W.; Moser, H.-G.; Schael, S.; Settles, R.; Seywerd, H.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Chen, S.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Schune, M.-H.; Tournefier, E.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Batignani, G.; Bettarini, S.; Boccali, T.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; dell'Orso, R.; Fantechi, R.; Ferrante, I.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Sciabà, A.; Sguazzoni, G.; Tenchini, R.; Tonelli, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Bryant, L. M.; Chambers, J. T.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Johnson, R. P.; Kim, H. Y.; Konstantinidis, N.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Kelly, M. S.; Lehto, M.; Reeve, J.; Thompson, L. F.; Affholderbach, K.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Saraiva, P.; Smolik, L.; Stephan, F.; Giannini, G.; Gobbo, B.; Musolino, G.

1998-06-01

377

Dynamic tracking of page miss ratio curve for memory management  

Microsoft Academic Search

Memory can be efficiently utilized if the dynamic memory demands of applications can be determined and analyzed at run-time. The page miss ratio curve(MRC), i.e. page miss rate vs. memory size curve, is a good performance-directed metric to serve this purpose. However, dynamically tracking MRC at run time is challenging in systems with virtual memory because not every memory reference

Pin Zhou; Vivek Pandey; Jagadeesan Sundaresan; Anand Raghuraman; Yuanyuan Zhou; Sanjeev Kumar

2004-01-01

378

Roof–envelope ratio impact on green roof energy performance  

Microsoft Academic Search

This paper addresses the impact of roof-to-envelope ratio on overall energy savings of a green roof design over conventional\\u000a roof designs. Simulations were performed using a modified version of the Environmental System Performance program simulator,\\u000a developed at the University of Strathclyde. The modified design employed a model developed by Columbia University and the\\u000a Goddard Institute of Space Science which models

Ryan Martens; Brad Bass; Susana Saiz Alcazar

2008-01-01

379

A snail with unbiased population sex ratios but highly biased brood sex ratios.  

PubMed

Extraordinary sex ratio patterns and the underlying sex-determining mechanisms in various organisms are worth investigating, particularly because they shed light on adaptive sex-ratio adjustment. Here, we report an extremely large variation in the brood sex ratio in the freshwater snail, Pomacea canaliculata. In eight rearing series originating from three wild populations, sex ratios were highly variable among broods, ranging continuously from almost exclusively males to almost exclusively females. However, sex ratios were similar between broods from the same mating pair, indicating that sex ratio is a family trait. Irrespective of the large variations, the average sex ratios in all rearing series were not significantly different from 0.5. We argue that Fisher's adaptive sex-ratio theory can explain the equal average sex ratios, and the results, in turn, directly support Fisher's theory. Polyfactorial sex determination (in which sex is determined by three or more genetic factors) is suggested as the most likely mechanism producing the variable brood sex ratio. PMID:12614578

Yusa, Yoichi; Suzuki, Yoshito

2003-02-01

380

Kinship Institutions and Sex Ratios in India  

PubMed Central

This article explores the relationship between kinship institutions and sex ratios in India at the turn of the twentieth century. Because kinship rules vary by caste, language, religion, and region, we construct sex ratios by these categories at the district level by using data from the 1901 Census of India for Punjab (North), Bengal (East), and Madras (South). We find that the male-to-female sex ratio varied positively with caste rank, fell as one moved from the North to the East and then to the South, was higher for Hindus than for Muslims, and was higher for northern Indo-Aryan speakers than for the southern Dravidian-speaking people. We argue that these systematic patterns in the data are consistent with variations in the institution of family, kinship, and inheritance.

CHAKRABORTY, TANIKA; KIM, SUKKOO

2010-01-01

381

AR XIII line ratios in solar flares  

NASA Astrophysics Data System (ADS)

Theoretical Ar XIII electron-density-sensitive emission line ratios, derived using electron impact excitation rates interpolated from accurate R-matrix calculations, are presented for R1 = I/(242.22 A)/I(236.27 A), R2 = I(210.46 A)/I(236.27 A), and R3 = I/(248.68 A)/I(236.27 A). Electron densities deduced from the observed values of R1, R2, and R3 for solar flares obtained with the NRL S082A slitless spectrograph on board Skylab are in excellent agreement, and furthermore compare favorably with those determined from line ratios in Ca XV, which is formed at a similar electron temperature to that of Ar XIII. These results provide experimental support for the accuracy of the atomic data adopted in the analysis, as well as for the techniques used to calculate the line ratios.

Keenan, F. P.; Conlon, E. S.; Foster, V. J.; Aggarwal, K. M.; Widing, K. G.

1993-06-01

382

Ratio vectors of fourth degree polynomials  

NASA Astrophysics Data System (ADS)

Let p(x) be a polynomial of degree 4 with four distinct real roots r1ratios , k=1,2,3. For notational convenience, let [sigma]1=u, [sigma]2=v, and [sigma]3=w. (u,v,w) is called the ratio vector of p. We prove necessary and sufficient conditions for (u,v,w) to be a ratio vector of a polynomial of degree 4 with all real roots. Most of the necessary conditions were proven in an earlier paper. The main results of this paper involve using the theory of Groebner bases to prove that those conditions are also sufficient.

Horwitz, Alan

2006-01-01

383

Kinship institutions and sex ratios in India.  

PubMed

This article explores the relationship between kinship institutions and sex ratios in India at the turn of the twentieth century. Because kinship rules vary by caste, language, religion, and region, we construct sex ratios by these categories at the district level by using data from the 1901 Census of India for Punjab (North), Bengal (East), and Madras (South). We find that the male-to-female sex ratio varied positively with caste rank, fell as one moved from the North to the East and then to the South, was higher for Hindus than for Muslims, and was higher for northern Indo-Aryan speakers than for the southern Dravidian-speaking people. We argue that these systematic patterns in the data are consistent with variations in the institution of family, kinship, and inheritance. PMID:21308567

Chakraborty, Tanika; Kim, Sukkoo

2010-11-01

384

Magnetostrictive contribution to Poisson ratio of galfenol  

NASA Astrophysics Data System (ADS)

In this work we present a detailed study on the magnetostrictive contribution to Poisson ratio for samples under applied mechanical stress. Magnetic contributions to strain and Poisson ratio for cubic materials were derived by accounting elastic and magneto-elastic anisotropy contributions. We apply our theoretical results for a material of interest in magnetomechanics, namely, galfenol (Fe1-xGax). Our results show that there is a non-negligible magnetic contribution in the linear portion of the curve of stress versus strain. The rotation of the magnetization towards [110] crystallographic direction upon application of mechanical stress leads to an auxetic behavior, i.e., exhibiting Poisson ratio with negative values. This magnetic contribution to auxetic behavior provides a novel insight for the discussion of theoretical and experimental developments of materials that display unusual mechanical properties.

Paes, V. Z. C.; Mosca, D. H.

2013-09-01

385

Anomalous nitrogen isotope ratio in comets.  

PubMed

High-resolution spectra of the CN B2 summation operator +-X2 summation operator + (0,0) band at 390 nanometers yield isotopic ratios for comets C/1995 O1 (Hale-Bopp) and C/2000 WM1 (LINEAR) as follows: 165 +/- 40 and 115 +/- 20 for 12C/13C, 140 +/- 35 and 140 +/- 30 for 14N/15N. Our N isotopic measurements are lower than the terrestrial 14N/15N = 272 and the ratio for Hale-Bopp from measurements of HCN, the presumed parent species of CN. This isotopic anomaly suggests the existence of other parent(s) of CN, with an even lower N isotopic ratio. Organic compounds like those found in interplanetary dust particles are good candidates. PMID:12970562

Arpigny, Claude; Jehin, Emmanuël; Manfroid, Jean; Hutsemékers, Damien; Schulz, Rita; Stüwe, J A; Zucconi, Jean-Marc; Ilyin, Ilya

2003-09-12

386

Fluctuating silicate:nitrate ratios and coastal plankton food webs  

PubMed Central

Marine diatoms require dissolved silicate to form an external shell, and their growth becomes Si-limited when the atomic ratio of silicate to dissolved inorganic nitrogen (Si:DIN) approaches 1:1, also known as the “Redfield ratio.” Fundamental changes in the diatom-to-zooplankton-to-higher trophic level food web should occur when this ratio falls below 1:1 and the proportion of diatoms in the phytoplankton community is reduced. We quantitatively substantiate these predictions by using a variety of data from the Mississippi River continental shelf, a system in which the Si:DIN loading ratio has declined from around 3:1 to 1:1 during this century because of land-use practices in the watershed. We suggest that, on this shelf, when the Si:DIN ratio in the river decreases to less than 1:1, then (i) copepod abundance changes from >75% to <30% of the total mesozooplankton, (ii) zooplankton fecal pellets become a minor component of the in situ primary production consumed, and (iii) bottom-water oxygen consumption rates become less dependent on relatively fast-sinking (diatom-rich) organic matter packaged mostly as zooplankton fecal pellets. This coastal ecosystem appears to be a pelagic food web dynamically poised to be either a food web composed of diatoms and copepods or one with potentially disruptive harmful algal blooms. The system is directed between these two ecosystem states by Mississippi River water quality, which is determined by land-use practices far inland.

Turner, R. Eugene; Qureshi, Naureen; Rabalais, Nancy N.; Dortch, Quay; Justic, Dubravko; Shaw, Richard F.; Cope, Joseph

1998-01-01

387

Radioactive anomaly discrimination from spectral ratios  

DOEpatents

A method for discriminating a radioactive anomaly from naturally occurring radioactive materials includes detecting a first number of gamma photons having energies in a first range of energy values within a predetermined period of time and detecting a second number of gamma photons having energies in a second range of energy values within the predetermined period of time. The method further includes determining, in a controller, a ratio of the first number of gamma photons having energies in the first range and the second number of gamma photons having energies in the second range, and determining that a radioactive anomaly is present when the ratio exceeds a threshold value.

Maniscalco, James; Sjoden, Glenn; Chapman, Mac Clements

2013-08-20

388

Perceived night length ratios in ancient Egypt  

NASA Astrophysics Data System (ADS)

The first record we have of a seasonal night length ratio for Egypt is from the mid 16th century BC. The origin of this estimate is traced to observations made three centuries previously, and the later reinterpretation and instrumental use of this ratio is traced down to 100AD. Extended comment is made on the astronomical dating involved in this description of events, and an attempt is made to reconstruct the alleged confirmation (or calibration) of the new timepiece that plays a central part in the story. It is believed that this is the earliest example of this fundamental scientific practice on record.

Fermor, John

389

Branching Ratios for K+-->3pi Decays  

Microsoft Academic Search

The branching ratios tau'+(K+-->all) and tau'+tau+ were obtained from a sample of 12 976K+ decays including 198 tau'+ and 693tau+ decays. It was found that tau'+(K+-->all)=0.0153+\\/-0.0011, and that tau'+tau+=0.286+\\/-0.023. The tau+(K+-->all) branching ratio and the pi+ energy spectrum in tau'+ decay were also obtained, and were found to be in good agreement with the more precise determinations of the other

D. Pandoulas; S. Taylor; E. L. Koller; J. Grauman; S. Hoffmaster; O. Raths; L. Romano; P. Stamer

1970-01-01

390

Homomorphic processing system and ratio rule for color image enhancement  

Microsoft Academic Search

Homomorphic filter is an illumination-reflectance model that can be used to develop a frequency domain procedure for improving the appearance of an image by simultaneous gray-level range compression and contrast enhancement. Many previously reported methods on homomorphic filter for color images shows that the homomorphic filter consistently provides excellent dynamic range compression but is lacking final color rendition. We present

Ming-Jung Seow; Vijayan K. Asari

2004-01-01

391

Pancake shaped micro gear system with high transmission ratio  

Microsoft Academic Search

Within the last five years micro motors with dimensions in the millimeter range have been established for a large variety of applications. Usually, a gear is necessary to adapt the motor to the users requirements. Suitable gears for micro motors of the longish type are already commercially available. On the other hand there are applications which need very flat actuators.

R. Degen; W. Ehrfeld; F. Michel

392

Aspect-ratio-controlled synthesis of high-aspect-ratio gold nanorods in high-yield  

Microsoft Academic Search

We describe a modified seed-mediated synthesis of high-aspect-ratio gold nanorods controlling the aspect ratio with variation of pH in the growth solution. By adding various amounts of sodium hydroxide, pH in the growth solution was controlled from 1.29 to 7.06 in the presence of nitrate anions. At various pH of the growth solution, the yield of high-aspect-ratio gold nanorods was

Won Min Park; Yun Suk Huh; Won Hi Hong

2009-01-01

393

Utilizing Isotopic Uranium Ratios in Groundwater Evaluations at NFSS  

SciTech Connect

The U.S. Army Corps of Engineers (USACE) Buffalo District is currently evaluating environmental contamination at the Niagara Falls Storage Site (NFSS) under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) as part of its Formerly Utilized Sites Remedial Action Program (FUSRAP). The NFSS is located in the Town of Lewiston in western New York and has been used to store uranium-contaminated materials since 1944. Most of the radioactive materials are currently contained in an on-site structure, but past contamination remains in soil and groundwater. As a naturally occurring radionuclide, uranium is present in all groundwater. Because contamination levels at the site are quite low, it can be difficult to distinguish zones that have been impacted by the past releases from those at the high end of the natural background range. The differences in the isotopic ratio of uranium-234 (U-234) to uranium-238 (U-238) between natural groundwater systems and affected areas are being used in an innovative way to better define the nature and extent of groundwater contamination at NFSS. In natural groundwater, the ratio of U-234 to U-238 exceeds 1 due to the alpha particle recoil effect, in which U-234 is preferentially mobilized to groundwater from adjacent rock or soil. This process is very slow, and it can be hundreds to thousands of years before a measurable impact is seen in the isotopic ratio. Thus, as a result of the recoil effect, the ratio of U-234 to U-238 will be higher in natural groundwater than in contaminated groundwater. This means that if site releases were the source of the uranium being measured in groundwater at NFSS, the ratio of U-234 to U-238 would be expected to be very close to 1 (the same ratio that exists in wastes and soil at the site), because not enough time has elapsed for the alpha particle recoil effect to have significantly altered that ratio. From an evaluation of site and regional groundwater data, an isotopic ratio of 1.2 has been identified as a site-specific signature to help distinguish natural groundwater (e.g., at the high end of the background range) from zones impacted by past releases. This information is crucial for focusing the ongoing CERCLA evaluation and decision making process. This signature value is not applied as a bright line, e.g., to define samples with ratios of U-234 to U-238 above 1.2 as representing background and those with ratios below 1.2 as being affected by site releases. Rather, this ratio serves as a weight of evidence for use in conjunction with other site information, including historical activities, to form science-based decisions regarding contaminated groundwater. This novel approach for developing a groundwater signature from the isotopic uranium ratio has proven to be a very useful tool for NFSS, and it is now being considered for broader application. (authors)

Rhodes, M.C.; Keil, K.G.; Frederick, W.T.; Papura, T.R.; Leithner, J.S. [U.S. Army Corps of Engineers, Buffalo District, 1776 Niagara Street, Buffalo, NY 14207 (United States); Peterson, J.M.; MacDonell, M.M. [Argonne National Laboratory, Environmental Science Division, 9700 South Cass Avenue, Building 900, Argonne, IL 60439 (United States)

2006-07-01

394

Disproportionate sex ratios of wolf pups  

USGS Publications Warehouse

Males comprised 66 percent of wild wolf (Canis lupus) pups from a saturated, high-density wolf range in northeastern Minnesota, possibly reflecting disproportionate conception of males. Packs from areas of lower wolf density in other areas of Minnesota had equal sex ratios of pups or a disproportionate number of female pups. Captive wolves showed a slight preponderance of male pups.

Mech, L.D.

1975-01-01

395

Negative Poisson's ratios in cellular foam materials  

Microsoft Academic Search

Materials with negative Poisson's ratios (auxetic) get fatter when stretched and thinner when compressed. This paper discusses a new explanation for achieving auxetic behaviour in foam cellular materials, namely a ‘rotation of rigid units’ mechanism. Such auxetic cellular materials can be produced from conventional open-cell cellular materials if the ribs of cell are slightly thicker in the proximity of the

Joseph N. Grima; Ruben Gatt; Naveen Ravirala; Andrew Alderson; K. E. Evans

2006-01-01

396

Male pygmy hippopotamus influence offspring sex ratio.  

PubMed

Pre-determining fetal sex is against the random and equal opportunity that both conceptus sexes have by nature. Yet, under a wide variety of circumstances, populations shift their birth sex ratio from the expected unity. Here we show, using fluorescence in situ hybridization, that in a population of pygmy hippopotamus (Choeropsis liberiensis) with 42.5% male offspring, males bias the ratio of X- and Y-chromosome-bearing spermatozoa in their ejaculates, resulting in a 0.4337±0.0094 (mean±s.d.) proportion of Y-chromosome-bearing spermatozoa. Three alternative hypotheses for the shifted population sex ratio were compared: female counteract male, female indifferent, or male and female in agreement. We conclude that there appears little or no antagonistic sexual conflict, unexpected by prevailing theories. Our results indicate that males possess a mechanism to adjust the ratio of X- and Y-chromosome-bearing spermatozoa in the ejaculate, thereby substantially expanding currently known male options in sexual conflict. PMID:22426218

Saragusty, Joseph; Hermes, Robert; Hofer, Heribert; Bouts, Tim; Göritz, Frank; Hildebrandt, Thomas B

2012-02-28

397

Net energy ratio of photobiohydrogen generation  

Microsoft Academic Search

We estimate the energy content, the operational energy inputs, and the net energy ratio (NER) of an industrial tubular photobioreactor used for the photosynthetic production of H2 by microalgae. The calculated H2 output of the photobioreactor is based on a range of algal photosynthetic H2 generation efficiencies, and on the application of standard theory for tubular solar collectors. Small diameter

G. Burgess; J. G. Fernández-Velasco

398

Space Elevator Ribbon Mass and Taper Ratio  

Microsoft Academic Search

Assumptions about tensile strength and density aect the space elevator ribbon taper ratio, and therefore its mass. We examine the technical trade-os between material properties and total mass of a modern space elevator ribbon, and the economic trade-os between ribbon mass, the number of rocket launches required to loft the initial ribbon, and the time required to build the ribbon

Tom Nugent

399

Generalized golden ratios of ternary alphabets  

Microsoft Academic Search

Expansions in noninteger bases often appear in number theory and probability theory, and they are closely connected to ergodic theory, measure theory and topology. For two-letter alphabets the golden ratio plays a special role: in smaller bases only trivial expansions are unique, whereas in greater bases there exist nontrivial unique expansions. In this paper we determine the corresponding critical bases

Vilmos Komornik; Anna Chiara Lai; Marco Pedicini

2009-01-01

400

Dynamic Programming creates The Golden Ratio, too  

Microsoft Academic Search

Since ancient times of Greek as the Parthenon at Athens, the Golden Ratio has been keeping to give a profound influence in many various fields. Mathematicians love the number to explain the nature of the universe and of human life. It comes up even with a formula for the human de- cision making process; aesthetics, etc. Also in the typical

Seiichi Iwamoto; Masami Yasuda

401

Optimal Aspect Ratio for 3D TV  

Microsoft Academic Search

Various types of 3D display technologies have been developed over the past decade. However the problem of how the aspect ratio of 3D display devices should be determined has received limited attention. Displays are often determined by industry and international standards, and do not take the 3D scene properties and depth perception into account. In this work we investigate the

Irene Cheng; Anup Basu

2007-01-01

402

Sex-ratio variation in Soay sheep  

Microsoft Academic Search

We studied the effects of ecological variables on the birth sex ratio of Soay sheep (Ovis aries) lambs on the island of Hirta, in the St Kilda archipelago, Scotland. Both individual- and population-level models were constructed. In the individual-based model, only population size was significantly associated with the sex of a lamb, with the probability of giving birth to a

Jan Lindström; Tim Coulson; Loeske Kruuk; Mads C. Forchhammer; Dave W. Coltman; Tim Clutton-Brock

2002-01-01

403

Giving More Realistic Definitions of Trigonometric Ratios  

ERIC Educational Resources Information Center

|Trigonometry is a well known branch of Mathematics. The study of trigonometry is of great importance in surveying, astronomy, navigation, engineering, and in different branches of science. This paper reports on the discovery of flaws in the traditional definitions of trigonometric ratios of an angle, which (in most cases) make use of the most…

Bhattacharjee, Pramode Ranjan

2012-01-01

404

Perspectives on the basic reproductive ratio  

Microsoft Academic Search

The basic reproductive ratio, R0, is defined as the expected number of secondary infections arising from a single individual during his or her entire infectious period, in a population of susceptibles. This concept is fundamental to the study of epidemiology and within-host pathogen dynamics. Most importantly, R0 often serves as a threshold parameter that predicts whether an infection will spread.

J. M. Heffernan; R. J. Smith; L. M. Wahl

2005-01-01

405

Branching ratios of b-flavored mesons  

SciTech Connect

The branching ratios of b-flavored mesons are investigated in a dynamical framework based on current algebra modified for the meson moment dependence. Matrix elements are calculated using quark models. A comparison is made with results obtained in separable approximation.

Fajfer, S.; Tadic, D.

1986-02-01

406

Ratio Analysis in Higher Education: Caveat Emptor.  

ERIC Educational Resources Information Center

|Ratio analyses are useful, but care must be taken not to overstate their importance or disregard their limitations. Internally designated, nonstandardized recording techniques in interinstitutional comparisons, inflationary distortions in internal analysis, and judgments made on trends can obstruct the manager's efforts to assess a higher…

DiSalvio, Philip

1989-01-01

407

Sports Classification Using Cross-Ratio Histograms  

Microsoft Academic Search

Abstract. The paper proposes a novel approach for classiflcation of sports images based on the geometric information encoded in the image of a sport’s fleld. The proposed approach uses invariant nature of a crossratio under projective transformation to develop a robust classifler. For a given image, cross-ratios are computed for the points obtained from the intersection of lines detected using

Balamanohar Paluri; S. Nalin Pradeep; Hitesh Shah; C. Prakash

2007-01-01

408

An Experiment in Teaching Ratio and Proportion  

ERIC Educational Resources Information Center

|This paper summarizes our analysis of the complexity of ratio problems at Grades 6 and 7, and reports a two-year experiment related to the teaching and learning of rational numbers and proportionality in these grades. Two classes were followed and observed. Part of the teaching material was common to both classes, mainly the objectives and the…

Adjiage, Robert; Pluvinage, Francois

2007-01-01

409

Conditioning Ratio Estimates under Simple Random Sampling  

Microsoft Academic Search

The usual ratio estimates for a population mean use information on an auxiliary variable to improve the estimation. The standard randomization analysis, however, does not take enough account of the observations on the auxiliary variable, so estimates and estimated variates can be conditionally biased unless the sample is balanced with respect to the auxiliary variable. I propose a method of

J. Robinson

1987-01-01

410

Sex ratios: human twins and fraternal effects.  

PubMed

Historical data from Finnish populations reveals that, for females, exposure to a male twin in the womb may have significant, life-long, effects on subsequent fitness, with profound implications for the evolution of sex ratios and brood size. PMID:17878048

Knowles, Sarah C L; Sheldon, Ben C

2007-09-18

411

IC test using the energy consumption ratio  

Microsoft Academic Search

Dynamic-current based test techniques can potentially address the drawbacks of traditional and Iddq test methodologies. The qual- ity of dynamic current based test is degraded by process variations in IC manufacture. The energy consumption ratio (ECR) is a new metric that improves the effectiveness of dynamic current test by reducing the impact of process variations by an order of magni-

Wanli Jiang; Bapiraju Vinnakota

1999-01-01

412

Ranking fuzzy numbers by preference ratio  

Microsoft Academic Search

We propose a ranking method for fuzzy numbers. In this method a preference function is defined by which fuzzy numbers are measured point by point and at each point the most preferred number is identified. Then, these numbers are ranked on the basis of their preference ratio. Therefore, fuzzy numbers are compared relatively and not necessarily one is preferred absolutely

Mohammad Modarres; Soheil Sadi-nezhad

2001-01-01

413

Priors and Likelihood Ratios as Evidence  

Microsoft Academic Search

Arguments based on diagnostic data concerning a particular case, and ones based on prior experience with like cases, can be represented by belief functions and combined by Dempster's Rule. In limiting cases, the belief functions depend on likelihood ratio or on prior odds, and when these limiting cases occur together, Bayes' Theorem is applicable as is Dempster's Rule. The resulting

David H. Krantz; John Miyamoto

1983-01-01

414

Dynamic orientation ratio in longitudinal recording media  

Microsoft Academic Search

The origin of orientation ratio (OR) in longitudinal recording media has been controversial in the literature. In the past, the observation of a higher OR for thinner magnetic films has been attributed to stress or thermal effects. Our measurements, carried out over a larger range of time scales, confirm that the thermal effects play a major role in the observation

S. N. Piramanayagam; J. H. Yin; H. B. Zhao; J. Kasim; Y. J. Chen; J. Zhang; C. H. Hee

2003-01-01

415

Shape from Photometric Ratio and Stereo  

Microsoft Academic Search

Based on the traditional problem formulation, it is difficult to integrate the two important vision cues, i.e., shading and stereo, for shape reconstruction due to conflicting albedo and image projection assumptions. In this research, we propose a novel scheme to integrate shading and stereo. First, by using the photometric ratio, we derive a new SFS (shape from shading) formulation where

Kyoung Mu Lee; C.-C. Jay Kuo

1996-01-01

416

Ratio, Proportion and Scaling. Mathematics Resource Project.  

ERIC Educational Resources Information Center

|The Mathematics Resource Project has as its goal the production of topical resources for teachers, drawn from the vast amounts of available material. This experimental edition on Ratio, Proportion, and Scaling, contains a teaching emphasis section, a classroom materials section, and teacher commentaries. The teaching emphasis section stresses…

Hoffer, Shirley Ann, Ed.

417

Ratio of Specific Heats of Gases  

NSDL National Science Digital Library

Students bounce a steel ball in a gas-filled tube. The compressed gas provides a restoring force on the ball. By measuring the distance of initial fall or the frequency of oscillation, the ratio of specific heats of several gases, Cp/Cv may be determined.

2009-02-16

418

Optimum phase ratio in the triple jump  

Microsoft Academic Search

The purpose of this study was to develop and validate a method to determine the optimum phase ratio that yields the longest actual distance for a given triple jumper. Two hypotheses were tested: (a) for any given triple jumper, the greater the gain in the vertical velocity the greater the loss in the horizontal velocity; and (b) there is no

Bing Yu; James G. Hay

1996-01-01

419

Ratio method of measuring $w$ boson mass  

SciTech Connect

This dissertation describes an alternative method of measuring the W boson mass in D0 experiment. Instead of extracting M{sub W} from the fitting of W {yields} e{nu} fast Monte Carlo simulations to W {yields} e{nu} data as in the standard method, we make the direct fit of transverse mass between W {yields} e{nu} data and Z {yields} ee data. One of the two electrons from Z boson is treated as a neutrino in the calculation of transverse mass. In ratio method, the best fitted scale factor corresponds to the ratio of W and Z boson mass (M{sub W}/M{sub Z}). Given the precisely measured Z boson mass, W mass is directly fitted from W {yields} e{nu} and Z {yields} ee data. This dissertation demonstrates that ratio method is a plausible method of measuring the W boson mass. With the 1 fb{sup -1} D0 Run IIa dataset, ratio method gives M{sub W} = 80435 {+-} 43(stat) {+-} 26(sys) MeV.

Guo, Feng; /SUNY, Stony Brook

2010-08-01

420

BEHR: Bayesian Estimation of Hardness Ratios  

NASA Astrophysics Data System (ADS)

BEHR is a standalone command-line C program designed to quickly estimate the hardness ratios and their uncertainties for astrophysical sources. It is especially useful in the Poisson regime of low counts, and computes the proper uncertainty regardless of whether the source is detected in both passbands or not.

Park, T.; Kashyap, V. L.; Siemiginowska, A.; van Dyk, D.; Zezas, A.; Heinke, C.; Wargelin, B. J.

2013-06-01

421

Carbon\\/Nitrogen Ratios in Cacao Soils  

Microsoft Academic Search

BY tabulating and comparing the results of a detailed laboratory examination of profile samples of cacao soils collected in January 1930, in the island of Tobago, British West Indies, one of us (G. G.) was able to demonstrate 1 a close correlation between the yielding capacity and the carbon\\/nitrogen ratio for the organic matter contained in the surface six-inch layer

F. Hardy; G. Griffith

1932-01-01

422

Low Poisson Ratios in Subduction Zones  

NASA Astrophysics Data System (ADS)

The growing capability to measure seismic velocities in subduction zones has led to an unusual observation: VP/VS ratios as low as 1.65 with VS ~ 4.7 km/s. This is difficult to explain because most minerals have VP/VS ratios exceeding 1.75, and some of the likely alteration phases, like antigorite, clinohumite and chlorite have high VP/VS ratios. Here we explore how these unusually low VP/VS ratios might be produced, using three methods. 1. Velocity anisotropy was calculated for deformed peridotite, using the Christoffel equation and crystal preferred orientations (CPOs) reported in the literature. Peridotite with ‘Type-A’ olivine CPOs can reproduce the observed values for VP/VS1, but not VP/VS2, and only at temperatures <1000°C; other types of olivine CPOs yield VP/VS1 > 1.73. Anisotropy may be effective in situations where measurements of Vs are dominated by the fast, first-arriving signal, as may be the case in some local tomography studies. 2. Isotropic velocities were calculated for rocks other than peridotite. Although the presence of free quartz produces low VP/VS, it requires extensive SiO2 metasomatism, produces rocks too buoyant to remain in the wedge, is stable only over a narrow 1000-1342°C temperature interval at 3 GPa, and yields VS that are too slow. Brucite and talc are also too slow. Less SiO2 metasomatism produces orthopyroxene, and this yields peridotite with appropriate VP/VS ratios, but only at 600-900°C and only for pure enstatite, not the Mg# 93-95 expected. 3. Mineralogy was calculated as a function of P & T for a range of rock compositions (including metasomatized peridotite, igneous rocks, and sediment) using Perple_X, and velocity anisotropy calculations were made using the Christoffel equation and typical crystal preferred orientations for the constituent phases. Metasomatized mantle containing talc can produce the appropriate VP/VS ratios and VS at 600°C as can mantle with mica + amphibole + pyroxene at 800°C. At 1000°C, no calculated velocities were found that match those observed. Thus, the unusually low VP/VS ratios observed in some subduction zones can be explained as the result of metasomatized peridotite with “Type-A” olivine CPOs at temperatures <1000°C.

Hacker, B. R.; Abers, G. A.

2010-12-01

423

Understanding intrinsic ductility from Poisson's ratio for amorphous solids through force-field tuning  

NASA Astrophysics Data System (ADS)

This work is motivated by recently observed empirical relationship between the Poisson's ratio and the fracture energy for a range of metallic glasses and oxide glasses. Glassy solids with low Poisson's ratio are brittle and vice versa, with a critical Poisson's ratio of about 0.31. Here we used a force-field tuning scheme to investigate how a near-equilibrium elastic constant determines far-from-equilibrium fracture behavior. By modifying a well-studied binary Lennard-Jones system, we obtained a family of glassy systems with different Poisson's ratio ranging from 0.2 to 0.4. Interestingly, the model glasses with low Poisson's ratio exhibit brittle fracture in tension and vice versa, which agrees with experimental observations. Finally, we will discuss how ductility of amorphous solids can be comprehended in terms of the structure and bonding of the amorphous solids, both of which also dictate the Poisson's ratio.

Shi, Yunfeng; Luo, Jian

2011-03-01

424

Nonuniversal lower bound for the shear viscosity to entropy density ratio  

SciTech Connect

The lower bound of the shear viscosity to entropy density ratio is examined using an exact representation of the ratio through the density of states. Under certain assumptions it can be shown that the lower bound of the ratio is not universal; its value is determined by the entropy density. Some examples of physical systems are discussed in the paper where one can expect violation of the conformal 1/4{pi} value.

Jakovac, Antal [Physics Institute, BME Technical University, H-1111 Budapest (Hungary)

2010-02-15

425

PERFORMANCE OF SMART ANTENNA ARRAYS WITH MAXIMAL-RATIO EIGEN-COMBINING  

Microsoft Academic Search

Conventionally, maximum average signal-to-noise ratio beamforming (Max-ASNR BF) and maximal-ratio combining (MRC) are applied to antenna array systems. A recently-proposed com-bining approach based on the Karhunen-Lo`eve Transform (KLT) followed by MRC of the strongest resultant signals, denoted herein as maximal-ratio eigen-beamforming (MREC), was claimed to be superior and flexible compared to Max-ASNR BF and MRC for correlated, imperfectly-estimated channels, but

Constantin Siriteanu; Steven D. Blostein

426

Continuous measurements of methane mixing ratios from ice cores  

NASA Astrophysics Data System (ADS)

This work presents a new, field-deployable technique for continuous, high-resolution measurements of methane mixing ratios from ice cores. The technique is based on a continuous flow analysis system, where ice core samples cut along the long axis of an ice core are melted continuously. The past atmospheric air contained in the ice is separated from the melt water stream via a system for continuous gas extraction. The extracted gas is dehumidified and then analyzed by a Wavelength Scanned-Cavity Ring Down Spectrometer for methane mixing ratios. We assess the performance of the new measurement technique in terms of precision (±0.8 ppbv, 1 ?), accuracy (±8 ppbv), temporal (ca. 100 s) and spatial resolution (ca. 6 cm). Using a firn air transport model, we compare the resolution of the measurement technique to the resolution of the atmospheric methane signal as preserved in ice cores in Greenland. We conclude that our measurement technique can resolve all climatically relevant variations as preserved in the ice down to an ice depth of at least 1980 m (66 000 yr before present) in the North Greenland Eemian Ice Drilling ice core. Furthermore, we describe the modifications which are necessary to make a commercially available spectrometer suitable for continuous methane mixing ratio measurements from ice cores.

Stowasser, C.; Buizert, C.; Gkinis, V.; Chappellaz, J.; Schüpbach, S.; Bigler, M.; Faïn, X.; Sperlich, P.; Baumgartner, M.; Schilt, A.; Blunier, T.

2012-01-01

427

Continuous measurements of methane mixing ratios from ice cores  

NASA Astrophysics Data System (ADS)

This work presents a new, field-deployable technique for continuous, high-resolution measurements of methane mixing ratios from ice cores. The technique is based on a continuous flow analysis system, where ice core samples cut along the long axis of an ice core are melted continuously. The past atmospheric air contained in the ice is separated from the melt water stream via a system for continuous gas extraction. The extracted gas is dehumidified and then analyzed by a Wavelength Scanned-Cavity Ring Down Spectrometer for methane mixing ratios. We assess the performance of the new measurement technique in terms of precision (±0.8 ppbv, 1?), accuracy (±8 ppbv), temporal (ca. 100 s), and spatial resolution (ca. 5 cm). Using a firn air transport model, we compare the resolution of the measurement technique to the resolution of the atmospheric methane signal as preserved in ice cores in Greenland. We conclude that our measurement technique can resolve all climatically relevant variations as preserved in the ice down to an ice depth of at least 1980 m (66 000 yr before present) in the North Greenland Eemian Ice Drilling ice core. Furthermore, we describe the modifications, which are necessary to make a commercially available spectrometer suitable for continuous methane mixing ratio measurements from ice cores.

Stowasser, C.; Buizert, C.; Gkinis, V.; Chappellaz, J.; Schüpbach, S.; Bigler, M.; Faïn, X.; Sperlich, P.; Baumgartner, M.; Schilt, A.; Blunier, T.

2012-05-01

428

Density-ratio robustness in dynamic state estimation  

NASA Astrophysics Data System (ADS)

The filtering problem is addressed by taking into account imprecision in the knowledge about the probabilistic relationships involved. Imprecision is modelled in this paper by a particular closed convex set of probabilities that is known with the name of density ratio class or constant odds-ratio (COR) model. The contributions of this paper are the following. First, we shall define an optimality criterion based on the squared-loss function for the estimates derived from a general closed convex set of distributions. Second, after revising the properties of the density ratio class in the context of parametric estimation, we shall extend these properties to state estimation accounting for system dynamics. Furthermore, for the case in which the nominal density of the COR model is a multivariate Gaussian, we shall derive closed-form solutions for the set of optimal estimates and for the credible region. Third, we discuss how to perform Monte Carlo integrations to compute lower and upper expectations from a COR set of densities. Then we shall derive a procedure that, employing Monte Carlo sampling techniques, allows us to propagate in time both the lower and upper state expectation functionals and, thus, to derive an efficient solution of the filtering problem. Finally, we empirically compare the proposed estimator with the Kalman filter. This shows that our solution is more robust to the presence of modelling errors in the system and that, hence, appears to be a more realistic approach than the Kalman filter in such a case.

Benavoli, Alessio; Zaffalon, Marco

2013-05-01

429

Discriminability of fixed-ratio schedules for pigeons: effects of absolute ratio size1  

PubMed Central

In a discrete-trial choice situation, 12 pigeons were trained to discriminate which of two different fixed ratios they had completed. Psychometric functions were obtained at three ratio requirements (i.e., with the larger ratio set at 10, 20, or 30 responses) by gradually reducing the size of the smaller value. Although different response biases developed across subjects, in each case accuracy decreased systematically with ratio difference regardless of absolute ratio requirements. Above-chance performances were maintained even at relative ratio differences of 10% or less. Estimates of the Weber fraction showed that, in general, discriminability improved with absolute ratio size up to 30 responses, and beyond, when the results of other studies are considered. A similar trend held for rats studied by other investigators in fixed-ratio “counting” tasks at lower requirements. In terms of a signal-detection analysis, performance was similar to that reported for other species and dimensions. Taken together, the results suggest that for this somewhat novel dimension the same psychophysical relations hold as are commonly observed for exteroceptive stimuli.

Hobson, Sally L.

1975-01-01

430

OFFSPRING SEX RATIO IN DEER MALE REPRODUCTIVE PHYSIOLOGY AND OFFSPRING SEX RATIO IN ODOCOILEUS VIRGINIANUS.  

Technology Transfer Automated Retrieval System (TEKTRAN)

The primary sex ratio of the family Cervidae may vary at conception and/or birth from an expected 50:50 (males:females). Fertilization by X- or Y- chromosome-bearing sperm (referred to simply as X- and Y- sperm) ultimately controls the sex of offspring; however, alteration of the fetal sex ratio co...

431

CHARACTERIZING TRITIUM WASTE USING HELIUM RATIOS  

SciTech Connect

When routine sampling revealed greatly elevated tritium levels (3.14 x 105 Bq/L [8.5-million pCi/liter]) in the groundwater near a solid waste landfill at the Hanford Site, an innovative technique was used to assess the extent of the plume. Helium-3/helium-4 ratios, relative to ambient air-in-soil gas samples, were used to identify the tritium source and initially delineate the extent of the groundwater tritium plume. This approach is a modification of a technique developed in the late 1960s to age-date deep ocean water as part of the GEOSECS ocean monitoring program. Poreda, et al. (1) and Schlosser, et al. (2) applied this modified technique to shallow aquifers. A study was also conducted to demonstrate the concept of using helium-3 as a tool to locate vadose zone sources of tritium and tracking groundwater tritium plumes at Hanford (3). Seventy sampling points were installed around the perimeter and along four transects downgradient of the burial ground. Soil gas samples were collected, analyzed for helium isotopes, and helium-3/helium-4 ratios were calculated for these 70 points. The helium ratios indicated a vadose zone source of tritium along the northern edge of the burial ground that is likely the source of tritium in the groundwater. The helium ratios also indicate the groundwater plume is traveling east-northeast from the burial ground and that no up-gradient tritium sources are affecting the burial ground. Based on the helium ratio results, six downgradient groundwater sampling locations were identified to verify the tritium plume extent and groundwater tritium concentrations. The tritium results from the initial groundwater samples confirmed that elevat