These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Spectral induced polarization porosimetry  

NASA Astrophysics Data System (ADS)

Induced polarization is a geophysical method looking to image and interpret low-frequency polarization mechanisms occurring in porous media. Below 10 kHz, the quadrature conductivity of metal-free sandy and clayey materials exhibits a distribution of relaxation times, which can be related to the pore size distribution of these porous materials. When the polarization spectra are fitted with a Cole-Cole model, we first observe that the main relaxation time is controlled by the main pore size of the material and that the Cole-Cole exponent c is never much above 0.5, a value corresponding to a Warburg function. The complex conductivity is then obtained through a convolution product between the pore size distribution and such Warburg function. We also provide a way to recover the pore size distribution by performing a deconvolution of measured spectra using the Warburg function. A new dataset of mercury porosimetry and induced polarization data of six siliciclastic materials supports the hypothesis that the Cole-Cole relaxation time is strongly controlled by the pore size, and especially the characteristic pore size corresponding to the peak of the pore size distribution from mercury porosimetry. The distribution of the pore throat sizes of these materials seems fairly well recovered using the Warburg decomposition of the spectral induced polarization spectra but additional data will be needed to confirm this finding.

Revil, A.; Florsch, N.; Camerlynck, C.

2014-08-01

2

Spectral induced polarization and electrodic potential monitoring of microbially mediated iron sulfide transformations  

E-print Network

Spectral induced polarization and electrodic potential monitoring of microbially mediated iron vulgaris. Two geoelectrical methods, (1) spectral induced polarization (SIP), and (2) electrodic potential. Ntarlagiannis, L. Slater, N. Yee, M. O'Brien, and S. Hubbard (2008), Spectral induced polarization

Hubbard, Susan

3

Pore-scale spectral induced polarization signatures associated with FeS biomineral transformations  

E-print Network

Pore-scale spectral induced polarization signatures associated with FeS biomineral transformations induced polarization (SIP) signatures in sand columns during (1) FeS biomineralization produced by sulfate), Pore-scale spectral induced polarization signatures associated with FeS biomineral transformations

Hubbard, Susan

4

Induced Polarization with Electromagnetic Coupling: 3D Spectral Imaging Theory: EMSP Project No. 73836.  

National Technical Information Service (NTIS)

This project was designed as a broad foundational study of spectral induced polarization (SIP) for characterization of contaminated sites. It encompassed laboratory studies of the effects of chemistry on induced polarization, development of 3D forward mod...

F. D. Morgan

2004-01-01

5

Spectral induced polarization signatures of abiotic FeS precipitation  

SciTech Connect

In recent years, geophysical methods have been shown to be sensitive to microbial induced mineralization processes. The spectral induced polarization (SIP) method appears to be very promising for monitoring mineralization and microbial processes. With this work, we study the links of mineralization and SIP signals, in the absence of microbial activity. We recorded the SIP response during abiotic FeS precipitation. We show that the SIP signals are diagnostic of FeS mineralization and can be differentiated from SIP signals from bio-mineralization processes. More specifically the imaginary conductivity shows almost linear dependence on the amount of FeS precipitating out of solution, above the threshold value 0.006 gr under our experimental conditions. This research has direct implications for the use of the SIP method as a monitoring, and decision making, tool for sustainable remediation of metals in contaminated soils and groundwater.

Ntarlagiannis, D.; Doherty, R.; Williams, K. H.

2010-01-15

6

Spectral induced polarization signatures of hydroxyl adsorption in porous media  

NASA Astrophysics Data System (ADS)

There is a growing interest in applying geophysical methods to monitor microbial enhanced mineral precipitation through urea hydrolysis. Sensing changes in mineral surface properties as well as changes in fluid chemistry could be used to track geochemical reactions fronts in subsurface environments. Frequency-dependent complex conductivity measured with the spectral induced polarization (SIP) technique is sensitive to both fluid chemistry and mineral surface properties. We had previously observed phase shifts (?) between current and voltage waveforms associated with hydroxyl concentration changes in a silica gel column during a urea hydrolysis experiment. In a study using less complex conditions we applied both SIP and geochemical measurements on a saturated column composed of sequential zones with Ottawa sand and silica gel in order to: 1) understand whether adsorption of hydroxyl contributes to the changes in complex conductivity, and 2) to determine whether changes in solution chemistry follow changes in surface chemistry in porous media (or vice versa). Silica gel is a highly porous form of silica (surface area is ~500 m2/g vs. <0.1 m2/g for Ottawa sand) and has a high sorption capacity for hydroxide ions. A column (48 cm) was packed with Ottawa sand at both the bottom and top sections, and with silica gel beads in the middle part of the column. The experiment started with a pH 7 sodium chloride solution (50 mM) flowing through the column at 10 ml/min, then sodium chloride solutions at higher pH (pH 8 and pH 10) replaced this solution and continued flow at the same rate for 49 hours. SIP measurements were made along the column as a function of time, and effluent samples along the column were taken for pH and conductivity measurements. The results show phase angle shifts (~4.5 mrad) in the silica gel, while no significant phase changes occurred in the Ottawa sands. Although changes in complex conductivity were only observed on synthetic high surface area material, the experiment opens the door to further investigate the correlation between complex conductivity and surface chemistry.

Zhang, C.; Johnson, T. C.; Slater, L. D.; Redden, G. D.

2010-12-01

7

Relationship between spectral induced polarization and hydraulic properties of saturated and unsaturated sandstone  

Microsoft Academic Search

There is growing interest in the use of geophysical methods for hydrological model parameterization. Empirical induced polarization (IP)-hydraulic conductivity (K) relationships have been developed, but these are only applicable to sediments in which the IP response shows limited variation with electrical current frequency. Here we examine the spectral IP response of samples taken from a UK sandstone aquifer and compare

Andrew Binley; Lee D. Slater; Melanie Fukes; Giorgio Cassiani

2005-01-01

8

A Web Interface for Software of Stochastic Inversion of Spectral Induced Polarization Data  

Microsoft Academic Search

The induced-polarization (IP) method has been used increasingly in environmental investigations because IP measurements are very sensitive to the low frequency capacitive properties of rocks and soils. The Cole-Cole model has been very useful for interpreting spectral IP data in terms of parameters, such as chargeability and time constant, which are used to estimate various subsurface properties. However, conventional methods

J. Chen; S. Pullman; S. S. Hubbard; J. Peterson

2009-01-01

9

Pore-scale spectral induced polarization (SIP) signaturesassociated with FeS biomineral transformations  

SciTech Connect

The authors measured Spectral Induced Polarization (SIP) signatures in sand columns during (1) FeS biomineralization produced by sulfate reducing bacteria (D. vulgaris) under anaerboci conditions, and (2) subsequent biomineral dissolution upon return to an aerobic state. The low-frequency (0.1-10 Hz peak) relaxations produced during biomineralization can be modeled with a Cole-Cole formulation, from which the evolution of the polarization magnitude and relaxation length scale can be estimated. They find that the modeled time constant is consistent with the polarizable elements being biomineral encrused pores. Evolution of the model parameters is consistent with FeS surface area increases and pore-size reduction during biomineral growth, and subsequent biomineral dissolution (FeS surface area decreases and pore expansion) upon return to the aerobic state. They conclude that SIP signatures are diagnostic of pore-scale geometrical changes associated with FeS biomineralization by sulfate reducing bacteria.

Slater, Lee; Ntarlagiannis, Dimitrios; Personna, Yves R.; Hubbard, Susan

2007-10-01

10

Spectral induced polarization signatures of hydroxide adsorption and mineral precipitation in porous media  

SciTech Connect

The spectral induced polarization (SIP) technique is a promising approach for delineating subsurface physical and chemical property changes in a minimally invasive manner. We investigated spatiotemporal variations in complex conductivity during evolution of urea hydrolysis and calcite precipitation reaction fronts within a silica gel column. The real and imaginary parts of complex conductivity were shown to be sensitive to changes in both solution chemistry and calcium carbonate precipitation. Distinct changes in imaginary conductivity coincided with increased hydroxide ion concentration during urea hydrolysis. In a separate experiment focused on the effect of hydroxide concentration on interfacial polarization of silica gel and well-sorted sand, we found a strong dependence of the polarization response on pH changes of the solution. We propose a conceptual model describing hydroxide ion adsorption behavior in silica gel and its control on interfacial polarizability. Our results demonstrate the utility of SIP for non-invasive monitoring of reaction fronts, and indicate its potential for quantifying geochemical processes that control the polarization responses of porous media at larger spatial scales in the natural environment.

Chi Zhang; Lee Slater; George Redden; Yoshiko Fujita; Timothy Johnson; Don Fox

2012-04-01

11

Spectral Induced Polarization Signatures of Hydroxide Adsorption and Mineral Precipitation in Porous Media  

SciTech Connect

The spectral induced polarization (SIP) technique is a promising approach for delineating subsurface physical and chemical property changes in a minimally invasive manner. To facilitate the understanding of position and chemical properties of reaction fronts that involve mineral precipitation in porous media, we investigated spatiotemporal variations in complex conductivity during evolution of urea hydrolysis and calcite precipitation reaction fronts within a silica gel column. The real and imaginary parts of complex conductivity were shown to be sensitive to changes in both solution chemistry and calcium carbonate precipitation. Distinct changes in imaginary conductivity coincided with increased hydroxide ion concentration during urea hydrolysis. In a separate experiment focused on the effect of hydroxide concentration on interfacial polarization of silica gel and well-sorted sand, we found a significant dependence of the polarization response on pH changes of the solution. We propose a conceptual model describing hydroxide ion adsorption behavior in silica gel and its control on interfacial polarizability. Our results demonstrate the utility of SIP for noninvasive monitoring of reaction fronts, and indicate its potential for quantifying geochemical processes that control the polarization responses of porous media at larger spatial scales in the natural environment.

Zhang, Chi; Slater, Lee; Redden, George D.; Fujita, Yoshiko; Johnson, Timothy C.; Fox, Don

2012-04-17

12

Spectral induced polarization signatures of hydroxide adsorption and mineral precipitation in porous media.  

PubMed

The spectral induced polarization (SIP) technique is a promising approach for delineating subsurface physical and chemical property changes in a minimally invasive manner. To facilitate the understanding of position and chemical properties of reaction fronts that involve mineral precipitation in porous media, we investigated spatiotemporal variations in complex conductivity during evolution of urea hydrolysis and calcite precipitation reaction fronts within a silica gel column. The real and imaginary parts of complex conductivity were shown to be sensitive to changes in both solution chemistry and calcium carbonate precipitation. Distinct changes in imaginary conductivity coincided with increased hydroxide ion concentration during urea hydrolysis. In a separate experiment focused on the effect of hydroxide concentration on interfacial polarization of silica gel and well-sorted sand, we found a significant dependence of the polarization response on pH changes of the solution. We propose a conceptual model describing hydroxide ion adsorption behavior in silica gel and its control on interfacial polarizability. Our results demonstrate the utility of SIP for noninvasive monitoring of reaction fronts, and indicate its potential for quantifying geochemical processes that control the polarization responses of porous media at larger spatial scales in the natural environment. PMID:22420512

Zhang, Chi; Slater, Lee; Redden, George; Fujita, Yoshiko; Johnson, Timothy; Fox, Don

2012-04-17

13

Spectral induced polarization and electrodic potential monitoring of microbially mediated iron sulfide transformations  

SciTech Connect

Stimulated sulfate-reduction is a bioremediation technique utilized for the sequestration of heavy metals in the subsurface.We performed laboratory column experiments to investigate the geoelectrical response of iron sulfide transformations by Desulfo vibriovulgaris. Two geoelectrical methods, (1) spectral induced polarization (SIP), and (2) electrodic potential measurements, were investigated. Aqueous geochemistry (sulfate, lactate, sulfide, and acetate), observations of precipitates (identified from electron microscopy as iron sulfide), and electrodic potentials on bisulfide ion (HS) sensitive silver-silver chloride (Ag-AgCl) electrodes (630 mV) were diagnostic of induced transitions between an aerobic iron sulfide forming conditions and aerobic conditions promoting iron sulfide dissolution. The SIP data showed 10m rad anomalies during iron sulfide mineralization accompanying microbial activity under an anaerobic transition. These anomalies disappeared during iron sulfide dissolution under the subsequent aerobic transition. SIP model parameters based on a Cole-Cole relaxation model of the polarization at the mineral-fluid interface were converted to (1) estimated biomineral surface area to pore volume (Sp), and (2) an equivalent polarizable sphere diameter (d) controlling the relaxation time. The temporal variation in these model parameters is consistent with filling and emptying of pores by iron sulfide biofilms, as the system transitions between anaerobic (pore filling) and aerobic (pore emptying) conditions. The results suggest that combined SIP and electrodic potential measurements might be used to monitor spatiotemporal variability in microbial iron sulfide transformations in the field.

Hubbard, Susan; Personna, Y.R.; Ntarlagiannis, D.; Slater, L.; Yee, N.; O'Brien, M.; Hubbard, S.

2008-02-15

14

Delineation of subsurface hydrocarbon contamination at a former hydrogenation plant using spectral induced polarization imaging.  

PubMed

Broadband spectral induced polarization (SIP) measurements were conducted at a former hydrogenation plant in Zeitz (NE Germany) to investigate the potential of SIP imaging to delineate areas with different BTEX (benzene, toluene, ethylbenzene, and xylene) concentrations. Conductivity images reveal a poor correlation with the distribution of contaminants; whereas phase images exhibit two main anomalies: low phase shift values (<5 mrad) for locations with high BTEX concentrations, including the occurrence of free-phase product (BTEX concentrations >1.7 g/l), and higher phase values for lower BTEX concentrations. Moreover, the spectral response of the areas with high BTEX concentration and free-phase products reveals a flattened spectrum in the low frequencies (<40 Hz), while areas with lower BTEX concentrations exhibit a response characterized by a frequency peak. The SIP response was modelled using a Debye decomposition to compute images of the median relaxation-time. Consistent with laboratory studies, we observed an increase in the relaxation-time associated with an increase in BTEX concentrations. Measurements were also collected in the time domain (TDIP), revealing imaging results consistent with those obtained for frequency domain (SIP) measurements. Results presented here demonstrate the potential of the SIP imaging method to discriminate source and plume of dissolved contaminants at BTEX contaminated sites. PMID:22784635

Flores Orozco, Adrián; Kemna, Andreas; Oberdörster, Christoph; Zschornack, Ludwig; Leven, Carsten; Dietrich, Peter; Weiss, Holger

2012-08-01

15

Delineation of subsurface hydrocarbon contamination at a former hydrogenation plant using spectral induced polarization imaging  

NASA Astrophysics Data System (ADS)

Broadband spectral induced polarization (SIP) measurements were conducted at a former hydrogenation plant in Zeitz (NE Germany) to investigate the potential of SIP imaging to delineate areas with different BTEX (benzene, toluene, ethylbenzene, and xylene) concentrations. Conductivity images reveal a poor correlation with the distribution of contaminants; whereas phase images exhibit two main anomalies: low phase shift values (< 5 mrad) for locations with high BTEX concentrations, including the occurrence of free-phase product (BTEX concentrations > 1.7 g/l), and higher phase values for lower BTEX concentrations. Moreover, the spectral response of the areas with high BTEX concentration and free-phase products reveals a flattened spectrum in the low frequencies (< 40 Hz), while areas with lower BTEX concentrations exhibit a response characterized by a frequency peak. The SIP response was modelled using a Debye decomposition to compute images of the median relaxation-time. Consistent with laboratory studies, we observed an increase in the relaxation-time associated with an increase in BTEX concentrations. Measurements were also collected in the time domain (TDIP), revealing imaging results consistent with those obtained for frequency domain (SIP) measurements. Results presented here demonstrate the potential of the SIP imaging method to discriminate source and plume of dissolved contaminants at BTEX contaminated sites.

Flores Orozco, Adrián; Kemna, Andreas; Oberdörster, Christoph; Zschornack, Ludwig; Leven, Carsten; Dietrich, Peter; Weiss, Holger

2012-08-01

16

Delineation of subsurface hydrocarbon contamination at a former hydrogenation plant using spectral induced polarization imaging  

NASA Astrophysics Data System (ADS)

In the framework of the EU FP7 project ModelPROBE, broadband spectral induced polarization (SIP) measurements were conducted at a former hydrogenation plant in Zeitz for the characterization of a hydrocarbon contaminant plume. In the source area total concentrations of BTEX contaminants partly exceed 1.5 g/l. Previous studies at the laboratory scale have demonstrated the sensitivity of SIP measurements to different concentrations of organic minerals; however, only few studies have been conducted at the field scale. The aim of this study was to investigate the potential of SIP imaging to delineate areas with different BTEX concentrations. SIP measurements were performed in the frequency range from 60 mHz to 1 kHz along a 120 m profile across the area of the former hydrogenation plant. At a later stage, a trench was excavated along the location of the profile in order to remove pipes, foundations and different sources of anthropogenic noise associated with the hydrogenation plant. Thereafter, SIP measurements were repeated inside the trench to study the effect of anthropogenic noise on the SIP images. Computed images for the data collected before and after the excavation of the trench show similar results validating the proposed approach even in the presence of anthropogenic noise. SIP images, for frequencies below 100 Hz, exhibit two main anomalies: low phase shift values (~ 5 mrad) for locations with free phase product (BTEX concentrations > 1.7 g/l); whereas relatively high polarization values (> 10 mrad) were observed for lower BTEX concentrations (1 - 1.7 g/l). Moreover, the spectral response of the areas where free phase product was detected reveals a flattened spectrum; while the areas with lower concentrations exhibit a typical Cole-Cole response. Based on these results, SIP imaging appears to be a suitable tool to delineate source-zones at highly contaminated sites.

Flores Orozco, A.; Kemna, A.; Oberdoerster, C.; Zschornack, L.; Leven, C.; Dietrich, P.; Weiss, H.

2011-12-01

17

Spectral induced polarization response to nanoparticles in a saturated sand matrix  

NASA Astrophysics Data System (ADS)

Nanoparticles have grown in importance over the last decade with significant consumer and industrial applications. Yet, the behavior (fate and transport) of nanoparticles in the environment is virtually unknown. Research is needed to identify, characterize, and monitor nanomaterials in the subsurface. Here, we investigate the spectral induced polarization (SIP) response of nanometallic powders (nZVI, nAg, nTiO 2, nZnO, and nCeO 2) in porous geologic media. Our main objective is to determine the sensitivity of the SIP response (0.1-10,000 Hz) to the presence of nanoparticles (metals and metal oxides) in porous media. The SIP response was tested under various conditions: increasing particle concentration under constant solution chemistry; varying solution molarity (0.0 M-1.0 M), and varying solution valence (+ 1, + 2, + 3 valence) under constant particle volume. We examine the results in terms of phase shift and resistance magnitude. Our data suggest that the oxide nanoparticles do not show SIP responses to increasing particle concentration, solution valence, and molarity, while the metallic particles show a clear response to increasing particle concentration, and frequency. Silver was the only material to show any significant response to increasing solution molarity, valence, and frequency. Because of the high propensity of the nanoparticles to form aggregates, they essentially behave as colloidal and clay particles allowing us to apply conventional SIP theory to our interpretation. We suggest that the oxidation state of the metals diminishes their SIP response consistent with more recent studies that have documented that polarization decreases with oxidation of metallic particles. We infer from our results that nanoparticle crystalline composition and aggregation effects control the SIP response of nanoparticles in porous media.

Joyce, Ryan A.; Glaser, Danney R.; Werkema, D. Dale; Atekwana, Estella A.

2012-02-01

18

Mapping oil-contaminated sand and till with the spectral induced polarization (SIP) method  

SciTech Connect

The laboratory and field results from an environmental application of the spectral induced polarization (SIP) method are presented. The phase spectra of the resistivity of uncontaminated glacial till, silt, sand and gravel were measured in the laboratory. The effects of waste oil and motor oil on the phase and amplitude spectra of the resistivity were studied using artificially contaminated sand and till samples and mineral soil samples from real waste sites. Field IP and SIP measurements were also made at the waste sites. The laboratory phase spectra of sands and tills were straight or slightly concave upwards in a log-log plot. The phase angle varies between 0.1 and 20 mrad at 1 Hz frequency and increases towards higher frequencies with a slope of 0.15--0.25. In laboratory tests, motor oil and waste oil changed the phase and amplitude spectra of sand and till. At first, the amplitude and phase decreased due to oil contamination. Later, during continued maturation, both the amplitude and phase increased. After a few days or weeks of maturation, some of the contaminated samples showed a convex-upwards phase spectrum. The features observed in artificially contaminated samples were also detected in the sample material from real waste sites. Furthermore, the in situ results from the waste sites were in agreement with the laboratory results. In laboratory tests, the phase spectra of clean sand and till remained stable with time, whereas the phase spectra of oil-contaminated samples changed with increasing maturation time. This, together with the field results, suggests that differences between the spectra of clean and polluted soils, and also changes occurring in the phase spectra of contaminated soils with time, can be indicative of contamination.

Vanhala, H. [Geological Survey of Finland, Espoo (Finland)] [Geological Survey of Finland, Espoo (Finland)

1997-03-01

19

Spectral Induced Polarization (SIP) monitoring during Microbial Enhanced Oil Recovery (MEOR)  

NASA Astrophysics Data System (ADS)

Jeffrey Heenan, Dimitrios Ntarlagiannis, Lee Slater Department of Earth and Environmental Sciences, Rutgers University, Newark NJ Microbial Enhanced Oil Recovery (MEOR) is an established, cost effective, method for enhancing tertiary oil recovery. Although not commonly used for shallow heavy oils, it could be a viable alternative since it can offer sustainable economic recovery and minimal environmental impact. A critical component of successful MEOR treatments is accurate, real time monitoring of the biodegradation processes resulting from the injection of microbial communities into the formation; results of recent biogeophysical research suggest that minimally-invasive geophysical methods could significantly contribute to such monitoring efforts. Here we present results of laboratory experiments, to assess the sensitivity of the spectral induced polarization method (SIP) to MEOR treatments. We used heavy oil, obtained from a shallow oilfield in SW Missouri, to saturate three sand columns. We then followed common industry procedures,and used a commercially available microbial consortia, to treat the oil columns. The active MEOR experiments were performed in duplicate while a control column maintained similar conditions, without promoting microbial activity and oil degradation. We monitored the SIP signatures, between 0.001 Hz and 1000 Hz, for a period of six months. To support the geophysical measurements we also monitored common geochemical parameters, including pH, Eh and fluid conductivity, and collected weekly fluid samples from the outflow and inflow for further analysis; fluid samples were analyzed to confirm that microbes actively degraded the heavy oils in the column while destructive analysis of the solid materials was performed upon termination of the experiment. Preliminary analysis of the results suggests that SIP is sensitive to MEOR processes. In both inoculated columns we recorded an increase in the low frequency polarization with time; measureable changes up to 3.5 mrads in the phase shift were recorded for both active columns, and for all electrode pairs. On the contrary, no change was observed in the control column for the duration of the experiment. These results may indicate that remote geophysical methods could successfully complement current MEOR monitoring schemes for promoting sustainable oil recovery.

Heenan, J. W.; Ntarlagiannis, D.; Slater, L. D.

2010-12-01

20

Monitoring of CO2-induced geochemical changes in a shallow aquifer by time domain spectral induced polarization  

NASA Astrophysics Data System (ADS)

Contamination of potable groundwater by leaking CO2 is a potential risk of carbon sequestration. With the help of a field experiment, we investigate if surface monitoring of electrical resistivity and induced polarization can detect geochemical changes induced by CO2 in a shallow aquifer. For this purpose, we injected CO2 at a depth of 5 and 10 m and monitored its migration using 320 electrodes on a 126 m × 25 m surface grid. A fully automated acquisition system continuously collected direct current (DC) resistivity and full-decay induced polarization (IP) data and uploaded it into an online database. CO2 was injected for a period of 72 days and DC/IP monitoring started 20 days before and continued until 120 days after the beginning of the injection. The DC/IP data were supplemented by chemical analysis of water samples collected in 29 wells at time intervals of approximately 10 days. DC/IP data are inverted using a 2-D algorithm (AarhusInv) that incorporates the full voltage decay of the IP response to resolve DC resistivity, intrinsic chargeability and spectral IP content parameterized using the Cole-Cole model. Borehole information and a baseline inversion reveals the geology at the site consisting of aeolian sands near the surface, glacial sands between 5 and 10 m depth and marine sands below 10 m depth. Following the injection, we use a time-lapse inversion where differences in the DC/IP data are inverted for changes to the Cole-Cole parameters. Two different geochemical signatures that occur due to the injected CO2 are evident both in the geophysical inversions and the water samples. The first and clearest subsurface signal is a decrease in DC resistivity that moves advectively with the groundwater. The area of resistivity decrease expands with time in the direction of the groundwater flow and there is good correlation between geophysical and geochemical results. A chargeability decrease after the injection has been also observed, but in contrast to the decrease in DC resistivity, the chargeability anomaly remains localized around and slightly downstream of the injection wells throughout the experiment. This chargeability decrease correlates in space and time with a decrease in pH, which is observed in the water samples. Consequently, we attribute this change in chargeability to pH-induced changes to the grains surfaces. These results highlight the potential for monitoring of field scale geochemical changes by means of surface DC/IP measurements. Especially the different development of the DC resistivity and chargeability anomalies and the different associated geochemical processes, highlight the added value of induced polarization to resistivity monitoring.

Doetsch, Joseph; Fiandaca, Gianluca; Auken, Esben; Christiansen, Anders V.; Cahill, Aaron G.; Jakobsen, Rasmus

2014-05-01

21

Laboratory technique for measurement of spectral induced polarization response of soil sampies1  

Microsoft Academic Search

Laboratory measurements of soil samples are necessary to assess the effect of mineralogy, grain size distribution, moisture content, and electrolyte composition the resistivity spectrum of soil material. Laboratory results are also required for the interpretation of field data. Induced polarization phenomena in glacial soils are poorly understood and so far no convenient laboratory techniques are available for measurement. Coarse grain

Heikki Vanhala; Heikki Soininen

1995-01-01

22

Pollutant monitoring in a sand-column with Spectral Induced Polarization, Time Domain Reflectometry, and geochemistry analysis: experimentation and modeling  

NASA Astrophysics Data System (ADS)

Geoelectrical methods have been proposed as non-invasive techniques to monitor the soil contamination. It is now well known that electrical properties of porous media depend on the composition of the electrolyte and its interaction with the surface of the minerals. So, understanding in the laboratory the influence of change in electrolyte composition on geolectrical measurements is critical to validate behaviour models. Following this path, we have been using two geolectrical methods, Time Domain Reflectometry and Spectral Induced Polarization measurements. We carried out column experiments to investigate the effect of mineralogy and electrolyte composition on the electrical signatures resulting from pollutant migration (CuSO4 and ZnSO4) in saturated flow conditions, and adsorption/desorption reaction between Cu, Zn and the surface of the minerals. Laboratory columns are filled with a 100 µm well sorted sand (nearly pure silica). These columns are saturated with different well known electrolytes (composition of the electrolyte is progressively modified during the course of the experiment). The evolution of the chemical composition in columns has been monitored to have a well understanding of transport and reaction processes. Spectral Induced Polarization measurements were performed in the frequency range 45 mHz - 12 kHz. Low-frequencies polarization characteristics in a such environment depend on two processes. There is the polarization of the mineral/electrolyte interface coating the surface of the grains (polarization of the Stern layer) and the Maxwell-Wagner polarization associated with accumulation of the electrical charges in the pore space of the medium. The model of low-frequency conductivity is connected to a double-layer model of electrochemical processes occurring at the surface of silica. Characteristics of this double-layer model (i.e., distribution of counterions between the diffuse layer and Stern layer) are computed with the code Phreeqc (USGS). Experimentation and modeling allows us to connect characteristics of the electrolyte and geoelectric responses.

Pierre, V.; Schmutz, M.; Franceschi, M.; Revil, A.

2009-12-01

23

A new model for the spectral induced polarization signature of bacterial growth in porous media  

NASA Astrophysics Data System (ADS)

Recent biogeophysics studies demonstrated the sensitivity of complex conductivity to bacterial growth and microbial mediated mineral transformations in porous media. Frequency-domain induced polarization is a minimally invasive manner to measure the complex conductivity of a material over a broad range of frequencies. The real component of complex conductivity is associated with electromigration of the charge carriers, and the imaginary component represents reversible energy storage of charge carriers at polarization length scales. Quantitative relationship between frequency-domain induced polarization responses and bacterial growth and decay in porous media is analyzed in this study using a new developed model. We focus on the direct contribution of bacteria themselves to the complex conductivity in porous media in the absence of biomineralization. At low frequencies, the induced polarization of bacteria (?-polarization) is related to the properties of the electrical double layer surrounding the membrane surface of bacteria. Surface conductivity and ?-polarization are due to the Stern layer of the counterions occurring in a brush of polymers coating the surface of the bacteria, and can be related to the cation exchange capacity of the bacteria. From the modeling results, at low frequencies (< 10 Hz), the mobility of the counterions (K+) in the Stern layer of bacteria is found to be extremely small (4.7×10-10 m2s-1 V-1 at 25°C), and is close to the mobility of the same counterions along the surface of clay minerals (Na+, 1.5×10-10 m2s-1 V-1 at 25°C). This result is in agreement with experimental observations and it indicates a very low relaxation frequency for the ?-polarization of the bacteria cells (typically around 0.1 to 5 Hertz). By coupling this new model with reactive transport modeling in which the evolution of bacterial populations are usually described by Monod kinetics, we show that the changes in imaginary conductivity with time can be used to determine bacterial growth kinetics parameters such as the growth and endogenous decay coefficient.

Zhang, C.; Revil, A.; Atekwana, E. A.; Jardani, A.; Smith, S.

2012-12-01

24

Characterization of Shallow Subsurface Ice, Water, and Biosignatures on Mars Using Spectral Induced Polarization  

NASA Astrophysics Data System (ADS)

The frequency and strength of electrical polarizations gives information on the identity and abundance of certain materials, analogous to classical spectroscopy. Geophysical implementation from Mars surface is sensitive to several meters depth.

Grimm, R. E.; Stillman, D. E.

2014-07-01

25

Estimating the spatiotemporal distribution of geochemical parameters associated with biostimulation using spectral induced polarization data and hierarchical Bayesian models  

NASA Astrophysics Data System (ADS)

We developed a hierarchical Bayesian model to estimate the spatiotemporal distribution of aqueous geochemical parameters associated with in-situ bioremediation using surface spectral induced polarization (SIP) data and borehole geochemical measurements collected during a bioremediation experiment at a uranium-contaminated site near Rifle, Colorado (USA). The SIP data were first inverted for Cole-Cole parameters, including chargeability, time constant, resistivity at the DC frequency, and dependence factor, at each pixel of two-dimensional grids using a previously developed stochastic method. Correlations between the inverted Cole-Cole parameters and the wellbore-based groundwater chemistry measurements indicative of key metabolic processes within the aquifer (e.g., ferrous iron, sulfate, uranium) were established and used as a basis for petrophysical model development. The developed Bayesian model consists of three levels of statistical submodels: (1) data model, providing links between geochemical and geophysical attributes, (2) process model, describing the spatial and temporal variability of geochemical properties in the subsurface system, and (3) parameter model, describing prior distributions of various parameters and initial conditions. The unknown parameters were estimated using Markov chain Monte Carlo methods. By combining the temporally distributed geochemical data with the spatially distributed geophysical data, we obtained the spatiotemporal distribution of ferrous iron, sulfate, and sulfide, and their associated uncertainty information. The obtained results can be used to assess the efficacy of the bioremediation treatment over space and time and to constrain reactive transport models.

Chen, Jinsong; Hubbard, Susan S.; Williams, Kenneth H.; Flores Orozco, AdriáN.; Kemna, Andreas

2012-05-01

26

INJECTION ELECTRODE POLARIZATION RESISTIVITY AND INDUCED POLARIZATION  

E-print Network

INJECTION ELECTRODE POLARIZATION IN RESISTIVITY AND INDUCED POLARIZATION J.B. Merriam University.merriam@usask.ca Abstract Polarization of injection electrodes in resistivity and induced polarization may reach several will only be a problem if the received signal is very much smaller than the polarization. In induced

Merriam, James

27

A Hierarchical Bayesian Model for Estimating Remediation-induced Biogeochemical Transformations Using Spectral Induced Polarization Data: Development and Application to the Contaminated DOE Rifle (CO) Site  

NASA Astrophysics Data System (ADS)

Although in-situ bioremediation is often considered as a key approach for subsurface environmental remediation, monitoring induced biogeochemical processes, needed to evaluate the efficacy of the treatments, is challenging over field relevant scales. In this study, we develop a hierarchical Bayesian model that builds on our previous framework for estimating biogeochemical transformations using geochemical and geophysical data obtained from laboratory column experiments. The new Bayesian model treats the induced biogeochemical transformations as both spatial and temporal (rather than just temporal) processes and combines time-lapse borehole ‘point’ geochemical measurements with inverted surface- or crosshole-based spectral induced polarization (SIP) data. This model consists of three levels of statistical sub-models: (1) data model (or likelihood function), which provides links between the biogeochemical end-products and geophysical attributes, (2) process model, which describes the spatial and temporal variability of biogeochemical properties in the disturbed subsurface systems, and (3) parameter model, which describes the prior distributions of various parameters and initial conditions. The joint posterior probability distribution is explored using Markov Chain Monte Carlo sampling methods to obtain the spatial and temporal distribution of the hidden parameters. We apply the developed Bayesian model to the datasets collected from the uranium-contaminated DOE Rifle site for estimating the spatial and temporal distribution of remediation-induced end products. The datasets consist of time-lapse wellbore aqueous geochemical parameters (including Fe(II), sulfate, sulfide, acetate, uranium, chloride, and bromide concentrations) and surface SIP data collected over 13 frequencies (ranging from 0.065Hz to 256Hz). We first perform statistical analysis on the multivariate data to identify possible patterns (or ‘diagnostic signatures’) of bioremediation, and then we invert the time-lapse SIP data for chargeability and time constant using Cole-Cole models. By combining the limited borehole time series data with spatially distributed time-lapse geophysical data, we can obtain the spatial and temporal distribution of the bioremediation end-products (such as volume fraction of FeS and calcite) and their associated uncertainty information. Our study results show how time-lapse SIP datasets, when incorporated into a Bayesian hierarchical model, can be useful for quantifying the spatiotemporal distribution of remediation-induced end-products. The study also documents how the diagnostic geophysical signatures can be useful for identifying when and where critical, remediation-induced system transitions occur, such as those accompanying a rebound in aquifer redox status and the associated impact on immobilized contaminant stability.

Chen, J.; Hubbard, S. S.; Williams, K. H.; Tuglus, C.; Flores-Orozco, A.; Kemna, A.

2010-12-01

28

Injection Electrode Polarization in Induced Polarization  

E-print Network

Injection Electrode Polarization in Induced Polarization J.B. Merriam Department of Geological-966-8593, E-mail: jim.merriam@usask.ca Polarization at the boundary between the current injection electrodes and the pore fluid occurs by a number of mechanisms. The polarization can be described as a variable contact

Merriam, James

29

3-D Spectral Induced Polarization (IP) Imaging: Non-Invasive Characterization of Contaminant Plumes. Annual Progress Report for Period September 15, 1996-September 14, 1997.  

National Technical Information Service (NTIS)

The objective of this project is to develop the scientific basis for characterizing contaminant plumes in the earths subsurface using field measurements of induced polarization (IP) effects. Our first-year accomplishments are (1) laboratory experiments on...

F. D. Morgan, D. P. Lesmes, W. Rodi, W. Shi, K. M. Frye, J. Sturrock

1997-01-01

30

A comparison between Gauss-Newton and Markov chain Monte Carlo basedmethods for inverting spectral induced polarization data for Cole-Coleparameters  

SciTech Connect

We develop a Bayesian model to invert spectral induced polarization (SIP) data for Cole-Cole parameters using Markov chain Monte Carlo (MCMC) sampling methods. We compare the performance of the MCMC based stochastic method with an iterative Gauss-Newton based deterministic method for Cole-Cole parameter estimation through inversion of synthetic and laboratory SIP data. The Gauss-Newton based method can provide an optimal solution for given objective functions under constraints, but the obtained optimal solution generally depends on the choice of initial values and the estimated uncertainty information is often inaccurate or insufficient. In contrast, the MCMC based inversion method provides extensive global information on unknown parameters, such as the marginal probability distribution functions, from which we can obtain better estimates and tighter uncertainty bounds of the parameters than with the deterministic method. Additionally, the results obtained with the MCMC method are independent of the choice of initial values. Because the MCMC based method does not explicitly offer single optimal solution for given objective functions, the deterministic and stochastic methods can complement each other. For example, the stochastic method can first be used to obtain the means of the unknown parameters by starting from an arbitrary set of initial values and the deterministic method can then be initiated using the means as starting values to obtain the optimal estimates of the Cole-Cole parameters.

Chen, Jinsong; Kemna, Andreas; Hubbard, Susan S.

2008-05-15

31

Chemically induced unfolding of bovine serum albumin by urea and sodium dodecyl sulfate: a spectral study with the polarity-sensitive charge-transfer fluorescent probe (E)-3-(4-methylaminophenyl)acrylic acid methyl ester.  

PubMed

Sensitivity of the charge-transfer (CT) band of the fluorescence probe (E)-3-(4-methylaminophenyl)acrylic acid methyl ester (MAPAME) towards the polarity of its immediate environment is employed to investigate the binding interaction of the probe with bovine serum albumin (BSA) and uncoiling of BSA by the denaturants urea and sodium dodecyl sulfate micelles. Binding of the probe with BSA produces a blue shift and enhanced intensity of the CT emission band which clearly point toward a decrease in polarity of the immediate environment of MAPAME. This is expected, since binding with BSA moves the probe from a polar water environment to a much less polar, hydrophobic protein interior, where the CT band is expected to be blue-shifted. Higher intensity arises due to fewer non-radiative decay paths available to the probe in the hydrophobic protein environment. Chemically induced unfolding of BSA by urea and sodium dodecyl sulfate is tracked by monitoring the induced spectral changes of the protein-bound probe MAPAME. Red-edge excitation shift or REES, fluorescence resonance energy transfer (FRET) and anisotropy measurements are used to investigate and monitor these binding and unfolding processes. PMID:19466702

Ghosh, Shalini; Guchhait, Nikhil

2009-07-13

32

THE EFFECT OF SYSTEMATICS ON POLARIZED SPECTRAL INDICES  

SciTech Connect

We study four particularly bright polarized compact objects (Tau A, Vir A, 3C 273, and For A) in the 7 year Wilkinson Microwave Anisotropy Probe (WMAP) sky maps, with the goal of understanding potential systematics involved in the estimation of foreground spectral indices. First, we estimate the spectral index, the polarization angle, the polarization fraction, and the apparent size and shape of these objects when smoothed to a nominal resolution of 1 Degree-Sign FWHM. Second, we compute the spectral index as a function of polarization orientation, {alpha}. Because these objects are approximately point sources with constant polarization angle, this function should be constant in the absence of systematics. However, for the K and Ka band WMAP data we find strong index variations for all four sources. For Tau A, we find a spectral index of {beta} = -2.59 {+-} 0.03 for {alpha} = 30 Degree-Sign , and {beta} = -2.03 {+-} 0.01 for {alpha} = 50 Degree-Sign . On the other hand, the spectral index between the Ka and Q bands is found to be stable. A simple elliptical Gaussian toy model with parameters matching those observed in Tau A reproduces the observed signal, and shows that the spectral index is particularly sensitive to the detector polarization angle. Based on these findings, we first conclude that estimation of spectral indices with the WMAP K band polarization data at 1 Degree-Sign scales is not robust. Second, we note that these issues may be of concern for ground-based and sub-orbital experiments that use the WMAP polarization measurements of Tau A for calibration of gain and polarization angles.

Wehus, I. K. [Oxford Astrophysics, University of Oxford, DWB, Keble Road, Oxford OX1 3RH (United Kingdom)] [Oxford Astrophysics, University of Oxford, DWB, Keble Road, Oxford OX1 3RH (United Kingdom); Fuskeland, U.; Eriksen, H. K., E-mail: i.k.wehus@fys.uio.no [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, N-0315 Oslo (Norway)

2013-02-15

33

Single camera based spectral domain polarization sensitive optical coherence tomography  

Microsoft Academic Search

We developed a new spectral domain polarization sensitive optical coherence tomography (SD PS-OCT) system that requires only a single spectrometer CCD camera. The spectra of the horizontal and vertical polarization channels are imaged adjacent to each other on a 2048 pixel line scan camera, using 1024 pixels for each channel. Advantages of the system are reduced costs and complexity, lower

Bernhard Baumann; Erich Götzinger; Michael Pircher; Christoph K. Hitzenberger

2007-01-01

34

Spectral and Polarization Sensitivity of the Dipteran Visual System  

PubMed Central

Spectral and polarization sensitivity measurements were made at several levels (retina, first and third optic ganglion, cervical connective, behavior) of the dipteran visual nervous system. At all levels, it was possible to reveal contributions from the retinular cell subsystem cells 1 to 6 or the retinular cell subsystem cells 7 and 8 or both. Only retinular cells 1 to 6 were directly studied, and all possessed the same spectral sensitivity characterized by two approximately equal sensitivity peaks at 350 and 480 nm. All units of both the sustaining and on-off variety in the first optic ganglion exhibited the same spectral sensitivity as that of retinular cells 1 to 6. It was possible to demonstrate for motion detection and optomotor responses two different spectral sensitivities depending upon the spatial wavelength of the stimulus. For long spatial wavelengths, the spectral sensitivity agreed with retinular cells 1 to 6; however, the spectral sensitivity at short spatial wavelengths was characterized by a single peak at 465 nm reflecting contributions from the (7, 8) subsystem. Although the two subsystems exhibited different spectral sensitivities, the difference was small and no indication of color discrimination mechanisms was observed. Although all retinular cells 1 to 6 exhibited a preferred polarization plane, sustaining and on-off units did not. Likewise, motion detection and optomotor responses were insensitive to the polarization plane for long spatial wavelength stimuli; however, sensitivity to select polarization planes was observed for short spatial wavelengths. PMID:5027759

McCann, Gilbert D.; Arnett, David W.

1972-01-01

35

Spectral-domain measurement of beat length in polarization-maintaining fibers  

NASA Astrophysics Data System (ADS)

A spectral white-light interferometric (WLI) method for measuring the beat length in high birefringence polarization-maintaining fibers (PMFs) is presented. The approach is based on the stress-induced polarization mode coupling between the two polarization eigenmodes and utilizes their spectral interferograms. By recording the spectral interferograms before and after the displacement of the force, the beat length can be obtained by the displacement of the force and the relative phase variation retrieved from the two spectral interferograms. According to the principle that the phase difference between adjacent fringes peaks is 2?, the phase can be retrieved from the interferograms simply. The factors affecting the measurement precision of this method and the main source of errors are investigated in detail.

Chen, Xinwei; Liu, Tiegen; Zhang, Hongxia; Lu, Wei; Huang, Lichang; Cheng, Liang; Zhang, Yimo

2012-12-01

36

Spectral distortions in the cosmic microwave background polarization  

E-print Network

We compute the spectral distortions of the Cosmic Microwave Background (CMB) polarization induced by non-linear effects in the Compton interactions between CMB photons and cold intergalactic electrons. This signal is of the $y$-type and is dominated by contributions arising from the reionized era. We stress that it is not shadowed by the thermal SZ effect which has no equivalent for polarization. We decompose its angular dependence into $E$- and $B$-modes, and we calculate the corresponding power spectra, both exactly and using a suitable Limber approximation that allows a simpler numerical evaluation. We find that $B$-modes are of the same order of magnitude as $E$-modes. Both spectra are relatively flat, peaking around $\\ell=280$, and their overall amplitude is directly related to the optical depth to reionization. Moreover, we find this effect to be one order of magnitude larger than the non-linear kinetic Sunyaev-Zel'dovich effect in galaxy clusters. Finally, we discuss how to improve the detectability of our signal by cross-correlating it with other quantities sourced by the flow of intergalactic electrons.

Sebastien Renaux-Petel; Christian Fidler; Cyril Pitrou; Guido W. Pettinari

2013-12-16

37

Inversion of induced polarization data  

Microsoft Academic Search

The authors developed three methods to invert induced polarization (IP) data. The foundation for their algorithms is an assumption that the ultimate effect of chargeability is to alter the effective conductivity when current is applied. This assumption, which was first put forth by Siegel and has been routinely adopted in the literature, permits the IP responses to be numerically modeled

Douglas W. Oldenburg; Y. Li

1994-01-01

38

Is there spectral variation in the polarized reflectance of leaves?  

NASA Astrophysics Data System (ADS)

The light scattered by plant canopies depends in part on the light scattering/absorbing properties of the leaves and is key to understanding the remote sensing process in the optical domain. Here we specifically looked for evidence of fine spectral detail in the polarized portion of the light reflected from the individual leaves of five species of plants measured at Brewsters angle over the wavelength range 450 to 2300nm. Our results show no strong, unambiguous evidence of narrow band spectral variation of the polarized portion of the reflectance factor.

Vanderbilt, V. C.; Daughtry, C. S. T.; Biehl, L. L.

2014-05-01

39

Polarized nuclear target based on parahydrogen induced polarization  

SciTech Connect

We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast ({approx}100 HZ) polarization oscillation (akin to polarization reversal), and operation with large intensity of an electron beam.

D. Budker, M.P. Ledbetter, S. Appelt, L.S. Bouchard, B. Wojtsekhowski

2012-12-01

40

Polarization and spectral properties of aminoacid crystals  

NASA Astrophysics Data System (ADS)

The aim of this work is the investigation of polarization correlated structure of Muller matrix images of thin film amino acids and their absorption spectrums in IR region. The following tasks have been solved: the study of the optical properties of amino acids, the modeling of optical characteristics of biocrystals, the experimental investigation of coordinate distribution of Muller matrix images of thin film amino acids, their statistic and correlated characteristics with the use of Stocks polarimetry of their images. The samples of 22 aminoacids were used in the experiment. The research methods are Mueller matrices polarimetry and spectrometry in 2 500 - 40 000 nm.

Yermolenko, S. B.

2012-01-01

41

Spectral and Polarization Sensitivity of the Dipteran Visual System  

Microsoft Academic Search

Spectral and polarization sensitivity measurements were made at several levels (retina, first and third optic ganglion, cervical connective, be- havior) of the dipteran visual nervous system. At all levels, it was possible to reveal contributions from the retinular cell subsystem cells 1 to 6 or the retinular cell subsystem cells 7 and 8 or both. Only retinular cells I to

GILBERT D. McCANN; DAVID W. ARNETT

2009-01-01

42

Programmable polarization-independent spectral phase compensation and pulse shaping  

E-print Network

. Backus, and G. Vdovin, "Adaptive pulse compression for transform-limited 15-fs high-energy pulse Fourier transform pulse shapers [1] are an important tool for controlling the waveforms of ultrafastProgrammable polarization-independent spectral phase compensation and pulse shaping R. D. Nelson, D

Purdue University

43

Spontaneous Polarization-Induced Nanohelixes, Nanosprings, and  

E-print Network

Spontaneous Polarization-Induced Nanohelixes, Nanosprings, and Nanorings of Piezoelectric Nanobelts polarization is induced across the nanobelt thickness. As a result, right-handed helical nanostructures-surface-dominated ZnO nanobelts are likely to be an ideal system for understanding piezoelectricity and polarization-induced

Wang, Zhong L.

44

Polarized nuclear target based on parahydrogen induced polarization  

E-print Network

We discuss a novel concept of a polarized nuclear target for accelerator fixed-target scattering experiments, which is based on parahydrogen induced polarization (PHIP). One may be able to reach a 33% free-proton polarization in the ethane molecule. The potential advantages of such a target include operation at zero magnetic field, fast ($\\sim$100 Hz) polarization reversal, and operation with large intensity of an electron beam.

D. Budker; M. P. Ledbetter; S. Appelt; L. S. Bouchard; B. Wojtsekhowski

2012-03-13

45

Propagation-induced polarization changes in partially coherent optical beams  

Microsoft Academic Search

Propagation of a partially coherent optical beam inside a linear, nondispersive, dielectric medium is studied, taking into account the vector nature of the electromagnetic field. Propagation-induced polarization changes are studied by using the Gaussian-Schell model for the cross-spectral-density tensor. The degree of polar- ization changes with propagation and also becomes nonuniform across the beam cross section. The extent of these

Govind P. Agrawal; Emil Wolf

2000-01-01

46

An Integrated Imaging Detector of Polarization and Spectral Content  

NASA Technical Reports Server (NTRS)

A new type of image detector has been designed to simultaneously analyze the polarization of light at all picture elements in a scene. The Integrated Dual Imaging Detector (IDID) consists of a polarizing beamsplitter bonded to a charge-coupled device (CCD), with signal-analysis circuitry and analog-to-digital converters, all integrated on a silicon chip. It should be capable of 1:10(exp 4) polarization discrimination. The IDID should simplify the design and operation of imaging polarimeters and spectroscopic imagers used, for example, in atmospheric and solar research. Innovations in the IDID include (1) two interleaved 512 x 1024-pixel imaging arrays (one for each polarization plane); (2) large dynamic range (well depth of 10(exp 6) electrons per pixel); (3) simultaneous readout of both images at 10 million pixels per second each; (4) on-chip analog signal processing to produce polarization maps in real time; (5) on-chip 10-bit A/D conversion. When used with a lithium-niobate Fabry-Perot etalon or other color filter that can encode spectral information as polarization, the IDID can collect and analyze simultaneous images at two wavelengths. Precise photometric analysis of molecular or atomic concentrations in the atmosphere is one suggested application. When used in a solar telescope, the IDID will charge the polarization, which can then be converted to maps of the vector magnetic fields on the solar surface.

Rust, D. M.; Thompson, K. E.

1993-01-01

47

Spectral signatures of polar stratospheric clouds and sulfate aerosol  

NASA Technical Reports Server (NTRS)

Multiwavelength observations of Antarctic and midlatitude aerosol by the Cryogenic Limb Array Etalon Spectrometer (CLAES) experiment on the Upper Atmosphere Research Satellite (UARS) are used to demonstrate a technique that identifies the location of polar stratospheric clouds. The technique discussed uses the normalized area of the triangle formed by the aerosol extinctions at 925, 1257, and 1605/cm (10.8, 8.0, and 6.2 micrometers) to derive a spectral aerosol measure M of the aerosol spectrum. Mie calculations for spherical particles and T-matrix calculations for spheriodal particles are used to generate theoretical spectral extinction curves for sulfate and polar stratospheric cloud particles. The values of the spectral aerosol measure M for the sulfate and polar stratospheric cloud particles are shown to be different. Aerosol extinction data, corresponding to temperatures between 180 and 220 K at a pressure of 46 hPa (near 21-km altitude) for 18 August 1992, are used to demonstrate the technique. Thermodynamic calculations, based upon frost-point calculations and laboratory phase-equilibrium studies of nitric acid trihydrate, are used to predict the location of nitric acid trihydrate cloud particles.

Massie, S. T.; Bailey, P. L.; Gille, J. C.; Lee, E. C.; Mergenthaler, J. L.; Roche, A. E.; Kumer, J. B.; Fishbein, E. F.; Waters, J. W.; Lahoz, W. A.

1994-01-01

48

Self-induced polarization anisoplanatism  

NASA Astrophysics Data System (ADS)

This paper suggests that the astronomical science data recorded with low F# telescopes for applications requiring a known point spread function shape and those applications requiring instrument polarization calibration may be compromised unless the effects of vector wave propagation are properly modeled and compensated. Exoplanet coronagraphy requires "matched filter" masks and explicit designs for the real and imaginary parts for the mask transmittance. Three aberration sources dominate image quality in astronomical optical systems: amplitude, phase and polarization. Classical ray-trace aberration analysis used today by optical engineers is inadequate to model image formation in modern low F# highperformance astronomical telescopes. We show here that a complex (real and imaginary) vector wave model is required for high performance, large aperture, very wide-field, low F# systems. Self-induced polarization anisoplanatism (SIPA) reduces system image quality, decreases contrast and limits the ability of image processing techniques to restore images. This paper provides a unique analysis of the image formation process to identify measurements sensitive to SIPA. Both the real part and the imaginary part of the vector complex wave needs to be traced through the entire optical system, including each mirror surface, optical filter, and all masks. Only at the focal plane is the modulus squared taken to obtain an estimate of the measured intensity. This paper also discusses the concept of the polarization conjugate filter, suggested by the author to correct telescope/instrument corrupted phase and amplitude and thus mitigate6, in part the effects of phase and amplitude errors introduced by reflections of incoherent white-light from metal coatings.

Breckinridge, James B.

2013-09-01

49

Multilayer thin film design for far ultraviolet polarizers using an induced transmission and absorption technique  

NASA Technical Reports Server (NTRS)

An explanation of induced transmission for spectral regions excluding the far ultraviolet (FUV) is given to better understand how induced transmission and absorption can be used to design effective polarizers in the FUV spectral region. We achieve high s-polarization reflectance and a high degree of polarization (P equals (Rs-Rp)/(Rs+Rp)) by means of a MgF2/Al/MgF2 three layer structure on an opaque thick film of Al as the substrate. For example, our polarizer designed for the Lyman-alpha line (lambda equals 121.6 nm) has 87.95 percent reflectance for the s-polarization case and 0.43 percent for the p-polarization case, with a degree of polarization of 99.03 percent. If a double reflection polarizer is made with this design, it will have a degree of polarization of 99.99 percent and s-polarization throughput of 77.35 percent.

Kim, Jongmin; Zukic, Muamer; Torr, Douglas G.

1993-01-01

50

Dynamic nuclear polarization from current-induced electron spin polarization  

NASA Astrophysics Data System (ADS)

Current-induced electron spin polarization is shown to produce nuclear hyperpolarization through dynamic nuclear polarization. Saturated fields of several millitesla are generated upon the application of an electric field over a time scale of 100 s in InGaAs epilayers and measured using optical Larmor magnetometry. We show that, in contrast to previous demonstrations of current-induced dynamic nuclear polarization, the direction of the current relative to the crystal axis and external magnetic field may be used to control the magnitude and direction of the saturation nuclear field.

Trowbridge, C. J.; Norman, B. M.; Kato, Y. K.; Awschalom, D. D.; Sih, V.

2014-08-01

51

Polarization maintaining fiber based ultra-high resolution spectral domain polarization sensitive optical coherence tomography  

PubMed Central

We present a new ultra high resolution spectral domain polarization sensitive optical coherence tomography (PS-OCT) system based on polarization maintaining (PM) fibers. The method transfers the principles of our previous bulk optic PS-OCT systems to a fiberized setup. The phase shift between the orthogonal polarization states travelling in the two orthogonal modes of the PM fiber is compensated by software in post processing. Thereby, the main advantage of our bulk optics setups, i.e. the use of only a single input polarization state to simultaneously acquire reflectivity, retardation, optic axis orientation, and Stokes vector, is maintained. The use of a broadband light source of 110 nm bandwidth provides improved depth resolution and smaller speckle size. The latter is important for improved resolution of depolarization imaging. We demonstrate our instrument for high-resolution PS-OCT imaging of the healthy human retina. PMID:20052196

2010-01-01

52

Polarization maintaining fiber based ultra-high resolution spectral domain polarization sensitive optical coherence tomography.  

PubMed

We present a new ultra high resolution spectral domain polarization sensitive optical coherence tomography (PS-OCT) system based on polarization maintaining (PM) fibers. The method transfers the principles of our previous bulk optic PS-OCT systems to a fiberized setup. The phase shift between the orthogonal polarization states travelling in the two orthogonal modes of the PM fiber is compensated by software in post processing. Thereby, the main advantage of our bulk optics setups, i.e. the use of only a single input polarization state to simultaneously acquire reflectivity, retardation, optic axis orientation, and Stokes vector, is maintained. The use of a broadband light source of 110 nm bandwidth provides improved depth resolution and smaller speckle size. The latter is important for improved resolution of depolarization imaging. We demonstrate our instrument for high-resolution PS-OCT imaging of the healthy human retina. PMID:20052196

Götzinger, Erich; Baumann, Bernhard; Pircher, Michael; Hitzenberger, Christoph K

2009-12-01

53

Spectral and Polarization Properties of Photospheric Emission from Stratified Jets  

NASA Astrophysics Data System (ADS)

We explore the spectral and polarization properties of photospheric emissions from stratified jets in which multiple components, separated by sharp velocity shear regions, are distributed in lateral directions. Propagation of thermal photons injected at a high optical depth region are calculated until they escape from the photosphere. It is found that the presence of the lateral structure within the jet leads to the nonthermal feature of the spectra and significant polarization signal in the resulting emission. The deviation from thermal spectra, as well as the polarization degree, tends to be enhanced as the velocity gradient in the shear region increases. In particular, we show that emissions from multicomponent jet can reproduce the typical observed spectra of gamma-ray bursts irrespective of the position of the observer when a velocity shear region is closely spaced in various lateral (?) positions. The degree of polarization associated with the emission is significant (>few percent) at a wide range of observer angles and can be higher than 30%.

Ito, Hirotaka; Nagataki, Shigehiro; Matsumoto, Jin; Lee, Shiu-Hang; Tolstov, Alexey; Mao, Jirong; Dainotti, Maria; Mizuta, Akira

2014-07-01

54

Complex variation of spectral line widths observed in polar corona  

NASA Astrophysics Data System (ADS)

Spectroscopic observations of the solar corona, using high spatial and spectral resolution 25cm coronagraph, at Norikura observatory, were made on large number of days during 2004 at the mid latitude and polar coronal regions. We have analyzed several raster scans that cover mid and high latitude regions on the off-limb corona in four bright emission lines of iron, namely, [Fe X] 6374 Å, [Fe XI]~7892~Å, [Fe XIII] 10747~Å, and [Fe XIV]~5303~Å. We find that the FWHM of red line increases with height and that of green line decreases with height as observed earlier, at equatorial regions. The comparison of line widths and their gradients with the results from equatorial regions indicate that these are higher for polar regions for the observed emission lines except for the green line. FWHM values show an increase towards poles in all the lines except for the green line which shows little or no change. Higher values of FWHM at polar regions may imply higher non-thermal velocities which could be linked to the solar wind, but the behavior of green emission line with almost same values of FWHM at equatorial and polar regions is surprising. This may also give some indications on the existence of preferential heating.

Prasad Samayamanthula, Krishna; Banerjee, Dipankar; Singh, Jagdev

2012-07-01

55

Cross borehole induced polarization to detect subsurface NAPL at the Savannah River Site, South Carolina  

E-print Network

Spectral induced polarization measurements were acquired in six cross-borehole panels within four boreholes at the Savannah River Site. The investigation was performed to delineate the presence of dense non-aqueous phase ...

Lambert, Michael B. (Michael Brian), 1980-

2003-01-01

56

Current-induced pseudospin polarization in silicene  

NASA Astrophysics Data System (ADS)

The pseudospin polarization induced by an external electric field in silicene in the presence of weakly spin-independent impurities is considered theoretically in the linear response regime based on Green's function method. We study the effects of the interplay between the sublattice potential and the intrinsic spin orbit coupling on the pseudospin polarization. We show that the pseudospin polarization perpendicular to the electric field is independent of the impurity parameter, while the pseudospin polarization in the direction of the electric field is sensitive to the impurity parameter. The dependences of the pseudospin polarizations on the chemical potential are studied.

Wang, Lei; Zhu, Guo-Bao

2014-09-01

57

Polarized spectral combs probe optical fiber surface plasmons.  

PubMed

The high-order cladding modes of conventional single mode fiber come in semi-degenerate pairs corresponding to mostly radially or mostly azimuthally polarized light. Using tilted fiber Bragg gratings to excite these mode families separately, we show how plasmonic coupling to a thin gold coating on the surface of the fiber modifies the effective indices of the modes differently according to polarization and to mode order. In particular, we show the existence of a single "apolarized" grating resonance, with equal effective index for all input polarization states. This special resonance provides direct evidence of the excitation of a surface plasmon on the metal surface but also an absolute wavelength reference that allows for the precise localization of the most sensitive resonances in refractometric and biochemical sensing applications. Two plasmon interrogation methods are proposed, based on wavelength and amplitude measurements. Finally, we use a biotin-streptavidin biomolecular recognition experiment to demonstrate that differential spectral transmission measurements of a fine comb of cladding mode resonances in the vicinity of the apolarized resonance provide the most accurate method to extract information from plasmon-assisted Tilted fiber Bragg gratings, down to pM concentrations and at least 10(-5) refractive index changes. PMID:23481763

Caucheteur, Christophe; Voisin, Valérie; Albert, Jacques

2013-02-11

58

Stokes vector measurement based on snapshot polarization-sensitive spectral interferometry.  

PubMed

This paper describes a Stokes vector measurement method based on a snapshot polarization-sensitive spectral interferometry. We measure perpendicular linearly polarized complex wave information of an anisotropic object in the spectral domain from which an accurate Stokes vector can be extracted. The proposed Stokes vector measurement method is robust to the object plane 3-D pose variation and external noise, and it provides a reliable snapshot solution in numerous spectral polarization-related applications. PMID:25090556

Kim, Daesuk; Seo, Yoonho; Jin, Moonseob; Yoon, Yonghee; Chegal, Won; Cho, Yong Jae; Cho, Hyun Mo; Abdelsalam, Dahi G; Magnusson, Robert

2014-07-14

59

[Design of full-polarized and multi-spectral imaging system based on LCVR].  

PubMed

A new full-polarized multi-spectral imaging system is described, which uses electronically controlled LCVR (liquid crystal variable retarder) to modulate the full-polarized state of light in the visible to IR range. The system consisted of optical lenses, LCVRs, filters and CCD. Firstly, the system structure, working theory and optical design are introduced in the present paper. A polarization calibration method is provided and the calibration system was set up, which realized high-precision polarization calibration using a small polarized source. Then, a field experiment with the imaging system was carried out. Polarized spectral images with higher spectral and spatial resolution were collected. Finally, the data acquired were rough processed to get polarization degree image of the targets. It is concluded that the experiment has proved that the imaging system is effective in obtaining full-polarized and multi- spectral data. The image captured by the system can be applied to object identification and object classification. PMID:21800604

Zhang, Ying; Zhao, Hui-jie; Cheng, Xuan; Xiong, Sheng-jun

2011-05-01

60

Optical CDMA with Embedded Spectral-Polarization Coding over Double Balanced Differential-Detector  

NASA Astrophysics Data System (ADS)

A spectral-polarization coding (SPC) optical code-division multiple-access (OCDMA) configuration structured over arrayed-waveguide grating (AWG) router is proposed. The polarization-division double balanced detector is adopted to execute difference detection and enhances system performance. The signal-to-noise ratio (SNR) is derived by taking the effect of PIIN into account. The result indicates that there would be up to 9-dB SNR improvement than the conventional spectral-amplitude coding (SAC) structures with Walsh-Hadamard codes. Mathematical deriving results of the SNR demonstrate the system embedded with the orthogonal state of polarization (SOP) will suppress effectively phase-induced intensity noise (PIIN). In addition, we will analyze the relations about bit error rate (BER) vs. the number of active users under the different encoding schemes and compare them with our proposed scheme. The BER vs. the effective power under the different encoding scheme with the same number of simultaneous active user conditions are also revealed. Finally, the polarization-matched factor and the difference between simulated and experimental values are discussed.

Huang, Jen-Fa; Yen, Chih-Ta; Chen, Bo-Hau

61

Non-Zeeman Circular Polarization of Molecular Maser Spectral Lines  

NASA Astrophysics Data System (ADS)

We apply the anisotropic resonant scattering model developed to explain the presence of non-Zeeman circular polarization signals recently detected in the 12CO (J = 2 ? 1) and (J = 1 ? 0) transitions in molecular clouds to Stokes V spectra of SiO v = 1 and v = 2, (J = 1 ? 0) masers commonly observed in evolved stars. It is found that the observed antisymmetric "S"- and symmetric "?"- or "?"-shaped spectral profiles naturally arise when the maser radiation scatters off populations of foreground molecules located outside the velocity range covered by the background maser radiation. Using typical values for the relevant physical parameters, it is estimated that magnetic field strengths on the order of a few times 15 mG are sufficient to explain the observational results found in the literature.

Houde, Martin

2014-11-01

62

OPTICAL POLARIZATION AND SPECTRAL VARIABILITY IN THE M87 JET  

SciTech Connect

During the last decade, M87's jet has been the site of an extraordinary variability event, with one knot (HST-1) increasing by over a factor 100 in brightness. Variability has also been seen on timescales of months in the nuclear flux. Here we discuss the optical-UV polarization and spectral variability of these components, which show vastly different behavior. HST-1 shows a highly significant correlation between flux and polarization, with P increasing from {approx}20% at minimum to >40% at maximum, while the orientation of its electric vector stayed constant. HST-1's optical-UV spectrum is very hard ({alpha}{sub UV-O} {approx} 0.5, F{sub {nu}}{proportional_to}{nu}{sup -{alpha}}), and displays 'hard lags' during epochs 2004.9-2005.5, including the peak of the flare, with soft lags at later epochs. We interpret the behavior of HST-1 as enhanced particle acceleration in a shock, with cooling from both particle aging and the relaxation of the compression. We set 2{sigma} upper limits of 0.5{delta} pc and 1.02c on the size and advance speed of the flaring region. The slight deviation of the electric vector orientation from the jet position angle (P.A.) makes it likely that on smaller scales the flaring region has either a double or twisted structure. By contrast, the nucleus displays much more rapid variability, with a highly variable electric vector orientation and 'looping' in the (I, P) plane. The nucleus has a much steeper spectrum ({alpha}{sub UV-O} {approx} 1.5) but does not show UV-optical spectral variability. Its behavior can be interpreted as either a helical distortion to a steady jet or a shock propagating through a helical jet.

Perlman, Eric S.; Cara, Mihai; Bourque, Matthew; Simons, Raymond C. [Department of Physics and Space Sciences, 150 W. University Blvd., Florida Institute of Technology, Melbourne, FL 32901 (United States); Adams, Steven C. [Department of Physics and Astronomy, University of Georgia, Athens, GA 30605 (United States); Harris, D. E. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Madrid, Juan P. [Center for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, VIC 3122 (Australia); Clausen-Brown, Eric [Department of Physics, Purdue University, West Lafayette, IN 47907 (United States); Cheung, C. C. [National Academy of Sciences, Washington, DC 20001 (United States); Stawarz, Lukasz [Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Georganopoulos, Markos [Department of Physics, University of Maryland-Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); Sparks, William B.; Biretta, John A., E-mail: eperlman@fit.edu [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2011-12-20

63

Optical Polarization and Spectral Variability in the M87 Jet  

NASA Technical Reports Server (NTRS)

During the last decade, M87's jet has been the site of an extraordinary variability event, with one knot (HST-1) increasing by over a factor 100 in brightness. Variability was also seen on timescales of months in the nuclear flux. Here we discuss the optical-UV polarization and spectral variability of these components, which show vastly different behavior. HST -1 shows a highly significant correlation between flux and polarization, with P increasing from approx 20% at minimum to > 40% at maximum, while the orientation of its electric vector stayed constant. HST-l's optical-UV spectrum is very hard (alpha(sub uv-0) approx. 0.5, F(sub v) varies as (v(exp -alpha)), and displays "hard lags" during epochs 2004.9-2005.5, including the peak of the flare, with soft lags at later epochs. We interpret the behavior of HST-1 as enhanced particle acceleration in a shock, with cooling from both particle aging and the relaxation of the compression. We set 2alpha upper limits of 0.5 delta parsecs and 1.02c on the size and advance speed of the flaring region. The slight deviation of the electric vector orientation from the jet PA, makes it likely that on smaller scales the flaring region has either a double or twisted structure. By contrast, the nucleus displays much more rapid variability, with a highly variable electric vector orientation and 'looping' in the (I, P) plane. The nucleus has a much steeper spectrum ((alpha(sub uv-0) approx. 1.5) but does not show UV-optical spectral variability. Its behavior can be interpreted as either a helical distortion to a steady jet or a shock propagating through a helical jet.

Perlman, Eric S.; Adams, Steven C.; Cara, Mihai; Bourque, Matthew; Harris, D. E.; Madrid, Juan P.; Simons, Raymond C.; Clausen-Brown, Eric; Cheung, C. C.; Stawarz, Lukasz; Georganopoulos, Markos; Sparks, William B.; Biretta, John A.

2011-01-01

64

Interference Thin Films for Spectral Filtering, Polarizing, Phase Retarding, and Intensity Splitting of FUV Radiation.  

NASA Astrophysics Data System (ADS)

The development of thin film technology for the far ultraviolet (FUV: 120~220 nm) has not progressed as rapidly as in the visible and infrared regions because substrate and thin film materials exhibit absorption characteristics that complicate the design process. Mathematically, these absorbing materials can be treated in the same manner as non-absorbing materials if a complex representation of the optical constants is used. Realization of higher throughput can be achieved by operating in a reflective rather than a transmissive mode. The spectral filter II -stack design method obtains a high reflectance by minimizing absorptance in the high refractive index layer while maintaining the constructive interference between reflected waves at the boundary of HL pairs. Reflective polarizers are designed by inducing transmission and absorption of the p-polarized light. Utilizing a MgF_2/Al/MgF _2 three layer structure on a thick Al layer as a substrate, high s-polarization reflectance (>88%) and a high degree of polarization (>99%) are obtained. Out-of-band rejection in the spectral filter and the degree of polarization in the polarizer are significantly improved by combining multiple reflectors in tandem. The high-low absorbing material boundaries in the MgF_2/Al/MgF_2 structure are also useful for obtaining phase retardance between s and p-polarized reflected fields. Two equations established by the ideal quarterwave retarder (QWR) requirement and electric field relations are used to determine the MgF_2 layer thicknesses to achieve excellent QWR performances. Calculated results show that a high reflectance for both polarizations (>80%) and almost 90^circ of phase retardance are possible. Discrepancies between the designed and measured polarizer performance are mainly caused by Al layer oxidation during fabrication in a conventional high vacuum chamber. XPS depth profiling is used to analyze the oxidation and the results show that oxidized layer thicknesses are greater than typically reported from optical techniques. A method is established to predict the maximum oxygen concentration at each Al interface based only on the pressure to rate ratio during film deposition. Along with polarizers and retarders, beam-splitters are also difficult to make due to absorption; and transparent conductive coatings have not been studied in the FUV region. A beam-splitter with improved TR product (transmittance times reflectance: TR = 0.20, 0.18) is designed with a dielectric multilayer. It is found that Cr is a significantly better film material for transparent conductive coatings than indium-tin-oxide (ITO) in the FUV region.

Kim, Jongmin

65

Polarization and spectral shift of benzophenone in supercritical water.  

PubMed

Monte Carlo simulation and quantum mechanics calculations based on the INDO/CIS and TD-DFT methods were utilized to study the solvatochromic shift of benzophenone when changing the environment from normal water to supercritical (P = 340.2 atm and T = 673 K) condition. Solute polarization increases the dipole moment of benzophenone, compared to gas phase, by 88 and 35% in normal and supercritical conditions, giving the in-solvent dipole value of 5.8 and 4.2 D, respectively. The average number of solute-solvent hydrogen bonds was analyzed, and a large decrease of 2.3 in normal water to only 0.8 in the supercritical environment was found. By using these polarized models of benzophenone in the two different conditions of water, we performed MC simulations to generate statistically uncorrelated configurations of the solute surrounded by the solvent molecules and subsequent quantum mechanics calculations on these configurations. When changing from normal to supercritical water environment, INDO/CIS calculations explicitly considering all valence electrons of the 235 solvent water molecules resulted in a solvatochromic shift of 1425 cm(-1) for the most intense pi-pi* transition of benzophenone, that is, slightly underestimated in comparison with the experimentally inferred result of 1700 cm(-1). TD-B3LYP/6-311+G(2d,p) calculations on the same configurations but with benzophenone electrostatically embedded in the 320 water molecules resulted in a solvatochromic shift of 1715 cm(-1) for this transition, in very good agreement with the experimental result. When using the unpolarized model of the benzophenone, this calculated solvatochromic shift was only 640 cm(-1). Additional calculations were also made by using BHandHLYP/6-311+G(2d,p) to analyze the effect of the asymptotic decay of the exchange functional. This study indicates that, contrary to the general expectation, there is a sizable solute polarization even in the low-density regime of supercritical condition and that the inclusion of this polarization is important for a reliable description of the spectral shifts considered here. PMID:19323549

Fonseca, T L; Georg, H C; Coutinho, K; Canuto, S

2009-04-30

66

Polarization and spectral sensitivity of single photoreceptors of the domestic cricket  

Microsoft Academic Search

The polarization and spectral sensitivity of single photoreceptors ofAcheta domesticus L. was measured. The morphological characteristics of the cricket rhabdome satisfy the conditions for a symmetrical model, for which the polarization sensitivity of a single photoreceptor is identically equal to the dichroism of a single microvillus. Characteristic curves of spectral sensitivity of all photoreceptors measured (24 cells) were similar and

F. G. Gribakin; T. M. Vishnevskaya; A. D. Polyanovskii

1979-01-01

67

Spectral domain polarization sensitive optical coherence tomography achieved by single camera detection  

Microsoft Academic Search

We present a spectral domain polarization sensitive optical coherence tomography (PSOCT) system that incorporates: 1) a spectrometer configured with a single line-scan camera for spectral interferogram detection, 2) a reference delay line assembly that provides a fixed optical pathlength delay between the lights of two orthogonal polarization states, and 3) a moving reference mirror that introduces a constant modulation frequency

Chuanmao Fan; Yi Wang; Ruikang K. Wang

2007-01-01

68

Ellipsoidal Universe Induces Large Scale CMB Polarization  

E-print Network

We calculate the large scale polarization of the cosmic microwave background induced by the anisotropy of the spatial geometry of our universe. Assuming an eccentricity at decoupling of about $0.64 10^{-2}$, we find $\\Delta T_{pol}/ T_0 \\simeq 0.53 10^{-6}$ quite close to the average level of polarization detected by the Wilkinson Microwave Anisotropy Probe.

Paolo Cea

2007-02-11

69

Birefringence imaging of biological tissue by spectral domain polarization sensitive optical coherence tomography  

Microsoft Academic Search

A spectral domain Polarization sensitive optical coherence tomography (SDPS-OCT) system has been developed to acquire depth images of biological tissues such as porcine tendon, rabbit eye. The Stocks vectors (I, Q, U, and V) of the backscattered light from the biological tissues have been reconstructed. Further, the phase retardation and polarization degree between the two orthogonal polarizing states have been

Zhijun Jing; Chuanmao Fan; Jingying Jiang; Qiang Gong; Zhenhe Ma; Fan Zhang; Jianquan Yao; R. K. Wang

2007-01-01

70

Spectral and polarization sensitivity of juvenile Atlantic salmon (Salmo salar): phylogenetic considerations.  

PubMed

We were interested in comparing the characteristics of polarization sensitivity in Atlantic salmon to those in Pacific salmon. Here we show that the common ancestor to the clade containing Salmo salar, Oncorhynchus mykiss, O. nerka, O. clarkii and Salvelinus fontinalis has the trait of ultraviolet polarization sensitivity. We examined spectral and polarization sensitivity of juvenile Atlantic salmon (Salmo salar) using both optic nerve compound action potential (CAP) and electroretinogram (ERG) recordings. Our experiments employed photic manipulation to adjust the sensitivity of the four cone mechanisms of Atlantic salmon. A spectrally broad background was used to ensure a contribution of all cone mechanisms to both spectral and polarization sensitivity. Chromatic adaptation was used to isolate the sensitivity of each of the four cone mechanisms for both spectral and polarization sensitivity. Under spectrally broad conditions, UV sensitive (UVS), mid wavelength sensitive (MWS) and long wavelength sensitive (LWS) cone mechanisms contributed to polarization sensitivity. CAP recordings produced the typical 'W' shaped polarization sensitivity curve reflecting two active polarization detectors with peaks at e-vector orientations of 0 deg, 90 deg and 180 deg, and troughs at 30 deg and 150 deg. ERG recordings produced a four-peaked polarization sensitivity curve reflecting two active polarization detectors and negative feedback activity, with peaks at e-vectors 0 deg, 45 deg, 90 deg, 135 deg and 180 deg, and troughs at 30 deg, 60 deg, 120 deg and 150 deg. Polarization-sensitivity measurements of isolated cone mechanisms revealed two orthogonal polarization detector mechanisms in Atlantic salmon, identical to that found in rainbow trout and other Pacific salmonid fishes. Moreover, under spectrally broad background conditions, CAP and ERG polarization sensitivity of Atlantic salmon did not differ significantly from that reported in Pacific salmonids. PMID:20802121

Hawryshyn, C W; Ramsden, S D; Betke, K M; Sabbah, S

2010-09-15

71

Deformation induced by polar motion  

NASA Astrophysics Data System (ADS)

Variations in the geocentric position of the earth's rotation axis (polar motion) cause deformation within the earth. The effects of this deformation on radial and horizontal positions of points on the earth's surface, on baseline lengths between those points, and on surface gravity are estimated. The effects of the oceans and of the earth's anelasticity on this deformation are found to be negligible. Peak-to-peak variations in radial motion are typically 10-20 mm over a year. Horizontal displacements are less than 7-8 mm. Variations in baseline length can be as large as 30-40 mm. Variations of up to 13 microgal in surface gravity are possible. These numbers are all small enough that they can probably not be used to learn about the earth. However, they are large enough to affect noticeably present high-quality geodetic observations.

Wahr, J. M.

1985-09-01

72

Polarization assisted fast data encoding and transmission using coherence based spectral anomalies  

NASA Astrophysics Data System (ADS)

Two methods for fast information encoding and free space communication are proposed, which are based on the rapid transitions in coherence-based (spatial and temporal) spectral anomalies called ‘spectral switches’. The information (data bits) could be encoded in terms of red and blue shifts in the source spectrum. The encoding process itself could be made fast by polarization assisted switching of spectral anomalies using a polarization selective device such as an electro-optic modulator. The advantages and limitations of this polarization based data processing mechanism are also discussed.

Kanseri, Bhaskar

2013-05-01

73

Induced polarization of ?(1116) in kaon electroproduction  

E-print Network

We have measured the induced polarization of the ${\\Lambda}(1116)$ in the reaction $ep\\rightarrow e'K^+{\\Lambda}$, detecting the scattered $e'$ and $K^+$ in the final state along with the proton from the decay $\\Lambda\\rightarrow p\\pi^-$.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy $W$ ($1.6\\leq W \\leq 2.7$ GeV) and covered the full range of the kaon production angle at an average momentum transfer $Q^2=1.90$ GeV$^2$.In this experiment a 5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the $W$ and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially $Q^2$ independent in our kinematic domain, suggesting that somewhere below the $Q^2$ covered here there must be a strong $Q^2$ dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved $s$-channel resonances.

M. Gabrielyan; B. A. Raue; D. S. Carman; K. Park; K. P. Adhikari; D. Adikaram; M. J. Amaryan; S. Anefalos Pereira; H. Avakian; J. Ball; N. A. Baltzell; M. Battaglieri; V. Baturin; I. Bedlinskiy; A. S. Biselli; J. Bono; S. Boiarinov; W. J. Briscoe; W. K. Brooks; V. D. Burkert; T. Cao; A. Celentano; S. Chandavar; G. Charles; P. L. Cole; M. Contalbrigo; O. Cortes; V. Crede; A. DAngelo; N. Dashyan; R. De Vita; E. De Sanctis; A. Deur; C. Djalali; D. Doughty; R. Dupre; L. El Fassi; P. Eugenio; G. Fedotov; S. Fegan; J. A. Fleming; T. A. Forest; B. Garillon; N. Gevorgyan; Y. Ghandilyan; G. P. Gilfoyle; K. L. Giovanetti; F. X. Girod; J. T. Goetz; E. Golovatch; R. W. Gothe; K. A. Griffioen; M. Guidal; L. Guo; K. Hafidi; H. Hakobyan; M. Hattawy; K. Hicks; D. Ho; M. Holtrop; S. M. Hughes; Y. Ilieva; D. G. Ireland; B. S. Ishkhanov; D. Jenkins; H. Jiang; H. S. Jo; K. Joo; D. Keller; M. Khandaker; W. Kim; F. J. Klein; S. Koirala; V. Kubarovsky; S. E. Kuhn; S. V. Kuleshov; P. Lenisa; W. I. Levine; K. Livingston; I. J. D. MacGregor; M. Mayer; B. McKinnon; C. A. Meyer; M. D. Mestayer; M. Mirazita; V. Mokeev; C. I. Moody; H. Moutarde; A Movsisyan; E. Munevar; C. Munoz Camacho; P. Nadel-Turonski; S. Niccolai; G. Niculescu; M. Osipenko; L. L. Pappalardo; R. Paremuzyan; E. Pasyuk; P. Peng; W. Phelps; J. J. Phillips; S. Pisano; O. Pogorelko; S. Pozdniakov; J. W. Price; S. Procureur; D. Protopopescu; D. Rimal; M. Ripani; A. Rizzo; F. Sabatie; C. Salgado; D. Schott; R. A. Schumacher; A. Simonyan; G. D. Smith; D. I. Sober; D. Sokhan; S. S. Stepanyan; S. Stepanyan; I. I. Strakovsky; S. Strauch; V. Sytnik; W. Tang; M. Ungaro; A. V. Vlassov; H. Voskanyan; E. Voutier; N. K. Walford; D. P. Watts; X. Wei; L. B. Weinstein; N. Zachariou; L. Zana; J. Zhang

2014-06-16

74

Induced polarization of ? (1116) in kaon electroproduction  

NASA Astrophysics Data System (ADS)

We have measured. the induced polarization of the ?(1116) in the reaction ep ?e'K+?, detecting the scattered e' and K+ in the final state along with the proton from the decay ? ?p?-. The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy W (1.6?W?2.7 GeV) and covered the full range of the kaon production angle at an average momentum transfer Q2=1.90GeV2. In this experiment a 5.50-GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the W and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially Q2 independent in our kinematic domain, suggesting that somewhere below the Q2 covered here there must be a strong Q2 dependence. Along with previously published photo- and electroproduction cross sections and polarization observables, these data are needed for the development of models, such as effective field theories, and as input to coupled-channel analyses that can provide evidence of previously unobserved s-channel resonances.

Gabrielyan, M.; Raue, B. A.; Carman, D. S.; Park, K.; Adhikari, K. P.; Adikaram, D.; Amaryan, M. J.; Anefalos Pereira, S.; Avakian, H.; Ball, J.; Baltzell, N. A.; Battaglieri, M.; Baturin, V.; Bedlinskiy, I.; Biselli, A. S.; Bono, J.; Boiarinov, S.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Cao, T.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Cortes, O.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; El Fassi, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Fleming, J. A.; Forest, T. A.; Garillon, B.; Gevorgyan, N.; Ghandilyan, Y.; Gilfoyle, G. P.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Golovatch, E.; Gothe, R. W.; Griffioen, K. A.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hattawy, M.; Hicks, K.; Ho, D.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Jenkins, D.; Jiang, H.; Jo, H. S.; Joo, K.; Keller, D.; Khandaker, M.; Kim, W.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Kuleshov, S. V.; Lenisa, P.; Levine, W. I.; Livingston, K.; MacGregor, I. J. D.; Mayer, M.; McKinnon, B.; Meyer, C. A.; Mestayer, M. D.; Mirazita, M.; Mokeev, V.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Munevar, E.; Munoz Camacho, C.; Nadel-Turonski, P.; Niccolai, S.; Niculescu, G.; Osipenko, M.; Pappalardo, L. L.; Paremuzyan, R.; Pasyuk, E.; Peng, P.; Phelps, W.; Phillips, J. J.; Pisano, S.; Pogorelko, O.; Pozdniakov, S.; Price, J. W.; Procureur, S.; Protopopescu, D.; Rimal, D.; Ripani, M.; Rizzo, A.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Simonyan, A.; Smith, G. D.; Sober, D. I.; Sokhan, D.; Stepanyan, S. S.; Stepanyan, S.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Tang, W.; Ungaro, M.; Vlassov, A. V.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.; CLAS Collaboration

2014-09-01

75

Spectral Mapping of the Intermediate Polar DQ Herculis  

NASA Astrophysics Data System (ADS)

We report an eclipse-mapping study of the intermediate polar DQ Her based on time-resolved optical spectroscopy (?? ~ 3800-5000 Å) covering four eclipses. The spectra were sliced into 295 narrow passbands in the continuum and in the lines, and the corresponding light curves were analyzed to solve for a set of monochromatic maps of the disk brightness distribution and for the flux of an additional uneclipsed component in each band. Eclipse maps of the He II ?4686 line indicate that an azimuthally and vertically extended bright spot at disk rim is an important source of the reprocessing of X-rays from the magnetic poles. The disk spectrum is flat with no Balmer or Helium lines in the inner regions, and shows double-peaked emission lines in the intermediate and outer disk regions, while the slope of the continuum becomes progressively redder with increasing radius. The inferred disk temperatures are in the range T ~= 13500-5000 K and can be reasonably well described by a steady-state disk with mass accretion rate of \\dot{M}=(2.7± 1.0)× 10^{-9} M_{?} yr^{-1}. A comparison of the radial intensity distribution for the Balmer lines reveals a linear correlation between the slope of the distribution and the transition energy. The spectrum of the uneclipsed light is dominated by Balmer and He I lines in emission (probably from the extended nova shell) with narrow absorption cores (likely from a collimated and optically thick wind from the accretion disk). The observed narrow and redshifted Ca II ?3934 absorption line in the total light spectra plus the inverse P-Cygni profiles of the Balmer and He II ?4686 emission lines in spectra of the asymmetric component indicate radial inflow of gas in the innermost disk regions and are best explained in terms of magnetically controlled accretion inside the white dwarf magnetosphere. We infer projected radial inflow velocities of ~200-500 km s-1, significantly lower than both the rotational and the free-fall velocities for the corresponding range of radii. A combined net emission He II plus H? low-velocity eclipse map reveals a twisted dipole emitting pattern near disk center. This is interpreted as being the projection of accretion curtains onto the orbital plane at two specific spin phases, as a consequence of the selection in velocity provided by the spectral eclipse mapping.

Saito, R. K.; Baptista, R.; Horne, K.; Martell, P.

2010-06-01

76

Methods in arthropod retinography for evaluation of spectral polarization sensitivity  

NASA Astrophysics Data System (ADS)

We describe apparatus and methods to measure the sensitivity of arthropod eyes to wavelength and polarization. While these general methods are well-known in the retinography community, they are less familiar to the general optics community. Measurement of polarization sensitivity is particularly uncommon even among retinographers, and our research plan and example results are detailed.

Wehling, Martin F.; Goldstein, Dennis H.

2010-04-01

77

Mask-induced polarization effects at high numerical aperture  

E-print Network

Mask-induced polarization effects at high numerical aperture Andrew Estroff Yongfa Fan Anatoly at higher numerical apertures NAs due to mask-induced polarization effects. We study how different photomask.21.240.32. Terms of Use: http://spiedl.org/terms #12;pass. The electric field of the TE polarized light induces

Zanibbi, Richard

78

DC Resistivity and Induced Polarization Methods  

Microsoft Academic Search

Direct current (DC) resistivity (here referred to as resistivity) and induced polarization (IP) methods allow, respectively, the determination of the spatial distribution of the low-frequency\\u000a resistive and capacitive characteristics of soil. Since both properties are affected by lithology, pore fluid chemistry, and\\u000a water content (see Chapter 4 of this volume), these methods have significant potential for hydrogeophysical applications.\\u000a The methods

Andrew Binley; Andreas Kemna

79

Proton emission induced by polarized photons  

E-print Network

The proton emission induced by polarized photons is studied in the energy range above the giant resonance region and below the pion emission threshold. Results for the 12C, 16O and 40Ca nuclei are presented. The sensitivity of various observables to final state interaction, meson exchange currents and short range correlations is analyzed. We found relevant effects due to the virtual excitation of the $\\Delta$ resonance.

M. Anguiano; G. Co'; A. M. Lallena

2006-08-29

80

Spectral morphological analysis of skin lesions with a polarization multispectral dermoscope.  

PubMed

Dermoscopy is the conventional technique used for the clinical inspection of human skin lesions. However, the identification of diagnostically relevant morphologies can become a complex task. We report on the development of a polarization multispectral dermoscope for the in vivo imaging of skin lesions. Linearly polarized illumination at three distinct spectral regions (470, 530 and 625 nm), is performed by high luminance LEDs. Processing of the acquired images, by means of spectral and polarization filtering, produces new contrast images, each one specific for melanin absorption, hemoglobin absorption, and single scattering. Analysis of such images could facilitate the identification of pathological morphologies. PMID:23482017

Kapsokalyvas, Dimitrios; Bruscino, Nicola; Alfieri, Domenico; de Giorgi, Vincenzo; Cannarozzo, Giovanni; Cicchi, Riccardo; Massi, Daniela; Pimpinelli, Nicola; Pavone, Francesco S

2013-02-25

81

Polarization studies of Zeeman affected spectral lines using the MSFC magnetograph  

NASA Technical Reports Server (NTRS)

The Marshall Space Flight Center (MSFC) vector magnetograph records polarization images of absorption lines that are sensitive to magnetic fields. A method is presented for analyzing the Stokes spectral-line profiles of a photospheric Fe I absorption line (5250.2 A) which is influenced by the Zeeman effect. Using nonlinear least-square optimization, the observed Stokes profiles are compared with those generated from the theoretical solution of the polarized radiative transfer equations. The optimization process accounts for the spectral convolution of the source and the MSFC vector magnetograph. The resulting physical properties of the active region producing the polarized light are discussed.

Balasubramaniam, K. S.; West, E. A.

1990-01-01

82

A Compact Imaging Detector of Polarization and Spectral Content  

NASA Technical Reports Server (NTRS)

A new type of image detector will simultaneously analyze the polarization of light at all picture elements in a scene. The integrated Dual Imaging Detector (IDID) consists of a polarizing beam splitter bonded to a charge-coupled device (CCD), with signal-analysis circuitry and analog-to-digital converters, all integrated on a silicon chip. The polarizing beam splitter can be either a Ronchi ruling, or an array of cylindrical lenslets, bonded to a birefringent wafer. The wafer, in turn, is bonded to the CCD so that light in the two orthogonal planes of polarization falls on adjacent pairs of pixels. The use of a high-index birefringent material, e.g., rutile, allows the IDID to operate at f-numbers as high as f/3.5. Other aspects of the detector are discussed.

Rust, D. M.; Kumar, A.; Thompson, K. E.

1993-01-01

83

A study of spectral-polarization characteristics of plant canopies using land-based remote sensing  

NASA Astrophysics Data System (ADS)

The study addresses reflection and spectral-polarization characteristics of forest stands and farm crops obtained under field conditions. The study of the reflection properties of farm crops shows that during the summer plant growing season, the major factors influencing the plant canopy reflectance are morpho-physiological parameters, plant architectonics, solar elevation h0, and viewing angle. The crop reflectance minimum was recorded at viewing angles 25-30° with respect to the nadir. Coniferous and broadleaf forest stands had similar reflectance spectra of polarized light. The polarized component was smaller for all coniferous stands than for broadleaf ones. For broad-leaved farm crops (wheat and corn), the polarized component of the spectral brightness coefficients had a greater influence on the plant reflectance in the red and near-infrared spectral regions, ?>720 nm.

Sid`ko, A. F.; Botvich, I. Yu.; Pisman, T. I.; Shevyrnogov, A. P.

2013-11-01

84

Theoretical and experimental study of time domain-induced polarization in water-saturated sands  

Microsoft Academic Search

A theoretical model of spectral-induced polarization (IP) of sand is presented. In the proposed model, contacts of sand grains and intergrain solution-filled space are considered as electrical current passages of varying thickness, which differ in values of ion transport number. Ion-selective narrow passages are considered as active zones, large passages as passive. The proposed model describes spectral IP characteristics for

K. Titov; V. Komarov; V. Tarasov; A. Levitski

2002-01-01

85

Double-pass self-spectral-calibration of a polarization state analyzer.  

PubMed

We present a new method that allows efficient spectral calibration for a polarization state analyzer. The procedure does not require any additional polarization optical element other than the polarization state analyzer itself. It uses a double-pass technique that can be achieved up to a very good precision. The method is illustrated using real measurements done at several wavelengths with a rotating wave plate polarization state analyzer. Alignment of axis as well as true retardation at a specific wavelength are easily obtained by a standard function fitting. PMID:22297366

Zallat, Jihad; Torzynski, Marc; Lallement, Alex

2012-02-01

86

EFFICIENT SPECTRAL-GALERKIN METHODS III: POLAR AND ...  

E-print Network

c 1997 Society for Industrial and Applied Mathematics. Vol. 18, No. ... have important applications in many fields of science and engineering, especially in ..... in [15] for more details on this procedure for a similar problem. 2.3. ...... [9] D. GOTTLIEB AND S. A. ORSZAG, Numerical Analysis of Spectral Methods: Theory and Ap-.

1999-10-21

87

Polarization of four-wave mixing with electromagnetically induced transparency  

NASA Astrophysics Data System (ADS)

The dependence of four-wave mixing (FWM) generated in Rubidium (Rb) vapor with electromagnetically induced transparency (EIT) window on polarizations of the incident fields is studied both theoretically and experimentally. The polarization properties of FWM signal under diverse laser polarization configurations are studied and compared. The results indicate that FWM signal is linear polarized when all incident fields are linear polarized. However, FWM becomes elliptical polarized if any incident field is elliptical polarized. Moreover, the polarizations of the incident fields also influence the dressing effect of the coupling field on FWM process. As the polarization of coupling field (or probe field) varying from linear to circular, the dressing effect gets stronger. By controlling the polarizations of the incident beams polarizations, we can manipulate the polarization state of FWM signal and the dressing effect as well.

Cheng, Xuemei; Du, Yigang; Zhang, Yanpeng; Wang, Zhiguo; Miao, Yizhu; Ren, Zhaoyu; Bai, Jintao

2012-10-01

88

Spectral-temporal-polarization encoding of photons for multi-user secure quantum communication  

NASA Astrophysics Data System (ADS)

We describe a Quantum Key Distribution protocol that combines temporal-, spectraland polarization-encoding of photons for secure communication over an interconnected network of users. Temporal encoding is used to identify a user's location or address on the network. Polarization encoding is used to generate private cryptographic key. Polarization encoded information is locally and randomly generated by users and exchanged only over a dedicated secure channel. Spectral encoding allows for the detection of eavesdropping and tampering by a malicious agent. Temporal-spectral signals sent from the network administrator (Alice) to a user are bright light source. On the other hand spectral-temporal signal from a network user (Bob) to the administrator (Alice) are single photons. Signals are sent across the network as ordered light pairs. The ordering format is randomly chosen and are revealed only at the time of key selection between the parties so that a secure one-time cryptographic pad can be generated

Donkor, Eric

2014-05-01

89

Feature Extraction Techniques for the Analysis of Spectral Polarization Profiles  

E-print Network

This paper introduces a novel feature extraction technique for the analysis of spectral line Stokes profiles. The procedure is based on the use of an auto-associative artificial neural network containing non-linear hidden layers. The neural network extracts a small subset of parameters from the profiles (features), from which it is then able to reconstruct the original profile. This new approach is compared to two other procedures that have been proposed in previous works, namely principal component analysis and Hermitian function expansions. Depending on the target application, each one of these three techniques has some advantages and disadvantages, which are discussed here.

H. Socas-Navarro

2004-10-23

90

High speed spectral domain polarization sensitive optical coherence tomography of the human retina  

Microsoft Academic Search

We developed a high-speed polarization sensitive optical coherence tomography (PS-OCT) system for retinal imaging based on spectral domain OCT. The system uses two spectrometers, one for each polarization channel, that operate in parallel at 20000 A-lines\\/s each. It provides reflectivity, retardation, and cumulative optic axis orientation simultaneously. We present our instrument and discuss the requirements for the alignment of the

Erich Götzinger; Michael Pircher; Christoph K. Hitzenberger

2005-01-01

91

Magnetic-Field-Induced Electric Polarization in Multiferroic Nanostructures  

Microsoft Academic Search

Magnetic-field-induced electric polarization in nanostructured multiferroic composite films was studied by using the Green's function approach. The calculations showed that large magnetic-field-induced polarization could be produced in multiferroic nanostructures due to enhanced elastic coupling interaction. Especially, the 1-3 type films with ferromagnetic nanopillars embedded in a ferroelectric matrix exhibited large magnetic-field-induced polarization responses, while the 2-2 type films with ferroelectric

Ce-Wen Nan; Gang Liu; Yuanhua Lin; Haydn Chen

2005-01-01

92

Birefringence imaging of human skin by polarization-sensitive spectral interferometric optical coherence tomography  

Microsoft Academic Search

We have developed a spectral interferometric optical coherence tomography (OCT) system with polarization sensitivity that is able to measure a two-dimensional tomographic image by means of one-dimensional mechanical scanning. Our system, which has an axial resolution of 32 mum, calculates the distribution of each element of the Müller matrix of a measured object from 16 OCT images. The OCT system

Y. Yasuno; S. Makita; Y. Sutoh; M. Itoh; T. Yatagai

2002-01-01

93

Spectral domain polarization sensitive optical coherence tomography based on the two-phase method  

Microsoft Academic Search

In this talk, a spectral domain polarization sensitive optical coherence tomography (SDPS-OCT) system has been developed so as to obtain high scan speed, high dynamic range and high sensitivity, and simultaneously get birefringence contrast of some biological tissue. To reduce corruption of the DC and autocorrelation terms to images, we introduce the two phase method. The stocks vectors (I, Q,

Chuanmao Fan; Zhijun Jing; Jingying Jiang; Qiang Gong; Zhenhe Ma; Fan Zhang; Jianquan Yao; R. K. Wang

2007-01-01

94

Metamaterial polarization spectral filter: Isolated transmission line at any prescribed wavelength  

E-print Network

Metamaterial polarization spectral filter: Isolated transmission line at any prescribed wavelength k0 where birefringence @n ¼ no � ne changes its sign, see Fig. 1(a). At this wavelength, known as the "isoindex wavelength" birefringence vanishes and the crystal becomes isotropic. At wavelengths away from

Zheludev, Nikolay

95

Radiation induced polarization in CdTe detectors  

Microsoft Academic Search

Polarization induced by irradiation with intense gamma ray sources has been studied in chlorine-compensated CdTe detectors. The influence of several parameters, such as applied field strength, temperature and incident photon flux, on the polarization effect have been investigated. A relationship was found between the degree of polarization, detector efficiency and detector leakage current.

D. Vartsky; M. Goldberg; Y. Eisen; Y. Shamai; R. Dukhan; P. Siffert; J. M. Koebel; R. Regal; J. Gerber

1988-01-01

96

Scintillation-Induced Circular Polarization in Pulsars and Quasars  

E-print Network

We present a physical interpretation for the generation of circular polarization resulting from the propagation of radiation through a magnetized plasma in terms of a rotation measure gradient, or `Faraday wedges'. Criteria for the observability of scintillation-induced circular polarization are identified. Application of the theory to the circular polarization in pulsars and compact extragalactic sources is discussed.

J. -P. Macquart; D. B. Melrose

2000-07-28

97

Temporal Spectral Shift and Polarization of a Band-splitting Solar Type II Radio Burst  

NASA Astrophysics Data System (ADS)

In many type II solar radio bursts, the fundamental and/or the harmonic branches of the bursts can split into two almost parallel bands with similar spectral shapes and frequency drifts. However, the mechanisms accounting for this intriguing phenomenon remain elusive. In this study, we report a special band-splitting type II event in which spectral features appear systematically earlier on the upper band (with higher frequencies) than on the lower band (with lower frequencies) by several seconds. Furthermore, the emissions carried by the splitting band are moderately polarized with the left-hand polarized signals stronger than the right-hand ones. The polarization degree varies in a range of -0.3 to -0.6. These novel observational findings provide important constraints on the underlying physical mechanisms of band-splitting of type II radio bursts.

Du, Guohui; Chen, Yao; Lv, Maoshui; Kong, Xiangliang; Feng, Shiwei; Guo, Fan; Li, Gang

2014-10-01

98

Are high polarization quasars and BL Lacertae objects really different? A study of the optical spectral properties.  

NASA Astrophysics Data System (ADS)

The continuum and emission lines properties of a sample of 73 blazars is studied, investigating differences and similarities among normal low-polarization quasars (LPQ), radio-loud high polarized quasars (HPQ), and BL Lacertae objects (BLL). We found that at variance with LPQ, most HPQ have power law optical continua (fnu_{prop.to}?alpha^ ) with no indication of blue bumps or strong FeII and Balmer emission. Comparison of LPQ with blazars, considered as a class including both HPQ and BLL, confirms and put on firm statistical bases that the optical continuum of blazars (?_O_=-1.00 +/-0.09) is significantly steeper than that of LPQ (?_O_~-0.5). On the other hand the average spectral index for the HPQ and BLL subsamples is rather similar (=-1.01+/-0.17 and =-0.99+/-0.11). In the ?_O_-?_RX_ plane HPQ do not split in two distinct groups as do BLL, which spilt in Radio (RBL) and X-ray selected (XBL) objects. All HPQ cluster together in the same region occupied by RBL, while XBL are clearly distinguished. A significant correlation is found between the maximum percentage of optical polarization and both ?_O_ and ?_RX_ , the less polarized object having the steeper spectral index. The comparison of emission line luminosities shows that LPQ have on average stronger lines (~ a factor of 6) with respect to blazars. Comparing HPQ and RBL we show they exhibit similar range of line luminosity, BL Lacs being just the objects with lines of smaller equivalent width as directly induced by the e.w.<5Å definition criteria. This leads us to conclude that from the point of view of optical spectral properties HPQ and RBL are quite similar objects while XBL may be different.

Scarpa, R.; Falomo, R.

1997-09-01

99

Microtubule-induced cortical cell polarity  

Microsoft Academic Search

Most cells are polarized. Embryonic and stem cells can use their polarity to generate cell diversity by asymmet- ric cell division, whereas differentiated cells use their polarity to execute specific functions. For example, fi- broblasts form an actin-rich leading edge required for cell migration, neurons form distinctive axonal and dendritic compartments important for directional signaling, and epithelial cells have apical

Sarah E. Siegrist; Chris Q. Doe

2007-01-01

100

Biochemistry 1984, 23, 1935-1939 1935 Chemically Induced Dynamic Nuclear Polarization Studies of Yeast  

E-print Network

Biochemistry 1984, 23, 1935-1939 1935 Chemically Induced Dynamic Nuclear Polarization Studies* ABSTRACT: Chemically induced dynamicnuclear polarization (CIDNP) has been observed from yeast t). The NMR method chemically induced dynamic nuclear polarization (CIDNP) is well suited to probing

Boxer, Steven G.

101

Spectral domain polarization-sensitive optical coherence tomography at 850 nm  

Microsoft Academic Search

Spectral-Domain Polarization-Sensitive Optical Coherence Tomography (SD-PS-OCT) is a technique developed to measure the thickness and birefringence of the nerve fiber layer in vivo as a tool for the early diagnosis of glaucoma. A clinical SD-PS-OCT system was developed and scans were made around the optic nerve head (ONH) using ten concentric circles of increasing diameter. One healthy volunteer was imaged.

Barry Cense; Teresa C. Chen; Mircea Mujat; Chulmin Joo; Taner Akkin; B. H. Park; Mark C. Pierce; Andy Yun; Brett E. Bouma; Guillermo J. Tearney; Johannes F. de Boer

2005-01-01

102

Retrieval and analysis of a polarized high-spectral-resolution lidar for profiling aerosol optical properties.  

PubMed

Taking advantage of the broad spectrum of the Cabannes-Brillouin scatter from atmospheric molecules, the high spectral resolution lidar (HSRL) technique employs a narrow spectral filter to separate the aerosol and molecular scattering components in the lidar return signals and therefore can obtain the aerosol optical properties as well as the lidar ratio (i.e., the extinction-to-backscatter ratio) which is normally selected or modeled in traditional backscatter lidars. A polarized HSRL instrument, which employs an interferometric spectral filter, is under development at the Zhejiang University (ZJU), China. In this paper, the theoretical basis to retrieve the aerosol lidar ratio, depolarization ratio and extinction and backscatter coefficients, is presented. Error analyses and sensitivity studies have been carried out on the spectral transmittance characteristics of the spectral filter. The result shows that a filter that has as small aerosol transmittance (i.e., large aerosol rejection rate) and large molecular transmittance as possible is desirable. To achieve accurate retrieval, the transmittance of the spectral filter for molecular and aerosol scattering signals should be well characterized. PMID:23736562

Liu, Dong; Yang, Yongying; Cheng, Zhongtao; Huang, Hanlu; Zhang, Bo; Ling, Tong; Shen, Yibing

2013-06-01

103

Development of the ZJU polarized near-infrared high spectral resolution lidar  

NASA Astrophysics Data System (ADS)

Quantitative measurements of atmospheric aerosol optical properties are required for studies of the Earth's radiation budget and climate change. Taking advantage of the broad spectrum of the Cabannes-Brillouin scattering from atmospheric molecules, the high spectral resolution lidar (HSRL) technique employs a narrow spectral filter to reject the aerosol Mie scattering component in the lidar return signals. Therefore, an HSRL can directly measure the extinction and backscatter coefficient as well as the lidar ratio. Since the backscattering signal is proportional to 1/?4, it presents high requirements for the spectral filter to build a near-infrared HSRL. The atomic/molecular absorption filters are limited by the wavelength and it is also challenging for Fabry-Perot interferometers (FPI) due to their small field of view(FOV). The field-widened Michelson interferometer, which has a large FOV, is considered to be a good candidate for the spectral filter of near-infrared HSRL. A polarized near-infrared HSRL instrument, which employs a field-widened Michelson interferometer as the spectral filter, is under development at the Zhejiang University (ZJU), China. In this paper, the methodology and design process of the instrument will be described in detail. The capability of the HSRL in determining the properties of the atmosphere will be addressed. The retrieval of the aerosol optical properties, such as extinction-to-backscatter ratio and aerosol depolarization ratio, will be presented. Sensitivity of the aerosol retrieval to errors in characterizing the spectral filter will also be investigated.

Liu, Dong; Yang, Yongying; Cheng, Zhongtao; Huang, Hanlu; Zhang, Bo; Shen, Yibing

2013-09-01

104

Nuclear reactivity control using laser induced polarization.  

National Technical Information Service (NTIS)

A control element for reactivity control of a fission source provides an atomic density of (sup 3)He in a control volume which is effective to control criticality as the (sup 3)He is spin-polarized. Spin-polarization of the (sup 3)He affects the cross sec...

C. D. Bowman

1989-01-01

105

CMB polarization induced by stochastic magnetic fields  

E-print Network

The complete calculation of the CMB polarization observables (i.e. E- and B-modes) is reported within the conventional $\\Lambda$CDM paradigm supplemented by a stochastic magnetic field. Intriguing perspectives for present and forthcoming CMB polarization experiments are outlined.

Massimo Giovannini; Kerstin E. Kunze

2008-04-14

106

Lambda Polarization in Lepton Induced Reactions  

E-print Network

Different phenomenological approaches for Lambda and Lambda-bar polarization in polarized semi-inclusive deep inelastic scattering and electron-positron annihilation at Z^0 pole are considered. Current and future experiments will soon provide accurate enough data to study spin phenomena in these reactions and distinguish between various models.

A. M. Kotzinian

1997-09-05

107

Theoretical and experimental studies of the spectral changes of a polychromatic partially coherent radially polarized beam.  

PubMed

In a recent publication (Appl. Phys. Lett. 100 (2012) 051108), a monochromatic partially coherent radially polarized (RP) beam was generated experimentally. In this paper, we analyze the spectral changes of a polychromatic partially coherent RP beam focused by a thin lens for the first time, and compare with that of a focused scalar polychromatic GSM beam. Furthermore, we report experimental generation of a polychromatic partially coherent RP beam and carry out experimental measurement of the spectral changes of such beam focused by a thin lens. Our results show that the behavior of the spectral changes of a focused polychromatic partially coherent RP beam is different from that of a focused scalar polychromatic GSM beam. Our experimental results are consistent with the theoretical predictions. PMID:24514286

Zhu, Shijun; Zhu, Xianglong; Liu, Lin; Wang, Fei; Cai, Yangjian

2013-11-18

108

Nuclear reactivity control using laser induced polarization  

DOEpatents

A control element for reactivity control of a fission source provides an atomic density of .sup.3 He in a control volume which is effective to control criticality as the .sup.3 He is spin-polarized. Spin-polarization of the .sup.3 He affects the cross section of the control volume for fission neutrons and hence, the reactivity. An irradiation source is directed within the .sup.3 He for spin-polarizing the .sup.3 He. An alkali-metal vapor may be included with the .sup.3 He where a laser spin-polarizes the alkali-metal atoms which in turn, spin-couple with .sup.3 He to spin-polarize the .sup.3 He atoms.

Bowman, Charles D. (Los Alamos, NM)

1991-01-01

109

Nuclear reactivity control using laser induced polarization  

DOEpatents

A control element for reactivity control of a fission source provides an atomic density of .sup.3 He in a control volume which is effective to control criticality as the .sup.3 He is spin-polarized. Spin-polarization of the .sup.3 He affects the cross section of the control volume for fission neturons and hence, the reactivity. An irradiation source is directed within the .sup.3 He for spin-polarizing the .sup.3 He. An alkali-metal vapor may be included with the .sup.3 He where a laser spin-polarizes the alkali-metal atoms which in turn, spin-couple with .sup.3 He to spin-polarize the .sup.3 He atoms.

Bowman, Charles D. (Los Alamos, NM)

1990-01-01

110

Speckle noise reduction in high speed polarization sensitive spectral domain optical coherence tomography.  

PubMed

We present a high speed polarization sensitive spectral domain optical coherence tomography system based on polarization maintaining fibers and two high speed CMOS line scan cameras capable of retinal imaging with up to 128 k A-lines/s. This high imaging speed strongly reduces motion artifacts and therefore averaging of several B-scans is possible, which strongly reduces speckle noise and improves image quality. We present several methods for averaging retardation and optic axis orientation, the best one providing a 5 fold noise reduction. Furthermore, a novel scheme of calculating images of degree of polarization uniformity is presented. We quantitatively compare the noise reduction depending on the number of averaged frames and discuss the limits of frame numbers that can usefully be averaged. PMID:21934820

Götzinger, Erich; Pircher, Michael; Baumann, Bernhard; Schmoll, Tilman; Sattmann, Harald; Leitgeb, Rainer A; Hitzenberger, Christoph K

2011-07-18

111

Spectral decomposition of the stellar kinematics in the polar disk galaxy NGC 4650A  

NASA Astrophysics Data System (ADS)

Context. The prototype of polar ring galaxies NGC 4650A contains two main structural components, a central spheroid, which is the host galaxy, and an extended polar disk. Both photometric and kinematic studies revealed that these two components co-exist on two different planes within the central regions of the galaxy. Aims: The aim of this work is to study the spectroscopic and kinematic properties of the host galaxy and the polar disk in the central regions of NGC 4650A by disentangling their contributions to the observed galaxy spectrum. Methods: We applied the spectral decomposition technique introduced in previous works to long-slit spectroscopic observations in the CaII triplet region. We focused the analysis along the PA = 152° that corresponds to the photometric minor axis of the host galaxy, where the superimposition of the two components is more relevant and the spectral decomposition is necessary. We aim to disentangle the stars that move in the equatorial plane of the host galaxy from those that move in the meridan plane, which is along the polar disk. Results: We successfully disentangled the spectra of the two structural components of NGC 4650A and measured their line-of-sight velocity and velocity dispersion profiles, and the stellar content along PA = 152°. The host galaxy shows significant rotation along its photometric minor axis, indicating that the gravitational potential is not axisymmetric. The polar disk shows a kinematic decoupling: the inner regions counter-rotating with respect the outer-regions and the host spheroid. This suggests a complex formation history for the polar disk, characterised by mass accretion with decoupled angular momenta.

Coccato, L.; Iodice, E.; Arnaboldi, M.

2014-09-01

112

Analysis of random induced cross polarization  

NASA Astrophysics Data System (ADS)

Streamlined radomes will always introduce depolarization because of the fact that any material surface viewed at an oblique angle has different transmission coefficients for fields polarized parallel and perpendicular to the plane of incidence, a phenomenon known as divorce. The cross polarized fields are similar in nature to those responsible for Condon lobes of parabolic reflectors, and which are known to make those antennas susceptible to cross polarization jamming. The relative strength of those lobes is directly related to the amount of divorce, and is quite sensitive to the phase difference of parallel and perpendicular transmission coefficients. A mere 20 deg of phase divorce has a comparable effect to 3 dB of amplitude divorce. This paper presents a detailed analysis for general radome shapes, based on geometrical optics (ray tracing). Example results are presented for conical and tangent ogive radome geometries used in conjunction with a circular-aperture antenna that is mechanically scanned. The results show that when the antenna is scanned off axis, the cross polarized pattern changes from a Condon lobe structure to a difference pattern in the direction orthogonal to the axis of scan, e.g.: under azimuth scanning the cross polarized sum pattern resembles an elevation difference pattern, while the cross polarized elevation difference resembles a sum beam. Hence, interference in the cross polarization will introduce a tracking error in the direction orthogonal to the scan plane.

McGrath, Daniel T.

1992-03-01

113

Spin transfer and polarization of antihyperons in lepton induced reactions  

E-print Network

We study the polarization of antihyperon in lepton induced reactions such as $e^+e^-\\to\\bar H+X$ and $l+p\\to l'+\\bar H+X$ with polarized beams using different models for spin transfer in high energy fragmentation processes. We compare the results with the available data and those for hyperons. We make predictions for future experiments.

Hui Dong; Jian Zhou; Zuo-tang Liang

2005-06-22

114

Poling-induced waveguide polarizers in electrooptic polymers  

Microsoft Academic Search

In order to demonstrate polymeric waveguide polarizers, photobleached polymer waveguides supporting both TE and TM modes are integrated with poling induced polymer waveguides that support either TE or TM modes. Fabrication parameters like UV exposures and poling voltages are controlled to reduce excess losses due to the mode profile mismatch between the connected waveguides. A TM-pass polarizer is realized by

Min-Cheol Oh; Sang-Yung Shin; Wol-Yon Hwang; Jang-Joo Kim

1996-01-01

115

Three-Dimensional Induced Polarization Data Inversion for Complex Resistivity.  

National Technical Information Service (NTIS)

The conductive and capacitive material properties of the subsurface can be quantified through the frequency-dependent complex resistivity. However, the routine three-dimensional interpretation of voluminous induced polarization (IP) data sets still poses ...

G. A. Newman, K. H. Williams, M. Commer, S. S. Hubbard

2011-01-01

116

Shock-Induced Polarization of Plexiglas and Polystyrene.  

National Technical Information Service (NTIS)

The theory describing the electric polarization produced in certain dielectrics by the passage of a shock front has been generalized to take account of relaxationeffects. The shock-induced displacement current is described in terms of three parameters: P ...

F. E. Allison, G. E. Hauver

1964-01-01

117

Stress-induced single-polarization single-mode fiber  

Microsoft Academic Search

The stress-induced birefringence in a single-mode optical fiber with an elliptical inner cladding or an elliptical core is calculated. The design of a fiber is proposed in which only one linearly polarized mode can propagate.

W. Eickhoff

1982-01-01

118

GLOBAL SPECTRAL ENERGY DISTRIBUTION OF THE CRAB NEBULA IN THE PROSPECT OF THE PLANCK SATELLITE POLARIZATION CALIBRATION  

SciTech Connect

Within the framework of the Planck satellite polarization calibration, we present a study of the Crab Nebula spectral energy distribution (SED) over more than six decades in frequency ranging from 1 to 10{sup 6} GHz (from 299 to 2.99 x 10{sup -4} mm). The Planck satellite mission observes the sky from 30 to 857 GHz (from 9.99 to 0.3498 mm) and therefore we focus on the millimeter region. We use radio and submillimeter data from the WMAP satellite between 23 and 94 GHz (from 13 to 3.18 mm), from the Archeops balloon experiment between 143 (2.1 mm) and 545 GHz (0.55 mm), and a compendium of other Crab Nebula observations. The Crab SED is compared to models including three main components: synchrotron that is responsible for the emission at low and high frequencies, dust that explains the excess of flux observed by the IRAS satellite, and an extra component on the millimeter regime. From this analysis, we conclude that the unpolarized emission of the Crab Nebula at microwave and millimeter wavelengths is the same synchrotron emission as the one observed in the radio domain. Therefore, we expect the millimeter emission of the Crab Nebula to be polarized with the same degree of polarization and orientation as the radio emission. We set upper limits on the possible errors induced by any millimeter extra component on the reconstruction of the degree and angle of polarization at the percent level as a maximum. This result strongly supports the choice by the Planck collaboration of the Crab Nebula emission for performing polarization cross-checks in the range 30 (299 mm) to 353 GHz (0.849 mm).

MacIas-Perez, J. F.; Mayet, F.; Aumont, J. [LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, 53, av. des Martyrs, 38026 Grenoble (France); Desert, F.-X. [Laboratoire d'Astrophysique, Obs. de Grenoble, BP 53, 38041 Grenoble Cedex 9 (France)

2010-03-01

119

Tunnelling effects induced transparent polarization manipulation  

NASA Astrophysics Data System (ADS)

We proposed, designed and fabricated a three-layer metamaterial consisting of two layers of electrically spilt ring resonators (SRRs) and a layer of the subwavelength metal mesh symmetrically sandwiched between the two SRR layers. The numerical simulations and experimental measurements revealed that the linear-to-circular, linear-to-elliptical and linear-to-linear polarization controls can be accomplished by simply altering the polarization angle of incident waves. This transparent polarization conversion/rotator is related to the tunnelling effects of electromagnetic (EM) waves for both incident polarizations. The physical mechanism of tunnelling effect is also investigated both numerically and experimentally, and results have shown that the high-? SRR layer facilitates the EM waves to propagate through the metal mesh layer without attenuation. In addition, the magnetic field distribution in the structure is analysed to further illustrate this tunnelling phenomenon. The thickness of this polarization device is ultra-thin compared with the wavelength, which provides a new way for designing the miniaturized and light weight quarter wave plates or other polarization manipulation devices.

Dong, Liang; Zhu, Lei

2014-04-01

120

Spectral fluorescence and polarization characteristics of Z,Z-bilirubin IX?  

NASA Astrophysics Data System (ADS)

We have studied the spectral fluorescence and polarization characteristics of Z,Z-bilirubin IX?, at room temperature in chloroform and in aqueous buffer medium, within an equilibrium complex with human serum albumin (HSA), and also under low temperature conditions (T = -100°C) in isobutyl alcohol. We have observed a bathochromic shift of the fluorescence spectra, which is most pronounced for the bilirubin-albumin complex. The following are considered as possible reasons for the observed dependence of the position of the fluorescence (fluorescence excitation) spectra on the excitation (detection) wavelength: structural and spectral differences between the chromophores making up the bilirubin molecule; conformational heterogeneity of the pigment in solution; a contribution to the fluorescence from molecules which have not completed the vibrational relaxation process; inhomogeneous orientational broadening of the levels; heterogeneity of the microenvironment of the chromophores in the protein matrix. We show that polarized fluorescence of bilirubin occurs at room temperature, due to the anomalously short fluorescence lifetime ? (picosecond or subpicosecond ranges). Despite such a short ?, the absorption and emission polarization spectra suggest the presence of intramolecular nonradiative singlet-singlet energy transfer when bilirubin is excited to high vibrational sublevels of the S1 state (degree of polarization p = 0.11-0.12). When fluorescence is excited on the long-wavelength slope of the absorption band, no transfer occurs: the degree of polarization (p = 0.46-0.47) is close to the limiting value (p = 0.50). We discuss the question of the role played by exciton interactions between chromophores in the bilirubin molecule when it is excited.

Plavskii, V. Yu.; Mostovnikov, V. A.; Mostovnikova, G. R.; Tret'yakova, A. I.

2007-01-01

121

Spectral decomposition of the stellar kinematics in the polar disk galaxy NGC 4650A  

E-print Network

Context. The prototype of Polar Ring Galaxies NGC 4650A contains two main structural components, a central spheroid, which is the host galaxy, and an extended polar disk. Both photometric and kinematic studies revealed that these two components co-exist on two different planes within the central regions of the galaxy. Aims. The aim of this work is to study the spectroscopic and kinematic properties of the host galaxy and the polar disk in the central regions of NGC 4650A by disentangling their contributions to the observed galaxy spectrum. Methods. We applied the spectral decomposition technique introduced in previous works to long-slit spectroscopic observations in the CaII triplet region. We focused the analysis along the PA = 152 that corresponds to the photometric minor axis of the host galaxy, where the superimposition of the two components is more relevant and the spectral decomposition is necessary. We aim to disentangle the stars that move in the equatorial plane of the host galaxy from those that mov...

Coccato, L; Arnaboldi, M

2014-01-01

122

Mask-induced polarization effects at high NA  

NASA Astrophysics Data System (ADS)

It is important to understand how a photomask will polarize incident radiation. This paper presents data collected on binary mask and various attenuated phase shifting mask materials, feature sizes, duty ratios, and illumination schemes via rigorous coupled wave analysis, extinction spectroscopy, and 193nm lithographic evaluation. Additionally, the result of polarization effects due to the photomask on imaging has been studied. It was found that in the majority of the cases, higher NA led to greater polarization effects. All mask materials predominantly pass the TM polarization state for the 0 order, whereas different materials and duty ratios affect the polarization of the first diffracted orders differently. The polarization effects contributed by mask materials being considered for use in high NA imaging systems need to be examined. The degree of polarization as a function of n and k is presented, providing an introduction to the desirable properties of future mask materials. Materials with higher refractive indices and lower extinction coefficients tend to pass more of the TM polarization state, which is undesirable. Materials with lower indices and relatively wide range of extinction coefficients pass more TE polarized radiation. The duty ratio, critical dimension, mask material, material thickness, and illumination scheme all influence mask induced polarization effects.

Estroff, Andrew; Fan, Yongfa; Bourov, Anatoly; Smith, Bruce; Foubert, Philippe; Leunissen, L. H. A.; Philipsen, Vicky; Aksenov, Yuri

2005-05-01

123

Temporal and spectral studies of high-order harmonics generated by polarization-modulated infrared fields  

SciTech Connect

The temporal confinement of high harmonic generation (HHG) via modulation of the polarization of the fundamental pulse is studied in both temporal and spectral domains. In the temporal domain, a collinear cross-correlation setup using a 40 fs IR pump for the HHG and a 9 fs IR pulse to probe the generated emission is used to measure the XUV pulse duration. The observed temporal confinement is found to be consistent with theoretical predictions. An increased confinement is observed when a 9 fs pulse is used to generate the harmonics. An important spectral broadening, including a continuum background, is also measured. Theoretical calculations show that with 10 fs driving pulses, either one or two main attosecond pulses are created depending on the value of the carrier envelope phase.

Sola, I. J.; Zaier, A.; Cormier, E.; Mevel, E.; Constant, E. [Centre Lasers Intenses et Applications (CELIA), Domaine du Haut-Carre, Universite Bordeaux 1, 351 Cours de la Liberation, 33405 Talence (France); Lopez-Martens, R.; Johnsson, P.; Varju, K.; Mauritsson, J.; L'Huillier, A. [Department of Physics, Lund Institute of Technology, P.O. Box 118, S-221 00 Lund (Sweden); Strelkov, V. [General Physics Institute of Russian Academy of Sciences, 38, Vavilova st., Moscow 119991 (Russian Federation)

2006-07-15

124

Antiproton polarization induced by lepton interactions  

E-print Network

We present expressions for electromagnetic helicity amplitudes and spin observables for any elastic spin 1/2 - spin 1/2 scattering to first order in QED. In particular all electromagnetic helicity amplitudes and spin observables for elastic antiproton-electron and antiproton-proton scattering via single t-channel photon exchange are presented. Spin observables are required to describe the rate of increase of polarization in spin filtering. The PAX collaboration at GSI Darmstadt is interested in the buildup of polarization of an antiproton beam by repeated interaction with a hydrogen gas target in a storage ring. In order for the beam particles to remain in the ring after scattering it is important to consider small angle scattering, hence small momentum transfer t. In the low momentum transfer region electromagnetic effects dominate the hadronic effects. Of immediate importance is whether the polarization of an antiproton beam can be built up by spin filtering off polarized electrons either in a target or in a beam. We present the theoretical background for this discussion.

D. S. O'Brien; N. H. Buttimore

2006-09-22

125

Polarized spectral properties of Sm3+:LiLuF4 crystal for visible laser application  

NASA Astrophysics Data System (ADS)

A Sm3+-doped LiLuF4 single crystal was grown by the vertical Bridgman-Stockbarge technique. Polarized absorption spectra, polarized fluorescence spectra, and fluorescence lifetime of the Sm3+:LiLuF4 crystal were recorded at room temperature. Based on the Judd-Ofelt theory, spectral parameters of the Sm3+:LiLuF4 crystal were calculated. Emission cross sections for the 4G5/2 ? 6HJ (J = 5/2, 7/2, 9/2, and 11/2) transitions with special interest for visible laser application were obtained by the Füchtbauer-Ladenburg formula. The results indicate that the Sm3+:LiLuF4 crystal may be a potential laser gain medium operating in visible region pumped by diode lasers around 401 nm.

Wang, G. Q.; Gong, X. H.; Lin, Y. F.; Chen, Y. J.; Huang, J. H.; Luo, Z. D.; Huang, Y. D.

2014-11-01

126

Vacuum polarization induced by a uniformly accelerated charge  

E-print Network

We consider a point charge fixed in the Rindler coordinates which describe a uniformly accelerated frame. We determine an integral expression of the induced charge density due to the vacuum polarization at the first order in the fine structure constant. In the case where the acceleration is weak, we give explicitly the induced electrostatic potential.

B. Linet

1995-03-30

127

Polarization-induced ?-holes and hydrogen bonding.  

PubMed

The strong collinear polarizability of the A-H bond in A-H···B hydrogen bonds is shown to lead to an enhanced ?-hole on the donor hydrogen atom and hence to stronger hydrogen bonding. This effect helps to explain the directionality of hydrogen bonds, the well known cooperative effect in hydrogen bonding, and the occurrence of blue-shifting. The latter results when significant additional electron density is shifted into the A-H bonding region by the polarization effect. The shift in the A-H stretching frequency is shown to depend essentially linearly on the calculated atomic charge on the donor hydrogen for all donors in which A belongs to the same row of the periodic table. A further result of the polarization effect, which is also expected for other ?-hole bonds, is that the strength of the non-covalent interaction depends strongly on external electric fields. PMID:22015592

Hennemann, Matthias; Murray, Jane S; Politzer, Peter; Riley, Kevin E; Clark, Timothy

2012-06-01

128

White dwarf mass estimation with a new comprehensive X-ray spectral model of intermediate polars  

NASA Astrophysics Data System (ADS)

A white dwarf (WD) mass is important astrophysical quantity because the WD explodes as a type Ia supernova when its mass reaches the Chandrasekhar mass limit of 1.4 solar mass. Many WD masses in intermediate polars (IPs) were measured with their X-ray spectra emitted from plasma flows channeled by strong magnetic fields of the WDs. For the WD mass estimation, multi-temperature X-ray spectral models have been used which made by summing up X-ray spectra emitted from the top to the bottom of the plasma flow. However, in previous studies, distributions of physical quantities such as temperature and density etc., which are base of the X-ray spectral model, were calculated with assumptions of accretion rate per unit area (call "specific accretion rate") a = 1 g cm(-2) s(-1) and cylindrical geometry for the plasma flows. In fact, a part of the WD masses estimated with the X-ray spectral model is not consistent with that dynamically measured. Therefore, we calculated the physical quantity distributions with the dipolar geometry and the wide range of the specific accretion rate a = 0.0001 - 100 g cm(-2) s(-1) . The calculations showed that the geometrical difference changes the physical quantity distributions and the lower specific accretion rate leads softer X-ray spectrum under a critical specific accretion rate. These results clearly indicate that the previous assumptions are not good approximation for low accretion IPs. We made a new spectral model of the plasma flow with our physical quantity distributions and applied that to Suzaku observations of high and low accretion rate IPs V1223 Sagittarii and EX Hydrae. As a results, our WD masses are almost consistent with the those dynamically measured. We will present the summary of our theoretical calculation and X-ray spectral model, and application to the {¥it Suzaku} observations.

Hayashi, Takayuki; Ishida, Manabu

129

Electronic transport through nuclear-spin-polarization-induced quantum wire  

E-print Network

Electron transport in a new low-dimensional structure - the nuclear spin polarization induced quantum wire (NSPI QW) is theoretically studied. In the proposed system the local nuclear spin polarization creates the effective hyperfine field which confines the electrons with the spins opposite to the hyperfine field to the regions of maximal nuclear spin polarization. The influence of the nuclear spin relaxation and diffusion on the electron energy spectrum and on the conductance of the quantum wire is calculated and the experimental feasibility is discussed.

Yu. V. Pershin; S. N. Shevchenko; I. D. Vagner; P. Wyder

2001-09-25

130

Spin-Polarized Electron Induced Asymmetric Reactions in Chiral Molecules  

NASA Astrophysics Data System (ADS)

Understanding the origin of chirality in nature has been an active area of research since the time of Pasteur. In this chapter we examine one possible route by which this asymmetry could have arisen, namely chiral-specific chemistry induced by spin-polarized electrons. The various sources of spin-polarized electrons (parity violation, photoemission, and secondary processes) are discussed. Experiments aimed at exploring these interactions are reviewed starting with those based on the Vester-Ulbricht hypothesis through recent studies of spin polarized secondary electrons from a magnetic substrate. We will conclude with a discussion of possible new avenues of research that could impact this area.

Rosenberg, Richard A.

131

Polar Lipids of Burkholderia pseudomallei Induce Different Host Immune Responses  

PubMed Central

Melioidosis is a disease in tropical and subtropical regions of the world that is caused by Burkholderia pseudomallei. In endemic regions the disease occurs primarily in humans and goats. In the present study, we used the goat as a model to dissect the polar lipids of B. pseudomallei to identify lipid molecules that could be used for adjuvants/vaccines or as diagnostic tools. We showed that the lipidome of B. pseudomallei and its fractions contain several polar lipids with the capacity to elicit different immune responses in goats, namely rhamnolipids and ornithine lipids which induced IFN-?, whereas phospholipids and an undefined polar lipid induced strong IL-10 secretion in CD4+ T cells. Autologous T cells co-cultured with caprine dendritic cells (cDCs) and polar lipids of B. pseudomallei proliferated and up-regulated the expression of CD25 (IL-2 receptor) molecules. Furthermore, we demonstrated that polar lipids were able to up-regulate CD1w2 antigen expression in cDCs derived from peripheral blood monocytes. Interestingly, the same polar lipids had only little effect on the expression of MHC class II DR antigens in the same caprine dendritic cells. Finally, antibody blocking of the CD1w2 molecules on cDCs resulted in decreased expression for IFN-? by CD4+ T cells. Altogether, these results showed that polar lipids of B. pseudomallei are recognized by the caprine immune system and that their recognition is primarily mediated by the CD1 antigen cluster. PMID:24260378

Gonzalez-Juarrero, Mercedes; Mima, Naoko; Trunck, Lily A.; Schweizer, Herbert P.; Bowen, Richard A.; Dascher, Kyle; Mwangi, Waithaka; Eckstein, Torsten M.

2013-01-01

132

Three-dimensional induced polarization data inversion for complex resistivity  

SciTech Connect

The conductive and capacitive material properties of the subsurface can be quantified through the frequency-dependent complex resistivity. However, the routine three-dimensional (3D) interpretation of voluminous induced polarization (IP) data sets still poses a challenge due to large computational demands and solution nonuniqueness. We have developed a flexible methodology for 3D (spectral) IP data inversion. Our inversion algorithm is adapted from a frequency-domain electromagnetic (EM) inversion method primarily developed for large-scale hydrocarbon and geothermal energy exploration purposes. The method has proven to be efficient by implementing the nonlinear conjugate gradient method with hierarchical parallelism and by using an optimal finite-difference forward modeling mesh design scheme. The method allows for a large range of survey scales, providing a tool for both exploration and environmental applications. We experimented with an image focusing technique to improve the poor depth resolution of surface data sets with small survey spreads. The algorithm's underlying forward modeling operator properly accounts for EM coupling effects; thus, traditionally used EM coupling correction procedures are not needed. The methodology was applied to both synthetic and field data. We tested the benefit of directly inverting EM coupling contaminated data using a synthetic large-scale exploration data set. Afterward, we further tested the monitoring capability of our method by inverting time-lapse data from an environmental remediation experiment near Rifle, Colorado. Similar trends observed in both our solution and another 2D inversion were in accordance with previous findings about the IP effects due to subsurface microbial activity.

Commer, M.; Newman, G.A.; Williams, K.H.; Hubbard, S.S.

2011-03-15

133

PHYSICAL REVIEW B 85, 094107 (2012) Interfacial polarization and pyroelectricity in antiferrodistortive structures induced  

E-print Network

coupling cannot induce polarization inside easy twins and antiphase boundaries; their polarization is the following: the biquadratic coupling induces bistable ferroelectric polarization inside hard antiphase, polarization, and magnetization, which can couple to induce new phenomena not present in the relevant bulk

Chen, Long-Qing

134

Surface discharge plasma induced by spontaneous polarization switching  

NASA Astrophysics Data System (ADS)

A flashover plasma has been induced by spontaneous polarization switching on a polar surface of the ferroelectric crystal triglycine sulphate (TGS). The effect has not been observed in the paraelectric phase. The threshold switching voltage for a surface flashover ignition was as low as 100 V for pulsed and ac voltage. A mechanism of plasma initiation on a ferroelectric surface is proposed. It is assumed that the plasma is ignited by electron emission initiated by polarization switching. Subsequent electron avalanching occurs as a result of the high potential gradient along the ferroelectric surface caused by inhomogeneous polarization switching. Electrons and ions with energies up to several hundreds of eV were been recorded due to a high surface potential of the switched ferroelectric.

Shur, D.; Rosenman, G.; Krasik, Ya. E.

1997-02-01

135

Induced interaction in a spin-polarized Fermi gas  

SciTech Connect

We study the effect of the induced interaction on the superfluid transition temperature of a spin-polarized Fermi gas. In the BCS limit, the polarization is very small in the superfluid state, and the effect of the induced interaction is almost the same as in the spin-balanced case. The temperature T{sub t} and the polarization P{sub t} of the tricritical point are both reduced from mean-field results by a factor about 2.22. This reduction is also significant beyond the BCS limit. In the unitary limit, we find (P{sub t},T{sub t}/T{sub F})=(0.42,0.16), in comparison with mean-field and experimental results.

Yu Zengqiang; Yin Lan [School of Physics, Peking University, Beijing 100871 (China)

2010-07-15

136

Spectral and polarization modulation of quantum dot emission in a one-dimensional liquid crystal photonic cavity  

NASA Astrophysics Data System (ADS)

We demonstrate spectral and polarization modulation of chemically synthesized core shell CdSe/ZnS quantum dots (QDs) embedded in a one-dimensional photonic cavity formed by a cholesteric liquid crystal (CLC) matrix. A Cano-wedge cell varies the pitch of the CLC leading to the formation of Grandjean steps. This spatially tunes the photonic stop band, changing the resonance condition and continuously altering both the emission wavelength and polarization state of the QD ensemble. Using high resolution spatially- and spectrally-resolved photoluminescence measurements we find that the emission is elliptically polarized and that the tilt of the ellipse, while dependent on the emission wavelength, additionally varies with distance across the Grandjean steps. This work opens up the possibility of designing new QD based optical devices, such as tunable single photon sources, where spatial control of wavelength and polarization of the embedded QDs would allow great flexibility and added functionalities.

Rodarte, Andrea; Gray, C.; Hirst, L. S.; Ghosh, S.

2012-02-01

137

Spectral and polarization modulation of quantum dot emission in a one-dimensional liquid crystal photonic cavity  

NASA Astrophysics Data System (ADS)

We demonstrate spectral and polarization modulation of chemically synthesized core shell CdSe/ZnS quantum dots (QDs) embedded in a one-dimensional photonic cavity formed by a cholesteric liquid crystal (CLC) matrix. A Cano-wedge cell varies the pitch of the CLC leading to the formation of Grandjean steps. This spatially tunes the photonic stop band, changing the resonance condition and continuously altering both the emission wavelength and polarization state of the QD ensemble. Using high resolution spatially- and spectrally-resolved photoluminescence measurements we find that the emission is elliptically polarized and that the tilt of the ellipse, while dependent on the emission wavelength, additionally varies with distance across the Grandjean steps. This work opens up the possibility of designing new QD based optical devices, such as tunable single photon sources, where spatial control of wavelength and polarization of the embedded QDs would allow great flexibility and added functionalities.

Rodarte, Andrea L.; Gray, C.; Hirst, L. S.; Ghosh, S.

2011-11-01

138

Spectral and polarization modulation of quantum dot emission in a one-dimensional liquid crystal photonic cavity  

NASA Astrophysics Data System (ADS)

We demonstrate spectral and polarization modulation of chemically synthesized core-shell CdSe/ZnS quantum dots (QDs) embedded in a one-dimensional photonic cavity formed by a cholesteric liquid crystal (CLC) matrix. A Cano-wedge cell varies the pitch of the CLC leading to the formation of Grandjean steps. This spatially tunes the photonic stop band, changing the resonance condition and continuously altering both the emission wavelength and polarization state of the QD ensemble. Using high resolution spatially and spectrally resolved photoluminescence measurements, we find that the emission is elliptically polarized and that the tilt of the ellipse, while dependent on the emission wavelength, additionally varies with distance across the Grandjean steps. This work opens up the possibility of designing new QD based optical devices, such as tunable single photon sources, where spatial control of wavelength and polarization of the embedded QDs would allow great flexibility and added functionalities.

Rodarte, A. L.; Gray, C.; Hirst, L. S.; Ghosh, S.

2012-01-01

139

Eustatic sea level fluctuations induced by polar wander  

Microsoft Academic Search

It is shown here that polar wander of a viscoelastic, stratified earth can induce global sea level fluctuations comparable to the short-term component in eustatic sea-level curves. The sign of these fluctuations, which are very sensitive to the rheological stratification, depends on the geographical location of the observation point; rises and falls in sea level can thus be coeval in

Roberto Sabadini; Carlo Doglioni; David A. Yuen

1990-01-01

140

General solutions for stress-induced polarization in optical fibers  

Microsoft Academic Search

General solutions of thermal stresses and material birefringence in polarization-maintaining optical fibers are presented. The solutions give the stresses and birefringence at every point in the cross section of various fibers. The fundamental solution of the stress field is constructed by using the complex variable method in elasticity. When the cores, inner claddings, or stress-inducing regions are ellipses, circles, or

Kun-Hsieh Tsai; Kyung-Suk Kim; T. F. Morse

1991-01-01

141

Large-field high-speed polarization sensitive spectral domain OCT and its applications in ophthalmology  

PubMed Central

We present a novel spectral domain polarization sensitive OCT system (PS-OCT) that operates at an A-scan rate of 70 kHz and supports scan angles of up to 40° × 40°. The high-speed imaging allows the acquisition of up to 1024 × 250 A-scans per 3D scan, which, together with the large field of view, considerably increases the informative value of the images. To demonstrate the excellent performance of the new PS-OCT system, we imaged several healthy volunteers and patients with various diseases such as glaucoma, AMD, Stargardt’s disease, and albinism. The results are compared with clinically established methods such as scanning laser polarimetry and autofluorescence. PMID:23162711

Zotter, Stefan; Pircher, Michael; Torzicky, Teresa; Baumann, Bernhard; Yoshida, Hirofumi; Hirose, Futoshi; Roberts, Philipp; Ritter, Markus; Schutze, Christopher; Gotzinger, Erich; Trasischker, Wolfgang; Vass, Clemens; Schmidt-Erfurth, Ursula; Hitzenberger, Christoph K.

2012-01-01

142

Large-field high-speed polarization sensitive spectral domain OCT and its applications in ophthalmology.  

PubMed

We present a novel spectral domain polarization sensitive OCT system (PS-OCT) that operates at an A-scan rate of 70 kHz and supports scan angles of up to 40° × 40°. The high-speed imaging allows the acquisition of up to 1024 × 250 A-scans per 3D scan, which, together with the large field of view, considerably increases the informative value of the images. To demonstrate the excellent performance of the new PS-OCT system, we imaged several healthy volunteers and patients with various diseases such as glaucoma, AMD, Stargardt's disease, and albinism. The results are compared with clinically established methods such as scanning laser polarimetry and autofluorescence. PMID:23162711

Zotter, Stefan; Pircher, Michael; Torzicky, Teresa; Baumann, Bernhard; Yoshida, Hirofumi; Hirose, Futoshi; Roberts, Philipp; Ritter, Markus; Schütze, Christopher; Götzinger, Erich; Trasischker, Wolfgang; Vass, Clemens; Schmidt-Erfurth, Ursula; Hitzenberger, Christoph K

2012-11-01

143

Effect of surface induced nucleation of ferroelastic domains on polarization switching in constrained ferroelectrics  

E-print Network

Effect of surface induced nucleation of ferroelastic domains on polarization switching polarization switching in constrained ferroelectrics is investigated using the time-dependent Ginzburg. A square-shaped finite sized constrained ferroelectric system with vanishing surface polarization

Cao, Wenwu

144

Curvature-induced polarization in carbon nanoshells Traian Dumitricaa *, Chad M. Landis, Boris I. Yakobson  

E-print Network

Curvature-induced polarization in carbon nanoshells Traian Dumitricaa *, Chad M. Landis, Boris I Abstract We investigate the normal polarization induced by bending of graphite shells, which the curvature-induced polarization into the rolled graphite sheet by calculating the magnitude of the induced

145

Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography  

PubMed Central

Abstract. We present spectral domain polarization-sensitive optical coherence tomography (SD PS-OCT) imaging of peripheral nerves. Structural and polarization-sensitive OCT imaging of uninjured rat sciatic nerves was evaluated both qualitatively and quantitatively. OCT and its functional extension, PS-OCT, were used to image sciatic nerve structure with clear delineation of the nerve boundaries to muscle and adipose tissues. A long-known optical effect, bands of Fontana, was also observed. Postprocessing analysis of these images provided significant quantitative information, such as epineurium thickness, estimates of extinction coefficient and birefringence of nerve and muscle tissue, frequency of bands of Fontana at different stretch levels of nerve, and change in average birefringence of nerve under stretched condition. We demonstrate that PS-OCT combined with regular-intensity OCT (compared with OCT alone) allows for a clearer determination of the inner and outer boundaries of the epineurium and distinction of nerve and muscle based on their birefringence pattern. PS-OCT measurements on normal nerves show that the technique is promising for studies on peripheral nerve injury. PMID:22612135

Islam, M. Shahidul; Oliveira, Michael C.; Wang, Yan; Henry, Francis P.; Randolph, Mark A.; Park, B. Hyle; de Boer, Johannes F.

2012-01-01

146

Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography.  

PubMed

We present spectral domain polarization-sensitive optical coherence tomography (SD PS-OCT) imaging of peripheral nerves. Structural and polarization-sensitive OCT imaging of uninjured rat sciatic nerves was evaluated both qualitatively and quantitatively. OCT and its functional extension, PS-OCT, were used to image sciatic nerve structure with clear delineation of the nerve boundaries to muscle and adipose tissues. A long-known optical effect, bands of Fontana, was also observed. Postprocessing analysis of these images provided significant quantitative information, such as epineurium thickness, estimates of extinction coefficient and birefringence of nerve and muscle tissue, frequency of bands of Fontana at different stretch levels of nerve, and change in average birefringence of nerve under stretched condition. We demonstrate that PS-OCT combined with regular-intensity OCT (compared with OCT alone) allows for a clearer determination of the inner and outer boundaries of the epineurium and distinction of nerve and muscle based on their birefringence pattern. PS-OCT measurements on normal nerves show that the technique is promising for studies on peripheral nerve injury. PMID:22612135

Islam, M Shahidul; Oliveira, Michael C; Wang, Yan; Henry, Francis P; Randolph, Mark A; Park, B Hyle; de Boer, Johannes F

2012-05-01

147

Soft X-Ray Spectral Analysis of the North Polar Spur  

NASA Astrophysics Data System (ADS)

I present a soft X-ray spectral observation of the North Polar Spur (NPS), an enhanced feature in the Soft X-ray Background. The observation was made with a Charge Coupled Device (CCD) aboard a sounding rocket on May 2, 1997. CCD temperature during flight was -72°C, approximately 15° higher than optimal. A total of 330 seconds of data was collected. The spectrum, in the 0.22-10 keV energy range, was analyzed using the XSPEC data package. The data were fit by a three component model: an absorbed power law representing the extragalactic emission, a thermal plasma model representing the foreground emission from the Local Hot Bubble and a thermal plasma model representing emission from the North Polar Spur. The extragalactic component was fit with an absorbed power law, using a column density of 2 × 1020cm -2. The best fit gave a spectral index of 1.391 and a normalization of 11.11. The local component was fit with a Raymond and Smith thermal plasma model. The best fit resulted in a temperature of 1.5 × 106 K and an emission measure of 6.76 × 103cm-6 pc. The NPS component was fit with an absorbed Raymond and Smith thermal plasma model with a temperature of 3.5 × 106 K and an emission measures of 3.53 × 103cm-6 pc. The fit was significantly improved with the addition of Gaussians at energies of known astrophysical lines corresponding to N VII, Ne IX, Mg XI and Si Ly?. It was also significantly improved when the abundances of N, O, Ne, Ar, Fe, and Ni were allowed to vary using a variable Raymond and Smith thermal plasma model for the NPS component. Both fits are evidence of abundance variations in the North Polar Spur. An NEI (nonequilibrium ionization) model for the NPS component did not result in a significant improvement of the fit, suggesting that the NPS plasma is already in collisional ionization equilibrium.

Cawley, Laura Joan

148

Induced Polarization Responses of the Specimen with Sulfide Ore Minerals  

NASA Astrophysics Data System (ADS)

Basic data of the physical properties of the rocks is required to effectively interpret geologic structures and mineralized zones in study areas from the geophysical data in the field of subsurface investigations and mineral resources explorations. In this study, the spectral induced polarization (SIP) measurement system in the laboratory was constructed to obtain the IP characteristics of the specimen with sulfide ore minerals. The SIP measurement system consists of lab transmitter for electrical current transmission, and GDP-32 for current receiver. The SIP system employs 14 steps of frequencies from 0.123 to 1,024 Hz, and uses copper sulfate solution as an electrolyte. The SIP data for system verification was acquired using a measurement system of parallel circuit with fixed resistance and condenser. This measured data was in good agreement with Cole-Cole model data. First of all, the experiment on the SIP response was conducted in the laboratory with the mixture of glass beads and pyrite powders for ore grade assessment using characteristics of IP response of the rocks. The results show that the phase difference of IP response to the frequency is nearly proportional to the weight content of pyrite, and that the dominant frequency of the IP response varies with the size of the pyrite powder. Subsequently, the specimens used for SIP measurement are slate and limestone which were taken from drilling cores and outcrops of skarn ore deposits. All specimens are cylindrical in shape, with a diameter of 5 cm and a length of 10 cm. When measuring SIP of water-saturated specimens, the specimen surface is kept dry, tap water is put into the bottom of sample holder and a lid is closed. It is drawn that the SIP characteristics of the rocks show the phase difference depends on the amount of the sulfide minerals. The phase difference did not occur with frequencies applied in the absence of sulfide minerals in the rock specimens. On the contrary, the rock specimens containing sulfide minerals such as galena, sphalerite, pyrrhotite, chalcopyrite, pyrite show large phase differences with frequencies applied. In particular, the slate specimens with skarn Pb-Zn show high IP responses to the frequencies applied since the specimens contain high amount of the sulfide minerals. The specimens of other rocks in the skarn ore deposits, on the other hand, do not provide the detectable IP responses since the rocks consist mostly of silicate minerals. The phase difference derived from the frequency applied was converted to the data for ore grade since the phase of SIP response shows high relationship with the ore grade.

Park, S.; Sung, N. H.

2012-04-01

149

Induced Polarization Surveying for Acid Rock Screening in Highway Design  

NASA Astrophysics Data System (ADS)

Highway and pipeline construction agencies have become increasingly vigilant in their efforts to avoid cutting through sulphide-bearing bedrock that has potential to produce acid rock drainage. Blasting and fragmentation of such rock increases the surface area available for sulphide oxidation and hence increases the risk of acid rock drainage unless the rock contains enough natural buffering capacity to neutralize the pH. In December, 2001, the New Brunswick Department of Transportation (NBOT) sponsored a field trial of geophysical surveying in order to assess its suitability as a screening tool for locating near-surface sulphides along proposed highway alignments. The goal was to develop a protocol that would allow existing programs of drilling and geochemical testing to be targeted more effectively, and provide design engineers with the information needed to reduce rock cuts where necessary and dispose of blasted material in a responsible fashion. Induced polarization (IP) was chosen as the primary geophysical method given its ability to detect low-grade disseminated mineralization. The survey was conducted in dipole-dipole mode using an exploration-style time domain IP system, dipoles 8 to 25 m in length, and six potential dipoles for each current dipole location (i.e. n = 1 - 6). Supplementary information was provided by resistivity and VLF-EM surveys sensitive to lateral changes in electrical conductivity, and by magnetic field surveying chosen for its sensitivity to the magnetic susceptibility of pyrrhotite. Geological and geochemical analyses of samples taken from several IP anomalies located along 4.3 line-km of proposed highway confirmed the effectiveness of the screening technique. IP pseudosections from a region of metamorphosed shales and volcaniclastic rocks identified discrete, well-defined mineralized zones. Stronger, overlapping, and more laterally extensive IP anomalies were observed over a section of graphitic and sulphide-bearing metasedimentary rocks. Attempts to use spectral IP characteristics to determine relative abundances of sulphides and graphite were not conclusive. The overall effectiveness of the screening technique however encouraged NBDOT to apply it to an additional 50 km of planned rock cuts along the corridor selected for the new Trans-Canada Highway.

Butler, K. E.; Al, T.; Bishop, T.

2004-05-01

150

Spin-polarized current induced in a single ferromagnetic strip due to inhomogeneous spin injection  

E-print Network

Spin-polarized current induced in a single ferromagnetic strip due to inhomogeneous spin injection that the inhomogeneous spin accumulation in a nonmagnetic layer induces the spin-polarized current flowing in a detector, the induced spin-polarized current causes the spin-valve-like signal in the Ni-Fe wire without any boundary

Otani, Yoshichika

151

Mask induced polarization effects at high NA Andrew Estroff, Yongfa Fan, Anatoly Bourov, Bruce Smith  

E-print Network

Mask induced polarization effects at high NA Andrew Estroff, Yongfa Fan, Anatoly Bourov, Bruce, material thickness, and illumination scheme all influence mask induced polarization effects. Keywords field of the TE polarized light induces a current in the length of the wires. Forward transmitted

Zanibbi, Richard

152

Measurements of submillimeter polarization induced by oblique reflection from aluminum alloy  

E-print Network

Measurements of submillimeter polarization induced by oblique reflection from aluminum alloy Tom Renbarger, Jessie L. Dotson, and Giles Novak We have measured the linear polarization induced in a beam of incidence in the range 15°­45°, we measured induced polarizations in the range 0.05%­0.25%. Our measurements

Novak, Giles

153

Microtubule-Induced Pins/Gai Cortical Polarity in Drosophila Neuroblasts  

E-print Network

Microtubule-Induced Pins/Gai Cortical Polarity in Drosophila Neuroblasts Sarah E. Siegrist1.09.043 SUMMARY Cortical polarity regulates cell division, mi- gration, and differentiation. Microtubules induce and Dlg/Pins co- immunoprecipitate, suggesting that micro- tubules induce Pins/Gai cortical polarity

Doe, Chris

154

Enhancement of induced V polarization due to rough interfaces in polycrystalline V/Fe/V trilayers  

E-print Network

Enhancement of induced V polarization due to rough interfaces in polycrystalline V/Fe/V trilayers C July 2009 The effect of interface roughness on the induced polarization of V in polycrystalline V-mean-square interfacial roughness at the Fe/V interfaces. The induced polarization found in V was constrained to the Fe

Haskel, Daniel

155

Polarization-induced distortion in stimulated Brillouin scattering slow-light systems  

E-print Network

Polarization-induced distortion in stimulated Brillouin scattering slow-light systems Avi Zadok,1 show that SBS-related polarization-induced distor- tion is yet another mechanism responsible for pulse. Thus, it is shown below that this SBS- related polarization induced distortion is analogous

Zadok, Avinoam

156

3D induced-polarization data inversion for complex resistivity Michael Commer1  

E-print Network

3D induced-polarization data inversion for complex resistivity Michael Commer1 , Gregory A. Newman1, the routine three-dimensional (3D) interpretation of voluminous induced polarization (IP) data sets still findings about the IP effects due to subsurface microbial activity. INTRODUCTION The induced-polarization

Hubbard, Susan

157

3DEMIII Workshop, February 2003, Adelaide. 1 3-D inversion of magnetic induced polarization data  

E-print Network

3DEMIII Workshop, February 2003, Adelaide. 1 3-D inversion of magnetic induced polarization data@geop.ubc.ca doug@geop.ubc.ca INTRODUCTION The magnetic induced polarization (MIP) is used as an alternative method to derive information relating to the induced polarization characteristics of the subsurface through

Oldenburg, Douglas W.

158

Light-induced spin polarizations in quantum rings  

NASA Astrophysics Data System (ADS)

Nonresonant circularly polarized electromagnetic radiation can exert torques on magnetizations by the inverse Faraday effect (IFE). Here, we discuss the enhancement of IFE by spin-orbit interactions. We illustrate the principle by studying a simple generic model system, i.e., the quasi-one-dimensional ring in the presence of linear/cubic Rashba and Dresselhaus interactions. We combine the classical IFE in electron plasmas that is known to cause persistent currents in the plane perpendicular to the direction of the propagation of light with the concept of current and spin-orbit-induced spin transfer torques. We calculate light-induced spin polarization that in ferromagnets might give rise to magnetization switching.

Joibari, Fateme K.; Blanter, Ya. M.; Bauer, Gerrit E. W.

2014-10-01

159

Topographic effects in resistivity and induced-polarization surveys  

Microsoft Academic Search

We have made a systematic study of dipole-dipole apparent resistivity anomalies due to topography and of the effect of irregular terrain on induced-polarization (IP) anomalies, using a two-dimensional (2-D), finite-element computer program. A valley produces a central apparent resistivity low in the resistivity pseudosection, flanked by zones of higher apparent resistivity. A ridge produces just the opposite anomaly pattern -

Richard C. Fox; G. W. Hohmann; T. J. Killpack; L. Rijo

1980-01-01

160

Ion-induced nucleation in polar one-component fluids  

E-print Network

We present a Ginzburg-Landau theory of ion-induced nucleation in a gas phase of polar one-component fluids, where a liquid droplet grows with an ion at its center. By calculating the density profile around an ion, we show that the solvation free energy is larger in gas than in liquid at the same temperature on the coexistence curve. This difference much reduces the nucleation barrier in a metastable gas.

Hikaru Kitamura; Akira Onuki

2005-08-01

161

Chemical Reaction-Induced Multi-molecular Polarization (CRIMP).  

PubMed

Here we present a novel hyperpolarization method, Chemical Reaction-Induced Multi-molecular Polarization (CRIMP), which could be applied to the study of several in vivo processes simultaneously including glycolysis, TCA cycle, fatty acid synthesis and pH mapping. Through the use of non-enzymatic decarboxylation, we generate four hyperpolarized imaging agents from hyperpolarized 1,2-(13)C pyruvic acid. PMID:25224323

Lee, Y; Zacharias, N M; Piwnica-Worms, D; Bhattacharya, P K

2014-10-01

162

Induced energy polarization of the vacuum and the resulting cosmology  

E-print Network

The theory of an induced energy polarized vacuum provides an alternative to the standard cosmological model. The theory has previously been shown to lead to the Baryonic Tully-Fisher Relationship [1], to agree with the observed rotation curve of the Galaxy [2], to readily produce the observed features in the rotational curves of other spiral galaxies [3], and to agree with observations of the Coma cluster [4]. All without the need for any free parameters. The theory of an induced energy polarized vacuum is now applied to superclusters. From a model of the distribution of superclusters, the overall density parameter of universe as given by the theory of an induced energy polarized vacuum is Omega = 0.94 plus/minus 0.23. This is consistent with a geometrically flat universe. In addition, by treating the superclusters as unbound systems, the theory leads to an accelerating expansion of the universe in line with observations and without requiring the need for dark energy.

Penner, Albert Raymond

2014-01-01

163

Induced polarization of {\\Lambda}(1116) in kaon electroproduction  

E-print Network

We have measured the induced polarization of the ${\\Lambda}(1116)$ in the reaction $ep\\rightarrow e'K^+{\\Lambda}$, detecting the scattered $e'$ and $K^+$ in the final state along with the proton from the decay $\\Lambda\\rightarrow p\\pi^-$.The present study used the CEBAF Large Acceptance Spectrometer (CLAS), which allowed for a large kinematic acceptance in invariant energy $W$ ($1.6\\leq W \\leq 2.7$ GeV) and covered the full range of the kaon production angle at an average momentum transfer $Q^2=1.90$ GeV$^2$.In this experiment a 5.50 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. We have mapped out the $W$ and kaon production angle dependencies of the induced polarization and found striking differences from photoproduction data over most of the kinematic range studied. However, we also found that the induced polarization is essentially $Q^2$ independent in our kinematic domain, suggesting that somewhere below the $Q^2$ covered here there must be a strong $Q^2$ dependence. Along wit...

Gabrielyan, M; Carman, D S; Park, K; Adhikari, K P; Adikaram, D; Amaryan, M J; Pereira, S Anefalos; Avakian, H; Ball, J; Baltzell, N A; Battaglieri, M; Baturin, V; Bedlinskiy, I; Biselli, A S; Bono, J; Boiarinov, S; Briscoe, W J; Brooks, W K; Burkert, V D; Cao, T; Celentano, A; Chandavar, S; Charles, G; Cole, P L; Contalbrigo, M; Cortes, O; Crede, V; DAngelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Doughty, D; Dupre, R; Fassi, L El; Eugenio, P; Fedotov, G; Fegan, S; Fleming, J A; Forest, T A; Garillon, B; Gevorgyan, N; Ghandilyan, Y; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Golovatch, E; Gothe, R W; Griffioen, K A; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hattawy, M; Hicks, K; Ho, D; Holtrop, M; Hughes, S M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Jenkins, D; Jiang, H; Jo, H S; Joo, K; Keller, D; Khandaker, M; Kim, W; Klein, F J; Koirala, S; Kubarovsky, V; Kuhn, S E; Kuleshov, S V; Lenisa, P; Levine, W I; Livingston, K; MacGregor, I J D; Mayer, M; McKinnon, B; Meyer, C A; Mestayer, M D; Mirazita, M; Mokeev, V; Moody, C I; Moutarde, H; Movsisyan, A; Munevar, E; Camacho, C Munoz; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Osipenko, M; Pappalardo, L L; Paremuzyan, R; Pasyuk, E; Peng, P; Phelps, W; Phillips, J J; Pisano, S; Pogorelko, O; Pozdniakov, S; Price, J W; Procureur, S; Protopopescu, D; Rimal, D; Ripani, M; Rizzo, A; Sabatie, F; Salgado, C; Schott, D; Schumacher, R A; Simonyan, A; Smith, G D; Sober, D I; Sokhan, D; Stepanyan, S S; Stepanyan, S; Strakovsky, I I; Strauch, S; Sytnik, V; Tang, W; Ungaro, M; Vlassov, A V; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Wei, X; Weinstein, L B; Zachariou, N; Zana, L; Zhang, J

2014-01-01

164

Induced energy polarization of the vacuum and the resulting cosmology  

E-print Network

The theory of an induced energy polarized vacuum provides an alternative to the standard cosmological model. The theory has previously been shown to lead to the Baryonic Tully-Fisher Relationship [1], to agree with the observed rotation curve of the Galaxy [2], to readily produce the observed features in the rotational curves of other spiral galaxies [3], and to agree with observations of the Coma cluster [4]. All without the need for any free parameters. The theory of an induced energy polarized vacuum is now applied to superclusters. From a model of the distribution of superclusters, the overall density parameter of universe as given by the theory of an induced energy polarized vacuum is Omega = 0.94 plus/minus 0.23. This is consistent with a geometrically flat universe. In addition, by treating the superclusters as unbound systems, the theory leads to an accelerating expansion of the universe in line with observations and without requiring the need for dark energy.

Albert Raymond Penner

2014-04-10

165

Magnetization-induced second harmonic generation in a polar ferromagnet.  

PubMed

Second harmonic generation (SHG) induced by spontaneous magnetization has been investigated for a polar ferromagnetic crystal of GaFeO3. The Kerr rotation of the second harmonic light becomes gigantic with decreasing temperature below the magnetic transition temperature (approximately =205 K), e.g., as large as 73 degrees at 100 K. The magnetic domains can be visualized by using that large nonlinear Kerr rotation. The spectrum of the magnetization-induced SHG as measured indicates the two-photon resonant electronic process on a Fe3+ ion in the crystal. PMID:14995401

Ogawa, Y; Kaneko, Y; He, J P; Yu, X Z; Arima, T; Tokura, Y

2004-01-30

166

Magnetization-Induced Second Harmonic Generation in a Polar Ferromagnet  

NASA Astrophysics Data System (ADS)

Second harmonic generation (SHG) induced by spontaneous magnetization has been investigated for a polar ferromagnetic crystal of GaFeO3. The Kerr rotation of the second harmonic light becomes gigantic with decreasing temperature below the magnetic transition temperature (?205 K), e.g., as large as 73° at 100K. The magnetic domains can be visualized by using that large nonlinear Kerr rotation. The spectrum of the magnetization-induced SHG as measured indicates the two-photon resonant electronic process on a Fe3+ ion in the crystal.

Ogawa, Y.; Kaneko, Y.; He, J. P.; Yu, X. Z.; Arima, T.; Tokura, Y.

2004-01-01

167

Disk instability and the spectral evolution of the 1992 outburst of the intermediate polar GK Persei  

NASA Technical Reports Server (NTRS)

The disk instability model can explain the previous history of dwarf-nova-like outbursts in the intermediate polar GK Per, which occur about once every three years. Disk models that reproduce the recurrence time and outburst light curves suggest that GK Per has a large effective inner disk radius (approx. 30-40 white dwarf radii) truncated by a strong magnetic field (10(exp 7) G). In this context, the effective radius is that of the portion of the disk that participates in the disk thermal instability. The radius derived is larger than the corotation radius, which must be an upper limit on the true dynamical inner radius of the disk. Disk instability models with this large effective inner radius predict that the ultraviolet continuum should be rather flat. Here we compare the predictions of the disk instability model to IUE observations of the 1981 outburst and to IUE and ROSAT observations of the recent 1992 outburst of GK Per. The model disk continuum spectral evolution is consistent with the observed UV and optical spectra, especially at maximum and in the early decay phase of the outburst. The consistency of the model with the observed UV spectra suggests that the effective inner radius of the disk is almost constant, independent of mass accretion rate, and that whatever structure lies between the effective inner radius and the corotation radius neither participates in the disk instability nor radiates substantially in the UV. The related physics of the inner disk region will be briefly discussed.

Kim, S.-W.; Wheeler, J. C.; Bruhweiler, F. C.; Fitzurka, M.; Beuermann, K.; Reinsch, K.; Mineshige, S.

1994-01-01

168

Current-induced spin polarization on metal surfaces probed by spin-polarized positron beam  

NASA Astrophysics Data System (ADS)

Current-induced spin polarization (CISP) on the outermost surfaces of Au, Cu, Pt, Pd, Ta, and W nanoscaled films were studied using a spin-polarized positron beam. The Au and Cu surfaces showed no significant CISP. In contrast, the Pt, Pd, Ta, and W films exhibited large CISP (3~15% per input charge current of 105 A/cm2) and the CISP of Ta and W were opposite to those of Pt and Pd. The sign of the CISP obeys the same rule in spin Hall effect suggesting that the spin-orbit coupling is mainly responsible for the CISP. The magnitude of the CISP is explained by the Rashba-Edelstein mechanism rather than the diffusive spin Hall effect. This settles a controversy, that which of these two mechanisms dominates the large CISP on metal surfaces.

Zhang, H. J.; Yamamoto, S.; Fukaya, Y.; Maekawa, M.; Li, H.; Kawasuso, A.; Seki, T.; Saitoh, E.; Takanashi, K.

2014-04-01

169

Para-hydrogen induced polarization in heterogeneous hydrogenationreactions  

SciTech Connect

We demonstrate the creation and observation ofpara-hydrogen-induced polarization in heterogeneous hydrogenationreactions. Wilkinson's catalyst, RhCl(PPh3)3, supported on eithermodified silica gel or a polymer, is shown to hydrogenate styrene intoethylbenzene and to produce enhanced spin polarizations, observed throughNMR, when the reaction was performed with H2 gas enriched in the paraspinisomer. Furthermore, gaseous phase para-hydrogenation of propylene topropane with two catalysts, the Wilkinson's catalyst supported onmodified silica gel and Rh(cod)(sulfos) (cod = cycloocta-1,5-diene;sulfos) - O3S(C6H4)CH2C(CH2PPh2)3) supported on silica gel, demonstratesheterogeneous catalytic conversion resulting in large spin polarizations.These experiments serve as a direct verification of the mechanism ofheterogeneous hydrogenation reactions involving immobilized metalcomplexes and can be potentially developed into a practical tool forproducing catalyst-free fluids with highly polarized nuclear spins for abroad range of hyperpolarized NMR and MRI applications.

Koptyug, Igor V.; Kovtunov, Kirill; Burt, Scott R.; Anwar, M.Sabieh; Hilty, Christian; Han, Song-I; Pines, Alexander; Sagdeev, Renad Z.

2007-01-31

170

Induced polarization of ?(1116) in kaon electroproduction with CLAS  

NASA Astrophysics Data System (ADS)

The CLAS Collaboration is using the p(e,e'K+p)?- reaction to perform a measurement of the induced polarization of the electroproduced ?(1116). The parity-violating weak decay of the ? into p&pgr- (64%) allows extraction of the recoil polarization of the ?. This study uses the CEBAF Large Acceptance Spectrometer (CLAS) to detect the scattered electron, the kaon, and the decay proton. CLAS allows for a large kinematic acceptance with 0.8 <= Q2 <= 3.5 GeV2, 1.6 <= W <= 3.0 GeV, as well as the kaon scattering angle. In this experiment a 5.5 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The goal is to map out the kinematic dependencies for this polarization observable to provide new constraints for theoretical models of the electromagnetic production of kaon-hyperon final states. Along with previously published photo- and electro-production cross sections and polarization observables from CLAS, SAPHIR, and GRAAL, these data are needed in a coupled-channel analysis to identify previously unobserved s-channel resonances.

Gabrielyan, Marianna; Raue, Brian; Carman, Daniel S.; Park, Kijun

2013-10-01

171

Measurement of energy contrast of amplified ultrashort pulses using cross-polarized wave generation and spectral interferometry.  

PubMed

We present a method using spectral interferometry (SI) to characterize a pulse in the presence of an incoherent background such as amplified spontaneous emission (ASE). The output of a regenerative amplifier is interfered with a copy of the pulse that has been converted using third-order cross-polarized wave generation (XPW). The ASE shows as a pedestal background in the interference pattern. The energy contrast between the short-pulse component and the ASE is retrieved. The spectra of the interacting beams are obtained through an improvement to the self-referenced spectral interferometry (SRSI) analysis. PMID:25089416

Iliev, Marin; Meier, Amanda K; Galloway, Benjamin; Adams, Daniel E; Squier, Jeff A; Durfee, Charles G

2014-07-28

172

Polarization Changes in Optical Fibers induced by SelfPhase Modulation and CrossPhase  

E-print Network

Polarization Changes in Optical Fibers induced by Self­Phase Modulation and Cross­Phase Modulation in Conjunction with Birefrigence Lutz Rapp July 20, 2008 Abstract-- Polarization dependence of various fiber field of research activities. Polarization­ mode dispersion (PMD) and polarization­dependent loss (PDL

Paris-Sud XI, Université de

173

L E T T E R S Microtubules induce self-organization of polarized PAR  

E-print Network

L E T T E R S Microtubules induce self-organization of polarized PAR domains in Caenorhabditis and Geraldine Seydoux1,2 A hallmark of polarized cells is the segregation of the PAR polarity regulators, atypical protein kinase C (aPKC) and PAR-1, have been implicated in polarity maintenance1

Seydoux, Geraldine

174

Electro-optic birefringence induced polarization anisotropy in vertical-cavity semiconductor optical amplifiers  

E-print Network

Electro-optic birefringence induced polarization anisotropy in vertical-cavity semiconductor-0407 pwen@ece.ucsd.edu Abstract: The polarization anisotropy including polarization dependent gain (PDG) and frequency splitting in VCSOAs are measured. Measurements of the output polarization state show

Esener, Sadik C.

175

Reorientation-induced spectral diffusion in vibrational sum-frequency-generation spectroscopy.  

PubMed

There is a growing appreciation that dynamic processes play an important role in determining the line shape in surface-selective, nonlinear spectroscopies such as vibrational sum-frequency-generation (VSFG). Here we analyze the influence that reorientation can have on VSFG spectra when the vibrational transition frequency is a function of orientation. Under these circumstances, reorientation-induced spectral diffusion (RISD) causes the underlying spectral line shape to become time dependent. Unlike previously reported mechanisms through which reorientation can contribute to the VSFG signal, RISD influences the line shape regardless of the degree of polarization of the Raman transition that is probed. We assess the impact of RISD on VSFG spectra using a model system of liquid acetonitrile at a silica interface. Comparison of delay-time-dependent VSFG spectra with simulations that employ static line shapes suggests that RISD contributes substantially to the spectra, particularly at delay times that are comparable to or greater than the probe pulse duration. The observed behavior is in qualitative agreement with a two-state RISD model that uses orientational distributions determined from previous molecular dynamics simulations. PMID:24088038

Rivera, Christopher A; Souna, Amanda J; Bender, John S; Manfred, Katherine; Fourkas, John T

2013-12-12

176

Spectral binning for mitigation of polarization mode dispersion artifacts in catheter-based optical frequency domain imaging.  

PubMed

Polarization mode dispersion (PMD) has been recognized as a significant barrier to sensitive and reproducible birefringence measurements with fiber-based, polarization-sensitive optical coherence tomography systems. Here, we present a signal processing strategy that reconstructs the local retardation robustly in the presence of system PMD. The algorithm uses a spectral binning approach to limit the detrimental impact of system PMD and benefits from the final averaging of the PMD-corrected retardation vectors of the spectral bins. The algorithm was validated with numerical simulations and experimental measurements of a rubber phantom. When applied to the imaging of human cadaveric coronary arteries, the algorithm was found to yield a substantial improvement in the reconstructed birefringence maps. PMID:23938487

Villiger, Martin; Zhang, Ellen Ziyi; Nadkarni, Seemantini K; Oh, Wang-Yuhl; Vakoc, Benjamin J; Bouma, Brett E

2013-07-15

177

Field-resolved measurement of reaction-induced spectral densities by polarizability response spectroscopy  

NASA Astrophysics Data System (ADS)

The experimental design and theoretical description of a novel five-pulse laser spectroscopy is presented with an application to a pyridinium charge transfer complex in acetonitrile and methanol. In field-resolved polarizability response spectroscopy (PORS), an electronically resonant laser pulse first excites a solvated chromophore (reactant) and off-resonant Raman spectra of the resulting nuclear motions are measured as a function of the reaction time. The present apparatus differs from our earlier design by performing the Raman probe measurement (with fixed pulse delays) in the frequency domain. In addition, the full electric fields of the signals are measured by spectral interferometry to separate nonresonant and Raman responses. Our theoretical model shows how the PORS signal arises from nuclear motions that are displaced/driven by the photoinduced reaction. The field-resolved off-resonant (of the solute's electronic transitions) probing favors detection of solvent (as opposed to solute) dynamics coupled to the reaction. The sign of the signal represents the relative strengths of polarization responses associated with the ground and photoexcited solutions. Signatures of nonresonant and PORS signal contributions to the experimental results are analyzed with numerical calculations based on a theoretical model we have developed for reaction-induced PORS. Our model identifies two mechanisms of PORS signal generation: (i) structural relaxation induced resonance; (ii) dephasing induced resonance. In the charge transfer reaction investigated, the solvent-dependent and time-evolving (solvent) polarizability spectral density (PSD) is readily obtained. The general trend of an initial broadband inertial nuclear response followed by a decrease in the linewidth of the PSD establishes that the measured PSD is inconsistent with the approximation of a linear response. Furthermore, the explicit time evolution of the PSD is important for properly describing solvent control of reactions that do not satisfy the time-scale separability inherent to nonadiabatic kinetic models.

Moran, Andrew M.; Nome, Rene A.; Scherer, Norbert F.

2007-11-01

178

Mask induced polarization Andrew Estroff, Yongfa Fan, Anatoly Bourov, Frank Cropanese,  

E-print Network

Mask induced polarization Andrew Estroff, Yongfa Fan, Anatoly Bourov, Frank Cropanese, Neal, Rochester, NY 14623 ABSTRACT The objective of this paper is to study the polarization induced by mask with mask features. RCWA allows the dependence of polarization effects of various wavelengths of radiation

Zanibbi, Richard

179

SHEAR FLOW INDUCED POLARIZATION IN FERROELECTRIC SMECTICS C P. PIERANSKI, E. GUYON and P. KELLER (*)  

E-print Network

1005 SHEAR FLOW INDUCED POLARIZATION IN FERROELECTRIC SMECTICS C P. PIERANSKI, E. GUYON and P to the plane of tilt (see Fig. 1). This, in turn, can induce a spontaneous polarization P in each layer smectic C phase has been established from polarization measurements in the presence of an electric field

Boyer, Edmond

180

STRONG POLARIZATION OF THE RESIDUAL NUCLEUS IN A HEAVY-ION INDUCED TRANSFER REACTION  

E-print Network

STRONG POLARIZATION OF THE RESIDUAL NUCLEUS IN A HEAVY-ION INDUCED TRANSFER REACTION F. POUGHEON, P in a heavy-ion induced transfer. Polarization phenomena in heavy-ion reactions have already been studied de reproduire la polarisation correspondante. Abstract. 2014 A strong polarization of 20Ne levels has

Paris-Sud XI, Université de

181

Modeling Robustness Tradeoffs in Yeast Cell Polarization Induced by Spatial Gradients  

E-print Network

Modeling Robustness Tradeoffs in Yeast Cell Polarization Induced by Spatial Gradients Ching-S, Nie Q, Yi T-M (2008) Modeling Robustness Tradeoffs in Yeast Cell Polarization Induced by Spatial Cells localize (polarize) internal components to specific locations in response to external signals

Nie, Qing

182

Imaging the anterior eye segment by polarization-sensitive spectral-domain and swept-source optical coherence tomography  

NASA Astrophysics Data System (ADS)

Polarization-sensitive optical coherence tomography (PS-OCT) has been developed to measure the birefringent properties of the human eye. In the retina, retinal nerve fiber layer and retinal pigment epitherial layer have the characteristic birefringent properties. 1.2 In addition to such normal tissue, abnormal fibrous tissue of the retina can be detected by PS-OCT. 3 In the anterior segment, the cornea is a birefringent tissue due to the multi-layered fibril structure. 4 The sclera and tendon also have the birefringence and the contrast of these structures can be enhanced by PS-OCT. 5 These studies have been used time-domain or spectral-domain PS-OCT. Recently, swept-source OCT (SS-OCT) has been applied for anterior eye segment imaging. 6 At the 1.3 um wavelength, SS-OCT is more promising than spectral-domain OCT, because the available camera for the spectrometer is limited. Three-dimensional imaging of the anterior segment is possible owing to the high penetration, high acquisition speed and high sensitivity. We have developed a new system of SS-OCT with polarization sensitivity. In this study, we measure the birefringent properties of anterior eye segment by polarization-sensitive spectral-domain OCT (PS-SD-OCT) at 840 nm and polarizationsensitive swept-source OCT (PS-SS-OCT) at 1.3 um, and evaluated the possibilities for clinical application.

Miura, Masahiro; Yamanari, Masahiro; Yatagai, Toyohiko; Yasuno, Yoshiaki

2008-02-01

183

Polarization and incidence insensitive dielectric electromagnetically induced transparency metamaterial.  

PubMed

In this manuscript, we demonstrate numerically classical analogy of electromagnetically induced transparency (EIT) with a windmill type metamaterial consisting of two dumbbell dielectric resonator. With proper external excitation, dielectric resonators serve as EIT bright and dark elements via electric and magnetic Mie resonances, respectively. Rigorous numerical analyses reveal that dielectric metamaterial exhibits sharp transparency peak characterized by large group index due to the destructive interference between EIT bright and dark resonators. Furthermore, such EIT transmission behavior keeps stable property with respect to polarization and incidence angles. PMID:24105514

Zhang, Fuli; Zhao, Qian; Zhou, Ji; Wang, Shengxiang

2013-08-26

184

POLARIZED RAMAN SPECTROSCOPIC STUDY OF THE PRESSURE-INDUCED PHASE CHANGE FROM  

E-print Network

1747P POLARIZED RAMAN SPECTROSCOPIC STUDY OF THE PRESSURE-INDUCED PHASE CHANGE FROM C2/C TO P21/C will be reported. Polarized spectra of an oriented crystal will be presented demonstrating the ability to obtain

Downs, Robert T.

185

The Spectral Properties of (-)-Epigallocatechin 3-O-Gallate (EGCG) Fluorescence in Different Solvents: Dependence on Solvent Polarity  

PubMed Central

(-)-Epigallocatechin 3-O-gallate (EGCG) a molecule found in green tea and known for a plethora of bioactive properties is an inhibitor of heat shock protein 90 (HSP90), a protein of interest as a target for cancer and neuroprotection. Determination of the spectral properties of EGCG fluorescence in environments similar to those of binding sites found in proteins provides an important tool to directly study protein-EGCG interactions. The goal of this study is to examine the spectral properties of EGCG fluorescence in an aqueous buffer (AB) at pH=7.0, acetonitrile (AN) (a polar aprotic solvent), dimethylsulfoxide (DMSO) (a polar aprotic solvent), and ethanol (EtOH) (a polar protic solvent). We demonstrate that EGCG is a highly fluorescent molecule when excited at approximately 275 nm with emission maxima between 350 and 400 nm depending on solvent. Another smaller excitation peak was found when EGCG is excited at approximately 235 nm with maximum emission between 340 and 400 nm. We found that the fluorescence intensity (FI) of EGCG in AB at pH=7.0 is significantly quenched, and that it is about 85 times higher in an aprotic solvent DMSO. The Stokes shifts of EGCG fluorescence were determined by solvent polarity. In addition, while the emission maxima of EGCG fluorescence in AB, DMSO, and EtOH follow the Lippert-Mataga equation, its fluorescence in AN points to non-specific solvent effects on EGCG fluorescence. We conclude that significant solvent-dependent changes in both fluorescence intensity and fluorescence emission shifts can be effectively used to distinguish EGCG in aqueous solutions from EGCG in environments of different polarity, and, thus, can be used to study specific EGCG binding to protein binding sites where the environment is often different from aqueous in terms of polarity. PMID:24278192

Snitsarev, Vladislav; Young, Michael N.; Miller, Ross M. S.; Rotella, David P.

2013-01-01

186

[The multi-angle polarization spectral character of water and its applications in water color remote sensing].  

PubMed

The reflectance of pure water is very low at visible and near infrared bands. Its spectral characteristics are not obvious. Water always shows dark hue in optical remote sensing images. This dark hue causes the difficulties in water remote sensing identification. There is an interesting phenomenon when the authors research the water polarization spectroscopy. The authors measured water's polarization spectra and reflectance spectra at different view zenith angles using the ASD spectrometer. When the view zenith angle was zero (measured vertically), as the spectrum people commonly measure, there was no polarization phenomenon at the water surface, and the reflectance was low at each band. Along with the increase in view zenith angle, the DOP spectra curves increased evidently, while the reflectance curves only changed a little. When the view zenith angle was over 30 degree, the values of DOP spectrum were much larger than the reflectance spectrum values at the entire visible and near infrared bands. At some bands, the DOP value was several dozen times than its reflectance value. This phenomenon shows that the water's brightness in DOP image is much higher than its brightness in intensity image under the same condition. This rule was verified by the PARASOL multiangle polarization satellite data. Comparing the average brightness of DOP images with the average brightness of intensity images at 490, 670 and 865 nm band, the former is higher than the latter apparently. The brighter DOP images are better for water remote sensing identification It is the first time that the authors found this special multiangle polarization spectral character of water. It revealed the advantage of water detection using the multiangle polarization remote sensing data. This method solved the low reflectivity problem of water color remote sensing. It will greatly improve the capability of water remote sensing identification and the retrieval accuracy of water quality parameters. PMID:20384143

Wu, Tai-Xia; Yan, Lei; Xiang, Yun; Zhao, Yun-Sheng; Chen, Wei

2010-02-01

187

Black hole stereotyping: Induced gravito-static polarization  

E-print Network

We discuss the black hole effective action and define its static subsector. We determine the induced gravito-static polarization constants (electric Love numbers) of static black holes (Schwarzschild) in an arbitrary dimension, namely the induced mass multipole as a result of an external gravitational field. We demonstrate that in 4d these constants vanish thereby settling a disagreement in the literature. Yet in higher dimensions these constants are non-vanishing, thereby disproving (at least in d>4) speculations that black holes have no effective couplings beyond the point particle action. In particular, when l/(d-3) is half integral these constants demonstrate a (classical) renormalization flow consistent with the divergences of the effective field theory. In some other cases the constants are negative indicating a novel non-spherical instability. The theory of hypergeometric functions plays a central role.

Barak Kol; Michael Smolkin

2011-10-17

188

Black hole stereotyping: Induced gravito-static polarization  

E-print Network

We discuss the black hole effective action and define its static subsector. We determine the induced gravito-static polarization constants (electric Love numbers) of static black holes (Schwarzschild) in an arbitrary dimension, namely the induced mass multipole as a result of an external gravitational field. We demonstrate that in 4d these constants vanish thereby settling a disagreement in the literature. Yet in higher dimensions these constants are non-vanishing, thereby disproving (at least in d>4) speculations that black holes have no effective couplings beyond the point particle action. In particular, when l/(d-3) is half integral these constants demonstrate a (classical) renormalization flow consistent with the divergences of the effective field theory. In some other cases the constants are negative indicating a novel non-spherical instability. The theory of hypergeometric functions plays a central role.

Kol, Barak

2011-01-01

189

Gravitational Wave Induced Large-scale Polarization of \\\\Cosmic Microwave Background Radiation  

E-print Network

We discuss the contribution of gravitational wave to the cosmic microwave background radiation (CMBR) anisotropy and polarization. It is found that the large-scale polarization of CMBR is less than 1\\% for a standard recombination universe. The effect of matter reionization will enhance the CMBR polarization to a 10\\% level. We have computed the CMBR polarization for two extreme cases (not absolutely ruled out) and found that further enhancement of the ratio is possible. We conclude that measuring the polarization of CMBR on large-angular scales can probe the ionization history of the early universe, set constraints on baryon density and the spectral index of the gravitational waves.

Ka Lok Ng; Kin-Wang Ng

1994-06-30

190

N-polar III-nitride quantum well light-emitting diodes with polarization-induced doping  

SciTech Connect

Nitrogen-polar III-nitride heterostructures present unexplored advantages over Ga(metal)-polar crystals for optoelectronic devices. This work reports N-polar III-nitride quantum-well ultraviolet light-emitting diodes grown by plasma-assisted molecular beam epitaxy that integrate polarization-induced p-type doping by compositional grading from GaN to AlGaN along N-face. The graded AlGaN layer simultaneously acts as an electron blocking layer while facilitating smooth injection of holes into the active region, while the built-in electric field in the barriers improves carrier injection into quantum wells. The enhanced doping, carrier injection, and light extraction indicate that N-polar structures have the potential to exceed the performance of metal-polar ultraviolet light-emitting diodes.

Verma, Jai; Simon, John; Protasenko, Vladimir; Kosel, Thomas; Xing, Huili Grace; Jena, Debdeep [Department of Electrical Engineering, University of Notre Dame, Indiana 46556 (United States)

2011-10-24

191

Localization of spectral receptors in the ommatidium of butterfly compound eye determined by polarization sensitivity  

Microsoft Academic Search

1.A butterfly Papilio has 5 types of spectral receptors in the compound eye. The spectral sensitivity of each type peaks in the UV, violet, blue, green, and red wavelengths, respectively. The green type contains two subtypes with and without a UV secondary peak. Here we studied the localization of these spectral receptors within the ommatidium.2.An ommatidium contains 9 photoreceptors (R1–9),

Kouichi Bandai; Kentaro Arikawa; Eisuke Eguchi

1992-01-01

192

Spectral and polarized light sensitivity of photoreceptors in the compound eye of the cricket ( Gryllus bimaculatus )  

Microsoft Academic Search

Retinula cells in the compound eye of the cricket (Gryllus bimaculatus) were recorded intracellularly and stained with Lucifer yellow. Two different methods were used to determine the spectral sensitivity of these cells: a) the spectral scanning method, and b) the conventional flash method. Three spectral types, with S(?)-curves close to the rhodopsin-absorption functions, were found with?max at 332 nm (UV),

F. Zufall; M. Schmitt; R. Menzel

1989-01-01

193

Electric Field-Induced Polarization of Charged Cell Surface Proteins Does Not  

E-print Network

Electric Field-Induced Polarization of Charged Cell Surface Proteins Does Not Determine or speed of motility. Thus, our results demonstrate that electric field-induced polarization of charged, Columbia University, New York, New York Galvanotaxis, that is, migration induced by DC electric fields

Tong, Liang

194

Ion-induced nucleation in polar one-component fluids Hikaru Kitamuraa  

E-print Network

Ion-induced nucleation in polar one-component fluids Hikaru Kitamuraa and Akira Onuki Department-Landau theory of ion-induced nucleation in polar one-component flu- ids in a gas phase. It will be based on our; published online 27 September 2005 We present a Ginzburg-Landau theory of ion-induced nucleation in a gas

195

Electromagnetic fields induced by a cuboidal inclusion with uniform spontaneous polarization and magnetization  

E-print Network

Electromagnetic fields induced by a cuboidal inclusion with uniform spontaneous polarization for the electromagnetic fields induced by a cuboidal inclusion with uniform spontaneous polarization and magnetization are employed to obtain the solution, with the results for the induced electric and magnetic potentials as well

Pan, Ernie

196

LINE-INTERLOCKING EFFECTS ON POLARIZATION IN SPECTRAL LINES BY RAYLEIGH AND RAMAN SCATTERING  

SciTech Connect

The polarized spectrum of the Sun and stars is formed from the scattering of anisotropic radiation on atoms. Interpretation of this spectrum requires the solution of polarized line transfer in multilevel atomic systems. While sophisticated quantum theories of polarized line formation in multilevel atomic systems exist, they are limited by the approximation of complete frequency redistribution in scattering. The partial frequency redistribution (PRD) in line scattering is a necessary component in modeling the polarized spectra of strong lines. The polarized PRD line scattering theories developed so far confine themselves to a two-level or a two-term atom model. In this paper, we present a heuristic approach to the problem of polarized line formation in multilevel atoms taking into account the effects of PRD and a weak magnetic field. Starting from the unpolarized PRD multilevel atom approach of Hubeny et al., we incorporate the polarization state of the radiation field. However, the lower level polarization is neglected. Two iterative methods of solving the polarized PRD line transfer in multilevel atoms are also presented. Taking the example of a five-level Ca II atom model, we present illustrative results for an isothermal one-dimensional model atmosphere.

Sampoorna, M.; Nagendra, K. N. [Indian Institute of Astrophysics, Koramangala, Bangalore 560 034 (India); Stenflo, J. O., E-mail: sampoorna@iiap.res.in, E-mail: knn@iiap.res.in, E-mail: stenflo@astro.phys.ethz.ch [Institute of Astronomy, ETH Zurich, CH-8093 Zurich (Switzerland)

2013-06-20

197

Current-induced remanent polarization of charge-density waves  

NASA Astrophysics Data System (ADS)

It is found by measuring the low-field conductivity of segments of TaS3 single crystals that a current pulse equal to or larger than threshold for sliding charge-density-wave (CDW) conduction permanently destroys the inversion symmetry of the sample. The segments are limited at one end by the usual silver paint contacts which strongly perturb the motion of CDW's while at the other end a special weakly perturbing contact is applied. The low-field resistance of the segments depends on whether the last sliding CDW current pulse enters or exists the strongly perturbing contact. The results are interpreted as a direct confirmation of current-induced remanent CDW polarization recently reported by Janossy, Mihaly, and Kriza.

Mihály, L.; Jánossy, A.

1984-09-01

198

Geometrically induced electric polarization in conical topological insulators  

E-print Network

We study the topological magnetoelectric effect on a conical topological insulator when a point charge $q$ is near the cone apex. The Hall current induced on the cone surface and the image charge configuration are determined. We also study a kind of gravitational Aharonov-Bohm effect in this geometry and realize a phase diference betwen the components of the wavefunctions (spinors) upon closed parallel transport around the (singular) cone tip. Concretely, a net current flowing towards cone apex (or botton) shows up, yielding electric polarization of the conical topological insulator. Such an effect may be detected, for instance, by means of the net accumulated Hall charge near the apex. Once it depends only on the geometry of the material (essetially, the cone apperture angle) this may be faced as a microscopic scale realization of (2+1)-dimensional Einstein gravity.

Jakson M. Fonseca; Winder A. Moura-Melo; Afranio R. Pereira

2011-11-29

199

Spectral features of lightning-induced ion cyclotron waves at low latitudes: DEMETER observations and simulation  

E-print Network

Spectral features of lightning-induced ion cyclotron waves at low latitudes: DEMETER observations to study proton whistlers, placing emphasis on low-latitude events originating from lightning strokes. Jiícek, F. Nmec, M. Parrot, O. Santolik, and E. E. Titova (2012), Spectral features of lightning

Santolik, Ondrej

200

Sudden Death of Entanglement induced by Polarization Mode Dispersion Cristian Antonelli,1  

E-print Network

Sudden Death of Entanglement induced by Polarization Mode Dispersion Cristian Antonelli,1 Mark study the decoherence of polarization-entangled photon pairs subject to the effects of polariza- tion mode dispersion, the chief polarization decoherence mechanism in optical fibers. We show that fiber

Fisher, Kathleen

201

Disorder-induced spin polarization in restricted geometries E. Eisenberg and R. Berkovits  

E-print Network

Disorder-induced spin polarization in restricted geometries E. Eisenberg and R. Berkovits disorder enhances the spin polarization of the system. The tendency of disorder to enhance magnetism in the ground state may be relevant to recent experimental observations of spin polarized ground states

Eisenberg, Eli

202

Satellite observations of polar mesospheric clouds by the solar backscattered ultraviolet spectral radiometer - Evidence of a solar cycle dependence  

NASA Technical Reports Server (NTRS)

Results are presented on eight years of satellite observations of the polar mesospheric clouds (PMCs) by the SBUV spectral radiometer, showing that PMCs occur in the summertime polar cap regions of both hemispheres and that they exhibit year-to-year variability. It was also found that the increase in the PMC occurrence frequency was inversely correlated with solar activity. Two kinds of hemispherical asymmetries could be identified: (1) PMCs in the Northern Hemisphere were significantly brighter than in the Southern Hemisphere, in accordance with previous results derived from SME data; and (2) the solar cycle response in the south is more pronounced than in the north. The paper also describes the cloud detection algorithm.

Thomas, Gary E.; Mcpeters, Richard D.; Jensen, Eric J.

1991-01-01

203

Development of a field-widened Michelson spectroscopic filter for a polarized near-infrared high spectral resolution lidar  

NASA Astrophysics Data System (ADS)

Standard backscatter lidars encounter problems when solving the two unknowns (aerosol backscatter coefficient and extinction coefficient) from the only one recorded lidar equation. With the help of the high-spectral-resolution filter, high spectral resolution lidars (HSRLs) can provide unambiguous retrieval without critical assumptions. Spectral discrimination between scattering from molecules and aerosols or cloud particles is the basis of the HSRL technique, and several lidar approaches have been developed to obtain this discrimination. Iodine cell filter, which is a kind of atomic/molecular absorption filter, is robust, stable, and can achieve very good separation of aerosol Mie scattering from atmosphere molecular Cabannes scattering. However, absorption filters are lossy and gaseous absorption lines do not exist at many convenient laser wavelengths. Fabry-Perot interferometers are simple and can be tuned to any wavelength, but are limited by acceptance angle. Field-widened Michelson interferometer (FWMI) is considered to have the ability to overcome the deficiencies of the aforementioned filters as it can perform well at relatively large off-axis angles, is nearly lossless, and can be built to any wavelength. In this paper, the development process of an FWMI that is introduced to be the spectroscopic filter for a polarized near-infrared HSRL instrument will be present. The retrieval process of the aerosol optical properties, the design requirements with special focus on the selection of the free spectral range (FSR) of the FWMI, as well as the design result will be described in detail.

Liu, Dong; Yang, Yongying; Cheng, Zhongtao; Ling, Tong; Huang, Hanlu; Zhou, Yudi; Zhang, Qiaoshuang; Zhang, Bo; Shen, Yibing

2013-09-01

204

Retrieval of aerosol optical properties over a vegetation surface using multi-angular, multi-spectral, and polarized data  

NASA Astrophysics Data System (ADS)

An algorithm to retrieve aerosol optical properties using multi-angular, multi-spectral, and polarized data without a priori knowledge of the land surface was developed. In the algorithm, the surface polarized reflectance was estimated by eliminating the atmospheric scattering from measured polarized reflectance at 1640 nm. A lookup table (LUT) and an iterative method were adopted in the algorithm to retrieve the aerosol optical thickness (AOT, at 665 nm) and the Ångström exponent (computed between the AOTs at 665 and 865 nm). Experiments were performed in Tianjin to verify the algorithm. Data were provided by a newly developed airborne instrument, the Advanced Atmosphere Multi-angle Polarization Radiometer (AMPR). The AMPR measurements over the target field agreed well with the nearby ground-based sun photometer. An algorithm based on Research Scanning Polarimeter (RSP) measurements was introduced to validate the observational measurements along a flight path over Tianjin. The retrievals were consistent between the two algorithms. The AMPR algorithm shows potential in retrieving aerosol optical properties over a vegetation surface.

Wang, Han; Sun, Xiaobing; Sun, Bin; Liang, Tianquan; Li, Cuili; Hong, Jin

2014-07-01

205

A fluctuation-induced plasma transport diagnostic based upon fast-Fourier transform spectral analysis  

NASA Technical Reports Server (NTRS)

A diagnostic, based on fast Fourier-transform spectral analysis techniques, that provides experimental insight into the relationship between the experimentally observable spectral characteristics of the fluctuations and the fluctuation-induced plasma transport is described. The model upon which the diagnostic technique is based and its experimental implementation is discussed. Some characteristic results obtained during the course of an experimental study of fluctuation-induced transport in the electric field dominated NASA Lewis bumpy torus plasma are presented.

Powers, E. J.; Kim, Y. C.; Hong, J. Y.; Roth, J. R.; Krawczonek, W. M.

1978-01-01

206

Light-induced scattering and energy transfer between orthogonally-polarized waves  

E-print Network

We present a detailed experimental investigation on polarization-isotropic and polarization-anisotropic holographic scattering in lithium niobate crystal doped with iron when recording parasitic gratings with an ordinary polarized pump beam. The kinetics of both types of scattering during the whole process of recording is studied. Holographic scattering is presented as a simple technique to monitor the energy transfer between beams of different polarization. Moreover, the spectral and the angular dependence of the transmitted intensity of the crystal during the reconstruction of the auto-generated parasitic gratings are measured.

M. A. Ellabban

2008-01-16

207

Optical feedback induces polarization mode hopping in vertical-cavity surface-emitting lasers  

Microsoft Academic Search

Vertical-cavity surface-emitting lasers subjected to weak polarization-insensitive optical feedback are studied experimentally and theoretically. We find that the feedback induces random anticorrelated hopping between the two orthogonal linearly polarized modes. This polarization mode hopping is accompanied by rapid anticorrelated oscillations in the linearly polarized intensities at the external-cavity frequency. The study of a simple stochastic delay differential equation suggests that

M. Sciamanna; K. Panajotov; H. Thienpont; I. Veretennicoff; P. Mégret; M. Blondel

2003-01-01

208

Evanescent imaging with induced polarization by using a solid immersion lens  

Microsoft Academic Search

Image contrast enhancement, high lateral resolution, and height information are obtained with induced polarization evanescent imaging using a solid immersion lens. Experiments are conducted by imaging features on a patterned Si substrate. Imaging theory is used to predict optimum orientation of high-spatial-frequency samples, and a topographical image is derived from the induced polarization image through a calibration procedure. A numerical

Tao Chen; Tom D. Milster; Seung-Hune Yang; Delbert Hansen

2007-01-01

209

Ion induced electronic excitations in a spin-polarized electron gas  

E-print Network

Ion induced electronic excitations in a spin-polarized electron gas M. Alducin a R. D#19;#16;ez Mui the stopping power of a H atom and the number of electrons it excites, when it moves slowly in a spin-polarized electron gas. The potential induced by the projectile in which the medium electrons scatter o#11

Muiño, Ricardo Díez

210

A Set of Analytical Formulae to Model Deglaciation-Induced Polar Wander  

E-print Network

A Set of Analytical Formulae to Model Deglaciation- Induced Polar Wander W. Keller Institute of Technology, Perth, Australia Abstract. Traditionally, deglaciation-induced po- lar wander changes the solution of convolution integrals. As being a central aspect of polar wander modelling we also revisit

Stuttgart, Universität

211

Dim-Red-Light-Induced Increase in Polar Auxin Transport in Cucumber Seedlings1  

E-print Network

Dim-Red-Light-Induced Increase in Polar Auxin Transport in Cucumber Seedlings1 I. Development and characterized a system to analyze light effects on auxin transport independent of photosynthetic effects. Polar transport. This light- induced change probably manifests itself by alteration of function of the auxin

Jones, Alan M.

212

ccsd00000796 Electric-eld induced capillary interaction of charged particles at a polar interface  

E-print Network

induced capillary interaction of charged particles at a polar interface. The algebraic tailsccsd­00000796 (version 1) : 28 Oct 2003 Electric-#12;eld induced capillary interaction of charged particles at a polar interface Lionel Foret and Alois Wurger CPMOH #3; , Universit#19;e Bordeaux 1, 351

213

Induced Nucleon Polarization and Meson-Exchange Currents in (e,e'p) Reactions  

E-print Network

Nucleon recoil polarization observables in $(e,e'\\vec{p})$ reactions are investigated using a semi-relativistic distorted-wave model which includes one- and two-body currents with relativistic corrections. Results for the induced polarization asymmetry are shown for closed-shell nuclei and a comparison with available experimental data for $^{12}$C is provided. A careful analysis of meson exchange currents shows that they may affect significantly the induced polarization for high missing momentum.

F. Kazemi Tabatabaei; J. E. Amaro; J. A. Caballero

2004-02-02

214

Polarized Parton Distribution in Neutrino Induced Heavy Flavor Production  

E-print Network

In order to examine polarized strange quark distribution, semi-inclusive $D/\\Dbar$ production in neutrino deep inelastic scattering is studied including ${\\cal O}(\\alpha_s)$ corrections. Cross section and spin asymmetry are calculated by using various parametrizations of polarized parton distribution functions. It is found that $\\Dbar$ production is promising to directly extract the polarized strange sea.

Kazutaka Sudoh

2002-12-05

215

Induced Growth of Asymmetric Nanocantilever Arrays on Polar Surfaces Z. L. Wang,1,* X.Y. Kong,1  

E-print Network

Induced Growth of Asymmetric Nanocantilever Arrays on Polar Surfaces Z. L. Wang,1,* X.Y. Kong,1 show that the surface polarity can induce asymmetric growth on the two opposite surfaces. Zinc oxide-terminated ZnO (0001) polar surface is chemically active and the oxygen- terminated 0001 polar surface is inert

Wang, Zhong L.

216

Effects of polarization on laser-induced electron-ion recombination  

SciTech Connect

The polarization dependence of laser-induced radiative recombination (LIR) to D{sup +} ions was investigated in the electron cooler of the CRYRING storage ring. The LIR gain as a function of wavelength into n = 3 principal quantum states of deuterium was measured at laser beam polarization angles of 0 deg. and 90 deg. with respect to the direction of the motional electric field in the interaction region. For the case of the polarization vector parallel to the external field, there is a double-peak structure in the gain curve that indicates a polarization effect in the LIR process. The two polarization directions also reveal a different width for the respective gain curves, giving additional evidence for the polarization effect, clearly seen by the behavior of a defined polarization parameter. The obtained polarization effect indicates a high sensitivity in recombination processes to external fields.

Mohamed, T.; Fogle, M.; Madzunkov, S.; Schuch, R. [Department of Physics, Atomic Physics, Stockholm University, S-106 91 Stockholm (Sweden); Andler, G. [Manne Siegbahn Laboratory, Stockholm University, S-10405 Stockholm (Sweden); Justiniano, E. [Department of Physics, East Carolina University, Greenville, North Carolina 27858 (United States)

2011-03-15

217

Power Spectral Analysis of Recovery Sleep of Sleep Deprivation and Hypnotic Drug Induced Sleep  

Microsoft Academic Search

Hypnotic drugs induced sleep is usually different from physiological sleep in restoring body energy. The cause of the differences is not clear. To investigate the differences between these two types of sleep, in this study, hypnotic drug diazepam (DZP) induced sleep was compared with the recovery sleep following sleep deprivation. Power spectral analysis was used to reveal the different EEG

Zhouyan Feng; Fei Gu

2005-01-01

218

Ocean color spectral variability studies using solar-induced chlorophyll fluorescence  

NASA Technical Reports Server (NTRS)

It is suggested that chlorophyll-induced ocean color spectral variability can be studied using only a passive airborne spectroradiometer instrument, with solar-induced chlorophyll fluorescence used as the standard against which all correlations are performed. The intraspectral correlation (ISC) method is demonstrated with results obtained during an airborne mapping mission in the New York Bight. The curvature algorithm is applied to the solar-induced chlorophyll fluorescence at about 690 nm, and good agreement is found with results obtained using active-passive correlation spectroscopy. The ISC method has application to spectral variability and resulting chlorophyll concentration measurement in different environmental conditions and in different water types.

Hoge, Frank E.; Swift, Robert N.

1987-01-01

219

Modulation of TNF-induced macrophage polarization by synovial fibroblasts.  

PubMed

Mesenchymal stromal cells have emerged as powerful modulators of the immune system. In this study, we explored how the human macrophage response to TNF is regulated by human synovial fibroblasts, the representative stromal cell type in the synovial lining of joints that become activated during inflammatory arthritis. We found that synovial fibroblasts strongly suppressed TNF-mediated induction of an IFN-? autocrine loop and downstream expression of IFN-stimulated genes (ISGs), including chemokines CXCL9 and CXCL10 that are characteristic of classical macrophage activation. TNF induced the production of soluble synovial fibroblast factors that suppressed the macrophage production of IFN-?, and cooperated with TNF to limit the responsiveness of macrophages to IFN-? by suppressing activation of Jak-STAT signaling. Genome-wide transcriptome analysis showed that cocultured synovial fibroblasts modulate the expression of approximately one third of TNF-regulated genes in macrophages, including genes in pathways important for macrophage survival and polarization toward an alternatively activated phenotype. Pathway analysis revealed that gene expression programs regulated by synovial fibroblasts in our coculture system were also regulated in rheumatoid arthritis synovial macrophages, suggesting that these fibroblast-mediated changes may contribute to rheumatoid arthritis pathogenesis. This work furthers our understanding of the interplay between innate immune and stromal cells during an inflammatory response, one that is particularly relevant to inflammatory arthritis. Our findings also identify modulation of macrophage phenotype as a new function for synovial fibroblasts that may prove to be a contributing factor in arthritis pathogenesis. PMID:25057003

Donlin, Laura T; Jayatilleke, Arundathi; Giannopoulou, Eugenia G; Kalliolias, George D; Ivashkiv, Lionel B

2014-09-01

220

Basic program "IPFLTR" for induced polarization data reduction and filtering  

USGS Publications Warehouse

The recently developed induced polarization (IP) mapping technique can be successfully applied to IP dipole-dipole data and includes three types of filters that can be applied to IP pseudosections that have IP anomalies caused by different types of sources. The technique yields a single output value per station; this value reflects all levels of the pseudosection and is suitable for contouring in plan view. It also provides a quantitative picture of IP anomalies in their background or regional settings. In the 'IPFLTR' program, the application of the three types of IP filters to the IP pseudosection data was programmed in BASIC. The program allows the user to reduce IP field data and to produce IP pseudosections. It includes three filter subprograms, which calculate output data from each filter. The filtered data include a single reading for each station along the pseudosection. These data can be presented as individual IP profiles, or several profiles can be contoured together to produce an IP map. The program can optionally provide simple or complex plots either of the filtered data or of any selected level in the pseudosection.

Sadek, Hamdy S.

1983-01-01

221

Magnetospheric Birefringence Induces Unique Polarization Signatures in Neutron-Star Spectra  

E-print Network

We study the propagation of polarization light through the magnetosphere of neutron stars. At intermediate frequencies (the optical through the infrared), both the birefringence induced by the plasma and by quantumelectrodynamics influence the observation polarization of radiation from the surface of the neutron star. Because these two processes compete in this regime, we find that polarization observations can constrain the properties of the neutron-star magnetosphere, specifically the total charge density. We calculate both the phase-resolved and the phase-averaged polarization signatures induced by magnetospheric birefringence.

R. M. Shannon; Jeremy S. Heyl

2004-10-22

222

Polarization manipulation based on electromagnetically induced transparency-like (EIT-like) effect.  

PubMed

We proposed, designed and fabricated a high transparency of metasurface-based polarization controller at microwave frequencies, which consists of orthogonal two pairs of cut wires. The high transmission and the strong dispersion properties governed by electromagnetically induced transparency-like (EIT-like) effects for both incident polarizations make our device efficiently manipulating the polarization of EM waves. In particular, the proposed polarization device is ultrathin (~0.017?), as opposed to bulky polarization devices. Microwave experiments are performed to successfully demonstrate our ideas, and measured results are in reasonable agreement with numerical simulations. PMID:24514804

Zhu, Lei; Meng, Fan-Yi; Dong, Liang; Fu, Jia-Hui; Zhang, Fang; Wu, Qun

2013-12-30

223

Geometric phase and Pancharatnam phase induced by light wave polarization  

E-print Network

We use the quantum kinematic approach to revisit geometric phases associated with polarizing processes of a monochromatic light wave. We give the expressions of geometric phases for any, unitary or non-unitary, cyclic or non-cyclic transformations of the light wave state. Contrarily to the usually considered case of absorbing polarizers, we found that a light wave passing through a polarizer may acquire in general a non zero geometric phase. This geometric phase exists despite the fact that initial and final polarization states are in phase according to the Pancharatnam criterion and can not be measured using interferometric superposition. Consequently, there is a difference between the Pancharatnam phase and the complete geometric phase acquired by a light wave passing through a polarizer. We illustrate our work with the particular example of total reflection based polarizers.

J. Lages; R. Giust; J. -M. Vigoureux

2013-12-03

224

Adaptation of the University of Wisconsin High Spectral Resolution Lidar for Polarization and Multiple Scattering Measurements  

NASA Technical Reports Server (NTRS)

A new implementation of the High Spectral Resolution Lidar (HSRL) in an instrument van which allows measurements during field experiments is described. The instrument was modified to provide measurements of depolarization. In addition, both the signal amplitude and depolarization variations with receiver field of view are simultaneously measured. These modifications allow discrimination of ice clouds from water clouds and observation of multiple scattering contributions to the lidar return.

Eloranta, E. W.; Piironen, P. K.

1992-01-01

225

Sudden Death of Entanglement induced by Polarization Mode Dispersion  

E-print Network

We study the decoherence of polarization-entangled photon pairs subject to the effects of polarization mode dispersion, the chief polarization decoherence mechanism in optical fibers. We show that fiber propagation reveals an intriguing interplay between the concepts of entanglement sudden death, decoherence-free sub-spaces and non-locality. We define the boundaries in which entanglement-based quantum communications protocols relying on fiber propagation can be applied.

Cristian Antonelli; Mark Shtaif; Misha Brodsky

2011-01-27

226

Spectral-integral representation of the photon polarization operator in a constant uniform magnetic field  

E-print Network

The polarization operator in a constant and homogeneous magnetic field of arbitrary strength is investigated on mass shell. The calculations are carried out at all photon energies higher the pair creation threshold as well as lower this threshold. The general formula for the effective mass of the photon with given polarization has been obtained being useful for an analysis of the problem under consideration as well as at a numerical work. Approximate expressions for strong or weak fields, compared with the critical field, have been found. Depending on the ratio of these fields we consider the pure quantum region of photon energy, where particles are created on lower Landau levels or created not at all. Also the energy region of large level numbers is considered where the quasiclassical approximation is valid.

V. M. Katkov

2014-11-10

227

Spectral-integral representation of the photon polarization operator in a constant uniform magnetic field  

E-print Network

The polarization operator in a constant and homogeneous magnetic field of arbitrary strength is investigated on mass shell. The calculations are carried out at all photon energies higher the pair creation threshold as well as lower this threshold. The general formula for the effective mass of the photon with given polarization has been obtained being useful for an analysis of the problem under consideration as well as at a numerical work. Approximate expressions for strong or weak fields, compared with the critical field, have been found. Depending on the ratio of these fields we consider the pure quantum region of photon energy, where particles are created on lower Landau levels or created not at all. Also the energy region of large level numbers is considered where the quasiclassical approximation is valid.

Katkov, V M

2014-01-01

228

UVCS\\/SOHO Observations of Spectral Line Profiles in Polar Coronal Holes  

Microsoft Academic Search

Ultraviolet emission line profiles have been measured on 15-29 September 1997 for H I 1216 , O VI 1032, 1037 and Mg X 625\\u000a in a polar coronal hole, at heliographic heights ? (in solar radii) between 1.34 and 2.0. Observations of H I 1216 and\\u000a the O VI doublet from January 1997 for ? = 1.5 to 3.0 are

J. L. Kohl; S. Fineschi; R. Esser; A. Ciaravella; S. R. Cranmer; L. D. Gardner; R. Suleiman; G. Noci; A. Modigliani

1999-01-01

229

Lambda and Lambda-bar Polarization in Lepton Induced Processes  

E-print Network

The study of the longitudinal polarization of Lambda and Lambda-bar hyperons produced in polarized deep inelastic scattering, neutrino scattering, and in Z0 decays allows to access the spin dynamics of the quark fragmentation process. Different phenomenological spin transfer mechanisms are considered and predictions for the Lambda and Lambda-bar longitudinal polarization in various processes using unpolarized and polarized targets are made. Current and future semi-inclusive deep inelastic scattering experiments will provide soon accurate enough data to study these phenomena and distinguish between various models for the spin transfer mechanisms.

A. Kotzinian; A. Bravar; D. von Harrach

1997-01-27

230

Phase-resolved X-ray spectroscopy and spectral energy distribution of the X-ray soft polar RS Caeli  

NASA Astrophysics Data System (ADS)

Context. RS Cae is the third target in our series of XMM-Newton observations of soft X-ray-dominated polars. Aims: Our observational campaign aims to better understand and describe the multiwavelength data, the physical properties of the system components, and the short- and long-term behavior of the component fluxes in RS Cae. Methods: We employ stellar atmosphere, stratified accretion-column, and widely used X-ray spectral models. We fit the XMM-Newton spectra, model the multiband light curves, and opt for a mostly consistent description of the spectral energy distribution. Results: Our XMM-Newton data of RS Cae are clearly dominated by soft X-ray emission. The X-ray light curves are shaped by emission from the main accretion region, which is visible over the whole orbital cycle, interrupted only by a stream eclipse. The optical light curves are formed by cyclotron and stream emission. The XMM-Newton X-ray spectra comprise a black-body-like and a plasma component at mean temperatures of 36 eV and 7 keV. The spectral fits give evidence of a partially absorbing and a reflection component. Multitemperature models, covering a broader temperature range in the X-ray emitting accretion regions, reproduce the spectra appropriately well. Including archival data, we describe the spectral energy distribution with a combination of models based on a consistent set of parameters and derive a lower limit estimate of the distance d ? 750 pc. Conclusions: The high bolometric soft-to-hard flux ratios and short-term variability of the (X-ray) light curves are characteristic of inhomogeneous accretion. RS Cae clearly belongs in the group of polars that show a very strong soft X-ray flux compared to their hard X-ray flux. The different black-body fluxes and similar hard X-ray and optical fluxes during the XMM-Newton and ROSAT observations show that soft and hard X-ray emission are not directly correlated. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

Traulsen, I.; Reinsch, K.; Schwope, A. D.; Schwarz, R.; Walter, F. M.; Burwitz, V.

2014-02-01

231

General Theory for the Ferroelectric Polarization Induced by Spin-Spiral Order H. J. Xiang,1,* E. J. Kan,2  

E-print Network

General Theory for the Ferroelectric Polarization Induced by Spin-Spiral Order H. J. Xiang,1,* E. J polarization of triangular-lattice antiferromagnets induced by helical spin-spiral order is not explained a general theory for the ferroelectric polarization induced by spin-spiral order and then by evaluating

Gong, Xingao

232

PPARc Ligands Switched High Fat Diet-Induced Macrophage M2b Polarization toward M2a Thereby  

E-print Network

PPARc Ligands Switched High Fat Diet-Induced Macrophage M2b Polarization toward M2a Thereby the activation of alternative M2 macrophage polarization. Here, we evaluated the impact of high fat diet (HFD)-induced present a M2b polarization (TNF-ahigh , IL-10high , MR, Dectin-1). Interestingly, rosiglitazone induces

Boyer, Edmond

233

Detection and calculation of reflected spectral shifts in fiber-Bragg gratings (FBG) in polarization maintaining optical fiber  

NASA Astrophysics Data System (ADS)

Fiber-Bragg Gratings (FBG) for Structural Health Monitoring (SHM) have been studied extensively as they offer electrically passive operation, EMI immunity, high sensitivity, and multiple multiplexing schemes, as compared to conventional electricity based strain sensors. FBG sensors written in Polarization Maintaining (PM) optical fiber offer an additional dimension of strain measurement simplifying sensor implementation within a structure. This simplification however, adds complexity to the detection of the sensor's optical response to its corresponding applied strain. We propose a method that calculates spectral shifts caused by axial and traversal strains for PM FBG sensors. The system isolates the orthogonal propagating optical waves incident to the optical interrogators. The post-processing algorithm determines the wavelength shifts, and compares to a predetermined baseline then correlates the shift magnitudes to a respective strain. This exercise validates the method of optical detection and shift calculation of multi-axis sensors as an automated, integrated system.

Quintana, Joel; Gonzalez, Virgilio

2014-04-01

234

High-speed spectral domain polarization- sensitive optical coherence tomography using a single camera and an optical switch at 1.3 mum  

Microsoft Academic Search

We propose high-speed spectral domain polarization-sensitive optical coherence tomography (SD-PS-OCT) using a single camera and a 1×2 optical switch at the 1.3-mum region. The PS-low coherence interferometer used in the system is constructed using free-space optics. The reflected horizontal and vertical polarization light rays are delivered via an optical switch to a single spectrometer by turns. Therefore, our system costs

Sang-Won Lee; Hyun-Woo Jeong; Beop-Min Kim

2010-01-01

235

Fluorescence in situ hybridization and spectral imaging analysisof human oocytes and first polar bodies  

SciTech Connect

We investigated the frequencies of abnormalities involving either chromosome 1, 16, 18 or 21 in failed-fertilized human oocytes.While abnormalities involving chromosome 16 showed an age-dependant increase, results for the other chromosomes did not show statistically significant differences between the three age groups <35 yrs, 35-39 yrs, and >39 yrs. The scoring of four chromosomes is likely to underestimate the true rate of aneuploid cells. Thus, for a pilot study investigating a more comprehensive analysis of oocytes and their corresponding first polar bodies (1PBs), we developed a novel 8-probe chromosome enumeration scheme using FISH and SIm.

Weier, Heinz-Ulli G.; Weier, Jingly F.; Oter Renom, Maria; Zheng,Xuezhong; Colls, Pere; Nureddin, Aida; Pham, Chau D.; Chu, Lisa W.; Racowsky, Catherine; Munne, Santiago

2004-10-06

236

The inference of vector magnetic fields from polarization measurements with limited spectral resolution  

NASA Technical Reports Server (NTRS)

A method is presented for recovery of the vector magnetic field and thermodynamic parameters from polarization measurement of photospheric line profiles measured with filtergraphs. The method includes magneto-optic effects and may be utilized on data sampled at arbitrary wavelengths within the line profile. The accuracy of this method is explored through inversion of synthetic Stokes profiles subjected to varying levels of random noise, instrumental wave-length resolution, and line profile sampling. The level of error introduced by the systematic effect of profile sampling over a finite fraction of the 5 minute oscillation cycle is also investigated. The results presented here are intended to guide instrumental design and observational procedure.

Lites, B. W.; Skumanich, A.

1985-01-01

237

The effect of polarization on the light-induced conical intersection phenomenon  

NASA Astrophysics Data System (ADS)

It has already been shown that dressing of diatomic molecules by standing or running linear polarized laser waves gives rise to conical intersections (CIs). Due to the presence of such CIs, the rovibronic molecular motions are strongly coupled. Here we prove that only perfect linear polarized light induces CIs in diatomic molecules. However, the fingerprints of the light-induced conical intersection survive for an elliptical polarization but not for a circular polarization. Therefore, the effects of the light-induced conical intersection can be controlled by varying a physical parameter (polarization of the laser). Such a CI controllable physical parameter does not exist in field-free polyatomic molecules. An illustrative numerical example for a sodium dimer showing the dependence of the absorption spectrum of Na2 upon ellipticity is given.

Moiseyev, Nimrod; Šindelka, Milan

2011-06-01

238

Controlling the polarization rotation of an optical field via asymmetry in electromagnetically induced transparency  

NASA Astrophysics Data System (ADS)

We propose and experimentally demonstrate a mechanism to achieve coherent control of the polarization rotation of an optical field in a multilevel electromagnetically induced transparency (EIT) system in rubidium atoms. By choosing a properly polarized coupling field and transition energy levels, the symmetry of the atomic medium to the propagation of two orthogonal polarization components of a weak linearly polarized probe field can be broken, which leads to a coherently controlled rotation of the probe field polarization. This mechanism of coherently controlled optical polarization rotation makes use of asymmetry in EIT subsystems for the two circular polarization components of the probe beam with a contribution from different transition strengths (due to different Clebsh-Gordan coefficients) in this multilevel atomic system.

Wang, Bo; Li, Shujing; Ma, Jie; Wang, Hai; Peng, K. C.; Xiao, Min

2006-05-01

239

A Signaling Network Induced by ?2 Integrin Controls the Polarization of Lytic Granulesin Cytotoxic Cells  

PubMed Central

Cytotoxic lymphocyte skill target cells by polarized release of the content of perforin-containing granules. In natural killer cells, the binding of ?2 integrin to its ligand ICAM-1 is sufficient to promote not only adhesion but also lytic granule polarization. This provided a unique opportunity to study polarization in the absence of degranulation, and ?2 integrin signaling independently of inside-out signals from other receptors. Using an unbiased proteomics approach we identified a signaling network centered on an integrin-linked kinase (ILK)–Pyk2–Paxillin core that was required for granule polarization. Downstream of ILK, the highly conserved Cdc42–Par6 signaling pathway that controls cell polarity was activated and required for granule polarization. These results delineate two connected signaling networks induced upon ?2 integrin engagement alone, which are integrated to control polarization of the microtubule organizing center and associated lytic granules toward the site of contact with target cells during cellular cytotoxicity. PMID:25292215

Zhang, Minggang; March, Michael E.; Lane, William S.; Long, Eric O.

2014-01-01

240

Stress-induced polarization-graded ferroelectrics Joseph V. Mantese,a)  

E-print Network

of material systems, both by grading the composition of the ferroelectric and by imposing temperature spontaneous polar- ization, Ps is a function of material composition, c; tempera- ture, T; and stress, ; iStress-induced polarization-graded ferroelectrics Joseph V. Mantese,a) Norman W. Schubring, Adolph

Alpay, S. Pamir

241

Metamaterial with polarization and direction insensitive resonant transmission response mimicking electromagnetically induced transparency  

E-print Network

Metamaterial with polarization and direction insensitive resonant transmission response mimicking electromagnetically induced transparency N. Papasimakis,1 Y. H. Fu,1,2 V. A. Fedotov,1,a S. L. Prosvirnin,3 D. P. Tsai, the resonant transmission frequency of which does not depend on the polarization and angle of incidence

Zheludev, Nikolay

242

The Millennium Arecibo 21-cm Absorption Line Survey. III. Techniques for Spectral Polarization and Results for Stokes V  

E-print Network

We outline the theory and practice of measuring the four Stokes parameters of spectral lines in emission/absorption observations. We apply these concepts to our Arecibo HI absorption line data and present the results. We include a detailed discussion of instrumental effects arising from polarized beam structure and its interaction with the spatially extended emission line structure. At Arecibo, linear polarization (Stokes (Q,U)) has much larger instrumental effects than circular (Stokes V). We show how to reduce the instrumental contributions to V and to evaluate upper limits to its remaining instrumental errors by using the (Q,U) results. These efforts work well for opacity spectra but not for emission spectra. Arecibo's large central blockage exacerbates these effects, particularly for emission profiles, and other telescopes with weaker sidelobes are not as susceptible. We present graphical results for 41 sources; we analyze these absorption spectra in terms of Gaussian components, which number 136, and present physical parameters including magnetic field for each.

Carl Heiles T. H. Troland

2003-11-10

243

Light-Induced Polar pH Changes in Leaves of Elodea canadensis1  

PubMed Central

The effect of an extracellular electron acceptor, ferricyanide, on the light-induced polar leaf pH changes of the submerged angiosperm Elodea canadensis in light and in darkness was determined. The rate of transmembrane ferricyanide reduction was stimulated by increased light intensity and was inhibited by inorganic carbon, indicating that changes in the redox state of the chloroplast were reflected at the plasma membrane. The addition of ferricyanide inhibited the light-induced polar leaf pH reaction. This effect could be balanced by increasing the light intensity. In the dark, the acidification induced by ferricyanide was not influenced by diethylstilbestrol at concentrations that completely inhibited the polar leaf pH changes. This indicates that the ferricyanide-induced H+ extrusion and the H+ transport during the polar reaction were mediated by different mechanisms. PMID:16667045

Elzenga, J. Theo M.; Prins, Hidde B. A.

1989-01-01

244

Research on the Use of Induced Polarization Measurements to Study the Mechanical Properties of Unconsolidated Materials.  

National Technical Information Service (NTIS)

It has been suggested by previous investigators that measurements of induced polarization made on clay-bearing materials can be used to determine the permeability to fluids or the mechanical properties of those materials. A laboratory and field study was ...

G. V. Keller

1977-01-01

245

Multi-array borehole resistivity and induced polarization method with mathematical inversion of redundant data  

DOEpatents

Multiple arrays of electric or magnetic transmitters and receivers are used in a borehole geophysical procedure to obtain a multiplicity of redundant data suitable for processing into a resistivity or induced polarization model of a subsurface region of the earth.

Ward, Stanley H. (Salt Lake City, UT)

1989-01-01

246

Adaptation of the University of Wisconsin High Spectral Resolution Lidar for Polarization and Multiple Scattering Measurements  

NASA Technical Reports Server (NTRS)

Quantitative lidar measurements of aerosol scattering are hampered by the need for calibrations and the problem of correcting observed backscatter profiles for the effects of attenuation. The University of Wisconsin High Spectral Resolution Lidar (HSRL) addresses these problems by separating molecular scattering contributions from the aerosol scattering; the molecular scattering is then used as a calibration target that is available at each point in the observed profiles. While the HSRl approach has intrinsic advantages over competing techniques, realization of these advantages requires implementation of a technically demanding system which is potentially very sensitive to changes in temperature and mechanical alignments. This paper describes a new implementation of the HSRL in an instrumented van which allows measurements during field experiments. The HSRL was modified to measure depolarization. In addition, both the signal amplitude and depolarization variations with receiver field of view are simultaneously measured. This allows for discrimination of ice clouds from water clouds and observation of multiple scattering contributions to the lidar return.

Eloranta, E. W.; Piironen, P. K.

1996-01-01

247

Induced solitons formed by cross polarization coupling in a birefringent cavity fiber laser  

E-print Network

We report on the experimental observation of induced solitons in a passively mode-locked fiber ring laser with birefringence cavity. Due to the cross coupling between the two orthogonal polarization components of the laser, it was found that if a soliton was formed along one cavity polarization axis, a weak soliton was also induced along the orthogonal polarization axis, and depending on the net cavity birefringence, the induced soliton could either have the same or different center wavelengths to that of the inducing soliton. Moreover, the induced soliton always had the same group velocity as that of the inducing soliton. They form a vector soliton in the cavity. Numerical simulations confirmed the experimental observations.

Zhang, H; Zhao, L M; Tam, H Y

2009-01-01

248

Electron impact polarization of atomic spectral lines. I - A general theoretical scheme  

NASA Technical Reports Server (NTRS)

A suitable theoretical scheme able to describe, in a wide variety of astrophysical situations, the phenomenon of atomic line polarization by electron impact is developed. Starting from the general principles of quantum mechanics and assuming the Born approximation, the rate equations for the density matrix elements of a multilevel atomic system, interacting with a nonrelativistic electron beam having any kind of angular distribution, are derived in full generality. The resulting theory generalizes the previous ones by accounting for the collisional rates and the cross sections concerning both inelastic and superelastic collisions (in any geometrical situation), and, moreover, by taking into account the coherences among Zeeman sublevels split by a magnetic field. As an example of particular relevance, the general formulas derived in the first sections of the paper are subsequently particularized to the case of the electric dipole interaction.

Fineschi, Silvano; Degl'innocenti, Egidio L.

1992-01-01

249

Phase Resolved X-Ray Spectral Analysis of Intermediate Polars EX Hya and FO Aqr  

NASA Astrophysics Data System (ADS)

Intermediate Polars (IPs): EX Hya and FO Aqr whichs are a subclass of Cataclysmic Variables (CVs) where a white dwarf with magnetic field strength of about 1-10MG accretes material from a main sequence companion through a truncated disc. In this talk we present orbital and spin phase-resolved X-ray spectroscopy of EX Hya and orbital phase-resolved X-ray spectroscopy of FO Aqr. We utilize XMM-Newton archive data of these objects for analysis. We investigate the change of the source spectrum over the spin and orbital periods. This analysis enhances our understanding about the accretion structure in these systems, temperature and composition of the X-ray emitting region together with the structure of the outer accretion disc and absorption in the system

Pekön, Yakup; Balman, ?lölen

2014-01-01

250

Spectral Modifications and Polarization Dependent Coupling in Tailored Assemblies of Quantum Dots and Plasmonic Nanowires  

PubMed Central

The coupling of optical emitters with a nanostructured environment is at the heart of nano- and quantum optics. We control this coupling by the lithographic positioning of a few (1–3) quantum dots (QDs) along plasmonic silver nanowires with nanoscale resolution. The fluorescence emission from the QD-nanowire systems is probed spectroscopically, by microscopic imaging and decay time measurements. We find that the plasmonic modes can strongly modulate the fluorescence emission. For a given QD position, the local plasmon field dictates the coupling efficiency, and thus the relative weight of free space radiation and emission into plasmon modes. Simulations performed with a generic few-level model give very good agreement with experiment. Our data imply that the 2D degenerate emission dipole orientation of the QD can be forced to predominantly emit to one polarization component dictated by the nanowire modes. PMID:23968490

2013-01-01

251

Spectral distribution of the polarized radiation from standard accretion disks in Active Galactic Nuclei: Observational analysis  

NASA Astrophysics Data System (ADS)

Spectropolarimetric observations of a number of Active Galactic Nuclei obtained using the SCORPIO-2 aperture focal reducer installed on the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences are used to estimate physical parameters of these objects. The measured polarization and its wavelength dependence are consistent with the expectations of a standard accretion-disk model taking into account the effect of Faraday depolarization over the mean free path of the emitted photons. Estimates of the magnetic field in the accretion disk near the innermost stable orbit and the spin of the accreting central black hole are obtained. It is concluded that supermassive black holes with standard accretion disks and equal magnetic and radiative pressures are primarily Kerr black holes.

Afanas'ev, V. L.; Borisov, N. V.; Gnedin, Yu. N.; Buliga, S. D.; Natsvlishvili, T. M.; Piotrovich, M. Yu.

2014-10-01

252

Large ferroelectric polarization in the new double perovskite NaLaMnWO6 induced by non-polar instabilities.  

PubMed

Based on density functional theory calculations and group theoretical analysis, we have studied NaLaMnWO(6) compound which has been recently synthesized [G. King, A. Wills and P. M. Woodward, Phys. Rev. B: Condens. Matter, 2009, 79, 224428] and belongs to the AA'BB'O(6) family of double perovskites. At low temperature, the structure has monoclinic P2(1) symmetry, with layered ordering of the Na and La ions and rocksalt ordering of Mn and W ions. The Mn atoms show an antiferromagnetic collinear spin ordering, and the compound has been reported as a potential multiferroic. By comparing the low symmetry structure with a parent phase of P4/nmm symmetry, two distortion modes are found dominant. They correspond to MnO(6) and WO(6) octahedron tilt modes, often found in many simple perovskites. While in the latter these common tilting instabilities yield non-polar phases, in NaLaMnWO(6) the additional presence of the A-A' cation ordering is sufficient to make these rigid unit modes a source of the ferroelectricity. Through a trilinear coupling with the two unstable tilting modes, a polar distortion is induced, although the system has no intrinsic polar instability. The calculated electric polarization resulting from this polar distortion is as large as ?16 ?C cm(-2). Despite its secondary character, this polarization is coupled with the dominant tilting modes and its switching is bound to produce the switching of one of two tilts, enhancing in this way a possible interaction with the magnetic ordering. The transformation of common non-polar purely steric instabilities into sources of ferroelectricity through a controlled modification of the parent structure, as done here by the cation ordering, is a phenomenon to be further explored. PMID:21647478

Fukushima, T; Stroppa, A; Picozzi, S; Perez-Mato, J M

2011-07-14

253

Circular Polarization Induced by Scintillation in a Magnetized Medium  

E-print Network

A new theory is presented for the development of circular polarization as radio waves propagate through the turbulent, birefringent interstellar medium. The fourth order moments of the wavefield are calculated and it is shown that unpolarized incident radiation develops a nonzero variance in circular polarization. A magnetized turbulent medium causes the Stokes parameters to scintillate in a non-identical manner. A specific model for this effect is developed for the case of density fluctuations in a uniform magnetic field.

J. -P. Macquart; D. B. Melrose

2000-06-30

254

The dependence of induced polarization on natural iron concentration in wetland soils  

NASA Astrophysics Data System (ADS)

Spectral Induced polarization (SIP) measurements in the frequency range 0.1-1000 Hz were conducted on clay and peat marsh soils, obtained from a contaminated freshwater weltand in New Jersey, that were subsequently analyzed for heavy metal concentrations, moisture content, organic matter, porosity, specific surface area, and pore fluid conductivity. A Cole-Cole relaxation model was fit to each of the samples and the model parameters analyzed in terms of the measured physiochemical properties. A linear relationship between the normalized chargeability (mn) and the estimated surface area to pore volume (Sp) is found when the iron content (ranging from 0.25 to 1.63 percent by volume between samples) is accounted for as a polarizable element of the soil. In fact, the dependence of mn on volumetric Fe concentration per unit volume of the bulk soil is described by a linear relationship with a correlation coefficient of 0.94. As the Fe concentration of soils is a critical biogeochemical parameter, these results suggest that SIP measurements may provide a hitherto unrecognized approach to probing soil geochemistry, iron cycling and anaerobic microbial activity. Furthermore, our results yield new insight into the physiochemical controls on SIP in natural, unconsolidated soils.

Slater, L. D.; Mansoor, N.

2006-12-01

255

Interaction induced deformation in momentum distribution of spin polarized nuclear matter  

E-print Network

Effects of spin polarization on the structure of symmetric nuclear matter and pure neutron matter are investigated. We show that the spin polarization induces a deformation of the Fermi spheres for nucleons with spin parallel and opposite to the polarization axes. This feature can be related to the structure of the one pion exchange contribution to a realistic nucleon-nucleon interaction. While the anisotropies in the momentum distribution lower the energy of the system by small amount, the associated variations of the single particle energies with the angle between the polarization axis and the particle momentum are significant.

T. Frick; H. Müther; A. Sedrakian

2002-03-19

256

Fluorescent probing of protein bovine serum albumin stability and denaturation using polarity sensitive spectral response of a charge transfer probe.  

PubMed

The polarity sensitive photo-induced intra-molecular charge transfer (ICT) fluorescence probe (E)-3-(4-methylamino-phenyl)-acrylic acid ethyl ester (MAPAEE) has been used to study the model protein Bovine Serum Albumin (BSA) in its native and thermal and urea induced denatured states. The interaction between BSA and the regular surfactant Sodium Dodecyl Sulphate (SDS) as well as the biologically relevant steroid-based amphiphile Sodium Deoxycholate (NaDC) has also been very keenly followed using this ICT probe. The variation of micellar properties of both SDS and NaDC with increasing ionic strengths and in presence of the chaotrope urea has also been well documemted by the same probe. Steady-state spectroscopy, FRET, and fluorescence anisotropy measurements have been used to gain better insight into these processes and the molecule MAPAEE to be a full-bodied fluorescent probe for studying such intricate biological systems, their properties and interactions. PMID:20922468

Ghosh, Shalini; Jana, Sankar; Nath, Debnarayan; Guchhait, Nikhil

2011-01-01

257

Postselection of a polarization basis in intensity correlations under electromagnetically induced transparency  

NASA Astrophysics Data System (ADS)

We report on switching the intensity correlation or anticorrelation by changing the polarization basis for measuring light that has already propagated through the electromagnetically induced transparency (EIT) medium of the 5S1/2(F=2)-5P1/2(F'=1) transition of Rb87 atoms. When a linearly polarized laser beam interacts with the EIT medium in the Hanle configuration, selection of the polarization basis after the optical field has already interacted with the atoms was found to significantly affect the intensity-intensity correlation of the two orthogonal polarization components. We compared the second-order correlation functions of two postselected polarization bases (linear and circular), and the polarization basis effect on the second-order correlation functions as a function of the applied magnetic field was numerically calculated using an eight-level atomic model.

Lee, Hee Jung; Jeong, Taek; Moon, Han Seb

2014-09-01

258

POLARIZATION OF THE CHARGE-EXCHANGE X-RAYS INDUCED IN THE HELIOSPHERE  

SciTech Connect

We report results of a theoretical investigation of polarization of the X-ray emissions induced in charge-exchange collisions of fully stripped solar wind (SW) ions C{sup 6+} and O{sup 8+} with the heliospheric hydrogen atoms. The polarization of X-ray emissions has been computed for line-of-sight observations within the ecliptic plane as a function of SW ion velocities, including a range of velocities corresponding to the slow and fast SW, and coronal mass ejections. To determine the variability of polarization of heliospheric X-ray emissions, the polarization has been computed for solar minimum conditions with self-consistent parameters of the SW plasma and heliospheric gas and compared with the polarization calculated for an averaged solar activity. We predict the polarization of charge-exchange X-rays to be between 3% and 8%, depending on the line-of-sight geometry, SW ion velocity, and the selected emission lines.

Gacesa, M.; Kharchenko, V. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mueller, H.-R. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Cote, R., E-mail: gacesa@phys.uconn.edu [Physics Department, University of Connecticut, 2152 Hillside Road, Storrs, CT 06269 (United States)

2011-05-10

259

Spectral analysis of seismic noise induced by rivers: A new tool to monitor spatiotemporal changes in  

E-print Network

Spectral analysis of seismic noise induced by rivers: A new tool to monitor spatiotemporal changes and deeply incised channel of the Trisuli River, a major trans-Himalayan river. The early summer increase the Trisuli River. Seasonal increase in ambient noise coincides with the strong monsoon rainfall and a period

Demouchy, Sylvie

260

Field-resolved measurement of reaction-induced spectral densities by polarizability response spectroscopy  

E-print Network

of solvent as opposed to solute dynamics coupled to the reaction. The sign of the signal representsField-resolved measurement of reaction-induced spectral densities by polarizability response and off-resonant Raman spectra of the resulting nuclear motions are measured as a function of the reaction

Scherer, Norbert F.

261

Interfacial polarization and pyroelectricity in antiferrodistortive structures induced by a flexoelectric effect and rotostriction  

NASA Astrophysics Data System (ADS)

Theoretical analysis based on the Landau-Ginzburg-Devonshire theory is used to show that the combined effect of flexoelectricity and rotostriction can lead to a spontaneous polarization and pyroelectricity in the vicinity of antiphase boundaries, structural twin walls, surfaces, and interfaces in the octahedrally tilted phase of otherwise nonferroelectric perovskites such as CaTiO3, SrTiO3, and EuTiO3. As an example, we numerically demonstrate a spontaneous polarization and pyroelectric response at the SrTiO3 antiphase and twin boundaries at temperatures lower than the antiferrodistortive structural phase transition temperature of TS˜105 K in agreement with previously unexplained experimental results. At temperatures lower than effective Curie temperature TC* (˜25 K for twins and ˜50 K for antiphase boundaries) biquadratic coupling between oxygen octahedron tilt and polarization vectors essentially enhances the polarization induced by the combined flexoelectric and rotostriction effects near the hard domain wall. Biquadratic coupling cannot induce polarization inside easy twins and antiphase boundaries; their polarization and pyroelectricity originates below TS from the built-in flexoelectric field. The spontaneous polarization reaches the values ˜0.1-5 ?C/cm2 at the SrTiO3 antiphase boundaries and twins without free charges. A principal difference between the influence of biquadratic and flexoelectric couplings on the interfacial polarization is the following: the biquadratic coupling induces bistable ferroelectric polarization inside hard antiphase boundaries and hard twins below TC*, while the flexoelectric coupling induces improper spontaneous polarization via the flexoelectric field below TS.

Morozovska, Anna N.; Eliseev, Eugene A.; Glinchuk, Maya D.; Chen, Long-Qing; Gopalan, Venkatraman

2012-03-01

262

Polarization conversion in ring resonator phase shifters.  

PubMed

The effect of the polarization rotation induced by curved waveguides on the spectral behavior of phase shifter ring resonators is investigated both theoretically and experimentally. At resonance the polarization rotation that takes place in curved waveguides is strongly enhanced. The effect can be detrimental, or it can be exploited for new devices. The ring vectorial transfer function is derived, together with the conditions for the total conversion of TE polarization into TM polarization. These conditions are verified experimentally. PMID:15605505

Melloni, Andrea; Morichetti, Francesco; Martinelli, Mario

2004-12-01

263

Strain-Induced Polarization Rotation in Epitaxial (001) BiFeO3 Thin Films H. W. Jang,1  

E-print Network

Strain-Induced Polarization Rotation in Epitaxial (001) BiFeO3 Thin Films H. W. Jang,1 S. H. Baek,1 analysis reveals that a strain-induced polarization rotation mechanism is responsible for the large change measurement of the remanent polarization of high quality (001)-oriented epitaxial BiFeO3 thin films shows

Eom, Chang Beom

264

Polar-surface dominated ZnO nanobelts and the electrostatic energy induced nanohelixes, nanosprings, and nanospirals  

E-print Network

#12;Polar-surface dominated ZnO nanobelts and the electrostatic energy induced nanohelixes for understanding piezoelectricity and polarization induced phenomena at nanoscale. © 2004 American Institute are dominated by the large polar surfaces. The nanobelts grow along the a axis, their large top/bottom surfaces

Wang, Zhong L.

265

CMB-induced Cluster Polarization as a Cosmological Probe  

E-print Network

Scattering of the temperature anisotropy quadrupole by free electrons in galaxy clusters leads to a secondary polarization signal in the cosmic microwave background (CMB) fluctuations. At low redshifts, the temperature quadrupole contains a significant contribution from the integrated Sachs-Wolfe (ISW) effect associated with the growth of density fluctuations. Using polarization data from a sample of clusters over a wide range in redshift, one can statistically establish the presence of the ISW effect and determine its redshift evolution. Given the strong dependence of the ISW effect on the background cosmology, cluster polarization can eventually be used as a powerful probe of dark energy. As a further application, we also discuss how it might be used to understand the potential lack of power on large scales.

Daniel Baumann; Asantha Cooray

2003-04-23

266

Mechanism of polarization-induced single-photon fluorescence enhancement  

NASA Astrophysics Data System (ADS)

The single-photon fluorescence (SPF) of IR125 can be enhanced when the laser polarization changes from linear through elliptical to circular [A. Nag and D. Goswami, J. Chem. Phys. 132, 154508 (2010)]. In this paper, we further explain and discuss the physical control mechanism. Our theoretical and experimental results demonstrate that the SPF enhancement can be attributed to the nonresonant two-photon absorption of a higher excited state. We conclude that the SPF intensity involving the nonresonant multiphoton absorption of the higher excited state can be controlled by varying the laser polarization.

Zhang, Shian; Zhang, Hui; Lu, Chenhui; Jia, Tianqing; Wang, Zugeng; Sun, Zhenrong

2010-12-01

267

Continental lithospheric thickness and deglaciation induced true polar wander  

Microsoft Academic Search

Geophysical data are presented which strongly suggest a continental lithospheric thickness in excess of 250 km. The data are based on the polar motion record collected by the International Latitude Service since 1900. It is found that the dominant oscillatory signal produced by the 7 year beat between the 14 month Chandler wobble and the 12 month annual wobble is

W. R. Peltier; Patrick Wu

1983-01-01

268

A meteorological model for rain-induced cross polarization  

Microsoft Academic Search

After a brief summary of the existing theory on microwave attenuation and cross polarization by rain and of the supporting experimental evidence, the paper gives a physical explanation of raindrop canting. It is shown that vertical windgradients are a cause of canting. A model for the dependence of windspeed on height is then employed to calculate actual values of canting

GERT BRUSSAARD

1976-01-01

269

Confinement Induced Quantum Phase Transition and Polarization Cooling in a Dipolar Crystal of Polar Molecules  

E-print Network

It is well-known that the liquid properties in a strongly confined system can be very different from their ordinary behaviors in an extended system, due to the competition between the thermal energy and the interaction energy. Here we show that, in a low-dimensional self-assembled dipolar crystal, the parabolic optical confinement potential can also strongly affect the quantum many-body properties in the low temperature regime. For example, by changing the confinement aspect ratio, the bulk of the system can undergo a quantum phase transition between a liquid state and a solid state via a nonmonotonic pattern formation of the domain wall. Furthermore, the entropy of a trapped dipolar crystal can be much larger than the liquid state in the weak dipole limit, indicating an intrinsic polarization cooling mechanism via increasing the external field. These highly correlated confinement effects are very important to the experimental preparation of a self-assembled dipolar crystal using ultracold polar molecules.

Yi-Ya Tian; Daw-Wei Wang

2008-08-09

270

Wide-angle and polarization-independent electromagnetically induced transparency-like effect based on pentacyclic structure  

NASA Astrophysics Data System (ADS)

A pentacyclic structure analog wide-angle and polarization-independent electromagnetically induced transparency-like (EIT-like) effect is numerically and experimentally demonstrated. The unit cell of the structure is composed of four identical circular inner rings surrounded by a larger circular outer ring. A wide-angle and polarization-independent transparency window is clearly observed in the spectral overlapping region of absorption bands of the inner and outer rings. The resonant feature of the transparency effect is investigated by the surface current distribution. We find that the coupling fields between rings play key roles and lead to the classical EIT-like effect. It is also shown that the polarization direction in our structure can be used to tune the position of the localized electric field enhancement. In addition, the effective group index and the effective refractive index are extracted to verify the slow light property with low loss. It is shown that our structure can reduce the group velocity of light by a factor of 64.

Zhu, Lei; Dong, Liang; Meng, Fan Yi; Wu, Qun

2014-01-01

271

Cyclooxygenase-2 inhibition attenuates hypoxic cancer cells induced m2-polarization of macrophages.  

PubMed

Tumor associated macrophages (TAMs), represent a major subpopulation of tumor infiltrating immune cells. These alternatively activated M2—polarized macrophages are well known for their pro—tumor functions. Owing to their established role in potentiating tumor—neovasculogenesis and metastasis, TAMs have emerged as promising target for anti—cancer immunotherapy. One of the key TAMs related phenomenon that is amenable to therapeutic intervention is their phenotype switching into alternatively activated M2—polarized macrophages. Hindering macrophage polarization towards a pro—tumor M2 phenotype, or better still reprogramming the M2 like TAMs towards M1 subtype is being considered a beneficial anti—cancer strategy. Hypoxic tumor milieu has been proposed as one of the most plausible factor governing M2—polarization of macrophages. We recently demonstrated that hypoxic tumor cells imparted a pro—angiogenic M2 skewed phenotype to macrophages. Furthermore, sizeable body of data indicates for participation of cyclooxygenase—2 (COX—2) in macrophage polarization. Concordantly, inhibition of COX—2 is associated with impaired macrophage polarization. Prompted by this in the current study we decided to explore if inhibition of COX—2 activity via chemical inhibitors may prevent hypoxic cancer cell induced M2—polarization of macrophages. We observed that treatment with Flunixin meglumine, an established preferential inhibitor of COX—2 activity markedly inhibited hypoxic cancer cell induced of M2—polarization of macrophages thereby indicating for usage of COX—2 inhibition as possible anti—cancer treatment modality. PMID:25210855

Dubey, P; Shrivastava, R; Tripathi, C; Jain, N K; Tewari, B N; Lone, M-U-D; Baghel, K S; Kumar, V; Misra, S; Bhadauria, S; Bhatt, M L B

2014-01-01

272

Elemental analysis of laser induced breakdown spectroscopy aided by an empirical spectral database.  

PubMed

Laser induced breakdown spectroscopy (LIBS) is commonly used to identify elemental compositions of various samples. To facilitate this task, we propose the use of an elemental spectral library for single-pulsed, nanosecond LIBS in the spectral range 198-968 nm. This spectroscopic library is generated by measuring optical emissions from plasmas of 40 pure elements. To demonstrate the usefulness of the proposed database, we measure and analyze the LIBS spectra of pure iron and of ethanol and show that we identify these samples with a high degree of certainty. PMID:19122709

Rock, Steven; Marcano, Aristides; Markushin, Yuri; Sabanayagam, Chandran; Melikechi, Noureddine

2008-11-01

273

Direct experimental measurement of SRS-induced spectral tilt in multichannel multispan communication systems  

NASA Astrophysics Data System (ADS)

Nonlinear SRS-induced tilt of the spectrum of a multichannel DWDM signal is studied experimentally in standard singlemode fibreoptic communication lines. It is found that at a fixed spectral bandwidth and total power the nonlinear SRS tilt is independent of the number of channels, radiation source type, and the initial tilt (positive or negative). In a multispan line consisting of identical spans the total nonlinear tilt of the spectrum (in dB) is proportional to the number of spans, spectral width and total power.

Kapin, Yu A.; Nanii, Oleg E.; Novikov, A. G.; Pavlov, V. N.; Plotskii, A. Yu; Treshchikov, V. N.

2012-09-01

274

Direct experimental measurement of SRS-induced spectral tilt in multichannel multispan communication systems  

SciTech Connect

Nonlinear SRS-induced tilt of the spectrum of a multichannel DWDM signal is studied experimentally in standard singlemode fibreoptic communication lines. It is found that at a fixed spectral bandwidth and total power the nonlinear SRS tilt is independent of the number of channels, radiation source type, and the initial tilt (positive or negative). In a multispan line consisting of identical spans the total nonlinear tilt of the spectrum (in dB) is proportional to the number of spans, spectral width and total power. (optical fibres, lasers and amplifiers. properties and applications)

Kapin, Yu A; Nanii, Oleg E; Novikov, A G; Pavlov, V N; Plotskii, A Yu; Treshchikov, V N

2012-09-30

275

Elemental analysis of laser induced breakdown spectroscopy aided by an empirical spectral database  

SciTech Connect

Laser induced breakdown spectroscopy (LIBS) is commonly used to identify elemental compositions of various samples. To facilitate this task, we propose the use of an elemental spectral library for single-pulsed, nanosecond LIBS in the spectral range 198-968 nm. This spectroscopic library is generated by measuring optical emissions from plasmas of 40 pure elements. To demonstrate the usefulness of the proposed database, we measure and analyze the LIBS spectra of pure iron and of ethanol and show that we identify these samples with a high degree of certainty.

Rock, Steven; Marcano, Aristides; Markushin, Yuri; Sabanayagam, Chandran; Melikechi, Noureddine

2008-11-01

276

A new strategy for in vivo spectral editing. Application to GABA editing using selective homonuclear polarization transfer spectroscopy  

NASA Astrophysics Data System (ADS)

A novel single-shot in vivo spectral editing method is proposed in which the signal to be detected, is regenerated anew from the thermal equilibrium magnetization of a source to which it is J-coupled. The thermal equilibrium magnetization of the signal to be detected together with those of overlapping signals are suppressed by single-shot gradient dephasing prior to the signal regeneration process. Application of this new strategy to in vivo GABA editing using selective homonuclear polarization transfer allows complete suppression of overlapping creatine and glutathione while detecting the GABA-4 methylene resonance at 3.02 ppm with an editing yield similar to that of conventional editing methods. The NAA methyl group at 2.02 ppm was simultaneously detected and can be used as an internal navigator echo for correcting the zero order phase and frequency shifts and as an internal reference for concentration. This new method has been demonstrated for robust in vivo GABA editing in the rat brain and for study of GABA synthesis after acute vigabatrin administration.

Shen, Jun; Yang, Jehoon; Choi, In-Young; Li, Shizhe Steve; Chen, Zhengguang

2004-10-01

277

Longitudinal field-induced polarized light transmittance of magnetic fluids  

NASA Astrophysics Data System (ADS)

The complete optical transmittance for a polarized light passing through the magnetic fluids is investigated theoretically and experimentally, when the externally magnetic field is applied along the propagation direction of the incident light. Hybrid effects due to the geometric shadowing and Faraday rotation are considered simultaneously. The Langevin-like functions are employed to describe the magnetic-field-dependent volume concentration of the particle-aggregation ( ?') and the approximate number of magnetic nanoparticles in the particle-aggregation ( ?N0). Based on the experiments on the geometric shadowing effect of our magnetic fluid sample, the analytical expression for the total transmitted power with externally magnetic field after an analyzer is derived. Theoretical simulations disclose the influence of certain critical parameters of the magnetic fluids on the field-dependent optical transmittance. For the entire polarized light transmittance, qualitative agreement between the calculations and the experiments is achieved. Applications of magnetic fluids to several polarized devices operating in longitudinal field arrangement are proposed and discussed. The results presented in this work may be useful for designing the corresponding magnetic-fluid-based optical devices.

Pu, Shengli; Dai, Min; Sun, Guoqing

2010-10-01

278

Incidence Angle and Polarization Dependence of Photo-Induced FMR in Co/Pd Multilayers  

E-print Network

Dependence of photo-induced FMR (phi-FMR) on incident angle of excitation and probing laser beams has been studied in a [Co (dCo = 0.78 nm) / Pd (dPd = 0.81 nm) ]5 multi-layer film with the aim to find experimentally the limitation of inducement and detection of magnetization dynamics with oblique light incidence. We have found, in the experiments changing the incident angle of a pump beam, that phi-FMR is observed up to the grazing incident angle of 88 degrees with p-polarized excitation pulses, whereas it disappears at the incidence angle of around 65 degrees with s-polarized excitation. As for the experiments changing the incident angle of a probe beam, phi-FMR disappears at the incidence angle of 65 degrees for both s- and p-polarizations, whereas it reappears with further increasing the angle for the p-polarization and vanishes at 75 degrees.

Saeki, J; Matsuda, T; Kitamoto, Y; Munekata, H

2014-01-01

279

Interference of spin states in resonant photoemission induced by circularly polarized light from magnetized Gd  

SciTech Connect

We have observed the spin-state interference by measuring the photoelectron spin polarization in the resonant preedge 4d{yields}4f photoemission from magnetized Gd. The photoemission is induced by circularly polarized light which determines one preferential direction of electron spin orientation due to polarization transfer and spin-orbit interaction. Another direction perpendicular to the first one is determined by the target electron spin orientation connected with the target magnetization. We have measured the component of spin polarization perpendicular to those two directions which can only appear due to spin-state interference which implies coherence of the spin states produced by the two mechanisms of the photoelectron spin polarization.

Mueller, N.; Khalil, T.; Pohl, M.; Uphues, T.; Heinzmann, U. [Fakultaet fuer Physik, Universitaet Bielefeld, D-33615 Bielefeld (Germany); Polcik, M. [Fritz-Haber-Institut der MPG, D-14195 Berlin (Germany); Rader, O. [BESSY, D-12489 Berlin (Germany); Heigl, F.; Starke, K. [Freie Universitaet Berlin, Fachbereich Physik, D-14195 Berlin (Germany); Fritzsche, S. [Institut fuer Physik, Universitaet Kassel, D-34132 Kassel (Germany); Kabachnik, N. M. [Fakultaet fuer Physik, Universitaet Bielefeld, D-33615 Bielefeld (Germany); Institute of Nuclear Physics, Moscow State University, Moscow 119992 (Russian Federation)

2006-10-15

280

Passive polarization agile antenna based on the electromagnetically induced transparency-like effect  

NASA Astrophysics Data System (ADS)

We propose a design method for a passive polarization agile antenna based on the electromagnetically induced transparency-like (EIT-like) effect. Benefiting from strong dispersion properties governed by EIT-like effects, the proposed structure can endow electromagnetic waves transmitted through it with quite different polarization states at very close frequencies. The experimental measurement was conducted to demonstrate agile polarization controls by placing a designed EIT-like waveplate in front of a standard microwave horn antenna. Results show that the polarization state of radiated waves by the horn antenna with a waveplate can be easily transformed among linear, circular and elliptical polarizations through fine-tuning the operating frequency, which is extremely important for certain special applications, e.g. electronic countermeasures. Our scheme could also be utilized at higher operating frequencies by the simply scaling principle.

Zhu, Lei; Meng, Fan-Yi; Wu, Qun; Dong, Liang; Chen, Wan; Fu, Jia-Hui

2014-10-01

281

Infrared spectral measurements (450-2500/cm) of shuttle-induced optical contamination  

NASA Astrophysics Data System (ADS)

The first shuttle-based infrared spectral measurements in the region beyond 800 nm were made during the STS-39 mission. A cryogenic Michelson interferometer in the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) payload yielded high quality atmospheric IR spectra in the earthlimb observing mode. In addition, observations in the very high earthlimb and in the bay-to-space mode provided important opportunities to assess optical contamination. These observations have revealed spectrally-extended H2O and NO emissions as dominant in the region 450-2500/cm under quiescent conditions. The viewing conditions, spectral and 'spatial' (limb scan) distributions, and temporal behavior of the H2O emissions have resulted in their classification as shuttle-induced 'cloud glow' optical contamination.

Zhou, D. K.; Pendleton, W. R., Jr.; Bingham, G. E.; Steed, A. J.; Dean, D. A.

1994-04-01

282

A Program Library for Forward Modelling and Inversion of DC Resistivity and Induced Polarization Data over 3D Structures  

E-print Network

D DC RESISTIVITY AND INDUCED POLARIZATION DATA UBC-Geophysical Inversion Facility Department about DC resistivity and Induced Polarization field experiments, but who is not necessarily versedDCIP3D A Program Library for Forward Modelling and Inversion of DC Resistivity and Induced

Oldenburg, Douglas W.

283

Zeno and Anti-Zeno Polarization Control of Spin Ensembles by Induced Dephasing Gonzalo A. A lvarez,1,2  

E-print Network

Zeno and Anti-Zeno Polarization Control of Spin Ensembles by Induced Dephasing Gonzalo A. A´ lvarez (polarization) control of qubits entangled with multiple spins, using induced dephasing in nuclear magnetic the bath-induced upward and downward transition rates in the qubit. By contrast, less frequent measurements

Frydman, Lucio

284

Optical signal processing based on self-induced polarization rotation in a semiconductor optical amplifier  

Microsoft Academic Search

We demonstrate novel optical signal processing functions based on self-induced nonlinear polarization rotation in a semiconductor optical amplifier (SOA). Numerical and experimental results are presented, which demonstrate that a nonlinear polarization switch can be employed to achieve all-optical logic. We demonstrate an all-optical header processing system, an all-optical seed pulse generator for packet synchronization, and an all-optical arbiter that can

N. Calabretta; Y. Liu; F. M. Huijskens; M. T. Hill; H. de Waardt; G. D. Khoe; H. J. S. Dorren

2004-01-01

285

Femtosecond Raman induced polarization spectroscopy studies of coherent rotational dynamics in molecular fluids  

SciTech Connect

We develop a polarization-sensitive femtosecond pump probe technique, Raman induced polarization spectroscopy (RIPS), to study coherent rotation in molecular fluids. By observing the collisional dephasing of the coherently prepared rotational states, we are able to extract information concerning the effects of molecular interactions on the rotational motion. The technique is quite sensitive because of the zero background detection method, and is also versatile due to its nonresonant nature.

Morgen, M.M. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley National Lab., CA (United States)

1997-05-01

286

Sign reversal of Hanle electromagnetically induced absorption with orthogonal circularly polarized optical fields  

NASA Astrophysics Data System (ADS)

We study by computation and experiment an electromagnetically induced absorption resonance in the Hanle configuration with a transverse magnetic field on a closed Fg ? Fe = Fg+1 transition with co-propagating orthogonal circularly polarized probe and coupling optical fields. At high coupling field intensities, the Hanle resonance changes sign due to a shift in atomic population from Zeeman sublevels associated with a probe field cyclic transition to sublevels associated with a coupling field cyclic transition at zero magnetic field. We also show that a similar sign reversal does not occur for ?-polarized and ?-polarized coupling fields.

Ram, Nibedita; Pattabiraman, M.

2010-12-01

287

Fatty acid oxidation is dispensable for human macrophage IL-4-induced polarization.  

PubMed

Macrophage polarization elicits various metabolic alterations which in turn influence the polarized phenotype. Activation of glycolytic metabolism accompanies and supports macrophage pro-inflammatory M1 polarization. In contrast, M2 polarization of murine macrophages in response to the Th2 cytokine interleukin-4 (IL-4) was linked to the up-regulation of mitochondrial oxidative metabolism and fatty acid oxidation (FAO), which was necessary for coining an IL-4-polarized phenotype. Here we investigated whether similar mechanisms operate in human macrophages stimulated with IL-4. IL-4 causes only moderate changes of mitochondrial oxidative metabolism and FAO, correlating with an unaltered expression of peroxisome proliferator-activated receptor-? coactivator 1 ?/? (PGC-1?/?), the master transcriptional regulators of mitochondrial biogenesis. Furthermore, attenuating FAO had no effect on IL-4-induced polarization-associated gene expression. Apparently, FAO is dispensable for IL-4-induced polarization of human macrophages, pointing to fundamental differences in the metabolic requirements of macrophage phenotype alterations between mice and humans. PMID:24960101

Namgaladze, Dmitry; Brüne, Bernhard

2014-09-01

288

Comparative study of electroabsorption in InGaN/GaN quantum zigzag heterostructures with polarization-induced electric fields  

E-print Network

with polarization-induced electric fields Emre Sari,1,2,3 Tuncay Ozel,2,3,4 Asli Koc,2,3 Jin-Woo Ju,5 Haeng-Keun Ahn is externally applied to compensate for the polarization-induced electric field across the wells, and theoretical analysis of InGaN/GaN quantum zigzag structures with different levels of polarization-induced

Demir, Hilmi Volkan

289

Light-Induced Polar pH Changes in Leaves of Elodea canadensis1  

PubMed Central

Leaves of the submerged aquatic Elodea canadensis Michx. exhibit a light induced polar pH reaction. In this study, the effects of light intensity and dissolved inorganic carbon concentration on this polar reaction were examined. At a light intensity of 100 watts per square meter the leaf showed a polar pH response when the dissolved inorganic carbon concentration was less than about 1 millimolar. The polar reaction was suppressed at a higher dissolved inorganic carbon concentration. This suppression was not due to the buffering capacity of bicarbonate. Because another weak acid, acetate, did not inhibit the polarity, but even had a small stimulatory effect, the effect of bicarbonate is also not due to acidification of the cytoplasm. The suppression of the polar reaction by CO2/HCO3? was relieved when the light intensity was increased. Apparently there is competition for product(s) of the photosynthetic light reactions between processes generating the polar reaction and the carbon fixation reactions. The possibility that the redox state of the cell regulates the generation of the polar reaction is discussed. PMID:16667044

Elzenga, J. Theo M.; Prins, Hidde B. A.

1989-01-01

290

Effects of polarization and p-type GaN resistivity on the spectral response of InGaN/GaN multiple quantum well solar cells  

NASA Astrophysics Data System (ADS)

Effects of polarization and p-type GaN resistivity on the spectral response of InGaN/GaN multiple quantum well (MQW) solar cells are investigated. It is found that due to the reduction of piezoelectric polarization and the enhancement of tunneling transport of photo-generated carriers in MQWs, the external quantum efficiency (EQE) of the solar cells increases in a low energy spectral range (? > 370 nm) when the barrier thickness value decreases from 15 nm to 7.5 nm. But the EQE decreases abruptly when the barrier thickness value decreases down to 3.75 nm. The reasons for these experimental results are analyzed. We are aware that the reduction of depletion width in MQW region, caused by the high resistivity of the p-type GaN layer may be the main reason for the abnormally low EQE value at long wavelengths (? > 370 nm).

Yang, Jing; Zhao, De-Gang; Jiang, De-Sheng; Liu, Zong-Shun; Chen, Ping; Li, Liang; Wu, Liang-Liang; Le, Ling-Cong; Li, Xiao-Jing; He, Xiao-Guang; Wang, Hui; Zhu, Jian-Jun; Zhang, Shu-Ming; Zhang, Bao-Shun; Yang, Hui

2014-06-01

291

Contact-induced spin polarization in BNNT(CNT)/TM (TM=Co, Ni) nanocomposites  

NASA Astrophysics Data System (ADS)

The interaction between carbon and BN nanotubes (NT) and transition metal Co and Ni supports was studied using electronic structure calculations. Several configurations of interfaces were considered, and the most stable ones were used for electronic structure analysis. All NT/Co interfaces were found to be more energetically favorable than NT/Ni, and conductive carbon nanotubes demonstrate slightly stronger bonding than semiconducting ones. The presence of contact-induced spin polarization was established for all nanocomposites. It was found that the contact-induced polarization of BNNT leads to the appearance of local conductivity in the vicinity of the interface while the rest of the nanotube lattice remains to be insulating.

Kuzubov, Alexander A.; Kovaleva, Evgenia A.; Avramov, Paul; Kuklin, Artem V.; Mikhaleva, Natalya S.; Tomilin, Felix N.; Sakai, Seiji; Entani, Shiro; Matsumoto, Yoshihiro; Naramoto, Hiroshi

2014-08-01

292

Light-induced polarization effects in atoms with partially resolved hyperfine structure and applications to absorption, fluorescence, and nonlinear magneto-optical rotation  

E-print Network

Light-induced polarization effects in atoms with partially resolved hyperfine structure polarization by atoms in a polarized state can be reduced electromagnetically induced transparency 3 or in involving magnetic-field-induced evolution of long-lived ground-state polarization--can be used to perform

Auzinsh, Marcis

293

Alignment and orientation of diatomic molecules induced by polarized electron impact This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Alignment and orientation of diatomic molecules induced by polarized electron impact This article induced by polarized electron impact J W Maseberg and T J Gay Behlen Laboratory of Physics, University induced by spin-polarized electron impact. Circular polarizations resulting from some Fulcher- transitions

Gay, Timothy J.

294

Edge-Induced Qubit Polarization in Systems with Ising Anyons  

E-print Network

We investigate the proposed experimental setup for measuring the topological charge in a an Ising anyon system by means of Fabry-P\\'erot interferometry with a chiral edge state. We show that such an interferometer has the unintended but not necessarily unwelcome effect of stabilizing the state of the system being measured (i.e., a topological qubit). We show further that interactions between the edge mode and the localized bulk quasiparticles can have the effect of polarizing the qubit, stabilizing its state. We discuss the these results in the context of recent interferometer experiments in the 5/2 fractional quantum Hall state, where the first of these effects is small, but the second may be relevant to the observed phenomena.

David J Clarke; Kirill Shtengel

2011-02-10

295

Observations of a distinctive infra-red spectral feature in the atmospheric spectra of polar stratospheric clouds measured by the CRISTA instrument  

NASA Astrophysics Data System (ADS)

Polar stratospheric cloud particles (PSCs) are known to strongly influence the infra-red emission spectrum of the lower stratosphere in cold polar winters. The characteristics of these infra-red features have been examined using limb sounding spectra recorded by the CRISTA experiment in August 1997 when many Antarctic PSCs were observed. A distinctive spectral feature centered at 820 cm-1 has been identified in many of these spectra, the first time that a particular band has been observed in the spectra of PSCs in the atmosphere. The feature can be attributed to the ?2 band of the NO3- ion and strongly suggests a condensed nitric acid component to the particles in the form of solid nitric acid trihydrate (NAT) or liquid ternary solution (STS). The spectral signatures belong to a definite sub-set of the PSC observations recorded by CRISTA. The particles are observed at temperatures well above 192 K, allowing for temperature errors, and it is suggested that NAT particles are the most likely source of the spectral signature. In addition, it is shown that PSC events in which no spectral signature is present are only observed below 192 K and display a very similar HNO3-temperature relationship to STS particles.

Spang, Reinhold; Remedios, John J.

2003-08-01

296

Measurement of the Induced Polarization of {Lambda}(1116) in Kaon Electroproduction with CLAS  

SciTech Connect

The CLAS Collaboration is using the p(e, e'K{sup +}p){pi}{sup -} reaction to measure the induced polarization of the electroproduced {Lambda}(1116). In this experiment a 5.499-GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The CEBAF Large Acceptance Spectrometer (CLAS) was used to detect the scattered electron, the kaon, and the decay proton from the {Lambda} hyperon. CLAS allowed for a large kinematic acceptance in Q{sup 2}(0.75{<=}Q{sup 2{<=}}3.5 GeV{sup 2}) and W(1.6{<=}W{<=}3.0 GeV), as well as the kaon center-of-mass scattering angle. The goal is to map out the kinematic dependencies for the induced polarization in order to provide new constraints on models of K-hyperon production. Along with previously published photo- and electroproduction cross sections and polarization observables from CLAS, LEPS, SAPHIR, and GRAAL, these new induced polarization data are needed in coupled-channel analyses to search for previously unobserved s-channel resonances. Preliminary polarization results are presented.

Gabrielyan, Marianna; Raue, Brian; Dhamija, Seema [Florida International University, Miami, FL 33199 (United States); Carman, Daniel S. [Jefferson Laboratory, Newport News, VA 23606 (United States)

2010-08-05

297

Measurement of the Induced Polarization of Lambda (1116) in Kaon Electroproduction with CLAS  

SciTech Connect

The CLAS Collaboration is using the p(e,e[prime]K+p)pi? reaction to measure the induced polarization of the electroproduced Lambda(1116). In this experiment a 5.499-GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The CEBAF Large Acceptance Spectrometer (CLAS) was used to detect the scattered electron, the kaon, and the decay proton from the Lambda hyperon. CLAS allowed for a large kinematic acceptance in Q2(0.75<=Q2<=3.5 GeV2) and W(1.6<=W<=3.0 GeV), as well as the kaon center-of-mass scattering angle. The goal is to map out the kinematic dependencies for the induced polarization in order to provide new constraints on models of K-hyperon production. Along with previously published photo- and electroproduction cross sections and polarization observables from CLAS, LEPS, SAPHIR, and GRAAL, these new induced polarization data are needed in coupled-channel analyses to search for previously unobserved s-channel resonances. Preliminary polarization results are presented.

Marianna Gabrielyan, Brian Raue, Seema Dhamija, Daniel S. Carman

2010-08-01

298

Microwave polarization in the direction of galaxy clusters induced by the CMB quadrupole anisotropy  

E-print Network

Electron scattering induces a polarization in the cosmic microwave background (CMB) signal measured in the direction of a galaxy cluster due to the presence of a quadrupole component in the CMB temperature distribution. Measuring the polarization towards distant clusters provides the unique opportunity to observe the evolution of the CMB quadrupole at moderate redshifts, z~0.5-3. We demonstrate that for the local cluster population the polarization degree will depend on the cluster celestial position. There are two extended regions in the sky, which are opposite to each other, where the polarization is maximal, 0.1(tau/0.02) microK in the Rayleigh-Jeans part of the CMB spectrum (tau being the Thomson optical depth across the cluster) exceeding the contribution from the cluster transverse peculiar motion if v_tpolarization components produced in clusters. These polarization effects, which are of the order of (v_t/c)^2 tau, (v_t/c) tau^2 and (kT_e/m_ec^2) tau^2, as well as the polarization due to the CMB quadrupole, were previously calculated by Sunyaev and Zel'dovich for the Rayleigh-Jeans region. We fully confirm their earlier results and present exact frequency dependencies for all these effects. The polarization is considerably higher in the Wien region of the CMB spectrum.

S. Y. Sazonov; R. A. Sunyaev

1999-03-18

299

Magnetic-field-induced ferroelectric polarization reversal in magnetoelectric composites revealed by piezoresponse force microscopy  

NASA Astrophysics Data System (ADS)

Controlling electric polarization (or magnetization) in multiferroic materials with external magnetic fields (or electric fields) is very important for fundamental physics and spintronic devices. Although there has been some progress on magnetic-field-induced polarization reversal in single-phase multiferroics, such behavior has so far never been realized in composites. Here we show that it is possible to reverse ferroelectric polarization using magnetic fields in a bilayer Terfenol-D/PMN-33%PT composite. We realized this by ferroelectric domain imaging using piezoresponse force microscopy (PFM) under applied magnetic field loading. The internal electric field caused by the magnetoelectric (ME) effect in the PMN-PT crystal is considered as the driving force for the 180° polarization switching, and its existence is verified by switching spectroscopy PFM testing under a series of external magnetic fields. A quantitative method is further suggested to estimate the local ME coefficient based on the switching spectroscopy PFM testing results.

Miao, Hongchen; Zhou, Xilong; Dong, Shuxiang; Luo, Haosu; Li, Faxin

2014-07-01

300

Strain-gradient-induced polarization in SrTiO3 single crystals.  

PubMed

Piezoelectricity is inherent only in noncentrosymmetric materials, but a piezoelectric response can also be obtained in centrosymmetric crystals if subjected to inhomogeneous deformation. This phenomenon, known as flexoelectricity, can significantly affect the functional properties of insulators, particularly thin films of high permittivity materials. We have measured strain-gradient-induced polarization in single crystals of paraelectric SrTiO3 as a function of temperature and orientation down to and below the 105 K phase transition. Estimates were obtained for all the components of the flexoelectric tensor, and calculations based on these indicate that local polarization around defects in SrTiO3 may exceed the largest ferroelectric polarizations. A sign reversal of the flexoelectric response detected below the phase transition suggests that the ferroelastic domain walls of SrTiO3 may be polar. PMID:17995293

Zubko, P; Catalan, G; Buckley, A; Welche, P R L; Scott, J F

2007-10-19

301

Blue-light-induced PIN3 polarization for root negative phototropic response in Arabidopsis.  

PubMed

Root negative phototropism is an important response in plants. Although blue light is known to mediate this response, the cellular and molecular mechanisms underlying root negative phototropism remain unclear. Here, we report that the auxin efflux carrier PIN-FORMED (PIN) 3 is involved in asymmetric auxin distribution and root negative phototropism. Unilateral blue-light illumination polarized PIN3 to the outer lateral membrane of columella cells at the illuminated root side, and increased auxin activity at the illuminated side of roots, where auxin promotes growth and causes roots bending away from the light source. Furthermore, root negative phototropic response and blue-light-induced PIN3 polarization were modulated by a brefeldin A-sensitive, GNOM-dependent, trafficking pathway and by phot1-regulated PINOID (PID)/PROTEIN PHOSPHATASE 2A (PP2A) activity. Our results indicate that blue-light-induced PIN3 polarization is needed for asymmetric auxin distribution during root negative phototropic response. PMID:23888933

Zhang, Kun-Xiao; Xu, Heng-Hao; Yuan, Ting-Ting; Zhang, Liang; Lu, Ying-Tang

2013-10-01

302

The effects of tidally induced disc structure on white dwarf accretion in intermediate polars  

E-print Network

We investigate the effects of tidally induced asymmetric disc structure on accretion onto the white dwarf in intermediate polars. Using numerical simulation, we show that it is possible for tidally induced spiral waves to propagate sufficiently far into the disc of an intermediate polar that accretion onto the central white dwarf could be modulated as a result. We suggest that accretion from the resulting asymmetric inner disc may contribute to the observed X-ray and optical periodicities in the light curves of these systems. In contrast to the stream-fed accretion model for these periodicities, the tidal picture predicts that modulation can exist even for systems with weaker magnetic fields where the magnetospheric radius is smaller than the radius of periastron of the mass transfer stream. We also predict that additional periodic components should exist in the emission from low mass ratio intermediate polars displaying superhumps.

J. R. Murray; P. J. Armitage; L. Ferrario; D. T Wickramasinghe

1998-09-10

303

Magnetization and phase transition induced by circularly polarized laser in quantum magnets  

NASA Astrophysics Data System (ADS)

We theoretically predict a nonequilibrium phase transition in quantum spin systems induced by a laser, which provides a purely quantum-mechanical way of coherently controlling magnetization. Namely, when a circularly polarized laser is applied to a spin system, the magnetic component of a laser is shown to induce a magnetization normal to the plane of polarization, leading to an ultrafast phase transition. We first demonstrate this phenomenon numerically for an S =1 antiferromagnetic Heisenberg spin chain, where a new state emerges with magnetization perpendicular to the polarization plane of the laser in place of the topologically ordered Haldane state. We then elucidate its physical mechanism by mapping the system to an effective static model. The theory also indicates that the phenomenon should occur in general quantum spin systems with a magnetic anisotropy. The required laser frequency is in the terahertz range, with the required intensity being within a prospective experimental feasibility.

Takayoshi, Shintaro; Aoki, Hideo; Oka, Takashi

2014-08-01

304

Electric-field induced capillary interaction of charged particles at a polar interface  

E-print Network

We study the electric-field induced capillary interaction of charged particles at a polar interface. The algebraic tails of the electrostatic pressure of each charge results in a deformation of the interface $u\\sim \\rho ^{-4}$. The resulting capillary interaction is repulsive and varies as $\\rho ^{-6}$ with the particle distance. As a consequence, electric-field induced capillary forces cannot be at the origin of the secondary minimum observed recently for charged PMMA particles at on oil-water interface.

Lionel Foret; Alois Würger

2003-10-28

305

Field-induced polarization of Dirac valleys in bismuth  

NASA Astrophysics Data System (ADS)

The principal challenge in the field of ``valleytronics'' is to lift the valley degeneracy of electrons in a controlled way. In graphene, a number of methods to generate a valley-polarized flow of electrons have been proposed, which are yet to be experimentally realized. In bulk semi-metallic bismuth, the Fermi surface includes three cigar-shaped electron valleys lying almost perpendicular to the high-symmetry axis known as the trigonal axis. The in-plane mass anisotropy of each valley exceeds 200 as a consequence of Dirac dispersion, which drastically reduces the effective mass along two out of the three orientations. We present a study of angle-dependent magnetoresistance in bismuth which shows that a flow of Dirac electrons along the trigonal axis is extremely sensitive to the orientation of in-plane magnetic field. The effect is visible even at room temperature. Thus, a rotatable magnetic field can be used as a valley valve to tune the contribution of each valley to the total conductivity. At high temperature and low magnetic field, the three valleys are interchangeable and the three-fold symmetry of the underlying lattice is respected. As the temperature is decreased or the magnetic field increased, this symmetry is spontaneously lost. This loss may be an experimental manifestation of the recently proposed valley-nematic Fermi liquid state.

Behnia, Kamran; Zhu, Zengwei; Callaudin, Aurelie; Fauque, Benoit; Kang, Woun

2012-02-01

306

Induced-Polarization Measurements at Roosevelt Hot Springs Thermal Area, Utah.  

National Technical Information Service (NTIS)

An induced polarization survey was conducted at Roosevelt Hot Springs, using the dipole-dipole array. The survey consisted of two profile lines, one across the southern end of the system (2200N) and another across the northern portion (5950N). A total of ...

J. J. Chu, W. R. Sill, S. H. Ward

1979-01-01

307

Inversion of two-dimensional resistivity and induced-polarization data  

Microsoft Academic Search

A fast ridge regression inversion technique was devised for the interpretation of simple two-dimensional resistivity and induced-polarization data. The program will determine the rectangular source under a single layer of overburden which best fits the observed data. Unfortunately, each ridge regression inversion requires a great many forward problem evaluations. One method to reduce the calculation time is to store in

W. H. Pelton; L. Rijo; C. M. Jr. Swift

1978-01-01

308

Tensor-Induced CMB Temperature-Polarization Correlation in Reionized Universes  

E-print Network

We reexamine the temperature-polarization correlation function of the cosmic microwave background induced by tensor mode with a scale-invariant spectrum in reionized standard cold dark matter models. It is found that the sign of the correlation function is positive on all angular scales even in a model with substantial reionization.

Kin-Wang Ng

1999-05-04

309

Multi-array borehole resistivity and induced polarization method with mathematical inversion of redundant data  

DOEpatents

Multiple arrays of electric or magnetic transmitters and receivers are used in a borehole geophysical procedure to obtain a multiplicity of redundant data suitable for processing into a resistivity or induced polarization model of a subsurface region of the earth. 30 figs.

Ward, S.H.

1989-10-17

310

Resistivity and induced polarization monitoring of salt transport under natural hydraulic gradients  

Microsoft Academic Search

The authors demonstrate the use of resistivity\\/induced polarization (IP) monitoring of salt transport under natural hydraulic loads. Electrical monitoring of saline tracer transport during forced injection has been demonstrated previously. Detection of tracer transport under natural hydraulic loading is difficult because neither the hydraulic load nor the tracer resistivity can be controlled. In one study, the authors identify the electrical

Lee D. Slater; Stewart K. Sandberg

2000-01-01

311

Relativistic Calculations of Induced Polarization in $^{12}C$(e, e' \\vec{p})$ Reactions  

E-print Network

Relativistic calculations of the induced proton polarization in quasifree electron scattering on $^{12}C$ are presented. Good agreement with the experimental data of Woo et al. is obtained. The relativistic calculations yield a somewhat better description of the data than the non-relativistic ones. Differences between the two approaches are more pronounced at larger missing momenta suggesting further experimental work in this region.

J. I. Johansson; H. S. Sherif

1999-05-06

312

Relativistic calculations of induced polarization in 12C(e,e'p-->) reactions  

NASA Astrophysics Data System (ADS)

Relativistic calculations of the induced proton polarization in quasifree electron scattering on 12C are presented. Good agreement with the experimental data of Woo et al. is obtained. The relativistic calculations yield a somewhat better description of the data than the nonrelativistic ones. Differences between the two approaches are more pronounced at larger missing momenta suggesting further experimental work in this region.

Johansson, J. I.; Sherif, H. S.

1999-06-01

313

3-D inversion of induced polarization data in wavelet domain and Yaoguo Li, Department of Geophysics, Colorado School of Mines  

E-print Network

3-D inversion of induced polarization data in wavelet domain Yaping Zhu and Yaoguo Li, Department practical application to large field data sets. Introduction Inferring mineral deposits based on induced polarization (IP) data has evolved from qualitative interpretation of pseudosections to inversion of 2-D and 3

314

J. Non-Newtonian Fluid Mech. 134 (2006) 3343 Flow-induced anisotropy in polar ice and related  

E-print Network

J. Non-Newtonian Fluid Mech. 134 (2006) 33­43 Flow-induced anisotropy in polar ice and related ice that gives the distribution of the orientation of all the constituents (grains). This paper presents a strain-induced bed is studied. © 2005 Elsevier B.V. All rights reserved. Keywords: Polar ice anisotropy; Ice

Gagliardini, Olivier

315

IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 18, NO. 12, JUNE 15, 2006 1365 Source-Induced Optical Noise in Polarization  

E-print Network

, polarization-mode dispersion (PMD), statistical optics. I. INTRODUCTION SOURCE-INDUCED optical noise may becomeIEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 18, NO. 12, JUNE 15, 2006 1365 Source-Induced Optical Noise in Polarization Measurements Avi Zadok and Avishay Eyal, Member, IEEE Abstract--Formalism is derived

Zadok, Avinoam

316

Polarization-Induced Charge Distribution at Homogeneous Zincblende/Wurtzite Heterostructural Junctions in ZnSe Nanobelts  

SciTech Connect

Homogeneous heterostructural wurtzite (WZ)/zincblende (ZB) junctions are successfully fabricated in ZnSe nanobelts. Polarity continuity across the ZB/WZ interface is demonstrated. The saw-tooth-like potential profile induced by spontaneous polarization across the WZ/ZB/WZ interfaces is identified directly at the nanoscale. The polarization-induced charge distribution across the homogeneous heterostructural interfaces is proposed as a viable alternative approach towards charge tailoring in semiconductor nanostructures.

Li, L.; Jin, L.; Wang, J.; Smith, D. J.; Yin, W. J.; Yan, Y.; Sang, H.; Choy, W. C. H.; McCartney, M. R.

2012-03-08

317

Polar correlations and defect-induced ferroelectricity in cryogenic KTaO3  

NASA Astrophysics Data System (ADS)

KTaO3 is an incipient ferroelectric material with an extrapolated transition temperature below 0 K. It contains a small number of "unavoidable defects" which are randomly distributed. Some of these defects are polar and their interaction leads to macroscopic coherent polar structures at low temperatures. In this article it is shown that freezing of local defect dipoles coincides with elastic stiffening and damping of ultrasonic waves in KTaO3. The elastic freezing anomalies are accompanied by stepwise increases of piezoelectricity, forming a thermal polar staircase below ca. 120 K and a gigantic enhancement below 50 K. A small spontaneous polarization also emerges below this temperature, gradually increasing to a value of 0.045 ? C cm -2 at 5 K with increasing coherency of defect dipoles. The orientation of this spontaneous polarization depends on a weak strain-induced anisotropy of the macroscopic sample. Defect-induced ferroelectricity, as demonstrated for KTaO3, may be a possible way forward to develop functional device materials based on the switching of coherently interacting defects.

Aktas, Oktay; Crossley, Sam; Carpenter, Michael A.; Salje, Ekhard K. H.

2014-10-01

318

Surface-induced heating of cold polar molecules  

E-print Network

We study the rotational and vibrational heating of diatomic molecules placed near a surface at finite temperature on the basis of macroscopic quantum electrodynamics. The internal molecular evolution is governed by transition rates that depend on both temperature and position. Analytical and numerical methods are used to investigate the heating of several relevant molecules near various surfaces. We determine the critical distances at which the surface itself becomes the dominant source of heating and we investigate the transition between the long-range and short-range behaviour of the heating rates. A simple formula is presented that can be used to estimate the surface-induced heating rates of other molecules of interest. We also consider how the heating depends on the thickness and composition of the surface.

Stefan Yoshi Buhmann; M. R. Tarbutt; Stefan Scheel; E. A. Hinds

2008-06-18

319

Dual-band wavelength tunable nonlinear polarization rotation mode-locked Erbium-doped fiber lasers induced by birefringence variation and gain curvature alteration.  

PubMed

With the combining effects of the fiber birefringence induced round-trip phase variation and the gain profile reshaping induced spectral filtering in the Erbium-doped fiber laser (EDFL) cavity, the mechanism corresponding to the central wavelength tunability of the EDFL passively mode-locked by nonlinear polarization rotation is explored. Bending the intracavity fiber induces the refractive index difference between orthogonal axes, which enables the dual-band central wavelength shift of 2.9 nm at 1570 nm region and up to 10.2 nm at 1600 nm region. The difference between the wavelength shifts at two bands is attributed to the gain dispersion decided by the gain spectral curvature of the EDFA, and the spacing between two switchable bands is provided by the birefringence induced variation on phase delay which causes transmittance variation. In addition, the central wavelength shift can also be controlled by varying the pumping geometry. At 1570 nm regime, an offset of up to 5.9 nm between the central wavelengths obtained under solely forward or backward pumping condition is observed, whereas the bidirectional pumping scheme effectively compensates the gain spectral reshaping effects to minimize the central wavelength shift. In contrast, the wavelength offset shrinks to only 1.1 nm when mode-locking at 1600 nm under single-sided pumping, as the gain profile strongly depends on the spatial distribution of the excited erbium ions under different pumping schemes. Except the birefringence variation and the gain spectral filtering phenomena, the gain-saturation mechanism induced refractive index change and its influence to the dual-band central wavelength tunability are also observed and analyzed. PMID:25321587

Lin, Sheng-Fong; Lin, Gong-Ru

2014-09-01

320

Polarized and unpolarized $?$-pair meson-induced Drell--Yan production and the pion distribution amplitude  

E-print Network

We present a detailed analysis of meson-induced massive lepton (muon) Drell--Yan production for the process $\\pi^{-}N\\to\\mu^{+}\\mu^{-}X$, considering both an unpolarized nucleon target and longitudinally polarized protons. Using a QCD framework, we focus on the angular distribution of $\\mu^+$, which is sensitive to the shape of the pion distribution amplitude, the goal being to test corresponding results against available experimental data. Predictions are made, employing various pion distribution amplitudes, for the azimuthal angle dependence of the $\\mu^{+}$ distribution in the polarized case, relevant for the planned COMPASS experiment. QCD evolution is given particular attention in both considered cases.

A. P. Bakulev; N. G. Stefanis; O. V. Teryaev

2007-06-28

321

Multi-spectral plasmon induced transparency via in-plane dipole and dual-quadrupole coupling.  

PubMed

We experimentally demonstrated an approach based on dipole and dual-quadrupole coupling to construct a planar metamaterial supporting multi-spectral plasmon induced transparency. The structure consists of two short silver wires (dipole) and two long silver wires (dual-quadrupole). The in-plane coupling between the dipole and the dual-quadrupole leads to two transmission windows even in the absorbance linewidth of the dipole. This phenomenon is well described and understood by numerical analyses and a classical oscillator model. PMID:24921261

Miyata, Masashi; Hirohata, Jumpei; Nagasaki, Yusuke; Takahara, Junichi

2014-05-19

322

Spectral analysis of photo-induced delayed luminescence from human skin in vivo  

NASA Astrophysics Data System (ADS)

The UVA induced Delayed Luminescence (DL), has been measured in vivo in the forearm skin of some healthy volunteers of different sex and age during several periods of the year. An innovative instrument able to detect, in single photon counting mode, the spectrum and the time trend of the DL emission has been used. The measured differences in the time trends of the spectral components may be related to the sex and the age. The potential development of a new analysis technique based on this phenomenon is discussed.

Musumeci, Francesco; Lanzanò, Luca; Privitera, Simona; Tudisco, Salvatore; Scordino, Agata

2007-07-01

323

Parahydrogen-induced polarization at zero magnetic field.  

PubMed

We use symmetry arguments and simple model systems to describe the conversion of the singlet state of parahydrogen into an oscillating sample magnetization at zero magnetic field. During an initial period of free evolution governed by the scalar-coupling Hamiltonian HJ, the singlet state is converted into scalar spin order involving spins throughout the molecule. A short dc pulse along the z axis rotates the transverse spin components of nuclear species I and S through different angles, converting a portion of the scalar order into vector order. The development of vector order can be described analytically by means of single-transition operators, and it is found to be maximal when the transverse components of I are rotated by an angle of ±??2 relative to those of S. A period of free evolution follows the pulse, during which the vector order evolves as a set of oscillating coherences. The imaginary parts of the coherences represent spin order that is not directly detectable, while the real parts can be identified with oscillations in the z component of the molecular spin dipole. The dipole oscillations are due to a periodic exchange between Iz and Sz, which have different gyromagnetic ratios. The frequency components of the resulting spectrum are imaginary, since the pulse cannot directly induce magnetization in the sample; it is only during the evolution under HJ that the vector order present at the end of the pulse evolves into detectable magnetization. PMID:23802953

Butler, Mark C; Kervern, Gwendal; Theis, Thomas; Ledbetter, Micah P; Ganssle, Paul J; Blanchard, John W; Budker, Dmitry; Pines, Alexander

2013-06-21

324

Modeling and inversion Matlab algorithms for resistivity, induced polarization and seismic data  

NASA Astrophysics Data System (ADS)

M. Karaoulis (1), D.D. Werkema (3), A. Revil (1,2), A., B. Minsley (4), (1) Colorado School of Mines, Dept. of Geophysics, Golden, CO, USA. (2) ISTerre, CNRS, UMR 5559, Université de Savoie, Equipe Volcan, Le Bourget du Lac, France. (3) U.S. EPA, ORD, NERL, ESD, CMB, Las Vegas, Nevada, USA . (4) USGS, Federal Center, Lakewood, 10, 80225-0046, CO. Abstract We propose 2D and 3D forward modeling and inversion package for DC resistivity, time domain induced polarization (IP), frequency-domain IP, and seismic refraction data. For the resistivity and IP case, discretization is based on rectangular cells, where each cell has as unknown resistivity in the case of DC modelling, resistivity and chargeability in the time domain IP modelling, and complex resistivity in the spectral IP modelling. The governing partial-differential equations are solved with the finite element method, which can be applied to both real and complex variables that are solved for. For the seismic case, forward modeling is based on solving the eikonal equation using a second-order fast marching method. The wavepaths are materialized by Fresnel volumes rather than by conventional rays. This approach accounts for complicated velocity models and is advantageous because it considers frequency effects on the velocity resolution. The inversion can accommodate data at a single time step, or as a time-lapse dataset if the geophysical data are gathered for monitoring purposes. The aim of time-lapse inversion is to find the change in the velocities or resistivities of each model cell as a function of time. Different time-lapse algorithms can be applied such as independent inversion, difference inversion, 4D inversion, and 4D active time constraint inversion. The forward algorithms are benchmarked against analytical solutions and inversion results are compared with existing ones. The algorithms are packaged as Matlab codes with a simple Graphical User Interface. Although the code is parallelized for multi-core cpus, it is not as fast as machine code. In the case of large datasets, someone should consider transferring parts of the code to C or Fortran through mex files. This code is available through EPA's website on the following link http://www.epa.gov/esd/cmb/GeophysicsWebsite/index.html Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy.

Karaoulis, M.; Revil, A.; Minsley, B. J.; Werkema, D. D.

2011-12-01

325

Polarization and collision-induced coherence in the beam-foil light source  

NASA Technical Reports Server (NTRS)

Monatomic systems were excited by the beam-foil method in order to re-examine the possibility that a particular magnetic substate was preferentially populated. O II, Ar II and He I levels were used. The results reveal that: (1) with a tilted foil substantial polarization (up to 15%) may be achieved, (2) the polarization is due to the foil, (3) the foil induces coherence among Zeeman substates with the appearance of quantum beats among these substates and that their coherence is due to the externally applied magnetic field perpendicular to the beam direction, and (4) the angular momentum of the emitted photon is perpendicular to the ion velocity. The possibility for detecting separate effects of alignment and polarization is noted.

Liu, C. H.; Bashkin, S.; Church, D. A.

1974-01-01

326

Multilayer Thin Film Polarizer Design for Far Ultraviolet using Induced Transmission and Absorption Technique  

NASA Technical Reports Server (NTRS)

Good theoretical designs of far ultraviolet polarizers have been reported using a MgF2/Al/MgF2 three layer structure on a thick Al layer as a substrate. The thicknesses were determined to induce transmission and absorption of p-polarized light. In these designs Al optical constants were used from films produced in ultrahigh vacuum (UHV: 10(exp -10) torr). Reflectance values for polarizers fabricated in a conventional high vacuum (p approx. 10(exp -6 torr)) using the UHV design parameters differed dramatically from the design predictions. Al is a highly reactive material and is oxidized even in a high vacuum chamber. In order to solve the problem other metals have been studied. It is found that a larger reflectance difference is closely related to higher amplitude and larger phase difference of Fresnel reflection coefficients between two polarizations at the boundary of MgF2/metal. It is also found that for one material a larger angle of incidence from the surface normal brings larger amplitude and phase difference. Be and Mo are found good materials to replace Al. Polarizers designed for 121.6 nm with Be at 60 deg and with Mo at 70 deg are shown as examples.

Kim, Jongmin; Zukic, Muamer; Wilson, Michele M.; Park, Jung Ho; Torr, Douglas G.

1994-01-01

327

Spectral Induced Polarization (SIP) monitoring during Microbial Enhanced Oil Recovery (MEOR)  

Microsoft Academic Search

Jeffrey Heenan, Dimitrios Ntarlagiannis, Lee Slater Department of Earth and Environmental Sciences, Rutgers University, Newark NJ Microbial Enhanced Oil Recovery (MEOR) is an established, cost effective, method for enhancing tertiary oil recovery. Although not commonly used for shallow heavy oils, it could be a viable alternative since it can offer sustainable economic recovery and minimal environmental impact. A critical component

J. W. Heenan; D. Ntarlagiannis; L. D. Slater

2010-01-01

328

Giant Ferroelectric Polarization of CaMn7O12 Induced by a Combined Effect of Dzyaloshinskii-Moriya Interaction and Exchange Striction  

E-print Network

Giant Ferroelectric Polarization of CaMn7O12 Induced by a Combined Effect of Dzyaloshinskii induce a nonzero ferroelectric polarization. Recently, we presented a more general model [12] that explains the ferroelectric polarizations induced by a helical magnetic structure. These ferroelectric

Gong, Xingao

329

Surface polar states and pyroelectricity in ferroelastics induced by flexo-A. N. Morozovska, E. A. Eliseev, S. V. Kalinin, Long Qing Chen, and Venkatraman Gopalan  

E-print Network

Surface polar states and pyroelectricity in ferroelastics induced by flexo- roto field A. N://apl.aip.org/about/rights_and_permissions #12;Surface polar states and pyroelectricity in ferroelastics induced by flexo-roto field A. N rotations, and thus, it can induce surface polar states and pyroelectricity in a large class of otherwise

Chen, Long-Qing

330

B-mode polarization induced by gravitational waves from kinks on infinite cosmic strings  

E-print Network

We investigate the effect of the stochastic gravitational wave (GW) background produced by kinks on infinite cosmic strings, whose spectrum was derived in our previous work, on the B-mode power spectrum of the cosmic microwave background (CMB) anisotropy. We find that the B-mode polarization due to kinks is comparable to that induced by the motion of the string network and hence the contribution of GWs from kinks is important for estimating the B-mode power spectrum originating from cosmic strings. If the tension of cosmic strings \\mu is large enough i.e., G\\mu >~ 10^{-8}, B-mode polarization induced by cosmic strings can be detected by future CMB experiments.

Masahiro Kawasaki; Koichi Miyamoto; Kazunori Nakayama

2010-03-19

331

Induced Polarization in the $^2$H($?,\\vec n$)$^1$H Reaction at Low Energy  

E-print Network

The induced polarization, $P^\\prime_y$, of the neutron in the deuteron photo-disintegration from threshold up to 30 MeV is calculated using a variety of different, latest-generation potentials--Argonne $v_{18}$, Bonn 2000, and Nijmegen I-- and a realistic model for the nuclear electromagnetic current operator, including one- and two-body terms. The model dependence of the theoretical predictions is found to be very small. These predictions are systematically larger in magnitude than the measured $P^\\prime_y$ values, and corroborate the conclusions of an earlier, and much older, study. There is considerable scatter in the available experimental data. New and more accurate measurements of the induced polarization in the $^2$H($\\gamma,\\vec n$)$^1$H reaction are needed in order to establish unequivocally whether there is a discrepancy between theory and experiment.

R. Schiavilla

2005-05-25

332

B-mode polarization induced by gravitational waves from kinks on infinite cosmic strings  

SciTech Connect

We investigate the effect of the stochastic gravitational wave (GW) background produced by kinks on infinite cosmic strings, whose spectrum was derived in our previous work, on the B-mode power spectrum of the cosmic microwave background (CMB) anisotropy. We find that the B-mode polarization due to kinks is comparable to that induced by the motion of the string network and hence the contribution of GWs from kinks is important for estimating the B-mode power spectrum originating from cosmic strings. If the tension of cosmic strings {mu} is large enough, i.e., G{mu} > or approx. 10{sup -8}, B-mode polarization induced by cosmic strings can be detected by future CMB experiments.

Kawasaki, Masahiro [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan); Miyamoto, Koichi [Institute for Cosmic Ray Research, University of Tokyo, Kashiwa, Chiba 277-8582 (Japan); Nakayama, Kazunori [KEK Theory Center, Institute of Particle and Nuclear Studies, KEK, Tsukuba, Ibaraki 305-0801 (Japan)

2010-11-15

333

Light Induced Polarity of Redox Reactions in Leaves of Elodea canadensis Michx 1  

PubMed Central

This paper reports that extracellular reductase activity in leaves of Elodea canadensis, hitherto never associated with polar processes thought to be involved in bicarbonate utilization, also shows a very marked polarity in light. The effect of ferricyanide, applied to the lower side of illuminated leaves, was a depolarization of the membrane electrical potential of up to 110 millivolts, while no depolarization was induced when ferricyanide was applied to the upper side. In the dark ferricyanide induced a depolarization when applied to either the upper or to the lower side of the leaf. Staining with tetrazolium salts, specific indicators for reductase activity, resulted in the formation of a precipitate on the lower side of the leaf when illuminated and on both sides in the dark. The precipitate was only located along the plasmalemma. Images Fig. 1 Fig. 2 PMID:16665663

Elzenga, J. Theo M.; Prins, Hidde B. A.

1987-01-01

334

Induced Polarization in the 2H(gamma,n)p Reaction at Low Energy  

SciTech Connect

The induced polarization, P{prime}{sub y}, of the neutron in the deuteron photo-disintegration from threshold up to 30 MeV is calculated using a variety of different, latest-generation potentials--Argonne v{sub 18}, Bonn 2000, and Nijmegen I--and a realistic model for the nuclear electromagnetic current operator, including one- and two-body terms. The model dependence of the theoretical predictions is found to be very small. These predictions are systematically larger in magnitude than the measured P{prime}{sub y} values, and corroborate the conclusions of an earlier, and much older, study. There is considerable scatter in the available experimental data. New and more accurate measurements of the induced polarization in the {sup 2}H({gamma},{rvec n}){sup 1}H reaction are needed in order to establish unequivocally whether there is a discrepancy between theory and experiment.

Rocco Schiavilla

2005-05-01

335

Horizontal polarization of ground motion in the Hayward fault zone at Fremont, California: dominant fault-high-angle polarization and fault-induced cracks  

NASA Astrophysics Data System (ADS)

We investigate shear wave polarization in the Hayward fault zone near Niles Canyon, Fremont, CA. Waveforms of 12 earthquakes recorded by a seven-accelerometer seismic array around the fault are analysed to clarify directional site effects in the fault damage zone. The analysis is performed in the frequency domain through H/V spectral ratios with horizontal components rotated from 0° to 180°, and in the time domain using the eigenvectors and eigenvalues of the covariance matrix method employing three component records. The near-fault ground motion tends to be polarized in the horizontal plane. At two on-fault stations where the local strike is N160°, ground motion polarization is oriented N88 ± 19° and N83 ± 32°, respectively. At a third on-fault station, the motion is more complex with horizontal polarization varying in different frequency bands. However, a polarization of N86 ± 7°, similar to the results at the other two on-fault stations, is found in the frequency band 6-8 Hz. The predominantly high-angle polarization from the fault strike at the Hayward Fault is consistent with similar results at the Parkfield section of the San Andreas Fault and the Val d'Agri area (a Quaternary extensional basin) in Italy. In all these cases, comparisons of the observed polarization directions with models of fracture orientation based on the fault movement indicate that the dominant horizontal polarization is near-orthogonal to the orientation of the expected predominant cracking direction. The results help to develop improved connections between fault mechanics and near-fault ground motion.

Pischiutta, M.; Salvini, F.; Fletcher, J.; Rovelli, A.; Ben-Zion, Y.

2012-03-01

336

Detection of gravity-induced polarity of cytoplasmic streaming in Chara  

Microsoft Academic Search

Summary Gravity induces a polarity of cytoplasmic streaming in vertically-oriented internodal cells of characean algae. The motive force that powers cytoplasmic streaming is generated at the ectoplasmic\\/endoplasmic interface. The velocity of streaming, which is about 100 µm\\/s at this interface, decreases with distance from the interface on either side of the cell to 0 µm\\/s near the middle. Therefore, when

M. P. Staves; R. Wayne; A. C. Leopold

1995-01-01

337

Spread of HTLV-I Between Lymphocytes by Virus-Induced Polarization of the Cytoskeleton  

Microsoft Academic Search

Cell contact is required for efficient transmission of human T cell leukemia virus- type 1 (HTLV-I) between cells and between individuals, because naturally infected lymphocytes produce virtually no cell-free infectious HTLV-I particles. However, the mechanism of cell-to-cell spread of HTLV-I is not understood. We show here that cell contact rapidly induces polarization of the cytoskeleton of the infected cell to

Tadahiko Igakura; Jane C. Stinchcombe; Peter K. C. Goon; Graham P. Taylor; Jonathan N. Weber; Gillian M. Griffiths; Yuetsu Tanaka; Mitsuhiro Osame; Charles R. M. Bangham

2003-01-01

338

A model-oriented approach to measure rain-induced cross-polarization  

Microsoft Academic Search

In this paper a new model oriented approach to measuring rain-induced cross-polarization is outlined: it aims at characterising\\u000a the physical properties of the depolarising medium rather than at directly measuring the channel depolarization, which is\\u000a the variable of direct interest for system design. This approach, which allows subsequent determination of depolarization\\u000a has the advantages of allowing a better understanding of

Carlo Capsoni; Aldo Paraboni; Francesco Fedi; Dario Maggiori

1981-01-01

339

Three-Dimensional Resistivity and Induced-Polarization Modeling Using Buried Electrodes  

Microsoft Academic Search

The three-dimensional induced-polarization and resistivity-modeling problem for buried source and receiver electrodes is solved by using a modified form of Barnett's surface-integral technique originally developed for surface-electrode configurations. Six different buried electrode configurations are considered in this study: three types of hole-to-hole configurations, hole-to-surface and surface-to-hole configurations, and the single hole (bipole-bipole) configuration. Results show there is no ''best'' method

Jeffrey J. Daniels

1977-01-01

340

MAUVE/SWIPE: an imaging instrument concept with multi-angular, -spectral, and -polarized capability for remote sensing of aerosols, ocean color, clouds, and vegetation from space  

NASA Astrophysics Data System (ADS)

The Monitoring Aerosols in the Ultraviolet Experiment (MAUVE) and the Short-Wave Infrared Polarimeter Experiment (SWIPE) instruments have been designed to collect, from a typical sun-synchronous polar orbit at 800 km altitude, global observations of the spectral, polarized, and directional radiance reflected by the earth-atmosphere system for a wide range of applications. Based on the heritage of the POLDER radiometer, the MAUVE/SWIPE instrument concept combines the merits of TOMS for observing in the ultra-violet, MISR for wide field-of-view range, MODIS, for multi-spectral aspects in the visible and near infrared, and the POLDER instrument for polarization. The instruments are camera systems with 2-dimensional detector arrays, allowing a 120-degree field-of-view with adequate ground resolution (i.e., 0.4 or 0.8 km at nadir) from satellite altitude. Multi-angle viewing is achieved by the along-track migration at spacecraft velocity of the 2-dimensional field-of-view. Between the cameras' optical assembly and detector array are two filter wheels, one carrying spectral filters, the other polarizing filters, allowing measurements of the first three Stokes parameters, I. Q, and V, of the incident radiation in 16 spectral bands optimally placed in the interval 350-2200 nm. The spectral range is 350-1050 nm for the MAUVE instrument and 1050-2200 nm for the SWIPE instrument. The radiometric requirements are defined to fully exploit the multi-angular, multi-spectral, and multi-polarized capability of the instruments. These include a wide dynamic range, a signal-to-noise ratio above 500 in all channels at maximum radiance level, i.e., when viewing a surface target of albedo equal to 1, and a noise-equivalent-differential reflectance better than 0.0005 at low signal level for a sun at zenith. To achieve daily global coverage, a pair of MAUVE and SWIPE instruments would be carried by each of two mini-satellites placed on interlaced orbits. The equator crossing time of the two satellites would be adjusted to allow simultaneous observations of the overlapping zone viewed from the two parallel orbits of the twin satellites. Using twin satellites instead of a single satellite would allow measurements in a more complete range of scattering angles. A MAUVE/SWIPE satellite mission would improve significantly the accuracy of ocean color observations from space, and will extend the retrieval of ocean optical properties to the ultra-violet, where they become very sensitive to detritus material and dissolved organic matter. It would also provide a complete description of the scattering and absorption properties of aerosol particles, as well as their size distribution and vertical distribution. Over land, the retrieved bidirectional reflectance function would allow a better classification of terrestrial vegetation and discrimination of surface types. The twin satellite concept, by providing stereoscopic capability, would offer the possibility to analyze the three-dimensional structure and radiative properties of cloud fields.

Frouin, Robert; Deschamps, Pierre-Yves; Rothschild, Richard; Stephan, Edward; Leblanc, Philippe; Duttweiler, Fred; Ghaemi, Tony; Riedi, Jérôme

2006-12-01

341

Polar surface effects on the thermal conductivity of ZnO nanowires: a shell-like surface reconstruction-induced  

E-print Network

Polar surface effects on the thermal conductivity of ZnO nanowires: a shell-like surface reconstruction-induced preserving mechanism Jin-Wu Jiang,*ab Harold S. Park*c and Timon Rabczuk*bd We perform molecular dynamics (MD) simulations to investigate the effect of polar surfaces on the thermal transport

Lin, Xi

342

An Open Source, Massively Parallel Code for Non-LTE Synthesis and Inversion of Spectral Lines and Zeeman-induced Stokes Profiles  

E-print Network

With the advent of a new generation of solar telescopes and instrumentation, the interpretation of chromospheric observations (in particular, spectro-polarimetry) requires new, suitable diagnostic tools. This paper describes a new code, NICOLE, that has been designed for Stokes non-LTE radiative transfer, both for synthesis and inversion of spectral lines and Zeeman-induced polarization profiles, spanning a wide range of atmospheric heights, from the photosphere to the chromosphere. The code fosters a number of unique features and capabilities and has been built from scratch with a powerful parallelization scheme that makes it suitable for application on massive datasets using large supercomputers. The source code is being publicly released, with the idea of facilitating future branching by other groups to augment its capabilities.

Socas-Navarro, H; Ramos, A Asensio; Bueno, J Trujillo; Cobo, B Ruiz

2014-01-01

343

Unexpected temporal evolution of atomic spectral lines of aluminum in a laser induced breakdown spectroscopy experiment  

NASA Astrophysics Data System (ADS)

The temporal evolution of the laser induced breakdown (LIBS) signal of a pure aluminum sample was studied under nitrogen and air atmospheres. In addition to the usual decrease of signal due to plasma cooling, unexpected temporal evolutions were observed for a spectral lines of aluminum, which revealed the existence of collisional energy transfer effects. Furthermore, molecular bands of AlN and AlO were observed in the LIBS spectra, indicating recombination of aluminum with the ambient gas. Within the experimental conditions reported in this study, both collisional energy transfer and recombination processes occurred around 1.5 ?s after the laser shot. This highlights the possible influence of collisional and chemical effects inside the plasma that can play a role on LIBS signals.

Saad, Rawad; L'Hermite, Daniel; Bousquet, Bruno

2014-11-01

344

Measurement of the induced ?0(1116) polarization in K+ electroproduction at CLAS  

NASA Astrophysics Data System (ADS)

We are using the p(e, e' K+p)?- reaction to perform a measurement of the induced polarization of the electroproduced L(1116) using its p?- parity-violating weak decay. This study uses the CEBAF Large Acceptance Spectrometer (CLAS) to detect the scattered electron, the kaon, and the decay proton over the kinematics 0.8 <= Q2 <= 3.5 GeV2, 1.6 <= W <= 3.0 GeV, and the full kaon CM angle range. In this experiment a 5.5 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The goal is to map out the kinematic dependencies for this polarization observable to provide new constraints for models of the electromagnetic production of K-hyperon final states. Along with previously published photo- and electroproduction cross sections and polarization observables from CLAS, SAPHIR, LEPS, and GRAAL, these data are needed in a coupled-channel analysis to identify previously unobserved s-channel resonances. Preliminary polarization results will be presented.

Gabrielyan, M.; Raue, B.; Carman, D. S.; Park, K.; CLAS Collaboration

2012-04-01

345

Measurement of the induced polarization of ?(1116) in kaon electroproduction with CLAS  

NASA Astrophysics Data System (ADS)

The CLAS Collaboration is using the p(e, e? K+ p)pi- reaction to perform a measurement of the induced polarization of the electroproduced ?(1116). The parity-violating weak decay of the ? into ppi- (64%) allows extraction of the recoil polarization of the ?. The present study uses the CEBAF Large Acceptance Spectrometer (CLAS) to detect the scattered electron, the kaon, and the decay proton. CLAS allows for a large kinematic acceptance in Q2 (0.8 ? Q2 ? 3.5 GeV2 ), W (1.6 ? W ? 3.0 GeV), as well as the kaon scattering angle. In this experiment a 5.499 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The goal is to map out the kinematic dependencies for this polarization observable to provide new constraints for theoretical models of the electromagnetic production of kaon-hyperon final states. Along with previously published photo- and electroproduction cross sections and polarization observables from CLAS, SAPHIR, and GRAAL, these data are needed in a coupled-channel analysis to identify previously unobserved s-channel resonances.

Gabrielyan, Marianna Y.

346

Induced polarized state in intentionally grown oxygen deficient KTaO{sub 3} thin films  

SciTech Connect

Deliberately oxygen deficient potassium tantalate thin films were grown by RF magnetron sputtering on Si/SiO{sub 2}/Ti/Pt substrates. Once they were structurally characterized, the effect of oxygen vacancies on their electric properties was addressed by measuring leakage currents, dielectric constant, electric polarization, and thermally stimulated depolarization currents. By using K{sub 2}O rich KTaO{sub 3} targets and specific deposition conditions, KTaO{sub 3-{delta}} oxygen deficient thin films with a K/Ta = 1 ratio were obtained. Room temperature X-ray diffraction patterns show that KTaO{sub 3-{delta}} thin films are under a compressive strain of 2.3% relative to KTaO{sub 3} crystals. Leakage current results reveal the presence of a conductive mechanism, following the Poole-Frenkel formalism. Furthermore, dielectric, polarization, and depolarization current measurements yield the existence of a polarized state below T{sub pol} {approx} 367 Degree-Sign C. A Cole-Cole dipolar relaxation was also ascertained apparently due to oxygen vacancies induced dipoles. After thermal annealing the films in an oxygen atmosphere at a temperature above T{sub pol}, the aforementioned polarized state is suppressed, associated with a drastic oxygen vacancies reduction emerging from annealing process.

Mota, D. A.; Romaguera-Barcelay, Y.; Tkach, A.; Agostinho Moreira, J.; Almeida, A. [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Science of University of Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Perez de la Cruz, J. [INESC TEC, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Vilarinho, P. M. [Department of Ceramics and Glass Engineering, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Tavares, P. B. [Centro de Quimica, Universidade de Tras-os-Montes e Alto Douro, Apartado 1013, 5001-801 Vila Real (Portugal)

2013-07-21

347

Fully spin-polarized transport induced by B doping in graphene nanoribbons  

NASA Astrophysics Data System (ADS)

B-doping induced spin polarization in zigzag-edged graphene nanoribbons is studied by density functional calculations by two kinds of doping: (1) doping only one B atom in the central scattering region; (2) periodically doping in the whole system. It is found that even a single B dopant may cause large spin polarization in the current, which can be understood by the breaking of spin-degeneracy due to the impurity atoms and the Fermi level shift resulting from the hole-donating of the B atoms. More interestingly, 100% spin polarized current under finite bias is obtained through periodical doping although the transmission function around the Fermi level is not 100% spin polarized. This can be interpreted by a rigid shift model of the special band structures of the left and right leads in this case. It demonstrates that only transmission function at equilibrium conditions is not sufficient in the study of electron transport, but current should be considered in certain situations.

Ding, Hong; Zheng, X. H.

2014-05-01

348

Induced polarized state in intentionally grown oxygen deficient KTaO3 thin films  

NASA Astrophysics Data System (ADS)

Deliberately oxygen deficient potassium tantalate thin films were grown by RF magnetron sputtering on Si/SiO2/Ti/Pt substrates. Once they were structurally characterized, the effect of oxygen vacancies on their electric properties was addressed by measuring leakage currents, dielectric constant, electric polarization, and thermally stimulated depolarization currents. By using K2O rich KTaO3 targets and specific deposition conditions, KTaO3-? oxygen deficient thin films with a K/Ta = 1 ratio were obtained. Room temperature X-ray diffraction patterns show that KTaO3-? thin films are under a compressive strain of 2.3% relative to KTaO3 crystals. Leakage current results reveal the presence of a conductive mechanism, following the Poole-Frenkel formalism. Furthermore, dielectric, polarization, and depolarization current measurements yield the existence of a polarized state below Tpol ˜ 367 °C. A Cole-Cole dipolar relaxation was also ascertained apparently due to oxygen vacancies induced dipoles. After thermal annealing the films in an oxygen atmosphere at a temperature above Tpol, the aforementioned polarized state is suppressed, associated with a drastic oxygen vacancies reduction emerging from annealing process.

Mota, D. A.; Romaguera-Barcelay, Y.; Tkach, A.; Pérez de la Cruz, J.; Vilarinho, P. M.; Tavares, P. B.; Agostinho Moreira, J.; Almeida, A.

2013-07-01

349

Measurement of the induced Lambda^0(1116) polarization in K^+ electroproduction at CLAS  

SciTech Connect

We are using the p(e,e'K{sup +}p){pi}{sup -} reaction to perform a measurement of the induced polarization of the electroproduced L(1116) using its p{pi}{sup -} parity-violating weak decay. This study uses the CEBAF Large Acceptance Spectrometer (CLAS) to detect the scattered electron, the kaon, and the decay proton over the kinematics 0.8 {le} Q{sup 2} {le} 3.5 GeV{sup 2}, 1.6 {le} W {le} 3.0 GeV, and the full kaon CM angle range. In this experiment a 5.5 GeV electron beam was incident upon an unpolarized liquid-hydrogen target. The goal is to map out the kinematic dependencies for this polarization observable to provide new constraints for models of the electromagnetic production of K-hyperon final states. Along with previously published photo- and electroproduction cross sections and polarization observables from CLAS, SAPHIR, LEPS, and GRAAL, these data are needed in a coupled-channel analysis to identify previously unobserved s-channel resonances. Preliminary polarization results will be presented.

M. Gabrielyan, B. Raue, D. S. Carman, K. Park

2012-04-01

350

Detection of global tropospheric clouds and polar stratospheric clouds over Antarctica using thermal infrared spectral data observed by TANSO-FTS/GOSAT  

NASA Astrophysics Data System (ADS)

Global tropospheric cloud distribution was derived from thermal infrared band data observed by Thermal And Near infrared Sensor for carbon Observation - Fourier Transform Spectrometer (TANSO-FTS) onboard Greenhouse gases Observation SATellite (GOSAT). It is expected that this band has ability to detect optically thin clouds compared with Cloud and Aerosol Imager (CAI) which is the other sensor on GOSAT. In addition, polar stratospheric clouds (PSCs) which can be harder to detect than the tropospheric clouds because of high reflectivity or low temperature of the surface and their low optical thickness were also detected. We have modified CO2 slicing method which was developed as one of the cirrus cloud detection techniques using thermal infrared band data to detect thin clouds more stably. The pseudo spectral channels were defined as sets of several actual spectral channels between 700cm-1 and 750cm-1 which have weighting function peak height in a same height range for each 0.5km. These pseudo channels were optimized with simulation studies using a multi-scattering radiative transfer code, Polarized radiance System for Transfer of Atmospheric Radiation (Pstar) 3 for several temperature profile patterns prepared based on latitudes and temperature at 500hPa. GOSAT data was analyzed with the combination of these pseudo channels determined for each of observation points from these simulations and the results were compared with the observational results from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) / Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The comparisons about global cloud are based on the coincident observations in 2010. Monthly occurrences of Antarctic PSCs were compared for each grid area from June to September in 2010. As a result, the correlation coefficients in each month are 0.76, 0.71, 0.75, and 0.61 relatively. Though that is low value in September, it can be explained by decrease of occurrences.

Someya, Yu; Imasu, Ryoichi; Ota, Yoshifumi; Saitoh, Naoko

2014-05-01

351

Reduction of polarization-induced performance degradation in WDM PON utilizing MQW-SLD-based broadband source.  

PubMed

We report on the reduction of polarization-induced performance degradation in WDM PON utilizing MQW-SLD-based ASE source for injection locking to FPLD. The results show that, to suppress the polarization-induced Q penalty sufficiently less than 0.5 dB, the MQW-SLD output should be depolarized within the locking range of the wavelength-locked FPLD. PMID:19550697

Park, Paul K J; Jun, S B; Kim, Hoon; Jung, D K; Lee, W R; Chung, Y C

2007-10-17

352

Heat-induced changes to lipid molecular structure in Vimy flaxseed: Spectral intensity and molecular clustering  

NASA Astrophysics Data System (ADS)

Autoclaving was used to manipulate nutrient utilization and availability. The objectives of this study were to characterize any changes of the functional groups mainly associated with lipid structure in flaxseed ( Linum usitatissimum, cv. Vimy), that occurred on a molecular level during the treatment process using infrared Fourier transform molecular spectroscopy. The parameters included lipid CH 3 asymmetric (ca. 2959 cm -1), CH 2 asymmetric (ca. 2928 cm -1), CH 3 symmetric (ca. 2871 cm -1) and CH 2 symmetric (ca. 2954 cm -1) functional groups, lipid carbonyl C dbnd O ester group (ca. 1745 cm -1), lipid unsaturation group (CH attached to C dbnd C) (ca. 3010 cm -1) as well as their ratios. Hierarchical cluster analysis (CLA) and principal components analysis (PCA) were conducted to identify molecular spectral differences. Flaxseed samples were kept raw for the control or autoclaved in batches at 120 °C for 20, 40 or 60 min for treatments 1, 2 and 3, respectively. Molecular spectral analysis of lipid functional group ratios showed a significant decrease ( P < 0.05) in the CH 2 asymmetric to CH 3 asymmetric stretching band peak intensity ratios for the flaxseed. There were linear and quadratic effects ( P < 0.05) of the treatment time from 0, 20, 40 and 60 min on the ratios of the CH 2 asymmetric to CH 3 asymmetric stretching vibration intensity. Autoclaving had no significant effect ( P > 0.05) on lipid carbonyl C dbnd O ester group and lipid unsaturation group (CH attached to C dbnd C) (with average spectral peak area intensities of 138.3 and 68.8 IR intensity units, respectively). Multivariate molecular spectral analyses, CLA and PCA, were unable to make distinctions between the different treatment original spectra at the CH 3 and CH 2 asymmetric and symmetric region (ca. 2988-2790 cm -1). The results indicated that autoclaving had an impact to the mid-infrared molecular spectrum of flaxseed to identify heat-induced changes in lipid conformation. A future study is needed to quantify the relationship between lipid molecular structure changes and functionality/availability.

Yu, Peiqiang; Damiran, Daalkhaijav

2011-06-01

353

Vector magnetometry based on electromagnetically induced transparency in linearly polarized light  

SciTech Connect

We develop a generalized principle of electromagnetically induced transparency (EIT) vector magnetometry based on high-contrast EIT resonances and the symmetry of atom-light interaction in the linearly polarized bichromatic fields. Operation of such vector magnetometer on the D{sub 1} line of {sup 87}Rb has been demonstrated. The proposed compass-magnetometer has an increased immunity to shifts produced by quadratic Zeeman and ac-Stark effects, as well as by atom-buffer gas and atom-atom collisions. In our proof-of-principle experiment the detected angular sensitivity to magnetic field orientation is 10{sup -3} deg/Hz{sup 1/2}, which is limited by laser intensity fluctuations, light polarization quality, and magnitude of the magnetic field.

Yudin, V. I. [Institute of Laser Physics, Siberian Branch of RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Novosibirsk State Technical University, Novosibirsk 630092 (Russian Federation); Taichenachev, A. V. [Institute of Laser Physics, Siberian Branch of RAS, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Dudin, Y. O. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430 (United States); Velichansky, V. L. [Moscow State Engineering and Physics Institute, Moscow 115409 (Russian Federation); Lebedev Physical Institute, RAS, Moscow 117924 (Russian Federation); Zibrov, A. S. [Physics Department, Harvard University, Cambridge, Massachusetts 02138 (United States); Zibrov, S. A. [Lebedev Physical Institute, RAS, Moscow 117924 (Russian Federation)

2010-09-15

354

ANALYSIS OF SEEING-INDUCED POLARIZATION CROSS-TALK AND MODULATION SCHEME PERFORMANCE  

SciTech Connect

We analyze the generation of polarization cross-talk in Stokes polarimeters by atmospheric seeing, and its effects on the noise statistics of spectropolarimetric measurements for both single-beam and dual-beam instruments. We investigate the time evolution of seeing-induced correlations between different states of one modulation cycle and compare the response to these correlations of two popular polarization modulation schemes in a dual-beam system. Extension of the formalism to encompass an arbitrary number of modulation cycles enables us to compare our results with earlier work. Even though we discuss examples pertinent to solar physics, the general treatment of the subject and its fundamental results might be useful to a wider community.

Casini, R.; De Wijn, A. G.; Judge, P. G. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States)

2012-09-20

355

Algorithm to Retrieve Aerosol Optical Properties From High-Spectral-Resolution Lidar and Polarization Mie-Scattering Lidar Measurements  

Microsoft Academic Search

We developed an algorithm to estimate the vertical profiles of extinction coefficients at 532 nm for three aerosol types that are water-soluble, soot, and dust particles, using the extinction and backscattering coefficients at 532 nm for total aerosols derived from high-spectral-resolution lidar (HSRL) measurements and the receiving signal at 1064 nm and total depolarization ratio at 532 nm measured with

Tomoaki Nishizawa; Nobuo Sugimoto; Ichiro Matsui; Atsushi Shimizu; Boyan Tatarov; Hajime Okamoto

2008-01-01

356

Mycobacterium tuberculosislpdC, Rv0462, induces dendritic cell maturation and Th1 polarization  

SciTech Connect

Highlights: {yields} Treatment with Rv0462 induces the expression of surface molecules and the production of cytokines in DCs. {yields} Rv0462 induces the activation of MAPKs. {yields} Rv0462-treated DCs enhances the proliferation of CD4{sup +} T cells. -- Abstract: Mycobacterium tuberculosis, the etiological factor of pulmonary tuberculosis, causes significant morbidity and mortality worldwide. Activation of host immune responses for containment of mycobacterial infections involves participation of innate immune cells, such as dendritic cells (DCs). In this study, we demonstrated that the gene encoding lipoamide dehydrogenase C (lpdC) from M. tuberculosis, Rv0462, induce maturation and activation of DCs involved in the MAPKs signaling pathway. Moreover, Rv0462-treated DCs activated naive T cells, polarized CD4{sup +} and CD8{sup +} T cells to secrete IFN-{gamma} in syngeneic mixed lymphocyte reactions, which would be expected to contribute to Th1 polarization of the immune response. Our results suggest that Rv0462 can contribute to the innate and adaptive immune responses during tuberculosis infection, and thus modulate the clinical course of tuberculosis.

Heo, Deok Rim [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of)] [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Shin, Sung Jae; Kim, Woo Sik [Department of Microbiology, College of Medicine, Chungnam National University, Munwha-Dong, Jung-Ku, Daejeon 301-747 (Korea, Republic of)] [Department of Microbiology, College of Medicine, Chungnam National University, Munwha-Dong, Jung-Ku, Daejeon 301-747 (Korea, Republic of); Noh, Kyung Tae; Park, Jin Wook; Son, Kwang Hee [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of)] [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Park, Won Sun [Department of Physiology, Kangwon National University, School of Medicine, Chuncheon 200-701 (Korea, Republic of)] [Department of Physiology, Kangwon National University, School of Medicine, Chuncheon 200-701 (Korea, Republic of); Lee, Min-Goo [Department of Physiology, Korea University, College of Medicine, Anam-dong, Sungbuk-Gu, Seoul 136-705 (Korea, Republic of)] [Department of Physiology, Korea University, College of Medicine, Anam-dong, Sungbuk-Gu, Seoul 136-705 (Korea, Republic of); Kim, Daejin [Department of Anatomy, Chung-Ang University, College of Medicine, 221 Heuksuk-Dong, Dongjak-Ku, Seoul 156-756 (Korea, Republic of)] [Department of Anatomy, Chung-Ang University, College of Medicine, 221 Heuksuk-Dong, Dongjak-Ku, Seoul 156-756 (Korea, Republic of); Shin, Yong Kyoo [Department of Pharmacology, Chung-Ang University, College of Medicine, 221 Heuksuk-Dong, Dongjak-Ku, Seoul 156-756 (Korea, Republic of)] [Department of Pharmacology, Chung-Ang University, College of Medicine, 221 Heuksuk-Dong, Dongjak-Ku, Seoul 156-756 (Korea, Republic of); Jung, In Duk, E-mail: jungid@pusan.ac.kr [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Research Institute of Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Park, Yeong-Min, E-mail: immunpym@pusan.ac.kr [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of) [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Research Institute of Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of)

2011-08-05

357

Electrotonic measurements by electric field-induced polarization in neurons: theory and experimental estimation.  

PubMed Central

We present a theory for estimation of the dendritic electrotonic length constant and the membrane time constant from the transmembrane potential (TMP) induced by an applied electric field. The theory is adapted to morphologically defined neurons with homogeneous passive electric properties. Frequency characteristics and transients at the onset and offset of the DC field are considered. Two relations are useful for estimating the electrotonic parameters: 1) steady-state polarization versus the dendritic electrotonic length constant; 2) membrane time constant versus length constant. These relations are monotonic and may provide a unique estimate of the electrotonic parameters for 3D-reconstructed neurons. Equivalent tip-to-tip electrotonic length of the dendritic tree was estimated by measuring the equalization time of the field-induced TMP. For 11 turtle spinal motoneurons, the electrotonic length from tip to tip of the dendrites was in the range of 1-2.5 lambda, whereas classical estimation using injection of current pulses gave an average dendrite length of 0.9-1.1 lambda. For seven ventral horn interneurons, the estimates were 0.7-2.6 lambda and 0.6-0.9 lambda, respectively. The measurements of the field-induced polarization promise to be a useful addition to the conventional methods using microelectrode stimulation. PMID:9414215

Svirskis, G; Baginskas, A; Hounsgaard, J; Gutman, A

1997-01-01

358

Vacuum polarization induced by a cosmic string in anti-de Sitter spacetime  

E-print Network

In this paper we investigate the vacuum expectation values (VEVs) of the field squared and the energy-momentum tensor associated with a massive scalar quantum field induced by a generalized cosmic string in D-dimensional anti-de Sitter (AdS) spacetime. In order to develop this analysis we evaluate the corresponding Wightman function. As we shall observe, this function is expressed as the sum of two terms: the first one corresponds to the Wightman function in pure AdS bulk and the second one is induced by the presence of the string. The second contribution is finite at coincidence limit and is used to provide closed expressions for the parts in the VEVs of the field squared and the energy-momentum tensor induced by the presence of the string. Because the analysis of vacuum polarizations effects in pure AdS spacetime have been developed in the literature, here we are mainly interested in the investigation of string-induced effects. We show that the curvature of the background spacetime has an essential influence on the VEVs at distances larger than the curvature radius. In particular, at large distances the decay of the string-induced VEVs is power-law for both massless and massive fields. The string-induced parts vanish on the AdS boundary and they dominate the pure AdS part for points near the AdS horizon.

E. R. Bezerra de Mello; A. A. Saharian

2011-10-10

359

Self-screening of the quantum confined Stark effect by the polarization induced bulk charges in the quantum barriers  

NASA Astrophysics Data System (ADS)

InGaN/GaN light-emitting diodes (LEDs) grown along the polar orientations significantly suffer from the quantum confined Stark effect (QCSE) caused by the strong polarization induced electric field in the quantum wells, which is a fundamental problem intrinsic to the III-nitrides. Here, we show that the QCSE is self-screened by the polarization induced bulk charges enabled by designing quantum barriers. The InN composition of the InGaN quantum barrier graded along the growth orientation opportunely generates the polarization induced bulk charges in the quantum barrier, which well compensate the polarization induced interface charges, thus avoiding the electric field in the quantum wells. Consequently, the optical output power and the external quantum efficiency are substantially improved for the LEDs. The ability to self-screen the QCSE using polarization induced bulk charges opens up new possibilities for device engineering of III-nitrides not only in LEDs but also in other optoelectronic devices.

Zhang, Zi-Hui; Liu, Wei; Ju, Zhengang; Tiam Tan, Swee; Ji, Yun; Kyaw, Zabu; Zhang, Xueliang; Wang, Liancheng; Wei Sun, Xiao; Volkan Demir, Hilmi

2014-06-01

360

Cytochalasin-Induced Actin Disruption of Polarized Enterocytes Can Augment Internalization of Bacteria  

PubMed Central

Cytochalasin-induced actin disruption has often been associated with decreased bacterial internalization by cultured epithelial cells, although polarized enterocytes have not been systematically studied. In assays using confluent polarized HT-29 enterocytes, cytochalasin D appeared to increase internalization of wild-type Salmonella typhimurium, Proteus mirabilis, and Escherichia coli. HeLa and HEp-2 epithelial cells, as well as HT-29 and Caco-2 enterocytes, were used to clarify this unexpected observation. Resulting data showed that cytochalasin D was associated with increased internalization of S. typhimurium and P. mirabilis by both HT-29 and Caco-2 enterocytes and with increased internalization of E. coli by HT-29 enterocytes; with either HeLa or HEp-2 cells, cytochalasin was associated with no change or a decrease in internalization of these same bacterial strains. Cytochalasin caused decreased internalization of Listeria monocytogenes by HT-29, Caco-2, HeLa, and HEp-2 cells, indicating that cytochalasin did not consistently augment bacterial internalization by polarized enterocytes. Fluorescein-labeled phalloidin confirmed marked disruption of filamentous actin in cytochalasin-treated HT-29, Caco-2, HeLa, and HEp-2 cells. Cytochalasin had no noticeable effect on epithelial viability but caused distorted apical microvilli, cell rounding, and separation of adjacent enterocytes in confluent cultures (with a corresponding decrease in transepithelial electrical resistance). Scanning electron microscopy showed that cytochalasin-induced enhanced bacterial internalization was associated with preferential bacterial adherence on the exposed enterocyte lateral surface. Colchicine, used to disrupt microtubules, had no noticeable effect on bacterial internalization by HT-29 or Caco-2 enterocytes. These data indicated that for HT-29 and Caco-2 enterocytes, cytochalasin-induced disruption of filamentous actin might augment internalization of some bacterial species by a mechanism that appeared to involve exposure of the enterocyte lateral surface. PMID:9596696

Wells, Carol L.; van de Westerlo, Elisabeth M. A.; Jechorek, Robert P.; Haines, Holly M.; Erlandsen, Stanley L.

1998-01-01

361

Modeling the impact of spectral sensor configurations on the FLD retrieval accuracy of sun-induced chlorophyll fluorescence  

Microsoft Academic Search

Chlorophyll fluorescence is related to photosynthesis and can serve as a remote sensing proxy for estimating photosynthetic energy conversion and carbon uptake. Recent advances in sensor technology allow remote measurements of the sun-induced chlorophyll fluorescence signal (Fs) at leaf and canopy scale. The commonly used Fraunhofer Line Depth (FLD) principle exploits spectrally narrow atmospheric oxygen absorption bands and relates Fs

Alexander Damm; André Erler; Walter Hillen; Michele Meroni; Michael E. Schaepman; Wout Verhoef; Uwe Rascher

2011-01-01

362

Analysis and measurement of root-mean-squared bandwidth of cross-phase-modulation-induced spectral broadening  

Microsoft Academic Search

The root-mean-squared bandwidth of spectral broadening induced by cross-phase modulation is derived analytically for a two-channel system consisting of a pump and probe channel. The pump channel is randomly modulated by binary data and the probe channel is a weak continuous-wave channel. The analytical expression is verified by experiments

Keang-Po Ho; Eddie Ting-Pong Kong; Lai Yin Chan; Lian-Kuan Chen; Frank Tong

1999-01-01

363

Degeneracy doubling and sublattice polarization in strain-induced pseudo-Landau levels  

NASA Astrophysics Data System (ADS)

The degeneracy and spatial support of pseudo-Landau levels (pLLs) in strained honeycomb lattices systematically depends on the geometry; for instance, in hexagonal and rectangular flakes the zeroth pLL displays a twofold increased degeneracy, while the characteristic sublattice polarization of the zeroth pLL is only fully realized in a zigzag-terminated triangle. These features are dictated by algebraic constraints in the atomistic theory and signify a departure from the standard picture in which all qualitative differences between pLLs and Landau levels induced by a magnetic field trace back to the valley antisymmetry of the pseudomagnetic field.

Poli, Charles; Arkinstall, Jake; Schomerus, Henning

2014-10-01

364

Altered Landscapes and Groundwater Sustainability — Exploring Impacts with Induced Polarization, DC Resistivity, and Thermal Tracing  

NASA Astrophysics Data System (ADS)

Anthropogenically impacted landscapes constitute rising proportions of the Earth’s surface that are characterized by generally elevated nutrient and sediment loadings concurrent with increased consumptive water withdrawals. In recent years a growing number of hydraulically engineered riparian habitat restoration projects have attempted to ameliorate negative impacts of land use on groundwater-surface water systems resulting, e.g., from agricultural practices and urban development. Often the nature of groundwater-surface water interactions in pre- and minimally altered systems is poorly known, making it difficult to assess the impacts of land use and restoration projects on groundwater sustainability. Traditional assessments of surface water parameters (flow, temperature, dissolved oxygen, biotic composition, etc.) can be complemented by hydraulic and thermal measurements to better understand the important role played by groundwater-surface water interactions. Hydraulic and thermal measurements are usually limited to point samples, however, making non-invasive and spatially extensive geophysical characterizations an attractive additional tool. Groundwater-surface water interactions along the Smith River, a tributary to the Missouri River in Montana, and Fish Creek and Flat Creek, tributaries to the Snake River in Wyoming, are being examined using a combination of hydraulic measurements, thermal tracing, and electrical-property imaging. Ninety-two direct-current (DC) resistivity and induced polarization cross sections were obtained at stream transects covering a wide variety of hydrogeologic settings ranging from shallow bedrock to thick alluvial sequences, nature of groundwater-surface water interactions (always gaining, always losing, or seasonally varying) and anthropogenic impacts (minimal low-intensity agriculture to major landscape engineering, including channel reconstruction). DC resistivity and induced polarization delineated mutually distinct features related to hydraulic architecture. For example, induced polarization imaging resolved channel-edge muck deposits that are presumed to be sites of low hydraulic conductivity, chemical reduction, and metal accumulation. DC resistivity delineated bedrock-alluvium contacts and showed potential for tracking changes in salinization. While electrical properties cannot substitute for hydraulic and thermal data, the addition of relatively rapidly acquired, spatially extensive resistivity and induced polarization imaging offers synergistic opportunities for interpretive hydrologic investigations.

Eddy-Miller, C.; Caldwell, R.; Wheeler, J.; McCarthy, P.; Binley, A. M.; Constantz, J. E.; Stonestrom, D. A.

2009-12-01

365

Shear wave induced resonance elastography of spherical masses with polarized torsional waves  

NASA Astrophysics Data System (ADS)

Shear wave induced resonance (SWIR) is a technique for dynamic ultrasound elastography of confined mechanical inclusions. It was developed for breast tumor imaging and tissue characterization. This method relies on the polarization of torsional shear waves modeled with the Helmholtz equation in spherical coordinates. To validate modeling, an invitro set-up was used to measure and image the first three eigenfrequencies and eigenmodes of a soft sphere. A preliminary invivo SWIR measurement on a breast fibroadenoma is also reported. Results revealed the potential of SWIR elastography to detect and mechanically characterize breast lesions for early cancer detection.

Hadj Henni, Anis; Schmitt, Cédric; Trop, Isabelle; Cloutier, Guy

2012-03-01

366

Gravitational Wave Induced Rotation of the Plane of Polarization of Pulsar Signals  

E-print Network

We derive in this an expression for the rotation of plane of polarization, of an electromagnetic wave, induced by the field of a gravitational wave propagating along the same direction $\\approx \\f{G\\mu d^2\\Omega^4}{3\\o}$, $\\o$ and $\\Omega$ being their respective frequencies using the geometrical optics limit of the wave equation for fields. Estimating the effect for the case of pulses from binary pulsars, one finds it too small to be observable, there could be other sources like inspiralling binary or an asymmetric neutron star where the effect could be in the observable region.

A. R. Prasanna; S. Mohanty

2001-10-29

367

Degeneracy doubling and sublattice polarization in strain-induced pseudo-Landau levels  

E-print Network

The degeneracy and spatial support of pseudo-Landau levels (pLLs) in strained honeycomb lattices systematically depends on the geometry -- for instance, in hexagonal and rectangular flakes the 0th pLL displays a twofold increased degeneracy, while the characteristic sublattice polarization of the 0th pLL is only fully realized in a zigzag-terminated triangle. These features are dictated by algebraic constraints in the atomistic theory, and signify a departure from the standard picture in which all qualitative differences between pLLs and Landau levels induced by a magnetic field trace back to the valley-antisymmetry of the pseudomagnetic field.

Poli, Charles; Schomerus, Henning

2014-01-01

368

Interaction-induced coherence among polar bosons stored in triple-well potentials  

E-print Network

We study first-order spatial coherence for interacting polar bosons trapped in triple-well potentials. It is argued that besides the well-known coherence produced by couplings related to tunneling between the sites, there exists a nonlocal coherence predominantly determined by intersite interactions, which prevails between the outer sites of the triple well when their total filling is odd. We find that the nonlocal interaction-induced coherence originates from the superposition of degenerate many-body states in symmetric triple wells, and demonstrate its robustness against perturbations due to various tunneling mechanisms and thermal fluctuations.

Bo Xiong; Uwe R. Fischer

2012-12-12

369

Performance degradation induced by polarization-dependent loss in optical fiber transmission systems with and without polarization-mode dispersion  

Microsoft Academic Search

The performance degradation caused by polarization-dependent loss (PDL) in optical fiber transmission systems in both the absence and presence of polarization-mode dispersion (PMD) is studied. First a simple theory is given to show how PDL affects the system performance and then extensive simulation results are presented. We show that PDL causes a much larger fluctuation of optical-signal-to-orthogonal-noise ratio (OSNRort) than

Chongjin Xie; Linn F. Mollenauer

2003-01-01

370

Parahydrogen-induced polarization of carboxylic acids: a pilot study of valproic acid and related structures.  

PubMed

Parahydrogen-induced polarization (PHIP) is a promising new tool for medical applications of MR, including MRI. The PHIP technique can be used to transfer high non-Boltzmann polarization, derived from parahydrogen, to isotopes with a low natural abundance or low gyromagnetic ratio (e.g. (13)C), thus improving the signal-to-noise ratio by several orders of magnitude. A few molecules acting as metabolic sensors have already been hyperpolarized with PHIP, but the direct hyperpolarization of drugs used to treat neurological disorders has not been accomplished until now. Here, we report on the first successful hyperpolarization of valproate (valproic acid, VPA), an important and commonly used antiepileptic drug. Hyperpolarization was confirmed by detecting the corresponding signal patterns in the (1)H NMR spectrum. To identify the optimal experimental conditions for the conversion of an appropriate VPA precursor, structurally related molecules with different side chains were analyzed in different solvents using various catalytic systems. The presented results include hyperpolarized (13)C NMR spectra and proton images of related systems, confirming their applicability for MR studies. PHIP-based polarization enhancement may provide a new MR technique to monitor the spatial distribution of valproate in brain tissue and to analyze metabolic pathways after valproate administration. PMID:24812006

Lego, Denise; Plaumann, Markus; Trantzschel, Thomas; Bargon, Joachim; Scheich, Henning; Buntkowsky, Gerd; Gutmann, Torsten; Sauer, Grit; Bernarding, Johannes; Bommerich, Ute

2014-07-01

371

Assessment of system penalties induced by polarization mode dispersion in a 5 Gb\\/s optically amplified transoceanic link  

Microsoft Academic Search

The system penalties induced by polarization mode dispersion (PMD) in a 5 Gb\\/s optically amplified link are analyzed. A relation between differential group delays and system penalties is obtained from numerical simulations and used to derive analytic formulas for probability density functions of system penalties. Cumulated probabilities show that PMDs higher than 20 ps can induce significant fluctuations of the

F. Bruyere; O. Audouin

1994-01-01

372

THE JOURNAL OF CHEMICAL PHYSICS 135, 024201 (2011) Stark-induced adiabatic Raman passage for preparing polarized molecules  

E-print Network

THE JOURNAL OF CHEMICAL PHYSICS 135, 024201 (2011) Stark-induced adiabatic Raman passage for preparing polarized molecules Nandini Mukherjee and Richard N. Zarea) Department of Chemistry, Stanford online 8 July 2011) We propose a method based on Stark-induced adiabatic Raman passage (SARP

Zare, Richard N.

373

Radiation-induced attenuation in polarization maintaining fibers - Low dose rate response, stress, and materials effects  

NASA Astrophysics Data System (ADS)

The loss induced in polarization-maintaining (PM) fibers by a low dose rate of less than 0.01 Gy/h, where 1 Gy = 100 rads(Si) radiation exposure, has been found to vary from less than 0.4 to about 6 dB/km-10 Gy, depending on the wavelength of measurement and the fiber. Correlations have been established between low dose rate response and the 'permanent' induced loss determined by fitting the recovery of the induced loss following high dose rate exposure to nth-order kinetics. Using this technique, both 0.85- and 1.3-micron PM fibers have been found which show virtually no permanent incremental loss and would therefore appear to be resistant to low dose rate radiation environments. The asymmetric stress inherent in PM fibers has been shown to reduce the permanent induced loss, while the recovery of the radiation-induced attenuation was found to be enhanced in fibers with Ge-F-doped silica clads.

Friebele, E. Joseph; Gingerich, Michael E.; Brambani, Louise A.; Hickey, Steven J.; Onstott, James R.

1989-12-01

374

Self-induced polar order of active Brownian particles in a harmonic trap  

E-print Network

Hydrodynamically interacting active particles in an external harmonic potential form a self-assembled fluid pump at large enough P\\'eclet numbers. Here, we give a quantitative criterion for the formation of the pump and show that particle orientations align in the self-induced flow field in surprising analogy to ferromagnetic order where the active P\\'eclet number plays the role of inverse temperature. The particle orientations follow a Boltzmann distribution $\\Phi(\\mathbf{p}) \\sim \\exp(A p_z)$ where the ordering mean field $A$ scales with active P\\'eclet number and polar order parameter. The mean flow field in which the particles' swimming directions align corresponds to a regularized stokeslet with strength proportional to swimming speed. Analytic mean-field results are compared with results from Brownian dynamics simulations with hydrodynamic interactions included and are found to capture the self-induced alignment very well.

Marc Hennes; Katrin Wolff; Holger Stark

2014-02-06

375

Interleukin-11 induces Th2 polarization of human CD4(+) T cells.  

PubMed

Exploration of the immunomodulatory activities of the multifunctional cytokine interleukin-11 (IL-11) has prompted several therapeutic applications. The immunomodulatory effects of IL-11 on human antigen-presenting cells and on T cells were investigated. IL-11 inhibited IL-12 production by activated CD14(+) monocytes, but not by mature dendritic cells (DCs) stimulated via CD40 ligation. Moreover, IL-11 did not affect either DC maturation, as demonstrated by phenotypic analysis and evaluation of cytokine production, or DC generation from progenitor cells in the presence of specific growth factors. Molecular analysis demonstrated the expression of IL-11 receptor messenger RNA in highly purified CD14(+) monocytes, CD19(+) B cells, CD8(+), and CD4(+) T cells, and CD4(+)CD45RA(+) naive T lymphocytes. In keeping with this finding, IL-11 directly prevented Th1 polarization of highly purified CD4(+)CD45RA(+) naive T cells stimulated with anti-CD3/CD28 antibodies, as demonstrated by significant increases of IL-4 and IL-5, by significantly decreased interferon-gamma production and by flow cytometry intracellular staining of cytokines. Coincubation of naive T cells with DCs, the most potent stimulators of Th1 differentiation, did not revert IL-11-mediated Th2 polarization. Furthermore, parallel experiments demonstrated that the activity of IL-11 was comparable with that induced by IL-4, the most effective Th2-polarizing cytokine. Taken together, these findings show that IL-11 inhibits Th1 polarization by exerting a direct effect on human T lymphocytes and by reducing IL-12 production by macrophages. Conversely, IL-11 does not exert any activity on DCs. This suggests that IL-11 could have therapeutic potential for diseases where Th1 responses play a dominant pathogenic role. PMID:11313268

Curti, A; Ratta, M; Corinti, S; Girolomoni, G; Ricci, F; Tazzari, P; Siena, M; Grande, A; Fogli, M; Tura, S; Lemoli, R M

2001-05-01

376

Wnt signaling gradients establish planar cell polarity by inducing Vangl2 phosphorylation through Ror2  

PubMed Central

It is fundamentally important that signaling gradients provide positional information to govern morphogenesis of multicellular organisms. Morphogen gradients can generate different cell types in specific spatial order at distinct threshold concentrations. However, it is largely unknown whether and how signaling gradients also control cell polarities by acting as global cues. Here we show that Wnt signaling gradient provides directional information to a field of cells. Vangl2, a core component in planar cell polarity, forms Wnt-induced receptor complex with Ror2 to sense Wnt dosages. Wnts dose-dependently induce Vangl2 phosphorylation of Serine/Threonine residues and Vangl2 activities depend on its levels of phosphorylation. In the limb bud, Wnt5a signaling gradient controls limb elongation by establishing PCP in chondrocytes along the proximal-distal axis through regulating Vangl2 phosphorylation. Our studies have provided new insight to Robinow Syndrome, Brachydactyly Type B1 and spinal bifida which are caused by mutations in human ROR2, WNT5A or VANGL. PMID:21316585

Gao, Bo; Song, Hai; Bishop, Kevin; Elliot, Gene; Garrett, Lisa; English, Milton; Andre, Philipp; Robinson, James; Sood, Raman; Minami, Yasuhiro; Economides, Aris N.; Yang, Yingzi

2011-01-01

377

Polar lipids from the marine macroalga Palmaria palmata inhibit lipopolysaccharide-induced nitric oxide production in RAW264.7 macrophage cells.  

PubMed

The EtOAc soluble fraction of a MeOH/CHCl3 extract of Palmaria palmata showed strong nitric oxide (NO) inhibitory activity against lipopolysaccharide (LPS)-induced NO production in murine RAW264.7 cells. NO inhibition-guided isolation led to identification of three new polar lipids including a sulfoquinovosyl diacylglycerol (SQDG) (2S)-1-O-eicosapentaenoyl-2-O-myristoyl-3-O-(6-sulfo-?-D-quinovopyranosyl)-glycerol (1) and two phosphatidylglycerols, 1-O-eicosapentaenoyl-2-O-trans-3-hexadecenoyl-3-phospho-(1'-glycerol)-glycerol (3) and 1-O-eicosapentaenoyl-2-O-palmitoyl-3-phospho-(1'-glycerol)-glycerol (4) from the EtOAc fraction. Seven known lipids were also isolated including a SQDG (2), a phospholipid (5) and five galactolipids (6-10). Structures of the isolated lipids were elucidated by spectral analyses. The isolated SQDGs, phosphatidylglycerols and phospholipid possessed strong and dose-dependent NO inhibitory activity compared to N(G)-methyl-L-arginine acetate salt (L-NMMA), a well-known NO inhibitor used as a positive control. Further study suggested that these polar lipids suppressed NO production through down-regulation of inducible nitric oxide synthase (iNOS). PMID:24569177

Banskota, Arjun H; Stefanova, Roumiana; Sperker, Sandra; Lall, Santosh P; Craigie, James S; Hafting, Jeff T; Critchley, Alan T

2014-05-01

378

Thermal and kinematic corrections to the microwave background polarization induced by galaxy clusters along the line of sight  

E-print Network

We derive analytic expressions for the leading-order corrections to the polarization induced in the cosmic microwave background (CMB) due to scattering off hot electrons in galaxy clusters along the line of sight. For a thermal distribution of electrons with a kinetic temperature of 10 keV and a bulk peculiar velocity of 1000 km/s, the dominant corrections to the polarization induced by the primordial CMB quadrupole and the cluster peculiar velocity arise from electron thermal motion and are at the level of 10 per cent in each case, near the peak of the polarization signal. When more sensitive measurements become feasible, these effects will be significant for the determination of transverse peculiar velocities, and the value of the CMB quadrupole at the cluster redshift, via the cluster polarization route.

Anthony Challinor; Matthew Ford; Anthony Lasenby

1999-05-18

379

Magnetically induced electric polarization in an organometallic magnet V. S. Zapf,1 M. Kenzelmann,2 F. Wolff-Fabris,1,* F. Balakirev,1  

E-print Network

Magnetically induced electric polarization in an organometallic magnet V. S. Zapf,1 M. Kenzelmann,2 polarization in the presence of magnetic fields. Unlike many magnetically induced multiferroics, the mag- netic coupling is obtained in so-called magnetically induced multiferroics where ferroelectricity arises directly

McQuade, D. Tyler

380

Orthogonal polarization mode coupling for pure twisted polarization maintaining fiber Bragg gratings.  

PubMed

Spectral characteristics of orthogonal polarization mode coupling for pure twisted polarization maintaining fiber Bragg gratings (PM-FBG) are proposed and analyzed experimentally and theoretically. Different from the polarization mode coupling in PM-FBG due to side pressure, a resonant peak at the middle of two orthogonal polarization modes is found when the PM-FBG is twisted purely which is attributed to the cross coupling of polarization modes. Its intensity increases with the twisting rate. A new coupled mode equation is built to describe the pure twist polarization mode coupling, in which both the normal strain induced by strain-applied parts and the tangential strain induced by twisting are taken into consideration and expressed in a unified coordinate. The novel phenomenon and its explanation are believed to be helpful for PM-FBG applications in fiber sensor and laser technologies. PMID:23263124

Yang, Fei; Fang, Zujie; Pan, Zhengqing; Ye, Qing; Cai, Haiwen; Qu, Ronghui

2012-12-17

381

Mosaic analysis in the drosophila ovary reveals a common hedgehog-inducible precursor stage for stalk and polar cells.  

PubMed Central

The fates of two small subgroups of the ovarian follicle cells appear to be linked: mutations in Notch, Delta, fs(1)Yb, or hedgehog cause simultaneous defects in the specification of stalk cells and polar cells. Both of these subgroups are determined in the germarium, and both cease division early in oogenesis. To test the possibility that these subgroups are related by lineage, we generated dominantly marked mitotic clones in ovaries. Small, restricted clones in stalk cells and polar cells were found adjacent to each other at a frequency much too high to be explained by independent induction. We therefore propose a model in which stalk cells and polar cells are derived from a precursor population that is distinct from the precursors for other follicle cells. We support and extend this model by characterization of mutants that affect stalk and polar cell formation. We find that ectopic expression of Hedgehog can induce both polar and stalk cell fate, presumably by acting on the precursor stage. In contrast, we find that stall affects neither the induction of the precursors nor the decision between the stalk cell and polar cell fate but, rather, some later differentiation step of stalk cells. In addition, we show that ectopic polar and stalk cells disturb the anterior-posterior polarity of the underlying oocyte. PMID:9927465

Tworoger, M; Larkin, M K; Bryant, Z; Ruohola-Baker, H

1999-01-01

382

Diffraction-induced spectral anomalies for information encoding and information hiding - Possibilities and limitations  

NASA Astrophysics Data System (ADS)

It has been shown both theoretically and experimentally that drastic spectral changes take place around phase singularity and the shift in the spectral lines gives rise to the phenomenon called spectral switching. The shift of spectral lines towards the blue end or towards the red end of the spectrum might perhaps be used in free space communication applications. In more recent investigations, the possibility of information encoding with spectral anomalies have been discussed for two different optical systems. In this paper, we present schemes of information encoding and information hiding in the Airy pattern formed by diffraction of spatially coherent light after passing through a circular aperture. We propose a communication system that might be used to realize a new communication technique.

Yadav, Bharat K.; Bisht, N. S.; Mehrotra, R.; Kandpal, H. C.

2007-09-01

383

Precise extraction of the induced polarization in the {sup 4}He(e,e'p(pol){sup 3}H reaction.  

SciTech Connect

We measured with unprecedented precision the induced polarization P{sub y} in {sup 4}He(e,e'p(pol)){sup 3}H at Q{sup 2} = 0.8 and 1.3 (GeV/c){sup 2}. The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are overestimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin-independent charge-exchange term in the latter calculation.

Malace, S. P.; Paolone, M.; Strauch, S.; Albayrak, I.; Arrington, J.; Solvignon, P.; The E03-104 Collaboration (Physics); (Univ. of South Carolina); (Hampton Univ.)

2011-01-31

384

A precise extraction of the induced polarization in the 4He(e,e'p)3H reaction  

E-print Network

We measured with unprecedented precision the induced polarization Py in 4He(e,e'p)3H at Q^2 = 0.8 (GeV/c)^2 and 1.3 (GeV/c)^2. The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are over-estimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin independent charge-exchange term in the latter calculation.

S. P. Malace; M. Paolone; S. Strauch

2010-11-19

385

A precise extraction of the induced polarization in the 4He(e,e'p)3H reaction  

SciTech Connect

We measured with unprecedented precision the induced polarization Py in 4He(e,e'p)3H at Q^2 = 0.8 (GeV/c)^2 and 1.3 (GeV/c)^2. The induced polarization is indicative of reaction-mechanism effects beyond the impulse approximation. Our results are in agreement with a relativistic distorted-wave impulse approximation calculation but are over-estimated by a calculation with strong charge-exchange effects. Our data are used to constrain the strength of the spin independent charge-exchange term in the latter calculation.

S.P. Malace, M. Paolone, S. Strauch

2011-01-01

386

Reduction of polarization-induced artifacts in grating-based spectrometers  

Microsoft Academic Search

An optical device that converts unpolarized light into a single polarization state is described. The device is based on a polarizing beam splitter that separates the two polarization directions. The beam splitter is combined with two pairs of equilateral prisms that are used to collimate the two beams in terms of both propagation and polarization directions. When it is used

Kiang Wei Kho; Paul R. Stoddart; Gavan Rosman; Martin Harris; Alex Mazzolini

2005-01-01

387

Spectral and biological changes induced in nicotinic acid and related compounds by ultraviolet light  

PubMed Central

1. Irradiation of nicotinic acid, nicotinamide, nicotinamide N-oxide, N?-methyl-4-pyridone-3-carboxamide, reduced nicotinamide–adenine dinucleotide and pyridine with ultraviolet light at 253·7m? leads to striking spectral changes. 2. Nicotinic acid and nicotinamide are broken down to photosensitive intermediates which in turn undergo photodecomposition. 3. A major photoproduct of [7-14C]nicotinic acid is radioactive and absorbs ultraviolet light, but is inactive as a growth factor for Candida pseudotropicalis. 4. Irradiation of nicotinamide gives rise to small quantities of a biologically active photoproduct having the same RF as nicotinic acid. A second photoproduct is also formed, but its identity has not yet been established. 5. Irradiation of nicotinamide N-oxide leads to the formation of several photoproducts, one of which has the same RF as nicotinamide, absorbs ultraviolet light, and is biologically active. 6. Evidence is presented that irradiation of ethanolic solutions of N?-methyl-4-pyridone-3-carboxamide gives rise to acetaldehyde. 7. Irradiation of reduced nicotinamide–adenine dinucleotide in the presence of acetaldehyde leads to the formation of oxidized nicotinamide–adenine dinucleotide, which in turn can break down to nucleotide and/or nucleoside (depending on the conditions of the reaction). 8. The quantum yields of photolysis and the molar photosensitivities have been determined for N?-methyl-4-pyridone-3-carboxamide and nicotinamide N-oxide. 9. The possible biological significance of these photoreactions is discussed in relation to photosynthesis, visual-pigment metabolism and ultraviolet-light-induced cell damage. 10. A four-step theory is presented for the biochemical evolution of oxidation–reduction systems, involving photoactivated transformations of pyridine derivatives. ImagesFig. 3.Fig. 6. PMID:4285897

Abelson, Denis; Parthe, E.; Lee, K. W.; Boyle, A.

1965-01-01

388

The Cdc42/Par6/aPKC polarity complex regulates apoptosis-induced compensatory proliferation in epithelia  

PubMed Central

Summary Background In response to stress- or tissue damage-induced apoptosis, unaffected epithelial cells undergo compensatory proliferation to maintain the integrity of the epithelium. Proximal signals regulating this response are not fully appreciated, but JNK activity appears to be critical for both apoptosis and compensatory proliferation. Since disruption of epithelial cell apical-basal polarity, as can occur in early cancer development and is correlated with increased proliferation by means not fully characterized, we considered whether disruption of the various polarity complexes could provide signals identifying damaged epithelial cells, and thus lead to apoptosis-induced compensatory proliferation. Results We identify the Cdc42/Par6/aPKC Par polarity complex as uniquely and specifically regulating apoptosis-induced compensatory proliferation in Drosophila epithelia. Genetic depletion of individual components or disruption of complex formation and localization, but not other polarity complexes, induces JNK-dependent apoptosis and JNK-dependent compensatory proliferation following radiation injury. When apoptosis execution is blocked, by P35 expression, Cdc42/Par6/aPKC depleted tissues uniquely hyperproliferate leading to tissue/organ overgrowth. Disruption of Cdc42/Par6/aPKC leads to activation of JNK through increased Rho1-Rok activity, and Rok’s capacity to activate Myosin, but not F-actin. Conclusions We show that the Cdc42/Par6/aPKC polarity complex influences both a physiologic compensatory proliferation response after irradiation injury as well as a contrived compensatory non-cell autonomous hyperproliferation response when cell autonomous apoptosis, resulting from Cdc42/Par6/aPKC disruption, is inhibited. These results suggest the possibility that in cancer where apoptotic regulation is disrupted, loss of the Cdc42/Par6/aPKC polarity complex organization or localization could contribute to tumor hyperproliferation and explain how polarity disruption contributes to tumor development. PMID:20381350

Warner, Stephen J.; Yashiro, Hanako; Longmore, Gregory D.

2010-01-01

389

Focusing Sources on Induced Polarization and Electrical Resistivity Method Applied to Soil Pollution Problems  

NASA Astrophysics Data System (ADS)

In recent years the problems of soil contamination have been increasing and geophysical methods, particularly electrical resistivity tomography (ERT) have struggled to find and monitor cases of contamination. Moreover, Induced Polarization (IP) has shown promise in mapping contaminant plumes, although both techniques (ERT and IP) have problems like noise, inductive coupling, effects of electrodes, etc. limiting the precision and accuracy of the data. To overcome these problems, this paper introduces a novel technique of focusing sources. This technique reduces the effects of adjacent vertical formations and contacts due to the flowing of current in a vertical way at the zone where the electrode potentials have been deployed. This fact allows obtaining cleaner data of ERT and IP. In order to introduce the proposed technique a vertical contact synthetic model is studied and after to a cultivar area in Hidalgo State, México which presents different types of

Tejero, A.; Lopez, A.; Induced Polarization Team

2013-05-01

390

Ferroelectric polarization induces electric double layer bistability in electrolyte-gated field-effect transistors.  

PubMed

The dense surface charges expressed by a ferroelectric polymeric thin film induce ion displacement within a polyelectrolyte layer and vice versa. This is because the density of dipoles along the surface of the ferroelectric thin film and its polarization switching time matches that of the (Helmholtz) electric double layers formed at the ferroelectric/polyelectrolyte and polyelectrolyte/semiconductor interfaces. This combination of materials allows for introducing hysteresis effects in the capacitance of an electric double layer capacitor. The latter is advantageously used to control the charge accumulation in the semiconductor channel of an organic field-effect transistor. The resulting memory transistors can be written at a gate voltage of around 7 V and read out at a drain voltage as low as 50 mV. The technological implication of this large difference between write and read-out voltages lies in the non-destructive reading of this ferroelectric memory. PMID:24251907

Fabiano, Simone; Crispin, Xavier; Berggren, Magnus

2014-01-01

391

COMPLEX RESISTIVITY OF FAULT GOUGE AND ITS SIGNIFICANCE FOR EARTHQUAKE LIGHTS AND INDUCED POLARIZATION.  

USGS Publications Warehouse

The authors measured complex resistivity of 2 water-saturated San Andreas fault gouges from 10** minus **3 to 10**6 Hz and confining pressures of 0. 2 to 200 MPa. Consistent with earlier observations of clays and common rocks, large low-frequency permittivities were observed in all cases. Comparisons were made to induced polarization (IP) measurements by inversion of the data into the time domain, where it was found that principal features of the IP response curves were due to these large low-frequency permittivities. The results also suggest that following large earthquakes, significant electrical charge could remain for many seconds and could result in a variety of reported electromagnetic effects. Refs.

Lockner, David, A.; Byerlee, James, D.

1985-01-01

392

Magnetic-field-induced polarization and magnetocapacitance in quantum paraelectric EuTiO3  

NASA Astrophysics Data System (ADS)

EuTiO3 is a quantum paraelectric as well as an antiferromagnet. The most attractive property for EuTiO3 is the magnetoelectric coupling effect. In the present work, we investigate the influence of the external fields on EuTiO3, including the electric field E and magnetic field h. The application of the electric field counteracts the quantum fluctuation and forces the system into an electrically ordered state. The applied magnetic field directly induces the fluctuation of the spin-pair correlation and indirectly influences the dielectric behaviors through the magnetoelectric coupling. In addition, we notice that the contribution of the magnetic field depends closely on the temperature condition and the electric field background. The (p, h, E, T) and (, h, T) diagrams are presented showing the temperature, magnetic and electric field dependence of the polarization and the dielectric capacitance.

Gong, S. J.; Jiang, Q.

2004-11-01

393

High frequency magnetization rotation induced by a dc spin-polarized current in magnetic nanostructures  

NASA Astrophysics Data System (ADS)

While most recent studies of the spin-transfer torque effect in nanoscale magnetic structures mainly concern with spin-wave excitation and the magnetization hysteretic switching induced by spin-polarized current, we theoretically investigate the large angle magnetization precessions triggered and sustained by the spin current in great detail using the Landau-Lifshitz-Gilbert equation. The study is conducted particularly on the nanostructures comprising square magnets with an easy-plane anisotropy. A simple nanoscale magnetoelectronic device is proposed based on the structure without mechanical components to function as a motor to convert a dc current into an ac voltage of microwave frequency. The device is unique because the output amplitude and frequency can be continuously tuned by the electrical current in a wide range. Quantitative analysis of the device structure, function, and realization is provided.

Xi, Haiwen; Shi, Yiming

2004-08-01

394

Polarized linewidth-controllable double-trapping electromagnetically induced transparency spectra in a resonant plasmon nanocavity  

NASA Astrophysics Data System (ADS)

Surface plasmons with ultrasmall optical mode volume and strong near field enhancement can be used to realize nanoscale light-matter interaction. Combining surface plasmons with the quantum system provides the possibility of nanoscale realization of important quantum optical phenomena, including the electromagnetically induced transparency (EIT), which has many applications in nonlinear quantum optics and quantum information processing. Here, using a custom-designed resonant plasmon nanocavity, we demonstrate polarized position-dependent linewidth-controllable EIT spectra at the nanoscale. We analytically obtain the double coherent population trapping conditions in a double-? quantum system with crossing damping, which give two transparent points in the EIT spectra. The linewidths of the three peaks are extremely sensitive to the level spacing of the excited states, the Rabi frequencies and detunings of pump fields, and the Purcell factors. In particular the linewidth of the central peak is exceptionally narrow. The hybrid system may have potential applications in ultra-compact plasmon-quantum devices.

Wang, Luojia; Gu, Ying; Chen, Hongyi; Zhang, Jia-Yu; Cui, Yiping; Gerardot, Brian D.; Gong, Qihuang

2013-10-01

395

Spin-Exchange-Induced Circularly Polarized Molecular Fluorescence A. S. Green, G. A. Gallup, M. A. Rosenberry, and T. J. Gay  

E-print Network

Spin-Exchange-Induced Circularly Polarized Molecular Fluorescence A. S. Green, G. A. Gallup, M. A-0111, USA (Received 6 June 2003; published 1 March 2004) We have measured the circular polarization of light emitted from both atomic H and molecular H2 after bombarding H2 with longitudinally polarized electrons

Gay, Timothy J.

396

The X-ray spectrum and spectral energy distribution of FIRST J155633.8+351758: a LoBAL quasar with a probable polar outflow  

NASA Astrophysics Data System (ADS)

We report the results of a new 60 ks Chandra X-ray Observatory Advanced CCD Imaging Spectrometer S-array (ACIS-S) observation of the reddened, radio-selected, highly polarized `FeLoBAL' quasar FIRST J1556+3517. We investigated a number of models of varied sophistication to fit the 531-photon spectrum. These models ranged from simple power laws to power laws absorbed by hydrogen gas in differing ionization states and degrees of partial covering. Preferred fits indicate that the intrinsic X-ray flux is consistent with that expected for quasars of similarly high luminosity, i.e. an intrinsic, dereddened and unabsorbed optical to X-ray spectral index of -1.7. We cannot tightly constrain the intrinsic X-ray power-law slope, but find indications that it is flat (photon index ? = 1.7 or flatter at a >99 per cent confidence for a neutral hydrogen absorber model). Absorption is present, with a column density a few times 1023 cm-2, with both partially ionized models and partially covering neutral hydrogen models providing good fits. We present several lines of argument that suggest the fraction of X-ray emissions associated with the radio jet is not large. We combine our Chandra data with observations from the literature to construct the spectral energy distribution of FIRST J1556+3517 from radio to X-ray energies. We make corrections for Doppler beaming for the pole-on radio jet, optical dust reddening and X-ray absorption, in order to recover a probable intrinsic spectrum. The quasar FIRST J1556+3517 seems to be an intrinsically normal radio-quiet quasar with a reddened optical/UV spectrum, a Doppler-boosted but intrinsically weak radio jet and an X-ray absorber not dissimilar from that of other broad absorption line quasars.

Berrington, Robert C.; Brotherton, Michael S.; Gallagher, Sarah C.; Ganguly, Rajib; Shang, Zhaohui; DiPompeo, Michael; Chatterjee, Ritaban; Lacy, Mark; Gregg, Michael D.; Hall, Patrick B.; Laurent-Muehleisen, S. A.

2013-12-01

397

Field Trials of the Multi-Source Approach for Resistivity and Induced Polarization Data Acquisition  

NASA Astrophysics Data System (ADS)

Implementing systems of distributed receivers and transmitters for resistivity and induced polarization data is an almost inevitable result of the availability of wireless data communication modules and GPS modules offering precise timing and instrument locations. Such systems have a number of advantages; for example, they can be deployed around obstacles such as rivers, canyons, or mountains which would be difficult with traditional 'hard-wired' systems. However, deploying a system of identical, small, battery powered, transceivers, each capable of injecting a known current and measuring the induced potential has an additional and less obvious advantage in that multiple units can inject current simultaneously. The original purpose for using multiple simultaneous current sources (multi-source) was to increase signal levels. In traditional systems, to double the received signal you inject twice the current which requires you to apply twice the voltage and thus four times the power. Alternatively, one approach to increasing signal levels for large-scale surveys collected using small, battery powered transceivers is it to allow multiple units to transmit in parallel. In theory, using four 400 watt transmitters on separate, parallel dipoles yields roughly the same signal as a single 6400 watt transmitter. Furthermore, implementing the multi-source approach creates the opportunity to apply more complex current flow patterns than simple, parallel dipoles. For a perfect, noise-free system, multi-sources adds no new information to a data set that contains a comprehensive set of data collected using single sources. However, for realistic, noisy systems, it appears that multi-source data can substantially impact survey results. In preliminary model studies, the multi-source data produced such startling improvements in subsurface images that even the authors questioned their veracity. Between December of 2012 and July of 2013, we completed multi-source surveys at five sites with depths of exploration ranging from 150 to 450 m. The sites included shallow geothermal sites near Reno Nevada, Pomarance Italy, and Volterra Italy; a mineral exploration site near Timmins Quebec; and a landslide investigation near Vajont Dam in northern Italy. These sites provided a series of challenges in survey design and deployment including some extremely difficult terrain and a broad range of background resistivity and induced values. Despite these challenges, comparison of multi-source results to resistivity and induced polarization data collection with more traditional methods support the thesis that the multi-source approach is capable of providing substantial improvements in both depth of penetration and resolution over conventional approaches.

LaBrecque, D. J.; Morelli, G.; Fischanger, F.; Lamoureux, P.; Brigham, R.

2013-12-01

398

Multi-vortical flow inducing electrokinetic instability in ion concentration polarization layer  

NASA Astrophysics Data System (ADS)

In this work, we investigated multiple vortical flows inside the ion concentration polarization (ICP) layer that forms due to a coupling of applied electric fields and the semipermeable nanoporous junction between microchannels. While only a primary vortex near perm-selective membrane is traditionally known to lead to electrokinetic instability, multiple vortexes induced by the primary vortex were found to play a major role in the electrokinetic instability. The existence of multiple vortexes was directly confirmed by experiments using particle tracers and interdigitated electrodes were used to measure the local concentration profile inside the ICP layer. At larger applied electric fields, we observed aperiodic fluid motion due to electrokinetic instabilities which develop from a coupling of applied electric fields and electrical conductivity gradients induced by the ICP. The electrokinetic instability at micro-nanofluidic interfaces is important in the development of various electro-chemical-mechanical applications such as fuel cells, bio-analytical preconcentration methods, water purification/desalination and the fundamental study of ion electromigration through nanochannels and nonporous perm-selective membranes.In this work, we investigated multiple vortical flows inside the ion concentration polarization (ICP) layer that forms due to a coupling of applied electric fields and the semipermeable nanoporous junction between microchannels. While only a primary vortex near perm-selective membrane is traditionally known to lead to electrokinetic instability, multiple vortexes induced by the primary vortex were found to play a major role in the electrokinetic instability. The existence of multiple vortexes was directly confirmed by experiments using particle tracers and interdigitated electrodes were used to measure the local concentration profile inside the ICP layer. At larger applied electric fields, we observed aperiodic fluid motion due to electrokinetic instabilities which develop from a coupling of applied electric fields and electrical conductivity gradients induced by the ICP. The electrokinetic instability at micro-nanofluidic interfaces is important in the development of various electro-chemical-mechanical applications such as fuel cells, bio-analytical preconcentration methods, water purification/desalination and the fundamental study of ion electromigration through nanochannels and nonporous perm-selective membranes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32467a

Kim, Sung Jae; Ko, Sung Hee; Kwak, Rhokyun; Posner, Jonathan D.; Kang, Kwan Hyoung; Han, Jongyoon

2012-11-01

399

Frequency-induced polarization bistability in vertical-cavity surface-emitting lasers with orthogonal optical injection  

SciTech Connect

We report theoretically on a pure frequency-induced polarization bistability in a vertical-cavity surface-emitting laser (VCSEL) subject to orthogonal optical injection, i.e., the master laser light polarization is orthogonal to that of the slave VCSEL. As the frequency detuning is scanned from negative to positive values and for a fixed injected power, the VCSEL exhibits two successive and possibly bistable polarization switchings. The first switching (from the slave laser polarization to the injected light polarization) exhibits a bistable region whose width is maximum for a given value of the injected power. Such a dependency of hysteresis width on the injected power is similar to that recently found experimentally by Hong et al.[Electron. Lett. 36, 2019 (2000)]. The bistability accompanying the second switching (from the injected light polarization back to the slave laser free-running polarization) exhibits, however, significantly different features related to the occurrence of optical chaos. Interestingly, the width of the bistable region can be tuned over a large range not only by modifying the injection parameters but also by modifying the device parameters, in particular the VCSEL linewidth enhancement factor.

Gatare, I. [Supelec, LMOPS CNRS UMR-7132, Unite de Recherche Commune Supelec et Universite de Metz, Rue Edouard Belin 2, F-57070 Metz (France); Department of Applied Physics and Photonics, (TW-TONA), Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussels (Belgium); Panajotov, K. [Department of Applied Physics and Photonics, (TW-TONA), Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussels (Belgium); Sciamanna, M. [Supelec, LMOPS CNRS UMR-7132, Unite de Recherche Commune Supelec et Universite de Metz, Rue Edouard Belin 2, F-57070 Metz (France)

2007-02-15

400

Azimuthally polarized laser mode generation by multilayer mirror with wideband grating-induced TM leakage in the TE stopband.  

PubMed

A new intracavity laser polarization-mode selection scheme relying upon a TE/TM diffractive dichroism principle in a grating multilayer mirror is proposed and demonstrated. The grating diffracts the first orders between the TE and TM band edges of the angular spectra of the laser mirror inducing a leakage of the TM polarization into the mirror substrate through the multilayer stack whereas TE diffraction into the substrate is forbidden. This mechanism is non-resonant, thus relatively wide-band. Applied with a circular-line grating in the 1.0 µm - 1.1 µm wavelength range, this mirror filters out the radially polarization mode and causes the emission of the azimuthally polarized mode. An original amorphous silicon grating technology was developed and the optical function demonstrated in a Nd:YAG laser. PMID:22418346

Kämpfe, Thomas; Tonchev, Svetlen; Tishchenko, Alexandre V; Gergov, Deyan; Parriaux, Olivier

2012-02-27

401

The mechanism for continuum polarization in laser induced breakdown spectroscopy of Si(111)  

NASA Astrophysics Data System (ADS)

Polarization of the plasma luminescence produced by both nanosecond and femtosecond laser ablation of Si(111) was analyzed under different conditions of fluence and detection geometry. It is shown that the luminescence is partially polarized and is directed in the plane of the crystal. The time evolution of the plasma emission signal was also investigated with the use of a streak camera. The mechanism for polarization is proposed to be preferential reflection of s-polarized light (i.e., light polarized normal to the plane of laser incidence) by the melted surface, in agreement with the Fresnel equations. Earlier reports of much stronger polarization are shown to be erroneous.

Penczak, John S., Jr.; Liu, Yaoming; Schaller, Richard D.; Rich, Daniel H.; Gordon, Robert J.

2012-08-01

402

PHYSICAL REVIEW B 84, 155319 (2011) Nonequilibrium nuclear polarization and induced hyperfine and dipolar magnetic fields in  

E-print Network

PHYSICAL REVIEW B 84, 155319 (2011) Nonequilibrium nuclear polarization and induced hyperfine Department of Physics and Astronomy, California State University, Fullerton, California 92835, USA 2 Department of Physics and Astronomy and Optical Science and Technology Center, University of Iowa, Iowa City

Flatte, Michael E.

403

Temperature dependence of carrier spin polarization determined from current-induced domain wall motion in a Co/Ni nanowire  

SciTech Connect

We have investigated the temperature dependence of the current-induced magnetic domain wall (DW) motion in a perpendicularly magnetized Co/Ni nanowire at various temperatures and with various applied currents. The carrier spin polarization was estimated from the measured domain wall velocity. We found that it decreased more with increasing temperature from 100 K to 530 K than the saturation magnetization did.

Ueda, K.; Koyama, T.; Hiramatsu, R.; Kobayashi, K.; Ono, T. [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Chiba, D. [Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho Kawaguchi, Saitama 322-0012 (Japan); Fukami, S. [Green Innovation Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501 (Japan); Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Tanigawa, H.; Suzuki, T. [RENESAS Electronics Corporation, Sagamihara, Kanagawa 252-5298 (Japan); Ohshima, N. [NEC Energy Device Ltd., 1120 Shimokuzawa, Chuo-ku, Sagamihara, Kanagawa 252-5298 (Japan); Ishiwata, N. [Green Innovation Research Laboratories, NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8501 (Japan); Nakatani, Y. [University of Electro-communications, Chofu, Tokyo 182-8585 (Japan)

2012-05-14

404

Inducing spin polarization in carbon materials by introducing magnetic adsorbates—Fe 2 on a planar C 10  

NASA Astrophysics Data System (ADS)

Here, we consider a nanoscale material made from two Fe atoms sitting on a planar C 10 cluster. Based on the density functional theory, we demonstrate how it is feasible to induce spin polarization on an initially non-magnetic carbon material by introducing magnetic adsorbates.

Diño, Wilson Agerico; Muhida, Rifki; Arboleda, Nelson; Nakanishi, Hiroshi; Kasai, Hideaki

2004-05-01

405

Fungal Proteases Induce Th2 Polarization through Limited Dendritic Cell Maturation and Reduced Production of IL12  

Microsoft Academic Search

Allergens are capable of polarizing the T cell immune response toward a Th2 cytokine profile in a process that is mediated by dendritic cells (DCs). Proteases derived from Aspergillus species (Aspergillus proteases; AP) have been shown to induce a Th2-like immune response when administered directly to the airway and without adjuvant or prior priming immunizations at sites remote from the

Salah-Eddine Lamhamedi-Cherradi; Rachel Elizabeth Martin; Tomoki Ito; Farrah Kheradmand; David Brian Corry; Yong-Jun Liu; Matthew Moyle

406

Agonist-induced polarized trafficking and surface expression of the adenosine 2b receptor in intestinal epithelial cells: role of SNARE proteins  

E-print Network

Agonist-induced polarized trafficking and surface expression of the adenosine 2b receptor-induced polarized trafficking and surface expres- sion of the adenosine 2b receptor in intestinal epithelial cells July 15, 2004; doi:10.1152/ ajpgi.00164.2004.--Adenosine, acting through the A2b receptor, in- duces

Hall, Randy A

407

Enhanced inline conversion of fiber Bragg grating spectra based on increased polarization controllability  

NASA Astrophysics Data System (ADS)

We have demonstrated enhanced spectral conversion of a fiber Bragg grating (FBG) incorporating a polarization-diversity loop configuration (PDLC) with increased degree of freedom (DOF) in polarization control through the addition of wave plates. The proposed apparatus for spectral conversion consists of a four-port polarization beam splitter for constructing the PDLC, an FBG, and three wave plates including one half-wave and two quarter-wave plates. In the previous study using only two wave plates, slight birefringence of single-mode fibers connecting optical elements within the polarization-diversity loop induced random changes of states of polarization (SOPs), resulting in the spectral degradation. In this approach, the increased number of wave plates could complement it by providing a higher DOF in controlling SOPs and significantly improve spectral performances of the fabricated filter such as an insertion loss, side-mode suppression ratio, and band-rejection ratio.

Jang, Wook; Sung Koo, Ja; Wan Lee, Yong; Oh, Junghwan; Wook Lee, Yong

2013-04-01

408

Dynamically induced hemispheric differences in the seasonal evolution of the summer polar mesopause  

NASA Astrophysics Data System (ADS)

We analyze the seasonal cycle of the summer polar mesopause with regard to Interhemispheric and Intrahemispheric Coupling. Our basis is a long-term simulation with a new middle atmosphere GCM of intermediate complexity, including an explicit calculation of the radiation budget and the tropospheric moisture cycle. Hemispheric differences are solely induced by different tropospheric surface conditions (orography and land-sea contrasts). In particular, the prescribed stratospheric ozone and the solar insolation are assumed to be equivalent for both hemispheres. The same holds for the launch level parameters of non-orographic gravity waves. With this setup we find a pronounced hemispheric asymmetry in the seasonal evolution of the summer mesopause. This can be traced back to hemispheric differences in tropospheric planetary waves and its subsequent effects on temperature, zonal wind, and gravity-wave breaking in the middle atmosphere. The consequences are that, prior to solstice, the southern summer mesopause is higher than its northern hemispheric counterpart which is caused by Intrahemispheric Coupling. After solstice, the southern summer mesopause is warmer and at a lower altitude when compared to the corresponding situation in the northern hemisphere. This difference results from Interhemispheric Coupling. The simulated hemispheric differences correspond to recent ground-based temperature measurements at Antarctica in comparison to corresponding data from the northern hemisphere. Since complex climate models that resolve the MLT are not necessarily consistent with the observed hemispheric asymmetry, it is tempting to assume that different launch level parameters of extratropical non-orographic gravity waves need to be considered for the two hemispheres. One hint in this direction is obtained from the present model if we take the annual variation of the solar constant into account. Then the launch spectrum needs to be shifted to higher frequencies in the southern hemisphere in order to reproduce the hemispheric differences in the seasonal evolution of the summer polar mesopause.

Becker, Erich; Luebken, Franz-Josef; Knoepfel, Rahel

409

Errors induced by the neglect of polarization in radiance calculations for Rayleigh-scattering atmospheres  

NASA Technical Reports Server (NTRS)

Although neglecting polarization and replacing the rigorous vector radiative transfer equation by its approximate scalar counterpart has no physical background, it is a widely used simplification when the incident light is unpolarized and only the intensity of the reflected light is to be computed. We employ accurate vector and scalar multiple-scattering calculations to perform a systematic study of the errors induced by the neglect of polarization in radiance calculations for a homogeneous, plane-parallel Rayleigh-scattering atmosphere (with and without depolarization) above a Lambertian surface. Specifically, we calculate percent errors in the reflected intensity for various directions of light incidence and reflection, optical thicknesses of the atmosphere, single-scattering albedos, depolarization factors, and surface albedos. The numerical data displayed can be used to decide whether or not the scalar approximation may be employed depending on the parameters of the problem. We show that the errors decrease with increasing depolarization factor and/or increasing surface albedo. For conservative or nearly conservative scattering and small surface albedos, the errors are maximum at optical thicknesses of about 1. The calculated errors may be too large for some practical applications, and, therefore, rigorous vector calculations should be employed whenever possible. However, if approximate scalar calculations are used, we recommend to avoid geometries involving phase angles equal or close to 0 deg and 90 deg, where the errors are especially significant. We propose a theoretical explanation of the large vector/scalar differences in the case of Rayleigh scattering. According to this explanation, the differences are caused by the particular structure of the Rayleigh scattering matrix and come from lower-order (except first-order) light scattering paths involving right scattering angles and right-angle rotations of the scattering plane.

Mishchenko, M. I.; Lacis, A. A.; Travis, L. D.

1994-01-01

410

Identification of Genes Required for Normal Pheromone-Induced Cell ~ Polarization in Saccharomyces cerevisiae  

Microsoft Academic Search

ABSTRACT In response to mating pheromones, cells of the yeast Saccharomyces cerevisiae adopt a polarized “shmoo” morphology, in which the cytoskeleton and proteins involved in mating are localized to a cell- surface projection. This polarization , yet to be determined. We discuss the possible roles of these gene products in establishing cell polarity during mating. M ANY cell types generate

Janet Chenevert; Nicole Val; Ira Herskowitz

411

Cirrus induced polarization in 122 GHz aura Microwave Limb Sounder radiances  

Microsoft Academic Search

Previous simulation studies have outlined the possibility of significant polarization signals in microwave limb sounding due to horizontally aligned ice crystals in cirrus clouds. From the recently launched Aura MLS instrument, we present the first polarized microwave limb sounding observations of cirrus clouds. We also present polarized radiative transfer simulations, which show qualitative agreement with these observations, and indicate the

C. P. Davis; D. L. Wu; C. Emde; J. H. Jiang; R. E. Cofield; R. S. Harwood

2005-01-01

412

Cirrus induced polarization in 122 GHz aura Microwave Limb Sounder radiances  

Microsoft Academic Search

(1) Previous simulation studies have outlined the possibility of significant polarization signals in microwave limb sounding due to horizontally aligned ice crystals in cirrus clouds. From the recently launched Aura MLS instrument, we present the first polarized microwave limb sounding observations of cirrus clouds. We also present polarized radiative transfer simulations, which show qualitative agreement with these observations, and indicate

C. P. Davis; D. L. Wu; C. Emde; J. H. Jiang; R. E. Cofield; R. S. Harwood

2005-01-01

413

Vector photochromism in polarization-sensitive materials.  

PubMed

The phenomenon of vector photochromism was observed in some high-efficient polarization-sensitive materials depending on the radiant exposure of the inducing linearly polarized actinic light. The phenomenon has the purely vector nature because the absorption of the irradiated and unirradiated areas of the material is practically identical when we use unpolarized probing light. However, an essential change in the absorption spectrum was observed under probing the sample by linearly polarized nonactinic light when it passes through an analyzer, and this change depends on the value of radiant exposure. The kinetics of the photoanisotropy induced by linearly polarized actinic light at 457 nm was studied in case of wavelengths of 532 and 635 nm of the probing beam. The noticeable difference in absorbance was observed with increase in radiant exposure from 60??J/cm² up to 250??J/cm² for the used wavelengths of the probing beam. The experimental results obtained in polarization-sensitive material based on the ammonium salt of the azodye Mordant pure yellow in a gelatin matrix are presented. The dependence of the effective anisotropy on the material thickness has been investigated. The mechanism of the phenomenon is discussed. The observed effect can be used for creating dynamic polarization spectral filters controlled by light and the spectrally selective dynamic polarization holographic gratings. PMID:24978751

Chaganava, Irakli; Kakauridze, George; Kilosanidze, Barbara; Mshvenieradze, Yuri

2014-07-01

414

GAMMA-RAY POLARIZATION INDUCED BY COLD ELECTRONS VIA COMPTON PROCESSES  

SciTech Connect

The polarization measurement is an important tool to probe the prompt emission mechanism in gamma-ray bursts (GRBs). The synchrotron photons can be scattered by cold electrons in the outflow via Compton scattering (CS) processes. The observed polarization depends on both the photon energy and the viewing angle. With the typical bulk Lorentz factor {Gamma} {approx} 200, photons with energy E > 10 MeV tend to have smaller polarization than photons with energy E < 1 MeV. At the right viewing angle, i.e., {theta} {approx} {Gamma}{sup -1}, the polarization achieves its maximal value, and the polarization angle changes 90 Degree-Sign relative to the initial polarization direction. Thus, the synchrotron radiation plus CS model can naturally explain the 90 Degree-Sign change of the polarization angle in GRB 100826A.

Chang Zhe; Jiang Yunguo; Lin Hainan, E-mail: changz@ihep.ac.cn, E-mail: jiangyg@ihep.ac.cn, E-mail: linhn@ihep.ac.cn [Institute of High Energy Physics, Chinese Academy of Sciences, 100049 Beijing (China)

2013-05-20

415

Investigation of the field-induced ferromagnetic phase transition in spin polarized neutron matter: a lowest order constrained variational approach  

E-print Network

In this paper, the lowest order constrained variational (LOCV) method has been used to investigate the magnetic properties of spin polarized neutron matter in the presence of strong magnetic field at zero temperature employing $AV_{18}$ potential. Our results indicate that a ferromagnetic phase transition is induced by a strong magnetic field with strength greater than $10^{18}\\ G$, leading to a partial spin polarization of the neutron matter. It is also shown that the equation of state of neutron matter in the presence of magnetic field is stiffer than the case in absence of magnetic field.

G. H. Bordbar; Z. Rezaei; Afshin Montakhab

2011-03-18

416

Magnetic-field-induced ferroelectric polarization reversal in the multiferroic Ge(1-x)Mn(x)Te semiconductor.  

PubMed

Ge(1-x)Mn(x)Te is shown to be a multiferroic semiconductor, exhibiting both ferromagnetic and ferroelectric properties. By ferromagnetic resonance we demonstrate that both types of order are coupled to each other. As a result, magnetic-field-induced ferroelectric polarization reversal is achieved. Switching of the spontaneous electric dipole moment is monitored by changes in the magnetocrystalline anisotropy. This also reveals that the ferroelectric polarization reversal is accompanied by a reorientation of the hard and easy magnetization axes. By tuning the GeMnTe composition, the interplay between ferromagnetism and ferroelectricity can be controlled. PMID:24580486

Przybyli?ska, H; Springholz, G; Lechner, R T; Hassan, M; Wegscheider, M; Jantsch, W; Bauer, G

2014-01-31

417

Large ferroelectric polarization in the new double perovskite NaLaMnWO$_{6}$ induced by non-polar instabilities  

E-print Network

Based on density functional theory calculations and group theoretical analysis, we have studied NaLaMnWO$_{6}$ compound which has been recently synthesized [Phys. Rev. B 79, 224428 (2009)] and belongs to the $AA'BB'{\\rm O}_{6}$ family of double perovskites. At low temperature, the structure has monoclinic $P2_{1}$ symmetry, with layered ordering of the Na and La ions and rocksalt ordering of Mn and W ions. The Mn atoms show an antiferromagnetic (AFM) collinear spin ordering, and the compound has been reported as a potential multiferroic. By comparing the low symmetry structure with a parent phase of $P4/nmm$ symmetry, two distortion modes are found dominant. They correspond to MnO$_{6}$ and WO$_{6}$ octahedron \\textit{tilt} modes, often found in many simple perovskites. While in the latter these common tilting instabilities yield non-polar phases, in NaLaMnWO$_{6}$ the additional presence of the $A$-$A^{'}$ cation ordering is sufficient to make these rigid unit modes as a source of the ferroelectricity. Throu...

Fukushima, T; Picozzi, S; Perez-Mato, J M

2011-01-01

418

A photochemically induced dynamic nuclear polarization study of denatured states of lysozyme  

SciTech Connect

Photochemically induced dynamic nuclear polarization (photo-CIDNP) techniques have been used to examine denatured states of lysozyme produced under a variety of conditions. {sup 1}H CIDNP difference spectra of lysozyme denatured thermally, by the addition of 10 M urea, or by the complete reduction of its four disulfide bonds were found to differ substantially not only from the spectrum of the native protein but also from that expected for a completely unstructured polypeptide chain. Specifically, denatured lysozyme showed a much reduced enhancement of tryptophan relative to tyrosine than did a mixture of blocked amino acids with the same composition as the intact protein. By contrast, the CIDNP spectrum of lysozyme denatured in dimethyl sulfoxide solution was found to be similar to that expected for a random coil. It is proposed that nonrandom hydrophobic interactions are present within the denatured states of lysozyme in aqueous solution and that these reduce the reactivity of tryptophan residues relative to tyrosine residues. Characterization of such interactions is likely to be of considerable significance for an understanding of the process of protein folding.

Broadhurst, R.W.; Dobson, C.M.; Hore, P.J.; Radford, S.E.; Rees, M.L. (Univ. of Oxford (United Kingdom))

1991-01-01

419

Polarized linewidth-controllable double-trapping electromagnetically induced transparency spectra in a resonant plasmon nanocavity.  

PubMed

Surface plasmons with ultrasmall optical mode volume and strong near field enhancement can be used to realize nanoscale light-matter interaction. Combining surface plasmons with the quantum system provides the possibility of nanoscale realization of important quantum optical phenomena, including the electromagnetically induced transparency (EIT), which has many applications in nonlinear quantum optics and quantum information processing. Here, using a custom-designed resonant plasmon nanocavity, we demonstrate polarized position-dependent linewidth-controllable EIT spectra at the nanoscale. We analytically obtain the double coherent population trapping conditions in a double-? quantum system with crossing damping, which give two transparent points in the EIT spectra. The linewidths of the three peaks are extremely sensitive to the level spacing of the excited states, the Rabi frequencies and detunings of pump fields, and the Purcell factors. In particular the linewidth of the central peak is exceptionally narrow. The hybrid system may have potential applications in ultra-compact plasmon-quantum devices. PMID:24096943

Wang, Luojia; Gu, Ying; Chen, Hongyi; Zhang, Jia-Yu; Cui, Yiping; Gerardot, Brian D; Gong, Qihuang

2013-01-01

420

Polarized linewidth-controllable double-trapping electromagnetically induced transparency spectra in a resonant plasmon nanocavity  

PubMed Central

Surface plasmons with ultrasmall optical mode volume and strong near field enhancement can be used to realize nanoscale light-matter interaction. Combining surface plasmons with the quantum system provides the possibility of nanoscale realization of important quantum optical phenomena, including the electromagnetically induced transparency (EIT), which has many applications in nonlinear quantum optics and quantum information processing. Here, using a custom-designed resonant plasmon nanocavity, we demonstrate polarized position-dependent linewidth-controllable EIT spectra at the nanoscale. We analytically obtain the double coherent population trapping conditions in a double-? quantum system with crossing damping, which give two transparent points in the EIT spectra. The linewidths of the three peaks are extremely sensitive to the level spacing of the excited states, the Rabi frequencies and detunings of pump fields, and the Purcell factors. In particular the linewidth of the central peak is exceptionally narrow. The hybrid system may have potential applications in ultra-compact plasmon-quantum devices. PMID:24096943

Wang, Luojia; Gu, Ying; Chen, Hongyi; Zhang, Jia-Yu; Cui, Yiping; Gerardot, Brian D.; Gong, Qihuang

2013-01-01

421

Subsidence-induced methane clouds in Titan's winter polar stratosphere and upper troposphere  

NASA Astrophysics Data System (ADS)

Titan's atmospheric methane most likely originates from lakes at the surface and subsurface reservoirs. Accordingly, it has been commonly assumed that Titan's tropopause region, where the vertical temperature profile is a minimum, acts as a cold trap for convecting methane, leading to the expectation that the formation of methane clouds in Titan's stratosphere would be rare. The additional assumption that Titan's tropopause temperatures are independent of latitude is also required. However, Cassini Composite InfraRed Spectrometer (CIRS) and Radio Science Subsystem (RSS) data sets reveal colder temperatures in Titan's tropopause region near the winter pole than those at low latitudes and in the summer hemisphere. This, combined with the presence of a cross-equatorial meridional circulation with winter polar subsidence, as suggested by current general circulation models, implies the inevitable formation of Subsidence-Induced Methane Clouds (SIMCs) over Titan's winter pole. We verified this by retrieving the stratospheric methane mole fraction at 70°N from the strength of the far infrared methane pure rotation lines observed by CIRS and by assuming the RSS-derived thermal profile at 74.1°N. Our retrieved methane mole fraction of 1.50 ± 0.15% allows for methane to condense and form SIMCs at altitudes between ?48 and ?20 km. Radiative transfer analyses of a color composite image obtained by the Cassini Visible and Infrared Mapping Spectrometer (VIMS) during northern winter appear to corroborate the existence of these clouds.

Anderson, C. M.; Samuelson, R. E.; Achterberg, R. K.; Barnes, J. W.; Flasar, F. M.

2014-11-01

422

FLIM and emission spectral analysis of caspase-3 activation inside single living cell during anticancer drug-induced cell death  

Microsoft Academic Search

Two-photon excitation (TPE) fluorescence lifetime imaging microscopy (FLIM) and emission spectral imaging (ESI) are powerful\\u000a tools for fluorescence resonance energy transfer (FRET) measurement. In this study, we use these two techniques to analyze\\u000a caspase-3 activation inside single living cells during anticancer drug-induced human lung adenocarcinoma (ASTC-a-1) cell death.\\u000a TPE-ESI of SCAT3, a caspase-3 indicator based on FRET, was performed inside

Wenliang Pan; Junle Qu; Tongsheng Chen; Lei Sun; Jing Qi

2009-01-01

423

Application of the new comprehensive X-ray spectral model to the two brightest intermediate polars EX Hydrae and V1223 Sagittarii  

NASA Astrophysics Data System (ADS)

We applied the new comprehensive X-ray spectral model for the post-shock accretion column (PSAC) of the intermediate polars (IPs) constructed by Hayashi and Ishida to the Suzaku data of the two brightest IPs EX Hydrae and V1223 Sagittarii. The white dwarf (WD) mass and the specific accretion rate of EX Hya are estimated to be M_WD= 0.63_{-0.14}^{+0.17} M? and a=0.049_{-0.035}^{+0.66} g cm-2 s-1. Our WD mass of EX Hya is greater than that of previous X-ray estimations (˜0.4-0.5 M?), where higher specific accretion rate than ours is assumed, and marginally consistent with 0.790 ± 0.026 M? measured by Beuermann and Reinsch using a binary motion. On the other hand, with the aid of the PSAC height of V1223 Sgr hV1223 < 0.07RWD, we estimated M_WD= 0.87_{-0.06}^{+0.10} M_{?} and a > 2.0 g cm-2 s-1 for V1223 Sgr. We evaluated the fractional accreting area of EX Hya and V1223 Sgr at 0.0033_{-0.0030}^{+0.0067} and <0.007, respectively. Calculation of the hydrodynamical equations with these best-fitting parameters show that the PSAC height of EX Hya is 0.33 RWD = 2.8 × 108 cm. The maximum temperature of the EX Hya and V1223 Sgr are calculated at 18.0 keV and 43.1 keV, respectively. In EX Hya, the temperature distribution is flatter and the density at the top of the PSAC is smaller than those of the previous PSAC models because of its low specific accretion rate.

Hayashi, Takayuki; Ishida, Manabu

2014-07-01

424

Disorder-induced reversal of spin polarization in the Heusler alloy Co{sub 2}FeSi  

SciTech Connect

We study the spin polarization in the conduction band of Co{sub 2}FeSi layers with a different degree of structural order. The injected spin polarization in Co{sub 2}FeSi/(Al,Ga)As spin light-emitting diodes as well as the planar Hall effect measured for the Co{sub 2}FeSi injectors exhibit a sign reversal between injectors crystallized in the ordered L2{sub 1} phase and the Fe-Si disordered B2 phase. These results are explained by a disorder-induced change in the spin polarization at the Fermi energy of Co{sub 2}FeSi. Support for the occurrence of such a striking change in the electronic band structure is obtained by first principles calculations.

Bruski, P.; Ramsteiner, M.; Brandt, O.; Friedland, K.-J.; Farshchi, R.; Herfort, J.; Riechert, H. [Paul-Drude Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, D-10117 Berlin (Germany); Erwin, S. C. [Center for Computational Materials Science, Naval Research Laboratory, Washington, DC 20375 (United States)

2011-04-01

425

Parahydrogen-induced polarization transfer to 19F in perfluorocarbons for 19F?NMR spectroscopy and MRI.  

PubMed

Fluorinated substances are important in chemistry, industry, and the life sciences. In a new approach, parahydrogen-induced polarization (PHIP) is applied to enhance (19)F?MR signals of (perfluoro-n-hexyl)ethene and (perfluoro-n-hexyl)ethane. Unexpectedly, the end-standing CF3 group exhibits the highest amount of polarization despite the negligible coupling to the added protons. To clarify this non-intuitive distribution of polarization, signal enhancements in deuterated chloroform and acetone were compared and (19)F-(19)F?NOESY spectra, as well as (19)F T1 values were measured by NMR spectroscopy. By using the well separated and enhanced signal of the CF3 group, first (19)F?MR images of hyperpolarized linear semifluorinated alkenes were recorded. PMID:23526596

Plaumann, Markus; Bommerich, Ute; Trantzschel, Thomas; Lego, Denise; Dillenberger, Sonja; Sauer, Grit; Bargon, Joachim; Buntkowsky, Gerd; Bernarding, Johannes

2013-05-10

426

CTLA-4Ig immunotherapy of obesity-induced insulin resistance by manipulation of macrophage polarization in adipose tissues  

SciTech Connect

Highlights: •CTLA-4Ig completely alleviates HFD-induced insulin resistance. •CTLA-4Ig reduces epididymal and subcutaneous fat tissue weight and adipocyte size. •CTLA-4Ig alters ATM polarization from inflammatory M1 to anti-inflammatory M2. •CTLA-4Ig may lead to a novel anti-obesity/inflammation/insulin resistance agent. •We identified the mechanism of the novel favorable effects of CTLA-4lg. -- Abstract: It has been established that obesity alters the metabolic and endocrine function of adipose tissue and, together with accumulation of adipose tissue macrophages, contributes to insulin resistance. Although numerous studies have reported that shifting the polarization of macrophages from M1 to M2 can alleviate adipose tissue inflammation, manipulation of macrophage polarization has not been considered as a specific therapy. Here, we determined whether cytotoxic T-lymphocyte-associated antigen-4IgG1 (CTLA-4Ig) can ameliorate insulin resistance by induction of macrophages from proinflammatory M1 to anti-inflammatory M2 polarization in the adipose tissues of high fat diet-induced insulin-resistant mice. CTLA4-Ig treatment prevented insulin resistance by changing gene expression to M2 polarization, which increased the levels of arginase 1. Furthermore, flow cytometric analysis confirmed the alteration of polarization from CD11c (M1)- to CD206 (M2)-positive cells. Concomitantly, CTLA-4Ig treatment resulted in weight reductions of epididymal and subcutaneous adipose tissues, which may be closely related to overexpression of apoptosis inhibitors in macrophages. Moreover, proinflammatory cytokine and chemokine levels decreased significantly. In contrast, CCAAT enhancer binding protein ?, peroxisome proliferator-activated receptor ?, and adiponectin expression increased significantly in subcutaneous adipose tissue. This novel mechanism of CTLA-4lg immunotherapy may lead to an ideal anti-obesity/inflammation/insulin resistance agent.

Fujii, Masakazu, E-mail: masakazu731079@yahoo.co.jp [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan)] [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Inoguchi, Toyoshi, E-mail: toyoshi@intmed3.med.kyushu-u.ac.jp [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan) [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Innovation Center for Medical Redox Navigation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Batchuluun, Battsetseg, E-mail: battsetseg.batchuluun@gmail.com [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan)] [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Sugiyama, Naonobu, E-mail: nao1@intmed1.med.kyushu-u.ac.jp [Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan)] [Department of Medicine and Biosystemic Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Kobayashi, Kunihisa, E-mail: nihisak@fukuoka-u.ac.jp [Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, 1-1-1 Zokumyoin, Chikushino, Fukuoka 818-8502 (Japan)] [Department of Endocrinology and Diabetes Mellitus, Fukuoka University Chikushi Hospital, 1-1-1 Zokumyoin, Chikushino, Fukuoka 818-8502 (Japan); Sonoda, Noriyuki, E-mail: noriyuki@intmed3.med.kyushu-u.ac.jp [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan) [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Innovation Center for Medical Redox Navigation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan); Takayanagi, Ryoichi, E-mail: takayana@intmed3.med.kyushu-u.ac.jp [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan)] [Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582 (Japan)

2013-08-16

427

Generation of elliptically polarized terahertz waves from laser-induced plasma with double helix electrodes.  

PubMed

By applying a helical electric field along a plasma region, a revolving electron current is formed along the plasma and an elliptically polarized far-field terahertz wave pattern is observed. The observed terahertz wave polarization reveals the remarkable role of velocity retardation between optical pulses and generated terahertz pulses in the generation process. Extensive simulations, including longitudinal propagation effects, are performed to clarify the mechanisms responsible for polarization control of air-plasma-based terahertz sources. PMID:22540584

Lu, Xiaofei; Zhang, X-C

2012-03-23

428

Enhanced osteoconductivity of titanium implant by polarization-induced surface charges.  

PubMed

This study introduces the application of method for electrically polarizing titanium implants coated with anatase TiO2 using microarc oxidation. It also describes the features of the electrically polarized titanium implants, on which surface charges are generated by the dipole moment of the TiO2 , and describes how the surface charges affect the implants' in vivo bone-implant integration capability. A comprehensive assessment using biomechanical, histomorphological, and radiographic analyses in a rabbit model was performed on polarized and nonpolarized implants. The electrically polarized surfaces accelerated the establishment of implant biomechanical fixation, compared with the nonpolarized surfaces. The percentage of the bone-implant contact ratio was higher using polarized implants than using nonpolarized implants. In contrast, the bone volume around the implants was not affected by polarization. Thus, using the polarized implant, this study identified that controlled surface charges have a significant effect on the properties of titanium implants. The application of the electrical polarization process and the polarization-enhanced osteoinductivity, which resulted in greater bone-implant integration, was clearly demonstrated. PMID:24123807

Nozaki, Kosuke; Wang, Wei; Horiuchi, Naohiro; Nakamura, Miho; Takakuda, Kazuo; Yamashita, Kimihiro; Nagai, Akiko

2014-09-01

429

Infrared spectral measurements (450–2500 cm?1) of shuttle-induced optical contamination  

Microsoft Academic Search

The first shuttle-based infrared spectral measurements in the region beyond 800 nm were made during the STS-39 mission. A cryogenic Michelson interferometer in the CIRRIS-1A payload yielded high quality atmospheric IR spectra in the earthlimb observing mode. In addition, observations in the very high earthlimb and in the bay-to-space mode provided important opportunities to assess optical contamination. These observations have

D. K. Zhou; W. R. Pendleton; G. E. Bingham; A. J. Steed; D. A. Dean

1994-01-01

430

Infrared spectral measurements (450-2500\\/cm) of shuttle-induced optical contamination  

Microsoft Academic Search

The first shuttle-based infrared spectral measurements in the region beyond 800 nm were made during the STS-39 mission. A cryogenic Michelson interferometer in the Cryogenic Infrared Radiance Instrumentation for Shuttle (CIRRIS-1A) payload yielded high quality atmospheric IR spectra in the earthlimb observing mode. In addition, observations in the very high earthlimb and in the bay-to-space mode provided important opportunities to

D. K. Zhou; W. R. Pendleton Jr.; G. E. Bingham; A. J. Steed; D. A. Dean

1994-01-01

431

Thermally induced spectral drift cancellation in pressure-tuned Fabry-Perot etalons  

Microsoft Academic Search

The University of Wisconsin High Spectral Resolution Lidar (HSRL) employs several N2 pressure-tuned etalons to perform laser bandwidth restriction in the transmitter and bandpass shaping in the dual-channel receiver. System calibration requires knowledge of the envelope of the transmitted laser spectrum as viewed by the receiver. Thus, the calibration is highly sensitive to relative wavelength drift between the transmitter and

Christian J. Grund; F. L. Roesler; E. W. Eloranta

1988-01-01

432

Polarization-induced two-dimensional electron gas at Zn 1-xMg xO/ZnO heterointerface  

NASA Astrophysics Data System (ADS)

Spontaneous and piezoelectric polarizations, PSP and PPE, in the c-axis direction of Zn 1-xMg xO/ZnO heterostructures are estimated by analyzing the density of the two-dimensional electron gas (2DEG) accumulated at the interface. The experimental data on 2DEGs indicated that positive sheet charges responsible for the 2DEG accumulation were induced at the interface by the polarization with a proportional increase to the x in Zn 1-xMg xO barrier layer. For the samples grown on a-plane sapphire substrates by molecular beam epitaxy (MBE) , however, both of the PSP and PPE in a thin ZnO cap layer on thick Zn 1-xMg xO buffer layer were found to be negative due to the tensile-strained pseudomorphic growth in O polarity. Since negative polarization induces negative sheet charges at the Zn 1-xMg xO/ZnO interface, this result should indicate the larger contribution of the PSP discontinuity at Zn 1-xMg xO/ZnO interface than that of the PPE in ZnO cap layer, deducing the x-dependent PSP in Zn 1-xMg xO to be -(0.057+0.066 x) C/m 2. This interpretation is supported by the theoretical estimation of the PSP at Zn 0.5Mg 0.5O using a first-principals calculation.

Yano, Mitsuaki; Hashimoto, Kazuyuki; Fujimoto, Kazuya; Koike, Kazuto; Sasa, Shigehiko; Inoue, Masataka; Uetsuji, Yasutomo; Ohnishi, Tomoyuki; Inaba, Katsuhiko

2007-04-01

433

CTLA-4Ig immunotherapy of obesity-induced insulin resistance by manipulation of macrophage polarization in adipose tissues.  

PubMed

It has been established that obesity alters the metabolic and endocrine function of adipose tissue and, together with accumulation of adipose tissue macrophages, contributes to insulin resistance. Although numerous studies have reported that shifting the polarization of macrophages from M1 to M2 can alleviate adipose tissue inflammation, manipulation of macrophage polarization has not been considered as a specific therapy. Here, we determined whether cytotoxic T-lymphocyte-associated antigen-4IgG1 (CTLA-4Ig) can ameliorate insulin resistance by induction of macrophages from proinflammatory M1 to anti-inflammatory M2 polarization in the adipose tissues of high fat diet-induced insulin-resistant mice. CTLA4-Ig treatment prevented insulin resistance by changing gene expression to M2 polarization, which increased the levels of arginase 1. Furthermore, flow cytometric analysis confirmed the alteration of polarization from CD11c (M1)- to CD206 (M2)-positive cells. Concomitantly, CTLA-4Ig treatment resulted in weight reductions of epididymal and subcutaneous adipose tissues, which may be closely related to overexpression of apoptosis inhibitors in macrophages. Moreover, proinflammatory cytokine and chemokine levels decreased significantly. In contrast, CCAAT enhancer binding protein ?, peroxisome proliferator-activated receptor ?, and adiponectin expression increased significantly in subcutaneous adipose tissue. This novel mechanism of CTLA-4lg immunotherapy may lead to an ideal anti-obesity/inflammation/insulin resistance agent. PMID:23872146

Fujii, Masakazu; Inoguchi, Toyoshi; Batchuluun, Battsetseg; Sugiyama, Naonobu; Kobayashi, Kunihisa; Sonoda, Noriyuki; Takayanagi, Ryoichi

2013-08-16