Motion of dust in a planetary magnetosphere - Orbit-averaged equations for oblateness, electromagnetic, and radiation forces with application to Saturn's E ring

NASA Technical Reports Server (NTRS)

Hamilton, Douglas P.

1993-01-01

The orbital dynamics of micrometer-sized dust grains is explored numerically and analytically, treating the strongest perturbation forces acting on close circumplanetary dust grains: higher-order gravity, radiation pressure, and the electromagnetic force. The appropriate orbit-average equations are derived and applied to the E ring. Arguments are made for the existence of azimuthal and vertical asymmetries in the E ring. New understanding of the dynamics of E ring dust grains is applied to problems of the ring's breadth and height. The possibility for further ground-based and spacecraft observations is considered.

JLEIC SRF cavity RF Design

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

Wang, Shaoheng; Guo, Jiquan; Wang, Haipeng

2016-05-01

The initial design of a low higher order modes (HOM) impedance superconducting RF (SRF) cavity is presented in this paper. The design of this SRF cavity is for the proposed Jefferson Lab Electron Ion Collider (JLEIC). The electron ring of JLEIC will operate with electrons of 3 to 10 GeV energy. The ion ring of JLEIC will operate with protons of up to 100 GeV energy. The bunch lengths in both rings are ~12 mm (RMS). In order to maintain the short bunch length in the ion ring, SRF cavities are adopted to provide large enough gradient. In the firstmore » phase of JLEIC, the PEP II RF cavities will be reused in the electron ring to lower the initial cost. The frequency of the SRF cavities is chosen to be the second harmonic of PEP II cavities, 952.6 MHz. In the second phase of JLEIC, the same frequency SRF cavities may replace the normal conducting PEP II cavities to achieve higher luminosity at high energy. At low energies, the synchro-tron radiation damping effect is quite weak, to avoid the coupled bunch instability caused by the intense closely-spaced electron bunches, low HOM impedance of the SRF cavities combined with longitudinal feedback sys-tem will be necessary.« less

Accelerator structure and beam transport system for the KEK photon factory injector

NASA Astrophysics Data System (ADS)

Sato, Isamu

1980-11-01

The injector is a 2.5 GeV electron linac which serves multiple purposes, being not only the injector for the various storage rings of the Photon Factory but also for the next planned project, the TRISTAN RING, and also as an intense electron or γ-ray source for research on phenomena in widely diverse scientific fields. The accelerator structure and beam transport system for the linac were designed with the greatest care in order to avoid beam blow-up difficulties, and also to be as suitable as possible to enable the economical mass production of the accelerator guides and focusing magnets.

Application of combinatorial biocatalysis for a unique ring expansion of dihydroxymethylzearalenone.

PubMed

Rich, Joseph O; Budde, Cheryl L; McConeghey, Luke D; Cotterill, Ian C; Mozhaev, Vadim V; Singh, Sheo B; Goetz, Michael A; Zhao, Annie; Michels, Peter C; Khmelnitsky, Yuri L

2009-06-01

Combinatorial biocatalysis was applied to generate a diverse set of dihydroxymethylzearalenone analogs with modified ring structure. In one representative chemoenzymatic reaction sequence, dihydroxymethylzearalenone was first subjected to a unique enzyme-catalyzed oxidative ring opening reaction that creates two new carboxylic groups on the molecule. These groups served as reaction sites for further derivatization involving biocatalytic ring closure reactions with structurally diverse bifunctional reagents, including different diols and diamines. As a result, a library of cyclic bislactones and bislactams was created, with modified ring structures covering chemical space and structure activity relationships unattainable by conventional synthetic means.

Compact circularly polarized truncated square ring slot antenna with suppressed higher resonances

PubMed Central

Sabran, Mursyidul Idzam; Leow, Chee Yen; Soh, Ping Jack; Chew, Beng Wah; Vandenbosch, Guy A. E.

2017-01-01

This paper presents a compact circularly polarized (CP) antenna with an integrated higher order harmonic rejection filter. The proposed design operates within the ISM band of 2.32 GHz– 2.63 GHz and is suitable for example for wireless power transfer applications. Asymmetrical truncated edges on a square ring create a defected ground structure to excite the CP property, simultaneously realizing compactness. It offers a 50.5% reduced patch area compared to a conventional design. Novel stubs and slot shapes are integrated in the transmission line to reduce higher (up to the third) order harmonics. The proposed prototype yields a -10 dB reflection coefficient (S11) impedance bandwidth of 12.53%, a 3 dB axial ratio bandwidth of 3.27%, and a gain of 5.64 dBi. Measurements also show good agreement with simulations. PMID:28192504

Compact circularly polarized truncated square ring slot antenna with suppressed higher resonances.

PubMed

Sabran, Mursyidul Idzam; Abdul Rahim, Sharul Kamal; Leow, Chee Yen; Soh, Ping Jack; Chew, Beng Wah; Vandenbosch, Guy A E

2017-01-01

This paper presents a compact circularly polarized (CP) antenna with an integrated higher order harmonic rejection filter. The proposed design operates within the ISM band of 2.32 GHz- 2.63 GHz and is suitable for example for wireless power transfer applications. Asymmetrical truncated edges on a square ring create a defected ground structure to excite the CP property, simultaneously realizing compactness. It offers a 50.5% reduced patch area compared to a conventional design. Novel stubs and slot shapes are integrated in the transmission line to reduce higher (up to the third) order harmonics. The proposed prototype yields a -10 dB reflection coefficient (S11) impedance bandwidth of 12.53%, a 3 dB axial ratio bandwidth of 3.27%, and a gain of 5.64 dBi. Measurements also show good agreement with simulations.

Design and optimization of liquid core optical ring resonator for refractive index sensing.

PubMed

Lin, Nai; Jiang, Lan; Wang, Sumei; Xiao, Hai; Lu, Yongfeng; Tsai, Hai-Lung

2011-07-10

This study performs a detailed theoretical analysis of refractive index (RI) sensors based on whispering gallery modes (WGMs) in liquid core optical ring resonators (LCORRs). Both TE- and TM-polarized WGMs of various orders are considered. The analysis shows that WGMs of higher orders need thicker walls to achieve a near-zero thermal drift, but WGMs of different orders exhibit a similar RI sensing performance at the thermostable wall thicknesses. The RI detection limit is very low at the thermostable thickness. The theoretical predications should provide a general guidance in the development of LCORR-based thermostable RI sensors. © 2011 Optical Society of America

Planetary Rings

NASA Astrophysics Data System (ADS)

Esposito, Larry W.

2011-07-01

Preface; 1. Introduction: the allure of ringed planets; 2. Studies of planetary rings 1610-2004; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-Body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Neptune's partial rings; 13. Jupiter's ring-moon system after Galileo; 14. Ring photometry; 15. Dusty rings; 16. Cassini observations; 17. Summary: the big questions; Glossary; References; Index.

Contiguous metallic rings: an inductive mesh with high transmissivity, strong electromagnetic shielding, and uniformly distributed stray light.

PubMed

Tan, Jiubin; Lu, Zhengang

2007-02-05

This paper presents the experimental study on an inductive mesh composed of contiguous metallic rings fabricated using UV-lithography on quartz glass. Experimental results indicate that, at the same period and linewidth as square mesh, ring mesh has better transmissivity for its higher obscuration ratio, stronger electromagnetic shielding performance for its smaller maximum aperture, and less degradation of imaging quality for its lower ratio and uniform distribution of high order diffraction energy. It is therefore concluded that this kind of ring mesh can be used as high-pass filters to provide electromagnetic shielding of optical transparent elements.

Urban climate modifies tree growth in Berlin

NASA Astrophysics Data System (ADS)

Dahlhausen, Jens; Rötzer, Thomas; Biber, Peter; Uhl, Enno; Pretzsch, Hans

2017-12-01

Climate, e.g., air temperature and precipitation, differs strongly between urban and peripheral areas, which causes diverse life conditions for trees. In order to compare tree growth, we sampled in total 252 small-leaved lime trees (Tilia cordata Mill) in the city of Berlin along a gradient from the city center to the surroundings. By means of increment cores, we are able to trace back their growth for the last 50 to 100 years. A general growth trend can be shown by comparing recent basal area growth with estimates from extrapolating a growth function that had been fitted with growth data from earlier years. Estimating a linear model, we show that air temperature and precipitation significantly influence tree growth within the last 20 years. Under consideration of housing density, the results reveal that higher air temperature and less precipitation led to higher growth rates in high-dense areas, but not in low-dense areas. In addition, our data reveal a significantly higher variance of the ring width index in areas with medium housing density compared to low housing density, but no temporal trend. Transferring the results to forest stands, climate change is expected to lead to higher tree growth rates.

Urban climate modifies tree growth in Berlin

NASA Astrophysics Data System (ADS)

Dahlhausen, Jens; Rötzer, Thomas; Biber, Peter; Uhl, Enno; Pretzsch, Hans

2018-05-01

Climate, e.g., air temperature and precipitation, differs strongly between urban and peripheral areas, which causes diverse life conditions for trees. In order to compare tree growth, we sampled in total 252 small-leaved lime trees ( Tilia cordata Mill) in the city of Berlin along a gradient from the city center to the surroundings. By means of increment cores, we are able to trace back their growth for the last 50 to 100 years. A general growth trend can be shown by comparing recent basal area growth with estimates from extrapolating a growth function that had been fitted with growth data from earlier years. Estimating a linear model, we show that air temperature and precipitation significantly influence tree growth within the last 20 years. Under consideration of housing density, the results reveal that higher air temperature and less precipitation led to higher growth rates in high-dense areas, but not in low-dense areas. In addition, our data reveal a significantly higher variance of the ring width index in areas with medium housing density compared to low housing density, but no temporal trend. Transferring the results to forest stands, climate change is expected to lead to higher tree growth rates.

Urban climate modifies tree growth in Berlin.

PubMed

Dahlhausen, Jens; Rötzer, Thomas; Biber, Peter; Uhl, Enno; Pretzsch, Hans

2018-05-01

Climate, e.g., air temperature and precipitation, differs strongly between urban and peripheral areas, which causes diverse life conditions for trees. In order to compare tree growth, we sampled in total 252 small-leaved lime trees (Tilia cordata Mill) in the city of Berlin along a gradient from the city center to the surroundings. By means of increment cores, we are able to trace back their growth for the last 50 to 100 years. A general growth trend can be shown by comparing recent basal area growth with estimates from extrapolating a growth function that had been fitted with growth data from earlier years. Estimating a linear model, we show that air temperature and precipitation significantly influence tree growth within the last 20 years. Under consideration of housing density, the results reveal that higher air temperature and less precipitation led to higher growth rates in high-dense areas, but not in low-dense areas. In addition, our data reveal a significantly higher variance of the ring width index in areas with medium housing density compared to low housing density, but no temporal trend. Transferring the results to forest stands, climate change is expected to lead to higher tree growth rates.

Connections between Star Cluster Populations and Their Host Galaxy Nuclear Rings

NASA Astrophysics Data System (ADS)

Ma, Chao; de Grijs, Richard; Ho, Luis C.

2018-04-01

Nuclear rings are excellent laboratories for probing diverse phenomena such as the formation and evolution of young massive star clusters and nuclear starbursts, as well as the secular evolution and dynamics of their host galaxies. We have compiled a sample of 17 galaxies with nuclear rings, which are well resolved by high-resolution Hubble and Spitzer Space Telescope imaging. For each nuclear ring, we identified the ring star cluster population, along with their physical properties (ages, masses, and extinction values). We also determined the integrated ring properties, including the average age, total stellar mass, and current star formation rate (SFR). We find that Sb-type galaxies tend to have the highest ring stellar mass fraction with respect to the host galaxy, and this parameter is correlated with the ring’s SFR surface density. The ring SFRs are correlated with their stellar masses, which is reminiscent of the main sequence of star-forming galaxies. There are striking correlations between star-forming properties (i.e., SFR and SFR surface density) and nonaxisymmetric bar parameters, appearing to confirm previous inferences that strongly barred galaxies tend to have lower ring SFRs, although the ring star formation histories turn out to be significantly more complicated. Nuclear rings with higher stellar masses tend to be associated with lower cluster mass fractions, but there is no such relation for the ages of the rings. The two youngest nuclear rings in our sample, NGC 1512 and NGC 4314, which have the most extreme physical properties, represent the young extremity of the nuclear ring age distribution.

Planetary Rings

NASA Astrophysics Data System (ADS)

Esposito, Larry

2014-03-01

Preface: a personal view of planetary rings; 1. Introduction: the allure of the ringed planets; 2. Studies of planetary rings 1610-2013; 3. Diversity of planetary rings; 4. Individual ring particles and their collisions; 5. Large-scale ring evolution; 6. Moons confine and sculpt rings; 7. Explaining ring phenomena; 8. N-body simulations; 9. Stochastic models; 10. Age and evolution of rings; 11. Saturn's mysterious F ring; 12. Uranus' rings and moons; 13. Neptune's partial rings; 14. Jupiter's ring-moon system after Galileo and New Horizons; 15. Ring photometry; 16. Dusty rings; 17. Concluding remarks; Afterword; Glossary; References; Index.

Scaling of angiosperm xylem structure with safety and efficiency.

PubMed

Hacke, Uwe G; Sperry, John S; Wheeler, James K; Castro, Laura

2006-06-01

We tested the hypothesis that greater cavitation resistance correlates with less total inter-vessel pit area per vessel (the pit area hypothesis) and evaluated a trade-off between cavitation safety and transport efficiency. Fourteen species of diverse growth form (vine, ring- and diffuse-porous tree, shrub) and family affinity were added to published data predominately from the Rosaceae (29 species total). Two types of vulnerability-to-cavitation curves were found. Ring-porous trees and vines showed an abrupt drop in hydraulic conductivity with increasing negative pressure, whereas hydraulic conductivity in diffuse-porous species generally decreased gradually. The ring-porous type curve was not an artifact of the centrifuge method because it was obtained also with the air-injection technique. A safety versus efficiency trade-off was evident when curves were compared across species: for a given pressure, there was a limited range of optimal vulnerability curves. The pit area hypothesis was supported by a strong relationship (r2 = 0.77) between increasing cavitation resistance and diminishing pit membrane area per vessel (A(P)). Small A(P) was associated with small vessel surface area and hence narrow vessel diameter (D) and short vessel length (L)--consistent with an increase in vessel flow resistance with cavitation resistance. This trade-off was amplified at the tissue level by an increase in xylem/vessel area ratio with cavitation resistance. Ring-porous species were more efficient than diffuse-porous species on a vessel basis but not on a xylem basis owing to higher xylem/vessel area ratios in ring-porous anatomy. Across four orders of magnitude, lumen and end-wall resistivities maintained a relatively tight proportionality with a near-optimal mean of 56% of the total vessel resistivity residing in the end-wall. This was consistent with an underlying scaling of L to D(3/2) across species. Pit flow resistance did not increase with cavitation safety, suggesting that cavitation pressure was not related to mean pit membrane porosity.

Determination and source identification of priority polycyclic aromatic hydrocarbons in PM2.5 in Taiyuan, China

NASA Astrophysics Data System (ADS)

Zhang, Meng; Xie, Jingfang; Wang, Zhentao; Zhao, Lijuan; Zhang, Hong; Li, Meng

2016-09-01

Sixteen polycyclic aromatic hydrocarbons (PAHs) present in PM2. 5 were analyzed in 2012 in Taiyuan (China) using high performance liquid chromatography (HPLC) with fluorescence and ultraviolet detectors. The average daily mass concentrations of ΣPAHs in different seasons ranged from 10.36 ng/m3 to 215.93 ng/m3 and had strong seasonal variation, with highest values in winter and lowest in summer. Over the whole year, PAHs appeared in the following order of frequency: 4-ring > 6-ring > 5-ring > 3-ring; in winter, the percentage of 4-ring PAHs was the highest (62.68%), while in summer, the percentages of 5-ring and 6-ring PAHs (cumulative total of 50.57%) were higher. The ratio method was employed to investigate potential source categories of PAHs in PM2.5 in Taiyuan, with data suggesting that the main PAH sources are coal and wood combustion and vehicle emissions. Finally, a risk assessment of PAHs was performed based on benzo(a)pyrene equivalent (BaPeq) values and individual cancer risk ratios, with results suggesting that the toxicity of PAHs was high during winter and spring time in Taiyuan. The values of incremental lifetime cancer risk (ILCR) induced by whole year inhalation exposure(Ri) for all age groups were larger than 10- 6 in spring and winter, while Ri values for male and female adults in summer and autumn were also larger than 10- 6, indicating high potential carcinogenic risk. During the same season, the ILCR of adults was greater than that of other age groups and that of females was a little higher than of males. With respect to the season, the ranking of ILCR in decreasing order was as follows: winter, spring, autumn, and summer.

Polymorphic mimicry, microhabitat use, and sex-specific behaviour.

PubMed

Joron, M

2005-05-01

In order to assess the adaptive importance of microhabitat segregation for the maintenance of mimetic diversity, I explore how flight height varies between the sympatric forms of the polymorphic butterfly Heliconius numata and their respective models in the genus Melinaea. There is no evidence for vertical stratification of mimicry rings in these tiger-patterned butterflies, but males of H. numata tend to fly significantly higher than females and the Melinaea models. This difference in microhabitat preference likely results from females searching for host plants whereas males are patrolling for mates. I then present an extension of Muller's mimicry model for the case of partial behavioural or spatial segregation of sexes. The analysis suggests that sex-specific behaviours can make mimicry more beneficial, simply by reducing the effective population size participating in mimicry. The interaction between mimicry and sex-specific behaviours may therefore facilitate the evolution of polymorphism via enhanced, fine-scale local adaptation.

A Handheld Open-Field Infant Keratometer (An American Ophthalmological Society Thesis)

PubMed Central

Miller, Joseph M.

2010-01-01

Purpose: To design and evaluate a new infant keratometer that incorporates an unobstructed view of the infant with both eyes (open-field design). Methods: The design of the open-field infant keratometer is presented, and details of its construction are given. The design incorporates a single-ring keratoscope for measurement of corneal astigmatism over a 4-mm region of the cornea and includes a rectangular grid target concentric within the ring to allow for the study of higher-order aberrations of the eye. In order to calibrate the lens and imaging system, a novel telecentric test object was constructed and used. The system was bench calibrated against steel ball bearings of known dimensions and evaluated for accuracy while being used in handheld mode in a group of 16 adult cooperative subjects. It was then evaluated for testability in a group of 10 infants and toddlers. Results: Results indicate that while the device achieved the goal of creating an open-field instrument containing a single-ring keratoscope with a concentric grid array for the study of higher-order aberrations, additional work is required to establish better control of the vertex distance. Conclusion: The handheld open-field infant keratometer demonstrates testability suitable for the study of infant corneal astigmatism. Use of collimated light sources in future iterations of the design must be incorporated in order to achieve the accuracy required for clinical investigation. PMID:21212850

A handheld open-field infant keratometer (an american ophthalmological society thesis).

PubMed

Miller, Joseph M

2010-12-01

To design and evaluate a new infant keratometer that incorporates an unobstructed view of the infant with both eyes (open-field design). The design of the open-field infant keratometer is presented, and details of its construction are given. The design incorporates a single-ring keratoscope for measurement of corneal astigmatism over a 4-mm region of the cornea and includes a rectangular grid target concentric within the ring to allow for the study of higher-order aberrations of the eye. In order to calibrate the lens and imaging system, a novel telecentric test object was constructed and used. The system was bench calibrated against steel ball bearings of known dimensions and evaluated for accuracy while being used in handheld mode in a group of 16 adult cooperative subjects. It was then evaluated for testability in a group of 10 infants and toddlers. Results indicate that while the device achieved the goal of creating an open-field instrument containing a single-ring keratoscope with a concentric grid array for the study of higher-order aberrations, additional work is required to establish better control of the vertex distance. The handheld open-field infant keratometer demonstrates testability suitable for the study of infant corneal astigmatism. Use of collimated light sources in future iterations of the design must be incorporated in order to achieve the accuracy required for clinical investigation.

Higher-Order Systematic Effects in the Muon Beam-Spin Dynamics for Muon g-2

NASA Astrophysics Data System (ADS)

Crnkovic, Jason; Brown, Hugh; Krouppa, Brandon; Metodiev, Eric; Morse, William; Semertzidis, Yannis; Tishchenko, Vladimir

2016-03-01

The BNL Muon g-2 Experiment (E821) produced a precision measurement of the muon anomalous magnetic moment, where as the Fermilab Muon g-2 Experiment (E989) is an upgraded version of E821 that has a goal of producing a measurement with approximately 4 times more precision. Improving the precision requires a more detailed understanding of the experimental systematic effects, and so three higher-order systematic effects in the muon beam-spin dynamics have recently been found and estimated for E821. The beamline systematic effect originates from muon production in beamline spectrometers, as well as from muons traversing beamline bending magnets. The kicker systematic effect comes from a combination of the variation in time spent inside the muon storage ring across a muon bunch and the temporal structure of the storage ring kicker waveform. Finally, the detector systematic effect arises from a combination of the energy dependent muon equilibrium orbit in the storage ring, muon decay electron drift time, and decay electron detector acceptance effects. Brookhaven Natl Lab.

Mechanism of TRIM25 Catalytic Activation in the Antiviral RIG-I Pathway

DOE PAGES

Sanchez, Jacint G.; Chiang, Jessica J.; Sparrer, Konstantin M. J.; ...

2016-07-14

Antiviral response pathways induce interferon by higher-order assembly of signaling complexes called signalosomes. Assembly of the RIG-I signalosome is regulated by K63-linked polyubiquitin chains, which are synthesized by the E3 ubiquitin ligase, TRIM25. We have previously shown that the TRIM25 coiled-coil domain is a stable, antiparallel dimer that positions two catalytic RING domains on opposite ends of an elongated rod. We now show that the RING domain is a separate self-association motif that engages ubiquitin-conjugated E2 enzymes as a dimer. RING dimerization is required for catalysis, TRIM25-mediated RIG-I ubiquitination, interferon induction, and antiviral activity. We also provide evidence that RINGmore » dimerization and E3 ligase activity are promoted by binding of the TRIM25 SPRY domain to the RIG-I effector domain. These results indicate that TRIM25 actively participates in higher-order assembly of the RIG-I signalosome and helps to fine-tune the efficiency of the RIG-I-mediated antiviral response.« less

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

Eriksson, Mikael

Not very long ago, the 3{sup rd} generation storage ring technology was judged as mature. Most of the 3{sup rd} generation storage rings used the Double-Bend Achromat (DBA) or Triple-Bend Achromat (TBA) concepts. It was however a well-known fact that increasing the number of magnet cells in the rings is a powerful way of decreasing the electron beam emittance and thus the source brilliance, but at the penalty of increasing the size and cost of the rings. Preserving the Dynamic Aperture (DA) in the rings became also an issue when increasing the number of magnet cells. The Multi-Bend Achromat (MBA)more » concept, including a miniaturization of the ring elements, has now drastically changed the picture. The MBA rings, now in construction or being planned, offer orders of magnitudes higher brilliance than rings of conventional designs. Several light sources around the world are now implementing or planning to implement this MBA concept. This article touches on the science drivers for higher brilliance. We will then describe the MBA concept with its advantages as well as its challenges. A short survey of the MBA activity around the world will also be presented. The author apologies for focusing on the MAX IV project regarding technical solutions. This is motivated by that MAX IV is the facility he knows best and it might be regarded as a fore-runner for the MBA concept.« less

Synthesis of Benzannulated Medium-ring Lactams via a Tandem Oxidative Dearomatization-Ring Expansion Reaction.

PubMed

Guney, Tezcan; Wenderski, Todd A; Boudreau, Matthew W; Tan, Derek S

2018-06-23

Medium-ring natural products exhibit diverse biological activities but such scaffolds are underrepresented in probe and drug discovery efforts due to the limitations of classical macrocyclization reactions. We report herein a tandem oxidative dearomatization-ring-expanding rearoma¬tization (ODRE) reaction that generates benzannulated medium-ring lactams directly from simple bicyclic substrates. The reaction accommodates diverse aryl substrates (haloarenes, aryl ethers, aryl amides, heterocycles) and strategic incorporation of a bridgehead alcohol generates a versatile ketone moiety in the products amenable to downstream modifications. Cheminformatic analysis indicates that these medium rings access regions of chemical space that overlap with related natural products and are distinct from synthetic drugs, setting the stage for their use in discovery screening against novel biological targets. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Classroom Thoughtfulness and Students' Higher Order Thinking: Common Indicators and Diverse Social Studies Courses. Final Deliverable.

ERIC Educational Resources Information Center

Newmann, Fred M.

This project developed a conceptualization of higher order thinking, dimensions of classroom thoughtfulness, and an assessment exercise applicable to diverse topics taught in more than 70 classes in 11 high schools. Generic qualities of classroom thoughtfulness were not generally associated with the persuasiveness of student writing on a…

Pursuing through Culturally Relevant Pedagogy

ERIC Educational Resources Information Center

Clark, Amy Aparicio

2013-01-01

The demographic profile of Conard High School in West Hartford, CT, reflects the national trends in "first-ring suburbs." Neither fully urban nor fully suburban, first-ring suburbs went from being generally less diverse than the nation in 1980 to more diverse by 2000 (Puentes, 2006). Conard students speak 53 different languages at home,…

Application of combinatorial biocatalysis for a unique ring expansion of dihydroxymethylzearalenone

USDA-ARS?s Scientific Manuscript database

Combinatorial biocatalysis was applied to generate a diverse set of dihydroxymethylzearalenone derivatives with modified ring structure. In one chemoenzymatic reaction sequence, dihydroxymethylzearalenone was first subjected to a unique enzyme-catalyzed oxidative ring opening reaction that creates ...

Variation in GMC Association Properties across the Bars, Spiral Arms, Inter-arms, and Circumnuclear Region of M100 (NGC 4321) Extracted from ALMA Observations

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

Pan, Hsi-An; Kuno, Nario, E-mail: hapan@asiaa.sinica.edu.tw

2017-04-20

We study the physical properties of giant molecular cloud associations (GMAs) in M100 (NGC 4321) using the ALMA Science Verification feathered (12 m+ACA) data in {sup 12}CO (1–0). To examine the environmental dependence of their properties, GMAs are classified based on their locations in various environments as circumnuclear ring (CNR), bar, spiral, and inter-arm GMAs. The CNR GMAs are massive and compact, while the inter-arm GMAs are diffuse, with low surface density. GMA mass and size are strongly correlated, as suggested by Larson. However, the diverse power-law index of the relation implies that the GMA properties are not uniform amongmore » the environments. The CNR and bar GMAs show higher velocity dispersion than those in other environments. We find little evidence for a correlation between GMA velocity dispersion and size, which indicates that the GMAs are in diverse dynamical states. Indeed, the virial parameter of the GMAs spans nearly two orders of magnitude. Only the spiral GMAs are generally self-gravitating. Star formation activity decreases in order over the CNR, spiral, bar, and inter-arm GMAs. The diverse GMA and star formation properties in different environments lead to variations in the Kennicutt–Schmidt relation. A combination of multiple mechanisms or gas phase change is necessary to explain the observed slopes. Comparisons of GMA properties acquired with the use of the 12 m array observations with those from the feathered data are also presented. The results show that the missing flux and extended emission cannot be neglected for the study of environmental dependence.« less

Variation in GMC Association Properties across the Bars, Spiral Arms, Inter-arms, and Circumnuclear Region of M100 (NGC 4321) Extracted from ALMA Observations

NASA Astrophysics Data System (ADS)

Pan, Hsi-An; Kuno, Nario

2017-04-01

We study the physical properties of giant molecular cloud associations (GMAs) in M100 (NGC 4321) using the ALMA Science Verification feathered (12 m+ACA) data in 12CO (1-0). To examine the environmental dependence of their properties, GMAs are classified based on their locations in various environments as circumnuclear ring (CNR), bar, spiral, and inter-arm GMAs. The CNR GMAs are massive and compact, while the inter-arm GMAs are diffuse, with low surface density. GMA mass and size are strongly correlated, as suggested by Larson. However, the diverse power-law index of the relation implies that the GMA properties are not uniform among the environments. The CNR and bar GMAs show higher velocity dispersion than those in other environments. We find little evidence for a correlation between GMA velocity dispersion and size, which indicates that the GMAs are in diverse dynamical states. Indeed, the virial parameter of the GMAs spans nearly two orders of magnitude. Only the spiral GMAs are generally self-gravitating. Star formation activity decreases in order over the CNR, spiral, bar, and inter-arm GMAs. The diverse GMA and star formation properties in different environments lead to variations in the Kennicutt-Schmidt relation. A combination of multiple mechanisms or gas phase change is necessary to explain the observed slopes. Comparisons of GMA properties acquired with the use of the 12 m array observations with those from the feathered data are also presented. The results show that the missing flux and extended emission cannot be neglected for the study of environmental dependence.

Diverse growth trends and climate responses across Eurasia’s boreal forest

NASA Astrophysics Data System (ADS)

Hellmann, Lena; Agafonov, Leonid; Charpentier Ljungqvist, Fredrik; Churakova (Sidorova, Olga; Düthorn, Elisabeth; Esper, Jan; Hülsmann, Lisa; Kirdyanov, Alexander V.; Moiseev, Pavel; Myglan, Vladimir S.; Nikolaev, Anatoly N.; Reinig, Frederick; Schweingruber, Fritz H.; Solomina, Olga; Tegel, Willy; Büntgen, Ulf

2016-07-01

The area covered by boreal forests accounts for ˜16% of the global and 22% of the Northern Hemisphere landmass. Changes in the productivity and functioning of this circumpolar biome not only have strong effects on species composition and diversity at regional to larger scales, but also on the Earth’s carbon cycle. Although temporal inconsistency in the response of tree growth to temperature has been reported from some locations at the higher northern latitudes, a systematic dendroecological network assessment is still missing for most of the boreal zone. Here, we analyze the geographical patterns of changes in summer temperature and precipitation across northern Eurasia >60 °N since 1951 AD, as well as the growth trends and climate responses of 445 Pinus, Larix and Picea ring width chronologies in the same area and period. In contrast to widespread summer warming, fluctuations in precipitation and tree growth are spatially more diverse and overall less distinct. Although the influence of summer temperature on ring formation is increasing with latitude and distinct moisture effects are restricted to a few southern locations, growth sensitivity to June-July temperature variability is only significant at 16.6% of all sites (p ≤ 0.01). By revealing complex climate constraints on the productivity of Eurasia’s northern forests, our results question the a priori suitability of boreal tree-ring width chronologies for reconstructing summer temperatures. This study further emphasizes regional climate differences and their role on the dynamics of boreal ecosystems, and also underlines the importance of free data access to facilitate the compilation and evaluation of massively replicated and updated dendroecological networks.

Comparison of African and North American velvet ant mimicry complexes: Another example of Africa as the 'odd man out'.

PubMed

Wilson, Joseph S; Pan, Aaron D; Limb, Erica S; Williams, Kevin A

2018-01-01

Africa has the most tropical and subtropical land of any continent, yet has relatively low species richness in several taxa. This depauperate nature of the African tropical fauna and flora has led some to call Africa the "odd man out." One exception to this pattern is velvet ants (Hymenoptera: Mutillidae), wingless wasps that are known for Müllerian mimicry. While North American velvet ants form one of the world's largest mimicry complexes, mimicry in African species has not been investigated. Here we ask do African velvet ant Müllerian mimicry rings exist, and how do they compare to the North American complex. We then explore what factors might contribute to the differences in mimetic diversity between continents. To investigate this we compared the color patterns of 304 African velvet ant taxa using nonmetric multidimensional scaling (NMDS). We then investigated distributions of each distinct mimicry ring. Finally, we compared lizard diversity and ecoregion diversity on the two continents. We found that African female velvet ants form four Müllerian rings, which is half the number of North American rings. This lower mimetic diversity could be related to the relatively lower diversity of insectivorous lizard species or to the lower number of distinct ecoregions in Africa compared to North America.

Saturn's Internal Structure: A View through its Natural Seismograph

NASA Astrophysics Data System (ADS)

Mankovich, Christopher; Marley, Mark S.; Fortney, Jonathan J.; Movshovitz, Naor

2017-10-01

Saturn's nonradial oscillations perturb the orbits of ring particles. The C ring is fortuitous in that it spans several resonances with Saturn's fundamental acoustic (f-) modes, and its moderate optical depth allows the characterization of wave features using stellar occultations. The growing set of C-ring waves with precise pattern frequencies and azimuthal order m measured from Cassini stellar occultations (Hedman & Nicholson 2013, 2014; French et al. 2016) provides new constraints on Saturn's internal structure, with the potential to resolve long-standing questions about the planet's distribution of helium and heavier elements, its means of internal energy transport, and its rotation state.We construct Saturn interior models and calculate mode eigenfrequencies, mapping the planet mode frequencies to resonant locations in the rings to compare with the locations of observed spiral density and vertical bending waves in the C ring. While spiral density waves at low azimuthal order (m=2-3) appear strongly affected by resonant coupling between f-modes and deep g-modes (Fuller 2014), the locations of waves with higher azimuthal order can be fit reasonably well with a spectrum of pure f-modes for Saturn models with adiabatic envelopes and realistic equations of state. In particular, four observed bending waves (Nicholson et al., DPS 2016) align with outer vertical resonances for non-sectoral (m≠l) Saturn f-modes of relatively high angular degree, and we present preliminary identifications of these. We assess the range of resonance locations in the C and D rings allowed for the spectrum of f-modes given gravity field constraints and discuss what role a realistic helium distribution in the planet might play.

RF System Requirements for a Medium-Energy Electron-Ion Collider (MEIC) at JLab

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

Rimmer, Robert A; Hannon, Fay E; Guo, Jiquan

2015-09-01

JLab is studying options for a medium energy electron-ion collider that could fit on the JLab site and use CEBAF as a full-energy electron injector. A new ion source, linac and booster would be required, together with collider storage rings for the ions and electrons. In order to achieve the maximum luminosity these will be high-current storage rings with many bunches. We present the high-level RF system requirements for the storage rings, ion booster ring and high-energy ion beam cooling system, and describe the technology options under consideration to meet them. We also present options for staging that might reducemore » the initial capital cost while providing a smooth upgrade path to a higher final energy. The technologies under consideration may also be useful for other proposed storage ring colliders or ultimate light sources.« less

Repetition rate multiplication of frequency comb using all-pass fiber resonator

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

Yang, Lijun; Yang, Honglei; Zhang, Hongyuan

2016-09-15

We propose a stable method for repetition rate multiplication of a 250-MHz Er-fiber frequency comb by a phase-locked all-pass fiber ring resonator, whose phase-locking configuration is simple. The optical path length of the fiber ring resonator is automatically controlled to be accurately an odd multiple of half of the original cavity length using an electronical phase-locking unit with an optical delay line. As for shorter cavity length of the comb, high-order odd multiple is preferable. Because the power loss depends only on the net-attenuation of the fiber ring resonator, the energetic efficiency of the proposed method is high. The inputmore » and output optical spectrums show that the spectral width of the frequency comb is clearly preserved. Besides, experimental results show less pulse intensity fluctuation and 35 dB suppression ratio of side-modes while providing a good long-term and short-term frequency stability. Higher-order repetition rate multiplication to several GHz can be obtained by using several fiber ring resonators in cascade configuration.« less

Real-time track-less Cherenkov ring fitting trigger system based on Graphics Processing Units

NASA Astrophysics Data System (ADS)

Ammendola, R.; Biagioni, A.; Chiozzi, S.; Cretaro, P.; Cotta Ramusino, A.; Di Lorenzo, S.; Fantechi, R.; Fiorini, M.; Frezza, O.; Gianoli, A.; Lamanna, G.; Lo Cicero, F.; Lonardo, A.; Martinelli, M.; Neri, I.; Paolucci, P. S.; Pastorelli, E.; Piandani, R.; Piccini, M.; Pontisso, L.; Rossetti, D.; Simula, F.; Sozzi, M.; Vicini, P.

2017-12-01

The parallel computing power of commercial Graphics Processing Units (GPUs) is exploited to perform real-time ring fitting at the lowest trigger level using information coming from the Ring Imaging Cherenkov (RICH) detector of the NA62 experiment at CERN. To this purpose, direct GPU communication with a custom FPGA-based board has been used to reduce the data transmission latency. The GPU-based trigger system is currently integrated in the experimental setup of the RICH detector of the NA62 experiment, in order to reconstruct ring-shaped hit patterns. The ring-fitting algorithm running on GPU is fed with raw RICH data only, with no information coming from other detectors, and is able to provide more complex trigger primitives with respect to the simple photodetector hit multiplicity, resulting in a higher selection efficiency. The performance of the system for multi-ring Cherenkov online reconstruction obtained during the NA62 physics run is presented.

Repetitive Protein Unfolding by the trans Ring of the GroEL-GroES Chaperonin Complex Stimulates Folding*

PubMed Central

Lin, Zong; Puchalla, Jason; Shoup, Daniel; Rye, Hays S.

2013-01-01

A key constraint on the growth of most organisms is the slow and inefficient folding of many essential proteins. To deal with this problem, several diverse families of protein folding machines, known collectively as molecular chaperones, developed early in evolutionary history. The functional role and operational steps of these remarkably complex nanomachines remain subjects of active debate. Here we present evidence that, for the GroEL-GroES chaperonin system, the non-native substrate protein enters the folding cycle on the trans ring of the double-ring GroEL-ATP-GroES complex rather than the ADP-bound complex. The properties of this ATP complex are designed to ensure that non-native substrate protein binds first, followed by ATP and finally GroES. This binding order ensures efficient occupancy of the open GroEL ring and allows for disruption of misfolded structures through two phases of multiaxis unfolding. In this model, repeated cycles of partial unfolding, followed by confinement within the GroEL-GroES chamber, provide the most effective overall mechanism for facilitating the folding of the most stringently dependent GroEL substrate proteins. PMID:24022487

Cycloalkyl-AminoMethylRhodamines: pH Dependent Photophysical Properties Tuned by Cycloalkane Ring Size

PubMed Central

Liu, Chuangjun; Best, Quinn A.; Suarez, Brian; Pertile, Jack; McCarroll, Matthew E.; Scott, Colleen N.

2015-01-01

A series of fluorescent pH probes based on the spiro-cyclic rhodamine core, aminomethylrhodamines (AMR), was synthesized and the effect of cycloalkane ring size on the acid/base properties of the AMR system was explored. The study involved a series of rhodamine 6G (cAMR6G) and rhodamine B (cAMR) pH probes with cycloalkane ring sizes from C-3 to C-6 on the spiro-cyclic amino group. It is known that the pKa value of cycloalkylamines can be tuned by the different ring sizes in accordance with the Baeyer ring strain theory. Smaller ring amines have lower pKa value, i.e. they're less basic, such that the relative order in cycloalkylamine basicity is: cyclohexyl>cyclopentyl>cyclobutyl>cyclopropyl. Herein, it was found that the pKa values of the cAMR and cAMR6G systems can also be predicted by Baeyer ring strain theory. The pKa values for the cAMR6G series were shown to be higher than the cAMR series by a value of approximately 1. PMID:25686771

Comparison of African and North American velvet ant mimicry complexes: Another example of Africa as the ‘odd man out’

PubMed Central

Limb, Erica S.; Williams, Kevin A.

2018-01-01

Africa has the most tropical and subtropical land of any continent, yet has relatively low species richness in several taxa. This depauperate nature of the African tropical fauna and flora has led some to call Africa the “odd man out.” One exception to this pattern is velvet ants (Hymenoptera: Mutillidae), wingless wasps that are known for Müllerian mimicry. While North American velvet ants form one of the world’s largest mimicry complexes, mimicry in African species has not been investigated. Here we ask do African velvet ant Müllerian mimicry rings exist, and how do they compare to the North American complex. We then explore what factors might contribute to the differences in mimetic diversity between continents. To investigate this we compared the color patterns of 304 African velvet ant taxa using nonmetric multidimensional scaling (NMDS). We then investigated distributions of each distinct mimicry ring. Finally, we compared lizard diversity and ecoregion diversity on the two continents. We found that African female velvet ants form four Müllerian rings, which is half the number of North American rings. This lower mimetic diversity could be related to the relatively lower diversity of insectivorous lizard species or to the lower number of distinct ecoregions in Africa compared to North America. PMID:29298332

What Style of Leadership Is Best Suited to Direct Organizational Change to Fuel Institutional Diversity in Higher Education?

ERIC Educational Resources Information Center

Adserias, Ryan P.; Charleston, LaVar J.; Jackson, Jerlando F. L.

2017-01-01

Implementing diversity agendas within decentralized, loosely coupled, and change-resistant institutions such as colleges and universities is a global challenge. A shift in the organizational climate and culture is imperative to produce the change needed in order for a diversity agenda to thrive. Higher education scholars have consistently…

Institutional Diversity in Ontario's University Sector: A Policy Debate Analysis

ERIC Educational Resources Information Center

Piché, Pierre G.; Jones, Glen A.

2016-01-01

In order to meet the demands in a cost-effective manner of an emerging knowledge society that is global in scope, structural higher education policy changes have been introduced in many countries with a focus on systemic and programmatic diversity. There has been an ongoing debate about institutional diversity in Ontario higher education,…

A View into Saturn through its Natural Seismograph

NASA Astrophysics Data System (ADS)

Mankovich, Christopher

2018-04-01

Saturn's nonradial oscillations perturb the orbits of ring particles. The C ring is fortuitous in that it spans several resonances with Saturn's fundamental acoustic (f-) modes, and its moderate optical depth allows the characterization of wave features using stellar occultations. The growing set of C-ring waves with precise pattern frequencies and azimuthal order m measured from Cassini stellar occultations (Hedman & Nicholson 2013, 2014; French et al. 2016) provides new constraints on Saturn's internal structure, with the potential to aid in resolving long-standing questions about the planet's distribution of helium and heavier elements, its means of internal energy transport, and its rotation state.We construct Saturn interior models and calculate mode eigenfrequencies, mapping the planet mode frequencies to resonant locations in the rings to compare with the locations of observed spiral density and vertical bending waves in the C ring. While spiral density waves at low azimuthal order (m=2-3) appear strongly affected by resonant coupling between f-modes and deep g-modes (Fuller 2014), the locations of waves with higher azimuthal order can be fit with a spectrum of pure f-modes for Saturn models with adiabatic envelopes and realistic equations of state. Notably, several newly observed density waves and bending waves (Nicholson et al., in preparation) align with outer Lindblad and outer vertical resonances for non-sectoral (m!=l) Saturn f-modes of relatively high angular degree, and we present normal mode identifications for these waves. We assess the range of resonance locations in the C and D rings allowed for the spectrum of f-modes given gravity field constraints, point to other resonance locations that should experience strong forcing, and use the full set of observed waves to estimate Saturn's bulk rotation rate.

Evidence that displacement activities facilitate behavioural transitions in ring-tailed lemurs.

PubMed

Buckley, Victoria; Semple, Stuart

2012-07-01

Displacement activities are behavioural patterns defined by their apparent irrelevance to an animal's ongoing actions. Despite being identified in diverse taxa, their function remains poorly understood. One hypothesis posits that displacement activities facilitate transitions between different behaviours by mediating changes in animals' motivational state. Under this hypothesis, it is predicted that displacement activities will occur more frequently around changes in behaviour than at other times, and also that rates of displacement activities will be higher before than after such behavioural transitions. We tested these two predictions in wild ring-tailed lemurs (Lemur catta). During focal observations, animals' behavioural state was continuously recorded, as were all occurrences of self-scratching, a common displacement activity in this species. Self-scratching rates were found to be significantly elevated both before and after behavioural transitions. Furthermore, self-scratching rates were significantly higher before behavioural transitions occurred than after. These results, therefore, provide support for the hypothesis that displacement activities facilitate behavioural transitions in L. catta. Copyright © 2012 Elsevier B.V. All rights reserved.

Ferrite HOM Absorber for the RHIC ERL

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

Hahn,H.; Choi, E.M.; Hammons, L.

A superconducting Energy Recovery Linac is under construction at Brookhaven National Laboratory to serve as test bed for RHIC upgrades. The damping of higher-order modes in the superconducting five-cell cavity for the Energy-Recovery linac at RHIC is performed exclusively by two ferrite absorbers. The ferrite properties have been measured in ferrite-loaded pill box cavities resulting in the permeability values given by a first-order Debye model for the tiled absorber structure and an equivalent permeability value for computer simulations with solid ring dampers. Measured and simulated results for the higher-order modes in the prototype copper cavity are discussed. First room-temperature measurementsmore » of the finished niobium cavity are presented which confirm the effective damping of higher-order modes in the ERL. by the ferrite absorbers.« less

Ring-rearrangement metathesis of nitroso Diels-Alder cycloadducts.

PubMed

Vincent, Guillaume; Kouklovsky, Cyrille

2011-03-01

Strained nitroso Diels-Alder bicyclo[2.2.1] or [2.2.2] adducts functionalized with alkene side chains of diverse length undergo a ring-rearrangement metathesis process with external alkenes and Grubbs II or Hoveyda-Grubbs II ruthenium catalysts, under microwave irradiation or classical heating, to deliver cis-fused bicycles of various ring sizes, which contain a N-O bond. These scaffolds are of synthetic relevance for the generation of molecular diversity and to the total synthesis of alkaloids. The observation of unexpected reactions, such as epimerization or one-carbon homologation of the alkene side chain, is also reported. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thermal collapse and hierarchy of polymorphs in a faujasite-type zeolite and its analogous melt-quenched glass

NASA Astrophysics Data System (ADS)

Palenta, Theresia; Fuhrmann, Sindy; Greaves, G. Neville; Schwieger, Wilhelm; Wondraczek, Lothar

2015-02-01

We examine the route of structural collapse and re-crystallization of faujasite-type (Na,K)-LSX zeolite. As the first step, a rather stable amorphous high density phase HDAcollapse is generated through an order-disorder transition from the original zeolite via a low density phase LDAcollapse, at around 790 °C. We find that the overall amorphization is driven by an increase in the bond angle distribution within T-O-T and a change in ring statistics to 6-membered TO4 (T = Si4+, Al3+) rings at the expense of 4-membered rings. The HDAamorph transforms into crystalline nepheline, though, through an intermediate metastable carnegieite phase. In comparison, the melt-derived glass of similar composition, HDAMQ, crystallizes directly into the nepheline phase without the occurrence of intermediate carnegieite. This is attributed to the higher structural order of the faujasite-derived HDAcollapse which prefers the re-crystallization into the highly symmetric carnegieite phase before transformation into nepheline with lower symmetry.

Comparison of detection limit in fiber-based conventional, amplified, and gain-clamped cavity ring-down techniques

NASA Astrophysics Data System (ADS)

Sharma, K.; Abdul Khudus, M. I. M.; Alam, S. U.; Bhattacharya, S.; Venkitesh, D.; Brambilla, G.

2018-01-01

Relative performance and detection limit of conventional, amplified, and gain-clamped cavity ring-down techniques (CRDT) in all-fiber configurations are compared experimentally for the first time. Refractive index measurement using evanescent field in tapered fibers is used as a benchmark for the comparison. The systematic optimization of a nested-loop configuration in gain-clamped CRDT is also discussed, which is crucial for achieving a constant gain in a CRDT experiment. It is found that even though conventional CRDT has the lowest standard error in ring-down time (Δτ), the value of ring-down time (τ) is very small, thus leading to poor detection limit. Amplified CRDT provides an improvement in τ, albeit with two orders of magnitude higher Δτ due to amplifier noise. The nested-loop configuration in gain-clamped CRDT helps in reducing Δτ by an order of magnitude as compared to amplified CRDT whilst retaining the improvement in τ. A detection limit of 1 . 03 × 10-4 RIU at refractive index of 1.322 with a 3 mm long and 4.5 μm diameter tapered fiber is demonstrated with the gain-clamped CRDT.

Centrifugal distortion and the ring puckering vibration in the microwave spectrum of 2,3-dihydrofuran

NASA Astrophysics Data System (ADS)

Cervellati, R.; Degli Esposti, A.; Lister, D. G.; Lopez, J. C.; Alonso, J. L.

1986-10-01

The microwave spectrum of 2,3-dihydrofuran has been reinvestigated and measurements for the ground and first five excited states of the ring puckering vibration have been extended to higher frequencies and rotational quantum numbers in order to study the vibrational dependence of the rotational and centrifugal distortion constants. The ring puckering potential function derived by Green from the far infrared spectrum does not reproduce the vibrational dependence of the rotational constants well. A slightly different potential function is derived which gives a reasonable fit both to the far infrared spectrum and the rotational constants. This changes the barrier to ring inversion from 1.00 kJ mol -1 to 1.12 kJ mol -1. The vibrational dependence of the centrifugal distortion constants is accounted for satisfactorily by the theory developed by Creswell and Mills. An attempt to reproduce the vibrational dependence of the rotational and centrifugal distortion constants using the ring puckering potential function and a simple model for this vibration has very limited success.

Evidence for Break-Up of Clumps in Dynamically Stirred Regions of Saturn's Rings

NASA Astrophysics Data System (ADS)

Colwell, J. E.; Sega, D. N.; Jerousek, R. G.; Cooney, J. H.; Esposito, L. W.

2017-12-01

Stellar occultations of Saturn's rings observed by the Cassini Ultraviolet Imaging Spectrograph (UVIS) High Speed Photometer (HSP) record stellar brightness seen through the rings as photon counts that are described by Poisson counting statistics in the absence of intervening ring material. The variance in the data increases above counting statistics due to the discrete sizes of the ring particles, with larger particles leading to a larger variance at a given optical depth. We take advantage of the high spatial resolution and multiple viewing geometries of the UVIS occultations to study variations in particle size near and within strongly perturbed regions of Saturn's A ring, in particular the strong first order Lindblad resonances with Janus and the Mimas 5:3 Lindblad resonance and inner vertical resonance. The variance shows changes in the area-weighted particle size between peaks and troughs in the density waves as well as an overall decrease in particle size in the broad "halo" regions that bracket the strong Janus Lindblad resonances in the A ring. In addition we see a decrease in particle size at the location of the Mimas 5:3 bending wave wavetrain itself, and an increase in optical depth at the location of the wave when viewed from high elevation angles out of the ring plane. Taken together, these observations suggest that clumps of particles, perhaps the ubiquitous A ring self-gravity wakes, are disaggregated in the bending wave, even though standard bending wave theory does not predict enhanced collision velocities. We also examine the skewness, a higher order moment of the occultation data, that is diagnostic of asymmetries in the particle size distribution. We use Monte Carlo simulations of occultations to match the first three moments of the data (the signal mean, or equivalently the optical depth, the variance, and the skewness) to illustrate differences in ring particle size in these perturbed regions.

Photoswitchable Fluorescent Diarylethene Derivatives with Thiophene 1,1-Dioxide Groups: Effect of Alkyl Substituents at the Reactive Carbons

PubMed Central

Sumi, Takaki; Irie, Masahiro

2017-01-01

Photoswitching and fluorescent properties of sulfone derivatives of 1,2-bis(2-alkyl-4-methyl-5-phenyl-3-thienyl)perfluorocyclopentene, 1–5, having methyl, ethyl, n-propyl, i-propyl, and i-butyl substituents at the reactive carbons (2- and 2′-positions) of the thiophene 1,1-dioxide rings were studied. Diarylethenes 1–5 underwent isomerization reactions between open-ring and closed-ring forms upon alternate irradiation with ultraviolet (UV) and visible light and showed fluorescence in the closed-ring forms. The alkyl substitution at the reactive carbons affects the fluorescent property of the closed-ring isomers. The closed-ring isomers 2b–5b with ethyl, n-propyl, i-propyl, and i-butyl substituents show higher fluorescence quantum yields than 1b with methyl substituents. In polar solvents, the fluorescence quantum yield of 1b markedly decreases, while 2b–5b maintain the relatively high fluorescence quantum yields. Although the cycloreversion quantum yields of the derivatives with methyl, ethyl, n-propyl, and i-propyl substituents are quite low and in the order of 10−5, introduction of i-butyl substituents was found to increase the yield up to the order of 10−3. These results indicate that appropriate alkyl substitution at the reactive carbons is indispensable for properly controlling the photoswitching and fluorescent properties of the photoswitchable fluorescent diarylethenes, which are potentially applicable to super-resolution fluorescence microscopies. PMID:28869489

Designing high efficiency organic photovoltaics by controlling the ordering at the donor-acceptor interface

NASA Astrophysics Data System (ADS)

Mohite, Aditya; Nie, Wanyi; Gupta, Gautam; Crone, Brian; Kuo, Chenyu; Tsai, Hsinhan; Smith, Darryl; Ruden, Paul; Liu, Feilong; Wang, Hsing-Lin; Tretiak, Sergei

2014-03-01

The overall power conversion efficiency in an organic solar cell depends on the balance between the rates of exciton dissociation, recombination and separation at the donor acceptor interface. Inability to design, control and engineer these interfaces remains a key bottleneck in their widespread use for the next generation organic electronic devices. Here, we show that we can control the ordering at the P3HT/C60 interface in bilayer device geometry by inserting a monolayer of oligothiophenes, which leads to a complete suppression in the exciplex (or charge transfer state) recombination. We observe that the photocurrent increases by 500%, which in turn results in an increase in the overall power conversion efficiency by an order of magnitude. Moreover, we find that the oligothiophene with an odd number of rings (ter and penta oligothiophene) exhibit a much higher increase in the photocurrent in comparison to the oligothiophene with an even number of rings (tetra oligothiphene). STM measurements reveal that the oligothiophene with odd and even number of rings differ in their ordering respectively, that has a big effect on the overall device performance. We also find that this ordering is highly dependent on the side functional groups in the oligothiophenes. The mechanism of photocurrent generation will be discussed and a simple transport model will be used to explain the change in the charge transfer and recombination rates and predict current-voltage curves.

High Luminosity 100 TeV Proton-Antiproton Collider

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

Oliveros, S. J.; Acosta, J. G.; Cremaldi, L. M.

2016-10-01

The energy scale for new physics is known to be in the multi-TeV range, signaling the potential need for a collider beyond the LHC. Amore » $$10^{34}$$ cm$$^{-2}$$ s$$^{-1}$$ luminosity 100 TeV proton-antiproton collider is explored. Prior engineering studies for 233 and 270 km circumference tunnels were done for Illinois dolomite and Texas chalk signaling manageable tunneling costs. At a $$p\\bar{p}$$ the cross section for high mass states is of order 10x higher with antiproton collisions, where antiquarks are directly present rather than relying on gluon splitting. The higher cross sections reduce the synchrotron radiation in superconducting magnets, because lower beam currents can produce the same rare event rates. In our design the increased momentum acceptance (11 $$\\pm$$ 2.6 GeV/c) in a Fermilab-like antiproton source is used with septa to collect 12x more antiprotons in 12 channels. For stochastic cooling, 12 cooling systems would be used, each with one debuncher/momentum equalizer ring and two accumulator rings. One electron cooling ring would follow. Finally antiprotons would be recycled during runs without leaving the collider ring, by joining them to new bunches with synchrotron damping.« less

Functional diversity, succession, and human-mediated disturbances in raised bog vegetation.

PubMed

Dyderski, Marcin K; Czapiewska, Natalia; Zajdler, Mateusz; Tyborski, Jarosław; Jagodziński, Andrzej M

2016-08-15

Raised and transitional bogs are one of the most threatened types of ecosystem, due to high specialisation of biota, associated with adaptations to severe environmental conditions. The aim of the study was to characterize the relationships between functional diversity (reflecting ecosystem-shaping processes) of raised bog plant communities and successional gradients (expressed as tree dimensions) and to show how impacts of former clear cuts may alter these relationships in two raised bogs in 'Bory Tucholskie' National Park (N Poland). Herbaceous layers of the plant communities were examined by floristic relevés (25m(2)) on systematically established transects. We also assessed patterns of tree ring widths. There were no relationships between vegetation functional diversity components and successional progress: only functional dispersion was negatively, but weakly, correlated with median DBH. Lack of these relationships may be connected with lack of prevalence of habitat filtering and low level of competition over all the successional phases. Former clear cuts, indicated by peaks of tree ring width, influenced the growth of trees in the bogs studied. In the bog with more intensive clear cuts we found more species with higher trophic requirements, which may indicate nutrient influx. However, we did not observe differences in vegetation patterns, functional traits or functional diversity indices between the two bogs studied. We also did not find an influence of clear cut intensity on relationships between functional diversity indices and successional progress. Thus, we found that alteration of the ecosystems studied by neighbourhood clear cuts did not affect the bogs strongly, as the vegetation was resilient to these impacts. Knowledge of vegetation resilience after clear cuts may be crucial for conservation planning in raised bog ecosystems. Copyright © 2016 Elsevier B.V. All rights reserved.

Guideline recommendations for diagnosis and clinical management of Ring14 syndrome-first report of an ad hoc task force.

PubMed

Rinaldi, Berardo; Vaisfeld, Alessandro; Amarri, Sergio; Baldo, Chiara; Gobbi, Giuseppe; Magini, Pamela; Melli, Erto; Neri, Giovanni; Novara, Francesca; Pippucci, Tommaso; Rizzi, Romana; Soresina, Annarosa; Zampini, Laura; Zuffardi, Orsetta; Crimi, Marco

2017-04-11

Ring chromosome 14 syndrome is a rare chromosomal disorder characterized by early onset refractory epilepsy, intellectual disability, autism spectrum disorder and a number of diverse health issues. The aim of this work is to provide recommendations for the diagnosis and management of persons affected by ring chromosome 14 syndrome based on evidence from literature and experience of health professionals from different medical backgrounds who have followed for several years subjects affected by ring chromosome 14 syndrome. The literature search was performed in 2016. Original papers, meta-analyses, reviews, books and guidelines were reviewed and final recommendations were reached by consensus. Conventional cytogenetics is the primary tool to identify a ring chromosome. Children with a terminal deletion of chromosome 14q ascertained by molecular karyotyping (CGH/SNP array) should be tested secondarily by conventional cytogenetics for the presence of a ring chromosome. Early diagnosis should be pursued in order to provide medical and social assistance by a multidisciplinary team. Clinical investigations, including neurophysiology for epilepsy, should be performed at the diagnosis and within the follow-up. Following the diagnosis, patients and relatives/caregivers should receive regular care for health and social issues. Epilepsy should be treated from the onset with anticonvulsive therapy. Likewise, feeding difficulties should be treated according to need. Nutritional assessment is recommended for all patients and nutritional support for malnourishment can include gastrostomy feeding in selected cases. Presence of autistic traits should be carefully evaluated. Many patients with ring chromosome 14 syndrome are nonverbal and thus maintaining their ability to communicate is always essential; every effort should be made to preserve their autonomy.

Molecular heterotopy in the expression of Brachyury orthologs in order Clypeasteroida (irregular sea urchins) and order Echinoida (regular sea urchins).

PubMed

Hibino, Taku; Harada, Yoshito; Minokawa, Takuya; Nonaka, Masaru; Amemiya, Shonan

2004-11-01

The expression patterns of Brachyury (Bra) orthologs in the development of four species of sand dollars (order: Clypeasteroida), including a direct-developing species, and of a sea urchin species (order: Echinoida) were investigated during the period from blastula to the pluteus stage, with special attention paid to the relationship between the expression pattern and the mode of gastrulation. The sand dollar species shared two expression domains of the Bra orthologs with the Echinoida species, in the vegetal ring (the first domain) and the oral ectoderm (the second domain). The following heterotopic changes in the expression of the Bra genes were found among the sand dollar species and between the sand dollars and the Echinoida species. (1) The vegetal ring expressing Bra in the sand dollars was much wider and was located at a higher position along the AV axis, compared with that in the Echinoida species. The characteristic Bra expression in the vegetal ring of the sand dollar embryos was thought to be involved in the mode of gastrulation, in which involution continues from the beginning of invagination until the end of gastrulation. (2) Two of the three indirect-developing sand dollar species that were examined exhibited a third domain, in which Bra was expressed on the oral side of the archenteron. (3) In the direct-developing sand dollar embryos, Bra was expressed with an oral-aboral asymmetry in the vegetal ring and with a left-right asymmetry in the oral ectoderm. In the Echinoida species, Bra was expressed in the vestibule at the six-armed pluteus stage.

Debye ring diffraction elucidation of 2D photonic crystal self-assembly and ordering at the air-water interface.

PubMed

Smith, N L; Coukouma, A; Dubnik, S; Asher, S A

2017-12-06

We fabricate 2D photonic crystals (2DPC) by spreading a dispersion of charged colloidal particles (diameters = 409, 570, and 915 nm) onto the surface of electrolyte solutions using a needle tip flow method. When the interparticle electrostatic interaction potential is large, particles self-assemble into highly ordered hexagonal close packed (hcp) monolayers. Ordered 2DPC efficiently forward diffract monochromatic light to produce a Debye ring on a screen parallel to the 2DPC. The diameter of the Debye ring is inversely proportional to the 2DPC particle spacing, while the Debye ring brightness and thickness depends on the 2DPC ordering. The Debye ring thickness increases as the 2DPC order decreases. The Debye ring ordering measurements of 2DPC attached to glass slides track measurements of the 2D pair correlation function order parameter calculated from SEM micrographs. The Debye ring method was used to investigate the 2DPC particle spacing, and ordering at the air-solution interface of NaCl solutions, and for 2DPC arrays attached to glass slides. Surprisingly, the 2DPC ordering does not monotonically decrease as the salt concentration increases. This is because of chloride ion adsorption onto the anionic particle surfaces. This adsorption increases the particle surface charge and compensates for the decreased Debye length of the electric double layer when the NaCl concentration is below a critical value.

Study on the effect of ellipticity and misalignment on OAM modes in a ring fiber

NASA Astrophysics Data System (ADS)

Zhang, Li-li; Zhang, Xia; Bai, Cheng-lin

2018-05-01

Based on the optical fiber mode theory and employing the expertized software COMSOL, we study the effect of ellipticity and misalignment on the effective refractive indices, walk-off and intensity distribution of the even and odd eigenmodes that form the basis of the orbital angular momentum (OAM) modes in a ring fiber. Our results show that the effective refractive index difference and the walk-off increase with the ellipticity and misalignment, thus reducing the stability of the OAM modes. We find that the misalignment has a greater impact on the OAM modes than the ellipticity, and both the misalignment and ellipticity affect the lower-order OAM modes more significantly, suggesting that the higher-order OAM modes are more stable during propagation.

Aromatic Rings Commonly Used in Medicinal Chemistry: Force Fields Comparison and Interactions With Water Toward the Design of New Chemical Entities.

PubMed

Polêto, Marcelo D; Rusu, Victor H; Grisci, Bruno I; Dorn, Marcio; Lins, Roberto D; Verli, Hugo

2018-01-01

The identification of lead compounds usually includes a step of chemical diversity generation. Its rationale may be supported by both qualitative (SAR) and quantitative (QSAR) approaches, offering models of the putative ligand-receptor interactions. In both scenarios, our understanding of which interactions functional groups can perform is mostly based on their chemical nature (such as electronegativity, volume, melting point, lipophilicity etc.) instead of their dynamics in aqueous, biological solutions (solvent accessibility, lifetime of hydrogen bonds, solvent structure etc.). As a consequence, it is challenging to predict from 2D structures which functional groups will be able to perform interactions with the target receptor, at which intensity and relative abundance in the biological environment, all of which will contribute to ligand potency and intrinsic activity. With this in mind, the aim of this work is to assess properties of aromatic rings, commonly used for drug design, in aqueous solution through molecular dynamics simulations in order to characterize their chemical features and infer their impact in complexation dynamics. For this, common aromatic and heteroaromatic rings were selected and received new atomic charge set based on the direction and module of the dipole moment from MP2/6-31G * calculations, while other topological terms were taken from GROMOS53A6 force field. Afterwards, liquid physicochemical properties were simulated for a calibration set composed by nearly 40 molecules and compared to their respective experimental data, in order to validate each topology. Based on the reliance of the employed strategy, we expanded the dataset to more than 100 aromatic rings. Properties in aqueous solution such as solvent accessible surface area, H-bonds availability, H-bonds residence time, and water structure around heteroatoms were calculated for each ring, creating a database of potential interactions, shedding light on features of drugs in biological solutions, on the structural basis for bioisosterism and on the enthalpic/entropic costs for ligand-receptor complexation dynamics.

Simulating the Smallest Ring World of Chariklo

NASA Astrophysics Data System (ADS)

Michikoshi, Shugo; Kokubo, Eiichiro

2017-03-01

A ring system consisting of two dense narrow rings has been discovered around Centaur Chariklo. The existence of these rings around a small object poses various questions about their origin, stability, and lifetime. In order to understand the nature of Chariklo’s rings, we perform global N-body simulations of the self-gravitating collisional particle rings for the first time. We find that Chariklo should be denser than the ring material in order to avoid the rapid diffusion of the rings. If Chariklo is denser than the ring material, fine spiral structures called self-gravity wakes occur in the inner ring. These wakes accelerate the viscous spreading of the ring significantly and typically occur on timescales of about 100 {years} for m-sized ring particles, which is considerably shorter than the timescales suggested in previous studies. The existence of these narrow rings implies smaller ring particles or the existence of shepherding satellites.

Illuminating the dark side of DOM: A bottom up approach to understanding the structure and composition of DOM.

NASA Astrophysics Data System (ADS)

Zito, P.; Tarr, M. A.; Spencer, R. G.; Podgorski, D. C.

2017-12-01

Dissolved organic matter (DOM) is one of the most complex natural mixtures on Earth. It is generally comprised of hydrocarbons incorporating a diverse subset of oxygen-containing functional groups along with a small amount of nitrogen, sulfur and phosphorous heteroatoms all of which make it very difficult to chromatographically separate. The only way to directly characterize and quantify these structural and compositional changes is by separating the DOM continuum into defined bins of structure and chemistry. In this study, we take an alternate bottom-up approach that utilizes petroleum to work toward identifying the molecular structures of DOM. Although petroleum is the most structurally diverse mixture in nature, it is almost exclusively comprised of hydrocarbons with only trace quantities of heteroatoms, including oxygen. Here, crude oil was chromatographically separated into bins based on the number of aromatic rings to be used as a starting carbon source. Photochemically produced DOM from these aromatic ring bins provides unique opportunities to gain insight in the compositional controls associated with transport, processing and fate of DOM in natural systems. Here, we present EEMs data from individual ring fractions that were subjected to 24 hours of sunlight to use as a model to fingerprint specific aromatic regions in the DOM fraction. Results illustrate that the 1-, 2-, 3-, 4- and 5- ring fractions exhibit a wide range of structurally dependent excitation and emission spectra. A well-known red-shift in the emission and excitation occurs as the number of rings increase. In order to understand changes in the elemental composition of the data, ultra high-resolution mass spectrometry was used to obtain molecular level information. Together, these data will provide a tool to help understand the relationship of the composition and structure of DOM released into the environment in terms of aromaticity. It is well known that aromaticity is an important indicator of the chemical characteristics of DOM and can be used to explain the role of DOM in environmental processes. Thus, identifying these compounds in terms of aromaticity after photodegradation will provide information about the fate, transport and mechanisms of the photolabile and recalcitrant compounds in the environment.

Higher-order formulas of amplitude-dependent tune shift caused by a sextupole magnetic field distribution

NASA Astrophysics Data System (ADS)

Soutome, Kouichi; Tanaka, Hitoshi

2017-06-01

Nowadays, designs for ring-based light sources use multibend lattices for achieving a very small emittance of around 100 pmrad. In this type of storage ring, the chromaticity correcting sextupoles generally have greater strengths than those used in typical third-generation light sources. Therefore, controlling lattice nonlinearity such as amplitude-dependent tune shift (ADTS) is important for enabling stable operations and smooth beam commissioning. As the strength of the sextupoles increases, their higher-order terms contribute significantly to ADTS, rendering well-known lowest-order formulas inadequate for describing tune variations at large horizontal amplitudes. In response, we have derived explicit expressions of ADTS up to the fourth order in sextupole strength based on the canonical perturbation theory, assuming that the amplitude of a vertical betatron oscillation is smaller compared with the horizontal one. The new formulas express the horizontal and vertical betatron tune variations as functions of the action variables: Jx and Jy up to O (Jx2) and O (Jy) . The derived formulas were applied to a five-bend achromat lattice designed for the SPring-8 upgrade. By comparing the calculated results with the tracking simulations, we found that (1) the formulas accurately express ADTS around a horizontal amplitude of ˜10 mm and (2) the nonlinear terms of the fourth order in sextupole strength govern the behaviors of circulating electrons at large horizontal amplitudes. In this paper, we present explicit expressions of fourth-order formulas of ADTS and provide some examples to illustrate their effectiveness.

Optical waveguides having flattened high order modes

DOEpatents

Messerly, Michael Joseph; Beach, Raymond John; Heebner, John Edward; Dawson, Jay Walter; Pax, Paul Henry

2014-08-05

A deterministic methodology is provided for designing optical fibers that support field-flattened, ring-like higher order modes. The effective and group indices of its modes can be tuned by adjusting the widths of the guide's field-flattened layers or the average index of certain groups of layers. The approach outlined here provides a path to designing fibers that simultaneously have large mode areas and large separations between the propagation constants of its modes.

Unresolving the "real age" of fine roots in forest ecosystems

NASA Astrophysics Data System (ADS)

Solly, Emily; Brunner, Ivano; Herzog, Claude; Schöning, Ingo; Schrumpf, Marion; Schweigruber, Fritz; Trumbore, Susan; Hagedorn, Frank

2016-04-01

Estimating the turnover time of tree fine roots is crucial for modelling soil organic matter dynamics, but it is one of the biggest challenges in soil ecology and one of the least understood aspects of the belowground carbon cycle. The methods used - ranging from radiocarbon to ingrowth cores and root cameras (minirhizotrons) - yield very diverse pictures of fine root dynamics in forest ecosystems with turnover rates reaching from less than one year to decades. These have huge implications on estimates of carbon allocation to root growth and maintenance and on the persistence of root carbon in soils before it is decomposed or leached. We will present a new approach, involving techniques to study plant anatomy, which unravels the "real age" of fine roots. For a range of forests with diverse water and nutrient limitations located at different latitudes, we investigated the annual growth rings in the secondary xylem of thin transversal sections of fine roots belonging to tree species which form distinct growth rings. In temperate forests we find mean root "ring ages" of 1-2 years while in sub-arctic forests living fine roots can also persist for several years. The robustness of these results were tested by counting the maximum yearly growth rings in tree seedlings of known age and by counting the maximum number of growth rings of fine roots grown in ingrowth cores which were kept in temperate forest soils for one and two years. Radiocarbon estimates of mean "carbon ages", which define the time elapsed since structural carbon was fixed from the atmosphere, instead average around a decade in root systems of temperate forests (mixture of newly produced and older living roots). This dramatic difference may not be related to methodological bias, but to a time lag between C assimilation and production of a portion of fine root tissues due to the storage of older carbon components. The time lag depends very likely on tree species and environmental conditions. We further observed that the root ring age increases with root diameter although it does not appear to be related to the branching order. Our findings suggest that both the physiological and radiocarbon ages must be modelled jointly in forest ecosystems, if we want to correctly account for the inputs of root litter

Numerical study on the lubrication performance of compression ring-cylinder liner system with spherical dimples

PubMed Central

Liu, Cheng; Zhang, Yong-Fang; Li, Sha; Müller, Norbert

2017-01-01

The effects of surface texture on the lubrication performance of a compression ring-cylinder liner system are studied in this paper. By considering the surface roughness of the compression ring and cylinder liner, a mixed lubrication model is presented to investigate the tribological behaviors of a barrel-shaped compression ring-cylinder liner system with spherical dimples on the liner. In order to determine the rupture and reformulation positions of fluid film accurately, the Jacoboson-Floberg-Olsson (JFO) cavitation boundary condition is applied to the mixed lubrication model for ensuring the mass-conservative law. On this basis, the minimum oil film thickness and average friction forces in the compression ring-cylinder liner system are investigated under the engine-like conditions by changing the dimple area density, radius, and depth. The wear load, average friction forces, and power loss of the compression ring-cylinder liner system with and without dimples are also compared for different compression ring face profiles. The results show that the spherical dimples can produce a larger reduction of friction in mixed lubrication region, and reduce power loss significantly in the middle of the strokes. In addition, higher reduction percentages of average friction forces and wear are obtained for smaller crown height or larger axial width. PMID:28732042

Effects of CSR Generated from Upstream Bends in a Laser Plasma Storage Ring

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

Mitchell, C.; Qiang, J.; Venturini, M.

The recent proposal [1] of a Laser Plasma Storage Ring (LPSR) envisions the use of a laser-plasma (LP) acceleration module to inject an electron beam into a compact 500 MeV storage ring. Electron bunches generated by LP methods are naturally very short (tens of femtoseconds), presenting peak currents on the order of 10 kA or higher. Of obvious concern is the impact of collective effects and in particular Coherent Synchrotron Radiation (CSR) on the beam dynamics in the storage ring. Available simulation codes (e.g. Elegant [2]) usually include transient CSR effects but neglect the contribution of radiation emitted from trailingmore » magnets. In a compact storage ring, with dipole magnets close to each other, cross talking between different magnets could in principle be important.In this note we investigate this effect for the proposed LPSR and show that, in fact, this effect is relatively small. However our analysis also indicates that CSR effects in general would be quite strong and deserve a a careful study.« less

GPU-based low-level trigger system for the standalone reconstruction of the ring-shaped hit patterns in the RICH Cherenkov detector of NA62 experiment

NASA Astrophysics Data System (ADS)

Ammendola, R.; Biagioni, A.; Chiozzi, S.; Cretaro, P.; Cotta Ramusino, A.; Di Lorenzo, S.; Fantechi, R.; Fiorini, M.; Frezza, O.; Gianoli, A.; Lamanna, G.; Lo Cicero, F.; Lonardo, A.; Martinelli, M.; Neri, I.; Paolucci, P. S.; Pastorelli, E.; Piandani, R.; Piccini, M.; Pontisso, L.; Rossetti, D.; Simula, F.; Sozzi, M.; Vicini, P.

2017-03-01

This project aims to exploit the parallel computing power of a commercial Graphics Processing Unit (GPU) to implement fast pattern matching in the Ring Imaging Cherenkov (RICH) detector for the level 0 (L0) trigger of the NA62 experiment. In this approach, the ring-fitting algorithm is seedless, being fed with raw RICH data, with no previous information on the ring position from other detectors. Moreover, since the L0 trigger is provided with a more elaborated information than a simple multiplicity number, it results in a higher selection power. Two methods have been studied in order to reduce the data transfer latency from the readout boards of the detector to the GPU, i.e., the use of a dedicated NIC device driver with very low latency and a direct data transfer protocol from a custom FPGA-based NIC to the GPU. The performance of the system, developed through the FPGA approach, for multi-ring Cherenkov online reconstruction obtained during the NA62 physics runs is presented.

Mechanical end joint system for connecting structural column elements

NASA Technical Reports Server (NTRS)

Bush, Harold G. (Inventor); Mikulas, Martin M., Jr. (Inventor); Wallsom, Richard E. (Inventor)

1990-01-01

A mechanical end joint system is presented that eliminates the possibility of free movements between the joint halves during loading or vibration. Both node joint body (NJB) and column end joint body (CEJB) have cylindrical engaging ends. Each of these ends has an integral semicircular tongue and groove. The two joint halves are engaged transversely - the tongue of the NJB mating with the groove of the CEJB and vice versa. The joint system employs a spring loaded internal latch mechanism housed in the CEJB. During mating, this mechanism is pushed away from the NJB and enters the NJB when mating is completed. In order to lock the joint and add a preload across the tongue and groove faces, an operating ring collar is rotated through 45 deg causing an internal mechanism to compress a Belleville washer preload mechanism. This causes an equal and opposite force to be exerted on the latch bolt and the latch plunger. This force presses the two joint halves tightly together. In order to prevent inadvertent disassembly, a secondary lock is also engaged when the joint is closed. Plungers are carried in the operating ring collar. When the joint is closed, the plungers fall into tracks on the CEJB, which allows the joint to be opened only when the operating ring collar and plungers are pushed directly away from the joining end. One application of this invention is the rapid assembly and disassembly of diverse skeletal framework structures which is extremely important in many projects involving the exploration of space.

Ring and plasma - The enigmae of Enceladus

NASA Technical Reports Server (NTRS)

Haff, P. K.; Siscoe, G. L.; Eviatar, A.

1983-01-01

The E ring associated with the Kronian moon Enceladus has a lifetime of only a few thousand years against sputtering by slow corotating O ions. The existence of the ring implies the necessity for a continuous supply of matter. Possible particle source mechanisms on Enceladus include meteoroidal impact ejection and geysering. Estimates of ejection rates of particulate debris following small meteoroid impact are on the order of 3 x 10 to the -18th g/(sq cm sec), more than an order of magnitude too small to sustain the ring. A geyser source would need to generate a droplet supply at a rate of approximately 10 to the -16th g/(sq cm sec) in order to account for a stable ring. Enceladus and the ring particles also directly supply both plasma and vapor to space via sputtering. The absence of a 60 eV plasma at the Voyager 2 Enceladus L-shell crossing, such as might have been expected from sputtering, cannot be explained by absorption and moderation of plasma ions by ring particles, because the ring is too diffuse. Evidently, the effective sputtering yield in the vicinity of Enceladus is on the order of, or smaller than, 0.4, about an order of magnitude less than te calculated value. Small scale surface roughness may account for some of this discrepancy.

Biodegradation and photooxidation of crude oil under natural sunlight in the northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Bacosa, H. P.; Erdner, D.; Liu, Z.

2016-02-01

An enormous amount of oil was observed in the deep and surface waters of the northern Gulf of Mexico (nGoM) following the Deepwater Horizon (DWH) spill. While the oil degradation and bacterial communities in the deep-sea plume have been widely investigated, the effect of sunlight on oil and bacterial assemblages in surface waters have received less attention. In this study, we amended surface water collected near the DWH site with crude oil and/or Corexit dispersant and incubated under natural sunlight in the nGoM for 36 d in summer of 2013. The residual alkanes, polycyclic aromatic hydrocarbons (PAHs), and alkalyted PAHs were analyzed by GC-MS, and bacterial community was determined via pyrosequencing. The results show that n-alkane biodegradation rate constants (first order) were ca. ten-fold higher than the photooxidation rate constants. While biodegradation was characterized by a lag phase, photooxidation rate constants for the 2-3 ring and 4-5 ring PAHs, were 0.08-0.98 day-1 and 0.01-0.07 day-1, respectively. Compared to biodegradation, photooxidation increased the transformation of 4-5 ring PAHs by 70% and 3-4 ring alkylated PAHs by 36%. Sunlight significantly reduced bacterial diversity and a driver of shifts in bacterial community structure in oil and Corexit treatments. In amended treatments, sunlight increased the relative abundances of Alteromonas, Marinobacter, Labrenzia, Sandarakinotalea, Halomonas and Bartonella, while the dark treatments enriched Thalassobius, Winogradskyella, Alcanivorax, Formosa, Eubacterium, Erythrobacter, Natronocella, and Pseudomonas. This suggests that different bacteria are degrading the hydrocarbons in the dark and under light exposure. In a follow up study using DNA-Stable isotope probing (SIP), we identified the alkane and PAH degraders using 13C-labeled hexadecane and phenanthrene, respectively. The results of metagenomic and metatranscriptomic analyses in the light and dark incubations will be presented. For the first time, we demonstrated the effects of sunlight in structuring microbial communities oil polluted water. This study provides quantitative measures of oil degradation under relevant field conditions, and improves our understanding of the role of sunlight on the fate of spilled oil and microbial community composition in the nGoM.

(13)C NMR Studies, Molecular Order, and Mesophase Properties of Thiophene Mesogens.

PubMed

Veeraprakash, B; Lobo, Nitin P; Narasimhaswamy, T

2015-12-03

Three-ring mesogens with a core comprising thiophene linked to one phenyl ring directly and to the other via flexible ester are synthesized with terminal alkoxy chains to probe the mesophase properties and find the molecular order. The phenyl thiophene link in the core offers a comparison of the mesophase features with the molecular shape of the mesogen. The synthesized mesogens display enantiotropic polymesomorphism and accordingly nematic, smectic A, smectic C and smectic B mesophases are perceived depending upon the terminal chain length. For some of the homologues, monotropic higher order smectic phases such as smectic F and crystal E are also witnessed. The existence of polymesomorphism are originally observed by HOPM and DSC and further confirmed by powder X-ray diffraction studies. For the C8 homologue, high resolution solid state (13)C NMR spectroscopy is employed to find the molecular structure in the liquid crystalline phase and using the 2D SLF technique, the (13)C-(1)H dipolar couplings are extracted to calculate the order parameter. By comparing the ratio of local order of thiophene as well as phenyl rings, we establish the bent-core shape of the mesogen. Importantly, for assigning the carbon chemical shifts of the core unit of aligned C8 mesogen, the (13)C NMR measured in mesophase of the synthetic intermediate is employed. Thus, the proposed approach addresses the key step in the spectral assignment of target mesogens with the use of (13)C NMR data of mesomorphic intermediate.

Big Five Personality Factors and Facets as Predictors of Openness to Diversity.

PubMed

Han, Suejung; Pistole, M Carole

2017-11-17

Openness to diversity is a crucial component of cultural competence needed in the increasingly diversified modern society and a necessary condition for benefitting from diversity contacts and interventions (e.g., diversity training, cultural courses). Responding to the recent call for more research on personality and its relation to diversity outcomes, we examined the associations between Big Five personality (i.e., Openness to Experience, Agreeableness, Extraversion, Neuroticism, and Conscientiousness) higher order factors and lower order facets and universal-diverse orientation (i.e., open attitude of appreciating human universality and diversity; Miville et al., 1999 ). In the Study 1 (N = 338) web survey on Big Five factors, Openness to Experience and Agreeableness were associated with universal-diverse orientation significantly. In the Study 2 (N = 176) paper survey on both Big Five factors and facets, Openness to Experience, low Neuroticism, and Conscientiousness, and various lower-order facets of all the Big Five personality were associated with universal-diverse orientation significantly. Practical implications were suggested on how personality facets could be incorporated into current diversity interventions to enhance their effectiveness of promoting openness to diversity.

Annual growth bands in Hymenaea courbaril: implications for utilization in tropical paleoclimate reconstructions.

NASA Astrophysics Data System (ADS)

Westbrook, J. A.; Guilderson, T.; Colinvaux, P. A.; D'Arrigo, R.

2004-12-01

Instrumental records of environmental variables such as temperature and precipitation are necessary to understand climate patterns and variability. In general, such observations from the tropics do not exist prior to the late 19th century, and existing records contain large spatial and temporal gaps and are sparsely distributed. An important source of annual temperature and precipitation proxy-data comes from the regular annual growth rings of wood formed by trees. Tree growth rings occur in response to periodic seasonal changes in the environment. Although expansive and diverse in number and ecology, a vast majority of tropical trees do not produce distinct annual growth rings. Because of this, tropical dendrochronology and paleoclimate reconstructions have lagged behind their temperate and higher latitude cousins. Distinct secondary growth rings were investigated in a single individual of the tropical hardwood legume Hymenaea courbaril felled within the City of David, Republic of Panama. Rings that maintained circuitry were considered annual and were sampled for 14C. Radiocarbon values from the secondary growth rings from this specimen were compared with annual reference radiocarbon values from wood and air in North America, New Zealand and Germany. This comparison demonstrated that the secondary growth rings formed by H. courbaril were determined to be annual in nature in this one stem disk specimen. To confirm the consistency of the annual nature of the secondary growth rings in H. courbaril, nine (9) additional specimens were recovered from the small hamlet of San Carlos y Algarobbo in western Panama between the town of David and the cordillera approximately ~30km from the site of the first tree sample. Of the nine specimens, four were chosen for ring counts and isotope analyses. "Annual" rings were counted and samples corresponding to the equivalent time of the bomb-14C peak were sampled. In addition a small subset of years within one tree specimen were sub-annually sampled for d18O cellulose. Radiocarbon and 18Ocellulose are consistent with the secondary rings being annual. These results imply that H. courbaril may be suitable for extended paleoclimate reconstructions.

Readout of the atomtronic quantum interference device

NASA Astrophysics Data System (ADS)

Haug, Tobias; Tan, Joel; Theng, Mark; Dumke, Rainer; Kwek, Leong-Chuan; Amico, Luigi

2018-01-01

A Bose-Einstein condensate confined in ring shaped lattices interrupted by a weak link and pierced by an effective magnetic flux defines the atomic counterpart of the superconducting quantum interference device: the atomtronic quantum interference device (AQUID). In this paper, we report on the detection of current states in the system through a self-heterodyne protocol. Following the original proposal of the NIST and Paris groups, the ring-condensate many-body wave function interferes with a reference condensate expanding from the center of the ring. We focus on the rf AQUID which realizes effective qubit dynamics. Both the Bose-Hubbard and Gross-Pitaevskii dynamics are studied. For the Bose-Hubbard dynamics, we demonstrate that the self-heterodyne protocol can be applied, but higher-order correlations in the evolution of the interfering condensates are measured to readout of the current states of the system. We study how states with macroscopic quantum coherence can be told apart analyzing the noise in the time of flight of the ring condensate.

Morphological Diversity in Crystal Growth of l-Ascorbic Acid Dissolved in Methanol

NASA Astrophysics Data System (ADS)

Ito, Miho; Izui, Machiko; Yamazaki, Yoshihiro; Matsushita, Mitsugu

2003-06-01

Morphological diagram with respect to crystal growth of l-ascorbic acid (C6H8O6; so-called vitamin C) from methanol solution on a flat glass dish is presented. Varying humidity and initial concentration of l-ascorbic acid in methanol solution, the following three distinct kinds of growing patterns have been observed: homogeneous disk, concentric ring and dendrite. In addition, in higher concentration clearly faceted small single crystals grow in any humidity less than 90%. Crossovers from one pattern to another were observed, too.

Higher order mode couplers for normal conducting DORIS 5-cell cavities

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

Dewersteg, B.; Seesselberg, E.; Zolfaghari, A.

1985-10-01

The beam intensity of the DORIS e -e storage ring is limited to about 100 mA average circulation current as a result of instabilities driven by higher order rf cavity modes. Thus an investigation has been made of the higher order mode impedances of the DORIS rf accelerator cavities. These cavities are the same as the normally conducting inductively coupled 500 MHz 5-cell structures used in PETRA. The results of the investigation were applied for the construction of inductive and capacitive attenuation antennae corresponding to specific mode spectra and mode impedances. The antennae must fit into the existing 35 mmmore » pick up flanges of the cavities and in spite of these size and position limitations they must be efficient in reducing the shunt impedances of the dangerous modes.« less

Transient line starting analysis of the ultra-high speed PMSM

PubMed Central

Cheng, Wenjie; Li, Wei; Xiao, ling; Li, Ming; Tian, Yongsheng; Sun, Yanhua; Yu, Lie

2017-01-01

Aiming at the ultra high speed permanent magnet synchronous motor (PMSM) supported by gas foil bearings (GFBs), this paper calculates the transient line starting of the motor. Firstly, the start effect of the rotor composed of cylindrical PM and stainless steel sleeve is studied. Then, in order to enhance the start torque, copper ring, nickel ring and copper squirrel-cage are introduced in the rotor and their start effect are analysed, respectively. It can be found that the rotor including nickel ring can be accelerated to set speed, but all the other rotors are failed due to the higher PM and braking torques. It can be concluded that some material owning slight large relative permeability can be applied in the rotor to reduce the PM field and contribute to start by using the line-start method. PMID:28105384

Figures of equilibrium inside a gravitating ring and the limiting oblateness of elliptical galaxies

NASA Astrophysics Data System (ADS)

Kondratyev, B. P.; Trubitsyna, N. G.; Kireeva, E. N.

2016-05-01

A new class of figures of equilibrium for a rotating gravitating fluid located inside a gravitating ring or torus is studied. These figures form a family of sequences of generalized oblate spheroids, in which there is for any value of the tidal parameter α in the interval 0 ≤ 0 ≤slant α /{π Gρ } ≤slant 0.1867 ≤ 0.1867 a sequence of spheroids with oblatenesses emin ( α) ≤ e ≤ e max ( α). A series of classicalMaclaurin spheroids from a sphere to a flat disk is obtained for α = 0. At intermediate values 0 < α ≤ α max, there are two limiting non-rotating spheroids in each sequence. When α = α max, the sequence degenerates into a single non-rotating spheroid with e cr ≈ 0.9600, corresponding to the maximum oblateness of E7 elliptical galaxies. The second part of the paper considers the influence of rings of dark matter on the dynamics of elliptical galaxies. It is proposed that the equilibrium of an oblate isolated non-rotating galaxy is unstable, and it cannot be supported purely by anisotropy of the stellar velocity dispersion. A ring of dark matter can stabilize a weakly rotating galaxy, supplementing standard dynamical models for such stellar systems. In order for a galaxy to acquire appreciable oblateness, the mass of the ring must be an order of magnitude higher than the mass of the galaxy itself, consistent with the ratios of the masses of dark and baryonic matter in the Universe. The influence of massive external rings could shed light on the existence of galaxies with the critical oblateness E7.

Generation of Earth's First-Order Biodiversity Pattern

NASA Astrophysics Data System (ADS)

Krug, Andrew Z.; Jablonski, David; Valentine, James W.; Roy, Kaustuv

2009-02-01

The first-order biodiversity pattern on Earth today and at least as far back as the Paleozoic is the latitudinal diversity gradient (LDG), a decrease in richness of species and higher taxa from the equator to the poles. LDGs are produced by geographic trends in origination, extinction, and dispersal over evolutionary timescales, so that analyses of static patterns will be insufficient to reveal underlying processes. The fossil record of marine bivalve genera, a model system for the analysis of biodiversity dynamics over large temporal and spatial scales, shows that an origination and range-expansion gradient plays a major role in generating the LDG. Peak origination rates and peak diversities fall within the tropics, with range expansion out of the tropics the predominant spatial dynamic thereafter. The origination-diversity link occurs even in a "contrarian" group whose diversity peaks at midlatitudes, an exception proving the rule that spatial variations in origination are key to latitudinal diversity patterns. Extinction rates are lower in polar latitudes (≥60°) than in temperate zones and thus cannot create the observed gradient alone. They may, however, help to explain why origination and immigration are evidently damped in higher latitudes. We suggest that species require more resources in higher latitudes, for the seasonality of primary productivity increases by more than an order of magnitude from equatorial to polar regions. Higher-latitude species are generalists that, unlike potential immigrants, are adapted to garner the large share of resources required for incumbency in those regions. When resources are opened up by extinctions, lineages spread chiefly poleward and chiefly through speciation.

Generation of Earth's first-order biodiversity pattern.

PubMed

Krug, Andrew Z; Jablonski, David; Valentine, James W; Roy, Kaustuv

2009-01-01

The first-order biodiversity pattern on Earth today and at least as far back as the Paleozoic is the latitudinal diversity gradient (LDG), a decrease in richness of species and higher taxa from the equator to the poles. LDGs are produced by geographic trends in origination, extinction, and dispersal over evolutionary timescales, so that analyses of static patterns will be insufficient to reveal underlying processes. The fossil record of marine bivalve genera, a model system for the analysis of biodiversity dynamics over large temporal and spatial scales, shows that an origination and range-expansion gradient plays a major role in generating the LDG. Peak origination rates and peak diversities fall within the tropics, with range expansion out of the tropics the predominant spatial dynamic thereafter. The origination-diversity link occurs even in a "contrarian" group whose diversity peaks at midlatitudes, an exception proving the rule that spatial variations in origination are key to latitudinal diversity patterns. Extinction rates are lower in polar latitudes (> or =60 degrees ) than in temperate zones and thus cannot create the observed gradient alone. They may, however, help to explain why origination and immigration are evidently damped in higher latitudes. We suggest that species require more resources in higher latitudes, for the seasonality of primary productivity increases by more than an order of magnitude from equatorial to polar regions. Higher-latitude species are generalists that, unlike potential immigrants, are adapted to garner the large share of resources required for incumbency in those regions. When resources are opened up by extinctions, lineages spread chiefly poleward and chiefly through speciation.

Construction of substituted benzene rings by palladium-catalyzed direct cross-coupling of olefins: a rapid synthetic route to 1,4-naphthoquinone and its derivatives.

PubMed

Hu, Peng; Huang, Shijun; Xu, Jing; Shi, Zhang-Jie; Su, Weiping

2011-10-10

Ring the changes: the direct cross-coupling of electron-deficient 1,4-benzoquinone or its derivatives with electron-rich alkyl vinyl ethers proceeds in a tandem manner to produce substituted benzene rings with good selectivity and in good to excellent yields. The reaction has the potential for the rapid synthesis of diverse substituted benzene rings as it is not limited by substituent effects. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrodynamic characterisitcs measurements of higher order modes in S-band cavity

NASA Astrophysics Data System (ADS)

Donetsky, R.; Lalayan, M.; Sobenin, N. P.; Orlov, A.; Bulygin, A.

2017-12-01

The 800 MHz superconducting cavities with grooved beam pipes were suggested as one of the harmonic cavities design options for High Luminosity LHC project. Cavity simulations were carried out and scaled aluminium prototype having operational mode frequency of 2400 MHz was manufactured for testing the results of simulations. The experimental measurements of transverse shunt impedance with error estimation for higher order modes TM 110 and TE 111 for S-band elliptical cavity were done. The experiments using dielectric and metallic spherical beads and with ring probe were carried out. The Q-factor measurements for two-cell structure and array of two cells were carried out.

Phylogenetic diversity of Archaea in the intestinal tract of termites from different lineages.

PubMed

Shi, Yu; Huang, Zhou; Han, Shuai; Fan, Shuo; Yang, Hong

2015-08-01

Termites are among the few arthropods that emit methane to the atmosphere, which is a significant source of global greenhouse gas due to their huge biomass on earth. In this study, phylogenetic diversity of Archaea of five termite species from different lineages were analyzed based on 16S rRNA genes. Archaea associated with wood-feeding lower termite, R. chinensis were exclusively Methanobrevibacter in the order Methanobacteriales. This type of methanogens was also found in Nasutitermes sp. and Microcerotermes sp. but not in the fungus-cultivating termites, Odontotermes formosanus and Macrotermes barneyi, which harbor Archaea of the order Methanoplasmatales and Methanosarcinales in their guts. Archaeal diversity of wood-feeding higher termites was higher than wood-feeding lower termites. The highest archaeal diversity was found in Nasutitermes sp. In addition to methanogens affiliated with the orders Methanobacteriales, Methanomicrobiales, and Methanoplasmatales, 37% of archaeal clones were affiliated with non-methanogenic Thaumarchaeota. The results of this study will be significant for further understanding of symbiotic relationship between intestinal microbiota and termites. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaporation of sessile drops containing colloidal rods: coffee-ring and order-disorder transition.

PubMed

Dugyala, Venkateshwar Rao; Basavaraj, Madivala G

2015-03-05

Liquid drops containing insoluble solutes when dried on solid substrates leave distinct ring-like deposits at the periphery or along the three-phase contact line-a phenomena popularly known as the coffee-ring or the coffee stain effect. The formation of such rings as well as their suppression is shown to have applications in particle separation and disease diagnostics. We present an experimental study of the evaporation of sessile drops containing silica rods to elucidate the structural arrangement of particles in the ring, an effect of the addition of surfactant and salt. To this end, the evaporation of aqueous sessile drops containing model rod-like silica particles of aspect ratio ranging from ∼4 to 15 on a glass slide is studied. We first show that when the conditions such as (1) solvent evaporation, (2) nonzero contact angle, (3) contact line pinning, (4) no surface tension gradient driven flow, and (5) repulsive particle-particle/particle-substrate interactions, that are necessary for the formation of the coffee-ring are met, the suspension drops containing silica rods upon evaporation leave a ring-like deposit. A closer examination of the ring deposits reveals that several layers of silica rods close to the edge of the drop are ordered such that the major axis of the rods are oriented parallel to the contact line. After the first few layers of ordered arrangement of particles, a random arrangement of particles in the drop interior is observed indicating an order-disorder transition in the ring. We monitor the evolution of the ring width and particle velocity during evaporation to elucidate the mechanism of the order-disorder transition. Moreover, when the evaporation rate is lowered, the ordering of silica rods is observed to extend over large areas. We demonstrate that the nature of the deposit can be tuned by the addition of a small quantity of surfactant or salt.

Interactive effects of PAHs with different rings and As on their uptake, transportation, and localization in As hyperaccumulator.

PubMed

Liao, Xiaoyong; Wu, Zeying; Ma, Xu; Gong, Xuegang; Yan, Xiulan

2017-11-01

In order to illuminate the mechanism of the interaction of polycyclic aromatic hydrocarbon (PAH) with different benzene rings and arsenic (As) in As hyperaccumulator, Pteris vittata L., the uptakes of PAHs were investigated using hydroponics simulation and localizations of PAHs in the plant were determined using two-photon laser scanning confocal microscopy (TPLSCM). The results showed that the total As concentration in different parts of P. vittata decreased in the presence of PAHs with increased numbers of benzene rings: 38.0-47.4% for benzo(a)pyrene (BaP, five rings), 20.5-35.9% for pyrene (PYR, four rings), and 13.7-16.6% for fluorine (FLU, three rings). BaP and PYR concentrations increased, while FLU concentration decreased in the presence of As. The results of TPLSCM revealed that PAHs distributed in epidermal cells of roots, xylem, and endothelial cells of rachis, epidermis, and stomatal cells of pinnae; however, the fluorescence intensity of BaP and PYR were higher than FLU significantly in plant. This study provided important basis to further research on interactive effects of PAHs and As in the P. vittata. These findings were important to understand the mechanisms of PAH and As translocation and distribution by P. vittata.

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

Shenoy, G. K.; Rohlsberger, R.; X-Ray Science Division

From the beginning of its discovery the Moessbauer effect has continued to be one of the most powerful tools with broad applications in diverse areas of science and technology. With the advent of synchrotron radiation sources such as the Advanced Photon Source (APS), the European Synchrotron Radiation Facility (ESRF) and the Super Photon Ring-8 (SPring-8), the tool has enlarged its scope and delivered new capabilities. The popular techniques most generally used in the field of materials physics, chemical physics, geoscience, and biology are hyperfine spectroscopy via elastic nuclear forward scattering (NFS), vibrational spectroscopy via nuclear inelastic scattering (NRIXS), and, tomore » a lesser extent, diffusional dynamics from quasielastic nuclear forward scattering (QNFS). As we look ahead, new storage rings with enhanced brilliance such as PETRA-III under construction at DESY, Hamburg, and PEP-III in its early design stage at SLAC, Stanford, will provide new and unique science opportunities. In the next two decades, x-ray free-electron lasers (XFELs), based both on self-amplified spontaneous emission (SASE-XFELs) and a seed (SXFELs), with unique time structure, coherence and a five to six orders higher average brilliance will truly revolutionize nuclear resonance applications in a major way. This overview is intended to briefly address the unique radiation characteristics of new sources on the horizon and to provide a glimpse of scientific prospects and dreams in the nuclear resonance field from the new radiation sources. We anticipate an expanded nuclear resonance research activity with applications such as spin and phonon mapping of a single nanostructure and their assemblies, interfaces, and surfaces; spin dynamics; nonequilibrium dynamics; photochemical reactions; excited-state spectroscopy; and nonlinear phenomena.« less

Nematode-Trapping Fungi.

PubMed

Jiang, Xiangzhi; Xiang, Meichun; Liu, Xingzhong

2017-01-01

Nematode-trapping fungi are a unique and intriguing group of carnivorous microorganisms that can trap and digest nematodes by means of specialized trapping structures. They can develop diverse trapping devices, such as adhesive hyphae, adhesive knobs, adhesive networks, constricting rings, and nonconstricting rings. Nematode-trapping fungi have been found in all regions of the world, from the tropics to Antarctica, from terrestrial to aquatic ecosystems. They play an important ecological role in regulating nematode dynamics in soil. Molecular phylogenetic studies have shown that the majority of nematode-trapping fungi belong to a monophyletic group in the order Orbiliales (Ascomycota). Nematode-trapping fungi serve as an excellent model system for understanding fungal evolution and interaction between fungi and nematodes. With the development of molecular techniques and genome sequencing, their evolutionary origins and divergence, and the mechanisms underlying fungus-nematode interactions have been well studied. In recent decades, an increasing concern about the environmental hazards of using chemical nematicides has led to the application of these biological control agents as a rapidly developing component of crop protection.

Discovery of 8-Membered Ring Sulfonamides as Inhibitors of Oncogenic Mutant Isocitrate Dehydrogenase 1.

PubMed

Law, Jason M; Stark, Sebastian C; Liu, Ke; Liang, Norah E; Hussain, Mahmud M; Leiendecker, Matthias; Ito, Daisuke; Verho, Oscar; Stern, Andrew M; Johnston, Stephen E; Zhang, Yan-Ling; Dunn, Gavin P; Shamji, Alykhan F; Schreiber, Stuart L

2016-10-13

Evidence suggests that specific mutations of isocitrate dehydrogenases 1 and 2 (IDH1/2) are critical for the initiation and maintenance of certain tumor types and that inhibiting these mutant enzymes with small molecules may be therapeutically beneficial. In order to discover mutant allele-selective IDH1 inhibitors with chemical features distinct from existing probes, we screened a collection of small molecules derived from diversity-oriented synthesis. The assay identified compounds that inhibit the IDH1-R132H mutant allele commonly found in glioma. Here, we report the discovery of a potent (IC 50 = 50 nM) series of IDH1-R132H inhibitors having 8-membered ring sulfonamides as exemplified by the compound BRD2879. The inhibitors suppress ( R )-2-hydroxyglutarate production in cells without apparent toxicity. Although the solubility and pharmacokinetic properties of the specific inhibitor BRD2879 prevent its use in vivo , the scaffold presents a validated starting point for the synthesis of future IDH1-R132H inhibitors having improved pharmacological properties.

On the design of a miniature haptic ring for cutaneous force feedback using shape memory alloy actuators

NASA Astrophysics Data System (ADS)

Hwang, Donghyun; Lee, Jaemin; Kim, Keehoon

2017-10-01

This paper proposes a miniature haptic ring that can display touch/pressure and shearing force to the user’s fingerpad. For practical use and wider application of the device, it is developed with the aim of achieving high wearability and mobility/portability as well as cutaneous force feedback functionality. A main body of the device is designed as a ring-shaped lightweight structure with a simple driving mechanism, and thin shape memory alloy (SMA) wires having high energy density are applied as actuating elements. Also, based on a band-type wireless control unit including a wireless data communication module, the whole device could be realized as a wearable mobile haptic device system. These features enable the device to take diverse advantages on functional performances and to provide users with significant usability. In this work, the proposed miniature haptic ring is systematically designed, and its working performances are experimentally evaluated with a fabricated functional prototype. The experimental results obviously demonstrate that the proposed device exhibits higher force-to-weight ratio than conventional finger-wearable haptic devices for cutaneous force feedback. Also, it is investigated that operational performances of the device are strongly influenced by electro-thermomechanical behaviors of the SMA actuator. In addition to the experiments for performance evaluation, we conduct a preliminary user test to assess practical feasibility and usability based on user’s qualitative feedback.

Few-cycle optical rogue waves: complex modified Korteweg-de Vries equation.

PubMed

He, Jingsong; Wang, Lihong; Li, Linjing; Porsezian, K; Erdélyi, R

2014-06-01

In this paper, we consider the complex modified Korteweg-de Vries (mKdV) equation as a model of few-cycle optical pulses. Using the Lax pair, we construct a generalized Darboux transformation and systematically generate the first-, second-, and third-order rogue wave solutions and analyze the nature of evolution of higher-order rogue waves in detail. Based on detailed numerical and analytical investigations, we classify the higher-order rogue waves with respect to their intrinsic structure, namely, fundamental pattern, triangular pattern, and ring pattern. We also present several new patterns of the rogue wave according to the standard and nonstandard decomposition. The results of this paper explain the generalization of higher-order rogue waves in terms of rational solutions. We apply the contour line method to obtain the analytical formulas of the length and width of the first-order rogue wave of the complex mKdV and the nonlinear Schrödinger equations. In nonlinear optics, the higher-order rogue wave solutions found here will be very useful to generate high-power few-cycle optical pulses which will be applicable in the area of ultrashort pulse technology.

Identifying resonance frequency deviations for high order nano-wire ring resonator filters based on a coupling strength variation

NASA Astrophysics Data System (ADS)

Park, Sahnggi; Kim, Kap-Joong; Kim, Duk-Jun; Kim, Gyungock

2009-02-01

Third order ring resonators are designed and their resonance frequency deviations are analyzed experimentally by processing them with E-beam lithography and ICP etching in a CMOS nano-Fabrication laboratory. We developed a reliable method to identify and reduce experimentally the degree of deviation of each ring resonance frequency before completion of the fabrication process. The identified deviations can be minimized by the way to be presented in this paper. It is expected that this method will provide a significant clue to make a high order multi-channel ring resonators.

Non-Linear Dynamics of Saturn's Rings

NASA Astrophysics Data System (ADS)

Esposito, L. W.

2015-12-01

Non-linear processes can explain why Saturn's rings are so active and dynamic. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average: 2-10x is possible. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like 'straw' that can explain the halo structure and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; Surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km); We propose 'straw', as observed ny Cassini cameras. Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing. Ring dynamics and history implications: Moon-triggered clumping at perturbed regions in Saturn's rings creates both high velocity dispersion and large aggregates at these distances, explaining both small and large particles observed there. This confirms the triple architecture of ring particles: a broad size distribution of particles; these aggregate into temporary rubble piles; coated by a regolith of dust. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating the Markov chain as an asymmetric random walk with reflecting boundaries allows us to determine the power law index from results of numerical simulations in the tidal environment surrounding Saturn. Aggregates can explain many dynamic aspects of the rings and can renew rings by shielding and recycling the material within them, depending on how long the mass is sequestered. We can ask: Are Saturn's rings a chaotic non-linear driven system?

Drug-likeness analysis of traditional Chinese medicines: 2. Characterization of scaffold architectures for drug-like compounds, non-drug-like compounds, and natural compounds from traditional Chinese medicines.

PubMed

Tian, Sheng; Li, Youyong; Wang, Junmei; Xu, Xiaojie; Xu, Lei; Wang, Xiaohong; Chen, Lei; Hou, Tingjun

2013-01-21

In order to better understand the structural features of natural compounds from traditional Chinese medicines, the scaffold architectures of drug-like compounds in MACCS-II Drug Data Report (MDDR), non-drug-like compounds in Available Chemical Directory (ACD), and natural compounds in Traditional Chinese Medicine Compound Database (TCMCD) were explored and compared. First, the different scaffolds were extracted from ACD, MDDR and TCMCD by using three scaffold representations, including Murcko frameworks, Scaffold Tree, and ring systems with different complexity and side chains. Then, by examining the accumulative frequency of the scaffolds in each dataset, we observed that the Level 1 scaffolds of the Scaffold Tree offer advantages over the other scaffold architectures to represent the scaffold diversity of the compound libraries. By comparing the similarity of the scaffold architectures presented in MDDR, ACD and TCMCD, structural overlaps were observed not only between MDDR and TCMCD but also between MDDR and ACD. Finally, Tree Maps were used to cluster the Level 1 scaffolds of the Scaffold Tree and visualize the scaffold space of the three datasets. The analysis of the scaffold architectures of MDDR, ACD and TCMCD shows that, on average, drug-like molecules in MDDR have the highest diversity while natural compounds in TCMCD have the highest complexity. According to the Tree Maps, it can be observed that the Level 1 scaffolds present in MDDR have higher diversity than those presented in TCMCD and ACD. However, some representative scaffolds in MDDR with high frequency show structural similarities to those in TCMCD and ACD, suggesting that some scaffolds in TCMCD and ACD may be potentially drug-like fragments for fragment-based and de novo drug design.

Drug-likeness analysis of traditional Chinese medicines: 2. Characterization of scaffold architectures for drug-like compounds, non-drug-like compounds, and natural compounds from traditional Chinese medicines

PubMed Central

2013-01-01

Background In order to better understand the structural features of natural compounds from traditional Chinese medicines, the scaffold architectures of drug-like compounds in MACCS-II Drug Data Report (MDDR), non-drug-like compounds in Available Chemical Directory (ACD), and natural compounds in Traditional Chinese Medicine Compound Database (TCMCD) were explored and compared. Results First, the different scaffolds were extracted from ACD, MDDR and TCMCD by using three scaffold representations, including Murcko frameworks, Scaffold Tree, and ring systems with different complexity and side chains. Then, by examining the accumulative frequency of the scaffolds in each dataset, we observed that the Level 1 scaffolds of the Scaffold Tree offer advantages over the other scaffold architectures to represent the scaffold diversity of the compound libraries. By comparing the similarity of the scaffold architectures presented in MDDR, ACD and TCMCD, structural overlaps were observed not only between MDDR and TCMCD but also between MDDR and ACD. Finally, Tree Maps were used to cluster the Level 1 scaffolds of the Scaffold Tree and visualize the scaffold space of the three datasets. Conclusion The analysis of the scaffold architectures of MDDR, ACD and TCMCD shows that, on average, drug-like molecules in MDDR have the highest diversity while natural compounds in TCMCD have the highest complexity. According to the Tree Maps, it can be observed that the Level 1 scaffolds present in MDDR have higher diversity than those presented in TCMCD and ACD. However, some representative scaffolds in MDDR with high frequency show structural similarities to those in TCMCD and ACD, suggesting that some scaffolds in TCMCD and ACD may be potentially drug-like fragments for fragment-based and de novo drug design. PMID:23336706

Particle–hole ring diagrams for fermions in two dimensions

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

Kaiser, N., E-mail: nkaiser@ph.tum.de

2014-11-15

The set of particle–hole ring diagrams for a many-fermion system in two dimensions is studied. The complex-valued polarization function is derived in detail and shown to be expressible in terms of square-root functions. For a contact-interaction the perturbative contributions to the energy per particle Ē(k{sub f}) are calculated in a closed analytical form from third up to twelfth order. The resummation of the particle–hole ring diagrams to all orders is studied and a pronounced dependence on the dimensionless coupling parameter α is found. There is a substantial difference between the complete ring-sum with all exchange-type diagrams included and the standardmore » resummation of the leading n-ring diagrams only. The spin factor S{sub n}(g) associated to the nth order ring diagrams is derived for arbitrary spin-degeneracy g.« less

An artificial molecular pump

NASA Astrophysics Data System (ADS)

Cheng, Chuyang; McGonigal, Paul R.; Schneebeli, Severin T.; Li, Hao; Vermeulen, Nicolaas A.; Ke, Chenfeng; Stoddart, J. Fraser

2015-06-01

Carrier proteins consume fuel in order to pump ions or molecules across cell membranes, creating concentration gradients. Their control over diffusion pathways, effected entirely through noncovalent bonding interactions, has inspired chemists to devise artificial systems that mimic their function. Here, we report a wholly artificial compound that acts on small molecules to create a gradient in their local concentration. It does so by using redox energy and precisely organized noncovalent bonding interactions to pump positively charged rings from solution and ensnare them around an oligomethylene chain, as part of a kinetically trapped entanglement. A redox-active viologen unit at the heart of a dumbbell-shaped molecular pump plays a dual role, first attracting and then repelling the rings during redox cycling, thereby enacting a flashing energy ratchet mechanism with a minimalistic design. Our artificial molecular pump performs work repetitively for two cycles of operation and drives rings away from equilibrium toward a higher local concentration.

Influence of plasma beta on the generation of lower hybrid and whistler waves by an ion velocity ring distribution

DOE PAGES

Winske, D.; Daughton, W.

2015-02-02

We present results of three-dimensional electromagnetic particle-in-cell simulations of the lower hybrid ion ring instability, similar to our earlier results [D. Winske and W. Daughton, Phys. Plasma, 19, 072109, 2012], but at higher electron beta (βe = ratio of electron thermal pressure to magnetic pressure = 0.06, rather than at 0.006) with Ti = Te. At higher electron beta the level of lower hybrid waves at saturation normalized to the ion thermal energy (βi = 0.06 also) is only slightly smaller, but the corresponding magnetic fluctuations are about an order of magnitude larger, consistent with linear theory. After saturation, themore » waves evolve into whistler waves, through a number of possible mechanisms, with an average growth rate considerably smaller than the linear growth rate of the lower hybrid waves, to a peak fluctuation level that is about 20% above the lower hybrid wave saturation level. The ratio of the peak magnetic fluctuations associated with the whistler waves relative to those of the saturated lower hybrid waves, the ratio of the nonlinear growth rate of whistlers relative to the linear growth rate of lower hybrid waves, the amount of energy extracted from the ring and the amount of heating of the background ions and electrons are comparable to those in the lower electron beta 3-D simulation. This suggests that even at higher electron beta, the linear and nonlinear physics of the lower hybrid ion ring instability is dominated by electrostatic, wave-particle rather than wave-wave interactions.« less

The Polycomb proteins RING1B and EZH2 repress the tumoral pro-inflammatory function in metastasizing primary cutaneous squamous cell carcinoma.

PubMed

Hernández-Ruiz, Eugenia; Toll, Agustí; García-Diez, Irene; Andrades, Evelyn; Ferrandiz-Pulido, Carla; Masferrer, Emili; Yébenes, Mireia; Jaka, Ane; Gimeno, Javier; Gimeno, Ramón; García-Patos, Vicenç; Pujol, Ramón M; Hernández-Muñoz, Inmaculada

2018-03-08

Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy in humans and approximately 5% metastasize, usually to regional lymph nodes. Epigenetic regulation of gene expression may allow tumoral cells to acquire new functions in order to escape from the primary tumor. The aim of this study was to investigate the expression and function of proteins of the Polycomb family of epigenetic regulators in the metastatic process of cSCC. A higher expression of RING1B and EZH2 was detected by immunohistochemistry in a series of primary cSCC tumors that metastasized (MSCCs) when compared with non-metastasizing cSCCs (non-MSCCs). Stable downregulation of RING1B and EZH2 in cSCC cells results in enhanced expression of inflammatory cytokines and activation of the NF-κB signaling pathway. Accordingly, non-MSCCs display higher levels of membranous pS176-inhibitor of NF-kB kinase, and their stroma is enriched in neutrophils and eosinophils when compared with MSCCs. In vitro, hematopoietic cells exhibit a substantial migratory response to supernatants from Polycomb-depleted cSCC cells. Altogether, these data indicate that RING1B and EZH2 repress the innate inflammatory cSCC function and impair tumor immunosurveillance and suggest that patients with high-risk cSCCs could benefit from clinical therapies addressed to harness the immune response.

Wood anatomical analysis of Alnus incana and Betula pendula injured by a debris-flow event.

PubMed

Arbellay, Estelle; Stoffel, Markus; Bollschweiler, Michelle

2010-10-01

Vessel chronologies in ring-porous species have been successfully employed in the past to extract the climate signal from tree rings. Environmental signals recorded in vessels of ring-porous species have also been used in previous studies to reconstruct discrete events of drought, flooding and insect defoliation. However, very little is known about the ability of diffuse-porous species to record environmental signals in their xylem cells. Moreover, time series of wood anatomical features have only rarely been used to reconstruct former geomorphic events. This study was therefore undertaken to characterize the wood anatomical response of diffuse-porous Alnus incana (L.) Moench and Betula pendula Roth to debris-flow-induced wounding. Tree microscopic response to wounding was assessed through the analysis of wood anatomical differences between injured rings formed in the debris-flow event year and uninjured rings formed in the previous year. The two ring types were examined close and opposite to the injury in order to determine whether wound effects on xylem cells decrease with increasing tangential distance from the injury. Image analysis was used to measure vessel parameters as well as fiber and parenchyma cell (FPC) parameters. The results of this study indicate that injured rings are characterized by smaller vessels as compared with uninjured rings. By contrast, FPC parameters were not found to significantly differ between injured and uninjured rings. Vessel and FPC parameters mainly remained constant with increasing tangential distance from the injury, except for a higher proportion of vessel lumen area opposite to the injury within A. incana. This study highlights the existence of anatomical tree-ring signatures-in the form of smaller vessels-related to past debris-flow activity and addresses a new methodological approach to date injuries inflicted on trees by geomorphic processes.

Diversity time-period and diversity-time-area relationships exemplified by the human microbiome.

PubMed

Ma, Zhanshan Sam

2018-05-08

We extend the ecological laws of species-time relationship (STR) and species-time-area relationship (STAR) to general diversity time-period relationship (DTR) and diversity-time-area relationship (DTAR), and test the extensions with the human vaginal microbiome datasets by building 1460 DTR/DTAR models. Our extensions were inspired by the observation that Hill numbers, well regarded as the most appropriate measure of alpha-diversity and also particularly suitable for multiplicative beta-diversity partitioning, are actually in the units of effective species, and therefore, should be able to substitute for species in the STR and STAR. We found that the traditional power law (PL) model is only applicable for DTR at diversity order zero (i.e., species richness); at higher diversity orders (q = 1-4), the power law with exponent cutoff (PLEC) and power law with inverse exponent cutoff (PLIEC) are more appropriate. In particular, PLEC has an advantage over PLIEC in predicting maximal accumulation diversity (MAD) over time. In fact, with the DTR extensions, we can construct DTR and MAD profiles. To the best of our knowledge, this is the first comprehensive investigation of the DTR/DTAR in human microbiome. Methodologically, our DTR/DTAR profiles can characterize general diversity scaling beyond species richness, covering both alpha- and beta-diversity regimes across different diversity orders.

The Three-Ring Circus of Academia: How to Become the Ringmaster

ERIC Educational Resources Information Center

Toews, Michelle L.; Yazedjian, Ani

2007-01-01

The three-ring circus of academia is made up of research, teaching, and service. It is also characterized by continuous action that must be facilitated by the academic ringmaster. Academic life is more difficult than most anticipate because the responsibilities are time-consuming, diverse, and conflicting. Therefore, this article focuses on…

High numerical aperture projection system for extreme ultraviolet projection lithography

DOEpatents

Hudyma, Russell M.

2000-01-01

An optical system is described that is compatible with extreme ultraviolet radiation and comprises five reflective elements for projecting a mask image onto a substrate. The five optical elements are characterized in order from object to image as concave, convex, concave, convex, and concave mirrors. The optical system is particularly suited for ring field, step and scan lithography methods. The invention uses aspheric mirrors to minimize static distortion and balance the static distortion across the ring field width which effectively minimizes dynamic distortion. The present invention allows for higher device density because the optical system has improved resolution that results from the high numerical aperture, which is at least 0.14.

Intrinsic bioremediation potential of a chronically polluted marine coastal area.

PubMed

Catania, Valentina; Santisi, Santina; Signa, Geraldina; Vizzini, Salvatrice; Mazzola, Antonio; Cappello, Simone; Yakimov, Michail M; Quatrini, Paola

2015-10-15

A microbiological survey of the Priolo Bay (eastern coast of Sicily, Ionian Sea), a chronically polluted marine coastal area, was carried out in order to discern its intrinsic bioremediation potential. Microbiological analysis, 16S rDNA-based DGGE fingerprinting and PLFAs analysis were performed on seawater and sediment samples from six stations on two transects. Higher diversity and variability among stations was detected by DGGE in sediment than in water samples although seawater revealed higher diversity of culturable hydrocarbon-degrading bacteria. The most polluted sediment hosted higher total bacterial diversity and higher abundance and diversity of culturable HC degraders. Alkane- and PAH-degrading bacteria were isolated from all stations and assigned to Alcanivorax, Marinobacter, Thalassospira, Alteromonas and Oleibacter (first isolation from the Mediterranean area). High total microbial diversity associated to a large selection of HC degraders is believed to contribute to natural attenuation of the area, provided that new contaminant contributions are avoided. Copyright © 2015 Elsevier Ltd. All rights reserved.

New Developments on the PSR Instability

NASA Astrophysics Data System (ADS)

Macek, Robert

2000-04-01

A strong, fast, transverse instability has long been observed at the Los Alamos Proton Storage Ring (PSR) where it is a limiting factor on peak intensity. Most of the characteristics and experimental data are consistent with a two-stream instability (e-p) arising from coupled oscillations of the proton beam and an electron cloud. In past operations, where the average intensity was limited by beam losses, the instability was controlled by sufficient rf voltage in the ring. The need for higher beam intensity has motivated new work to better understand and control the instability. Results will be presented from studies of the production and characteristics of the electron cloud at various locations in the ring for both stable and unstable beams and suppression of electron cloud generation by TiN coatings. Studies of additional or alternate controls include application of dual harmonic rf, damping of the instability by higher order multipoles, damping by X,Y coupling from skew quadrupoles and the use of inductive inserts to compensate longitudinal space charge forces. Use of a skew quadrupole, heated inductive inserts and higher rf voltage from a refurbished rf buncher has enabled the PSR to accumulate stable beam intensity up to 9.7 micro-Coulombs (6 E13 protons) per macropulse, a significant increase (60over the previous maximum of 6 micro-Coulombs (3.7 E13 protons). However, slow losses were rather high and must be reduced for routine operation at repetition rates of 20 Hz or higher.

In silico and experimental methods revealed highly diverse bacteria with quorum sensing and aromatics biodegradation systems--a potential broad application on bioremediation.

PubMed

Huang, Yili; Zeng, Yanhua; Yu, Zhiliang; Zhang, Jing; Feng, Hao; Lin, Xiuchun

2013-11-01

Phylogenetic overlaps between aromatics-degrading bacteria and acyl-homoserine-lactone (AHL) or autoinducer (AI) based quorum-sensing (QS) bacteria were evident in literatures; however, the diversity of bacteria with both activities had never been finely described. In-silico searching in NCBI genome database revealed that more than 11% of investigated population harbored both aromatic ring-hydroxylating-dioxygenase (RHD) gene and AHL/AI-synthetase gene. These bacteria were distributed in 10 orders, 15 families, 42 genus and 78 species. Horizontal transfers of both genes were common among them. Using enrichment and culture dependent method, 6 Sphingomonadales and 4 Rhizobiales with phenanthrene- or pyrene-degrading ability and AHL-production were isolated from marine, wetland and soil samples. Thin-layer-chromatography and gas-chromatography-mass-spectrum revealed that these Sphingomonads produced various AHL molecules. This is the first report of highly diverse bacteria that harbored both aromatics-degrading and QS systems. QS regulation may have broad impacts on aromatics biodegradation, and would be a new angle for developing bioremediation technology. Copyright © 2013 Elsevier Ltd. All rights reserved.

Reinterpreting the Sharp Edges of Planetary Rings

NASA Astrophysics Data System (ADS)

Rimlinger, Thomas; Hamilton, Douglas P.; Hahn, Joseph M.

2016-10-01

Narrow ringlets are found throughout the Solar System and are typically 1-100 km wide. Angular momentum, L, is the key to understanding how narrow rings remain confined; L2 ∝ a(1 - e2) for semimajor axis a and eccentricity e. In a circular ring, L conservation demands that the ring quickly spread apart when some colliding particles lose energy while others gain it. By contrast, in an eccentric ring, energy loss and the associated decay of the average semi-major axes can be offset by a decrease in the average eccentricity. We argue that a ring's lifetime can be greatly extended if particles arrange themselves in this way (Borderies et al. 1984). The key difference of our model, however, is that rings need not be shepherded and can confine themselves provided they are sufficiently eccentric. Satellites merely extend the rings' lifespans by pumping up their eccentricities.This confinement mechanism can explain the existence and longevity of narrow ringlets in a variety of contexts. Saturn's Titan ringlet, which is quite circular, may nevertheless be able to confine itself indefinitely if its eccentricity decay is balanced by the increase from the resonance with Titan. Preliminary simulations presented by Rimlinger et al. at this year's DDA Conference have verified that this ring can self-confine even in the absence of any satellite; we update these findings with new results that include the effects of Titan. Furthermore, Mimas' resonance with the edge of the B ring may excite its higher order modes to similar effect. We update the findings of Hahn and Spitale (2013), who used artificial forces to confine the B ring's edge, and suggest that with a suitable viscosity and density, no such forces will be needed to keep the edge sharp. Finally, a ring that is "born" with a sufficiently high eccentricity may live for hundreds of millions or even billions of years in isolation if the rate of decay is slow enough. We present simulations exploring such a scenario.

Non-Linear Dynamics of Saturn's Rings

NASA Astrophysics Data System (ADS)

Esposito, L. W.

2016-12-01

Non-linear processes can explain why Saturn's rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. Stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, that push the system across thresholds that lead to persistent states. Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit, with relative velocity ranging from nearly zero to a multiple of the orbit average. Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like `straw' that can explain the halo morphology and spectroscopy: Cyclic velocity changes cause perturbed regions to reach higher collision speeds at some orbital phases, which preferentially removes small regolith particles; surrounding particles diffuse back too slowly to erase the effect: this gives the halo morphology; this requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km).Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing.Ring dynamics and history implications: Moon-triggered clumping explains both small and large particles at resonances. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating it as an asymmetric random walk with reflecting boundaries determines the power law index, using results of numerical simulations in the tidal environment. Aggregates can explain many dynamic aspects of the rings and can renew rings by shielding and recycling the material within them, depending on how long the mass is sequestered. We can ask: Are Saturn's rings a chaotic non-linear driven system?

Lead Optimization Studies on FimH Antagonists: Discovery of Potent and Orally Bioavailable Ortho-substituted Biphenyl Mannosides

PubMed Central

Han, Zhenfu; Pinkner, Jerome S.; Ford, Bradley; Chorell, Erik; Crowley, Jan M.; Cusumano, Corinne K.; Campbell, Scott; Henderson, Jeffrey P.; Hultgren, Scott J.; Janetka, James W.

2012-01-01

Herein, we describe the X-ray structure-based design and optimization of biaryl mannoside FimH inhibitors. Diverse modifications to the biaryl ring to improve drug-like physical and pharmacokinetic properties of mannosides were assessed for FimH binding affinity based on their effects on hemagglutination and biofilm formation along with direct FimH binding assays. Substitution on the mannoside phenyl ring ortho to the glycosidic bond results in large potency enhancements of several-fold higher than corresponding unsubstituted matched pairs and can be rationalized from increased hydrophobic interactions with the FimH hydrophobic ridge (Ile13) or “tyrosine gate” (Tyr137 and Tyr48) also lined by Ile52. The lead mannosides have increased metabolic stability and oral bioavailability as determined from in vitro PAMPA predictive model of cellular permeability and in vivo pharmacokinetic studies in mice, thereby representing advanced preclinical candidates with promising potential as novel therapeutics for the clinical treatment and prevention of recurring urinary tract infections. PMID:22449031

Highly linear ring modulator from hybrid silicon and lithium niobate.

PubMed

Chen, Li; Chen, Jiahong; Nagy, Jonathan; Reano, Ronald M

2015-05-18

We present a highly linear ring modulator from the bonding of ion-sliced x-cut lithium niobate onto a silicon ring resonator. The third order intermodulation distortion spurious free dynamic range is measured to be 98.1 dB Hz(2/3) and 87.6 dB Hz(2/3) at 1 GHz and 10 GHz, respectively. The linearity is comparable to a reference lithium niobate Mach-Zehnder interferometer modulator operating at quadrature and over an order of magnitude greater than silicon ring modulators based on plasma dispersion effect. Compact modulators for analog optical links that exploit the second order susceptibility of lithium niobate on the silicon platform are envisioned.

Increasing carbon discrimination rates and depth of water uptake favor the growth of Mediterranean evergreen trees in the ecotone with temperate deciduous forests.

PubMed

Barbeta, Adrià; Peñuelas, Josep

2017-12-01

Tree populations at the low-altitudinal or -latitudinal limits of species' distributional ranges are predicted to retreat toward higher altitudes and latitudes to track the ongoing changes in climate. Studies have focused on the climatic sensitivity of the retreating species, whereas little is known about the potential replacements. Competition between tree species in forest ecotones will likely be strongly influenced by the ecophysiological responses to heat and drought. We used tree-ring widths and δ 13 C and δ 18 O chronologies to compare the growth rates and long-term ecophysiological responses to climate in the temperate-Mediterranean ecotone formed by the deciduous Fagus sylvatica and the evergreen Quercus ilex at the low altitudinal and southern latitudinal limit of F. sylvatica (NE Iberian Peninsula). F. sylvatica growth rates were similar to those of other southern populations and were surprisingly not higher than those of Q. ilex, which were an order of magnitude higher than those in nearby drier sites. Higher Q. ilex growth rates were associated with high temperatures, which have increased carbon discrimination rates in the last 25 years. In contrast, stomatal regulation in F. sylvatica was proportional to the increase in atmospheric CO 2 . Tree-ring δ 18 O for both species were mostly correlated with δ 18 O in the source water. In contrast to many previous studies, relative humidity was not negatively correlated with tree-ring δ 18 O but had a positive effect on Q. ilex tree-ring δ 18 O. Furthermore, tree-ring δ 18 O decreased in Q. ilex over time. The sensitivity of Q. ilex to climate likely reflects the uptake of deep water that allowed it to benefit from the effect of CO 2 fertilization, in contrast to the water-limited F. sylvatica. Consequently, Q. ilex is a strong competitor at sites currently dominated by F. sylvatica and could be favored by increasingly warmer conditions. © 2017 John Wiley & Sons Ltd.

Comparative genomic analysis of the eight-membered ring cystine knot-containing bone morphogenetic protein antagonists.

PubMed

Avsian-Kretchmer, Orna; Hsueh, Aaron J W

2004-01-01

TGF-beta family proteins with a cystine knot motif serve as ligands for diverse families of plasma membrane receptors. Bone morphogenetic protein (BMP) antagonists represent a subgroup of these proteins, some of which bind BMPs and antagonize their actions during development and morphogenesis. Availability of completed genome sequences from diverse organisms allows bioinformatic analysis of the evolution of BMP antagonists and facilitates their classification. Using a regular expression algorithm (http://BioRegEx.stanford.edu), an exhaustive search of the human genome identified all cystine knot-containing BMP antagonists. Based on the size of the cystine ring, these proteins were divided into three subfamilies: CAN (eight-membered ring), twisted gastrulation (nine-membered ring), as well as chordin and noggin (10-membered ring). The CAN family can be divided further into four subgroups based on a conserved arrangement of additional cysteine residues-gremlin and PRDC, cerberus and coco, and DAN, together with USAG-1 and sclerostin. We searched for orthologs of human BMP antagonists in the genomes of model organisms and analyzed their phylogenetic relationship. New human paralogs were identified together with the verification of orthologous relationships of known genes. We also discuss the physiological roles of the CAN subfamily of BMP antagonists and the associated genetic defects. Based on the known three-dimensional structure of key cystine knot proteins, we postulated disulfide bondings for eight-membered ring BMP antagonists to predict their potential folding and dimerization.

Improvement of the performances of a tandem simulated moving bed chromatography by controlling the yield level of a key product of the first simulated moving bed unit.

PubMed

Mun, Sungyong; Wang, Nien-Hwa Linda

2017-03-10

One of the trustworthy processes for ternary separation is a tandem simulated moving bed (SMB) process, which consists of two subordinate four-zone SMB units (Ring I and Ring II). To take full advantage of a tandem SMB as a means of recovering all three products with high purities and high economical efficiency, it is important to understand how the separation condition in Ring II is affected by that in Ring I, and further to reflect such point in the stage of designing a tandem SMB. In regard to such issue, it was clarified in this study that the Ring I factors affecting the Ring II condition could be represented by the yield level of a key product of Ring I (Y key RingI ). As the Y key RingI level became higher, the amount of the Ring I key-product that was reloaded into Ring II was reduced, which affected favorably the Ring II separation condition. On the other hand, the higher Y key RingI level caused a larger dilution for the stream from Ring I to Ring II, which affected adversely the Ring II separation condition. As a result, a minimum in the desorbent usage of a tandem SMB occurred at the Y key RingI level where the two aforementioned factors could be balanced with each other. If such an optimal Y key RingI level was adopted, the desorbent usage could be reduced by up to 25%. It was also found that as the throughput of a tandem SMB became higher, the factor related to the migration of the Ring I key-product into Ring II was more influential in the performances of a tandem SMB than the factor related to the dilution of the stream from Ring I to Ring II. Copyright © 2016 Elsevier B.V. All rights reserved.

Ring Current Development During Storm Main Phase

NASA Technical Reports Server (NTRS)

Fok, Mei-Ching; Moore, Thomas E.; Greenspan, Marian E.

1996-01-01

The development of the ring current ions in the inner magnetosphere during the main phase of a magnetic storm is studied. The temporal and spatial evolution of the ion phase space densities in a dipole field are calculated using a three dimensional ring current model, considering charge exchange and Coulomb losses along drift paths. The simulation starts with a quiet time distribution. The model is tested by comparing calculated ion fluxes with Active Magnetospheric Particle Tracer Explorers/CCE measurement during the storm main phase on May 2, 1986. Most of the calculated omnidirectional fluxes are in good agreement with the data except on the dayside inner edge (L less than 2.5) of the ring current, where the ion fluxes are underestimated. The model also reproduces the measured pitch angle distributions of ions with energies below 10 keV. At higher energy, an additional diffusion in pitch angle is necessary in order to fit the data. The role of the induced electric field on the ring current dynamics is also examined by simulating a series of substorm activities represented by stretching and collapsing the magnetic field lines. In response to the impulsively changing fields, the calculated ion energy content fluctuates about a mean value that grows steadily with the enhanced quiescent field.

Lack of Spontaneous Sister Chromatid Exchanges in Somatic Cells of DROSOPHILA MELANOGASTER

PubMed Central

Gatti, M.; Santini, G.; Pimpinelli, S.; Olivieri, G.

1979-01-01

Neural ganglia of wild type third-instar larvae of Drosophila melanogaster were incubated for 13 hours at various concentrations of BUdR (1, 3, 9, 27 µg/ml). Metaphases were collected with colchicine, stained with Hoechst 33258, and scored under a fluorescence microscope. Metaphases in which the sister chromatids were clearly differentiated were scored for the presence of sister-chromatid exchanges (SCEs). At the lowest concentration of BUdR (1 µg/ml), no SCEs were observed in either male or female neuroblasts. The SCEs were found at the higher concentrations of BUdR (3, 9 and 27 µg/ml) and with a greater frequency in females than in males. Therefore SCEs are not a spontaneous phenomenon in D. melanogaster, but are induced by BUdR incorporated in the DNA. A striking nonrandomness was found in the distribution of SCEs along the chromosomes. More than a third of the SCEs were clustered in the junctions between euchromatin and heterochromatin. The remaining SCEs were preferentially localized within the heterochromatic regions of the X chromosome and the autosomes and primarily on the entirely heterochromatic Y chromosome.—In order to find an alternative way of measuring the frequency of SCEs in Drosophila neuroblasts, the occurrence of double dicentric rings was studied in two stocks carrying monocentric ring-X chromosomes. One ring chromosome, C(1)TR 94–2, shows a rate of dicentric ring formation corresponding to the frequency of SCEs observed in the BUdR-labelled rod chromosomes. The other ring studied, R(1)2, exhibits a frequency of SCEs higher than that observed with both C(1)TR 94–2 and rod chromosomes. PMID:109350

Ultrathin gold nanoribbons synthesized within the interior cavity of a self-assembled peptide nanoarchitecture.

PubMed

Tomizaki, Kin-ya; Wakizaka, Shota; Yamaguchi, Yuichi; Kobayashi, Akitsugu; Imai, Takahito

2014-01-28

There is increasing interest in gold nanocrystals due to their unique physical, chemical, and biocompatible properties. In order to develop a template-assisted method for the fabrication of gold nanocrystals, we demonstrate here the de novo design and synthesis of a β-sheet-forming nonapeptide (RU006: Ac-AIAKAXKIA-NH2, X = L-2-naphthylalanine) which undergoes self-assembly to form disk-like nanoarchitectures approximately 100 nm wide and 2.5 nm high. These self-assemblies tend to form a network of higher-order assemblies in ultrapure water. Using RU006 as a template molecule, we fabricated ultrathin gold nanoribbons 50-100 nm wide, 2.5 nm high, and micrometers long without external reductants. Furthermore, in order to determine the mechanism of ultrathin gold nanoribbon formation, we synthesized four different RU006 analogues. On the basis of the results obtained using RU006 and these analogues, we propose the following mechanism for the self-assembly of RU006. First, RU006 forms a network by the cooperative association of disk-like assemblies in the presence of AuCl4(-) ions that are encapsulated and concentrated within the interior cavity of the network architectures. This is followed by electron transfer from the naphthalene rings to Au(III), resulting in slow growth to form ultrathin gold nanoribbons along the template network architectures under ambient conditions. The resulting ribbons retain the dimensions of the cavity of the template architecture. Our approach will allow the construction of diverse template architectural morphologies and will find applications in the construction of a variety of metallic nanoarchitectures.

Light and/or atomic beams to detect ultraweak gravitational effects

NASA Astrophysics Data System (ADS)

Tartaglia, Angelo; Belfi, Jacopo; Beverini, Nicolò; Di Virgilio, Angela; Ortolan, Antonello; Porzio, Alberto; Ruggiero, Matteo Luca

2014-06-01

We shall review the opportunities lent by ring lasers and atomic beams interferometry in order to reveal gravitomagnetic effects on Earth. Both techniques are based on the asymmetric propagation of waves in the gravitational field of a rotating mass; actually the times of flight for co- or counter-rotating closed paths turn out to be different. After discussing properties and limitations of the two approaches we shall describe the proposed GINGER experiment which is being developed for the Gran Sasso National Laboratories in Italy. The experimental apparatus will consist of a three-dimensional array of square rings, 6m × 6m, that is planned to reach a sensitivity in the order of 1prad/√Hertz or better. This sensitivity would be one order of magnitude better than the best existing ring, which is the G-ring in Wettzell, Bavaria, and would allow for the terrestrial detection of the Lense-Thirring effect and possibly of deviations from General Relativity. The possibility of using either the ring laser approach or atomic interferometry in a space mission will also be considered. The technology problems are under experimental study using both the German G-ring and the smaller G-Pisa ring, located at the Gran Sasso.

Circular Permutation of a Chaperonin Protein: Biophysics and Application to Nanotechnology

NASA Technical Reports Server (NTRS)

Paavola, Chad; Chan, Suzanne; Li, Yi-Fen; McMillan, R. Andrew; Trent, Jonathan

2004-01-01

We have designed five circular permutants of a chaperonin protein derived from the hyperthermophilic organism Sulfolobus shibatae. These permuted proteins were expressed in E. coli and are well-folded. Furthermore, all the permutants assemble into 18-mer double rings of the same form as the wild-type protein. We characterized the thermodynamics of folding for each permutant by both guanidine denaturation and differential scanning calorimetry. We also examined the assembly of chaperonin rings into higher order structures that may be used as nanoscale templates. The results show that circular permutation can be used to tune the thermodynamic properties of a protein template as well as facilitating the fusion of peptides, binding proteins or enzymes onto nanostructured templates.

Temperature Variations of Saturn Rings with Viewing Geometries from Prime to Equinox Cassini Missions

NASA Technical Reports Server (NTRS)

Deau, E. A.; Spilker, L. J.; Morishima, R.; Brooks, S.; Pilorz, S.; Altobelli, N.

2011-01-01

After more than six years in orbit around Saturn, the Cassini Composite Infrared Spectrometer (CIRS) has acquired an extensive set of measurements of Saturn's main rings (A, B, C and Cassini Division) in the thermal infrared. Temperatures were retrieved for the lit and unlit rings over a variety of ring geometries that include phase angle, solar and spacecraft elevations and local time. We show that some of these parameters (solar and spacecraft elevations, phase angle) play a role in the temperature variations in the first order, while the others (ring and particle local time) produced second order effects. The results of this comparison will be presented.

A source array for generating higher order acoustic modes in circular ducts

NASA Technical Reports Server (NTRS)

Wyerman, B. R.; Reethof, G.

1976-01-01

A unique source array has been developed for the generation of both spinning and non-spinning higher order modes in a circular duct. The array consists of two concentric rings of sources. Through individual control of the response of each element, the array provided phase and amplitude control in the radial as well as circumferential directions. Radial modes shapes were measured in a 12-inch diameter anechoically-terminated hollow duct. These modes could be generated at their cut-off frequency and throughout a frequency range extending to the cut-off frequency for the next higher order radial mode. Comparisons are given between theory and experiment for the generation of specific modes. The radial dependence of the measured mode shapes was enhanced considerably by the design of this array. The results indicate a significant improvement over previous mode generation mechanisms. The contamination of the generated mode by additional spurious modes is also considered for variations between individual elements within the source array.

The longitudinal offset technique for apodization of coupled resonator optical waveguide devices: concept and fabrication tolerance analysis.

PubMed

Doménech, José David; Muñoz, Pascual; Capmany, José

2009-11-09

In this paper, a novel technique to set the coupling constant between cells of a coupled resonator optical waveguide (CROW) device, in order to tailor the filter response, is presented. The technique is demonstrated by simulation assuming a racetrack ring resonator geometry. It consists on changing the effective length of the coupling section by applying a longitudinal offset between the resonators. On the contrary, the conventional techniques are based in the transversal change of the distance between the ring resonators, in steps that are commonly below the current fabrication resolution step (nm scale), leading to strong restrictions in the designs. The proposed longitudinal offset technique allows a more precise control of the coupling and presents an increased robustness against the fabrication limitations, since the needed resolution step is two orders of magnitude higher. Both techniques are compared in terms of the transmission esponse of CROW devices, under finite fabrication resolution steps.

Guiding and amplification properties of rod-type photonic crystal fibers with sectioned core doping

NASA Astrophysics Data System (ADS)

Selleri, S.; Poli, F.; Passaro, D.; Cucinotta, A.; Lægsgaard, J.; Broeng, J.

2009-05-01

Rod-type photonic crystal fibers are large mode area double-cladding fibers with an outer diameter of few millimeters which can provide important advantages for high-power lasers and amplifiers. Numerical studies have recently demonstrated the guidance of higher-order modes in these fibers, which can worsen the output beam quality of lasers and amplifiers. In the present analysis a sectioned core doping has been proposed for Ybdoped rod-type photonic crystal fibers, with the aim to improve the higher-order mode suppression. A full-vector modal solver based on the finite element method has been applied to properly design the low refractive index ring in the fiber core, which can provide an increase of the differential overlap between the fundamental and the higher-order mode. Then, the gain competition among the guided modes along the Yb-doped rod-type fibers has been investigated with a spatial and spectral amplifier model. Simulation results have shown the effectiveness of the sectioned core doping in worsening the higher-order mode overlap on the doped area, thus providing an effective single-mode behavior of the Yb-doped rod-type photonic crystal fibers.

"Ring rain" on Saturn's ionosphere: densities and temperatures from 2011 observations and re-detection in 2013 observations

NASA Astrophysics Data System (ADS)

O'Donoghue, J.; Moore, L.; Melin, H.; Connerney, J. E. P.; Oliversen, R. J.

2017-12-01

In ground-based observations using the 10 meter W. M. Keck telescope in 2011, we discovered that the "ring rain" which falls on Saturn from the rings (along magnetic field lines) leaves an imprint on the upper-atmospheric H3+ ion. H3+ emissions were brightest where water products are expected to fall. Through subsequent modeling of the upper atmosphere, it became clear that an influx of water products (e.g. H2O+, O+, etc.) would act to soak up electrons - something that would otherwise destroy H3+ through recombination - and lead to a higher H3+ density and therefore emission. Here we present the first re-detections of the imprint of "ring rain" on Saturn's ionospheric H3+ from ground-based Keck telescope data from 2013. Observed intensities at low-latitudes decreased by an order of magnitude from 2011 to 2013, likely due to a decrease in upper atmospheric temperature by 100 K. A new analysis of 2011 observations revealed temperatures and densities as a function of latitude on Saturn for the first time. Where water influx is expected, H3+ column densities are high (as models predicted) and temperatures are low. While the latter was unexpected, the effect of ring rain on electron densities is stronger at lower altitudes. Therefore, as ring rain enhances density at lower altitudes where the temperature is lower, it should result in the emitting column of H3+ having a lower average temperature. These results come at a critical time as the Cassini spacecraft completes all orbits between planet and rings, with the opportunity to sample the forces and material fluxes related to ring rain.

VizieR Online Data Catalog: Circumnuclear star-forming regions (Alvarez-Alvarez+, 2015)

NASA Astrophysics Data System (ADS)

Alvarez-Alvarez, M.; Diaz, A. I.; Terlevich, E.; Terlevich, R.

2016-01-01

In order to achieve our scientific goals, we have studied a diverse population of galaxies with reported circumnuclear rings of SFRs in the bibliography. The data were acquired during five observing runs. For the first two runs (from 1988 to 1990), we used a blue sensitive GEC CCD at the f/15 Cassegrain focus of the 1.0m. Jacobus Kaptein Telescope of the Isaac Newton Group at the Observatorio del Roque de los Muchachos, La Palma, Spain. The CCD had 578x385 pixels 22um wide. The last three observing runs were carried on from 1999 to 2000 at the Centro Astronomico Hispano Aleman de Calar Alto, Almeria, Spain. (3 data files).

Reagent-based DOS: developing a diastereoselective methodology to access spirocyclic- and fused heterocyclic ring systems.

PubMed

Damerla, V Surendra Babu; Tulluri, Chiranjeevi; Gundla, Rambabu; Naviri, Lava; Adepally, Uma; Iyer, Pravin S; Murthy, Y L N; Prabhakar, Nampally; Sen, Subhabrata

2012-10-01

Herein, we report a diversity-oriented-synthesis (DOS) approach for the synthesis of biologically relevant molecular scaffolds. Our methodology enables the facile synthesis of fused N-heterocycles, spirooxoindolones, tetrahydroquinolines, and fused N-heterocycles. The two-step sequence starts with a chiral-bicyclic-lactam-directed enolate-addition/substitution step. This step is followed by a ring-closure onto the built-in scaffold electrophile, thereby leading to stereoselective carbocycle- and spirocycle-formation. We used in silico tools to calibrate our compounds with respect to chemical diversity and selected drug-like properties. We evaluated the biological significance of our scaffolds by screening them in two cancer cell-lines. In summary, our DOS methodology affords new, diverse scaffolds, thereby resulting in compounds that may have significance in medicinal chemistry. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly linear dual ring resonator modulator for wide bandwidth microwave photonic links.

PubMed

Hosseinzadeh, Arash; Middlebrook, Christopher T

2016-11-28

A highly linear dual ring resonator modulator (DRRM) design is demonstrated to provide high spur-free dynamic range (SFDR) in a wide operational bandwidth. Harmonic and intermodulation distortions are theoretically analyzed in a single ring resonator modulator (RRM) with Lorentzian-shape transfer function and a strategy is proposed to enhance modulator linearity for wide bandwidth applications by utilizing DRRM. Third order intermodulation distortion is suppressed in a frequency independent process with proper splitting ratio of optical and RF power and proper dc biasing of the ring resonators. Operational bandwidth limits of the DRRM are compared to the RRM showing the capability of the DRRM in providing higher SFDR in an unlimited operational bandwidth. DRRM bandwidth limitations are a result of the modulation index from each RRM and their resonance characteristics that limit the gain and noise figure of the microwave photonic link. The impact of the modulator on microwave photonic link figure of merits is analyzed and compared to RRM and Mach-Zehnder Interference (MZI) modulators. Considering ± 5 GHz operational bandwidth around the resonance frequency imposed by the modulation index requirement the DRRM is capable of a ~15 dB SFDR improvement (1 Hz instantaneous bandwidth) versus RRM and MZI.

DFT study on the adsorption behavior and electronic response of AlN nanotube and nanocage toward toxic halothane gas

NASA Astrophysics Data System (ADS)

Mohammadi, R.; Hosseinian, A.; Khosroshahi, E. Saedi; Edjlali, L.; Vessally, E.

2018-04-01

We have investigated the adsorption of a halothane molecule on the AlN nanotube, and nanocage using density functional theory calculations. We predicted that the halothane molecule tends to be physically adsorbed on the surface of AlN nanotube with adsorption energy (Ead) of -4.2 kcal/mol. The electronic properties of AlN nanotube are not affected by the halothane, and it is not a sensor. But the AlN nanocage is more reactive than the AlN nanotube because of its higher curvature. The halothane tends to be adsorbed on a hexagonal ring, an Alsbnd N bond, and a tetragonal ring of the AlN nanocage. The adsorption ability order is as follows: tetragonal ring (Ead = -14.7 kcal/mol) > Alsbnd N bond (Ead = -12.3 kcal/mol) > hexagonal ring (Ead = -10.1 kcal/mol). When a halothane molecule is adsorbed on the AlN nanocage, its electrical conductivity is increased, demonstrating that it can yield an electronic signal at the presence of this molecule, and can be employed in chemical sensors. The AlN nanocage benefits from a short recovery time of about 58 ms at room temperature.

Photophysical Characterization and BSA Interaction of Direct Ring Carboxy Functionalized Symmetrical squaraine Dyes

NASA Astrophysics Data System (ADS)

Saikiran, Maryala; Pandey, Shyam S.; Hayase, Shuzi; Kato, Tamaki

2017-11-01

A series of far-red sensitive symmetrical squaraine dyes bearing direct -COOH functionalized indole ring were synthesized, characterized and subjected to photophysical investigations. These symmetrical squaraine dyes were then subjected to investigate their interaction with bovine serum albumin (BSA) in Phosphate buffer solutions. All the squaraine dyes under investigation exhibit intense and sharp optical absorption mainly in the far-red wavelength region from 550 nm -700 nm having very high molar extinction coefficients from 1.3 × 105 dm3.mol-1.cm-1. A very small Stokes shift of 10-17 nm indicates the rigid conformational structure of squaraine chromophore. Interaction of these dyes with BSA leads to not only enhanced emission intensity but also bathochromically shifted absorption maximum due to formation of dye-BSA conjugate. These dyes bind strongly with BSA having about an order of magnitude higher binding constant as compared to the reported squaraine dyes. Amongst the symmetrical squaraine dyes investigated in this work one bearing substituents like trifluorobutyl as alkyl chain at N-position of indole ring and carboxylic acid on benzene ring at the terminal (SQ-26) exhibited highest association with the BSA having very high binding constant 8.01 × 106 M-1.

[Dendroclimatic potentials for the tree rings of Huangshan pine (Pinus taiwanensis ) at Xiaolinhai in the western Dabie Mountains, China].

PubMed

Peng, Jian-Feng; Li, Guo-Dong; Li, Ling-Ling

2014-07-01

By using the dendrochronology research methods, this paper developed the 1915-2011 tree ring-width standard chronology of the Huangshan pine (Pinus taiwanesis) at the north slope of western Dabie Mountains in the junction of Hubei, Henan and Anhui provinces. High mean sensitivity (MS) indicated that there was conspicuous high-frequency climate signals and high first-order autocorrelation (AC) showed there were significant lag-effects of tree previous growth. The higher signal-to-noise ratio (SNR) and expressed population signal (EPS) indicated that the trees had high levels of common climate signals. Correlations between the tree ring-width standard chronology and climatic factors (1959-2011) revealed the significant influences of temperature, precipitation and relative humidity on the tree width growth of Huangshan pine by the end of growing season (September and October). Significant positive correlations were found between the tree-ring indices and the Palmer drought severity index (PDSI) of current September and October. In conclusion, the combination of water and heat of September and October is the major effect factor for the growth of Huangshan pine in western Dabie Mountains.

Integration and initial operation of the multi-component large ring laser structure ROMY

NASA Astrophysics Data System (ADS)

Schreiber, Karl Ulrich; Igel, Heiner; Wassermann, Joachim; Gebauer, André; Simonelli, Andrea; Bernauer, Felix; Donner, Stefanie; Hadziioannou, Celine; Egdorf, Sven; Wells, Jon-Paul

2017-04-01

Rotation sensing for the geosciences requires a high sensor resolution of the order of 10 pico- radians per second or even less. An optical Sagnac interferometer offers this sensitivity, provided that the scale factor can be made very large. We have designed and built a multi- component ring laser system, consisting of 4 individual large ring lasers, each covering an area of more than 62 square m. The rings are orientated in the shape of a tetrahedron, so that all 3 spatial directions are covered, allowing also for some redundancy. We report on the initial operation of the free running gyroscopes in their underground facility in order to establish a performance estimate for the ROMY ring laser structure. Preliminary results suggest that the quantum noise limit is lower than that of the G ring laser.

High-molecular-weight tropomyosins localize to the contractile rings of dividing CNS cells but are absent from malignant pediatric and adult CNS tumors.

PubMed

Hughes, Julie A I; Cooke-Yarborough, Claire M; Chadwick, Nigel C; Schevzov, Galina; Arbuckle, Susan M; Gunning, Peter; Weinberger, Ron P

2003-04-01

Tropomyosin has been implicated in the control of actin filament dynamics during cell migration, morphogenesis, and cytokinesis. In order to gain insight into the role of tropomyosins in cell division, we examined their expression in developing and neoplastic brain tissue. We found that the high-molecular-weight tropomyosins are downregulated at birth, which correlates with glial cell differentiation and withdrawal of most cells from the cell cycle. Expression of these isoforms was restricted to proliferative areas in the embryonic brain and was absent from the adult, where the majority of cells are quiescent. However, they were induced under conditions where glial cells became proliferative in response to injury. During cytokinesis, these tropomyosin isoforms were associated with the contractile ring. We also investigated tropomyosin expression in neoplastic CNS tissues. Low-grade astrocytic tumors expressed high-molecular-weight tropomyosins, while highly malignant CNS tumors of diverse origin did not (P

Swelling of two-dimensional polymer rings by trapped particles.

PubMed

Haleva, E; Diamant, H

2006-09-01

The mean area of a two-dimensional Gaussian ring of N monomers is known to diverge when the ring is subject to a critical pressure differential, p c ~ N -1. In a recent publication (Eur. Phys. J. E 19, 461 (2006)) we have shown that for an inextensible freely jointed ring this divergence turns into a second-order transition from a crumpled state, where the mean area scales as [A]~N-1, to a smooth state with [A]~N(2). In the current work we extend these two models to the case where the swelling of the ring is caused by trapped ideal-gas particles. The Gaussian model is solved exactly, and the freely jointed one is treated using a Flory argument, mean-field theory, and Monte Carlo simulations. For a fixed number Q of trapped particles the criticality disappears in both models through an unusual mechanism, arising from the absence of an area constraint. In the Gaussian case the ring swells to such a mean area, [A]~ NQ, that the pressure exerted by the particles is at p c for any Q. In the freely jointed model the mean area is such that the particle pressure is always higher than p c, and [A] consequently follows a single scaling law, [A]~N(2) f (Q/N), for any Q. By contrast, when the particles are in contact with a reservoir of fixed chemical potential, the criticality is retained. Thus, the two ensembles are manifestly inequivalent in these systems.

Crosslinking of SAVY-4000 O-rings as a Function of Aging Conditions

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

Van Buskirk, Caleb Griffith

SAVY-4000 containers were developed as a part of DOE M 441.1-1 to protect workers who handle stored nuclear material from exposure due to loss of containment.1 The SAVY-4000 is comprised of three parts: a lid, a container, and a cross-linked fluoropolymer O-ring. Degradation of the O-ring during use could limit the lifetime of the SAVY-4000. In order to quantify the chemical changes of the Oring over time, the molecular weight between crosslinks was determined as a function of aging conditions using a swelling technique. Because the O-ring is a cross-linked polymer, it will absorb solvent into its matrix without dissolving.more » The relative amount of solvent uptake can be related to the degree of crosslinking using an equation developed by Paul Flory and John Rehner Jr3. This method was used to analyze O-ring samples aged under thermal and ionizing-radiation conditions. It was found that at the harsher thermal gaining conditions in absence of ionizing-radiation the average molecular weight between crosslinks decreased, indicating a rise in crosslinks, which may be attributable to advanced aging with no ionizing radiation present. Inversely, in the presence of ionizing radiation it was found that material has a higher level of cross-linking with age. This information could be used to help predict the lifetime of the O-rings in SAVY-4000 containers under service conditions.« less

Simulations of phase space distributions of storm time proton ring current

NASA Technical Reports Server (NTRS)

Chen, Margaret W.; Lyons, Larry R.; Schulz, Michael

1994-01-01

We use results of guiding-center simulations of ion transport to map phase space densities of the stormtime proton ring current. We model a storm as a sequence of substorm-associated enhancements in the convection electric field. Our pre-storm phase space distribution is an analytical solution to a steady-state transport model in which quiet-time radial diffusion balances charge exchange. This pre-storm phase space spectra at L approximately 2 to 4 reproduce many of the features found in observed quiet-time spectra. Using results from simulations of ion transport during model storms having main phases of 3, 6, and 12 hr, we map phase space distributions from the pre-storm distribution in accordance with Liouville's theorem. We find stormtime enhancements in the phase space densities at energies E approximately 30-160 keV for L approximately 2.5 to 4. These enhancements agree well with the observed stormtime ring current. For storms with shorter main phases (approximately 3 hr), the enhancements are caused mainly by the trapping of ions injected from open night side trajectories, and diffusive transport of higher-energy (greater than or approximately 160 keV) ions contributes little to the stormtime ring current. However, the stormtime ring current is augmented also by the diffusive transport of higher-energy ions (E greater than or approximately 160 keV) durinng stroms having longer main phases (greater than or approximately 6 hr). In order to account for the increase in Dst associated with the formation of the stormtime ring current, we estimate the enhancement in particle-energy content that results from stormtime ion transport in the equatorial magnetosphere. We find that transport alone cannot account for the entire increase in absolute value of Dst typical of a major storm. However, we can account for the entire increase in absolute value of Dst by realistically increasing the stormtime outer boundary value of the phase space density relative to the quiet-time value. We compute the magnetic field produced by the ring current itself and find that radial profiles of the magnetic field depression resemble those obtained from observational data.

Type II GaSb quantum ring solar cells under concentrated sunlight.

PubMed

Tsai, Che-Pin; Hsu, Shun-Chieh; Lin, Shih-Yen; Chang, Ching-Wen; Tu, Li-Wei; Chen, Kun-Cheng; Lay, Tsong-Sheng; Lin, Chien-chung

2014-03-10

A type II GaSb quantum ring solar cell is fabricated and measured under the concentrated sunlight. The external quantum efficiency confirms the extended absorption from the quantum rings at long wavelength coinciding with the photoluminescence results. The short-circuit current of the quantum ring devices is 5.1% to 9.9% more than the GaAs reference's under various concentrations. While the quantum ring solar cell does not exceed its GaAs counterpart in efficiency under one-sun, the recovery of the open-circuit voltages at higher concentration helps to reverse the situation. A slightly higher efficiency (10.31% vs. 10.29%) is reported for the quantum ring device against the GaAs one.

A dual-band reconfigurable Yagi-Uda antenna with diverse radiation patterns

NASA Astrophysics Data System (ADS)

Saurav, Kushmanda; Sarkar, Debdeep; Srivastava, Kumar Vaibhav

2017-07-01

In this paper, a dual-band pattern reconfigurable antenna is proposed. The antenna comprises of a dual-band complementary split ring resonators (CSRRs) loaded dipole as the driven element and two copper strips with varying lengths as parasitic segments on both sides of the driven dipole. PIN diodes are used with the parasitic elements to control their electrical length. The CSRRs loading provide a lower order mode in addition to the reference dipole mode, while the parasitic elements along with the PIN diodes are capable of switching the omni-directional radiation of the dual-band driven element to nine different configurations of radiation patterns which include bi-directional end-fire, broadside, and uni-directional end-fire in both the operating bands. A prototype of the designed antenna together with the PIN diodes and DC bias lines is fabricated to validate the concept of dual-band radiation pattern diversity. The simulation and measurement results are in good agreement. The proposed antenna can be used in wireless access points for PCS and WLAN applications.

The dendroanalysis of oak trees as a method of biomonitoring past and recent contamination in an area influenced by uranium mining.

PubMed

Märten, Arno; Berger, Dietrich; Köhler, Mirko; Merten, Dirk

2015-12-01

We reconstructed the contamination history of an area influenced by 40 years of uranium mining and subsequent remediation actions using dendroanalysis (i.e., the determination of the elemental content of tree rings). The uranium content in the tree rings of four individual oak trees (Quercus sp.) was determined by laser ablation with inductively coupled plasma mass spectrometry (LA-ICP-MS). This technique allows the investigation of trace metals in solid samples with a spatial resolution of 250 μm and a detection limit below 0.01 μg/g for uranium. The investigations show that in three of the four oaks sampled, there were temporally similar uranium concentrations. These were approximately 2 orders of magnitude higher (0.15 to 0.4 μg/g) than those from before the period of active mining (concentrations below 0.01 μg/g). After the mining was terminated and the area was restored, the uranium contents in the wood decreased by approximately 1 order of magnitude. The similar radial uranium distribution patterns of the three trees were confirmed by correlation analysis. In combination with the results of soil analyses, it was determined that there was a heterogeneous contamination in the forest investigated. This could be confirmed by pre-remediation soil uranium contents from literature. The uranium contents in the tree rings of the oaks investigated reflect the contamination history of the study area. This study demonstrates that the dendrochemical analysis of oak tree rings is a suitable technique for investigating past and recent uranium contamination in mining areas.

Ocean plankton. Environmental characteristics of Agulhas rings affect interocean plankton transport.

PubMed

Villar, Emilie; Farrant, Gregory K; Follows, Michael; Garczarek, Laurence; Speich, Sabrina; Audic, Stéphane; Bittner, Lucie; Blanke, Bruno; Brum, Jennifer R; Brunet, Christophe; Casotti, Raffaella; Chase, Alison; Dolan, John R; d'Ortenzio, Fabrizio; Gattuso, Jean-Pierre; Grima, Nicolas; Guidi, Lionel; Hill, Christopher N; Jahn, Oliver; Jamet, Jean-Louis; Le Goff, Hervé; Lepoivre, Cyrille; Malviya, Shruti; Pelletier, Eric; Romagnan, Jean-Baptiste; Roux, Simon; Santini, Sébastien; Scalco, Eleonora; Schwenck, Sarah M; Tanaka, Atsuko; Testor, Pierre; Vannier, Thomas; Vincent, Flora; Zingone, Adriana; Dimier, Céline; Picheral, Marc; Searson, Sarah; Kandels-Lewis, Stefanie; Acinas, Silvia G; Bork, Peer; Boss, Emmanuel; de Vargas, Colomban; Gorsky, Gabriel; Ogata, Hiroyuki; Pesant, Stéphane; Sullivan, Matthew B; Sunagawa, Shinichi; Wincker, Patrick; Karsenti, Eric; Bowler, Chris; Not, Fabrice; Hingamp, Pascal; Iudicone, Daniele

2015-05-22

Agulhas rings provide the principal route for ocean waters to circulate from the Indo-Pacific to the Atlantic basin. Their influence on global ocean circulation is well known, but their role in plankton transport is largely unexplored. We show that, although the coarse taxonomic structure of plankton communities is continuous across the Agulhas choke point, South Atlantic plankton diversity is altered compared with Indian Ocean source populations. Modeling and in situ sampling of a young Agulhas ring indicate that strong vertical mixing drives complex nitrogen cycling, shaping community metabolism and biogeochemical signatures as the ring and associated plankton transit westward. The peculiar local environment inside Agulhas rings may provide a selective mechanism contributing to the limited dispersal of Indian Ocean plankton populations into the Atlantic. Copyright © 2015, American Association for the Advancement of Science.

Diversity-oriented synthesis leads to an effective class of bifunctional linchpins uniting anion relay chemistry (ARC) with benzyne reactivity

PubMed Central

Smith, Amos B.; Kim, Won-Suk

2011-01-01

In conjunction with the construction of a diversity-oriented synthesis library of 10-membered ring “natural product-like” macrolides, the design, synthesis, and validation of a unique class of bifunctional linchpins, uniting benzyne reactivity initiated by type II anion relay chemistry (ARC) has been achieved, permitting access to diverse [2+2], [3+2], and [4+2] cycloadducts. PMID:21245309

Circuit variability interacts with excitatory-inhibitory diversity of interneurons to regulate network encoding capacity.

PubMed

Tsai, Kuo-Ting; Hu, Chin-Kun; Li, Kuan-Wei; Hwang, Wen-Liang; Chou, Ya-Hui

2018-05-23

Local interneurons (LNs) in the Drosophila olfactory system exhibit neuronal diversity and variability, yet it is still unknown how these features impact information encoding capacity and reliability in a complex LN network. We employed two strategies to construct a diverse excitatory-inhibitory neural network beginning with a ring network structure and then introduced distinct types of inhibitory interneurons and circuit variability to the simulated network. The continuity of activity within the node ensemble (oscillation pattern) was used as a readout to describe the temporal dynamics of network activity. We found that inhibitory interneurons enhance the encoding capacity by protecting the network from extremely short activation periods when the network wiring complexity is very high. In addition, distinct types of interneurons have differential effects on encoding capacity and reliability. Circuit variability may enhance the encoding reliability, with or without compromising encoding capacity. Therefore, we have described how circuit variability of interneurons may interact with excitatory-inhibitory diversity to enhance the encoding capacity and distinguishability of neural networks. In this work, we evaluate the effects of different types and degrees of connection diversity on a ring model, which may simulate interneuron networks in the Drosophila olfactory system or other biological systems.

DNA barcodes and citizen science provoke a diversity reappraisal for the "ring" butterflies of Peninsular Malaysia (Ypthima: Satyrinae: Nymphalidae: Lepidoptera).

PubMed

Jisming-See, Shi-Wei; Sing, Kong-Wah; Wilson, John-James

2016-10-01

The "rings" belonging to the genus Ypthima are amongst the most common butterflies in Peninsular Malaysia. However, the species can be difficult to tell apart, with keys relying on minor and often non-discrete ring characters found on the hindwing. Seven species have been reported from Peninsular Malaysia, but this is thought to be an underestimate of diversity. DNA barcodes of 165 individuals, and wing and genital morphology, were examined to reappraise species diversity of this genus in Peninsular Malaysia. DNA barcodes collected during citizen science projects-School Butterfly Project and Peninsular Malaysia Butterfly Count-recently conducted in Peninsular Malaysia were included. The new DNA barcodes formed six groups with different Barcode Index Numbers (BINs) representing four species reported in Peninsular Malaysia. When combined with public DNA barcodes from the Barcode Of Life Datasystems, several taxonomic issues arose. We consider the taxon Y. newboldi, formerly treated as a subspecies of Y. baldus, as a distinct species. DNA barcodes also supported an earlier suggestion that Y. nebulosa is a synonym under Y. horsfieldii humei. Two BINs of the genus Ypthima comprising DNA barcodes collected during citizen science projects did not correspond to any species previously reported in Peninsular Malaysia.

Using Tree-Ring Data, Research, and Expeditions as an Accessible, Hands-on "Bridge" into Climate Studies for Diverse Audiences

NASA Astrophysics Data System (ADS)

Davi, N. K.; Wattenberg, F.; Pringle, P. T.; Tanenbaum, J.; O'Brien, A.; Greidanus, I.; Perry, M.

2012-12-01

Tree-ring research provides an engaging, intuitive, and relevant entryway into understanding both climate-change and environmental research, as well as the process of science from inspiration, to fieldwork, to analysis, to publishing and communicating. The basic premise of dendrochronology is that annual rings reflect environmental conditions year-by-year and that by studying long-lived trees we can learn about past environments and climates for hundreds-to-thousands of years in the past. Conceptually, this makes tree-ring studies accessible to students and faculty for a number of reasons. First, in order to collect their data, dendrochronologists often launch expeditions to stunningly picturesque and remote places in search of long-lived, climate sensitive trees. Scientist exciting stories and images from the field can be leveraged to connect students to the study and the data. Second, tree-rings can be more easily explained as a proxy for climate than other methods (ice cores, carbon-isotope ratios, etc.), and most people have prior-knowledge about trees and annual growth rings. It is even possible, for example, for non-expert audiences to see climate variability through time with the naked eye by looking at climate sensitive tree cores. Third, tree-rings are interdisciplinary and illustrate the interplay between the mathematical sciences, the biological sciences, and the geosciences—that is, they show that the biosphere is a fundamental component of the Earth system. Here, we will present several projects have been initiated for a range of audiences, including; elementary school, where 5th graders visited a local forest to collect samples and apply their samples and what they learned to math and science classes. 5th grade students also leaned how to use Climate Explorer (KNMI), an online tool that allows scientist and students the opportunity to access and visualize global climate data within a few clicks. Geared to 2 and 4 year colleges, we are also collaboratively developing new interdisciplinary science and mathematical curriculum, interactive game modules, and multi-media that focus on using tree-ring expeditions and research projects that have real-world applications related to societal concerns (drought, warming, or in some cases, finances) to support student-centered inquiry-based learning. We are also creating professional development guides for teachers.

Current-induced SQUID behavior of superconducting Nb nano-rings

NASA Astrophysics Data System (ADS)

Sharon, Omri J.; Shaulov, Avner; Berger, Jorge; Sharoni, Amos; Yeshurun, Yosef

2016-06-01

The critical temperature in a superconducting ring changes periodically with the magnetic flux threading it, giving rise to the well-known Little-Parks magnetoresistance oscillations. Periodic changes of the critical current in a superconducting quantum interference device (SQUID), consisting of two Josephson junctions in a ring, lead to a different type of magnetoresistance oscillations utilized in detecting extremely small changes in magnetic fields. Here we demonstrate current-induced switching between Little-Parks and SQUID magnetoresistance oscillations in a superconducting nano-ring without Josephson junctions. Our measurements in Nb nano-rings show that as the bias current increases, the parabolic Little-Parks magnetoresistance oscillations become sinusoidal and eventually transform into oscillations typical of a SQUID. We associate this phenomenon with the flux-induced non-uniformity of the order parameter along a superconducting nano-ring, arising from the superconducting leads (‘arms’) attached to it. Current enhanced phase slip rates at the points with minimal order parameter create effective Josephson junctions in the ring, switching it into a SQUID.

Variation in soil macro-fauna diversity in seven humus orders of a Parrotio-Carpinetum forest association on Chromic Cambisols of Shast-klateh area in Iran

NASA Astrophysics Data System (ADS)

Izadi, M.; Habashi, H.; Waez-Mousavi, S. M.

2017-03-01

Soil biodiversity includes organisms which spend a part or all of their life cycle on or in the soil. Among soil-dwelling animals, macro-fauna as an important group of animals have important effects on the dynamics of soil organic matter and litter decomposition process. The humus forms interact with the climatic conditions, flora, as well as soil fauna, and microbial activity. In new humus form classifications, soil organisms play an important role in separation of humus horizons from one another. The subject of this study was to determine the diversity of macro fauna for different humus forms. We determined humus forms using morphological classification, and then 69 random samples were taken from plots of 100 cm2 in area, and soil macro-fauna species were collected by hand sorting method. Two classes of humus forms, including Mull (with three humus orders, namely Dysmull, Oligomull, and Mesomull,) and Amphi (with four humus orders, namely Leptoamphi, Eumacroamphi, Eumesoamphi, and Pachyamphi) were identified. A number of 13 macro-fauna orders were identified using identification key. Among the humus orders, Shannon diversity, Simpson evenness and Margalef richness indices were the highest in Pachyamphi order. Arthropod diversity in Pachyamphi humus order was higher than those of Mull. These results showed that diversity of soil macrofauna increase by increasing the thickness of the organic horizons (OL, OF, OH), especially OH horizon.

A FODO racetrack ring for nuSTORM: design and optimization

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

Liu, A.; Bross, A.; Neuffer, D.

2017-07-01

The goal of nuSTORM is to provide well-defined neutrino beams for precise measurements of neutrino cross-sections and oscillations. The nuSTORM decay ring is a compact racetrack storage ring with a circumference of ~ 480 m that incorporates large aperture (60 cm diameter) magnets. There are many challenges in the design. In order to incorporate the Orbit Combination section (OCS), used for injecting the pion beam into the ring, a dispersion suppressor is needed adjacent to the OCS . Concurrently, in order to maximize the number of useful muon decays, strong bending dipoles are needed in the arcs to minimize the arcmore » length. These dipoles create strong chromatic effects, which need to be corrected by nonlinear sextupole elements in the ring. In this paper, a FODO racetrack ring design and its optimization using sextupolar fields via both a Genetic Algorithm (GA) and a Simulated Annealing (SA) algorithm will be discussed.« less

Copper-Catalyzed Cyclopropanol Ring Opening Csp(3)-Csp(3) Cross-Couplings with (Fluoro)Alkyl Halides.

PubMed

Ye, Zhishi; Gettys, Kristen E; Shen, Xingyu; Dai, Mingji

2015-12-18

Novel and general copper-catalyzed cyclopropanol ring opening cross-coupling reactions with difluoroalkyl bromides, perfluoroalkyl iodides, monofluoroalkyl bromides, and 2-bromo-2-alkylesters to synthesize various β-(fluoro)alkylated ketones are reported. The reactions feature mild conditions and excellent functional group compatibility and can be scaled up to gram scale. Preliminary mechanistic studies suggest the involvement of radical intermediates. The difluoroalkyl-alkyl cross-coupling products can also be readily converted to more valuable and diverse gem-difluoro-containing compounds by taking advantage of the carbonyl group resulting from cyclopropanol ring opening.

Non-Performativity of University and Subjectification of Students: The Question of Equality and Diversity in UK Universities

ERIC Educational Resources Information Center

Kimura, Maki

2014-01-01

Universities in the United Kingdom have experienced a transformation in the context of the government's initiatives to widen participation and rapid socio-economic changes locally and globally. With more diverse students entering higher education, universities need to consider how they can create an inclusive environment. Indeed, in order to…

Innermost Van Allen Radiation Belt for High Energy Protons at Saturn

NASA Technical Reports Server (NTRS)

Cooper, John F.

2008-01-01

The high energy proton radiation belts of Saturn are energetically dominated by the source from cosmic ray albedo neutron decay (CRAND), trapping of protons from beta decay of neutrons emitted from galactic cosmic ray nuclear interactions with the main rings. These belts were originally discovered in wide gaps between the A-ring, Janus/Epimetheus, Mimas, and Enceladus. The narrow F and G rings significant affected the CRAND protons but did not produce total depletion. Voyager 2 measurements subsequently revealed an outermost CRAND proton belt beyond Enceladus. Although the source rate is small, the trapping times limited by radial magnetospheric diffusion are very long, about ten years at peak measured flux inwards of the G ring, so large fluxes can accumulate unless otherwise limited in the trapping region by neutral gas, dust, and ring body interactions. One proposed final extension of the Cassini Orbiter mission would place perikrone in a 3000-km gap between the inner D ring and the upper atmosphere of Saturn. Experience with CRAND in the Earth's inner Van Allen proton belt suggests that a similar innermost belt might be found in this comparably wide region at Saturn. Radial dependence of magnetospheric diffusion, proximity to the ring neutron source, and northward magnetic offset of Saturn's magnetic equator from the ring plane could potentially produce peak fluxes several orders of magnitude higher than previously measured outside the main rings. Even brief passes through such an intense environment of highly penetrating protons would be a significant concern for spacecraft operations and science observations. Actual fluxes are limited by losses in Saturn's exospheric gas and in a dust environment likely comparable to that of the known CRAND proton belts. The first numerical model of this unexplored radiation belt is presented to determine limits on peak magnitude and radial profile of the proton flux distribution.

Stacking interactions between nitrogen-containing six-membered heterocyclic aromatic rings and substituted benzene: studies in solution and in the solid state.

PubMed

Gung, Benjamin W; Wekesa, Francis; Barnes, Charles L

2008-03-07

The stacking interactions between an aromatic ring and a pyridine or a pyrimidine ring are studied by using a series of triptycene-derived scaffolds. The indicative ratios of the syn and anti conformers were determined by variable-temperature NMR spectroscopy. The syn conformer aligns the attached aromatic ring and the heterocycle in a parallel-displaced orientation while the anti conformer sets the two rings apart from each other. Comparing to the corresponding control compounds where a benzene ring is in the position of the heterocycle, higher attractive interactions are observed as indicated by the higher syn/anti ratios. In general, the attractive interactions are much less sensitive to the substituent effects than the corresponding nonheterocycles. The greatest attractive interactions were observed between a pyrimidine ring and a N,N-dimethylaminobenzene, consistent with a predominant donor-acceptor interaction. The interactions between a pyridine ring and a substituted benzene ring show that the pyridine is comparable to that of a NO2- or a CN-substituted benzene ring except for the unpredictable substituent effects.

Kinoform optics applied to X-ray photon correlation spectroscopy.

PubMed

Sandy, A R; Narayanan, S; Sprung, M; Su, J-D; Evans-Lutterodt, K; Isakovic, A F; Stein, A

2010-05-01

Moderate-demagnification higher-order silicon kinoform focusing lenses have been fabricated to facilitate small-angle X-ray photon correlation spectroscopy (XPCS) experiments. The geometric properties of such lenses, their focusing performance and their applicability for XPCS measurements are described. It is concluded that one-dimensional vertical X-ray focusing via silicon kinoform lenses significantly increases the usable coherent flux from third-generation storage-ring light sources for small-angle XPCS experiments.

The Chloroplast Division Protein ARC6 Acts to Inhibit Disassembly of GDP-bound FtsZ2.

PubMed

Sung, Min Woo; Shaik, Rahamthulla; TerBush, Allan D; Osteryoung, Katherine W; Vitha, Stanislav; Holzenburg, Andreas

2018-05-16

Chloroplasts host photosynthesis and fulfill other metabolic functions that are essential to plant life. They have to divide by binary fission to maintain their numbers throughout cycles of cell division. Chloroplast division is achieved by a complex ring-shaped division machinery located on both the inner (stromal) and the outer (cytosolic) side of the chloroplast envelope. The inner division ring (termed the Z ring) is formed by the assembly of tubulin-like FtsZ1 and FtsZ2 proteins. ARC6 is a key chloroplast division protein that interacts with the Z ring. ARC6 spans the inner envelope membrane, is known to stabilize or maintain the Z ring, and anchors the Z ring to the inner membrane through interaction with FtsZ2. The underlying mechanism of Z-ring stabilization is not well understood. Here, biochemical and structural characterization of ARC6 was conducted using light scattering, sedimentation, and light and transmission electron microscopy. The recombinant protein was purified as a dimer. The results indicated that a truncated form of ARC6 (tARC6), representing the stromal portion of ARC6, affects FtsZ2 assembly without forming higher-order structures, and exerts its effect via FtsZ2 dynamics. tARC6 prevented GDP-induced FtsZ2 disassembly and caused a significant net increase in FtsZ2 assembly when GDP was present. Single particle analysis and 3D reconstruction were performed to elucidate the structural basis of ARC6 activity. Together, the data reveal that a dimeric form of tARC6 binds to FtsZ2 filaments and does not increase FtsZ polymerization rates but rather inhibits GDP-associated FtsZ2 disassembly. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

{pi}-{pi} Interactions and magnetic properties in a series of hybrid inorganic-organic crystals

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

Gonzalez, M.; Lemus-Santana, A.A.; Rodriguez-Hernandez, J.

The series of hybrid inorganic-organic solids T(Im){sub 2}[Ni(CN){sub 4}] with T=Fe, Co, Ni and Im=imidazole were prepared by soft chemical routes from aqueous solutions of the involved building units: imidazole, T{sup 2+} metal and the [Ni(CN){sub 4}]{sup 2-} anionic block. The obtained samples were characterized from infrared and UV-vis spectroscopies, and thermogravimetric, X-ray diffraction and magnetic measurements. Anhydrous solids which crystallize with a monoclinic unit cell, in the I2/a space group with four formula units per cell (Z=4) were obtained. Their crystal structure was solved ab initio from the recorded X-ray powder patterns and then refined by the Rietveld method.more » The metal T is found with octahedral coordination to four N ends of CN groups and two imidazole molecules while the inner Ni atom preserves its planar coordination. The system of layers remains stacked in an ordered 3D structure through dipole-dipole and {pi}-{pi} interactions between imidazole rings from neighboring layers. In this way, a pillared structure is achieved without requiring the coordination of both nitrogen atoms from imidazole ring. The recorded magnetic data indicate the occurrence of a predominant ferromagnetic interaction at low temperature for Co and Ni but not for Fe. Such magnetic ordering is more favorable for Ni with transition temperature of 14.67 K, which was ascribed to the relatively high polarizing power for this metal. Within the considered T metals, to nickel the highest electron-withdrawing ability corresponds and this leads to an increase for the metal-ligand electron clouds overlapping and to a stronger {pi}-{pi} attractive interaction, two factors that result into a higher magnetic ordering temperature. - Graphical Abstract: Magnetic ordering through the {pi}-{pi} interaction between the imidazole rings. Highlights: Black-Right-Pointing-Pointer Hybrid inorganic-organic solids. Black-Right-Pointing-Pointer Hybrid inorganic-organic molecular based magnets. Black-Right-Pointing-Pointer Ferromagnetic interaction through {pi}-{pi} stacking of imidazole rings. Black-Right-Pointing-Pointer Organic pillars formed through {pi}-{pi} stacking.« less

Computational Study of a Vortex-Ring Pair Interacting with a Constant-Temperature Heated Wall

NASA Astrophysics Data System (ADS)

Jabbar, Hussam; Naguib, Ahmed

2017-11-01

Impinging jets are used widely in industrial and manufacturing processes because of their ability to increase the heat transfer rate from the impingement surface. The vortical structures of these jets have an important influence on the heat transfer; by affecting the thermal boundary layer (TBL) during their interaction with the wall. In order to better understand the physics of this interaction, particularly when pairing of two vortices happens near the wall, a simplified model problem of two isolated vortex rings interacting with a flat wall is investigated computationally using ANSYS FLUENT 17.1. Observations of the vorticity field, the temperature field, the wall shear stress, the TBL and the Nusselt number (Nu) provide insight into the association of local Nu maxima/minima with different flow features. The results provide physical understanding of the flow processes leading to enhancement/deterioration of Nu due to vortex-wall interaction. Additionally, the characteristics of the vortical structures are quantified, and possible correlations between the temporal development of these characteristics and the evolution of the maximum/minimum Nu are investigated. The results are compared to those involving a single vortex ring in order to understand the effect of vortex pairing. This work is supported by NSF Grant Number CBET-1603720. Hussam Jabbar also acknowledges the fellowship support from Higher Committee for Education Development in Iraq (HCED).

Thalamic nuclei convey diverse contextual information to layer 1 of visual cortex

PubMed Central

Imhof, Fabia; Martini, Francisco J.; Hofer, Sonja B.

2017-01-01

Sensory perception depends on the context within which a stimulus occurs. Prevailing models emphasize cortical feedback as the source of contextual modulation. However, higher-order thalamic nuclei, such as the pulvinar, interconnect with many cortical and subcortical areas, suggesting a role for the thalamus in providing sensory and behavioral context – yet the nature of the signals conveyed to cortex by higher-order thalamus remains poorly understood. Here we use axonal calcium imaging to measure information provided to visual cortex by the pulvinar equivalent in mice, the lateral posterior nucleus (LP), as well as the dorsolateral geniculate nucleus (dLGN). We found that dLGN conveys retinotopically precise visual signals, while LP provides distributed information from the visual scene. Both LP and dLGN projections carry locomotion signals. However, while dLGN inputs often respond to positive combinations of running and visual flow speed, LP signals discrepancies between self-generated and external visual motion. This higher-order thalamic nucleus therefore conveys diverse contextual signals that inform visual cortex about visual scene changes not predicted by the animal’s own actions. PMID:26691828

Improved venous suppression on renal MR angiography with recessed elliptical centric ordering of K-space.

PubMed

Ho, Bernard; Chao, Minh; Zhang, Hong Lei; Watts, Richard; Prince, Martin R

2003-01-01

To evaluate recessed elliptical centric ordering of k-space in renal magnetic resonance (MR) angiography. All imaging was performed on the same 1.5 T MR imaging system (GE Signa CVi) using the body coil for signal transmission and a phased array coil for reception. Gd, 30 ml, was injected manually at 2 ml/sec timed with automatic triggering (SmartPrep). In thirty patients using standard elliptical centric ordering, the scanner paused 8 seconds between detection of the leading edge of the Gd bolus and initiation of scanning beginning with the center of k-space. For the recessed-elliptical centric ordering in 20 consecutive patients, this delay was reduced to 4 seconds but the absolute center of k-space recessed in by 4 seconds such that in all patients the absolute center of k-space was acquired 8 seconds after detecting the leading edge of the bolus. On the arterial phase images signal-to-noise ratio (SNR) was measured in the aorta, each renal artery and vein and contrast-to-noise ratio (CNR) was measured relative to subcutaneous fat. The standard deviation of signal outside the patient was considered to be "noise" for calculation of SNR and CNR. Incidence of ringing artifact in the aorta and renal veins was noted. Aorta SNR and CNR was significantly higher with the recessed technique (p = 0.02) and the ratio of renal artery signal to renal vein signal was higher with the recessed technique, 4 ± 2, compared to standard elliptical centric, 3 ± 2 (p = 0.03). Ringing artifact was also reduced with the recessed technique in both the aorta and renal veins. Gadolinium-enhanced renal MR angiography is improved by recessing the absolute center of k-space.

A Comparative Study of Phosphoric Acid-doped m-PBI Membranes

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

Perry, Kelly A; More, Karren Leslie; Payzant, E Andrew

2014-01-01

Phosphoric acid (PA)-doped m-polybenzimidazole (PBI) membranes used in high temperature fuel cells and hydrogen pumps were prepared by a conventional imbibing process and a sol-gel fabrication process. A comparative study was conducted to investigate the critical properties of PA doping levels, ionic conductivities, mechanical properties, and molecular ordering. This systematic study found that sol-gel PA-doped m-PBI membranes were able to absorb higher acid doping levels and to achieve higher ionic conductivities than conventionally imbibed membranes when treated in an equivalent manner. Even at similar acid loadings, the sol-gel membranes exhibited higher ionic conductivities. Heat treatment of conventionally imbibed membranes withmore » 29wt% solids caused a significant reduction in mechanical properties; conversely, sol-gel membranes exhibited an enhancement in mechanical properties. From X-ray structural studies and atomistic simulations, both conventionally imbibed and sol-gel membranes exhibited d-spacings of 3.5 and 4.6 , which were tentatively attributed to parallel ring stacking and staggered side-to-side packing, respectively, of the imidazole rings in these aromatic hetercyclic polymers. An anisotropic staggered side-to-side chain packing present in the conventional membranes may be root to the reduction in mechanical properties.« less

Ultrasonic Resonance Spectroscopy of Composite Rings for Flywheel Rotors

NASA Technical Reports Server (NTRS)

Harmon, Laura M.; Baaklini, George Y.

2001-01-01

Flywheel energy storage devices comprising multilayered composite rotor systems are being studied extensively for utilization in the International Space Station. These composite material systems were investigated with a recently developed ultrasonic resonance spectroscopy technique. The system employs a swept frequency approach and performs a fast Fourier transform on the frequency spectrum of the response signal. In addition. the system allows for equalization of the frequency spectrum, providing all frequencies with equal amounts of energy to excite higher order resonant harmonics. Interpretation of the second fast Fourier transform, along with equalization of the frequency spectrum, offers greater assurance in acquiring and analyzing the fundamental frequency, or spectrum resonance spacing. The range of frequencies swept in a pitch-catch mode was varied up to 8 MHz, depending on the material and geometry of the component. Single and multilayered material samples, with and without known defects, were evaluated to determine how the constituents of a composite material system affect the resonant frequency. Amplitude and frequency changes in the spectrum and spectrum resonance spacing domains were examined from ultrasonic responses of a flat composite coupon, thin composite rings, and thick composite rings. Also, the ultrasonic spectroscopy responses from areas with an intentional delamination and a foreign material insert, similar to defects that may occur during manufacturing malfunctions, were compared with those from defect-free areas in thin composite rings. A thick composite ring with varying thickness was tested to investigate the full-thickness resonant frequency and any possible bulk interfacial bond issues. Finally, the effect on the frequency response of naturally occurring single and clustered voids in a composite ring was established.

Collision mechanics and the structure of planetary ring edges

NASA Technical Reports Server (NTRS)

Spaute, Dominique; Greenberg, Richard

1987-01-01

The present numerical simulation of collisional evolution, in the case of a hypothetical ring whose parameters are modeled after those of Saturn's rings, gives attention to changes in radial structure near the ring edges and notes that when random motion is in equilibrium, the rings tend to spread in order to conserve angular momentum while energy is dissipated in collisions. As long as random motion is damped, ring edges may contract rather than spread, producing a concentration of material at the ring edges. For isotropic scattering, damping dominates for a coefficient of restitution of velocity value of up to 0.83.

Synthetic Biology of Proteins: Tuning GFPs Folding and Stability with Fluoroproline

PubMed Central

Steiner, Thomas; Hess, Petra; Bae, Jae Hyun; Wiltschi, Birgit; Moroder, Luis; Budisa, Nediljko

2008-01-01

Background Proline residues affect protein folding and stability via cis/trans isomerization of peptide bonds and by the Cγ-exo or -endo puckering of their pyrrolidine rings. Peptide bond conformation as well as puckering propensity can be manipulated by proper choice of ring substituents, e.g. Cγ-fluorination. Synthetic chemistry has routinely exploited ring-substituted proline analogs in order to change, modulate or control folding and stability of peptides. Methodology/Principal Findings In order to transmit this synthetic strategy to complex proteins, the ten proline residues of enhanced green fluorescent protein (EGFP) were globally replaced by (4R)- and (4S)-fluoroprolines (FPro). By this approach, we expected to affect the cis/trans peptidyl-proline bond isomerization and pyrrolidine ring puckering, which are responsible for the slow folding of this protein. Expression of both protein variants occurred at levels comparable to the parent protein, but the (4R)-FPro-EGFP resulted in irreversibly unfolded inclusion bodies, whereas the (4S)-FPro-EGFP led to a soluble fluorescent protein. Upon thermal denaturation, refolding of this variant occurs at significantly higher rates than the parent EGFP. Comparative inspection of the X-ray structures of EGFP and (4S)-FPro-EGFP allowed to correlate the significantly improved refolding with the Cγ-endo puckering of the pyrrolidine rings, which is favored by 4S-fluorination, and to lesser extents with the cis/trans isomerization of the prolines. Conclusions/Significance We discovered that the folding rates and stability of GFP are affected to a lesser extent by cis/trans isomerization of the proline bonds than by the puckering of pyrrolidine rings. In the Cγ-endo conformation the fluorine atoms are positioned in the structural context of the GFP such that a network of favorable local interactions is established. From these results the combined use of synthetic amino acids along with detailed structural knowledge and existing protein engineering methods can be envisioned as a promising strategy for the design of complex tailor-made proteins and even cellular structures of superior properties compared to the native forms. PMID:18301757

Deterministic phase slips in mesoscopic superconducting rings

PubMed Central

Petković, I.; Lollo, A.; Glazman, L. I.; Harris, J. G. E.

2016-01-01

The properties of one-dimensional superconductors are strongly influenced by topological fluctuations of the order parameter, known as phase slips, which cause the decay of persistent current in superconducting rings and the appearance of resistance in superconducting wires. Despite extensive work, quantitative studies of phase slips have been limited by uncertainty regarding the order parameter's free-energy landscape. Here we show detailed agreement between measurements of the persistent current in isolated flux-biased rings and Ginzburg–Landau theory over a wide range of temperature, magnetic field and ring size; this agreement provides a quantitative picture of the free-energy landscape. We also demonstrate that phase slips occur deterministically as the barrier separating two competing order parameter configurations vanishes. These results will enable studies of quantum and thermal phase slips in a well-characterized system and will provide access to outstanding questions regarding the nature of one-dimensional superconductivity. PMID:27882924

Deterministic phase slips in mesoscopic superconducting rings.

PubMed

Petković, I; Lollo, A; Glazman, L I; Harris, J G E

2016-11-24

The properties of one-dimensional superconductors are strongly influenced by topological fluctuations of the order parameter, known as phase slips, which cause the decay of persistent current in superconducting rings and the appearance of resistance in superconducting wires. Despite extensive work, quantitative studies of phase slips have been limited by uncertainty regarding the order parameter's free-energy landscape. Here we show detailed agreement between measurements of the persistent current in isolated flux-biased rings and Ginzburg-Landau theory over a wide range of temperature, magnetic field and ring size; this agreement provides a quantitative picture of the free-energy landscape. We also demonstrate that phase slips occur deterministically as the barrier separating two competing order parameter configurations vanishes. These results will enable studies of quantum and thermal phase slips in a well-characterized system and will provide access to outstanding questions regarding the nature of one-dimensional superconductivity.

Deterministic phase slips in mesoscopic superconducting rings

DOE PAGES

Petković, Ivana; Lollo, A.; Glazman, L. I.; ...

2016-11-24

The properties of one-dimensional superconductors are strongly influenced by topological fluctuations of the order parameter, known as phase slips, which cause the decay of persistent current in superconducting rings and the appearance of resistance in superconducting wires. Despite extensive work, quantitative studies of phase slips have been limited by uncertainty regarding the order parameter’s free-energy landscape. Here we show detailed agreement between measurements of the persistent current in isolated flux-biased rings and Ginzburg–Landau theory over a wide range of temperature, magnetic field and ring size; this agreement provides a quantitative picture of the free-energy landscape. Furthermore, we also demonstrate thatmore » phase slips occur deterministically as the barrier separating two competing order parameter configurations vanishes. These results will enable studies of quantum and thermal phase slips in a well-characterized system and will provide access to outstanding questions regarding the nature of one-dimensional superconductivity.« less

Propagation and coherence properties of higher order partially coherent dark hollow beams in turbulence

NASA Astrophysics Data System (ADS)

Eyyuboğlu, Halil Tanyer

2008-02-01

We formulate and evaluate in terms of graphical outputs, source and receiver plane expressions, the complex degree of coherence, beam size variation and power in bucket performance for higher order partially coherent dark hollow beams propagating in turbulent atmosphere. Our formulation is able to cover square, rectangular, circular, elliptical geometries for dark hollow and flat-topped beams in one single expression. From the graphical outputs of the receiver plane, it is observed that higher order partially coherent dark hollow beams will initially develop an outer ring around a central lobe, but will eventually evolve towards a Gaussian shape as the propagation distance is extended. It is further observed that stronger turbulence levels and greater partial coherence have similar effects on beam profile. During propagation, modulus of complex degree of coherence of partially coherent dark hollow beams appears to rise above that of the source plane values, reaching as high as near unity. Beam size analysis shows that, among the types examined, (nearly) flat-topped beam experiences the least beam expansion. Power in bucket analysis indicates that lowest order square fully coherent dark beam offers the best power capturing.

Density Waves in Saturn's Rings from Cassini Radio Occultations

NASA Astrophysics Data System (ADS)

French, R. G.; Rappaport, N. J.; Marouf, E. A.; McGhee, C. A.

2005-12-01

The Cassini Radio Science Team conducted a set of optimized diametric occultations by Saturn and its rings from May to September 2005, providing 11 separate probes of Saturn's ionosphere and atmosphere, and 12 optical depth profiles of the complete ring system. Each event was observed by the stations of the Deep Space Net (DSN) at three radio frequencies (S, X, Ka bands, with corresponding wavelengths of ? = 13, 3.6, and 0.9 cm). Very accurate pointing by the spacecraft and ground antennas resulted in stable baseline signal levels, and the relatively large ring opening angle (B=19-25°) permitted us to probe even quite dense ring regions with excellent SNR. The RSS occultation technique enables us to recover very fine detailed radial structure by correcting for diffraction effects. Multiple occultation chords, covering a variety of ring longitudes and ring opening angles, reveal the structure of the rings in remarkable detail, including density and bending waves, satellite wakes, and subtle variations at the 100-m radius scale. Janus and Epimetheus are responsible for a particularly rich set of density waves, and their coorbital interactions result in a complex interplay of time-variable ring structure over the 8-year libration period of the two satellites. We compare the first-order 2:1, 4:3, 5:4, and 6:5 coorbital density waves from multiple occultation chords to linear density wave models based on a dynamical model of the orbital exchange between the moons. From the observed dispersion relation of the wave crests, we infer the surface mass density and eccentricity gradient of particle streamlines, and match the detailed shapes of the wave crests using a non-linear analysis. Second-order coorbital features are also evident, and there are even hints of third-order density waves in the high SNR radio occultation data.

Genetic wealth, population health: Major histocompatibility complex variation in captive and wild ring-tailed lemurs (Lemur catta).

PubMed

Grogan, Kathleen E; Sauther, Michelle L; Cuozzo, Frank P; Drea, Christine M

2017-10-01

Across species, diversity at the major histocompatibility complex (MHC) is critical to individual disease resistance and, hence, to population health; however, MHC diversity can be reduced in small, fragmented, or isolated populations. Given the need for comparative studies of functional genetic diversity, we investigated whether MHC diversity differs between populations which are open, that is experiencing gene flow, versus populations which are closed, that is isolated from other populations. Using the endangered ring-tailed lemur ( Lemur catta ) as a model, we compared two populations under long-term study: a relatively "open," wild population ( n  = 180) derived from Bezà Mahafaly Special Reserve, Madagascar (2003-2013) and a "closed," captive population ( n  = 121) derived from the Duke Lemur Center (DLC, 1980-2013) and from the Indianapolis and Cincinnati Zoos (2012). For all animals, we assessed MHC-DRB diversity and, across populations, we compared the number of unique MHC-DRB alleles and their distributions. Wild individuals possessed more MHC-DRB alleles than did captive individuals, and overall, the wild population had more unique MHC-DRB alleles that were more evenly distributed than did the captive population. Despite management efforts to maintain or increase genetic diversity in the DLC population, MHC diversity remained static from 1980 to 2010. Since 2010, however, captive-breeding efforts resulted in the MHC diversity of offspring increasing to a level commensurate with that found in wild individuals. Therefore, loss of genetic diversity in lemurs, owing to small founder populations or reduced gene flow, can be mitigated by managed breeding efforts. Quantifying MHC diversity within individuals and between populations is the necessary first step to identifying potential improvements to captive management and conservation plans.

2-Octyl thiophene based three ring mesogens: solid state (13)C NMR and XRD investigations.

PubMed

Veeraprakash, B; Lobo, Nitin P; Narasimhaswamy, T; Mandal, A B

2015-08-14

2-Octyl thiophene based three-ring mesogens namely 4-n-alkoxyphenyl 4-(5-n-octyl-2-thienyl)benzoates are synthesized by employing palladium acetate based direct arylation. The alkoxy terminal is varied with even carbons from C2 to C14 and enantiotropic polymesomorphism is noticed for all the homologs. Accordingly, phase sequence consisting of nematic, smectic A, smectic C and smectic B is seen for mesogens with terminal chains C6, C8, C10 and C12 on cooling the isotropic phase. For mesogens with C2, C4, C8 and C10 terminal alkoxy chains, the mesophase assignment from hot-stage optical microscopy and differential scanning calorimetry is further confirmed by variable temperature powder X-ray diffraction measurements. The appearance of smectic B phase is established by noticing sharp and intense peaks in both small-angle and wide-angle regions. For a representative mesogen, i.e. T10, high-resolution solid-state (13)C NMR investigations are carried out in all the phases, viz. nematic, smectic A, smectic C and smectic B phases. The orientational order parameters calculated from (13)C-(1)H dipolar couplings from 2D SAMPI-4 experiments are found to be 0.44, 0.67, 0.73 and 0.79 in nematic, smectic A, smectic C and smectic B mesophases for the center phenyl ring respectively. Remarkably, the thiophene order parameter in all mesophases is found to be higher than that of phenyl rings and is explained by considering the molecular shape, which has a terminal bend. Further, the mesogens are found to be photoemissive in chloroform solution with an emission band at ∼410 nm.

Analysis of the electron density features of small boron clusters and the effects of doping with C, P, Al, Si, and Zn: Magic B7P and B8Si clusters

NASA Astrophysics Data System (ADS)

Saha, P.; Rahane, A. B.; Kumar, V.; Sukumar, N.

2016-05-01

Boron atomic clusters show several interesting and unusual size-dependent features due to the small covalent radius, electron deficiency, and higher coordination number of boron as compared to carbon. These include aromaticity and a diverse array of structures such as quasi-planar, ring or tubular shaped, and fullerene-like. In the present work, we have analyzed features of the computed electron density distributions of small boron clusters having up to 11 boron atoms, and investigated the effect of doping with C, P, Al, Si, and Zn atoms on their structural and physical properties, in order to understand the bonding characteristics and discern trends in bonding and stability. We find that in general there are covalent bonds as well as delocalized charge distribution in these clusters. We associate the strong stability of some of these planar/quasiplanar disc-type clusters with the electronic shell closing with effectively twelve delocalized valence electrons using a disc-shaped jellium model. {{{{B}}}9}-, B10, B7P, and B8Si, in particular, are found to be exceptional with very large gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, and these are suggested to be magic clusters.

A FODO racetrack ring for nuSTORM: design and optimization

DOE PAGES

Liu, A.; Bross, A.; Neuffer, D.

2017-07-17

Here, the goal of nuSTORM is to provide well-defined neutrino beams for precise measurements of neutrino cross-sections and oscillations. The nuSTORM decay ring is a compact racetrack storage ring with a circumference of ~ 480 m that incorporates large aperture (60 cm diameter) magnets. There are many challenges in the design. In order to incorporate the Orbit Combination section (OCS), used for injecting the pion beam into the ring, a dispersion suppressor is needed adjacent to the OCS . Concurrently, in order to maximize the number of useful muon decays, strong bending dipoles are needed in the arcs to minimize themore » arc length. These dipoles create strong chromatic effects, which need to be corrected by nonlinear sextupole elements in the ring. In this paper, a FODO racetrack ring design and its optimization using sextupolar fields via both a Genetic Algorithm (GA) and a Simulated Annealing (SA) algorithm will be discussed.« less

Chromatin-Bound Cullin-Ring Ligases: Regulatory Roles in DNA Replication and Potential Targeting for Cancer Therapy

PubMed Central

Jang, Sang-Min; Redon, Christophe E.; Aladjem, Mirit I.

2018-01-01

Cullin-RING (Really Interesting New Gene) E3 ubiquitin ligases (CRLs), the largest family of E3 ubiquitin ligases, are functional multi-subunit complexes including substrate receptors, adaptors, cullin scaffolds, and RING-box proteins. CRLs are responsible for ubiquitination of ~20% of cellular proteins and are involved in diverse biological processes including cell cycle progression, genome stability, and oncogenesis. Not surprisingly, cullins are deregulated in many diseases and instances of cancer. Recent studies have highlighted the importance of CRL-mediated ubiquitination in the regulation of DNA replication/repair, including specific roles in chromatin assembly and disassembly of the replication machinery. The development of novel therapeutics targeting the CRLs that regulate the replication machinery and chromatin in cancer is now an attractive therapeutic strategy. In this review, we summarize the structure and assembly of CRLs and outline their cellular functions and their diverse roles in cancer, emphasizing the regulatory functions of nuclear CRLs in modulating the DNA replication machinery. Finally, we discuss the current strategies for targeting CRLs against cancer in the clinic. PMID:29594129

Si-rich SiNx based Kerr switch enables optical data conversion up to 12 Gbit/s

PubMed Central

Lin, Gong-Ru; Su, Sheng-Pin; Wu, Chung-Lun; Lin, Yung-Hsiang; Huang, Bo-Ji; Wang, Huai-Yung; Tsai, Cheng-Ting; Wu, Chih-I; Chi, Yu-Chieh

2015-01-01

Silicon photonic interconnection on chip is the emerging issue for next-generation integrated circuits. With the Si-rich SiNx micro-ring based optical Kerr switch, we demonstrate for the first time the wavelength and format conversion of optical on-off-keying data with a bit-rate of 12 Gbit/s. The field-resonant nonlinear Kerr effect enhances the transient refractive index change when coupling the optical data-stream into the micro-ring through the bus waveguide. This effectively red-shifts the notched dip wavelength to cause the format preserved or inversed conversion of data carried by the on-resonant or off-resonant probe, respectively. The Si quantum dots doped Si-rich SiNx strengthens its nonlinear Kerr coefficient by two-orders of magnitude higher than that of bulk Si or Si3N4. The wavelength-converted and cross-amplitude-modulated probe data-stream at up to 12-Gbit/s through the Si-rich SiNx micro-ring with penalty of −7 dB on transmission has shown very promising applicability to all-optical communication networks. PMID:25923653

Si-rich SiNx based Kerr switch enables optical data conversion up to 12 Gbit/s.

PubMed

Lin, Gong-Ru; Su, Sheng-Pin; Wu, Chung-Lun; Lin, Yung-Hsiang; Huang, Bo-Ji; Wang, Huai-Yung; Tsai, Cheng-Ting; Wu, Chih-I; Chi, Yu-Chieh

2015-04-29

Silicon photonic interconnection on chip is the emerging issue for next-generation integrated circuits. With the Si-rich SiNx micro-ring based optical Kerr switch, we demonstrate for the first time the wavelength and format conversion of optical on-off-keying data with a bit-rate of 12 Gbit/s. The field-resonant nonlinear Kerr effect enhances the transient refractive index change when coupling the optical data-stream into the micro-ring through the bus waveguide. This effectively red-shifts the notched dip wavelength to cause the format preserved or inversed conversion of data carried by the on-resonant or off-resonant probe, respectively. The Si quantum dots doped Si-rich SiNx strengthens its nonlinear Kerr coefficient by two-orders of magnitude higher than that of bulk Si or Si3N4. The wavelength-converted and cross-amplitude-modulated probe data-stream at up to 12-Gbit/s through the Si-rich SiNx micro-ring with penalty of -7 dB on transmission has shown very promising applicability to all-optical communication networks.

Simple-structured capillary-force-dominated tunable-focus liquid lens based on the higher-order-harmonic resonance of a piezoelectric ring transducer.

PubMed

Feng, Guo-Hua; Liu, Jun-Hao

2013-02-01

This paper proposes a tunable-focus liquid lens implemented with a simple cylindrical container structure and liquid as the lens material. The cylindrical container was constructed using a Pb [Zr(0.52)Ti(0.48)]O(3) (PZT) ring transducer and a polydimethylsiloxane membrane that was attached to a flat side of the transducer. The free surface of the liquid in the cylindrical container can be driven as a static-like convex lens with different curvatures because the higher-order harmonic resonance of the PZT transducer was electrically controlled. Based on a capillary-force-dominant design, the activated liquid lens maintained surface curvature in an arbitrary orientation without a gravitational effect. Profiles of the liquid lenses were characterized with the driving voltages of the transducer ranging from 12 to 60 V peak-to-peak (Vpp) at a resonant frequency of 460 kHz. The temperature effects on the lenses caused by the continuous operation of the transducer were measured. Images showed the various curvatures of the lenses with a range of actuation voltages. A change in focal length of eight times (5.72 to 46.03 cm) was demonstrated within the 10 Vpp variation of the driving voltage. For the characterized liquid lenses, the distortion was less than 2%, and the modulation transfer function reached 63 line pairs per mm (lp/mm) using ZEMAX analysis.

B-ring-aryl substituted luotonin A analogues with a new binding mode to the topoisomerase 1-DNA complex show enhanced cytotoxic activity.

PubMed

González-Ruiz, Víctor; Pascua, Irene; Fernández-Marcelo, Tamara; Ribelles, Pascual; Bianchini, Giulia; Sridharan, Vellaisamy; Iniesta, Pilar; Ramos, M Teresa; Olives, Ana I; Martín, M Antonia; Menéndez, J Carlos

2014-01-01

Topoisomerase 1 inhibition is an important strategy in targeted cancer chemotherapy. The drugs currently in use acting on this enzyme belong to the family of the camptothecins, and suffer severe limitations because of their low stability, which is associated with the hydrolysis of the δ-lactone moiety in their E ring. Luotonin A is a natural camptothecin analogue that lacks this functional group and therefore shows a much-improved stability, but at the cost of a lower activity. Therefore, the development of luotonin A analogues with an increased potency is important for progress in this area. In the present paper, a small library of luotonin A analogues modified at their A and B rings was generated by cerium(IV) ammonium nitrate-catalyzed Friedländer reactions. All analogues showed an activity similar or higher than the natural luotonin A in terms of topoisomerase 1 inhibition and some compounds had an activity comparable to that of camptothecin. Furthermore, most compounds showed a better activity than luotonin A in cell cytotoxicity assays. In order to rationalize these results, the first docking studies of luotonin-topoisomerase 1-DNA ternary complexes were undertaken. Most compounds bound in a manner similar to luotonin A and to standard topoisomerase poisons such as topotecan but, interestingly, the two most promising analogues, bearing a 3,5-dimethylphenyl substituent at ring B, docked in a different orientation. This binding mode allows the hydrophobic moiety to be shielded from the aqueous environment by being buried between the deoxyribose belonging to the G(+1) guanine and Arg364 in the scissile strand and the surface of the protein and a hydrogen bond between the D-ring carbonyl and the basic amino acid. The discovery of this new binding mode and its associated higher inhibitory potency is a significant advance in the design of new topoisomerase 1 inhibitors.

Apse-Alignment of the Uranian Rings

NASA Technical Reports Server (NTRS)

Mosqueira, I.; Estrada, P. R.

2000-01-01

An explanation of the dynamical mechanism for apse-alignment of the eccentric Uranian rings is necessary before observations can be used to determine properties such as ring masses, particle sizes, and elasticities. The leading model relies on the ring self-gravity to accomplish this task, yet it yields equilibrium masses which are not in accord with Voyager radio measurements. We explore possible solutions such that the self-gravity and the collisional terms are both involved in the process of apse-alignment. We consider limits that correspond to a hot and a cold ring, and show that pressure terms may play a significant role in the equilibrium conditions for the narrow Uranian rings. In the cold ring case, where the scale height of the ring near periapse is comparable to the ring particle size, we introduce a new pressure correction pertaining to a region of the ring where the particles are locked in their relative positions and jammed against their neighbors, and the velocity dispersion is so low that the collisions are nearly elastic. In this case, we find a solution such that the ring self-gravity maintains apse-alignment against both differential precession (m = 1 mode) and the fluid pressure. We apply this model to the Uranian alpha ring, and show that, compared to the previous self-gravity model, the mass estimate for this ring increases by an order of magnitude. In the case of a hot ring, where the scale height can reach a value as much as fifty times larger than a particle size, we find velocity dispersion profiles that result in pressure forces which act in such a way as to alter the ring equilibrium conditions, again leading to a ring mass increase of an order of magnitude; however, such a velocity dispersion profile would require a different mechanism than is currently envisioned for establishing heating/cooling balance in a finite-sized, inelastic particle ring. Finally, we introduce an important correction to the model of Chiang and Goldreich.

Seasonal temperature and precipitation recorded in the intra-annual oxygen isotope pattern of meteoric water and tree-ring cellulose

NASA Astrophysics Data System (ADS)

Schubert, Brian A.; Jahren, A. Hope

2015-10-01

Modern and ancient wood is a valuable terrestrial record of carbon ultimately derived from the atmosphere and oxygen inherited from local meteoric water. Many modern and fossil wood specimens display rings sufficiently thick for intra-annual sampling, and analytical techniques are rapidly improving to allow for precise carbon and oxygen isotope measurements on very small samples, yielding unprecedented resolution of seasonal isotope records. However, the interpretation of these records across diverse environments has been problematic because a unifying model for the quantitative interpretation of seasonal climate parameters from oxygen isotopes in wood is lacking. Towards such a model, we compiled a dataset of intra-ring oxygen isotope measurements on modern wood cellulose (δ18Ocell) from 33 globally distributed sites. Five of these sites represent original data produced for this study, while the data for the other 28 sites were taken from the literature. We defined the intra-annual change in oxygen isotope value of wood cellulose [Δ(δ18Ocell)] as the difference between the maximum and minimum δ18Ocell values determined within the ring. Then, using the monthly-resolved dataset of the oxygen isotope composition of meteoric water (δ18OMW) provided by the Global Network of Isotopes in Precipitation database, we quantified the empirical relationship between the intra-annual change in meteoric water [Δ(δ18OMW)] and Δ(δ18Ocell). We then used monthly-resolved datasets of temperature and precipitation to develop a global relationship between Δ(δ18OMW) and maximum/minimum monthly temperatures and winter/summer precipitation amounts. By combining these relationships we produced a single equation that explains much of the variability in the intra-ring δ18Ocell signal through only changes in seasonal temperature and precipitation amount (R2 = 0.82). We show how our recent model that quantifies seasonal precipitation from intra-ring carbon isotope profiles can be incorporated into the oxygen model above in order to separately quantify both seasonal temperature and seasonal precipitation. Determination of seasonal climate variation using high-resolution isotopes in tree-ring records makes possible a new understanding of the seasonal fluctuations that control the environmental conditions to which organisms are subject, both during recent history and in the geologic past.

Parametric design analysis of a hybrid composite flywheel using a laminated central disc and a filament wound outer ring

NASA Astrophysics Data System (ADS)

Nimmer, R. P.

1980-09-01

A hybrid flywheel design concept based on the use of a laminated central disk with a filament-wound outer ring is analyzed for several different combinations of composite materials. Some of the results of this study are: (1) an optimized E-glass disk with Kevlar-49 outer ring offers the prospect of 30% additional energy density over a laminated disk without a ring; (2) a laminated S2-glass disk is capable of storing more energy per unit mass than an E-glass disk because of its higher tensile strength; and (3) the use of wound graphite outer rings with S2-glass disks leads to substantial reductions in the size of the interference fit while offering still higher energy densities than for a Kevlar-49 outer ring.

Dynamic characteristics of a multi-wavelength Brillouin-Raman fiber laser assisted by multiple four-wave mixing processes in a ring cavity

NASA Astrophysics Data System (ADS)

Shirazi, M. R.; Mohamed Taib, J.; De La Rue, R. M.; Harun, S. W.; Ahmad, H.

2015-03-01

Dynamic characteristics of a multi-wavelength Brillouin-Raman fiber laser (MBRFL) assisted by four-wave mixing have been investigated through the development of Stokes and anti-Stokes lines under different combinations of Brillouin and Raman pump power levels and different Raman pumping schemes in a ring cavity. For a Stokes line of order higher than three, the threshold power was less than the saturation power of its last-order Stokes line. By increasing the Brillouin pump power, the nth order anti-Stokes and the (n+4)th order Stokes power levels were unexpectedly increased almost the same before the Stokes line threshold power. It was also found out that the SBS threshold reduction (SBSTR) depended linearly on the gain factor for the 1st and 2nd Stokes lines, as the first set. This relation for the 3rd and 4th Stokes lines as the second set, however, was almost linear with the same slope before SBSTR -6 dB, then, it approached to the linear relation in the first set when the gain factor was increased to 50 dB. Therefore, the threshold power levels of Stokes lines for a given Raman gain can be readily estimated only by knowing the threshold power levels in which there is no Raman amplification.

Effect of Substitution on the Aniline Moiety of the GPR88 Agonist 2-PCCA: Synthesis, Structure-Activity Relationships, and Molecular Modeling Studies.

PubMed

Jin, Chunyang; Decker, Ann M; Harris, Danni L; Blough, Bruce E

2016-10-19

GPR88, an orphan receptor richly expressed in the striatum, is implicated in a number of basal ganglia-associated disorders. In order to elucidate the functions of GPR88, an in vivo probe appropriate for CNS investigation is required. We previously reported that 2-PCCA was able to modulate GPR88-mediated cAMP production through a Gα i -coupled pathway. Early structure-activity relationship (SAR) studies suggested that the aniline moiety of 2-PCCA is a suitable site for diverse modifications. Aimed at elucidating structural requirements in this region, we have designed and synthesized a series of analogues bearing a variety of substituents at the phenyl ring of the aniline moiety. Several compounds (e.g., 5j, 5o) showed improved or comparable potency, but have lower lipophilicity than 2-PCCA (clogP 6.19). These compounds provide the basis for further optimization to probe GPR88 in vivo functions. Computational studies confirmed the SAR trends and supported the notion that 4'-substituents on the biphenyl ring exit through a largely hydrophobic binding site to the extracellular loop.

Serotonergic Function, Two-Mode Models of Self-Regulation, and Vulnerability to Depression: What Depression Has in Common with Impulsive Aggression

ERIC Educational Resources Information Center

Carver, Charles S.; Johnson, Sheri L.; Joormann, Jutta

2008-01-01

Evidence from diverse literatures supports the viewpoint that two modes of self-regulation exist, a lower-order system that responds quickly to associative cues of the moment and a higher-order system that responds more reflectively and planfully; that low serotonergic function is linked to relative dominance of the lower-order system; that how…

Accuracy enhancement of laser induced breakdown spectra using permittivity and size optimized plasma confinement rings.

PubMed

Li, An; Guo, Shuai; Wazir, Nasrullah; Chai, Ke; Liang, Liang; Zhang, Min; Hao, Yan; Nan, Pengfei; Liu, Ruibin

2017-10-30

The inevitable problems in laser induced breakdown spectroscopy are matrix effect and statistical fluctuation of the spectral signal, which can be partly avoided by utilizing a proper confined unit. The dependences of spectral signal enhancement on relative permittivity were studied by varying materials to confine the plasma, which include polytetrafluoroethylene(PTFE), nylon/dacron, silicagel, and nitrile-butadiene rubber (NBR) with the relative permittivity 2.2, ~3.3, 3.6, 8~13, 15~22. We found that higher relative permittivity rings induce stronger enhancement ability, which restricts the energy dissipation of plasma better and due to the reflected electromagnetic wave from the wall of different materials, the electromagnetic field of plasma can be well confined and makes the distribution of plasma more orderly. The spectral intensities of the characteristic lines Si I 243.5 nm and Si I 263.1 nm increased approximately 2 times with relative permittivity values from 2.2 to ~20. The size dependent enhancement of PTFE was further checked and the maximum gain was realized by using a confinement ring with a diameter size of 5 mm and a height of 3 mm (D5mmH3mm), and the rings with D2mmH1mm and D3mmH2mm also show higher enhancement factor. In view of peak shift, peak lost and accidental peaks in the obtained spectra were properly treated in data progressing; the spectral fluctuation decreased drastically for various materials with different relative permittivities as confined units, which means the core of plasma is stabilized, attributing to the confinement effect. Furthermore, the quantitative analysis in coal shows wonderful results-the prediction fitting coefficient R 2 reaches 0.98 for ash and 0.99 for both volatile and carbon.

Climatic Signals in Tree Rings of Heritiera fomes Buch.-Ham. in the Sundarbans, Bangladesh

PubMed Central

Chowdhury, Md. Qumruzzaman; De Ridder, Maaike; Beeckman, Hans

2016-01-01

Mangroves occur along the coastlines throughout the tropics and sub-tropics, supporting a wide variety of resources and services. In order to understand the responses of future climate change on this ecosystem, we need to know how mangrove species have responded to climate changes in the recent past. This study aims at exploring the climatic influences on the radial growth of Heritiera fomes from a local to global scale. A total of 40 stem discs were collected at breast height position from two different zones with contrasting salinity in the Sundarbans, Bangladesh. All specimens showed distinct tree rings and most of the trees (70%) could be visually and statistically crossdated. Successful crossdating enabled the development of two zone-specific chronologies. The mean radial increment was significantly higher at low salinity (eastern) zone compared to higher salinity (western) zone. The two zone-specific chronologies synchronized significantly, allowing for the construction of a regional chronology. The annual and monsoon precipitation mainly influence the tree growth of H. fomes. The growth response to local precipitation is similar in both zones except June and November in the western zone, while the significant influence is lacking. The large-scale climatic drivers such as sea surface temperature (SST) of equatorial Pacific and Indian Ocean as well as the El Niño-Southern Oscillation (ENSO) revealed no teleconnection with tree growth. The tree rings of this species are thus an indicator for monsoon precipitation variations in Bangladesh. The wider distribution of this species from the South to South East Asian coast presents an outstanding opportunity for developing a large-scale tree-ring network of mangroves. PMID:26927229

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

Schneider, Glenn; Gaspar, Andras; Grady, Carol A.

We present new Hubble Space Telescope observations of three a priori known starlight-scattering circumstellar debris systems (CDSs) viewed at intermediate inclinations around nearby close-solar analog stars: HD 207129, HD 202628, and HD 202917. Each of these CDSs possesses ring-like components that are more massive analogs of our solar system's Edgeworth–Kuiper Belt. These systems were chosen for follow-up observations to provide imaging with higher fidelity and better sensitivity for the sparse sample of solar-analog CDSs that range over two decades in systemic ages, with HD 202628 and HD 207129 (both ∼2.3 Gyr) currently the oldest CDSs imaged in visible or near-IRmore » light. These deep (10–14 ks) observations, made with six-roll point-spread-function template visible-light coronagraphy using the Space Telescope Imaging Spectrograph, were designed to better reveal their angularly large debris rings of diffuse/low surface brightness, and for all targets probe their exo-ring environments for starlight-scattering materials that present observational challenges for current ground-based facilities and instruments. Contemporaneously also observing with a narrower occulter position, these observations additionally probe the CDS endo-ring environments that are seen to be relatively devoid of scatterers. We discuss the morphological, geometrical, and photometric properties of these CDSs also in the context of other CDSs hosted by FGK stars that we have previously imaged as a homogeneously observed ensemble. From this combined sample we report a general decay in quiescent-disk F {sub disk}/ F {sub star} optical brightness ∼ t {sup −0.8}, similar to what is seen at thermal IR wavelengths, and CDSs with a significant diversity in scattering phase asymmetries, and spatial distributions of their starlight-scattering grains.« less

Looking for age-related growth decline in natural forests: unexpected biomass patterns from tree rings and simulated mortality

USGS Publications Warehouse

Foster, Jane R.; D'Amato, Anthony W.; Bradford, John B.

2014-01-01

Forest biomass growth is almost universally assumed to peak early in stand development, near canopy closure, after which it will plateau or decline. The chronosequence and plot remeasurement approaches used to establish the decline pattern suffer from limitations and coarse temporal detail. We combined annual tree ring measurements and mortality models to address two questions: first, how do assumptions about tree growth and mortality influence reconstructions of biomass growth? Second, under what circumstances does biomass production follow the model that peaks early, then declines? We integrated three stochastic mortality models with a census tree-ring data set from eight temperate forest types to reconstruct stand-level biomass increments (in Minnesota, USA). We compared growth patterns among mortality models, forest types and stands. Timing of peak biomass growth varied significantly among mortality models, peaking 20–30 years earlier when mortality was random with respect to tree growth and size, than when mortality favored slow-growing individuals. Random or u-shaped mortality (highest in small or large trees) produced peak growth 25–30 % higher than the surviving tree sample alone. Growth trends for even-aged, monospecific Pinus banksiana or Acer saccharum forests were similar to the early peak and decline expectation. However, we observed continually increasing biomass growth in older, low-productivity forests of Quercus rubra, Fraxinus nigra, and Thuja occidentalis. Tree-ring reconstructions estimated annual changes in live biomass growth and identified more diverse development patterns than previous methods. These detailed, long-term patterns of biomass development are crucial for detecting recent growth responses to global change and modeling future forest dynamics.

Deep HST/STIS Visible-Light Imaging of Debris Systems Around Solar Analog Hosts

NASA Technical Reports Server (NTRS)

Schneider, Glenn; Grady, Carol A.; Stark, Christopher C.; Gaspar, Andras; Carson, Joseph; Debes, John H.; Henning, Thomas; Hines, Dean C.; Jang-Condell, Hannah; Kuchner, Marc J.

2016-01-01

We present new Hubble Space Telescope observations of three a priori known starlight-scattering circumstellar debris systems (CDSs) viewed at intermediate inclinations around nearby close-solar analog stars: HD 207129, HD202628, and HD 202917. Each of these CDSs possesses ring-like components that are more massive analogs of our solar systems Edgeworth Kuiper Belt. These systems were chosen for follow-up observations to provide imaging with higher fidelity and better sensitivity for the sparse sample of solar-analog CDSs that range over two decades in systemic ages, with HD 202628 and HD 207129 (both approx. 2.3 Gyr) currently the oldest CDSs imaged in visible or near-IR light. These deep (10-14 ks) observations, made with six-roll point-spread-function template visible-light coronagraphy using the Space Telescope Imaging Spectrograph, were designed to better reveal their angularly large debris rings of diffuse low surface brightness, and for all targets probe their exo-ring environments for starlight-scattering materials that present observational challenges for current ground-based facilities and instruments. Contemporaneously also observing with a narrower occulter position, these observations additionally probe the CDS endo-ring environments that are seen to be relatively devoid of scatterers. We discuss the morphological, geometrical, and photometric properties of these CDSs also in the context of other CDSs hosted by FGK stars that we have previously imaged as a homogeneously observed ensemble. From this combined sample we report a general decay in quiescent-disk F disk /F star optical brightness approx. t( exp.-0.8), similar to what is seen at thermal IR wavelengths, and CDSs with a significant diversity in scattering phase asymmetries, and spatial distributions of their starlight-scattering grains.

Mechanism of Polyubiquitination by Human Anaphase-Promoting Complex: RING Repurposing for Ubiquitin Chain Assembly

DOE PAGES

Brown, Nicholas G.; Watson, Edmond R.; Weissmann, Florian; ...

2014-10-09

Polyubiquitination by E2 and E3 enzymes is a predominant mechanism regulating protein function. Some RING E3s, including anaphase-promoting complex/cyclosome (APC), catalyze polyubiquitination by sequential reactions with two different E2s. An initiating E2 ligates ubiquitin to an E3-bound substrate. Another E2 grows a polyubiquitin chain on the ubiquitin-primed substrate through poorly defined mechanisms. Here in this paper we show that human APC’s RING domain is repurposed for dual functions in polyubiquitination. The canonical RING surface activates an initiating E2-ubiquitin intermediate for substrate modification. However, APC engages and activates its specialized ubiquitin chain-elongating E2 UBE2S in ways that differ from current paradigms.more » During chain assembly, a distinct APC11 RING surface helps deliver a substrate-linked ubiquitin to accept another ubiquitin from UBE2S. Our data define mechanisms of APC/UBE2S-mediated polyubiquitination, reveal diverse functions of RING E3s and E2s, and provide a framework for understanding distinctive RING E3 features specifying ubiquitin chain elongation.« less

Structure of an E3:E2~Ub Complex Reveals an Allosteric Mechanism Shared among RING/U-box Ligases

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

Pruneda, Jonathan N.; Littlefield, Peter J.; Soss, Sarah E.

2012-09-28

Despite the widespread importance of RING/U-box E3 ubiquitin ligases in ubiquitin (Ub) signaling, the mechanismby which this class of enzymes facilitates Ub transfer remains enigmatic. Here, we present a structural model for a RING/U-box E3:E2~Ub complex poised for Ub transfer. The model and additional analyses reveal that E3 binding biases dynamic E2~Ub ensembles toward closed conformations with enhanced reactivity for substrate lysines. We identify a key hydrogen bond between a highly conserved E3 side chain and an E2 backbone carbonyl, observed in all structures of active RING/ U-Box E3/E2 pairs, as the linchpin for allosteric activation of E2~Ub. The conformationalmore » biasing mechanism is generalizable across diverse E2s and RING/U-box E3s, but is not shared by HECT-type E3s. The results provide a structural model for a RING/ U-box E3:E2~Ub ligase complex and identify the long sought-after source of allostery for RING/UBox activation of E2~Ub conjugates.« less

Nanoring formation via in situ photoreduction of silver on a virus scaffold

NASA Astrophysics Data System (ADS)

Bayram, Serene S.; Zahr, Omar K.; Del Re, Julia; Szuchmacher Blum, Amy

2016-12-01

The fabrication of plasmonic nanorings remains of substantial interest by virtue of their enhanced electric and magnetic response to light fields which can be subsequently exploited in diverse applications. Scaling down the size of nanorings holds promise in creating artificial magnetism at wavelengths matching the solar spectrum. Nanosized bioscaffolds can be utilized to tackle the challenge of size reduction of metallic rings owing to their miniature features as well as their well-known biomineralization capacity. Herein, we use the tobacco mosaic virus coat protein as a command surface to grow and assemble silver nanoparticles into sub-30 nm rings. The versatility of TMV allows the formation of both solid rings and rings consisting of discrete nanoparticles that are characterized by UV-vis and TEM. The pH-dependent coulombic surface map along with the annular geometry of the protein aggregate allow the generation of rings with or without a central nanoparticle. Our silver rings are believed to be the smallest to date, and they can offer a test material for existing theories on metallic nanorings of this heretofore unreached size scale.

Nanoring formation via in situ photoreduction of silver on a virus scaffold.

PubMed

Bayram, Serene S; Zahr, Omar K; Del Re, Julia; Blum, Amy Szuchmacher

2016-12-02

The fabrication of plasmonic nanorings remains of substantial interest by virtue of their enhanced electric and magnetic response to light fields which can be subsequently exploited in diverse applications. Scaling down the size of nanorings holds promise in creating artificial magnetism at wavelengths matching the solar spectrum. Nanosized bioscaffolds can be utilized to tackle the challenge of size reduction of metallic rings owing to their miniature features as well as their well-known biomineralization capacity. Herein, we use the tobacco mosaic virus coat protein as a command surface to grow and assemble silver nanoparticles into sub-30 nm rings. The versatility of TMV allows the formation of both solid rings and rings consisting of discrete nanoparticles that are characterized by UV-vis and TEM. The pH-dependent coulombic surface map along with the annular geometry of the protein aggregate allow the generation of rings with or without a central nanoparticle. Our silver rings are believed to be the smallest to date, and they can offer a test material for existing theories on metallic nanorings of this heretofore unreached size scale.

DC-Powered Jumping Ring

ERIC Educational Resources Information Center

Jeffery, Rondo N.; Farhang, Amiri

2016-01-01

The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant…

Experimenatal analysis of the effect of cartilaginous rings on human tracheobronchial flow

NASA Astrophysics Data System (ADS)

Montoya Segnini, Jose; Bocanegra Evans, Humberto; Castillo, Luciano

2016-11-01

We present a set of high-resolution PIV experiments carried out in a refractive index-matched model of a trachea with cartilage rings at Re 2800. Results show a higher vorticity along the walls of the trachea in the model with cartilaginous rings as well as small recirculation areas on the upstream side of the wall cavities created by the rings. Furthermore, the ringed model experiences higher shear stress in the trachea due to the sudden change in the wall position created by the rings. Additionally, small recirculation areas are identified in the cavities between rings. For the smooth model, a stronger separation bubble is observed at the bronchi entrance, generating a stronger shear layer and increasing the wall shear stress on the bottom bronchi wall. The differences observed go against the notion that the main airway, i.e. trachea and main bronchi, may be modeled as smooth. Our results suggest that cartilage rings will have an impact on the wall shear stress and may affect particle deposition, which is of importance in inhaled drug delivery and pollutant deposition in the airway. Additionally, the effects introduced by the rings may change the flow characteristics in further generations.

Evolutionary melting pots: a biodiversity hotspot shaped by ring diversifications around the Black Sea in the Eastern tree frog (Hyla orientalis).

PubMed

Dufresnes, Christophe; Litvinchuk, Spartak N; Leuenberger, Julien; Ghali, Karim; Zinenko, Oleksandr; Stöck, Matthias; Perrin, Nicolas

2016-09-01

Hotspots of intraspecific genetic diversity, which are of primary importance for the conservation of species, have been associated with glacial refugia, that is areas where species survived the Quaternary climatic oscillations. However, the proximate mechanisms generating these hotspots remain an open issue. Hotspots may reflect the long-term persistence of large refugial populations; alternatively, they may result from allopatric differentiation between small and isolated populations, that later admixed. Here, we test these two scenarios in a widely distributed species of tree frog, Hyla orientalis, which inhabits Asia Minor and southeastern Europe. We apply a fine-scale phylogeographic survey, combining fast-evolving mitochondrial and nuclear markers, with a dense sampling throughout the range, as well as ecological niche modelling, to understand what shaped the genetic variation of this species. We documented an important diversity centre around the Black Sea, composed of multiple allopatric and/or parapatric diversifications, likely driven by a combination of Pleistocene climatic fluctuations and complex regional topography. Remarkably, this diversification forms a ring around the Black Sea, from the Caucasus through Anatolia and eastern Europe, with terminal forms coming into contact and partially admixing in Crimea. Our results support the view that glacial refugia generate rather than host genetic diversity and can also function as evolutionary melting pots of biodiversity. Moreover, we report a new case of ring diversification, triggered by a large, yet cohesive dispersal barrier, a very rare situation in nature. Finally, we emphasize the Black Sea region as an important centre of intraspecific diversity in the Palearctic with implications for conservation. © 2016 John Wiley & Sons Ltd.

Weeds, as ancillary hosts, pose disproportionate risk for virulent pathogen transfer to crops.

PubMed

Linde, Celeste C; Smith, Leon M; Peakall, Rod

2016-05-12

The outcome of the arms race between hosts and pathogens depends heavily on the interactions between their genetic diversity, population size and transmission ability. Theory predicts that genetically diverse hosts will select for higher virulence and more diverse pathogens than hosts with low genetic diversity. Cultivated hosts typically have lower genetic diversity and thus small effective population sizes, but can potentially harbour large pathogen population sizes. On the other hand, hosts, such as weeds, which are genetically more diverse and thus have larger effective population sizes, usually harbour smaller pathogen population sizes. Large pathogen population sizes may lead to more opportunities for mutation and hence more diverse pathogens. Here we test the predictions that pathogen neutral genetic diversity will increase with large pathogen population sizes and host diversity, whereas diversity under selection will increase with host diversity. We assessed and compared the diversity of a fungal pathogen, Rhynchosporium commune, on weedy barley grass (which have a large effective population size) and cultivated barley (low genetic diversity) using microsatellites, effector locus nip1 diversity and pathogen aggressiveness in order to assess the importance of weeds in the evolution of the neutral and selected diversity of pathogens. The findings indicated that the large barley acreage and low host diversity maintains higher pathogen neutral genetic diversity and lower linkage disequilibrium, while the weed maintains more pathotypes and higher virulence diversity at nip1. Strong evidence for more pathogen migration from barley grass to barley suggests transmission of virulence from barley grass to barley is common. Pathogen census population size is a better predictor for neutral genetic diversity than host diversity. Despite maintaining a smaller pathogen census population size, barley grass acts as an important ancillary host to R. commune, harbouring highly virulent pathogen types capable of transmission to barley. Management of disease on crops must therefore include management of weedy ancillary hosts, which may harbour disproportionate supplies of virulent pathogen strains.

Ring rolling process simulation for geometry optimization

NASA Astrophysics Data System (ADS)

Franchi, Rodolfo; Del Prete, Antonio; Donatiello, Iolanda; Calabrese, Maurizio

2017-10-01

Ring Rolling is a complex hot forming process where different rolls are involved in the production of seamless rings. Since each roll must be independently controlled, different speed laws must be set; usually, in the industrial environment, a milling curve is introduced to monitor the shape of the workpiece during the deformation in order to ensure the correct ring production. In the present paper a ring rolling process has been studied and optimized in order to obtain anular components to be used in aerospace applications. In particular, the influence of process input parameters (feed rate of the mandrel and angular speed of main roll) on geometrical features of the final ring has been evaluated. For this purpose, a three-dimensional finite element model for HRR (Hot Ring Rolling) has been implemented in SFTC DEFORM V11. The FEM model has been used to formulate a proper optimization problem. The optimization procedure has been implemented in the commercial software DS ISight in order to find the combination of process parameters which allows to minimize the percentage error of each obtained dimension with respect to its nominal value. The software allows to find the relationship between input and output parameters applying Response Surface Methodology (RSM), by using the exact values of output parameters in the control points of the design space explored through FEM simulation. Once this relationship is known, the values of the output parameters can be calculated for each combination of the input parameters. After the calculation of the response surfaces for the selected output parameters, an optimization procedure based on Genetic Algorithms has been applied. At the end, the error between each obtained dimension and its nominal value has been minimized. The constraints imposed were the maximum values of standard deviations of the dimensions obtained for the final ring.

The Effects of Forming Parameters on Conical Ring Rolling Process

PubMed Central

Meng, Wen; Zhao, Guoqun; Guan, Yanjin

2014-01-01

The plastic penetration condition and biting-in condition of a radial conical ring rolling process with a closed die structure on the top and bottom of driven roll, simplified as RCRRCDS, were established. The reasonable value range of mandrel feed rate in rolling process was deduced. A coupled thermomechanical 3D FE model of RCRRCDS process was established. The changing laws of equivalent plastic strain (PEEQ) and temperature distributions with rolling time were investigated. The effects of ring's outer radius growth rate and rolls sizes on the uniformities of PEEQ and temperature distributions, average rolling force, and average rolling moment were studied. The results indicate that the PEEQ at the inner layer and outer layer of rolled ring are larger than that at the middle layer of ring; the temperatures at the “obtuse angle zone” of ring's cross-section are higher than those at “acute angle zone”; the temperature at the central part of ring is higher than that at the middle part of ring's outer surfaces. As the ring's outer radius growth rate increases at its reasonable value ranges, the uniformities of PEEQ and temperature distributions increase. Finally, the optimal values of the ring's outer radius growth rate and rolls sizes were obtained. PMID:25202716

Ordered quasi-two-dimensional structure of nanoparticles in semiflexible ring polymer brushes under compression

NASA Astrophysics Data System (ADS)

Hua, Yunfeng; Deng, Zhenyu; Jiang, Yangwei; Zhang, Linxi

2017-06-01

Molecular dynamics simulations of a coarse-grained bead-spring model of ring polymer brushes under compression are presented. Flexible polymer brushes are always disordered during compression, whereas semiflexible polymer brushes tend to be ordered under sufficiently strong compression. Further, the polymer monomer density of the semiflexible polymer brush is very high near the brush surface, inducing a peak value of the free energy near the surface. Therefore, when nanoparticles are compressed in semiflexible ring polymer brushes, they tend to exhibit a closely packed single-layer structure between the brush surface and the impenetrable wall, and a quasi-two-dimensional ordered structure near the brush surface is formed under strong compression. These findings provide a new approach to designing responsive applications.

Cascade conical refraction for annular pumping of a vortex Nd:YAG laser and selective excitation of low- and high-order Laguerre–Gaussian modes

NASA Astrophysics Data System (ADS)

Wu, Yongxiao; Wang, Zhongyang; Chen, Sanbin; Shirakwa, Akira; Ueda, Ken-ichi; Li, Jianlang

2018-05-01

We proposed an efficient and vortex Nd:YAG laser for selective lasing of low- and high-order vortex modes, in which multiple-ring pump light was originated from cascaded conical refraction of multiple biaxial crystals. In our proof of concept demonstration, we used two-crystal cascade conical refraction to generate two-ring pump light; the mutual intensity ratio and relative separation of the inner ring and outer ring were controlled by rotating the second biaxial crystal and by moving the imaging lens, respectively. As a result, we obtained selective excitation of Laguerre–Gaussian (LG01 and LG03) vortex modes in the end-pump Nd:YAG laser. For LG01-mode output, the laser power reached 439 mW with 52.5% slope efficiency; for LG03-mode output, the laser power reached 160 mW with 41.3% slope efficiency. Our results revealed that the multiple-ring pumping technique based on cascaded conical refraction would pave the way for realization of the efficient and switchable excitation of low- and high-order LG modes in an end-pumped solid-state laser.

[Analysis of genetics mechanism for the phenotypic diversity in a patient carrying a rare ring chromosome 9].

PubMed

Qin, Shengfang; Wang, Xueyan; Li, Yunxing; Wei, Ping; Chen, Chun; Zeng, Lan

2016-02-01

To explore the genetics mechanism for the phenotypic variability in a patient carrying a rare ring chromosome 9. The karyotype of the patient was analyzed with cytogenetics method. Presence of sex chromosome was confirmed with fluorescence in situ hybridization. The SRY gene was subjected to PCR amplification and direct sequencing. Potential deletion and duplication were detected with array-based comparative genomic hybridization (array-CGH). The karyotype of the patient has comprised 6 types of cell lines containing a ring chromosome 9. The SRY gene sequence was normal. By array-CGH, the patient has carried a hemizygous deletion at 9p24.3-p23 (174 201-9 721 761) encompassing 30 genes from Online Mendelian Inheritance in Man. The phenotypic variability of the 9p deletion syndrome in conjunct with ring chromosome 9 may be attributable to multiple factors including loss of chromosomal material, insufficient dosage of genes, instability of ring chromosome, and pattern of inheritance.

A properly configured ring structure is critical for the function of the mitochondrial DNA recombination protein, Mgm101.

PubMed

Nardozzi, Jonathan D; Wang, Xiaowen; Mbantenkhu, MacMillan; Wilkens, Stephan; Chen, Xin Jie

2012-10-26

Mgm101 is a Rad52-type recombination protein of bacteriophage origin required for the repair and maintenance of mitochondrial DNA (mtDNA). It forms large oligomeric rings of ∼14-fold symmetry that catalyze the annealing of single-stranded DNAs in vitro. In this study, we investigated the structural elements that contribute to this distinctive higher order structural organization and examined its functional implications. A pair of vicinal cysteines, Cys-216 and Cys-217, was found to be essential for mtDNA maintenance. Mutations to the polar serine, the negatively charged aspartic and glutamic acids, and the hydrophobic amino acid alanine all destabilize mtDNA in vivo. The alanine mutants have an increased propensity of forming macroscopic filaments. In contrast, mutations to aspartic acid drastically destabilize the protein and result in unstructured aggregates with severely reduced DNA binding activity. Interestingly, the serine mutants partially disassemble the Mgm101 rings into smaller oligomers. In the case of the C216S mutant, a moderate increase in DNA binding activity was observed. By using small angle x-ray scattering analysis, we found that Mgm101 forms rings of ∼200 Å diameter in solution, consistent with the structure previously established by transmission electron microscopy. We also found that the C216A/C217A double mutant tends to form broken rings, which likely provide free ends for seeding the growth of the super-stable but functionally defective filaments. Taken together, our data underscore the importance of a delicately maintained ring structure critical for Mgm101 activity. We discuss a potential role of Cys-216 and Cys-217 in regulating Mgm101 function and the repair of damaged mtDNA under stress conditions.

Magnetic field of longitudinal gradient bend

NASA Astrophysics Data System (ADS)

Aiba, Masamitsu; Böge, Michael; Ehrlichman, Michael; Streun, Andreas

2018-06-01

The longitudinal gradient bend is an effective method for reducing the natural emittance in light sources. It is, however, not a common element. We have analyzed its magnetic field and derived a set of formulae. Based on the derivation, we discuss how to model the longitudinal gradient bend in accelerator codes that are used for designing electron storage rings. Strengths of multipole components can also be evaluated from the formulae, and we investigate the impact of higher order multipole components in a very low emittance lattice.

Developing Inclusive Teaching and Learning Through the Principles of Universal Design.

PubMed

Knarlag, Kjetil; Olaussen, Elinor

2016-01-01

For decades, the term reasonable accommodations has been the lead strategy and praxis in addressing diversity and disabilities in Higher Education. Universal Design for Learning (UDL) is a well-known theory and a practical approach which challenges these traditions in order to improve inclusive teaching and learning in the American school system. A European funded project, UDLL, has transferred these theories to a European context, and developed best practice guidelines for key stakeholders in European Higher Education Institutions. This universal approach challenges established traditions, methods and mindsets in addressing the diverse student population.

Are the Dyson rings around pulsars detectable?

NASA Astrophysics Data System (ADS)

Osmanov, Z.

2018-04-01

In the previous paper ring (Osmanov 2016) (henceforth Paper-I) we have extended the idea of Freeman Dyson and have shown that a supercivilization has to use ring-like megastructures around pulsars instead of a spherical shell. In this work we reexamine the same problem in the observational context and we show that facilities of modern infrared (IR) telescopes (Very Large Telescope Interferometer and Wide-field Infrared Survey Explorer (WISE)) might efficiently monitor the nearby zone of the solar system and search for the IR Dyson-rings up to distances of the order of 0.2 kpc, corresponding to the current highest achievable angular resolution, 0.001 mas. In this case the total number of pulsars in the observationally reachable area is about 64 +/- 21. We show that pulsars from the distance of the order of ~ 1 kpc are still visible for WISE as point-like sources but in order to confirm that the object is the neutron star, one has to use the ultraviolet telescopes, which at this moment cannot provide enough sensitivity.

[A comparative study of three types of IUD].

PubMed

Lai, K R; Chen, Q B

1991-11-01

In Zhejiang Province, China, there are 2.7 million IUD users. 90% of them use stainless steel single ring. In order to evaluate the effectiveness of the IUDs, the Provincial Family Planning Commission organized a prospective comparative study on 3 kinds of IUDs: the single ring made in Wuxi, the metal ring with plastic core made in Beijing, and the copper TCU 220c made in Tianjin. Between October 1985 and March 1986 1199 healthy women aged 20-39 who had 2 or fewer normal deliveries and without previous history of ectopic pregnancy were screened and recruited to the study. They were randomly assigned to be inserted with the IUDs. 400 women had single ring, 402 women had metal with plastic core, and 397 had TCu 220c. 8 postinsertion follow-up visits were conducted up to 3 years, and menstruations were recorded every month. During the study, 4 cases were lost to follow-up. In the single-ring group, the cumulative continuation rates at 12, 24, and 36 months were 73.4, 66.7, and 65.7% respectively. For the metal-plastic ring group, it was 80.9, 72.3, and 69.3% and for the TCu 220c group, it was 94.5, 88.4, and 83.1%, respectively. The expulsion rates among the 3 kinds of IUDs were statistically significant at 12, 24, and 36 months. The highest expulsion rates were the single ring and TCu 220c were the lowest. The pregnancy rates were highest among metal-plastic ring users and lowest among TCu 220c users. The differences were not statistically significant between single ring and metal-plastic ring users. Discontinuation due to excessive menstrual bleeding were similar among the 3 methods probably due to treatment of the users who experienced excessive bleeding. Younger women and women who experienced fewer pregnancies were found to have higher expulsion and pregnancy rates. But the occurrence of side effects such as prolonged menstrual periods, spotting, and back pain were highest among TCu 220c users. It was recommended that the more effective TCu 220c should be promoted to replace the single ring. Since different sizes of TCu IUDs have been developed, it would be possible to reduce excessive menstrual bleeding and its side effects.

Anticipating cascading change in forests: Seeking a deeper understanding of the future

Treesearch

David N. Bengston; Mike Dockry; Stephen R. Shifley

2017-01-01

This study used a participatory group brainstorming process called the Futures Wheel to identify and evaluate the direct and higher-order implications of this trend: Central Hardwood forests lack age-class diversity and will uniformly grow old. Five 1st-order consequences of this trend were identified: continued significant decrease in early-successional forest,...

Hot Streak Characterization in Serpentine Exhaust Nozzles

DTIC Science & Technology

2014-12-26

111 4.4 Nozzles Listed in Ascending Order of Modified Dean Number . . . . . . . . . 206 4.5 CDI Results Per Ring ...212 4.6 RDI Results Per Ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 4.7 No-Swirl Surface...non-dimensional stagnation pressure PT2/PT0 non-dimensional freestream total pressure PAV average ring total pressure (Pa) xxi Symbol Definition PAVLOW

Non-Linear Dynamics of Saturn’s Rings

NASA Astrophysics Data System (ADS)

Esposito, Larry W.

2015-11-01

Non-linear processes can explain why Saturn’s rings are so active and dynamic. Ring systems differ from simple linear systems in two significant ways: 1. They are systems of granular material: where particle-to-particle collisions dominate; thus a kinetic, not a fluid description needed. We find that stresses are strikingly inhomogeneous and fluctuations are large compared to equilibrium. 2. They are strongly forced by resonances: which drive a non-linear response, pushing the system across thresholds that lead to persistent states.Some of this non-linearity is captured in a simple Predator-Prey Model: Periodic forcing from the moon causes streamline crowding; This damps the relative velocity, and allows aggregates to grow. About a quarter phase later, the aggregates stir the system to higher relative velocity and the limit cycle repeats each orbit.Summary of Halo Results: A predator-prey model for ring dynamics produces transient structures like ‘straw’ that can explain the halo structure and spectroscopy: This requires energetic collisions (v ≈ 10m/sec, with throw distances about 200km, implying objects of scale R ≈ 20km).Transform to Duffing Eqn : With the coordinate transformation, z = M2/3, the Predator-Prey equations can be combined to form a single second-order differential equation with harmonic resonance forcing.Ring dynamics and history implications: Moon-triggered clumping at perturbed regions in Saturn’s rings creates both high velocity dispersion and large aggregates at these distances, explaining both small and large particles observed there. We calculate the stationary size distribution using a cell-to-cell mapping procedure that converts the phase-plane trajectories to a Markov chain. Approximating the Markov chain as an asymmetric random walk with reflecting boundaries allows us to determine the power law index from results of numerical simulations in the tidal environment surrounding Saturn. Aggregates can explain many dynamic aspects of the rings and can renew rings by shielding and recycling the material within them, depending on how long the mass is sequestered. We can ask: Are Saturn’s rings a chaotic non-linear driven system?

Unstable-type chromosome aberrations in lymphocytes from individuals living near Semipalatinsk nuclear test site.

PubMed

Tanaka, Kimio; Iida, Shozo; Takeichi, Nobuo; Chaizhunusova, Nailya J; Gusev, Boris I; Apsalikov, Kazbek N; Inaba, Toshiya; Hoshi, Masaharu

2006-02-01

The Semipalatinsk nuclear test site area is considered to have been highly contaminated with radioactive fallout during 40 years of continuous nuclear testing. Individuals living near the nuclear test site are considered to have been exposed to both internal and external radiation. In order to assess the effects of prolonged radiation, a chromosome analysis was performed in lymphocytes from 123 people living in three villages, Dolon, Sarjar and Kaynar, and 46 control people in Kokpekty. A micronucleus assay was also conducted in 233 people in six different contaminated villages and one control village. Frequencies of dicentric and ring chromosomes were higher in residents of the contaminated area (1.55-2.56 per 1,000 cells) than those of the non-contaminated area (0.78 per 1,000 cells). Frequencies of dicentric chromosomes with fragments were also higher in the exposed group (0.44-0.96 per 1,000 cells). Among residents of the four villages, the incidence of multiple complex chromosome aberrations (MCA) was 0.03-0.34%. Incidences of micronucleus were also higher in the exposed group (9.36-12.3 per 1,000 lymphocytes) than the non-exposed group (7.25 per 1,000 lymphocytes). The higher incidence of unstable-type aberrations such as dicentric, ring chromosomes and micronuclei found in residents of contaminated areas seems to be mainly caused by internal exposure and other factors.

Operating characteristics of a three-piece-inner-ring large-bore roller bearing to speeds of 3 million DN

NASA Technical Reports Server (NTRS)

Schuller, F. T.

1984-01-01

A 118 mm bore roller bearing with a three piece inner ring ran successfully at 300,000 DN for 20 hr. Provisions were made for lubrication and cooling through the inner ring. In some tests the outer ring was also cooled. Power loss within the bearing increased with both speed and total oil flow rate to the inner ring. Outer ring temperature decreased by as much as 22 K (40 F) when outer ring cooling was employed whereas inner ring temperature remained essentially constant. Cage slip was greatly reduced or even eliminated by using a bearing with a very tight clearance at operating speed. A three piece inner ring bearing had higher inner ring temperatures and less temperature difference between the inner and outer rings than a conventional one piece inner ring bearing.

Olive tree-ring problematic dating: a comparative analysis on Santorini (Greece).

PubMed

Cherubini, Paolo; Humbel, Turi; Beeckman, Hans; Gärtner, Holger; Mannes, David; Pearson, Charlotte; Schoch, Werner; Tognetti, Roberto; Lev-Yadun, Simcha

2013-01-01

Olive trees are a classic component of Mediterranean environments and some of them are known historically to be very old. In order to evaluate the possibility to use olive tree-rings for dendrochronology, we examined by various methods the reliability of olive tree-rings identification. Dendrochronological analyses of olive trees growing on the Aegean island Santorini (Greece) show that the determination of the number of tree-rings is impossible because of intra-annual wood density fluctuations, variability in tree-ring boundary structure, and restriction of its cambial activity to shifting sectors of the circumference, causing the tree-ring sequences along radii of the same cross section to differ.

Initial measurements of O-ion and He-ion decay rates observed from the Van Allen probes RBSPICE instrument

PubMed Central

Gerrard, Andrew; Lanzerotti, Louis; Gkioulidou, Matina; Mitchell, Donald; Manweiler, Jerry; Bortnik, Jacob; Keika, Kunihiro

2014-01-01

H-ion (∼45 keV to ∼600 keV), He-ion (∼65 keV to ∼520 keV), and O-ion (∼140 keV to ∼1130 keV) integral flux measurements, from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft B, are reported. These abundance data form a cohesive picture of ring current ions during the first 9 months of measurements. Furthermore, the data presented herein are used to show injection characteristics via the He-ion/H-ion abundance ratio and the O-ion/H-ion abundance ratio. Of unique interest to ring current dynamics are the spatial-temporal decay characteristics of the two injected populations. We observe that He-ions decay more quickly at lower L shells, on the order of ∼0.8 day at L shells of 3–4, and decay more slowly with higher L shell, on the order of ∼1.7 days at L shells of 5–6. Conversely, O-ions decay very rapidly (∼1.5 h) across all L shells. The He-ion decay time are consistent with previously measured and calculated lifetimes associated with charge exchange. The O-ion decay time is much faster than predicted and is attributed to the inclusion of higher-energy (> 500 keV) O-ions in our decay rate estimation. We note that these measurements demonstrate a compelling need for calculation of high-energy O-ion loss rates, which have not been adequately studied in the literature to date. Key Points We report initial observations of ring current ions We show that He-ion decay rates are consistent with theory We show that O-ions with energies greater than 500 keV decay very rapidly PMID:26167435

Factors Influencing Bacterial Diversity and Community Composition in Municipal Drinking Waters in the Ohio River Basin, USA

PubMed Central

Stanish, Lee F.; Hull, Natalie M.; Robertson, Charles E.; Harris, J. Kirk; Stevens, Mark J.; Spear, John R.; Pace, Norman R.

2016-01-01

The composition and metabolic activities of microbes in drinking water distribution systems can affect water quality and distribution system integrity. In order to understand regional variations in drinking water microbiology in the upper Ohio River watershed, the chemical and microbiological constituents of 17 municipal distribution systems were assessed. While sporadic variations were observed, the microbial diversity was generally dominated by fewer than 10 taxa, and was driven by the amount of disinfectant residual in the water. Overall, Mycobacterium spp. (Actinobacteria), MLE1-12 (phylum Cyanobacteria), Methylobacterium spp., and sphingomonads were the dominant taxa. Shifts in community composition from Alphaproteobacteria and Betaproteobacteria to Firmicutes and Gammaproteobacteria were associated with higher residual chlorine. Alpha- and beta-diversity were higher in systems with higher chlorine loads, which may reflect changes in the ecological processes structuring the communities under different levels of oxidative stress. These results expand the assessment of microbial diversity in municipal distribution systems and demonstrate the value of considering ecological theory to understand the processes controlling microbial makeup. Such understanding may inform the management of municipal drinking water resources. PMID:27362708

Factors Influencing Bacterial Diversity and Community Composition in Municipal Drinking Waters in the Ohio River Basin, USA.

PubMed

Stanish, Lee F; Hull, Natalie M; Robertson, Charles E; Harris, J Kirk; Stevens, Mark J; Spear, John R; Pace, Norman R

2016-01-01

The composition and metabolic activities of microbes in drinking water distribution systems can affect water quality and distribution system integrity. In order to understand regional variations in drinking water microbiology in the upper Ohio River watershed, the chemical and microbiological constituents of 17 municipal distribution systems were assessed. While sporadic variations were observed, the microbial diversity was generally dominated by fewer than 10 taxa, and was driven by the amount of disinfectant residual in the water. Overall, Mycobacterium spp. (Actinobacteria), MLE1-12 (phylum Cyanobacteria), Methylobacterium spp., and sphingomonads were the dominant taxa. Shifts in community composition from Alphaproteobacteria and Betaproteobacteria to Firmicutes and Gammaproteobacteria were associated with higher residual chlorine. Alpha- and beta-diversity were higher in systems with higher chlorine loads, which may reflect changes in the ecological processes structuring the communities under different levels of oxidative stress. These results expand the assessment of microbial diversity in municipal distribution systems and demonstrate the value of considering ecological theory to understand the processes controlling microbial makeup. Such understanding may inform the management of municipal drinking water resources.

Properties of the insertion devices for PETRA III and its extension

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

Schöps, A., E-mail: andreas.schoeps@desy.de; Vagin, P.; Tischer, M., E-mail: markus.tischer@desy.de

DESY presently operates 14 independent insertion device (ID) beamlines at its 6 GeV storage ring PETRA III. Besides the 2 m long standard undulators U29 and U32, several special IDs of up to 5 m length have been installed to meet the experimental requests for high energy X-rays, elliptically polarized light, and a higher degree of coherence. Two additional half octants of the ring have recently been reconstructed, in order to extend the experimental capabilities at PETRA III. The straight sections also allow for installation of IDs of 2 m or 5 m length. This article gives an overview ofmore » the ID key parameters, the spectral properties and the brilliance of the current undulators installed at PETRA III. It also presents the characteristics of some of the upcoming special IDs, like in-vacuum and short undulators.« less

The Muon g-2 Experiment overview and status as of June 2016

DOE PAGES

Holzbauer, J. L.

2016-12-09

The Muon g-2 Experiment at Fermilab will measure the anomalous magnetic moment of the muon to a precision of 140 parts per billion, which is a factor of four improvement over the previous E821 measurement at Brookhaven. The experiment will also extend the search for the electric dipole moment (EDM) of the muon by approximately two orders of magnitude, with a sensitivity down to 10 -21 e.cm. Both of these measurements are made by combining a precise measurement of the 1.45T storage ring magnetic field with an analysis of the modulation of the decay rate of higher-energy positrons (from anti-muons),more » recorded by 24 calorimeters and 3 straw tracking detectors. Furthermore, the recent progress in the alignment of the electrostatic quadrapole plates and the trolley rails inside the vacuum chambers, and in establishing the uniform storage ring magnetic field will be described.« less

13C CP MAS NMR and GIAO-CHF/DFT calculations of flavonoids: Morin, kaempferol, tricin, genistein, formononetin and 3,7-dihydroxyflavone

NASA Astrophysics Data System (ADS)

Zielińska, Agnieszka; Paradowska, Katarzyna; Jakowski, Jacek; Wawer, Iwona

2008-02-01

13C CP MAS NMR spectra of the flavonoids: morin, kaempferol, 3,7-dihydroxyflavone, tricin and isoflavones: genistein and formononetin were recorded to characterize solid-state conformations. Intramolecular hydrogen bonds forming five-, six- and seven-membered rings are present in the two morin molecules in the crystals - their 13C resonances have been assigned with the aid of the calculated shielding constants. Linear relationships between the calculated shielding constants σDFT (ppm) and chemical shifts ( δCPMAS, ppm) were obtained for all studied compounds. Higher correlation coefficients suggest that the conformation with "clockwise" orientation of both OH groups is more probable in the solid 3,7-dihydroxyflavone, whereas in the solid formononetin the OH and OCH 3 substituents are directed "anticlockwise". The barrier to the rotation of phenyl ring B decreases in the order: morin (2'-OH, 3-OH) > kaempferol (3-OH) > tricin.

The Muon g-2 Experiment Overview and Status as of June 2016

NASA Astrophysics Data System (ADS)

Holzbauer, J.

2016-11-01

The Muon g-2 Experiment at Fermilab will measure the anomalous magnetic moment of the muon to a precision of 140 parts per billion, which is a factor of four improvement over the previous E821 measurement at Brookhaven. The experiment will also extend the search for the electric dipole moment (EDM) of the muon by approximately two orders of magnitude, with a sensitivity down to 10-21 e.cm. Both of these measurements are made by combining a precise measurement of the 1.45T storage ring magnetic field with an analysis of the modulation of the decay rate of higher-energy positrons (from anti-muons), recorded by 24 calorimeters and 3 straw tracking detectors. The recent progress in the alignment of the electrostatic quadrapole plates and the trolley rails inside the vacuum chambers, and in establishing the uniform storage ring magnetic field will be described.

Colombian Creole horse breeds: Same origin but different diversity

PubMed Central

Jimenez, Ligia Mercedes; Mendez, Susy; Dunner, Susana; Cañón, Javier; Cortés, Óscar

2012-01-01

In order to understand the genetic ancestry and mitochondrial DNA (mtDNA) diversity of current Colombian horse breeds we sequenced a 364-bp fragment of the mitocondrial DNA D-loop in 116 animals belonging to five Spanish horse breeds and the Colombian Paso Fino and Colombian Creole cattle horse breeds. Among Colombian horse breeds, haplogroup D had the highest frequency (53%), followed by haplogroups A (19%), C (8%) and F (6%). The higher frequency of haplogroup D in Colombian horse breeds supports the theory of an ancestral Iberian origin for these breeds. These results also indicate that different selective pressures among the Colombian breeds could explain the relatively higher genetic diversity found in the Colombian Creole cattle horse when compared with the Colombian Paso Fino. PMID:23271940

Comparison of combined hormonal vaginal ring and low dose combined oral hormonal pill for the treatment of idiopathic chronic pelvic pain: a randomised trial.

PubMed

Priya, Khushboo; Rajaram, Shalini; Goel, Neerja

2016-12-01

To compare the efficacy and acceptability of combined hormonal vaginal ring with combined oral hormonal pill in women with idiopathic chronic pelvic pain. Randomised prospective interventional trial conducted in 60 women with idiopathic chronic pelvic pain. Women were randomised into two groups of 30 each. In each group, treatment was given for 84 days using either combined vaginal ring or combined oral hormonal pill. Hormonal vaginal ring releases 15mcg of ethinyl estradiol and 120mcg of the etonogestrel per day while the hormonal pill contained 30mcg of ethinyl estradiol and 150mcg of levonorgestrel. There was no ring or pill free week. After every 28 days, pain relief was measured using visual analogue scale (VAS), and verbal rating score (VRS) calculated by summing dysmenorrhea, non-cyclic pelvic pain (NCCP) and deep dyspareunia scores. Side effects, compliance, satisfaction, and user acceptability were also measured. Data was analyzed using various parametric and non-parametric tests. Reduction in mean VAS score at end of treatment in ring group was 6.23 (95% confidence interval [CI], 5.45-7.01; p<0.001) as compared to 5.53 in pill group (95% CI, 4.83-6.23; p<0.001). Reduction in mean VRS score was 5.63 in ring users (95% CI, 4.84-6.42; p<0.001) versus 4.36 in pill users (95% CI, 3.63-5.10; p<0.001). A significantly higher persistent relief in NCPP score was observed in vaginal ring group as compared to oral pill group at end of one month after stopping treatment. Compliance, satisfaction, and user acceptability were higher in ring users (80%) than pill users (70%) and a higher incidence of nausea was seen in pill group. Present study demonstrates for first time that both vaginal and oral hormonal therapy are effective in treatment of idiopathic chronic pelvic pain and vaginal ring may be a better choice with higher satisfaction rate and fewer side effects. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

5.7  W cw single-frequency laser at 671  nm by single-pass second harmonic generation of a 17.2  W injection-locked 1342  nm Nd : YVO4 ring laser using periodically poled MgO : LiNbO3.

PubMed

Koch, Peter; Ruebel, Felix; Bartschke, Juergen; L'huillier, Johannes A

2015-11-20

We demonstrate a continuous wave single-frequency laser at 671.1 nm based on a high-power 888 nm pumped Nd:YVO4 ring laser at 1342.2 nm. Unidirectional operation of the fundamental ring laser is achieved with the injection-locking technique. A Nd:YVO4 microchip laser serves as the injecting seed source, providing a tunable single-frequency power of up to 40 mW. The ring laser emits a single-frequency power of 17.2 W with a Gaussian beam profile and a beam propagation factor of M2<1.1. A 60-mm-long periodically poled MgO-doped LiNbO3 crystal is used to generate the second harmonic in a single-pass scheme. Up to 5.7 W at 671.1 nm with a Gaussian shaped beam profile and a beam propagation factor of M2<1.2 are obtained, which is approximately twice the power of previously reported lasers. This work opens possibilities in cold atoms experiments with lithium, allowing the use of larger ensembles in magneto-optical traps or higher diffraction orders in atomic beam interferometers.

Orbital-angular-momentum mode-group multiplexed transmission over a graded-index ring-core fiber based on receive diversity and maximal ratio combining

NASA Astrophysics Data System (ADS)

Zhang, Junwei; Zhu, Guoxuan; Liu, Jie; Wu, Xiong; Zhu, Jiangbo; Du, Cheng; Luo, Wenyong; Chen, Yujie; Yu, Siyuan

2018-02-01

An orbital-angular-momentum (OAM) mode-group multiplexing (MGM) scheme based on a graded-index ring-core fiber (GIRCF) is proposed, in which a single-input two-output (or receive diversity) architecture is designed for each MG channel and simple digital signal processing (DSP) is utilized to adaptively resist the mode partition noise resulting from random intra-group mode crosstalk. There is no need of complex multiple-input multiple-output (MIMO) equalization in this scheme. Furthermore, the signal-to-noise ratio (SNR) of the received signals can be improved if a simple maximal ratio combining (MRC) technique is employed on the receiver side to efficiently take advantage of the diversity gain of receiver. Intensity-modulated direct-detection (IM-DD) systems transmitting three OAM mode groups with total 100-Gb/s discrete multi-tone (DMT) signals over a 1-km GIRCF and two OAM mode groups with total 40-Gb/s DMT signals over an 18-km GIRCF are experimentally demonstrated, respectively, to confirm the feasibility of our proposed OAM-MGM scheme.

Diversity and distribution of actinobacterial aromatic ring oxygenase genes across contrasting soil properties.

PubMed

Weidow, Christopher A; Bae, Hee-Sung; Chauhan, Ashvini; Ogram, Andrew

2015-04-01

The diversity of a gene family encoding Actinobacterial aromatic ring oxygenases (AAROs) was detected by the PCR-cloning approach using a newly designed PCR primer set. The distribution of AAROs was investigated in 11 soils representing different land management and vegetation zones and was correlated with several geochemical parameters including pH, organic matter (OM), total Kjeldahl nitrogen (TKN), and nitrogen oxides (NO(x)-N: mostly NO3(-)-N). The distribution of individual clades encoding enzymes with potentially different substrates were correlated with different environmental factors, suggesting differential environmental controls on the distribution of specific enzymes as well as sequence diversity. For example, individual clades associated with phthalate dioxygenases were either strongly negatively correlated with pH, or not correlated with pH but showed strong positive correlation with organic carbon content. A large number of clones clustering in a clade related to PAH oxygenases were positively correlated with pH and nitrogen, but not with organic matter. This analysis may yield insight into the ecological forces driving the distribution of these catabolic genes.

Topology of polymer chains under nanoscale confinement.

PubMed

Satarifard, Vahid; Heidari, Maziar; Mashaghi, Samaneh; Tans, Sander J; Ejtehadi, Mohammad Reza; Mashaghi, Alireza

2017-08-24

Spatial confinement limits the conformational space accessible to biomolecules but the implications for bimolecular topology are not yet known. Folded linear biopolymers can be seen as molecular circuits formed by intramolecular contacts. The pairwise arrangement of intra-chain contacts can be categorized as parallel, series or cross, and has been identified as a topological property. Using molecular dynamics simulations, we determine the contact order distributions and topological circuits of short semi-flexible linear and ring polymer chains with a persistence length of l p under a spherical confinement of radius R c . At low values of l p /R c , the entropy of the linear chain leads to the formation of independent contacts along the chain and accordingly, increases the fraction of series topology with respect to other topologies. However, at high l p /R c , the fraction of cross and parallel topologies are enhanced in the chain topological circuits with cross becoming predominant. At an intermediate confining regime, we identify a critical value of l p /R c , at which all topological states have equal probability. Confinement thus equalizes the probability of more complex cross and parallel topologies to the level of the more simple, non-cooperative series topology. Moreover, our topology analysis reveals distinct behaviours for ring- and linear polymers under weak confinement; however, we find no difference between ring- and linear polymers under strong confinement. Under weak confinement, ring polymers adopt parallel and series topologies with equal likelihood, while linear polymers show a higher tendency for series arrangement. The radial distribution analysis of the topology reveals a non-uniform effect of confinement on the topology of polymer chains, thereby imposing more pronounced effects on the core region than on the confinement surface. Additionally, our results reveal that over a wide range of confining radii, loops arranged in parallel and cross topologies have nearly the same contact orders. Such degeneracy implies that the kinetics and transition rates between the topological states cannot be solely explained by contact order. We expect these findings to be of general importance in understanding chaperone assisted protein folding, chromosome architecture, and the evolution of molecular folds.

Ring current electron dynamics during geomagnetic storms based on the Van Allen Probes measurements: Ring Current Electrons

DOE PAGES

Zhao, H.; Li, X.; Baker, D. N.; ...

2016-04-16

Based on comprehensive measurements from Helium, Oxygen, Proton, and Electron Mass Spectrometer Ion Spectrometer, Relativistic Electron-Proton Telescope, and Radiation Belt Storm Probes Ion Composition Experiment instruments on the Van Allen Probes, comparative studies of ring current electrons and ions are performed and the role of energetic electrons in the ring current dynamics is investigated. The deep injections of tens to hundreds of keV electrons and tens of keV protons into the inner magnetosphere occur frequently; after the injections the electrons decay slowly in the inner belt but protons in the low L region decay very fast. Intriguing similarities between lowermore » energy protons and higher-energy electrons are also found. The evolution of ring current electron and ion energy densities and energy content are examined in detail during two geomagnetic storms, one moderate and one intense. Here, the results show that the contribution of ring current electrons to the ring current energy content is much smaller than that of ring current ions (up to ~12% for the moderate storm and ~7% for the intense storm), and <35 keV electrons dominate the ring current electron energy content at the storm main phases. Though the electron energy content is usually much smaller than that of ions, the enhancement of ring current electron energy content during the moderate storm can get to ~30% of that of ring current ions, indicating a more dynamic feature of ring current electrons and important role of electrons in the ring current buildup. Lastly, the ring current electron energy density is also shown to be higher at midnight and dawn while lower at noon and dusk.« less

Detection and direction discrimination of single vortex rings by harbour seals (Phoca vitulina).

PubMed

Krüger, Yvonne; Hanke, Wolf; Miersch, Lars; Dehnhardt, Guido

2018-04-25

Harbour seals possess highly sensitive vibrissae that enable them to track hydrodynamic trails left behind by a swimming fish. Most of these trails contain vortex rings as a main hydrodynamic component. They may reveal information about their generator as the trails differ depending on the fish species, the fish's body shape, size and swimming style. In addition, fish generate single vortex rings in diverse natural situations. In this study, the ability of blindfolded stationary harbour seals to detect and analyse single vortex rings regarding directional information has been investigated. In three different behavioural experiments, the animals were trained to respond to single artificially generated vortex rings. The results show that harbour seals are able to respond to a variety of different vortex rings upon vibrissal stimulation. The investigation of the minimum hydrodynamically perceivable angle revealed that it is at least as small as 5.7 deg, which was the smallest adjustable angle. Moreover, harbour seals are capable of analysing the travel direction of a vortex ring perceived by the mystacial vibrissae irrespective of whether the vibrissae were stimulated ipsilaterally or contralaterally. In situations in which no complex hydrodynamic trail is available, it is advantageous for a hunting seal to be able to extract information from a single vortex ring. © 2018. Published by The Company of Biologists Ltd.

Cutaneous amelanotic signet-ring cell malignant melanoma with interspersed myofibroblastic differentiation in a young cat.

PubMed

Hirz, Manuela; Herden, Christiane

2016-07-01

The diagnosis of malignant melanoma can be difficult because these tumors can be amelanotic and may contain diverse variants and divergent differentiations, of which the signet-ring cell subtype is very rare and has only been described in humans, dogs, cats, and a hamster. We describe herein histopathologic and immunohistochemical approaches taken to diagnose a case of signet-ring cell malignant melanoma with myofibroblastic differentiation in a cat. A tumor within the abdominal skin of a 2-year-old cat was composed of signet-ring cells and irregularly interwoven streams of spindle cells. Both neoplastic cell types were periodic-acid-Schiff, Fontana, and Sudan black B negative. Signet-ring cells strongly expressed vimentin and S100 protein. Spindle cells strongly expressed vimentin and smooth muscle actin; some cells expressed S100, moderately neuron-specific enolase, and others variably actin and desmin. A few round cells expressed melan A, and a few plump spindle cells expressed melan A and PNL2, confirming the diagnosis of amelanotic signet-ring cell malignant melanoma with myofibroblastic differentiation in a cat. Differential diagnoses were excluded, including signet-ring cell forms of adenocarcinomas, lymphomas, liposarcomas, leiomyosarcomas, squamous cell carcinomas, basal cell carcinomas, and adnexal tumors. © 2016 The Author(s).

The GINGER project and status of the GINGERino prototype at LNGS

NASA Astrophysics Data System (ADS)

Ortolan, A.; Belfi, J.; Bosi, F.; Di Virgilio, A.; Beverini, N.; Carelli, G.; Maccioni, E.; Santagata, R.; Simonelli, A.; Beghi, A.; Cuccato, D.; Donazzan, A.; Naletto, G.

2016-05-01

GINGER (Gyroscopes IN GEneral Relativity) is a proposal for measuring in a ground-based laboratory the Lense-Thirring effect, known also as inertial frame dragging, that is predicted by General Relativity, and is induced by the rotation of a massive source. GINGER will consist in an array of at least three square ring lasers, mutually orthogonal, with about 6-10 m side, and located in a deep underground site, possibly the INFN - National Laboratories of Gran Sasso. The tri-axial design will provide a complete estimation of the laboratory frame angular velocity, to be compared with the Earths rotation estimate provided by IERS with respect the fixed stars frame. Large-size ring lasers have already reached a very high sensitivity, allowing for relevant geodetic measurements. The accuracy required for Lense-Thirring effect measurement is higher than 10-14 rad/s and therefore Earth angular velocity must be measured within one part in 10-9. A 3.6 m side, square ring laser, called GINGERino, has been recently installed inside the Gran Sasso underground laboratories in order to qualify the site for a future installation of GINGER. We discuss the current status of the experimental work, and in particular of the GINGERino prototype.

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

Zhao, H.; Li, X.; Baker, D. N.

Based on comprehensive measurements from Helium, Oxygen, Proton, and Electron Mass Spectrometer Ion Spectrometer, Relativistic Electron-Proton Telescope, and Radiation Belt Storm Probes Ion Composition Experiment instruments on the Van Allen Probes, comparative studies of ring current electrons and ions are performed and the role of energetic electrons in the ring current dynamics is investigated. The deep injections of tens to hundreds of keV electrons and tens of keV protons into the inner magnetosphere occur frequently; after the injections the electrons decay slowly in the inner belt but protons in the low L region decay very fast. Intriguing similarities between lowermore » energy protons and higher-energy electrons are also found. The evolution of ring current electron and ion energy densities and energy content are examined in detail during two geomagnetic storms, one moderate and one intense. Here, the results show that the contribution of ring current electrons to the ring current energy content is much smaller than that of ring current ions (up to ~12% for the moderate storm and ~7% for the intense storm), and <35 keV electrons dominate the ring current electron energy content at the storm main phases. Though the electron energy content is usually much smaller than that of ions, the enhancement of ring current electron energy content during the moderate storm can get to ~30% of that of ring current ions, indicating a more dynamic feature of ring current electrons and important role of electrons in the ring current buildup. Lastly, the ring current electron energy density is also shown to be higher at midnight and dawn while lower at noon and dusk.« less

Effect of a strong-current ion ring on spheromak stability

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

Litwin, C.; Sudan, R.N.

The stability of a spheromak with an energetic ion ring, carrying a current comparable to the plasma current, to the tilt mode is considered. For small departures from sphericity a perturbative approach is applied to an appropriate energy principle in order to calculate the lowest nontrivial kinetic contribution of the ion ring. An analytic stability criterion is obtained. It is seen that the prolate configuration becomes more stable while the oblate one is less stable than in the absence of the ring. The prolomak becomes stable when the ring kinetic energy exceeds the magnetic energy within the separatrix.

Ring distributions leading to species formation: a global topographic analysis of geographic barriers associated with ring species

PubMed Central

2012-01-01

Background In the mid 20th century, Ernst Mayr and Theodosius Dobzhansky championed the significance of circular overlaps or ring species as the perfect demonstration of speciation, yet in the over 50 years since, only a handful of such taxa are known. We developed a topographic model to evaluate whether the geographic barriers that favor processes leading to ring species are common or rare, and to predict where other candidate ring barriers might be found. Results Of the 952,147 geographic barriers identified on the planet, only about 1% are topographically similar to barriers associated with known ring taxa, with most of the likely candidates occurring in under-studied parts of the world (for example, marine environments, tropical latitudes). Predicted barriers separate into two distinct categories: (i) single cohesive barriers (< 50,000 km2), associated with taxa that differentiate at smaller spatial scales (salamander: Ensatina eschscholtzii; tree: Acacia karroo); and (ii) composite barriers - formed by groups of barriers (each 184,000 to 1.7 million km2) in close geographic proximity (totaling 1.9 to 2.3 million km2) - associated with taxa that differentiate at larger spatial scales (birds: Phylloscopus trochiloides and Larus (sp. argentatus and fuscus)). When evaluated globally, we find a large number of cohesive barriers that are topographically similar to those associated with known ring taxa. Yet, compared to cohesive barriers, an order of magnitude fewer composite barriers are similar to those that favor ring divergence in species with higher dispersal. Conclusions While these findings confirm that the topographic conditions that favor evolutionary processes leading to ring speciation are, in fact, rare, they also suggest that many understudied natural systems could provide valuable demonstrations of continuous divergence towards the formation of new species. Distinct advantages of the model are that it (i) requires no a priori information on the relative importance of features that define barriers, (ii) can be replicated using any kind of continuously distributed environmental variable, and (iii) generates spatially explicit hypotheses of geographic species formation. The methods developed here - combined with study of the geographical ecology and genetics of taxa in their environments - should enable recognition of ring species phenomena throughout the world. PMID:22410314

Three-dimensional ordering of cold ion beams in a storage ring: A molecular-dynamics simulation study

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

Yuri, Yosuke, E-mail: yuri.yosuke@jaea.go.jp

Three-dimensional (3D) ordering of a charged-particle beams circulating in a storage ring is systematically studied with a molecular-dynamics simulation code. An ion beam can exhibit a 3D ordered configuration at ultralow temperature as a result of powerful 3D laser cooling. Various unique characteristics of the ordered beams, different from those of crystalline beams, are revealed in detail, such as the single-particle motion in the transverse and longitudinal directions, and the dependence of the tune depression and the Coulomb coupling constant on the operating points.

3-aminopyridazine derivatives with atypical antidepressant, serotonergic, and dopaminergic activities.

PubMed

Wermuth, C G; Schlewer, G; Bourguignon, J J; Maghioros, G; Bouchet, M J; Moire, C; Kan, J P; Worms, P; Biziere, K

1989-03-01

Minaprine [3-[(beta-morpholinoethyl)amino]-4-methyl-6-phenylpyridazine dihydrochloride] is active in most animal models of depression and exhibits in vivo a dual dopaminomimetic and serotoninomimetic activity profile. In an attempt to dissociate these two effects and to characterize the responsible structural requirements, a series of 47 diversely substituted analogues of minaprine were synthesized and tested for their potential antidepressant, serotonergic, and dopaminergic activities. The structure-activity relationships show that dopaminergic and serotonergic activities can be dissociated. Serotonergic activity appears to be correlated mainly with the substituent in the 4-position of the pyridazine ring whereas the dopaminergic activity appears to be dependent on the presence, or in the formation, of a para-hydroxylated aryl ring in the 6-position of the pyridazine ring.

Competing Liquid Phase Instabilities during Pulsed Laser Induced Self-Assembly of Copper Rings into Ordered Nanoparticle Arrays on SiO 2

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

Wu, Y.; Fowlkes, J. D.; Roberts, N. A.

Nanoscale copper rings of different radii, thicknesses, and widths were synthesized on silicon dioxide thin films and were subsequently liquefied via a nanosecond pulse laser treatment. During the nanoscale liquid lifetimes, the rings experience competing retraction dynamics and thin film and/or Rayleigh-Plateau types of instabilities, which lead to arrays of ordered nanodroplets. Surprisingly, the results are significantly different from those of similar experiments carried out on a Si surface.(1) We use hydrodynamic simulations to elucidate how the different liquid/solid interactions control the different instability mechanisms in the present problem.

Linear photonic frequency discriminator on As₂S₃-ring-on-Ti:LiNbO₃ hybrid platform.

PubMed

Kim, Jaehyun; Sung, Won Ju; Eknoyan, Ohannes; Madsen, Christi K

2013-10-21

We report a photonic frequency discriminator built on the vertically integrated As₂S₃-ring-on-Ti:LiNbO₃ hybrid platform. The discriminator consists of a Mach Zehnder interferometer (MZI) formed by the optical path length difference (OPD) between polarization modes of Ti-diffused waveguide on LiNbO₃ substrate and a vertically integrated As₂S₃ race-track ring resonator on top of the substrate. The figures of merit of the device, enhancement of the signal-to-3rd order intermodulation distortion (IMD3) power ratio and corresponding 3rd order intercept point (IP3) over a traditional MZI, are demonstrated through device characterization.

Olive Tree-Ring Problematic Dating: A Comparative Analysis on Santorini (Greece)

PubMed Central

Cherubini, Paolo; Humbel, Turi; Beeckman, Hans; Gärtner, Holger; Mannes, David; Pearson, Charlotte; Schoch, Werner; Tognetti, Roberto; Lev-Yadun, Simcha

2013-01-01

Olive trees are a classic component of Mediterranean environments and some of them are known historically to be very old. In order to evaluate the possibility to use olive tree-rings for dendrochronology, we examined by various methods the reliability of olive tree-rings identification. Dendrochronological analyses of olive trees growing on the Aegean island Santorini (Greece) show that the determination of the number of tree-rings is impossible because of intra-annual wood density fluctuations, variability in tree-ring boundary structure, and restriction of its cambial activity to shifting sectors of the circumference, causing the tree-ring sequences along radii of the same cross section to differ. PMID:23382949

[Influence of different types of surface on the diversity of soil fauna in Beijing Olympic Park].

PubMed

Song, Ying-shi; Li, Xiao-wen; Li, Feng; Li, Hai-mei

2015-04-01

Soil fauna are impacted by urbanization. In order to explore the stress of different surface covers on diversity and community structure of soil fauna, we conducted this experiment in Beijing Olympic Park. In autumn of 2013, we used Baermann and Tullgren methods to study the diversity of soil fauna in the depth of 0-5 cm, 5-10 cm, 10-15 cm under four different land covers i.e. bared field (BF), totally impervious surface (TIS), partly impervious surface (PIS) and grassland (GL). The results showed that the total number of soil fauna in 100 cm3 was in order of GL (210) > PIS (193) > TIS (183) > BF (90), and the number of nematodes accounted for 72.0%-92.8% of the total number. On the vertical level, except for the TIS, the other three types of surface soil fauna had the surface gathered phenomenon. The Shannon diversity index and the Pielou evenness index of BF were lower, but the Simpson dominance index was higher than in the other land covers. The Shannon index and Margalef richness indes of GL were higher than those of the other land covers. The Shannon indexes of TIS and PIS were between the BF and GL. Except for the TIS and GL, the similarity indexes were between 0.4-0.5, indicating moderate non-similar characteristics. The diversity of soil fauna was significantly correlated with temperature, pH and available potassium.

The variations in eccentricity and apse precession rate of a narrow ring perturbed by a close satellite

NASA Technical Reports Server (NTRS)

Borderies, N.; Goldreich, P.; Tremaine, S.

1983-01-01

The first-order perturbations of orbital eccentricity and apse precession rate for the case of a narrow ring, due to a close satellite whose orbit is also eccentric, are described by means of a Hamiltonian. The present treatment covers cases in which the satellite crosses the ring, and the level curves of the Hamiltonian are displayed for several parameter values. The results obtained are applied to the interaction of Saturn's F ring with its inner shepherd satellite.

The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

DOE PAGES

Zhao, H.; Li, X.; Baker, D. N.; ...

2015-08-25

Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute moremore » significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O + is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O +. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. In conclusion, the results show that the measured ring current ions contribute about half of the Dst depression.« less

The evolution of ring current ion energy density and energy content during geomagnetic storms based on Van Allen Probes measurements

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

Zhao, H.; Li, X.; Baker, D. N.

Enabled by the comprehensive measurements from the Magnetic Electron Ion Spectrometer (MagEIS), Helium Oxygen Proton Electron mass spectrometer (HOPE), and Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of ions with different energies and species to the ring current energy density and their dependence on the phases of geomagnetic storms are quantified. The results show that lower energy (<50 keV) protons enhance much more often and also decay much faster than higher-energy protons. During the storm main phase, ions with energies <50 keV contribute moremore » significantly to the ring current than those with higher energies; while the higher-energy protons dominate during the recovery phase and quiet times. The enhancements of higher-energy proton fluxes as well as energy content generally occur later than those of lower energy protons, which could be due to the inward radial diffusion. For the 29 March 2013 storm we investigated in detail that the contribution from O + is ~25% of the ring current energy content during the main phase and the majority of that comes from <50 keV O +. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions. Using the Dessler-Parker-Sckopke relation, the contributions of ring current particles to the magnetic field depression during this geomagnetic storm are also calculated. In conclusion, the results show that the measured ring current ions contribute about half of the Dst depression.« less

DC-Powered Jumping Ring

NASA Astrophysics Data System (ADS)

Jeffery, Rondo N.; Amiri, Farhang

2016-02-01

The classroom jumping ring demonstration is nearly always performed using alternating current (AC), in which the ring jumps or flies off the extended iron core when the switch is closed. The ring jumps higher when cooled with liquid nitrogen (LN2). We have performed experiments using DC to power the solenoid and find similarities and significant differences from the AC case. In particular, the ring does not fly off the core but rises a short distance and then falls back. If the ring jumps high enough, the rising and the falling motion of the ring does not follow simple vertical motion of a projectile. This indicates that there are additional forces on the ring in each part of its motion. Four possible stages of the motion of the ring with DC are identified, which result from the ring current changing directions during the jump in response to a changing magnetic flux through the moving ring.

Functional diversity of 2-oxoglutarate/Fe(II)-dependent dioxygenases in plant metabolism

PubMed Central

Farrow, Scott C.; Facchini, Peter J.

2014-01-01

Oxidative enzymes catalyze many different reactions in plant metabolism. Among this suite of enzymes are the 2-oxoglutarate/Fe(II)-dependent dioxygenases (2-ODDs). Cytochromes P450 (CYPs) as often considered the most versatile oxidative enzymes in nature, but the diversity and complexity of reactions catalyzed by 2-ODDs is superior to the CYPs. The list of oxidative reactions catalyzed by 2-ODDs includes hydroxylations, demethylations, desaturations, ring closure, ring cleavage, epimerization, rearrangement, halogenation, and demethylenation. Furthermore, recent work, including the discovery of 2-ODDs involved in epigenetic regulation, and others catalyzing several characteristic steps in specialized metabolic pathways, support the argument that 2-ODDs are among the most versatile and important oxidizing biological catalysts. In this review, we survey and summarize the pertinent literature with a focus on several key reactions catalyzed by 2-ODDs, and discuss the significance and impact of these enzymes in plant metabolism. PMID:25346740

The narrow rings of Jupiter, Saturn and Uranus

NASA Technical Reports Server (NTRS)

Dermott, S. F.; Murray, C. D.; Sinclair, A. T.

1980-01-01

The origin of the newly discovered narrow ring systems around Jupiter, Saturn and Uranus is considered. It is pointed out that both the Uranian and Jovian ring systems have mean orbital radii of 1.8 planetary radii and lie within the Roche zones of their respective planets, and it is suggested that the Jovian ring is the product of the disintegration of a satellite that entered the Roche zone, and that large numbers of small particles are now in horseshoe orbits about the Lagrangian equilibrium points of the remnant chunks. Analysis of the path of a ring particle in a horseshoe orbit is shown to result in ring structures in agreement with those observed for the circular rings of Jupiter and the highly eccentric ring of Uranus. The stability of these ring systems is then considered, and it is suggested that the F ring of Saturn, which lies outside the Roche zone, represents primordial matter not yet accreted by small satellites just inside the Mimas first-order resonances.

A node organization in the actomyosin contractile ring generates tension and aids stability

PubMed Central

Thiyagarajan, Sathish; Wang, Shuyuan; O’Shaughnessy, Ben

2017-01-01

During cytokinesis, a contractile actomyosin ring constricts and divides the cell in two. How the ring marshals actomyosin forces to generate tension is not settled. Recently, a superresolution microscopy study of the fission yeast ring revealed that myosins and formins that nucleate actin filaments colocalize in plasma membrane-anchored complexes called nodes in the constricting ring. The nodes move bidirectionally around the ring. Here we construct and analyze a coarse-grained mathematical model of the fission yeast ring to explore essential consequences of the recently discovered ring ultrastructure. The model reproduces experimentally measured values of ring tension, explains why nodes move bidirectionally, and shows that tension is generated by myosin pulling on barbed-end-anchored actin filaments in a stochastic sliding-filament mechanism. This mechanism is not based on an ordered sarcomeric organization. We show that the ring is vulnerable to intrinsic contractile instabilities, and protection from these instabilities and organizational homeostasis require both component turnover and anchoring of components to the plasma membrane. PMID:28954859

Formation of lunar basin rings

USGS Publications Warehouse

Hodges, C.A.; Wilhelms, D.E.

1978-01-01

The origin of the multiple concentric rings that characterize lunar impact basins, and the probable depth and diameter of the transient crater have been widely debated. As an alternative to prevailing "megaterrace" hypotheses, we propose that the outer scarps or mountain rings that delineate the topographic rims of basins-the Cordilleran at Orientale, the Apennine at Imbrium, and the Altai at Nectaris-define the transient cavities, enlarged relatively little by slumping, and thus are analogous to the rim crests of craters like Copernicus; inner rings are uplifted rims of craters nested within the transient cavity. The magnitude of slumping that occurs on all scarps is insufficient to produce major inner rings from the outer. These conclusions are based largely on the observed gradational sequence in lunar central uplifts:. from simple peaks through somewhat annular clusters of peaks, peak and ring combinations and double ring basins, culminating in multiring structures that may also include peaks. In contrast, belts of slump terraces are not gradational with inner rings. Terrestrial analogs suggest two possible mechanisms for producing rings. In some cases, peaks may expand into rings as material is ejected from their cores, as apparently occurred at Gosses Bluff, Australia. A second process, differential excavation of lithologically diverse layers, has produced nested experimental craters and is, we suspect, instrumental in the formation of terrestrial ringed impact craters. Peak expansion could produce double-ring structures in homogeneous materials, but differential excavation is probably required to produce multiring and peak-in-ring configurations in large lunar impact structures. Our interpretation of the representative lunar multiring basin Orientale is consistent with formation of three rings in three layers detected seismically in part of the Moon-the Cordillera (basin-bounding) ring in the upper crust, the composite Montes Rook ring in the underlying, more coherent "heald" crust, and an innermost, 320-km ring at the crust-mantle interface. Depth-diameter ratios of 1 10to 1 15 are consistent with this interpretation and suggest that volumes of transient cavities and hence of basin ejecta may be considerably greater than commonly assumed. ?? 1978.

Quantum mechanical design of efficient second-order nonlinear optical materials based on heteroaromatic imido-substituted hexamolybdates: first theoretical framework of POM-based heterocyclic aromatic rings.

PubMed

Janjua, Muhammad Ramzan Saeed Ashraf

2012-11-05

This work was inspired by a previous report (Janjua et al. J. Phys. Chem. A 2009, 113, 3576-3587) in which the nonlinear-optical (NLO) response strikingly improved with an increase in the conjugation path of the ligand and the nature of hexamolybdates (polyoxometalates, POMs) was changed into a donor by altering the direction of charge transfer with a second aromatic ring. Herein, the first theoretical framework of POM-based heteroaromatic rings is found to be another class of excellent NLO materials having double heteroaromatic rings. First hyperpolarizabilities of a large number of push-pull-substituted conjugated systems with heteroaromatic rings have been calculated. The β components were computed at the density functional theory (DFT) level (BP86 geometry optimizations and LB94 time-dependent DFT). The largest β values are obtained with a donor (hexamolybdates) on the benzene ring and an acceptor (-NO(2)) on pyrrole, thiophene, and furan rings. The pyrrole imido-substituted hexamolybdate (system 1c) has a considerably large first hyperpolarizability, 339.00 × 10(-30) esu, and it is larger than that of (arylimido)hexamolybdate, calculated as 0.302 × 10(-30) esu (reference system 1), because of the double aromatic rings in the heteroaromatic imido-substituted hexamolybdates. The heteroaromatic rings act as a conjugation bridge between the electron acceptor (-NO(2)) and donor (polyanion). The introduction of an electron donor into heteroaromatic rings significantly enhances the first hyperpolarizabilities because the electron-donating ability is substantially enhanced when the electron donor is attached to the heterocyclic aromatic rings. Interposing five-membered auxiliary fragments between strong donor (polyanion) or acceptor (-NO(2)) groups results in a large computed second-order NLO response. The present investigation provides important insight into the NLO properties of (heteroaromatic) imido-substituted hexamolybdate derivatives because these compounds exhibit enhanced hyperpolarizabilities compared to typical NLO arylimido hexamolybdates and heterocyclic aromatic rings reported in the literature.

A high-throughput in vitro ring assay for vasoactivity using magnetic 3D bioprinting

PubMed Central

Tseng, Hubert; Gage, Jacob A.; Haisler, William L.; Neeley, Shane K.; Shen, Tsaiwei; Hebel, Chris; Barthlow, Herbert G.; Wagoner, Matthew; Souza, Glauco R.

2016-01-01

Vasoactive liabilities are typically assayed using wire myography, which is limited by its high cost and low throughput. To meet the demand for higher throughput in vitro alternatives, this study introduces a magnetic 3D bioprinting-based vasoactivity assay. The principle behind this assay is the magnetic printing of vascular smooth muscle cells into 3D rings that functionally represent blood vessel segments, whose contraction can be altered by vasodilators and vasoconstrictors. A cost-effective imaging modality employing a mobile device is used to capture contraction with high throughput. The goal of this study was to validate ring contraction as a measure of vasoactivity, using a small panel of known vasoactive drugs. In vitro responses of the rings matched outcomes predicted by in vivo pharmacology, and were supported by immunohistochemistry. Altogether, this ring assay robustly models vasoactivity, which could meet the need for higher throughput in vitro alternatives. PMID:27477945

Complex Fluids at Interfaces and Interfaces of Complex Fluids

NASA Astrophysics Data System (ADS)

Nouri, Mariam

The present thesis deals with two independent projects and is consequently divided into two parts. The first part details a computational study of the fluid structure of ring-shaped molecules and their positional and orientational molecular organizations in different degrees of confinement, while the second part concerns an experimental study of phase behavior and interfacial phenomena in confined colloid-polymer systems. In the first part, ring-shaped molecules are studied using Monte Carlo simulation techniques in one, two and three dimensions. The model used to describe ring-shaped molecules is composed of hard-spheres linked together to form planar rigid rings. For rings of various sizes and for a wide range of densities, positional and orientational orderings are reported in forms of pair distribution functions of the ring centers and correlation functions of the ring normal orientations. Special emphasis is given to understand structural formation at interfaces, i.e., the structure and orderings of these molecules when they are confined to two dimensions. In a plane but the rings themselves are free to rotate around all axes, nematic ordering is observed at sufficiently high densities. In the second part, phase equilibria of confined aqueous colloid-polymer systems are studied experimentally using fluorescence microscopy. Aqueous mixtures of fluorescent polystyrene spheres and polyacrylamide are confined between a glass slide and a coverslip. The phase diagram is determined as a function of the colloidal and polymer concentrations. Liquid-liquid phase coexistence between a colloid-rich phase and a polymer-rich phase occurs at intermediate polymer concentrations, while liquid-solid phase coexistence between a polymer-rich liquid and a colloid-rich solid is observed at high polymer concentrations. Interfacial thickness and tension of the interface between these coexisting phases are measured using image analysis techniques. It is also observed that the colloid-rich solid and liquid domains coarsen mainly by Ostwald ripening.

Perception of Leitmotives in Richard Wagner's Der Ring des Nibelungen.

PubMed

Baker, David J; Müllensiefen, Daniel

2017-01-01

The music of Richard Wagner tends to generate very diverse judgments indicative of the complex relationship between listeners and the sophisticated musical structures in Wagner's music. This paper presents findings from two listening experiments using the music from Wagner's Der Ring des Nibelungen that explores musical as well as individual listener parameters to better understand how listeners are able to hear leitmotives, a compositional device closely associated with Wagner's music. Results confirm findings from a previous experiment showing that specific expertise with Wagner's music can account for a greater portion of the variance in an individual's ability to recognize and remember musical material compared to measures of generic musical training. Results also explore how acoustical distance of the leitmotives affects memory recognition using a chroma similarity measure. In addition, we show how characteristics of the compositional structure of the leitmotives contributes to their salience and memorability. A final model is then presented that accounts for the aforementioned individual differences factors, as well as parameters of musical surface and structure. Our results suggest that that future work in music perception may consider both individual differences variables beyond musical training, as well as symbolic features and audio commonly used in music information retrieval in order to build robust models of musical perception and cognition.

Perception of Leitmotives in Richard Wagner's Der Ring des Nibelungen

PubMed Central

Baker, David J.; Müllensiefen, Daniel

2017-01-01

The music of Richard Wagner tends to generate very diverse judgments indicative of the complex relationship between listeners and the sophisticated musical structures in Wagner's music. This paper presents findings from two listening experiments using the music from Wagner's Der Ring des Nibelungen that explores musical as well as individual listener parameters to better understand how listeners are able to hear leitmotives, a compositional device closely associated with Wagner's music. Results confirm findings from a previous experiment showing that specific expertise with Wagner's music can account for a greater portion of the variance in an individual's ability to recognize and remember musical material compared to measures of generic musical training. Results also explore how acoustical distance of the leitmotives affects memory recognition using a chroma similarity measure. In addition, we show how characteristics of the compositional structure of the leitmotives contributes to their salience and memorability. A final model is then presented that accounts for the aforementioned individual differences factors, as well as parameters of musical surface and structure. Our results suggest that that future work in music perception may consider both individual differences variables beyond musical training, as well as symbolic features and audio commonly used in music information retrieval in order to build robust models of musical perception and cognition. PMID:28522981

Remote synchronization of amplitudes across an experimental ring of non-linear oscillators

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

Minati, Ludovico, E-mail: lminati@ieee.org, E-mail: ludovico.minati@unitn.it, E-mail: lminati@istituto-besta.it

In this paper, the emergence of remote synchronization in a ring of 32 unidirectionally coupled non-linear oscillators is reported. Each oscillator consists of 3 negative voltage gain stages connected in a loop to which two integrators are superimposed and receives input from its preceding neighbour via a “mixing” stage whose gains form the main system control parameters. Collective behaviour of the network is investigated numerically and experimentally, based on a custom-designed circuit board featuring 32 field-programmable analog arrays. A diverse set of synchronization patterns is observed depending on the control parameters. While phase synchronization ensues globally, albeit imperfectly, for certainmore » control parameter values, amplitudes delineate subsets of non-adjacent but preferentially synchronized nodes; this cannot be trivially explained by synchronization paths along sequences of structurally connected nodes and is therefore interpreted as representing a form of remote synchronization. Complex topology of functional synchronization thus emerges from underlying elementary structural connectivity. In addition to the Kuramoto order parameter and cross-correlation coefficient, other synchronization measures are considered, and preliminary findings suggest that generalized synchronization may identify functional relationships across nodes otherwise not visible. Further work elucidating the mechanism underlying this observation of remote synchronization is necessary, to support which experimental data and board design materials have been made freely downloadable.« less

Remote synchronization of amplitudes across an experimental ring of non-linear oscillators.

PubMed

Minati, Ludovico

2015-12-01

In this paper, the emergence of remote synchronization in a ring of 32 unidirectionally coupled non-linear oscillators is reported. Each oscillator consists of 3 negative voltage gain stages connected in a loop to which two integrators are superimposed and receives input from its preceding neighbour via a "mixing" stage whose gains form the main system control parameters. Collective behaviour of the network is investigated numerically and experimentally, based on a custom-designed circuit board featuring 32 field-programmable analog arrays. A diverse set of synchronization patterns is observed depending on the control parameters. While phase synchronization ensues globally, albeit imperfectly, for certain control parameter values, amplitudes delineate subsets of non-adjacent but preferentially synchronized nodes; this cannot be trivially explained by synchronization paths along sequences of structurally connected nodes and is therefore interpreted as representing a form of remote synchronization. Complex topology of functional synchronization thus emerges from underlying elementary structural connectivity. In addition to the Kuramoto order parameter and cross-correlation coefficient, other synchronization measures are considered, and preliminary findings suggest that generalized synchronization may identify functional relationships across nodes otherwise not visible. Further work elucidating the mechanism underlying this observation of remote synchronization is necessary, to support which experimental data and board design materials have been made freely downloadable.

Future Synchrotron Light Sources Based on Ultimate Storage Rings

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

Cai, Yunhai; /SLAC

2012-04-09

The main purpose of this talk is to describe how far one might push the state of the art in storage ring design. The talk will start with an overview of the latest developments and advances in the design of synchrotron light sources based on the concept of an 'ultimate' storage ring. The review will establish how bright a ring based light source might be, where the frontier of technological challenges are, and what the limits of accelerator physics are. Emphasis will be given to possible improvements in accelerator design and developments in technology toward the goal of achieving anmore » ultimate storage ring. An ultimate storage ring (USR), defined as an electron ring-based light source having an emittance in both transverse planes at the diffraction limit for the range of X-ray wavelengths of interest for a scientific community, would provide very high brightness photons having high transverse coherence that would extend the capabilities of X-ray imaging and probe techniques beyond today's performance. It would be a cost-effective, high-coherence 4th generation light source, competitive with one based on energy recovery linac (ERL) technology, serving a large number of users studying material, chemical, and biological sciences. Furthermore, because of the experience accumulated over many decades of ring operation, it would have the great advantage of stability and reliability. In this paper we consider the design of an USR having 10-pm-rad emittance. It is a tremendous challenge to design a storage ring having such an extremely low emittance, a factor of 100 smaller than those in existing light sources, especially such that it has adequate dynamic aperture and beam lifetime. In many ultra-low emittance designs, the injection acceptances are not large enough for accumulation of the electron beam, necessitating on-axis injection where stored electron bunches are completely replaced with newly injected ones. Recently, starting with the MAX-IV 7-bend achromatic cell, we have made significant progress with the design of PEP-X, a USR that would inhabit the decommissioned PEP-II tunnel at SLAC. The enlargement of the dynamic aperture is largely a result of the cancellations of the 4th-order resonances in the 3rd-order achromats and the effective use of lattice optimization programs. In this paper, we will show those cancellations of the 4th-order resonances using an analytical approach based on the exponential Lie operators and the Poisson brackets. Wherever possible, our analytical results will be compared with their numerical counterparts. Using the derived formulae, we will construct 4th-order geometric achromats and use them as modules for the lattice of the PEP-X USR, noting that only geometric terms are canceled to the 4th order.« less

Controllable excitation of higher-order rogue waves in nonautonomous systems with both varying linear and harmonic external potentials

NASA Astrophysics Data System (ADS)

Jia, Heping; Yang, Rongcao; Tian, Jinping; Zhang, Wenmei

2018-05-01

The nonautonomous nonlinear Schrödinger (NLS) equation with both varying linear and harmonic external potentials is investigated and the semirational rogue wave (RW) solution is presented by similarity transformation. Based on the solution, the interactions between Peregrine soliton and breathers, and the controllability of the semirational RWs in periodic distribution and exponential decreasing nonautonomous systems with both linear and harmonic potentials are studied. It is found that the harmonic potential only influences the constraint condition of the semirational solution, the linear potential is related to the trajectory of the semirational RWs, while dispersion and nonlinearity determine the excitation position of the higher-order RWs. The higher-order RWs can be partly, completely and biperiodically excited in periodic distribution system and the diverse excited patterns can be generated for different parameter relations in exponential decreasing system. The results reveal that the excitation of the higher-order RWs can be controlled in the nonautonomous system by choosing dispersion, nonlinearity and external potentials.

“Click, Click, Cyclize”: A DOS Approach to Sultams Utilizing Vinyl Sulfonamide Linchpins

PubMed Central

Zhou, Aihua; Rayabarapu, Dinesh; Hanson, Paul R.

2009-01-01

A diversity-oriented synthesis (DOS) strategy termed “Click, Click, Cyclize” is reported. This approach relies on functional group (FG) pairing between a vinyl sulfonamide and an array of functional groups to synthesize skeletally diverse sultams. Several FG pairing pathways on central tertiary vinyl sulfonamide linchpins have been developed including intramolecular Heck, aza-Michael, ring-closing enyne metathesis, Pauson—Khand, and chemoselective oxidation/Baylis—Hillman reactions. PMID:19115841

Genetic diversity of resin yielder Pinus merkusii from West Java - Indonesia revealed by microsatellites marker

NASA Astrophysics Data System (ADS)

Susilowati, A.; Rachmat, H. H.; Siregar, I. Z.; Supriyanto

2018-02-01

Phenotypic observation of resin yielder Pinus merkusii showed higher value of genetic variation and narrow sense heritability values for resin production trait. This result indicated that genetic factor played as dominant aspect. However, further observation using molecular marker would still be needed to overcome the weakness of phenotypic observation. This study was carried out in order to characterize the genetic diversity and genetic differentiation of resin yielder genotype candidate P.merkusii using microsatellite markers and to characterize the genetic structure in the resin yielder populations. Seventy needle and inner bark samples were collected from resin yielder in Cijambu Seedling Seed Orchard (SSO) Sumedang, West Java and further divided into two genotype candidates (lower and high resin yielder). Seven microsatellites loci (pm01, pm04, pm05, pm07, pm08, pm09a, pm12, pde5 and SPAC 11.6) were used for detection of genetic diversity. Results showed that genetic diversity in higher resin candidates was (0.551), slightly different compared lower candidates (0.545). However, cluster analysis determined that higher resin yielder grouped with lower one. Molecular variation was found to be low among populations (21%) and high among individuals within the populations (79%). Private alleles were detected both in higher yielder and also normal population.

Investigation of various N-heterocyclic substituted piperazine versions of 5/ 7-{[2-(4-Aryl-piperazin-1-yl)-ethyl]-propyl-amino}-5,6,7,8-tetrahydro-naphthalen-2-ol: Effect on affinity and selectivity for dopamine D3 receptor

PubMed Central

Brown, Dennis A.; Mishra, Manoj; Zhang, Suhong; Biswas, Swati; Parrington, Ingrid; Antonio, Tamara; Reith, Maarten E. A.; Dutta, Aloke K.

2009-01-01

Here we report on the design and synthesis of several heterocyclic analogues belonging to the 5/ 7-{[2-(4-aryl-piperazin-1-yl)-ethyl]-propyl-amino}-5,6,7,8-tetrahydro-naphthalen-2-ol series of molecules. Compounds were subjected to [3H]spiperone binding assays, carried out with HEK-293 cells expressing either D2 or D3 dopamine receptors, in order to evaluate their inhibition constant (Ki) at these receptors. Results indicate that N-substitution on the piperazine ring can accommodate various substituted indole rings. The results also show that in order to maintain high affinity and selectivity for the D3 receptor the heterocyclic ring does not need to be connected directly to the piperazine ring as the majority of compounds included here are linked either via an amide or a methylene linker to the heterocyclic moiety. The enantiomers of the most potent racemic compound 10e exhibited differential activity with (-)-10e (Ki; D2 = 47.5 nM, D3 = 0.57 nM) displaying higher affinity at both D2 and D3 receptors compared to its enantiomer (+)-10e (Ki; D2 = 113 nM, D3 = 3.73 nM). Additionally, compound (-)-10e was more potent and selective for the D3 receptor compared to either 7-OH-DPAT or 5-OH-DPAT. Among the bioisosteric derivatives, the indazole derivative 10g and benzo[b]thiophene derivative 10i exhibited the highest affinity for D2 and D3 receptors. In the functional GTPγS binding study, one of the lead molecules, (-)-15, exhibited potent agonist activity at both D2 and D3 receptors with preferential activity at D3. PMID:19427222

Self-Consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 1; Waves in Multi Ion Magnetosphere

NASA Technical Reports Server (NTRS)

Khazanov, G. V.; Gumayunov, K. V.; Gallagher, D. L.; Kozyra, J. U.

2006-01-01

The further development of a self-consistent theoretical model of interacting ring current ions and electromagnetic ion cyclotron waves [Khazanov et al., 2003] is presented. In order to adequately take into account the wave propagation and refraction in a multi-ion plasmasphere, we explicitly include the ray tracing equations in our previous self-consistent model and use the general form of the wave kinetic equation. This is a major new feature of the present model and, to the best of our knowledge, the ray tracing equations for the first time are explicitly employed on a global magnetospheric scale in order to self-consistently simulate spatial, temporal, and spectral evolutions of the ring current and electromagnetic ion cyclotron waves. To demonstrate the effects of EMIC wave propagation and refraction on the EMIC wave energy distributions and evolution we simulate the May 1998 storm. The main findings of our simulation can be summarized as follows. First, due to the density gradient at the plasmapause, the net wave refraction is suppressed, and He(+)-mode grows preferably at plasmapause. This result is in a total agreement with the previous ray tracing studies, and very clear observed in presented B-field spectrograms. Second, comparison the global wave distributions with the results from other ring current model [Kozyra et al., 1997] reveals that our model provides more intense and higher plasmapause organized distributions during the May, 1998 storm period. Finally, the found He(+)-mode energy distributions are not Gaussian distributions, and most important that wave energy can occupy not only the region of generation, i. e. the region of small wave normal angles, but the entire wave normal angle region and even only the region near 90 degrees. The latter is extremely crucial for energy transfer to thermal plasmaspheric electrons by resonant Landau damping, and subsequent downward heat transport and excitation of stable auroral red arcs.

Resonant circuit which provides dual frequency excitation for rapid cycling of an electromagnet

DOEpatents

Praeg, Walter F.

1984-01-01

Disclosed is a ring magnet control circuit that permits synchrotron repetition rates much higher than the frequency of the cosinusoidal guide field of the ring magnet during particle acceleration. the control circuit generates cosinusoidal excitation currents of different frequencies in the half waves. During radio frequency acceleration of the particles in the synchrotron, the control circuit operates with a lower frequency cosine wave and thereafter the electromagnets are reset with a higher frequency half cosine wave. Flat-bottom and flat-top wave shaping circuits maintain the magnetic guide field in a relatively time-invariant mode during times when the particles are being injected into the ring magnets and when the particles are being ejected from the ring magnets.

Self-focusing of ultraintense femtosecond optical vortices in air.

PubMed

Polynkin, P; Ament, C; Moloney, J V

2013-07-12

Our experiments show that the critical power for self-focusing collapse of femtosecond vortex beams in air is significantly higher than that of a flattop beam and grows approximately linearly with the vortex order. With less than 10% of initial transverse intensity modulation of the beam profiles, the dominant mode of self-focusing collapse is the azimuthal breakup of the vortex rings into individual filaments, the number of which grows with the input beam power. The generated bottlelike distributions of plasma filaments rotate on propagation in the direction determined by the sense of vorticity.

Proceedings of the 1993 Particle Accelerator Conference Held in Washington, DC on May 17-20, 1993. Volume 3

DTIC Science & Technology

1993-05-20

mm-mrad 10 mm-md I. INTRODUCTION Higher -order modes (HOMs) of the SR single cell cavityThe 20-MeV linac beam at the Argonne Chemistry are studied by...energy proton storage rings: RHIC and the SSC. I. INTRODUCTION We have proposed to build spin rotators with two k transverse wigglers of many poles...integral of gauge field; beam Is always polarized, the magnetic potential flux line of (4) edot quantization of path integral in sate sae bunch spin are

Application of Remote-Sensing Observations for Detecting Patterns of Localization of PGM Mineralization of Western Bushveld

NASA Astrophysics Data System (ADS)

Milovsky, G. A.; Ishmukhametova, V. T.; Orlyankin, V. N.; Shemyakina, E. M.

2017-12-01

The differentiated Bushveld complex is studied by remote-space and gravimagnetic methods. The syncline of Western Bushveld is recognized in the southwestern part of the complex, which is characterized by a radial and ring structure of the higher order. The structures, which control the localization of Pt mineralization, are revealed and the possible use of the Landsat 7 ETM+ multizonal space survey is shown for recognizing the rocks of the Basal, Critical, Main, and Upper zones of the norite complex of Western Bushveld.

Reflective optical imaging systems with balanced distortion

DOEpatents

Hudyma, Russell M.

2001-01-01

Optical systems compatible with extreme ultraviolet radiation comprising four reflective elements for projecting a mask image onto a substrate are described. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical systems are particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput, and allows higher semiconductor device density. The inventive optical systems are characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.

Excitation of high-radial-order Laguerre-Gaussian modes in a solid-state laser using a lower-loss digitally controlled amplitude mask

NASA Astrophysics Data System (ADS)

Bell, T.; Hasnaoui, A.; Ait-Ameur, K.; Ngcobo, S.

2017-10-01

In this paper we experimentally demonstrate selective excitation of high-radial-order Laguerre-Gaussian (LG p or LG{}p,0) modes with radial order p = 1-4 and azimuthal order l = 0 using a diode-pump solid-state laser (DPSSL) that is digitally controlled by a spatial light modulator (SLM). We encoded an amplitude mask containing p-absorbing rings, of various incompleteness (segmented) on grey-scale computer-generated digital holograms, and displayed them on an SLM which acted as an end mirror of the diode-pumped solid-state digital laser. The various incomplete (α) p-absorbing rings were digitally encoded to match the zero-intensity nulls of the desired LG p mode. We show that the creation of LG p , for p = 1 to p = 4, only requires an incomplete circular p-absorbing ring that has a completeness of ≈37.5%, giving the DPSSL resonator a lower pump threshold power while maintaining the same laser characteristics (such as beam propagation properties).

Electrostatic forces in planetary rings

NASA Technical Reports Server (NTRS)

Goertz, C. K.; Shan, Linhua; Havnes, O.

1988-01-01

The average charge on a particle in a particle-plasma cloud, the plasma potential inside the cloud, and the Coulomb force acting on the particle are calculated. The net repulsive electrostatic force on a particle depends on the plasma density, temperature, density of particles, particle size, and the gradient of the particle density. In a uniformly dense ring the electrostatic repulsion is zero. It is also shown that the electrostatic force acts like a pressure force, that even a collisionless ring can be stable against gravitational collapse, and that a finite ring thickness does not necessarily imply a finite velocity dispersion. A simple criterion for the importance of electrostatic forces in planetary rings is derived which involves the calculation of the vertical ring thickness which would result if only electrostatic repulsion were responsible for the finite ring thickness. Electrostatic forces are entirely negligible in the main rings of Saturn and the E and G rings. They may also be negligible in the F ring. However, the Uranian rings and Jupiter's ring seem to be very much influenced by electrostatic repulsion. In fact, electrostatic forces could support a Jovian ring which is an order of magnitude more dense than observed.

The structure of Jupiter’s main ring from New Horizons: A comparison with other ring-moon systems

NASA Astrophysics Data System (ADS)

Chancia, Robert; Hedman, Matthew

2018-04-01

During New Horizon’s Jupiter flyby in 2007, the Long-Range Reconnaissance Imager (LORRI) took several images of the planet’s main ring. The data set contains two extended image-movies of the main ring, along with several brief observations at varying ring azimuths, and a small set of high phase angle images. Thus far, the only published work on the New Horizons Jupiter rings data set found seven bright clumps with sub-km equivalent radii embedded in the main ring (Showalter et al. 2007 Science). In this work, we searched the inner region of the main ring for any structures that might be perturbed at the 3:2 resonances with the rotation of Jupiter’s magnetic field or massive storms. We also examined the structure of the outer main ring in order to assess how it is shaped by the small moons Metis and Adrastea. Some of the features seen in Jupiter’s main ring are similar to those found in other dusty rings around Saturn, Uranus, and Neptune. By comparing these different rings, we can gain a better understanding of how small moons sculpt tenuous rings.

Mechanisms of adaptive evolution. Darwinism and Lamarckism restated.

PubMed

Aboitiz, F

1992-07-01

This article discusses the conceptual basis of the different mechanisms of adaptive evolution. It is argued that only two such mechanisms may conceivably exist, Lamarckism and Darwinism. Darwinism is the fundamental process generating the diversity of species. Some aspects of the gene-centered approach to Darwinism are questioned, since they do not account for the generation of biological diversity. Diversity in biological design must be explained in relation to the diversity of interactions of organisms (or other higher-level units) with their environment. This aspect is usually overlooked in gene-centered views of evolution. A variant of the gene-selectionist approach has been proposed to account for the spread of cultural traits in human societies. Alternatively, I argue that social evolution is rather driven by what I call pseudo-Lamarckian inheritance. Finally, I argue that Lamarckian and pseudo-Lamarckian inheritance are just special cases of faithful replication which are found in the development of some higher-order units, such as multicellular organisms and human societies.

Frequency equation for the submicron CMOS ring oscillator using the first order characterization

NASA Astrophysics Data System (ADS)

Koithyar, Aravinda; Ramesh, T. K.

2018-05-01

By utilizing the first order behavior of the device, an equation for the frequency of operation of the submicron CMOS ring oscillator is presented. A 5-stage ring oscillator is utilized as the initial design, with different Beta ratios, for the computation of the operating frequency. Later on, the circuit simulation is performed from 5-stage till 23-stage, with the range of oscillating frequency being 3.0817 and 0.6705 GHz respectively. It is noted that the output frequency is inversely proportional to the square of the device length, and when the value of Beta ratio is used as 2.3, a difference of 3.64% is observed on an average, in between the computed and the simulated values of frequency. As an outcome, the derived equation can be utilized, with the inclusion of an empirical constant in general, for arriving at the ring oscillator circuit’s output frequency.

Aperture Effects in the Long Slit Spectrophotometry of the Polar Ring Galaxy IIZw71

NASA Astrophysics Data System (ADS)

Pérez-Montero, E.; García-Benito, R.; Díaz, Á. I.; Pérez, E.; Kehrig, C.

2008-10-01

Polar ring galaxies are composed by an early type galaxy and a polar ring rotating around it and which is rich in gas, dust and star formation. IIZw71 is catalogued as a blue compact dwarf galaxy and as a probable polar ring galaxy (Whitmore et al. 1990). The formation of the polar ring and the very luminous bursts of star formation along it, is a consequence of the interaction with a close companion, IIZw70, situated at 18.1 kpc (Cox et al. 2001). We have carried out spectrophotometric observations of the bursts of star formation along the polar ring in order to study differences in the physical properties or the star formation histories between the knots

Structural analysis of the space shuttle solid rocket booster/external tank attach ring

NASA Technical Reports Server (NTRS)

Dorsey, John T.

1988-01-01

An External Tank (ET) attach ring is used in the Space Shuttle System to transfer lateral loads between the ET and the Solid Rocket Booster (SRB). Following the Challenger (51-L) accident, the flight performance of the ET attach ring was reviewed, and negative margins of safety and failed bolts in the attach ring were subsequently identified. The analyses described in this report were performed in order to understand the existing ET attach ring structural response to motor case internal pressurization as well as to aid in an ET attach ring redesign effort undertaken by NASA LaRC. The finite element model as well as the results from linear and nonlinear static structural analyses are described.

A Transmissible Plasmid Controlling Camphor Oxidation in Pseudomonas putida

PubMed Central

Rheinwald, J. G.; Chakrabarty, A. M.; Gunsalus, I. C.

1973-01-01

Earlier papers demonstrated an extensive genetic exchange among fluorescent Pseudomonads; this one documents for genes specifying enzymes of peripheral dissimilation an extrachromosomal array, segregation, and frequent interstrain transfer. An hypothesis is presented of a general mechanism for the formation and maintenance of metabolic diversity. The example used, the path of oxidative cleavage of the carbocyclic rings of the bicyclic monoterpene D- and L-camphor, terminates in acetate release and isobutyrate chain debranching. By transduction, two gene linkage groups are shown for the reactions before and after isobutyrate. The group for reactions before isobutyrate is plasmid borne, contransferable by conjugation, mitomycin curable, and shows a higher segregation rate from cells that are multiplasmid rather than carrying a single plasmid. The genes that code for isobutyrate and essential anaplerotic and amphibolic metabolism are chromosomal. By conjugation plasmid-borne genes are transferred at a higher frequency than are chromosomal, and are transferred in homologous crosses more frequently than between heterologous species. Most isobutyrate-positive fluorescent pseudomonad strains will accept and express the camphor plasmid. PMID:4351810

Apennine Front revisited - Diversity of Apollo 15 highland rock types

NASA Technical Reports Server (NTRS)

Lindstrom, Marilyn M.; Marvin, Ursula B.; Vetter, Scott K.; Shervais, John W.

1988-01-01

The Apollo 15 landing site is geologically the most complex of the Apollo sites, situated at a mare-highland interface within the rings of two of the last major basin-forming impacts. Few of the Apollo 15 samples are ancient highland rocks derived from the early differentiation of the moon, or impact melts from major basin impacts. Most of the samples are regolith breccias containing abundant clasts of younger volcanic mare and KREEP basalts. The early geologic evolution of the region can be understood only by examining the small fragments of highland rocks found in regolith breccias and soils. Geochemical and petrologic studies of clasts and matrices of three impact melt breccias and four regolith breccias are presented. Twelve igneous and metamorphic rocks show extreme diversity and include a new type of ferroan norite. Twenty-five samples of highland impact melt are divided into groups based on composition. These impact melts form nearly a continuum over more than an order of magnitude in REE concentrations. This continuum may result from both major basin impacts and younger local events. Highland rocks from the Apennine Front include most of the highland rock types found at all of the other sites. An extreme diversity of highland rocks is a fundamental characteristic of the Apennine Front and is a natural result of its complex geologic evolution.

Structural effects of Cu(II)-coordination in the octapeptide region of the human prion protein.

PubMed

Riihimäki, Eva-Stina; Martínez, José Manuel; Kloo, Lars

2008-05-14

The copper-binding ability of the prion protein is thought to be central to its function. The structural effects of copper coordination in the octapeptide region of the human prion protein have been investigated by molecular dynamics simulations. Simulations were performed with the apo state, in order to investigate the behavior of the region without copper ions, as well as with the octapeptide region in the presence of copper ions. While the structure of the apo state is greatly influenced by the interaction between the rings in the histidine, tryptophan and proline residues, the region shows evidence of highly ordered coordination sites in the presence of copper ions. The position of the tryptophan indole ring is stabilized by cation-pi interactions. Two stable orientations of the indole ring with respect to the equatorial coordination plane of copper were observed, which showed that the indole ring can reside on both sides of the coordination plane. The interaction with the indole ring was found to occur without a mediating axial water molecule.

Transparent arrays of silver nanowire rings driven by evaporation of sessile droplets

NASA Astrophysics Data System (ADS)

Wang, Xiaofeng; Kang, Giho; Seong, Baekhoon; Chae, Illkyeong; Teguh Yudistira, Hadi; Lee, Hyungdong; Kim, Hyunggun; Byun, Doyoung

2017-11-01

A coffee-ring pattern can be yielded on the three-phase contact line following evaporation of sessile droplets with suspended insoluble solutes, such as particles, DNA molecules, and mammalian cells. The formation of such coffee-ring, together with their suppression has been applied in printing and coating technologies. We present here an experimental study on the assembly of silver nanowires inside an evaporating droplet of a colloidal suspension. The effects of nanowire length and concentration on coffee-ring formation of the colloidal suspension were investigated. Several sizes of NWs with an aspect ratio between 50 and 1000 were systematically investigated to fabricate coffee-ring patterns. Larger droplets containing shorter nanowires formed clearer ring deposits after evaporation. An order-to-disorder transition of the nanowires’ alignment was found inside the rings. A printing technique with the evaporation process enabled fabrication of arrays of silver nanowire rings. We could manipulate the patterns silver nanowire rings, which might be applied to the transparent and flexible electrode.

Genetically tunable M13 phage films utilizing evaporating droplets.

PubMed

Alberts, Erik; Warner, Chris; Barnes, Eftihia; Pilkiewicz, Kevin; Perkins, Edward; Poda, Aimee

2018-01-01

This effort utilizes a genetically tunable system of bacteriophage to evaluate the effect of charge, temperature and particle concentration on biomaterial synthesis utilizing the coffee ring (CR) effect. There was a 1.6-3 fold suppression of the CR at higher temperatures while maintaining self-assembled structures of thin films. This suppression was observed in phage with charged and uncharged surface chemistry, which formed ordered and disordered assemblies respectively, indicating CR suppression is not dependent on short-range ordering or surface chemistry. Analysis of the drying process suggests weakened capillary flow at elevated temperatures caused CR suppression and could be further enhanced for controlled assembly for advanced biomaterials. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

On the plasmonic properties of a symmetry-breaking silver nanoring structure

NASA Astrophysics Data System (ADS)

Jiang, Bozhi; Sun, Cheng

2018-07-01

This work reports on a study regarding the plasmonic properties of a symmetry-breaking silver nanoring structure, in the wavelength range of 0.6-4.5 μm. A broken silver ring with a certain angle, as well as a full ring composed of silver and other metallic/dielectric materials, are proposed. The extinction efficiencies of the nanostructure are numerically calculated with several parameters being varied, including the broken angle, the inner and outer radii, and the thickness of the broken ring, as well as the material in the composite full ring. Multiple plasmonic resonances are observed in the extinction efficiency curves, which are attributed to the quadrupolar, octupolar, and hexadecapolar resonance modes that are revealed by the electric field distributions. The results demonstrate that the high-order modes can be altered, by varying the value of the broken angle of the ring. It is also illustrated that the resonance wavelength and the full width at half maximum of certain high-order plasmonic resonance peaks can be tuned in the wavelength range studied, by adjusting the values of the geometrical parameters of the nanoring. The plasmonic characteristics of the symmetry-breaking nanoring structure revealed in this study, provide a great platform for the designs of plasmonic devices utilizing the high-order plasmonic resonances. Besides, it is also proposed a scheme to switch the device between the multi-wavelength and single-wavelength modes.

Rhodium-catalyzed Intra- and Intermolecular [5+2] Cycloaddition of 3-Acyloxy-1,4-enyne and Alkyne with Concomitant 1,2-Acyloxy Migration

PubMed Central

Shu, Xing-Zhong; Li, Xiaoxun; Shu, Dongxu; Huang, Suyu; Schienebeck, Casi M.; Zhou, Xin; Robichaux, Patrick J.; Tang, Weiping

2012-01-01

A new type of rhodium-catalyzed [5+2] cycloaddition was developed for the synthesis of seven-membered rings with diverse functionalities. The ring formation was accompanied by a 1,2-acyloxy migration event. The 5- and 2-carbon components of the cycloaddition are 3-acyloxy-1,4-enynes (ACEs) and alkynes respectively. Cationic rhodium (I) catalysts worked most efficiently for the intramolecular cycloaddition, while only neutral rhodium (I) complexes could facilitate the intermolecular reaction. In both cases, electron-poor phosphite or phosphine ligands often improved the efficiency of the cycloadditions. The scope of ACEs and alkynes was investigated in both intra- and intermolecular reactions. The resulting seven-membered ring products have three double bonds that could be selectively functionalized. PMID:22364320

Sediment record of polycyclic aromatic hydrocarbons in the Liaohe River Delta wetland, Northeast China: Implications for regional population migration and economic development.

PubMed

Ma, Chuanliang; Lin, Tian; Ye, Siyuan; Ding, Xigui; Li, Yuanyuan; Guo, Zhigang

2017-03-01

The polycyclic aromatic hydrocarbons (PAHs) of a 210 Pb-dated sediment core extracted from the Liaohe River Delta wetland were measured to reconstruct the sediment record of PAHs and its response to human activity for the past 300 years in Northeast China. The concentrations of the 16 U.S. Environmental Protection Agency priority PAHs (∑16PAHs) ranged from 46 to 1167 ng g -1 in this sediment core. The concentrations of the 16 PAHs (especially 4- and 5+6-ring PAHs) after the 1980s (surface sediments 0-6 cm) were one or two orders of magnitudes higher than those of the down-core samples. The exponential growth of 4-ring and 5+6-ring PAH concentrations after the 1980s responded well to the increased energy consumption and number of civil vehicles resulting from the rapid economic development in China. Prior to 1950, relatively low levels of the 16 PAHs and a high proportion of 2+3-ring PAHs was indicative of biomass burning as the main source of the PAHs. A significant increase in the 2 + 3 ring PAH concentration from the 1860s-1920s was observed and could be attributed to a constant influx of population migration into Northeast China. It was suggested that the link between historical trend of PAHs and population or energy use involves two different economic stages. Typically, in an agricultural economy, the greater the population size, the greater the emission of PAHs from biomass burning, while in an industrial economy, the increase in sedimentary PAH concentrations is closely related to increasing energy consumption of fossil fuels. Copyright © 2016 Elsevier Ltd. All rights reserved.

Decay of helical and nonhelical magnetic knots

NASA Astrophysics Data System (ADS)

Candelaresi, Simon; Brandenburg, Axel

2011-07-01

We present calculations of the relaxation of magnetic field structures that have the shape of particular knots and links. A set of helical magnetic flux configurations is considered, which we call n-foil knots of which the trefoil knot is the most primitive member. We also consider two nonhelical knots; namely, the Borromean rings as well as a single interlocked flux rope that also serves as the logo of the Inter-University Centre for Astronomy and Astrophysics in Pune, India. The field decay characteristics of both configurations is investigated and compared with previous calculations of helical and nonhelical triple-ring configurations. Unlike earlier nonhelical configurations, the present ones cannot trivially be reduced via flux annihilation to a single ring. For the n-foil knots the decay is described by power laws that range form t-2/3 to t-1/3, which can be as slow as the t-1/3 behavior for helical triple-ring structures that were seen in earlier work. The two nonhelical configurations decay like t-1, which is somewhat slower than the previously obtained t-3/2 behavior in the decay of interlocked rings with zero magnetic helicity. We attribute the difference to the creation of local structures that contain magnetic helicity which inhibits the field decay due to the existence of a lower bound imposed by the realizability condition. We show that net magnetic helicity can be produced resistively as a result of a slight imbalance between mutually canceling helical pieces as they are being driven apart. We speculate that higher order topological invariants beyond magnetic helicity may also be responsible for slowing down the decay of the two more complicated nonhelical structures mentioned above.

Removal and Repositioning of Intracorneal Ring Segments: Improving Corneal Topography and Clinical Outcomes in Keratoconus and Ectasia.

PubMed

Chan, Kahei; Hersh, Peter S

2017-02-01

To evaluate the efficacy of removal and relocation of intracorneal ring segments for improving outcomes in treatment of keratoconus and corneal ectasia. This is a retrospective case series conducted at a cornea and refractive surgery subspecialty practice setting. Patients with previous insertion of 2 intracorneal ring segments underwent surgical removal and repositioning of segments because of unsatisfactory visual and topographic outcomes. The principal outcomes included uncorrected and corrected visual acuities, manifest refraction, topography-derived maximum keratometry (Kmax), inferior-superior topography power difference (I - S), and higher-order aberration profile derived from wavefront analysis. Three patients are presented in this case series. Uncorrected visual acuity improved in all eyes by an average of 2.75 lines. Corrected visual acuity improved in 2 eyes and remained unchanged in 1 eye. Refractive astigmatism decreased in all patients by an average of 2.50 D. Kmax decreased by an average of 1.43 D. All patients had improvement in the I - S value with a mean decrease of 5.13 D. Topography-guided repositioning and/or replacement of corneal ring segments can result in improved topographic, optical, and visual outcomes in patients in whom the initial result is suboptimal. In these cases, a single segment repositioned beneath the cone resulted in an improved outcome. Analysis of corneal topography can guide the surgeon in treatment planning and can suggest patients in whom such an effort will be rewarded with better results.

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

Petković, Ivana; Lollo, A.; Glazman, L. I.

The properties of one-dimensional superconductors are strongly influenced by topological fluctuations of the order parameter, known as phase slips, which cause the decay of persistent current in superconducting rings and the appearance of resistance in superconducting wires. Despite extensive work, quantitative studies of phase slips have been limited by uncertainty regarding the order parameter’s free-energy landscape. Here we show detailed agreement between measurements of the persistent current in isolated flux-biased rings and Ginzburg–Landau theory over a wide range of temperature, magnetic field and ring size; this agreement provides a quantitative picture of the free-energy landscape. Furthermore, we also demonstrate thatmore » phase slips occur deterministically as the barrier separating two competing order parameter configurations vanishes. These results will enable studies of quantum and thermal phase slips in a well-characterized system and will provide access to outstanding questions regarding the nature of one-dimensional superconductivity.« less

Structural diversity and electronic properties in potassium silicides

NASA Astrophysics Data System (ADS)

Hao, Chun-Mei; Li, Yunguo; Huang, Hong-Mei; Li, Yan-Ling

2018-05-01

Stable potassium silicides in the complete compositional landscape were systematically explored up to 30 GPa using the variable-composition evolutionary structure prediction method. The results show that K4Si, K3Si, K5Si2, K2Si, K3Si2, KSi, KSi2, KSi3, and K8Si46 have their stability fields in the phase diagram. The spatial dimensional diversity of polymerized silicon atoms (0D "isolated" anion, dimer, Si4 group, 1D zigzag chain, 2D layer, and 3D network) under the potassium sublattice was uncovered as silicon content increases. Especially, the 2D layered silicon presents interestingly a variety of shapes, such as the "4 + 6" ring, "4 + 8"ring, and 8-membered ring. K-Si bonding exhibits a mixed covalency and ionicity, while Si-Si bonding is always of covalent character. Semiconductivity or metallicity mainly depends on the form of sublattices and K:Si ratio, which allows us to find more semiconductors in the Si-rich side when closed-shell K cations are encompassed by polymerized Si. The semiconducting silicides present strong absorption in the infrared and visible light range. These findings open up the avenue for experimental synthesis of alkali metal-IVA compounds and potential applications as battery electrode materials or photoelectric materials.

Three-Dimensional Multiscale, Multistable, and Geometrically Diverse Microstructures with Tunable Vibrational Dynamics Assembled by Compressive Buckling.

PubMed

Ning, Xin; Wang, Heling; Yu, Xinge; Soares, Julio A N T; Yan, Zheng; Nan, Kewang; Velarde, Gabriel; Xue, Yeguang; Sun, Rujie; Dong, Qiyi; Luan, Haiwen; Lee, Chan Mi; Chempakasseril, Aditya; Han, Mengdi; Wang, Yiqi; Li, Luming; Huang, Yonggang; Zhang, Yihui; Rogers, John

2017-04-11

Microelectromechanical systems remain an area of significant interest in fundamental and applied research due to their wide ranging applications. Most device designs, however, are largely two-dimensional and constrained to only a few simple geometries. Achieving tunable resonant frequencies or broad operational bandwidths requires complex components and/or fabrication processes. The work presented here reports unusual classes of three-dimensional (3D) micromechanical systems in the form of vibratory platforms assembled by controlled compressive buckling. Such 3D structures can be fabricated across a broad range of length scales and from various materials, including soft polymers, monocrystalline silicon, and their composites, resulting in a wide scope of achievable resonant frequencies and mechanical behaviors. Platforms designed with multistable mechanical responses and vibrationally de-coupled constituent elements offer improved bandwidth and frequency tunability. Furthermore, the resonant frequencies can be controlled through deformations of an underlying elastomeric substrate. Systematic experimental and computational studies include structures with diverse geometries, ranging from tables, cages, rings, ring-crosses, ring-disks, two-floor ribbons, flowers, umbrellas, triple-cantilever platforms, and asymmetric circular helices, to multilayer constructions. These ideas form the foundations for engineering designs that complement those supported by conventional, microelectromechanical systems, with capabilities that could be useful in systems for biosensing, energy harvesting and others.

A structural analysis of the AAA+ domains in Saccharomyces cerevisiae cytoplasmic dynein

PubMed Central

Gleave, Emma S.; Schmidt, Helgo; Carter, Andrew P.

2014-01-01

Dyneins are large protein complexes that act as microtubule based molecular motors. The dynein heavy chain contains a motor domain which is a member of the AAA+ protein family (ATPases Associated with diverse cellular Activities). Proteins of the AAA+ family show a diverse range of functionalities, but share a related core AAA+ domain, which often assembles into hexameric rings. Dynein is unusual because it has all six AAA+ domains linked together, in one long polypeptide. The dynein motor domain generates movement by coupling ATP driven conformational changes in the AAA+ ring to the swing of a motile element called the linker. Dynein binds to its microtubule track via a long antiparallel coiled-coil stalk that emanates from the AAA+ ring. Recently the first high resolution structures of the dynein motor domain were published. Here we provide a detailed structural analysis of the six AAA+ domains using our Saccharomycescerevisiae crystal structure. We describe how structural similarities in the dynein AAA+ domains suggest they share a common evolutionary origin. We analyse how the different AAA+ domains have diverged from each other. We discuss how this is related to the function of dynein as a motor protein and how the AAA+ domains of dynein compare to those of other AAA+ proteins. PMID:24680784

Inferring genetic interactions from comparative fitness data

PubMed Central

2017-01-01

Darwinian fitness is a central concept in evolutionary biology. In practice, however, it is hardly possible to measure fitness for all genotypes in a natural population. Here, we present quantitative tools to make inferences about epistatic gene interactions when the fitness landscape is only incompletely determined due to imprecise measurements or missing observations. We demonstrate that genetic interactions can often be inferred from fitness rank orders, where all genotypes are ordered according to fitness, and even from partial fitness orders. We provide a complete characterization of rank orders that imply higher order epistasis. Our theory applies to all common types of gene interactions and facilitates comprehensive investigations of diverse genetic interactions. We analyzed various genetic systems comprising HIV-1, the malaria-causing parasite Plasmodium vivax, the fungus Aspergillus niger, and the TEM-family of β-lactamase associated with antibiotic resistance. For all systems, our approach revealed higher order interactions among mutations. PMID:29260711

Inferring genetic interactions from comparative fitness data.

PubMed

Crona, Kristina; Gavryushkin, Alex; Greene, Devin; Beerenwinkel, Niko

2017-12-20

Darwinian fitness is a central concept in evolutionary biology. In practice, however, it is hardly possible to measure fitness for all genotypes in a natural population. Here, we present quantitative tools to make inferences about epistatic gene interactions when the fitness landscape is only incompletely determined due to imprecise measurements or missing observations. We demonstrate that genetic interactions can often be inferred from fitness rank orders, where all genotypes are ordered according to fitness, and even from partial fitness orders. We provide a complete characterization of rank orders that imply higher order epistasis. Our theory applies to all common types of gene interactions and facilitates comprehensive investigations of diverse genetic interactions. We analyzed various genetic systems comprising HIV-1, the malaria-causing parasite Plasmodium vivax , the fungus Aspergillus niger , and the TEM-family of β-lactamase associated with antibiotic resistance. For all systems, our approach revealed higher order interactions among mutations.

Markov models of genome segmentation

NASA Astrophysics Data System (ADS)

Thakur, Vivek; Azad, Rajeev K.; Ramaswamy, Ram

2007-01-01

We introduce Markov models for segmentation of symbolic sequences, extending a segmentation procedure based on the Jensen-Shannon divergence that has been introduced earlier. Higher-order Markov models are more sensitive to the details of local patterns and in application to genome analysis, this makes it possible to segment a sequence at positions that are biologically meaningful. We show the advantage of higher-order Markov-model-based segmentation procedures in detecting compositional inhomogeneity in chimeric DNA sequences constructed from genomes of diverse species, and in application to the E. coli K12 genome, boundaries of genomic islands, cryptic prophages, and horizontally acquired regions are accurately identified.

Diverse Reactions of Thiophenes, Selenophenes, and Tellurophenes with Strongly Oxidizing I(III) PhI(L)2 Reagents.

PubMed

Egalahewa, Sathsara; Albayer, Mohammad; Aprile, Antonino; Dutton, Jason L

2017-02-06

We report the outcomes of the reactions of aromatic group 16 thiophene, selenophene, and tellurophene rings with the I(III) oxidants PhI(OAc)(OTf) and [PhI(Pyr) 2 ][OTf] 2 (Pyr = pyridine). In all reactions, oxidative processes take place, with generation of PhI as the reduction product. However, with the exception of tellurophene with PhI(OAc)(OTf), +4 oxidation state complexes are not observed, but rather a variety of other processes occur. In general, where a C-H unit is available on the 5-membered ring, an electrophilic aromatic substitution reaction of either -IPh or pyridine onto the ring occurs. When all positions are blocked, reactions with PhI(OAc)(OTf) give acetic and triflic anhydride as the identifiable oxidative byproducts, while [PhI(Pyr) 2 ][OTf] 2 gives pyridine electrophilic aromatic substitution onto the peripheral rings. Qualitative mechanistic studies indicate that the presence of the oxidizable heteroatom is required for pyridine to act as an electrophile in a substantial manner.

Observing Planetary Rings and Small Satellites with the James Webb Space Telescope: Science Justification and Observation Requirements

NASA Technical Reports Server (NTRS)

Tiscareno, Matthew S.; Showalter, Mark R.; French, Richard G.; Burns, Joseph A.; Cuzzi, Jeffrey N.; de Pater, Imke; Hamilton, Douglas P.; Hedman, Matthew M.; Nicholson, Philip D.; Tamayo, Daniel;

An initial framework for the language of higher-order thinking mathematics practices

NASA Astrophysics Data System (ADS)

Staples, Megan E.; Truxaw, Mary P.

2012-09-01

This article presents an examination of the language demands of cognitively demanding tasks and proposes an initial framework for the language demands of higher-order mathematics thinking practices. We articulate four categories for this framework: language of generalisation, language of comparison, language of proportional reasoning, and language of analysing impact. These categories were developed out of our collaborative work to design and implement higher-order thinking tasks with a group of Grade 9 (14- and 15-year-olds) teachers teaching in a linguistically diverse setting; analyses of student work samples on these tasks; and our knowledge of the literature. We describe each type of language demand and then analyse student work in each category to reveal linguistic challenges facing students as they engage these mathematical tasks. Implications for teaching and professional development are discussed.

FIBER AND INTEGRATED OPTICS: Integrated optical passive ring resonator for optical gyroscopes

NASA Astrophysics Data System (ADS)

Baĭborodin, Yu V.; Dyadin, S. S.; Lyadenko, A. F.; Mashchenko, A. I.; Ul'yanov, I. A.; Fatin, Yu L.

1992-02-01

A passive ring resonator based on channel waveguides, formed in a K8 glass substrate by diffusion ion exchange in molten potassium nitrate, was made and investigated. The waveguide structure of the resonator included a ring waveguide as well as two Y-type couplers, whose symmetric arms were coupled to the ring waveguide, whereas homogeneous arms were coupled to an external laser and a photodetector. The coupling of the external devices to the channel waveguides was implemented by prisms and butt (end face) contacts. The transfer function of the ring resonator was determined experimentally in order to illustrate its resonant properties and sharpness. Estimates were obtained of the ultimate sensitivity of an optical gyroscope utilizing a ring resonator with the properties described above and ways of improving this sensitivity were analyzed.

Small slot waveguide rings for on-chip quantum optical circuits.

PubMed

Rotenberg, Nir; Türschmann, Pierre; Haakh, Harald R; Martin-Cano, Diego; Götzinger, Stephan; Sandoghdar, Vahid

2017-03-06

Nanophotonic interfaces between single emitters and light promise to enable new quantum optical technologies. Here, we use a combination of finite element simulations and analytic quantum theory to investigate the interaction of various quantum emitters with slot-waveguide rings. We predict that for rings with radii as small as 1.44 μm, with a Q-factor of 27,900, near-unity emitter-waveguide coupling efficiencies and emission enhancements on the order of 1300 can be achieved. By tuning the ring geometry or introducing losses, we show that realistic emitter-ring systems can be made to be either weakly or strongly coupled, so that we can observe Rabi oscillations in the decay dynamics even for micron-sized rings. Moreover, we demonstrate that slot waveguide rings can be used to directionally couple emission, again with near-unity efficiency. Our results pave the way for integrated solid-state quantum circuits involving various emitters.

The plasma environment, charge state, and currents of Saturn's C and D rings

NASA Technical Reports Server (NTRS)

Wilson, G. R.

1991-01-01

The charge state and associated currents of Saturn's C an D rings are studied by modeling the flow of ionospheric plasma from the mid- to low-latitude ionosphere to the vicinity of the rings. It is found that the plasma density near the C and D rings, at a given radial location, will experience a one to two order of magnitude diurnal variation. The surface charge density (SCD) of these rings can show significant radial and azimuthal variations due mainly to variation in the plasma density. The SCD also depends on structural features of the rings such as thickness and the nature of the particle size distribution. The associated azimuthal currents carried by these rings also show large diurnal variations resulting in field-aligned currents which close in the ionosphere. The resulting ionospheric electric field will probably not produce a significant amount of plasma convection in the topside ionosphere and inner plasmasphere.

Planning and Prototyping for a Storage Ring Measurement of the Proton Electric Dipole Moment

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

Talman, Richard

2015-07-01

Electron and proton EDM's can be measured in "frozen spin" (with the beam polarization always parallel to the orbit, for example) storage rings. For electrons the "magic" kinetic energy at which the beam can be frozen is 14.5 MeV. For protons the magic kinetic energy is 230 MeV. The currently measured upper limit for the electron EDM is much smaller than the proton EDM upper limit, which is very poorly known. Nevertheless, because the storage ring will be an order of magnitude cheaper, a sensible plan is to first build an all-electric electron storage ring as a prototype. Such anmore » electron ring was successfully built at Brookhaven, in 1954, as a prototype for their AGS ring. This leaves little uncertainty concerning the cost and performance of such a ring. (This is documentedin one of the Physical Review papers mentioned above.)« less

Vernier effect-based multiplication of the Sagnac beating frequency in ring laser gyroscope sensors

NASA Astrophysics Data System (ADS)

Adib, George A.; Sabry, Yasser M.; Khalil, Diaa

2018-02-01

A multiplication method of the Sagnac effect scale factor in ring laser gyroscopes is presented based on the Vernier effect of a dual-coupler passive ring resonator coupled to the active ring. The multiplication occurs when the two rings have comparable lengths or integer multiples and their scale factors have opposite signs. In this case, and when the rings have similar areas, the scale factor is multiplied by ratio of their length to their length difference. The scale factor of the presented configuration is derived analytically and the lock-in effect is analyzed. The principle is demonstrated using optical fiber rings and semiconductor optical amplifier as gain medium. A scale factor multiplication by about 175 is experimentally measured, demonstrating larger than two orders of magnitude enhancement in the Sagnac effect scale factor for the first time in literature, up to the authors' knowledge.

Relation of Nickel Concentrations in Tree Rings to Groundwater Contamination

NASA Astrophysics Data System (ADS)

Yanosky, Thomas M.; Vroblesky, Don A.

1992-08-01

Increment cores were collected from trees growing at two sites where groundwater is contaminated by nickel. Proton-induced X ray emission spectroscopy was used to determine the nickel concentrations in selected individual rings and in parts of individual rings. Ring nickel concentrations were interpreted on the basis of recent concentrations of nickel in aquifers, historical information about site use activities, and model simulations of groundwater flow. Nickel concentrations in rings increased during years of site use but not in trees outside the contaminated aquifers. Consequently, it was concluded that trees may preserve in their rings an annual record of nickel contamination in groundwater. Tulip trees and oaks contained higher concentrations of nickel than did sassafras, sweet gum, or black cherry. No evidence was found that nickel accumulates consistently within parts of individual rings or that nickel is translocated across ring boundaries.

Relation of nickel concentrations in tree rings to groundwater contamination

USGS Publications Warehouse

Yanosky, Thomas M.; Vroblesky, Don A.

1992-01-01

Increment cores were collected from trees growing at two sites where groundwater is contaminated by nickel. Proton-induced X ray emission spectroscopy was used to determine the nickel concentrations in selected individual rings and in parts of individual rings. Ring nickel concentrations were interpreted on the basis of recent concentrations of nickel in aquifers, historical information about site use activities, and model simulations of groundwater flow. Nickel concentrations in rings increased during years of site use but not in trees outside the contaminated aquifers. Consequently, it was concluded that trees may preserve in their rings an annual record of nickel contamination in groundwater. Tulip trees and oaks contained higher concentrations of nickel than did sassafras, sweet gum, or black cherry. No evidence was found that nickel accumulates consistently within parts of individual rings or that nickel is translocated across ring boundaries.

A Safe and Effective Modification of Thomson's Jumping Ring Experiment

ERIC Educational Resources Information Center

Waschke, Felix; Strunz, Andreas; Meyn, Jan-Peter

2012-01-01

The electrical circuit of the jumping ring experiment based on discharging a capacitor is optimized. The setup is scoop proof at 46 V and yet the ring jumps more than 9 m high. The setup is suitable for both lectures and student laboratory work in higher education. (Contains 1 table, 8 figures and 3 footnotes.)

Isotope signals and anatomical features in tree rings suggest a role for hydraulic strategies in diffuse drought-induced die-back of Pinus nigra.

PubMed

Petrucco, Laura; Nardini, Andrea; von Arx, Georg; Saurer, Matthias; Cherubini, Paolo

2017-04-01

The 2003 and 2012 summer seasons were among the warmest and driest of the last 200 years over southeastern Europe, and in particular in the Karst region (northeastern Italy). Starting from winter-spring 2013, several black pines (Pinus nigra J.F. Arnold) suffered crown die-back. Declining trees occurred nearby individuals with no signs of die-back, raising hypotheses about the occurrence of individual-specific hydraulic strategies underlying different responses to extreme drought. We investigated possible processes driving black pine decline by dendrochronological and wood anatomical measurements, coupled with analysis of tree-ring carbon (δ13C) and oxygen (δ18O) isotopic composition in healthy trees (H) and trees suffering die-back (D). Die-back trees showed higher growth rates than H trees at the beginning of the last century, but suffered important growth reduction following the dry summers in 2003 and 2012. After the 2012 drought, D trees produced tracheids with larger diameter and greater vulnerability to implosion than H ones. Healthy trees had significantly higher wood δ13C than D trees, reflecting higher water-use efficiency for the surviving trees, i.e., less water transpired per unit carbon gain, which could be related to lower stomatal conductance and a more conservative use of water. Relatively high δ18O for D trees indicates that they were strongly dependent on shallow water sources, or that they sustained higher transpiration rates than H trees. Our results suggest that H trees adopted a more conservative water-use strategy under drought stress compared with D trees. We speculate that this diversity might have a genotypic basis, but other possible explanations, like different rooting depth, cannot be ruled out. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A Theoretical and Experimental Study of Acoustic Propagation in Multisectioned Circular Ducts. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Wyerman, B. R.

1976-01-01

The propagation of plane waves and higher order acoustic modes in a circular multisectioned duct was studied. A unique source array consisting of two concentric rings of sources, providing phase and amplitude control in the radial, as well as circumferential direction, was developed to generate plane waves and both spinning and nonspinning higher order modes. Measurements of attenuation and radial mode shapes were taken with finite length liners inserted between the hard wall sections of an anechoically terminated duct. Materials tested as liners included a glass fiber material and both sintered fiber metals and perforated sheet metals with a honeycomb backing. The fundamental acoustic properties of these materials were studied with emphasis on the attenuation of sound by the liners and the determination of local versus extended reaction behavior for the boundary condition. A search technique was developed to find the complex eigenvalues for a liner under the assumption of a locally reacting boundary condition.

An Archetype Semi-Ring Fabry-Perot (SRFP) Resonator

NASA Technical Reports Server (NTRS)

Taghavi-Larigani, Shervin; VanZyl, Jakob

2009-01-01

We introduce and demonstrate the generation of a novel resonator, termed Semi-Ring Fabry-Perot (SRFP), that exhibits unique features, such as, its use of one plane mirror, allowing the SRFP to be easily fabricated as a symmetrical device. In addition to its unique features, it exhibits advantages of ring and Fabry-Perot resonators: 1) compared to a ring resonator that only allows a transmitted intensity, the Semi-Ring Fabry-Perot (SRFP) supports standing waves, allowing both a reflected and transmitted intensity; 2) the reflected light spectrum of the SRFP resonator is much narrower than similar Fabry-Perot, implying higher finesse.

Levitation pressure and friction losses in superconducting bearings

DOEpatents

Hull, John R.

2001-01-01

A superconducting bearing having at least one permanent magnet magnetized with a vertical polarization. The lower or stator portion of the bearing includes an array of high-temperature superconducting elements which are comprised of a plurality of annular rings. An annular ring is located below each permanent magnet and an annular ring is offset horizontally from at least one of the permanent magnets. The rings are composed of individual high-temperature superconducting elements located circumferentially along the ring. By constructing the horizontally-offset high-temperature superconducting ring so that the c-axis is oriented in a radial direction, a higher levitation force can be achieved. Such an orientation will also provide substantially lower rotational drag losses in the bearing.

Topology and entanglement in quench dynamics

NASA Astrophysics Data System (ADS)

Chang, Po-Yao

2018-06-01

We classify the topology of the quench dynamics by homotopy groups. A relation between the topological invariant of a postquench order parameter and the topological invariant of a static Hamiltonian is shown in d +1 dimensions (d =1 ,2 ,3 ). The midgap states in the entanglement spectrum of the postquench states reveal their topological nature. When a trivial quantum state is under a sudden quench to a Chern insulator, the midgap states in the entanglement spectrum form rings. These rings are analogous to the boundary Fermi rings in the Hopf insulators. Finally, we show a postquench order parameter in 3+1 dimensions can be characterized by the second Chern number. The number of Dirac cones in the entanglement spectrum is equal to the second Chern number.

Rational harmonic mode-locking pulse quality of the dark-optical-comb injected semiconductor optical amplifier fiber ring laser.

PubMed

Lin, Gong-Ru; Lee, Chao-Kuei; Kang, Jung-Jui

2008-06-09

We study the rational harmonic mode-locking (RHML) order dependent pulse shortening force and dynamic chirp characteristics of a gain-saturated semiconductor optical amplifier fiber laser (SOAFL) under dark-optical-comb injection, and discuss the competition between mode-locking mechanisms in the SOAFL at high-gain and strong optical injection condition at higher RHML orders. The evolutions of spectra, mode-locking and continuous lasing powers by measuring the ratio of DC/pulse amplitude and the pulse shortening force (I(pulse)/P(avg)(2) ) are performed to determine the RHML capability of SOAFL. As the rational harmonic order increases up to 20, the spectral linewidth shrinks from 12 to 3 nm, the ratio of DC/pulse amplitude enlarges from 0.025 to 2.4, and the pulse-shortening force reduces from 0.9 to 0.05. At fundamental and highest RHML condition, we characterize the frequency detuning range to realize the mode-locking quality, and measure the dynamic frequency chirp of the RHML-SOAFL to distinguish the linear and nonlinear chirp after dispersion compensation. With increasing RHML order, the pulsewidth is broadened from 4.2 to 26.4 ps with corresponding chirp reducing from 0.7 to 0.2 GHz and linear/nonlinear chirp ratio changes from 4.3 to 1.3, which interprets the high-order chirp becomes dominates at higher RHML orders.

Boomerang Satellites

NASA Astrophysics Data System (ADS)

Hesselbrock, Andrew; Minton, David A.

2017-10-01

We recently reported that the orbital architecture of the Martian environment allows for material in orbit around the planet to ``cycle'' between orbiting the planet as a ring, or as coherent satellites. Here we generalize our previous analysis to examine several factors that determine whether satellites accreting at the edge of planetary rings will cycle. In order for the orbiting material to cycle, tidal evolution must decrease the semi-major axis of any accreting satellites. In some systems, the density of the ring/satellite material, the surface mass density of the ring, the tidal parameters of the system, and the rotation rate of the primary body contribute to a competition between resonant ring torques and tidal dissipation that prevent this from occurring, either permanently or temporarily. Analyzing these criteria, we examine various bodies in our solar system (such as Saturn, Uranus, and Eris) to identify systems where cycling may occur. We find that a ring-satellite cycle may give rise to the current Uranian ring-satellite system, and suggest that Miranda may have formed from an early, more massive Uranian ring.

Revegetation of the riparian zone of the Three Gorges Dam Reservoir leads to increased soil bacterial diversity.

PubMed

Ren, Qingshui; Li, Changxiao; Yang, Wenhang; Song, Hong; Ma, Peng; Wang, Chaoying; Schneider, Rebecca L; Morreale, Stephen J

2018-06-06

As one of the most active components in soil, bacteria can affect soil physicochemical properties, its biological characteristics, and even its quality and health. We characterized dynamics of the soil bacterial diversity in planted (with Taxodium distichum) and unplanted soil in the riparian zone of the Three Gorges Dam Reservoir (TGDR), in southwestern China, in order to accurately quantify the changes in long-term soil bacterial community structure after revegetation. Measurements were taken annually in situ in the TGDR over the course of 5 years, from 2012 to 2016. Soil chemical properties and bacterial diversity were analyzed in both the planted and unplanted soil. After revegetation, the soil chemical properties in planted soil were significantly different than in unplanted soil. The effects of treatment, time, and the interaction of both time and treatment had significant impacts on most diversity indices. Specifically, the bacterial community diversity indices in planted soil were significantly higher and more stable than that in unplanted soil. The correlation analyses indicated that the diversity indices correlated with the pH value, organic matter, and soil available nutrients. After revegetation in the riparian zone of the TGDR, the soil quality and health is closely related to the observed bacterial diversity, and a higher bacterial diversity avails the maintenance of soil functionality. Thus, more reforestation should be carried out in the riparian zone of the TGDR, so as to effectively mitigate the negative ecological impacts of the dam. Vegetating the reservoir banks with Taxodium distichum proved successful, but planting mixed stands of native tree species could promote even higher riparian soil biodiversity and improved levels of ecosystem functioning within the TGDR.

Characterization of microwave plasma in a multicusp using 2D emission based tomography: Bessel modes and wave absorption

NASA Astrophysics Data System (ADS)

Rathore, Kavita; Bhattacharjee, Sudeep; Munshi, Prabhat

2017-06-01

A tomographic method based on the Fourier transform is used for characterizing a microwave plasma in a multicusp (MC), in order to obtain 2D distribution of plasma emissions, plasma (electron) density (Ne) and temperature (Te). The microwave plasma in the MC is characterized as a function of microwave power, gas pressure, and axial distance. The experimentally obtained 2D emission profiles show that the plasma emissions are generated in a circular ring shape. There are usually two bright rings, one at the plasma core and another near the boundary. The experimental results are validated using a numerical code that solves Maxwell's equations inside a waveguide filled with a plasma in a magnetic field, with collisions included. It is inferred that the dark and bright circular ring patterns are a result of superposition of Bessel modes (TE11 and TE21) of the wave electric field inside the plasma filled MC, which are in reasonable agreement with the plasma emission profiles. The tomographically obtained Ne and Te profiles indicate higher densities in the plasma core (˜1010 cm-3) and enhanced electron temperature in the ECR region (˜13 eV), which are in agreement with earlier results using a Langmuir probe and optical emission spectroscopy (OES) diagnostics.

Investigation of a Tricarbide Grooved Ring Fuel Element for a Nuclear Thermal Rocket

NASA Technical Reports Server (NTRS)

Taylor, Brian D.; Emrich, Bill; Tucker, Dennis; Barnes, Marvin; Donders, Nicolas; Benensky, Kelsa

2017-01-01

Deep space exploration, especially that of Mars, is on the horizon as the next big challenge for space exploration. Nuclear propulsion, through which high thrust and efficiency can be achieved, is a promising option for decreasing the cost and logistics of such a mission. Work on nuclear thermal engines goes back to the days of the NERVA program. Currently, nuclear thermal propulsion is under development again in various forms to provide a superior propulsion system for deep space exploration. The authors have been working to develop a concept nuclear thermal engine that uses a grooved ring fuel element as an alternative to the traditional hexagonal rod design. The authors are also studying the use of carbide fuels. The concept was developed in order to increase surface area and heat transfer to the propellant. The use of carbides would also raise the temperature limitations of the reactor. It is hoped that this could lead to a higher thrust to weight nuclear thermal engine. This paper describes the modeling of neutronics, heat transfer, and fluid dynamics of this alternative nuclear fuel element geometry. Fabrication experiments of grooved rings from carbide refractory metals are also presented along with material characterization and interactions with a hot hydrogen environment.

Structural pathway of regulated substrate transfer and threading through an Hsp100 disaggregase.

PubMed

Deville, Célia; Carroni, Marta; Franke, Kamila B; Topf, Maya; Bukau, Bernd; Mogk, Axel; Saibil, Helen R

2017-08-01

Refolding aggregated proteins is essential in combating cellular proteotoxic stress. Together with Hsp70, Hsp100 chaperones, including Escherichia coli ClpB, form a powerful disaggregation machine that threads aggregated polypeptides through the central pore of tandem adenosine triphosphatase (ATPase) rings. To visualize protein disaggregation, we determined cryo-electron microscopy structures of inactive and substrate-bound ClpB in the presence of adenosine 5'- O -(3-thiotriphosphate), revealing closed AAA+ rings with a pronounced seam. In the substrate-free state, a marked gradient of resolution, likely corresponding to mobility, spans across the AAA+ rings with a dynamic hotspot at the seam. On the seam side, the coiled-coil regulatory domains are locked in a horizontal, inactive orientation. On the opposite side, the regulatory domains are accessible for Hsp70 binding, substrate targeting, and activation. In the presence of the model substrate casein, the polypeptide threads through the entire pore channel and increased nucleotide occupancy correlates with higher ATPase activity. Substrate-induced domain displacements indicate a pathway of regulated substrate transfer from Hsp70 to the ClpB pore, inside which a spiral of loops contacts the substrate. The seam pore loops undergo marked displacements, along with ordering of the regulatory domains. These asymmetric movements suggest a mechanism for ATPase activation and substrate threading during disaggregation.

Comparing contractile apparatus-driven cytokinesis mechanisms across kingdoms.

PubMed

Balasubramanian, Mohan K; Srinivasan, Ramanujam; Huang, Yinyi; Ng, Kian-Hong

2012-11-01

Cytokinesis is the final stage of the cell cycle during which a cell physically divides into two daughters through the assembly of new membranes (and cell wall in some cases) between the forming daughters. New membrane assembly can either proceed centripetally behind a contractile apparatus, as in the case of prokaryotes, archaea, fungi, and animals or expand centrifugally, as in the case of higher plants. In this article, we compare the mechanisms of cytokinesis in diverse organisms dividing through the use of a contractile apparatus. While an actomyosin ring participates in cytokinesis in almost all centripetally dividing eukaryotes, the majority of bacteria and archaea (except Crenarchaea) divide using a ring composed of the tubulin-related protein FtsZ. Curiously, despite molecular conservation of the division machinery components, division site placement and its cell cycle regulation occur by a variety of unrelated mechanisms even among organisms from the same kingdom. While molecular motors and cytoskeletal polymer dynamics contribute to force generation during eukaryotic cytokinesis, cytoskeletal polymer dynamics alone appears to be sufficient for force generation during prokaryotic cytokinesis. Intriguingly, there are life forms on this planet that appear to lack molecules currently known to participate in cytokinesis and how these cells perform cytokinesis remains a mystery waiting to be unravelled. Copyright © 2012 Wiley Periodicals, Inc.

Variability in spatial and temporal occurrence of presettlement and settlement-stage fishes associated with shallow reefs.

PubMed

Pattrick, P; Strydom, N A

2017-03-01

Presettlement and settlement-stage fishes were studied in a large, log-spiral bay in temperate South Africa. The aim was to describe the assemblage composition, density and distribution associated with four types of habitats common to the bay: high profile reef, low profile reef, reef-associated sand and open sand spatially separated from reef. Samples were collected with both a plankton ring net and a light trap at each habitat type as part of a mixed-method approach. A total of 4084 presettlement and settlement-stage fishes belonging to 31 teleost families and 84 species were captured. Reef-associated sand and open sand habitats yielded higher species richness and diversity than the high and low-profile reef habitats. Engraulidae, Gobiidae, Clupeidae and Cynoglossidae were the dominant fish families captured with the ring net, while Engraulidae, Clupeidae, Carangidae and Clinidae were captured with the light trap. A temporal difference in the abundance of presettlement fishes occurred between the sampling periods with highest values recorded during the summer settlement period. Habitat type together with associated physico-chemical variables played a pivotal role in determining presettlement fish species composition, density and distribution across habitat types. © 2016 The Fisheries Society of the British Isles.

Hybrid Methods Reveal Multiple Flexibly Linked DNA Polymerases within the Bacteriophage T7 Replisome

DOE PAGES

Wallen, Jamie R.; Zhang, Hao; Weis, Caroline; ...

2017-01-03

The physical organization of DNA enzymes at a replication fork enables efficient copying of two antiparallel DNA strands, yet dynamic protein interactions within the replication complex complicate replisome structural studies. We employed a combination of crystallographic, native mass spectrometry and small-angle X-ray scattering experiments to capture alternative structures of a model replication system encoded by bacteriophage T7. then, the two molecules of DNA polymerase bind the ring-shaped primase-helicase in a conserved orientation and provide structural insight into how the acidic C-terminal tail of the primase-helicase contacts the DNA polymerase to facilitate loading of the polymerase onto DNA. A third DNA polymerasemore » binds the ring in an offset manner that may enable polymerase exchange during replication. Alternative polymerase binding modes are also detected by small-angle X-ray scattering with DNA substrates present. The collective results unveil complex motions within T7 replisome higher-order structures that are underpinned by multivalent protein-protein interactions with functional implications.« less

Hybrid Methods Reveal Multiple Flexibly Linked DNA Polymerases within the Bacteriophage T7 Replisome

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

Wallen, Jamie R.; Zhang, Hao; Weis, Caroline

The physical organization of DNA enzymes at a replication fork enables efficient copying of two antiparallel DNA strands, yet dynamic protein interactions within the replication complex complicate replisome structural studies. We employed a combination of crystallographic, native mass spectrometry and small-angle X-ray scattering experiments to capture alternative structures of a model replication system encoded by bacteriophage T7. then, the two molecules of DNA polymerase bind the ring-shaped primase-helicase in a conserved orientation and provide structural insight into how the acidic C-terminal tail of the primase-helicase contacts the DNA polymerase to facilitate loading of the polymerase onto DNA. A third DNA polymerasemore » binds the ring in an offset manner that may enable polymerase exchange during replication. Alternative polymerase binding modes are also detected by small-angle X-ray scattering with DNA substrates present. The collective results unveil complex motions within T7 replisome higher-order structures that are underpinned by multivalent protein-protein interactions with functional implications.« less

Immobile myosin-II plays a scaffolding role during cytokinesis in budding yeast

PubMed Central

Wloka, Carsten; Vallen, Elizabeth A.; Thé, Lydia; Fang, Xiaodong; Oh, Younghoon

2013-01-01

Core components of cytokinesis are conserved from yeast to human, but how these components are assembled into a robust machine that drives cytokinesis remains poorly understood. In this paper, we show by fluorescence recovery after photobleaching analysis that Myo1, the sole myosin-II in budding yeast, was mobile at the division site before anaphase and became immobilized shortly before cytokinesis. This immobility was independent of actin filaments or the motor domain of Myo1 but required a small region in the Myo1 tail that is thought to be involved in higher-order assembly. As expected, proteins involved in actin ring assembly (tropomyosin and formin) and membrane trafficking (myosin-V and exocyst) were dynamic during cytokinesis. Strikingly, proteins involved in septum formation (the chitin synthase Chs2) and/or its coordination with the actomyosin ring (essential light chain, IQGAP, F-BAR, etc.) displayed Myo1-dependent immobility during cytokinesis, suggesting that Myo1 plays a scaffolding role in the assembly of a cytokinesis machine. PMID:23358243

Substitution and solvent effects in the chalcones isomerization barrier of flavylium photochromic systems.

PubMed

Roque, Ana; Lima, João Carlos; Parola, A Jorge; Pina, Fernando

2007-04-01

Useful application of photochromic compounds as optical memories implies the existence of a large kinetic barrier between the forms interconverted by light. In the case of flavylium salts, the ground state isomerization barrier between the photoisomerizable chalcone isomers is shown to correlate with the electron donating ability of the substituents, measured by their effects in the (1)H NMR chemical shifts of the aromatic protons. Substitution with electron donating groups in ring A lowers the barrier while substitution at ring B has the opposite effect. However, in water, the observed increase is higher than expected in the case of compound 4',9-dihydroxychalcone when compared with the analogous 4'-dimethylamino-9-hydroxychalcone, containing a better electron donating group in the same position. Our interpretation is that the water network is providing an efficient pathway to form tautomers. In acetonitrile, unlike water, the expected order is indeed observed: E(a)(4',9-dihydroxychalcone) = 60 kJ mol(-1) < E(a) (4'-dimethylamino-9-hydroxychalcone) = 69 kJ mol(-1).

Photon hopping and nanowire based hybrid plasmonic waveguide and ring-resonator

PubMed Central

Gu, Zhiyuan; Liu, Shuai; Sun, Shang; Wang, Kaiyang; Lyu, Quan; Xiao, Shumin; Song, Qinghai

2015-01-01

Nanowire based hybrid plasmonic structure plays an important role in achieving nanodevices, especially for the wide band-gap materials. However, the conventional schemes of nanowire based devices such as nano-resonators are usually isolated from the integrated nano-network and have extremely low quality (Q) factors. Here we demonstrate the transmission of waves across a gap in hybrid plasmonic waveguide, which is termed as “photon hopping”. Based on the photon hopping, we show that the emissions from nanodevices can be efficiently collected and conducted by additional nanowires. The collection ratio can be higher than 50% for a wide range of separation distance, transverse shift, and tilt. Moreover, we have also explored the possibility of improving performances of individual devices by nano-manipulating the nanowire to a pseudo-ring. Our calculations show that both Q factor and Purcell factor have been increased by more than an order of magnitude. We believe that our researches will be essential to forming nanolasers and the following nano-networks.

Optical Add-Drop Filters Based on Photonic Crystal Ring Resonators

DTIC Science & Technology

2007-02-19

34 Appl. Phys. Lett. 81,2499-2501 (2002). 17. V. Dinesh Kumar , T. Srinivas, A. Selvarajan, "Investigation of ring resonators in photonic crystal...No.4 / opncs EXPRESS 1824 Kumar et al. [17], where a large single quasi-rectangular ring was introduced as the frequency selective dropping elements...were introduced by Kumar et al. as well, in order to suppress the counter propagating modes which can cause spurious dips in the transmission spectrum

Long-Lived Pure Electron Plasma in Ring Trap-1

NASA Astrophysics Data System (ADS)

Saitoh, Haruhiko; Yoshida, Zensho; Morikawa, Junji; Watanabe, Sho; Yano, Yoshihisa; Suzuki, Junko

The Ring Trap-1 (RT-1) experiment succeeded in producing a long-lived (of the order 102 s), stable, non-neutral (pure electron) plasma. Electrons are confined by a magnetospheric dipole field. To eliminate a loss channel of the plasmas caused by support structures, a superconducting coil was magnetically levitated. This coil levitation drastically improved the confinement properties of the electron plasma compared to previous Prototype-Ring Trap (Proto-RT) experiments.

3-(2-Biphenyl)sydnone

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

Riddle, Gordon B.; Grossie, David A.; Turnbull, Kenneth

2010-11-16

The title compound, C{sub 14}H{sub 10}N{sub 2}O{sub 2}, is one of many sydnones which have been synthesized in order to investigate the influence of substituents and sydnone-ring stability. There is medicinal interest in the sydnone if the ring can predictably release NO. Bond lengths and angles of the sydnone ring were compared with those of other published sydnone compounds and were found to fit the average of the published data.

The use of silicone based adhesives to encapsulate manganin gauges for high stress experiments

NASA Astrophysics Data System (ADS)

Be'Ery, Ilan; Rosenberg, Zvi

2007-06-01

The use of commercial manganin stress gauges has been limited to stresses in the range of 0-20 GPa due to the short-circuiting of their encapsulating materials (epoxy, Kapton) at higher pressures. Researchers at Lawrence Livermore overcome this difficulty by embedding their gauges in Teflon sheets and measured shock pressures as high as 40 GPa. The fact that Teflon can keep its resistivity at high pressures is attributed to the lack of benzene rings in its structure. On the other hand, Teflon is difficult to work with as an encapsulating material because of its poor adhesive properties. In order to overcome this difficulty we encapsulated our foils in between two tapes of Teflon which have a silicone adhesive glued to it. These are 50 μm thick commercial tapes (manufactured by 3M, type #60) which have a 50 μm thick silicone adhesive (PSA -- pressure sensitive adhesive) on them. This adhesive is easy to work with, has no benzene rings in its structure and has a lower carbon content, compared to other adhesives. Several experiments were conducted in order to directly measure the resistivity of these tapes at high pressures, as well as using them to encapsulate our manganin foils for high pressure studies.

Modeling and analysis of a microresonating biosensor for detection of Salmonella bacteria in human blood.

PubMed

Bahadoran, Mahdi; Noorden, Ahmad Fakhrurrazi Ahmad; Chaudhary, Kashif; Mohajer, Faeze Sadat; Aziz, Muhammad Safwan; Hashim, Shahrin; Ali, Jalil; Yupapin, Preecha

2014-07-18

A new photonics biosensor configuration comprising a Double-side Ring Add-drop Filter microring resonator (DR-ADF) made from SiO2-TiO2 material is proposed for the detection of Salmonella bacteria (SB) in blood. The scattering matrix method using inductive calculation is used to determine the output signal's intensities in the blood with and without presence of Salmonella. The change in refractive index due to the reaction of Salmonella bacteria with its applied antibody on the flagellin layer loaded on the sensing and detecting microresonator causes the increase in through and dropper port's intensities of the output signal which leads to the detection of SB in blood. A shift in the output signal wavelength is observed with resolution of 0.01 nm. The change in intensity and shift in wavelength is analyzed with respect to the change in the refractive index which contributes toward achieving an ultra-high sensitivity of 95,500 nm/RIU which is almost two orders higher than that of reported from single ring sensors and the limit of detection is in the order of 1 × 10(-8) RIU. In applications, such a system can be employed for a high sensitive and fast detection of bacteria.

Modeling and Analysis of a Microresonating Biosensor for Detection of Salmonella Bacteria in Human Blood

PubMed Central

Bahadoran, Mahdi; Noorden, Ahmad Fakhrurrazi Ahmad; Chaudhary, Kashif; Mohajer, Faeze Sadat; Aziz, Muhammad Safwan; Hashim, Shahrin; Ali, Jalil; Yupapin, Preecha

2014-01-01

A new photonics biosensor configuration comprising a Double-side Ring Add-drop Filter microring resonator (DR-ADF) made from SiO2-TiO2 material is proposed for the detection of Salmonella bacteria (SB) in blood. The scattering matrix method using inductive calculation is used to determine the output signal's intensities in the blood with and without presence of Salmonella. The change in refractive index due to the reaction of Salmonella bacteria with its applied antibody on the flagellin layer loaded on the sensing and detecting microresonator causes the increase in through and dropper port's intensities of the output signal which leads to the detection of SB in blood. A shift in the output signal wavelength is observed with resolution of 0.01 nm. The change in intensity and shift in wavelength is analyzed with respect to the change in the refractive index which contributes toward achieving an ultra-high sensitivity of 95,500 nm/RIU which is almost two orders higher than that of reported from single ring sensors and the limit of detection is in the order of 1 × 10−8 RIU. In applications, such a system can be employed for a high sensitive and fast detection of bacteria. PMID:25046015

Measurements of three-dimensional shape and sound-induced motion of the chinchilla tympanic membrane

PubMed Central

Rosowski, John J; Dobrev, Ivo; Khaleghi, Morteza; Lu, Weina; Cheng, Jeffrey Tao; Harrington, Ellery; Furlong, Cosme

2013-01-01

Opto-electronic computer holographic measurements were made of the tympanic membrane (TM) in cadaveric chinchillas. Measurements with two laser wavelengths were used to compute the 3D-shape of the TM. Single laser wavelength measurements locked to eight distinct phases of a tonal stimulus were used to determine the magnitude and the relative phase of the surface displacements. These measurements were made at over 250,000 points on the TM surface. The measured motions contained spatial phase variations consistent with relatively low-order (large spatial frequency) modal motions and smaller magnitude higher-order (smaller spatial frequency) motions that appear to travel, but may also be explained by losses within the membrane. The measurement of shape and thin shell theory allowed us to separate the measured motions into those components orthogonal to the plane of the tympanic ring, and those components within the plane of the tympanic ring based on the 3D-shape. The predicted in-plane motion components are generally smaller than the out-of-plane perpendicular component of motion. Since the derivation of in-plane and out-of plane depended primarily on the membrane shape, the relative sizes of the predicted motion components did not vary with frequency. PMID:23247058

Design, Sustainable Synthesis, and Programmed Reactions of Templated N-Heteroaryl-Fused Vinyl Sultams.

PubMed

Laha, Joydev K; Sharma, Shubhra; Kirar, Seema; Banerjee, Uttam C

2017-09-15

A de novo design and synthesis of N-heteroaryl-fused vinyl sultams as templates for programming chemical reactions on vinyl sultam periphery or (hetero)aryl ring is described. The key features include rational designing and sustainable synthesis of the template, customized reactions of vinyl sultams at C═C bond or involving N-S bond cleavage, and reactions on the periphery of the heteroaryl ring for late-stage diversification. The simple, easy access to the template coupled with opportunities for the synthesis of diversely functionalized heterocyles from a single template constitutes a rare study in contemporary organic synthesis.

Production Of Hydroxylated Fatty Acids In Genetically Modified Plants

DOEpatents

Hall, David R.; Fox, Joe

2002-05-21

An annular wire harness for use in drill pipe comprising two rings interconnected by one or more insulated conductors. The rings are positioned within annular grooves located within the tool joints and the conductors are fixed within grooves along the bore wall of the pipe. The rings may be recessed within annular grooves in order to permit refacing of the tool joint. The rings are provided with means for coupling a power and data signal from an adjacent pipe to the conductors in such a fashion that the signal may be transmitted along the drill pipe and along an entire drill string.

Compact Storage Ring for an X-Ray Source

NASA Astrophysics Data System (ADS)

Ovchinnikova, L.; Shvedunov, V.; Ivanov, K.

2017-12-01

We propose a new design of a compact storage ring for a source of X-ray radiation on the basis of reverse Thomson scattering of laser radiation by electrons with the energy of 35-50 MeV, which has small number of optical elements and a significant clear space for the placement of a beam injection-extraction system and a RF cavity. The original laser cavity layout has been considered. The ring dynamic aperture after correction of chromaticity and a second-order dispersion function is sufficient for the injection and stable circulation of an electron bunch in the ring.

[Effects of revegetation approach and terrain on plant species diversity as a result of converting croplands to forests in the Loess region of western Shanxi Province, China].

PubMed

Wu, Wen Juan; Zha, Tong Gang; Zhang, Zhi Qiang

2017-04-18

The plant species diversity of stands converted from croplands as affected by revegetation approaches and terrains was studied using the transect line plot sampling. The goal of the study was to provide reference for evaluation reforestation effects and forest management in the Loess region of western Shanxi Province. The results showed that revegetation approach had a great influence on plant species diversity in stands. The number of species in the natural restoration forest (NF) was 1.6 times of that of Robinia pseudoacacia plantation (RP), the Shannon index of NF was higher, and the Pielou index of NF was lower. Slope position had significant effect on the species diversity, and the three species diversity indices were all in order of bottom of loess gully > middle slope of loess gully > slope of loess hill > top of loess hill. The species diversity indices on the shady slope were higher than those on the sunny slope, while the difference was not significant. Integrated effects of terrain and revegetation approach had significant influences on species diversity. The species diversity was highest at the bottom of shady slope of NF, and the species evenness was highest at the bottom of shady slope of RP. For improving the species diversity, the afforestation design in the Loess area must consider terrain position and the natural forest recovery process following the principle of 'selecting suitable tree species for the right site'.

Accurate and diverse recommendations via eliminating redundant correlations

NASA Astrophysics Data System (ADS)

Zhou, Tao; Su, Ri-Qi; Liu, Run-Ran; Jiang, Luo-Luo; Wang, Bing-Hong; Zhang, Yi-Cheng

2009-12-01

In this paper, based on a weighted projection of a bipartite user-object network, we introduce a personalized recommendation algorithm, called network-based inference (NBI), which has higher accuracy than the classical algorithm, namely collaborative filtering. In NBI, the correlation resulting from a specific attribute may be repeatedly counted in the cumulative recommendations from different objects. By considering the higher order correlations, we design an improved algorithm that can, to some extent, eliminate the redundant correlations. We test our algorithm on two benchmark data sets, MovieLens and Netflix. Compared with NBI, the algorithmic accuracy, measured by the ranking score, can be further improved by 23 per cent for MovieLens and 22 per cent for Netflix. The present algorithm can even outperform the Latent Dirichlet Allocation algorithm, which requires much longer computational time. Furthermore, most previous studies considered the algorithmic accuracy only; in this paper, we argue that the diversity and popularity, as two significant criteria of algorithmic performance, should also be taken into account. With more or less the same accuracy, an algorithm giving higher diversity and lower popularity is more favorable. Numerical results show that the present algorithm can outperform the standard one simultaneously in all five adopted metrics: lower ranking score and higher precision for accuracy, larger Hamming distance and lower intra-similarity for diversity, as well as smaller average degree for popularity.

Color-pattern analysis of eyespots in butterfly wings: a critical examination of morphogen gradient models.

PubMed

Otaki, Joji M

2011-06-01

Butterfly wing color patterns consist of many color-pattern elements such as eyespots. It is believed that eyespot patterns are determined by a concentration gradient of a single morphogen species released by diffusion from the prospective eyespot focus in conjunction with multiple thresholds in signal-receiving cells. As alternatives to this single-morphogen model, more flexible multiple-morphogen model and induction model can be proposed. However, the relevance of these conceptual models to actual eyespots has not been examined systematically. Here, representative eyespots from nymphalid butterflies were analyzed morphologically to determine if they are consistent with these models. Measurement of ring widths of serial eyespots from a single wing surface showed that the proportion of each ring in an eyespot is quite different among homologous rings of serial eyespots of different sizes. In asymmetric eyespots, each ring is distorted to varying degrees. In extreme cases, only a portion of rings is expressed remotely from the focus. Similarly, there are many eyespots where only certain rings are deleted, added, or expanded. In an unusual case, the central area of an eyespot is composed of multiple "miniature eyespots," but the overall macroscopic eyespot structure is maintained. These results indicate that each eyespot ring has independence and flexibility to a certain degree, which is less consistent with the single-morphogen model. Considering a "periodic eyespot", which has repeats of a set of rings, damage-induced eyespots in mutants, and a scale-size distribution pattern in an eyespot, the induction model is the least incompatible with the actual eyespot diversity.

ERBE S7 NAT

Atmospheric Science Data Center

2016-06-15

... detectors continuously view the earth disc (plus a small ring of space). The measurements are continuous over the entire globe for ... Page SCAR-B G8 FIRE Order Data: ASDC Order Tool:  Order Data ...

ERBE S8 NAT

Atmospheric Science Data Center

2016-06-15

... detectors continuously view the earth disc (plus a small ring of space). The measurements are continuous over the entire globe for ... Page SCAR-B G8 FIRE Order Data: ASDC Order Tool:  Order Data ...

"Academicus Interculturalis"? Negotiating Interculturality in Academic Communities of Practice

ERIC Educational Resources Information Center

Otten, Matthias

2009-01-01

Structure and agency of cultural diversity in (international) higher education have to be addressed with a critical perspective on international mobility and practices of international academic teaching. In order to overcome naive assumptions about intercultural developments on the individual and the organizational level, sociological analysis…

Fiber-optic annular detector array for large depth of field photoacoustic macroscopy.

PubMed

Bauer-Marschallinger, Johannes; Höllinger, Astrid; Jakoby, Bernhard; Burgholzer, Peter; Berer, Thomas

2017-03-01

We report on a novel imaging system for large depth of field photoacoustic scanning macroscopy. Instead of commonly used piezoelectric transducers, fiber-optic based ultrasound detection is applied. The optical fibers are shaped into rings and mainly receive ultrasonic signals stemming from the ring symmetry axes. Four concentric fiber-optic rings with varying diameters are used in order to increase the image quality. Imaging artifacts, originating from the off-axis sensitivity of the rings, are reduced by coherence weighting. We discuss the working principle of the system and present experimental results on tissue mimicking phantoms. The lateral resolution is estimated to be below 200 μm at a depth of 1.5 cm and below 230 μm at a depth of 4.5 cm. The minimum detectable pressure is in the order of 3 Pa. The introduced method has the potential to provide larger imaging depths than acoustic resolution photoacoustic microscopy and an imaging resolution similar to that of photoacoustic computed tomography.

Scaffold Diversity Synthesis Delivers Complex, Structurally, and Functionally Distinct Tetracyclic Benzopyrones

PubMed Central

Sankar, Muthukumar G.; Roy, Sayantani; Tran, Tuyen Thi Ngoc; Wittstein, Kathrin; Bauer, Jonathan O.; Strohmann, Carsten; Ziegler, Slava

2018-01-01

Abstract Complexity‐generating chemical transformations that afford novel molecular scaffolds enriched in sp 3 character are highly desired. Here, we present a highly stereoselective scaffold diversity synthesis approach that utilizes cascade double‐annulation reactions of diverse pairs of zwitterionic and non‐zwitterionic partners with 3‐formylchromones to generate highly complex tetracyclic benzopyrones. Each pair of annulation partners adds to the common chroman‐4‐one scaffold to build two new rings, supporting up to four contiguous chiral centers that include an all‐carbon quaternary center. Differently ring‐fused benzopyrones display different biological activities, thus demonstrating their immense potential in medicinal chemistry and chemical biology research. PMID:29721402

Hybrid plasmonic waveguide-assisted Metal–Insulator–Metal ring resonator for refractive index sensing

NASA Astrophysics Data System (ADS)

Butt, M. A.; Khonina, S. N.; Kazanskiy, N. L.

2018-05-01

A highly sensitive refractive index sensor based on an integrated hybrid plasmonic waveguide (HPWG) and a Metal-Insulator-Metal (M-I-M) micro-ring resonator is presented. In our design, there are two slot-waveguide-based micro-rings that encircle a gold disc. The outer slot WG is formed by the combination of Silicon-Air-Gold ring and the inner slot-waveguide is formed by Gold ring-Air-Gold disc. The slot-waveguide rings provide an interaction length sufficient to accumulate a detectable wavelength shift. The transmission spectrum and electric field distribution of this sensor structure are simulated using Finite Element Method (FEM). The sensitivity of this micro-ring resonator is achieved at 800 nm/RIU which is about six times higher than that of the conventional Si ring with the same geometry. Our proposed sensor design has a potential to find further applications in biomedical science and nano-photonic circuits.

Vortex rings impinging on permeable boundaries

NASA Astrophysics Data System (ADS)

Mujal-Colilles, Anna; Dalziel, Stuart B.; Bateman, Allen

2015-01-01

Experiments with vortex rings impinging permeable and solid boundaries are presented in order to investigate the influence of permeability. Utilizing Particle Image Velocimetry, we compared the behaviour of a vortex ring impinging four different reticulated foams (with permeability k ˜ 26 - 85 × 10-8 m2) and a solid boundary. Results show how permeability affects the stretching phenomena of the vortex ring and the formation and evolution of the secondary vortex ring with opposite sign. Moreover, permeability also affects the macroscopic no-slip boundary condition found on the solid boundary, turning it into an apparent slip boundary condition for the most permeable boundary. The apparent slip-boundary condition and the flux exchange between the ambient fluid and the foam are jointly responsible for both the modified formation of the secondary vortex and changes on the vortex ring diameter increase.

Experimental characterization of a quantum many-body system via higher-order correlations.

PubMed

Schweigler, Thomas; Kasper, Valentin; Erne, Sebastian; Mazets, Igor; Rauer, Bernhard; Cataldini, Federica; Langen, Tim; Gasenzer, Thomas; Berges, Jürgen; Schmiedmayer, Jörg

2017-05-17

Quantum systems can be characterized by their correlations. Higher-order (larger than second order) correlations, and the ways in which they can be decomposed into correlations of lower order, provide important information about the system, its structure, its interactions and its complexity. The measurement of such correlation functions is therefore an essential tool for reading, verifying and characterizing quantum simulations. Although higher-order correlation functions are frequently used in theoretical calculations, so far mainly correlations up to second order have been studied experimentally. Here we study a pair of tunnel-coupled one-dimensional atomic superfluids and characterize the corresponding quantum many-body problem by measuring correlation functions. We extract phase correlation functions up to tenth order from interference patterns and analyse whether, and under what conditions, these functions factorize into correlations of lower order. This analysis characterizes the essential features of our system, the relevant quasiparticles, their interactions and topologically distinct vacua. From our data we conclude that in thermal equilibrium our system can be seen as a quantum simulator of the sine-Gordon model, relevant for diverse disciplines ranging from particle physics to condensed matter. The measurement and evaluation of higher-order correlation functions can easily be generalized to other systems and to study correlations of any other observable such as density, spin and magnetization. It therefore represents a general method for analysing quantum many-body systems from experimental data.

Neutral O2 and Ion O2+ Sources from Rings into the Inner Magnetosphere

NASA Astrophysics Data System (ADS)

Elrod, M. K.; Johnson, R. E.; Cassidy, T. A.; Wilson, R. J.; Tseng, W.; Ip, W.

2009-12-01

The primary source of neutral O2 for Saturn’s magnetosphere is due to solar UV photons protons that produce O2 from H2O ice decomposition over the main rings as well as the tenuous F and G rings resulting in a tenuous O2 atmosphere (Johnson et. al. 2006). The O2 atmosphere is very thin to the point of being nearly collisionless. Our model of the atmosphere predict that as it interacts with the ring particles, the O2 is adsorbed and desorbed from the rings causing changes in the trajectories, which in turn, allows for a distribution of O2 from the rings throughout the magnetosphere (Tokar et. al. 2005; Tseng et. al. 2009). Predominately through photo-ionization and ion-exchange these O2 neutrals from the ice grains become a source for O2+ ions in the inner magnetosphere. Once the O2 becomes ionized to become O2+ the ions then follow the field lines. The ions interact with the ice particles in the rings to stick to the ring particles effectively reducing the ion density. As a result the ion density is greater over the Cassini Division and the area between the F and G ring where the optical depth due to the ice grain is less. Accordingly, the neutral O2 densities would tend to be high over the higher optical depth of the B and A main rings where the source rates are higher. Models of the neutral densities have shown high densities over the main rings, with a tail through the magnetosphere. Analysis of the CAPS (Cassini Plasma Spectrometer) data from the Saturn Orbit Insertion (SOI) in 2004 shows a peak in density over the Cassini Division and a higher peak in O2+ ion density between the F and G rings. References: Johnson, R.E., J.G. Luhmann, R.L. Tokar, M. Bouhram, J.J. Berthelier, E.C. Siler, J.F. Cooper, T.W. Hill, H.T. Smith, M. Michael, M. Liu, F.J. Crary, D.T. Young, "Production, Ionization and Redistribution of O2 Saturn's Ring Atmosphere" Icarus 180, 393-402 (2006).(pdf) Tokar, R.L., and 12 colleagues, 2005. Cassini Observations of the Thermal Plasma in the Vicinity of Saturn’s Main Rings and the F and G Rings. Geophys. Res. Lett. 32, doi:10.1029/2005GL022690. L14S04. Martens, H. R., Reisenfeld, D. B., Williams, J. D., Johnson, R.E., Smith H. T., “Observations of molecular oxygen ions in Saturn’s inner magnetosphere”. Geophy. Res. Lett. 2009. W.-L. Tseng, Ip, W.-H., Johnson, R. E., Cassidy, T. A., Elrod, M. K., “The Structure and Time Variability of the Ring atmosphere and ionosphere”. Geophy. Res. Lett. 2009.

ERBE S10 MFOV SF NAT

Atmospheric Science Data Center

2016-06-09

... detectors continuously view the earth disc (plus a small ring of space). The measurements are continuous over the entire globe for ... Page SCAR-B G8 FIRE Order Data: ASDC Order Tool:  Order Data ...

ERBE S10 WFOV NF NAT

Atmospheric Science Data Center

2016-06-09

... detectors continuously view the earth disc (plus a small ring of space). The measurements are continuous over the entire globe for ... Page SCAR-B G8 FIRE Order Data: ASDC Order Tool:  Order Data ...

ERBE S10 MFOV NF NAT

Atmospheric Science Data Center

2016-06-09

... detectors continuously view the earth disc (plus a small ring of space). The measurements are continuous over the entire globe for ... Page SCAR-B G8 FIRE Order Data: ASDC Order Tool:  Order Data ...

Piperazines as nootropic agents: New derivatives of the potent cognition-enhancer DM235 carrying hydrophilic substituents.

PubMed

Martino, Maria Vittoria; Guandalini, Luca; Di Cesare Mannelli, Lorenzo; Menicatti, Marta; Bartolucci, Gianluca; Dei, Silvia; Manetti, Dina; Teodori, Elisabetta; Ghelardini, Carla; Romanelli, Maria Novella

2017-03-15

The piperazine ring of the potent nootropic drug DM235 has been decorated with H-bond donor and acceptor groups (CH 2 OH, CH 2 OMe, CH 2 OCOMe, COOEt); the aim was to insert new functional groups, suitable for further chemical manipulation. The influence of these modifications on nootropic activity was assessed by means of the mouse passive avoidance test; some of the newly synthesized molecules (alcohol 7b, acetate 8b and ester 10d) showed interesting in vivo potency. This makes it possible to use these functional groups for adding other residues, in order to increase molecular diversity, or for anchoring a biotin group, to obtain compounds useful to capture the biological target. Moreover, the new compounds will improve our knowledge of structure activity relationships of this family of drugs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Natural product-like virtual libraries: recursive atom-based enumeration.

PubMed

Yu, Melvin J

2011-03-28

A new molecular enumerator is described that allows chemically and architecturally diverse sets of natural product-like and drug-like structures to be generated from a core structure as simple as a single carbon atom or as complex as a polycyclic ring system. Integrated with a rudimentary machine-learning algorithm, the enumerator has the ability to assemble biased virtual libraries enriched in compounds predicted to meet target criteria. The ability to dynamically generate relatively small focused libraries in a recursive manner could reduce the computational time and infrastructure necessary to construct and manage extremely large static libraries. Depending on enumeration conditions, natural product-like structures can be produced with a wide range of heterocyclic and alicyclic ring assemblies. Because natural products represent a proven source of validated structures for identifying and designing new drug candidates, mimicking the structural and topological diversity found in nature with a dynamic set of virtual natural product-like compounds may facilitate the creation of new ideas for novel, biologically relevant lead structures in areas of uncharted chemical space.

A Compact Trench-Assisted Multi-Orbital-Angular-Momentum Multi-Ring Fiber for Ultrahigh-Density Space-Division Multiplexing (19 Rings × 22 Modes)

PubMed Central

Li, Shuhui; Wang, Jian

2014-01-01

We present a compact (130 μm cladding diameter) trench-assisted multi-orbital-angular-momentum (OAM) multi-ring fiber with 19 rings each supporting 22 modes with 18 OAM ones. Using the high-contrast-index ring and trench designs, the trench-assisted multi-OAM multi-ring fiber (TA-MOMRF) features both low-level inter-mode crosstalk and inter-ring crosstalk within a wide wavelength range (1520 to 1630 nm), which can potentially enable Pbit/s total transmission capacity and hundreds bit/s/Hz spectral efficiency in a single TA-MOMRF. Moreover, the effective refractive index difference of even and odd fiber eigenmodes induced by the ellipticity of ring and fiber bending and their impacts on the purity of OAM mode and mode coupling/crosstalk are analyzed. It is found that high-order OAM modes show preferable tolerance to the ring ellipticity and fiber bending. The designed fiber offers favorable tolerance to both small ellipticity of ring (<−22 dB crosstalk under an ellipticity of 0.5%) and small bend radius (<−20 dB crosstalk under a bend radius of 2 cm). PMID:24458159

Climate-growth relationships of Abies spectabilis in a central Himalayan treeline ecotone

NASA Astrophysics Data System (ADS)

Schwab, Niels; Kaczka, Ryszard J.; Schickhoff, Udo

2017-04-01

Climate warming is expected to induce treelines to advance to higher elevations. Empirical studies in diverse mountain ranges, however, give evidence of both advancing alpine treelines as well as rather insignificant responses. The large spectrum of responses is not fully understood. In the framework of investigating the sensitivity and response of a near-natural treeline ecotone in Rolwaling Himal, Nepal, to climate warming we present results from dendroclimatological analyses of Abies spectabilis (Himalayan Fir) increment cores. Tree ring width was measured and cross-dated. After standardization, the chronology was correlated with temperature and precipitation variables. Preliminary results point to positive correlations with autumn temperature and precipitation. We will present improved climate-growth relationships. The resulting climate - tree growth relationships may be used as an indication of future growth patterns and treeline dynamics under climate change conditions.

Reflective optical imaging system with balanced distortion

DOEpatents

Chapman, Henry N.; Hudyma, Russell M.; Shafer, David R.; Sweeney, Donald W.

1999-01-01

An optical system compatible with short wavelength (extreme ultraviolet) An optical system compatible with short wavelength (extreme ultraviolet) radiation comprising four reflective elements for projecting a mask image onto a substrate. The four optical elements comprise, in order from object to image, convex, concave, convex and concave mirrors. The optical system is particularly suited for step and scan lithography methods. The invention enables the use of larger slit dimensions associated with ring field scanning optics, improves wafer throughput and allows higher semiconductor device density. The inventive optical system is characterized by reduced dynamic distortion because the static distortion is balanced across the slit width.

Non-isothermal elastoviscoplastic analysis of planar curved beams

NASA Technical Reports Server (NTRS)

Simitses, G. J.; Carlson, R. L.; Riff, R.

1988-01-01

The development of a general mathematical model and solution methodologies, to examine the behavior of thin structural elements such as beams, rings, and arches, subjected to large nonisothermal elastoviscoplastic deformations is presented. Thus, geometric as well as material type nonlinearities of higher order are present in the analysis. For this purpose a complete true abinito rate theory of kinematics and kinetics for thin bodies, without any restriction on the magnitude of the transformation is presented. A previously formulated elasto-thermo-viscoplastic material constitutive law is employed in the analysis. The methodology is demonstrated through three different straight and curved beams problems.

Fourier analysis algorithm for the posterior corneal keratometric data: clinical usefulness in keratoconus.

PubMed

Sideroudi, Haris; Labiris, Georgios; Georgantzoglou, Kimon; Ntonti, Panagiota; Siganos, Charalambos; Kozobolis, Vassilios

2017-07-01

To develop an algorithm for the Fourier analysis of posterior corneal videokeratographic data and to evaluate the derived parameters in the diagnosis of Subclinical Keratoconus (SKC) and Keratoconus (KC). This was a cross-sectional, observational study that took place in the Eye Institute of Thrace, Democritus University, Greece. Eighty eyes formed the KC group, 55 eyes formed the SKC group while 50 normal eyes populated the control group. A self-developed algorithm in visual basic for Microsoft Excel performed a Fourier series harmonic analysis for the posterior corneal sagittal curvature data. The algorithm decomposed the obtained curvatures into a spherical component, regular astigmatism, asymmetry and higher order irregularities for averaged central 4 mm and for each individual ring separately (1, 2, 3 and 4 mm). The obtained values were evaluated for their diagnostic capacity using receiver operating curves (ROC). Logistic regression was attempted for the identification of a combined diagnostic model. Significant differences were detected in regular astigmatism, asymmetry and higher order irregularities among groups. For the SKC group, the parameters with high diagnostic ability (AUC > 90%) were the higher order irregularities, the asymmetry and the regular astigmatism, mainly in the corneal periphery. Higher predictive accuracy was identified using diagnostic models that combined the asymmetry, regular astigmatism and higher order irregularities in averaged 3and 4 mm area (AUC: 98.4%, Sensitivity: 91.7% and Specificity:100%). Fourier decomposition of posterior Keratometric data provides parameters with high accuracy in differentiating SKC from normal corneas and should be included in the prompt diagnosis of KC. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

Chlorinated hydrocarbon contaminants in arctic marine mammals.

PubMed

Norstrom, R J; Muir, D C

1994-09-16

By 1976, the presence of chlorinated hydrocarbon contaminants (CHCs) had been demonstrated in fur seal (Callorhinus ursinus), ringed seal (Phoca hispida), hooded seal (Cystophora cristata), bearded seal (Erignathus barbatus), walrus (Obdobenus rosmarus divergens), beluga (Delphinapterus leucas), porpoise (Phocoena phocoena) and polar bear (Ursus maritimus) in various parts of the Arctic. In spite of this early interest, very little subsequent research on contaminants in Arctic marine mammals was undertaken until the mid-1980s. Since that time, there has been an explosion of interest, resulting in a much expanded data base on contaminants in Arctic marine mammals. Except in the Russian Arctic, data have now been obtained on the temporospatial distribution of PCBs and other contaminants in ringed seal, beluga and polar bear. Contaminants in narwhal (Monodon monoceros) have also now been measured. On a fat weight basis, the sum of DDT-related compounds (S-DDT) and PCB levels are lowest in walrus (< 0.1 microgram/g), followed by ringed seal, (0.1-1 microgram/g range). Levels are an order of magnitude higher in beluga and narwhal (1-10 micrograms/g range). It appears that metabolism and excretion of S-DDT and PCBs may be less efficient in cetaceans, leading to greater biomagnification. Polar bears have similar levels of PCBs as cetaceans (1-10 micrograms/g), but with a much simpler congener pattern. DDE levels are lowest in polar bear, indicating rapid metabolism. Effects of age and sex on residue levels are found for all species where this was measured. Among cetaceans and ringed seal, sexually mature females have lower levels than males due to lactation. Although PCB levels in adult male polar bears are about twice as high as females, there is only a trivial age effect in either sex apart from an initial decrease from birth to sexual maturity (age 0-5). Comparison of levels of S-DDT and PCBs in Arctic beluga and ringed seal with those in beluga in the Gulf of St. Lawrence and ringed seal in the Baltic Sea, indicate that overall contamination of the Arctic marine ecosystem is 10-50 times less than the most highly contaminated areas in the northern hemisphere temperate latitude marine environment. Geographic distribution of residue levels in polar bears indicates a gradual increase from Alaska east to Svalbard, except PCB levels are significantly higher in eastern Greenland and Svalbard. Information on temporal trends is somewhat contradictory.(ABSTRACT TRUNCATED AT 400 WORDS)

Reading, Writing, and Rings!

ERIC Educational Resources Information Center

Aschbacher, Pamela; Li, Erika; Hammon, Art

2008-01-01

"Reading, Writing, and Rings!" was created by a team of elementary teachers, literacy experts, and scientists in order to integrate science and literacy. These free units bring students inside NASA's Cassini-Huygens mission to Saturn. The authors--a science teacher and education outreach specialist and two evaluators of educational programs--have…

An alternative way to increase the power gain of resonant rings

NASA Astrophysics Data System (ADS)

Zhuang, Dehao; Liu, Yunqi; Wang, Fang; Lin, Lin; Feng, Liwen; Quan, Shengwen; Liu, Kexin

2018-03-01

Resonant rings which can amplify RF power through the coupling of waves are used for high power breakdown tests, unidirectional filters, or pulse-shaping techniques. Usually, the RF output terminal of a resonant ring is connected to a matched load. For the resonant ring at Peking University, the matched load has been replaced by a waveguide shorting plate to obtain higher conditioning power for the 1.3 GHz capacitive type power couplers. The power gain is increased significantly with this short termination with the same input RF power. Working mechanism analysis, experiments, and results of this modified resonant ring will be presented.

The Anatomical Relationship Between Recurrent Laryngeal Nerve and First Tracheal Ring in Males and Females.

PubMed

Akil, Ferit; Yollu, Umur; Ayral, Muhammed; Turgut, Faith; Yener, Murat

2017-03-01

Despite the modern advances in thyroid surgery, recurrent laryngeal nerve (rln) paralysis is still a critical problem. In order to decrease the rate of this complication, rln anatomy has been studied intensively. In our study, we aimed to recognize the relationship of rln and landmarks of the first tracheal ring. Eighty-six female and 18 male patients who were undergone total thyroidectomy were included in this study. Trachea vertical height (tvh), right recurrent laryngeal nerve height (rrh), left recurrent laryngeal nerve height (lrh), right recurrent laryngeal nerve to trachea anterior face median raphe distance (rrd), left recurrent laryngeal nerve to trachea anterior face median raphe distance (lrd), right recurrent laryngeal nerve respect to trachea ratio (rrtr), and left recurrent laryngeal nerve respect to trachea ratio (lrtr) parameters of all patients were measured and compared in males and females using independent t -test and measurements on both right and left sides were compared statistically without sex discrimination. There were no significant differences between groups in tvh, rrh, rrd, lrd, rrtr, and lrtr parameters. Lrh parameter was significantly higher in males than in females ( P <0.04). Comparison of right and left sides revealed that lrh was significantly higher than rrh ( P <0.001), lrd was significantly higher than rrd ( P <0.001), and rrtr was significantly higher than lrtr ( P <0.001). In this study, we have shown that in all cases the rln was located around the lower half of trachea vertical length and at this level left rln was located significantly deeper than the right side.

The Anatomical Relationship Between Recurrent Laryngeal Nerve and First Tracheal Ring in Males and Females

PubMed Central

Akil, Ferit; Yollu, Umur; Ayral, Muhammed; Turgut, Faith; Yener, Murat

2017-01-01

Objectives Despite the modern advances in thyroid surgery, recurrent laryngeal nerve (rln) paralysis is still a critical problem. In order to decrease the rate of this complication, rln anatomy has been studied intensively. In our study, we aimed to recognize the relationship of rln and landmarks of the first tracheal ring. Methods Eighty-six female and 18 male patients who were undergone total thyroidectomy were included in this study. Trachea vertical height (tvh), right recurrent laryngeal nerve height (rrh), left recurrent laryngeal nerve height (lrh), right recurrent laryngeal nerve to trachea anterior face median raphe distance (rrd), left recurrent laryngeal nerve to trachea anterior face median raphe distance (lrd), right recurrent laryngeal nerve respect to trachea ratio (rrtr), and left recurrent laryngeal nerve respect to trachea ratio (lrtr) parameters of all patients were measured and compared in males and females using independent t-test and measurements on both right and left sides were compared statistically without sex discrimination. Results There were no significant differences between groups in tvh, rrh, rrd, lrd, rrtr, and lrtr parameters. Lrh parameter was significantly higher in males than in females (P<0.04). Comparison of right and left sides revealed that lrh was significantly higher than rrh (P<0.001), lrd was significantly higher than rrd (P<0.001), and rrtr was significantly higher than lrtr (P<0.001). Conclusion In this study, we have shown that in all cases the rln was located around the lower half of trachea vertical length and at this level left rln was located significantly deeper than the right side. PMID:27337947

Computer program documentation for the dynamic analysis of a noncontacting mechanical face seal

NASA Technical Reports Server (NTRS)

Auer, B. M.; Etsion, I.

1980-01-01

A computer program is presented which achieves a numerical solution for the equations of motion of a noncontacting mechanical face seal. The flexibly-mounted primary seal ring motion is expressed by a set of second order differential equations for three degrees of freedom. These equations are reduced to a set of first order equations and the GEAR software package is used to solve the set of first order equations. Program input includes seal design parameters and seal operating conditions. Output from the program includes velocities and displacements of the seal ring about the axis of an inertial reference system. One example problem is described.

Union Type and Depressive Symptoms among Mexican Adults

ERIC Educational Resources Information Center

Schmeer, Kammi K.; Kroeger, Rhiannon A.

2011-01-01

Diversity in union type is increasing around the world as cohabitation and higher order unions become more prevalent in developing and developed countries. This necessitates a more nuanced understanding of how different union types relate to individual well-being across social settings. In this study, the authors analyze nationally-representative…

Mechanical improvement of metal reinforcement rings for a finite ring-shaped superconducting bulk

NASA Astrophysics Data System (ADS)

Huang, Chen-Guang; Zhou, You-He

2018-03-01

As a key technique, reinforcement of type-II superconducting bulks with metal rings can efficiently improve their mechanical properties to enhance the maximum trapped field. In this paper, we study the magnetostrictive and fracture behaviors of a finite superconducting ring bulk reinforced by three typical reinforcing structures composed of metal rings during the magnetizing process by means of the minimization of magnetic energy and the finite element method. After a field-dependent critical current density is adopted, the magnetostriction, pinning-induced stress, and crack tip stress intensity factor are calculated considering the demagnetization effects. The results show that the mechanical properties of the ring bulk are strongly dependent on the reinforcing structure and the material and geometrical parameters of the metal rings. Introducing the metal ring can significantly reduce the hoop stress, and the reduction effect by internal reinforcement is much improved relative to external reinforcement. By comparison, bilateral reinforcement seems to be the best candidate structure. Only when the metal rings have particular Young's modulus and radial thickness will they contribute to improve the mechanical properties the most. In addition, if an edge crack is pre-existing in the ring bulk, the presence of metal rings can effectively avoid crack propagation since it reduces the crack tip stress intensity factor by nearly one order of magnitude.

Present and future of scientific bird ringing

USGS Publications Warehouse

Spina, F.; Tautin, J.; Adams, N.J.; Slotow, R.H.

1998-01-01

In 1999 scientific bird ringing will celebrate its first century of existence. Started mainly to investigate bird movements, bird ringing has become a much more flexible method to study different aspects of bird biology. Bird ringing can only be properly organised if an effective international co-operation exists. In Europe, this co-ordination is ensured by EURING, made of 35 national ringing centres; sister organisations exist in other parts of the world (like Africa, Australia, U.S. and Canada), sharing the same aims and problems. This RTD is mainly targeted to ornithologists involved with the co-ordination of bird ringing stations and national centres world-wide. Common aspects of the organisation of ringing activities, as well as of the potential ringing has and will have in the future in addressing major scientific questions in Ornithology will be taken into account. The advisability of setting up a standing committee on bird ringing within the IOC will be discussed, and the project of creating a world-wide organisation of ringing schemes in order to further improve communication and exchange of experiences will also be addressed. This new organisation would be formally founded in 1999, when an international conference organised by EURING to celebrate the first 100 years of bird ringing will be held in Denmark.

Present and future of scientific bird ringing

USGS Publications Warehouse

Spina, F.; Tautin, J.; Adams, N.J.; Slotow, R.H.

1999-01-01

In 1999 scientific bird ringing will celebrate its first century of existence. Started mainly to investigate bird movements, bird ringing has become a much more flexible method to study different aspects of bird biology. Bird ringing can only be properly organised if an effective international co-operation exists. In Europe, this co-ordination is ensured by EURING, made of 35 national ringing centres; sister organisations exist in other parts of the world (like Africa, Australia, U.S. and Canada), sharing the same aims and problems. This RTD is mainly targeted to ornithologists involved with the co-ordination of bird ringing stations and national centres world-wide. Common aspects of the organisation of ringing activities, as well as of the potential ringing has and will have in the future in addressing major scientific questions in Ornithology will be taken into account. The advisability of setting up a standing committee on bird ringing within the IOC will be discussed, and the project of creating a world-wide organisation of ringing schemes in order to further improve communication and exchange of experiences will also be addressed. This new organisation would be formally founded in 1999, when an international conference organised by EURING to celebrate the first 100 years of bird ringing will be held in Denmark.

Time-resolved spectral characterization of ring cavity surface emitting and ridge-type distributed feedback quantum cascade lasers by step-scan FT-IR spectroscopy.

PubMed

Brandstetter, Markus; Genner, Andreas; Schwarzer, Clemens; Mujagic, Elvis; Strasser, Gottfried; Lendl, Bernhard

2014-02-10

We present the time-resolved comparison of pulsed 2nd order ring cavity surface emitting (RCSE) quantum cascade lasers (QCLs) and pulsed 1st order ridge-type distributed feedback (DFB) QCLs using a step-scan Fourier transform infrared (FT-IR) spectrometer. Laser devices were part of QCL arrays and fabricated from the same laser material. Required grating periods were adjusted to account for the grating order. The step-scan technique provided a spectral resolution of 0.1 cm(-1) and a time resolution of 2 ns. As a result, it was possible to gain information about the tuning behavior and potential mode-hops of the investigated lasers. Different cavity-lengths were compared, including 0.9 mm and 3.2 mm long ridge-type and 0.97 mm (circumference) ring-type cavities. RCSE QCLs were found to have improved emission properties in terms of line-stability, tuning rate and maximum emission time compared to ridge-type lasers.

ERBE S10N WFV SF NAT

Atmospheric Science Data Center

2016-06-14

... detectors continuously view the earth disc (plus a small ring of space). The measurements are continuous over the entire globe for ... Page SCAR-B G8 FIRE Order Data: ASDC Order Tool:  Order Data ...

ERBE S10N WFV NF NAT

Atmospheric Science Data Center

2016-06-13

... detectors continuously view the earth disc (plus a small ring of space). The measurements are continuous over the entire globe for ... Page SCAR-B G8 FIRE Order Data: ASDC Order Tool:  Order Data ...

Study of a Tricarbide Grooved Ring Fuel Element for Nuclear Thermal Propulsion

NASA Technical Reports Server (NTRS)

Taylor, Brian; Emrich, Bill; Tucker, Dennis; Barnes, Marvin; Donders, Nicolas; Benensky, Kelsa

2018-01-01

Deep space exploration, especially that of Mars, is on the horizon as the next big challenge for space exploration. Nuclear propulsion, through which high thrust and efficiency can be achieved, is a promising option for decreasing the cost and logistics of such a mission. Work on nuclear thermal engines goes back to the days of the NERVA program. Currently, nuclear thermal propulsion is under development again in various forms to provide a superior propulsion system for deep space exploration. The authors have been working to develop a concept nuclear thermal engine that uses a grooved ring fuel element as an alternative to the traditional hexagonal rod design. The authors are also studying the use of carbide fuels. The concept was developed in order to increase surface area and heat transfer to the propellant. The use of carbides would also raise the operating temperature of the reactor. It is hoped that this could lead to a higher thrust to weight nuclear thermal engine. This paper describes the modeling of neutronics, heat transfer, and fluid dynamics of this alternative nuclear fuel element geometry. Fabrication experiments of grooved rings from carbide refractory metals are also presented along with material characterization and interactions with a hot hydrogen environment. Results of experiments and associated analysis are discussed. The authors demonstrated success in reaching desired densities with some success in material distribution and reaching a solid solution. Future work is needed to improve distribution of material, minimize oxidation during the milling process, and define a fabrication process that will serve for constructing grooved ring fuel rods for large system tests.

Study of a Tricarbide Grooved Ring Fuel Element for Nuclear Thermal Propulsion

NASA Technical Reports Server (NTRS)

Taylor, Brian; Emrich, Bill; Tucker, Dennis; Barnes, Marvin; Donders, Nicolas; Benensky, Kelsa

2018-01-01

Deep space exploration, especially that of Mars, is on the horizon as the next big challenge for space exploration. Nuclear propulsion, through which high thrust and efficiency can be achieved, is a promising option for decreasing the cost and logistics of such a mission. Work on nu- clear thermal engines goes back to the days of the NERVA program. Currently, nuclear thermal propulsion is under development again in various forms to provide a superior propulsion system for deep space exploration. The authors have been working to develop a concept nuclear thermal engine that uses a grooved ring fuel element as an alternative to the traditional hexagonal rod design. The authors are also studying the use of carbide fuels. The concept was developed in order to increase surface area and heat transfer to the propellant. The use of carbides would also raise the operating temperature of the reactor. It is hoped that this could lead to a higher thrust to weight nuclear thermal engine. This paper describes the modeling of neutronics, heat transfer, and fluid dynamics of this alternative nuclear fuel element geometry. Fabrication experiments of grooved rings from carbide refractory metals are also presented along with material characterization and interactions with a hot hydrogen environment. Results of experiments and associated analysis are desired densities with some success in material distribution and reaching a solid solution. Future work is needed to improve distribution of material, minimize oxidation during the milling process, and de ne a fabrication process that will serve for constructing grooved ring fuel rods for large system tests.

EVOLUTION OF NEAR-SURFACE FLOWS INFERRED FROM HIGH-RESOLUTION RING-DIAGRAM ANALYSIS

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

Bogart, Richard S.; Baldner, Charles S.; Basu, Sarbani

2015-07-10

Ring-diagram analysis of acoustic waves observed at the photosphere can provide a relatively robust determination of the sub-surface flows at a particular time under a particular region. The depth of penetration of the waves is related to the size of the region, hence the depth extent of the measured flows is inversely proportional to the spatial resolution. Most ring-diagram analysis has focused on regions of extent ∼15° (180 Mm) or more in order to provide reasonable mode sets for inversions. Helioseismic and Magnetic Imager (HMI) data analysis also provides a set of ring fit parameters on a scale three timesmore » smaller. These provide flow estimates for the outer 1% (7 Mm) of the Sun only, with very limited depth resolution, but with spatial resolution adequate to map structures potentially associated with the belts and regions of magnetic activity. There are a number of systematic effects affecting the determination of flows from a local helioseismic analysis of regions over different parts of the observable disk, and not all of them are well understood. In this study we characterize those systematic effects with higher spatial resolution so that they may be accounted for more effectively in mapping the temporal and spatial evolution of the flows. Leaving open the question of the mean structure of the global meridional circulation and the differential rotation, we describe the near-surface flow anomalies in time and latitude corresponding to the torsional oscillation pattern in differential rotation and analogous patterns in the meridional cell structure as observed by the Solar Dynamics Observatory/HMI.« less

A new systematic calibration method of ring laser gyroscope inertial navigation system

NASA Astrophysics Data System (ADS)

Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Xiong, Zhenyu; Long, Xingwu

2016-10-01

Inertial navigation system has been the core component of both military and civil navigation systems. Before the INS is put into application, it is supposed to be calibrated in the laboratory in order to compensate repeatability error caused by manufacturing. Discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed theories of error inspiration and separation in detail and presented a new systematic calibration method for ring laser gyroscope inertial navigation system. Error models and equations of calibrated Inertial Measurement Unit are given. Then proper rotation arrangement orders are depicted in order to establish the linear relationships between the change of velocity errors and calibrated parameter errors. Experiments have been set up to compare the systematic errors calculated by filtering calibration result with those obtained by discrete calibration result. The largest position error and velocity error of filtering calibration result are only 0.18 miles and 0.26m/s compared with 2 miles and 1.46m/s of discrete calibration result. These results have validated the new systematic calibration method and proved its importance for optimal design and accuracy improvement of calibration of mechanically dithered ring laser gyroscope inertial navigation system.

A structural analysis of the AAA+ domains in Saccharomyces cerevisiae cytoplasmic dynein.

PubMed

Gleave, Emma S; Schmidt, Helgo; Carter, Andrew P

2014-06-01

Dyneins are large protein complexes that act as microtubule based molecular motors. The dynein heavy chain contains a motor domain which is a member of the AAA+ protein family (ATPases Associated with diverse cellular Activities). Proteins of the AAA+ family show a diverse range of functionalities, but share a related core AAA+ domain, which often assembles into hexameric rings. Dynein is unusual because it has all six AAA+ domains linked together, in one long polypeptide. The dynein motor domain generates movement by coupling ATP driven conformational changes in the AAA+ ring to the swing of a motile element called the linker. Dynein binds to its microtubule track via a long antiparallel coiled-coil stalk that emanates from the AAA+ ring. Recently the first high resolution structures of the dynein motor domain were published. Here we provide a detailed structural analysis of the six AAA+ domains using our Saccharomycescerevisiae crystal structure. We describe how structural similarities in the dynein AAA+ domains suggest they share a common evolutionary origin. We analyse how the different AAA+ domains have diverged from each other. We discuss how this is related to the function of dynein as a motor protein and how the AAA+ domains of dynein compare to those of other AAA+ proteins. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Deviation of the typical AAA substrate-threading pore prevents fatal protein degradation in yeast Cdc48.

PubMed

Esaki, Masatoshi; Islam, Md Tanvir; Tani, Naoki; Ogura, Teru

2017-07-14

Yeast Cdc48 is a well-conserved, essential chaperone of ATPases associated with diverse cellular activity (AAA) proteins, which recognizes substrate proteins and modulates their conformations to carry out many cellular processes. However, the fundamental mechanisms underlying the diverse pivotal roles of Cdc48 remain unknown. Almost all AAA proteins form a ring-shaped structure with a conserved aromatic amino acid residue that is essential for proper function. The threading mechanism hypothesis suggests that this residue guides the intrusion of substrate proteins into a narrow pore of the AAA ring, thereby becoming unfolded. By contrast, the aromatic residue in one of the two AAA rings of Cdc48 has been eliminated through evolution. Here, we show that artificial retrieval of this aromatic residue in Cdc48 is lethal, and essential features to support the threading mechanism are required to exhibit the lethal phenotype. In particular, genetic and biochemical analyses of the Cdc48 lethal mutant strongly suggested that when in complex with the 20S proteasome, essential proteins are abnormally forced to thread through the Cdc48 pore to become degraded, which was not detected in wild-type Cdc48. Thus, the widely applicable threading model is less effective for wild-type Cdc48; rather, Cdc48 might function predominantly through an as-yet-undetermined mechanism.

Early universe cosmology, effective supergravity, and invariants of algebraic forms

NASA Astrophysics Data System (ADS)

Sinha, Kuver

2015-09-01

The presence of light scalars can have profound effects on early universe cosmology, influencing its thermal history as well as paradigms like inflation and baryogenesis. Effective supergravity provides a framework to make quantifiable, model-independent studies of these effects. The Riemannian curvature of the Kähler manifold spanned by scalars belonging to chiral superfields, evaluated along supersymmetry breaking directions, provides an order parameter (in the sense that it must necessarily take certain values) for phenomena as diverse as slow roll modular inflation, nonthermal cosmological histories, and the viability of Affleck-Dine baryogenesis. Within certain classes of UV completions, the order parameter for theories with n scalar moduli is conjectured to be related to invariants of n -ary cubic forms (for example, for models with three moduli, the order parameter is given by a function on the ring of invariants spanned by the Aronhold invariants). Within these completions, and under the caveats spelled out, this may provide an avenue to obtain necessary conditions for the above phenomena that are in principle calculable given nothing but the intersection numbers of a Calabi-Yau compactification geometry. As an additional result, abstract relations between holomorphic sectional and bisectional curvatures are utilized to constrain Affleck-Dine baryogenesis on a wide class of Kähler geometries.

Characterization of heterocyclic rings through quantum chemical topology.

PubMed

Griffiths, Mark Z; Popelier, Paul L A

2013-07-22

Five-membered rings are found in a myriad of molecules important in a wide range of areas such as catalysis, nutrition, and drug and agrochemical design. Systematic insight into their largely unexplored chemical space benefits from first principle calculations presented here. This study comprehensively investigates a grand total of 764 different rings, all geometry optimized at the B3LYP/6-311+G(2d,p) level, from the perspective of Quantum Chemical Topology (QCT). For the first time, a 3D space of local topological properties was introduced, in order to characterize rings compactly. This space is called RCP space, after the so-called ring critical point. This space is analogous to BCP space, named after the bond critical point, which compactly and successfully characterizes a chemical bond. The relative positions of the rings in RCP space are determined by the nature of the ring scaffold, such as the heteroatoms within the ring or the number of π-bonds. The summed atomic QCT charges of the five ring atoms revealed five features (number and type of heteroatom, number of π-bonds, substituent and substitution site) that dictate a ring's net charge. Each feature independently contributes toward a ring's net charge. Each substituent has its own distinct and systematic effect on the ring's net charge, irrespective of the ring scaffold. Therefore, this work proves the possibility of designing a ring with specific properties by fine-tuning it through manipulation of these five features.

Radiolysis of paracetamol in dilute aqueous solution

NASA Astrophysics Data System (ADS)

Szabó, László; Tóth, Tünde; Homlok, Renáta; Takács, Erzsébet; Wojnárovits, László

2012-09-01

Using radiolytic experiments hydroxyl radical (main reactant in advanced oxidation processes) was shown to effectively destroy paracetamol molecules. The basic reaction is attachment to the ring. The hydroxy-cyclohexadienyl radical produced in the further reactions may transform to hydroxylated paracetamol derivatives or to quinone type molecules and acetamide. The initial efficiency of aromatic ring destruction in the absence of dissolved O2 is c.a. 10%. The efficiency is 2-3 times higher in the presence of O2 due to its reaction with intermediate hydroxy-cyclohexadienyl radical and the subsequent ring destruction reactions through peroxi radical. Upon irradiation the toxicity of solutions at low doses increases with the dose and then at higher doses it decreases. This is due to formation of compounds with higher toxicity than paracetamol (e.g. acetamide, hidroquinone). These products, however, are highly sensitive to irradiation and degrade easily.

Biomechanical and morphological differences between the sclera canal ring and a peripheral sclera ring in the porcine eye.

PubMed

Terai, Naim; Schlötzer-Schrehardt, Ursula; Spoerl, Eberhard; Hornykewycz, Karin; Haentzschel, Janek; Haustein, Michael; Pillunat, Lutz E

2012-01-01

To investigate a possible association between the biomechanical load and unload behaviour and the elastin content of the sclera canal ring (SCR) and a superiorly localized sclera ring (SPS) in the porcine eye. Two sclera rings were trephined from each of 40 porcine eyes, one containing the SCR and the other an SPS. The load and the unload curves were measured in the extension range of 0-2.0 mm by a biomaterial tester. Hysteresis was determined from the area enclosed by the loading and unloading curve. Histochemical staining with resorcin-fuchsin and morphometric analysis of paraffin-embedded sections of both rings were performed to detect the area occupied by elastin fibres. At 1 mm extension, the mean load of the SCR was 0.89 ± 0.22 N and that of the SPS 1.13 ± 0.19 N, which was not significantly different between both rings (p > 0.05). Mean hysteresis in the SCR was 1.55 ± 0.30 N × mm and 1.90 ± 0.18 N × mm in the SPS, which was significantly different between both rings (p = 0.01). Mean sclera thickness was 986 μm in the SCR (range: 900-1,060 μm) and 971 μm in the SPS (range: 800-1,200 μm) without a statistically significant difference between both sclera rings (p = 0.78). The area occupied by elastin fibres was 15.5 ± 3.4% in the SCR and 4.5 ± 1.5% in the SPS, which was significantly different between both rings (p = 0.0001). Hysteresis in the SCR was significantly lower than in the SPS, indicating a higher elasticity of the SCR in the porcine eye. This effect could be explained by a higher content of elastin in the surrounding ring of the peripapillary optic nerve head providing reversible contraction in cases of intra-ocular pressure variations. Copyright © 2011 S. Karger AG, Basel.

Spatial-mode switchable ring fiber laser based on low mode-crosstalk all-fiber mode MUX/DEMUX

NASA Astrophysics Data System (ADS)

Ren, Fang; Yu, Jinyi; Wang, Jianping

2018-05-01

We report an all-fiber ring laser that emits linearly polarized (LP) modes based on the intracavity all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). Multiple LP modes in ring fiber laser are generated by taking advantage of mode MUX/DEMUX. The all-fiber mode MUX/DEMUX are composed of cascaded mode-selective couplers (MSCs). The output lasing mode of the ring fiber laser can be switched among the three lowest-order LP modes by employing combination of a mode MUX and a simple N × 1 optical switch. The slope efficiencies, optical spectra and mode profiles are measured.

Maintaining mimicry diversity: optimal warning colour patterns differ among microhabitats in Amazonian clearwing butterflies.

PubMed

Willmott, Keith R; Robinson Willmott, Julia C; Elias, Marianne; Jiggins, Chris D

2017-05-31

Mimicry is one of the best-studied examples of adaptation, and recent studies have provided new insights into the role of mimicry in speciation and diversification. Classical Müllerian mimicry theory predicts convergence in warning signal among protected species, yet tropical butterflies are exuberantly diverse in warning colour patterns, even within communities. We tested the hypothesis that microhabitat partitioning in aposematic butterflies and insectivorous birds can lead to selection for different colour patterns in different microhabitats and thus help maintain mimicry diversity. We measured distribution across flight height and topography for 64 species of clearwing butterflies (Ithomiini) and their co-mimics, and 127 species of insectivorous birds, in an Amazon rainforest community. For the majority of bird species, estimated encounter rates were non-random for the two most abundant mimicry rings. Furthermore, most butterfly species in these two mimicry rings displayed the warning colour pattern predicted to be optimal for anti-predator defence in their preferred microhabitats. These conclusions were supported by a field trial using butterfly specimens, which showed significantly different predation rates on colour patterns in two microhabitats. We therefore provide the first direct evidence to support the hypothesis that different mimicry patterns can represent stable, community-level adaptations to differing biotic environments. © 2017 The Author(s).

Maintaining mimicry diversity: optimal warning colour patterns differ among microhabitats in Amazonian clearwing butterflies

PubMed Central

Robinson Willmott, Julia C.

2017-01-01

Mimicry is one of the best-studied examples of adaptation, and recent studies have provided new insights into the role of mimicry in speciation and diversification. Classical Müllerian mimicry theory predicts convergence in warning signal among protected species, yet tropical butterflies are exuberantly diverse in warning colour patterns, even within communities. We tested the hypothesis that microhabitat partitioning in aposematic butterflies and insectivorous birds can lead to selection for different colour patterns in different microhabitats and thus help maintain mimicry diversity. We measured distribution across flight height and topography for 64 species of clearwing butterflies (Ithomiini) and their co-mimics, and 127 species of insectivorous birds, in an Amazon rainforest community. For the majority of bird species, estimated encounter rates were non-random for the two most abundant mimicry rings. Furthermore, most butterfly species in these two mimicry rings displayed the warning colour pattern predicted to be optimal for anti-predator defence in their preferred microhabitats. These conclusions were supported by a field trial using butterfly specimens, which showed significantly different predation rates on colour patterns in two microhabitats. We therefore provide the first direct evidence to support the hypothesis that different mimicry patterns can represent stable, community-level adaptations to differing biotic environments. PMID:28539522

BrRZFP1 a Brassica rapa C3HC4-type RING zinc finger protein involved in cold, salt and dehydration stress.

PubMed

Jung, Y J; Lee, I H; Nou, I S; Lee, K D; Rashotte, A M; Kang, K K

2013-03-01

C3HC4-type RING zinc finger proteins are known to be essential in the regulation of plant processes, including responses to abiotic stress. Here, we identify, clone and examine the first C3HC4-type RING zinc finger protein (BrRZFP1) from Brassica rapa under stress conditions. Phylogenetic analysis of BrRZFP1 revealed strong sequence similarity to C3HC4-type zinc finger proteins from Arabidopsis that are induced by abiotic stresses. Diverse environmental stresses, including salt and cold, were found to induce BrRZFP1 transcripts greater than eightfold in B. rapa. Additional strong induction was shown of the stress hormone abscisic acid, together suggesting that BrRZFP1 could play a role as a general stress modulator. Similar profiles of induction for each of these stresses was found in both root and shoot tissues, although at much higher levels in roots. Constitutive expression of BrRZFP1 in Nicotiana tabacum was conducted to further analyse how changes in gene expression levels would affect plant stress responses. BrRZFP1 overexpression conferred increased tolerance to cold, salt and dehydration stresses. This was observed in several assays examining growth status throughout development, including increased germination, fresh weight and length of shoots and roots, as well as enhanced chlorophyll retention. These results suggest that the transcription factor BrRZFP1 is an important determinant of stress response in plants and that changes in its expression level in plants could increase stress tolerance. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Hydrolysis of Dihydrouridine and Related Compounds

NASA Technical Reports Server (NTRS)

House, Christopher H.; Miller, Stanley L.

1996-01-01

Dihydrouridine is absent from the tRNA of almost all hyperthermophiles and most Archaea but is ubiquitous in the tRNA of Eubacteria and Eukaryotes. In order to investigate whether this could be due to instability, the rate of ring opening of dihydrouridine was measured between 25 and 120 C. The dihydrouridine ring is stable at 25 C, but the half-life at 100 C and pH 7 is 9.1 h, which is comparable to the doubling time of hyperthermophiles. This suggests an explanation for the absence of dihydrouridine from the tRNA of hyperthermophiles. The rates of ring opening of dihydrouracil, dihydrothymine, and 1-N-methyldihydrouracil were measured at 100 C and pH 6-9, as were the equilibrium constants for ring closure of the ureido acids to the dihydrouracils. The pH rate profiles for ring opening and ring closing were calculated from the data. Possible roles for dihydrouracils in the pre-RNA world are discussed.

Large transient fault current test of an electrical roll ring

NASA Technical Reports Server (NTRS)

Yenni, Edward J.; Birchenough, Arthur G.

1992-01-01

The space station uses precision rotary gimbals to provide for sun tracking of its photoelectric arrays. Electrical power, command signals and data are transferred across the gimbals by roll rings. Roll rings have been shown to be capable of highly efficient electrical transmission and long life, through tests conducted at the NASA Lewis Research Center and Honeywell's Satellite and Space Systems Division in Phoenix, AZ. Large potential fault currents inherent to the power system's DC distribution architecture, have brought about the need to evaluate the effects of large transient fault currents on roll rings. A test recently conducted at Lewis subjected a roll ring to a simulated worst case space station electrical fault. The system model used to obtain the fault profile is described, along with details of the reduced order circuit that was used to simulate the fault. Test results comparing roll ring performance before and after the fault are also presented.

Deflecting light into resonant cavities for spectroscopy

DOEpatents

Zare, R.N.; Martin, J.; Paldus, B.A.

1998-09-29

Light is coupled into a cavity ring down spectroscopy (CRDS) resonant cavity using an acousto-optic modulator. The AOM allows in-coupling efficiencies in excess of 40%, which is two to three orders of magnitude higher than in conventional systems using a cavity mirror for in-coupling. The AOM shutoff time is shorter than the roundtrip time of the cavity. The higher light intensities lead to a reduction in shot noise, and allow the use of relatively insensitive but fast-responding detectors such as photovoltaic detectors. Other deflection devices such as electro-optic modulators or elements used in conventional Q-switching may be used instead of the AOM. The method is particularly useful in the mid-infrared, far-infrared, and ultraviolet wavelength ranges, for which moderately reflecting input mirrors are not widely available. 5 figs.

Deflecting light into resonant cavities for spectroscopy

DOEpatents

Zare, Richard N.; Martin, Juergen; Paldus, Barbara A.

1998-01-01

Light is coupled into a cavity ring down spectroscopy (CRDS) resonant cavity using an acousto-optic modulator. The AOM allows in-coupling efficiencies in excess of 40%, which is two to three orders of magnitude higher than in conventional systems using a cavity mirror for in-coupling. The AOM shutoff time is shorter than the roundtrip time of the cavity. The higher light intensities lead to a reduction in shot noise, and allow the use of relatively insensitive but fast-responding detectors such as photovoltaic detectors. Other deflection devices such as electro-optic modulators or elements used in conventional Q-switching may be used instead of the AOM. The method is particularly useful in the mid-infrared, far-infrared, and ultraviolet wavelength ranges, for which moderately reflecting input mirrors are not widely available.

Ultrafast electron crystallography: Transient structures of molecules, surfaces, and phase transitions

PubMed Central

Ruan, Chong-Yu; Vigliotti, Franco; Lobastov, Vladimir A.; Chen, Songye; Zewail, Ahmed H.

2004-01-01

The static structure of macromolecular assemblies can be mapped out with atomic-scale resolution by using electron diffraction and microscopy of crystals. For transient nonequilibrium structures, which are critical to the understanding of dynamics and mechanisms, both spatial and temporal resolutions are required; the shortest scales of length (0.1–1 nm) and time (10–13 to 10–12 s) represent the quantum limit, the nonstatistical regime of rates. Here, we report the development of ultrafast electron crystallography for direct determination of structures with submonolayer sensitivity. In these experiments, we use crystalline silicon as a template for different adsorbates: hydrogen, chlorine, and trifluoroiodomethane. We observe the coherent restructuring of the surface layers with subangstrom displacement of atoms after the ultrafast heat impulse. This nonequilibrium dynamics, which is monitored in steps of 2 ps (total change ≤10 ps), contrasts that of the nanometer substrate. The effect of adsorbates and the phase transition at higher fluences were also studied through the evolution of streaks of interferences, Bragg spots (and their rocking curves), and rings in the diffraction patterns. We compare these results with kinematical theory and those of x-ray diffraction developed to study bulk behaviors. The sensitivity achieved here, with the 6 orders of magnitude larger cross section than x-ray diffraction, and with the capabilities of combined spatial (≈0.01 Å) and temporal (300–600 fs) resolutions, promise diverse applications for this ultrafast electron crystallography tabletop methodology. PMID:14745037

Down to the roughness scale assessment of piston-ring/liner contacts

NASA Astrophysics Data System (ADS)

Checo, H. M.; Jaramillo, A.; Ausas, R. F.; Jai, M.; Buscaglia, G. C.

2017-02-01

The effects of surface roughness in hydrodynamic bearings been accounted for through several approaches, the most widely used being averaging or stochastic techniques. With these the surface is not treated “as it is”, but by means of an assumed probability distribution for the roughness. The so called direct, deterministic or measured-surface simulation) solve the lubrication problem with realistic surfaces down to the roughness scale. This leads to expensive computational problems. Most researchers have tackled this problem considering non-moving surfaces and neglecting the ring dynamics to reduce the computational burden. What is proposed here is to solve the fully-deterministic simulation both in space and in time, so that the actual movement of the surfaces and the rings dynamics are taken into account. This simulation is much more complex than previous ones, as it is intrinsically transient. The feasibility of these fully-deterministic simulations is illustrated two cases: fully deterministic simulation of liner surfaces with diverse finishings (honed and coated bores) with constant piston velocity and load on the ring and also in real engine conditions.

Polycyclic aromatic hydrocarbons (PAHs) in water from three estuaries of China: Distribution, seasonal variations and ecological risk assessment.

PubMed

Yan, Jinxia; Liu, Jingling; Shi, Xuan; You, Xiaoguang; Cao, Zhiguo

2016-08-15

The distribution, seasonal variations and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in water from three estuaries in Hai River Basin of China, which has been suffering from different anthropogenic pressures, were investigated. In three estuaries, the average concentration of ΣPAHs was the lowest in Luan River estuary, followed by Hai River estuary, and the highest in Zhangweixin River estuary. There were significant seasonal variations in ΣPAHs, the concentrations of ΣPAHs were higher in November than in May and August. The composition profiles of PAHs in different sites were significantly different, and illustrated seasonal variations. Generally, 2-ring (Nap) and 3-ring PAHs (Acp, Fl and Phe) were the most abundant components at most sampling sites in three estuaries. The PAHs in three estuaries were mainly originated from pyrogenic sources. A method based on toxic equivalency factors (TEFs) and risk quotient (RQ) was proposed to assess the ecological risk of ΣPAHs, with the ecological risk of individual PAHs being considered separately. The results showed that the ecological risks caused by ΣPAHs were high in Hai River estuary and Zhangweixin River estuary, and moderate in Luan River estuary. The mean values of ecological risk in August were lower than those in November. The contributions of individual PAHs to ecological risk were different in May, August and November. 3-ring and 4-ring PAHs accounted for much more ecological risk than 2-ring, 5-ring and 6-ring, although the contributions of 5-ring and 6-ring to ecological risk were higher than these to PAHs concentrations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Platinum/zeolite catalyst for reforming n-hexane: Kinetic and mechanistic considerations

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

Lane, G.S.; Modica, F.S.; Miller, J.T.

A platinum/L-zeolite-reforming catalyst exhibits activity and selectivity for converting n-hexane into benzene than other Pt catalyst. The reaction pathways indicate that for all catalysts, e.g., Pt/K L or Pt/K Y, benzene is formed as a primary product by one-six-ring closure and methylcyclopentane is formed as a primary product via one-five-ring closure. The ratio for one-six to one-five-ring closure, however, is about two times greater for the Pt/K L than for the Pt/K Y, or other platinum catalysts. The preference for the one-six-ring closure in L zeolite appears to be related to the optimum pore size of the L zeolite. Inmore » addition to an increased selectivity for one-six-ring closure, the Pt/K L-zeolite catalyst also displays increased reactivity. For example, the turnover frequency of the Pt/K L-zeolite catalyst is 10 times higher for formation of benzene and 3.3 times higher for formation of methylcyclopentane compared with the Pt/K Y-zeolite catalyst. Although the Pt/K L is more reactive than Pt/K Y, the apparent activation energies, 54 kcal/mol for one-six-ring closure and 39 kcal/mol for one-five-ring closure, are the same for both catalysts. Differences in reactivity are associated with an increase in the preexponential term for the Pt/K L catalyst. The increased aromatics selectivity for Pt/K L is consistent with the confinement model which proposes that n-hexane is adsorbed as a six-ring pseudo-cycle resembling the transition state for one-six-ring closure.« less

Diverse trends of electron correlation effects for properties with different radial and angular factors in an atomic system: a case study in Ca+

NASA Astrophysics Data System (ADS)

Kumar, Pradeep; Li, Cheng-Bin; Sahoo, B. K.

2018-03-01

Dependencies of electron correlation effects with the rank and radial behavior of spectroscopic properties are analyzed in the singly charged calcium ion (Ca+). To demonstrate these trends, we have determined field shift constants, magnetic dipole and electric quadrupole hyperfine structure constants, Landé g J factors, and electric quadrupole moments that are described by electronic operators with different radial and angular factors. Radial dependencies are investigated by comparing correlation trends among the properties that have similar angular factors and vice versa. To highlight these observations, we present results from the mean-field approach to all-orders along with intermediate contributions. Contributions from higher relativistic corrections are also given. These findings suggest that sometime lower-order approximations can give results agreeing with the experimental results, but inclusion of some of higher-order correlation effects can cause large disagreement with the experimental values. Therefore, validity of a method for accurate evaluation of atomic properties can be tested by performing calculations of several properties simultaneously that have diverse dependencies on the angular and radial factors and comparing with the available experimental results. Nevertheless, it is imperative to include full triple and quadrupole excitations in the all-order many-body methods for high-precision calculations that are yet to be developed adopting spherical coordinate system for atomic studies.

Coherence resonance and stochastic resonance in directionally coupled rings

NASA Astrophysics Data System (ADS)

Werner, Johannes Peter; Benner, Hartmut; Florio, Brendan James; Stemler, Thomas

2011-11-01

In coupled systems, symmetry plays an important role for the collective dynamics. We investigate the dynamical response to noise with and without weak periodic modulation for two classes of ring systems. Each ring system consists of unidirectionally coupled bistable elements but in one class, the number of elements is even while in the other class the number is odd. Consequently, the rings without forcing show at a certain coupling strength, either ordering (similar to anti-ferromagnetic chains) or auto-oscillations. Analysing the bifurcations and fixed points of the two ring classes enables us to explain the dynamical response measured to noise and weak modulation. Moreover, by analysing a simplified model, we demonstrate that the response is universal for systems having a directional component in their stochastic dynamics in phase space around the origin.

In situ measurements of Saturn’s ionosphere show that it is dynamic and interacts with the rings

NASA Astrophysics Data System (ADS)

Wahlund, J.-E.; Morooka, M. W.; Hadid, L. Z.; Persoon, A. M.; Farrell, W. M.; Gurnett, D. A.; Hospodarsky, G.; Kurth, W. S.; Ye, S.-Y.; Andrews, D. J.; Edberg, N. J. T.; Eriksson, A. I.; Vigren, E.

2018-01-01

The ionized upper layer of Saturn’s atmosphere, its ionosphere, provides a closure of currents mediated by the magnetic field to other electrically charged regions (for example, rings) and hosts ion-molecule chemistry. In 2017, the Cassini spacecraft passed inside the planet’s rings, allowing in situ measurements of the ionosphere. The Radio and Plasma Wave Science instrument detected a cold, dense, and dynamic ionosphere at Saturn that interacts with the rings. Plasma densities reached up to 1000 cubic centimeters, and electron temperatures were below 1160 kelvin near closest approach. The density varied between orbits by up to two orders of magnitude. Saturn’s A- and B-rings cast a shadow on the planet that reduced ionization in the upper atmosphere, causing a north-south asymmetry.

Multi-way multi-group segregation and diversity indices.

PubMed

Gorelick, Root; Bertram, Susan M

2010-06-01

How can we compute a segregation or diversity index from a three-way or multi-way contingency table, where each variable can take on an arbitrary finite number of values and where the index takes values between zero and one? Previous methods only exist for two-way contingency tables or dichotomous variables. A prototypical three-way case is the segregation index of a set of industries or departments given multiple explanatory variables of both sex and race. This can be further extended to other variables, such as disability, number of years of education, and former military service. We extend existing segregation indices based on Euclidean distance (square of coefficient of variation) and Boltzmann/Shannon/Theil index from two-way to multi-way contingency tables by including multiple summations. We provide several biological applications, such as indices for age polyethism and linkage disequilibrium. We also provide a new heuristic conceptualization of entropy-based indices. Higher order association measures are often independent of lower order ones, hence an overall segregation or diversity index should be the arithmetic mean of the normalized association measures at all orders. These methods are applicable when individuals self-identify as multiple races or even multiple sexes and when individuals work part-time in multiple industries. The policy implications of this work are enormous, allowing people to rigorously test whether employment or biological diversity has changed.

An organismal view of dendrochronology

Treesearch

Kevin T. Smith

2008-01-01

An organism is the most basic unit of independent life. The tree-ring record is defined by organismal processes. Dendrochronology contributes to investigations far removed from organismal biology, e.g., archeology, climatology, disturbance ecology, etc. The increasing integration of dendrochronology into a diverse research community suggests an opportunity for a brief...

Genetic diversity of papaya ring spot virus in Puerto Rico

USDA-ARS?s Scientific Manuscript database

The Food and Agriculture Organization estimates that 20-40% of crop yield is lost due to pests and diseases. Viruses are agents that cause diseases which contribute greatly to the global yield loss. Because of this, food production is negatively affected, especially in the tropics. Carica papaya, co...

[beta]-Lactamases in the Biochemistry and Molecular Biology Laboratory

ERIC Educational Resources Information Center

Amador, Paula; Prudencio, Cristina; Vieira, Monica; Ferraz, Ricardo; Fonte, Rosalia; Silva, Nuno; Coelho, Pedro; Fernandes, Ruben

2009-01-01

[beta]-lactamases are hydrolytic enzymes that inactivate the [beta]-lactam ring of antibiotics such as penicillins and cephalosporins. The major diversity of studies carried out until now have mainly focused on the characterization of [beta]-lactamases recovered among clinical isolates of Gram-positive staphylococci and Gram-negative…

Mapping Ring Particle Cooling across Saturn's Rings with Cassini CIRS

NASA Astrophysics Data System (ADS)

Brooks, Shawn M.; Spilker, L. J.; Edgington, S. G.; Pilorz, S. H.; Deau, E.

2010-10-01

Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and quick temperature responses are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid, coherent particles can be expected to have higher thermal inertias (Ferrari et al. 2005). Cassini's Composite Infrared Spectrometer has recorded millions of spectra of Saturn's rings since its arrival at Saturn in 2004 (personal communication, M. Segura). CIRS records far infrared radiation between 10 and 600 cm-1 (16.7 and 1000 µm) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn's rings peaks in this wavelength range. FP1 spectra can be used to infer ring temperatures. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The thermal budget of the rings is dominated by the solar radiation absorbed by its constituent particles. When ring particles enter Saturn's shadow this source of energy is abruptly cut off. As a result, ring particles cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

Morphological Diversity of the Colony Produced by Bacteria Proteus mirabilis

NASA Astrophysics Data System (ADS)

Nakahara, Akio; Shimada, Yuji; Wakita, Jun-ichi; Matsushita, Mitsugu; Matsuyama, Tohey

1996-08-01

Morphological changes of colonies have been investigatedfor a bacterial strain of Proteus mirabilis, which is a famous speciesfor producing concentric-ring-like colonies. It was found that colony patterns can be classified into three types,i.e., cyclic spreading, diffusion-limited growth (DLA-like)and three-dimensional growth (inside the agar medium) patterns. Cyclic spreading patterns can further be classifiedinto three subgroups, i.e., concentric-ring, homogeneous and spatiotemporal patterns. These subgroups were classified by examining the development of colony structure after colonies spread all over petri-dishes. Comparison of the results with thoseof another bacterial species Bacillus subtilis is also discussed.

Synthetic Aziridines in Medicinal Chemistry: A Mini-Review.

PubMed

Singh, Girija S

2016-01-01

Azaheterocyclic compounds are well-known to have diverse types of biological activity. Among them, azacyclopropanes, commonly referred as aziridines, occupy a prominent place in synthetic organic and medicinal chemistry due to its occurrence in natural resources, complexity involved in synthesis due to ring-strain, building blocks in organic synthesis, and its biological properties. Several novel compounds containing aziridine ring have been designed and synthesized recently by medicinal chemists for evaluating their biological profile. A number of compounds are reported as cysteine protease inhibitors, antibacterial, antifungal, anticancer, antileishmanial, and antimalarial agents. This review article summarizes the biological activity of such compounds. The preparation of such compounds is also described.

The Role of Tetraether Lipid Composition in the Adaptation of Thermophilic Archaea to Acidity

PubMed Central

Boyd, Eric S.; Hamilton, Trinity L.; Wang, Jinxiang; He, Liu; Zhang, Chuanlun L.

2013-01-01

Diether and tetraether lipids are fundamental components of the archaeal cell membrane. Archaea adjust the degree of tetraether lipid cyclization in order to maintain functional membranes and cellular homeostasis when confronted with pH and/or thermal stress. Thus, the ability to adjust tetraether lipid composition likely represents a critical phenotypic trait that enabled archaeal diversification into environments characterized by extremes in pH and/or temperature. Here we assess the relationship between geochemical variation, core- and polar-isoprenoid glycerol dibiphytanyl glycerol tetraether (C-iGDGT and P-iGDGT, respectively) lipid composition, and archaeal 16S rRNA gene diversity and abundance in 27 geothermal springs in Yellowstone National Park, Wyoming. The composition and abundance of C-iGDGT and P-iGDGT lipids recovered from geothermal ecosystems were distinct from surrounding soils, indicating that they are synthesized endogenously. With the exception of GDGT-0 (no cyclopentyl rings), the abundances of individual C-iGDGT and P-iGDGT lipids were significantly correlated. The abundance of a number of individual tetraether lipids varied positively with the relative abundance of individual 16S rRNA gene sequences, most notably crenarchaeol in both the core and polar GDGT fraction and sequences closely affiliated with Candidatus Nitrosocaldus yellowstonii. This finding supports the proposal that crenarchaeol is a biomarker for nitrifying archaea. Variation in the degree of cyclization of C- and P-iGDGT lipids recovered from geothermal mats and sediments could best be explained by variation in spring pH, with lipids from acidic environments tending to have, on average, more internal cyclic rings than those from higher pH ecosystems. Likewise, variation in the phylogenetic composition of archaeal 16S rRNA genes could best be explained by spring pH. In turn, the phylogenetic similarity of archaeal 16S rRNA genes was significantly correlated with the similarity in the composition of C- and P-iGDGT lipids. Taken together, these data suggest that the ability to adjust the composition of GDGT lipid membranes played a central role in the diversification of archaea into or out of environments characterized by extremes of low pH and high temperature. PMID:23565112

Physical and Thermal Comfort Properties of Viscose Fabrics made from Vortex and Ring Spun Yarns

NASA Astrophysics Data System (ADS)

Thilagavathi, G.; Muthukumar, N.; Kumar, V. Kiran; Sadasivam, Sanjay; Sidharth, P. Mithun; Nikhil Jain, G.

2017-06-01

Viscose fiber is frequently preferred for various types of inner and outer knitwear products for its comfort and visual characteristics. In this study, the physical and thermal comfort properties of viscose fabrics made from ring and vortex yarns have been studied to explore the impact of spinning process on fabric properties. 100% viscose fibers were spun into yarns by ring and vortex spinning and the developed yarns were converted to single jersey fabrics. The results indicated that fabrics made from vortex spun yarns had better pilling resistance over that of those from ring spun yarns. There was no significant difference between bursting strength values of vortex and ring spun yarn fabrics. Fabrics made from ring yarn had better dimensional stability compared to fabrics made from vortex yarn. The air permeability and water vapour permeability of vortex yarn fabrics were higher than ring spun yarn fabrics. The vortex yarn fabrics had better thermal comfort properties compared to ring yarn fabrics.

Tunable room temperature THz sources based on nonlinear mixing in a hybrid optical and THz micro-ring resonator.

PubMed

Sinha, Raju; Karabiyik, Mustafa; Al-Amin, Chowdhury; Vabbina, Phani K; Güney, Durdu Ö; Pala, Nezih

2015-03-24

We propose and systematically investigate a novel tunable, compact room temperature terahertz (THz) source based on difference frequency generation in a hybrid optical and THz micro-ring resonator. We describe detailed design steps of the source capable of generating THz wave in 0.5-10 THz with a tunability resolution of 0.05 THz by using high second order optical susceptibility (χ((2))) in crystals and polymers. In order to enhance THz generation compared to bulk nonlinear material, we employ a nonlinear optical micro-ring resonator with high-Q resonant modes for infrared input waves. Another ring oscillator with the same outer radius underneath the nonlinear ring with an insulation of SiO2 layer supports the generated THz with resonant modes and out-couples them into a THz waveguide. The phase matching condition is satisfied by engineering both the optical and THz resonators with appropriate effective indices. We analytically estimate THz output power of the device by using practical values of susceptibility in available crystals and polymers. The proposed source can enable tunable, compact THz emitters, on-chip integrated spectrometers, inspire a broader use of THz sources and motivate many important potential THz applications in different fields.

Tunable Room Temperature THz Sources Based on Nonlinear Mixing in a Hybrid Optical and THz Micro-Ring Resonator

PubMed Central

Sinha, Raju; Karabiyik, Mustafa; Al-Amin, Chowdhury; Vabbina, Phani K.; Güney, Durdu Ö.; Pala, Nezih

2015-01-01

We propose and systematically investigate a novel tunable, compact room temperature terahertz (THz) source based on difference frequency generation in a hybrid optical and THz micro-ring resonator. We describe detailed design steps of the source capable of generating THz wave in 0.5–10 THz with a tunability resolution of 0.05 THz by using high second order optical susceptibility (χ(2)) in crystals and polymers. In order to enhance THz generation compared to bulk nonlinear material, we employ a nonlinear optical micro-ring resonator with high-Q resonant modes for infrared input waves. Another ring oscillator with the same outer radius underneath the nonlinear ring with an insulation of SiO2 layer supports the generated THz with resonant modes and out-couples them into a THz waveguide. The phase matching condition is satisfied by engineering both the optical and THz resonators with appropriate effective indices. We analytically estimate THz output power of the device by using practical values of susceptibility in available crystals and polymers. The proposed source can enable tunable, compact THz emitters, on-chip integrated spectrometers, inspire a broader use of THz sources and motivate many important potential THz applications in different fields. PMID:25800287

The Case for Massive and Ancient Rings of Saturn

NASA Astrophysics Data System (ADS)

Esposito, Larry W.

2016-04-01

Analysis of Voyager and Pioneer 11 results give a mass for Saturn's rings, M = 5 x 10-8 Msat. This is about the mass of Saturn's small moon Mimas. This has been interpreted as a lower limit to the ring mass (Esposito et al 1983), since the thickest parts of the rings were not penetrated by the stellar occultstion, and this calculation assumes an unvarying particle size throughout the rings. Because the rings are constantly bombarded by micrometeroids, their current composition of nearly pure water ice implies such low mass rings must have formed recently. The case is par-ticularly strong for Saturn's A ring, where the data are the best, implying the A ring is less than 10% of the age of the Saturn (Esposito 1986). Cassini results com-pound this problem. UVIS spectra are consistent with either young rings or rings about 10x as massive as the Voyager estimate (Elliott and Esposito (2011). CDA confirms the impacting mass flux is similar to that as-sumed for the pollution calculations (Kempf etal 2015). VIMS analysis of density wave signatures in the B ring gives a value of about 1/3 the Voyager value (Hedmann etal 2016). This VIMS result implies the rings are even younger! The problem is that young rings are very unlikely to be formed recently, meaning that we live in a very special epoch, following some unlikely recent origin… like disruption of a medium sized moon or capture of the fragments of a disrupted comet. This paradox (Charnoz etal 2009) is unre-solved. Alternative interpretations: To take the VIMS results at face value, Saturn's low mass rings must be very young. The optically thick B ring must be made of small, porous or fractal particles. This is hard to understand, since the particles are continually colliding every few hours and temporary aggregates will stir the collision velocities to higher values. An alternative is that we accept the higher mass interpretation of the Pioneer 11 results (Esposito etal 2008) using the granola bar model of Colwell etal 2007. This would imply that the density wave structure seen by VIMS is not sensing all the mass in the rings, where structure near strong resonances is dominted by temporary aggregates, and where non-linear effects cause the parti-cles to jam (Lewis and Stewart 2009). The density waves may be seeing the mass density in the gaps be-tween self-gravity wakes, whose optical depth is roughly contant and considerably lower than the total B ring opacity (Colwell etal 2007). These massive rings would be consistent with the origin model of Canup (2011) where a Titan-sized diffferntiated moon was disrupted early in Saturn's formation.

Self-organization of granular media in airborne ultrasonic fields

NASA Astrophysics Data System (ADS)

Bobrovskaya, A. I.; Stepanenko, D. A.; Minchenya, V. T.

2012-05-01

The article presents results of experimental and theoretical studies of behaviour of granular media (powder materials) in airborne ultrasonic field created by flexurally-vibrating ring-shaped waveguide with resonant frequency in the range 20-40 kHz. Experiments show that action of acoustic radiation forces results in formation of ordered structures in the form of ultrathin walls (monolayers) with number corresponding to the number of ring nodal points. Action of secondary radiation forces (König forces) results in formation of collateral (secondary) walls situated nearby primary walls. Experimental observations are compared with results of modelling of acoustic radiation force field inside the ring by means of COMSOL Multiphysics and MathCad software. Results of the studies can be used in development of devices for ultrasonic separation and concentration of particles as well as for formation of ordered monolayers from spherical particles.

Compact Dual-Band Bandpass Filter Using Stubs Loaded Ring Resonator

NASA Astrophysics Data System (ADS)

Xu, Jin

2016-01-01

This paper presents a novel second-order dual-band bandpass filter (BPF) by using proposed stubs loaded ring resonator. The resonant behavior of proposed stubs loaded ring resonator is analyzed by even-/odd-mode method, which shows its multiple-mode resonant characteristic. Parameters sweep is done so as to give the design guidelines. As an example, a second-order dual-band BPF operating at 1.8/5.2 GHz for GSM and WLAN applications is designed, fabricated and measured. The fabricated filter has a very compact size of 0.05λg×0.15λg. Measured results also show that the proposed dual-band BPF has a better than 20 dB rejection upper stopband from 5.47 GHz to 12.56 GHz. Good agreement is shown between the simulated and measured results.

Acoustic radiation force optical coherence elastography using vibro-acoustography

NASA Astrophysics Data System (ADS)

Qu, Yueqiao (.; Ma, Teng; Li, Rui; Qi, Wenjuan; Zhu, Jiang; He, Youmin; Shung, K. K.; Zhou, Qifa; Chen, Zhongping

2015-03-01

High-resolution elasticity mapping of tissue biomechanical properties is crucial in early detection of many diseases. We report a method of acoustic radiation force optical coherence elastography (ARF-OCE) based on the methods of vibroacoustography, which uses a dual-ring ultrasonic transducer in order to excite a highly localized 3-D field. The single element transducer introduced previously in our ARF imaging has low depth resolution because the ARF is difficult to discriminate along the entire ultrasound propagation path. The novel dual-ring approach takes advantage of two overlapping acoustic fields and a few-hundred-Hertz difference in the signal frequencies of the two unmodulated confocal ring transducers in order to confine the acoustic stress field within a smaller volume. This frequency difference is the resulting "beating" frequency of the system. The frequency modulation of the transducers has been validated by comparing the dual ring ARF-OCE measurement to that of the single ring using a homogeneous silicone phantom. We have compared and analyzed the phantom resonance frequency to show the feasibility of our approach. We also show phantom images of the ARF-OCE based vibro-acoustography method and map out its acoustic stress region. We concluded that the dual-ring transducer is able to better localize the excitation to a smaller region to induce a focused force, which allows for highly selective excitation of small regions. The beat-frequency elastography method has great potential to achieve high-resolution elastography for ophthalmology and cardiovascular applications.

High-Accuracy Ring Laser Gyroscopes: Earth Rotation Rate and Relativistic Effects

NASA Astrophysics Data System (ADS)

Beverini, N.; Di Virgilio, A.; Belfi, J.; Ortolan, A.; Schreiber, K. U.; Gebauer, A.; Klügel, T.

2016-06-01

The Gross Ring G is a square ring laser gyroscope, built as a monolithic Zerodur structure with 4 m length on all sides. It has demonstrated that a large ring laser provides a sensitivity high enough to measure the rotational rate of the Earth with a high precision of ΔΩE < 10-8. It is possible to show that further improvement in accuracy could allow the observation of the metric frame dragging, produced by the Earth rotating mass (Lense-Thirring effect), as predicted by General Relativity. Furthermore, it can provide a local measurement of the Earth rotational rate with a sensitivity near to that provided by the international system IERS. The GINGER project is intending to take this level of sensitivity further and to improve the accuracy and the long-term stability. A monolithic structure similar to the G ring laser is not available for GINGER. Therefore the preliminary goal is the demonstration of the feasibility of a larger gyroscope structure, where the mechanical stability is obtained through an active control of the geometry. A prototype moderate size gyroscope (GP-2) has been set up in Pisa in order to test this active control of the ring geometry, while a second structure (GINGERino) has been installed inside the Gran Sasso underground laboratory in order to investigate the properties of a deep underground laboratory in view of an installation of a future GINGER apparatus. The preliminary data on these two latter instruments are presented.

Conclusions and recommendations: Exploration of the Saturn system

NASA Technical Reports Server (NTRS)

Hunten, D. M.

1978-01-01

Saturn missions have the following principal goals, in order of importance: (1) Intensive investigation of the atmosphere of Saturn; (2) determination of regional surface chemistry and properties of the surface features of satellites and properties of ring particles; (3) intensive investigation of Titan; and (4) atmospheric dynamics and structure of Saturn satellites and Saturn rings.

Growth ring formation in the starch granules of potato tubers.

PubMed

Pilling, Emma; Smith, Alison M

2003-05-01

Starch granules from higher plants contain alternating zones of semicrystalline and amorphous material known as growth rings. The regulation of growth ring formation is not understood. We provide several independent lines of evidence that growth ring formation in the starch granules of potato (Solanum tuberosum) tubers is not under diurnal control. Ring formation is not abolished by growth in constant conditions, and ring periodicity and appearance are relatively unaffected by a change from a 24-h to a 40-h photoperiod, and by alterations in substrate supply to the tuber that are known to affect the diurnal pattern of tuber starch synthesis. Some, but not all, of the features of ring formation are consistent with the involvement of a circadian rhythm. Such a rhythm might operate by changing the relative activities of starch-synthesizing enzymes: Growth ring formation is disrupted in tubers with reduced activity of a major isoform of starch synthase. We suggest that physical as well as biological mechanisms may contribute to the control of ring formation, and that a complex interplay of several factors may by involved.

Growth Ring Formation in the Starch Granules of Potato Tubers1

PubMed Central

Pilling, Emma; Smith, Alison M.

2003-01-01

Starch granules from higher plants contain alternating zones of semicrystalline and amorphous material known as growth rings. The regulation of growth ring formation is not understood. We provide several independent lines of evidence that growth ring formation in the starch granules of potato (Solanum tuberosum) tubers is not under diurnal control. Ring formation is not abolished by growth in constant conditions, and ring periodicity and appearance are relatively unaffected by a change from a 24-h to a 40-h photoperiod, and by alterations in substrate supply to the tuber that are known to affect the diurnal pattern of tuber starch synthesis. Some, but not all, of the features of ring formation are consistent with the involvement of a circadian rhythm. Such a rhythm might operate by changing the relative activities of starch-synthesizing enzymes: Growth ring formation is disrupted in tubers with reduced activity of a major isoform of starch synthase. We suggest that physical as well as biological mechanisms may contribute to the control of ring formation, and that a complex interplay of several factors may by involved. PMID:12746541

A pulsed jumping ring apparatus for demonstration of Lenz's law

NASA Astrophysics Data System (ADS)

Tanner, Paul; Loebach, Jeff; Cook, James; Hallen, H. D.

2001-08-01

Lenz's law is often demonstrated in classrooms by the use of Elihu Thomson's jumping ring. However, it is ironic that a thorough analysis of the physics of the ac jumping ring reveals that the operation is due mainly to a phase difference, not Lenz's law. A complete analysis of the physics behind the ac jumping ring is difficult for the introductory student. We present a design for a pulsed jumping ring which can be fully described by the application of Lenz's law. Other advantages of this system are that it lends itself to a rigorous analysis of the force balances and energy flow. The simple jumping ring apparatus closely resembles Thomson's, but is powered by a capacitor bank. The jump heights were measured for several rings as a function of energy stored in the capacitors. A simple model describes the data well. Currents in both the drive coil and ring are measured and that of the drive coil modeled to illuminate some properties of the capacitors. An analysis of the energy flow in the system explains the higher jump heights, to 2 m, when the ring is cooled.

Laser collisional induced fluorescence electron density measurements as a function of ring bias and the onset of anode spot formation in a ring cusp magnetic field

NASA Astrophysics Data System (ADS)

Arthur, N. A.; Foster, J. E.; Barnat, E. V.

2018-05-01

Two-dimensional electron density measurements are made in a magnetic ring cusp discharge using laser collisional induced fluorescence. The magnet rings are isolated from the anode structure such that they can be biased independently in order to modulate electron flows through the magnetic cusps. Electron density images are captured as a function of bias voltage in order to assess the effects of current flow through the cusp on the spatial extent of the cusp. We anticipated that for a fixed current density being funneled through the magnetic cusp, the leak width would necessarily increase. Unexpectedly, the leak width, as measured by LCIF images, does not increase. This suggests that the current density is not constant, and that possibly either electrons are being heated or additional ionization events are occurring within the cusp. Spatially resolving electron temperature would be needed to determine if electrons are being heated within the cusp. We also observe breakdown of the anode magnetosheath and formation of anode spots at high bias voltage.

Towards a theory for Neptune's arc rings

NASA Technical Reports Server (NTRS)

Goldreich, P.; Tremaine, S.; Borderies, N.

1986-01-01

It is proposed that the incomplete rings of Neptune consist of a number of short arcs centered on the corotation resonances of a single satellite. The satellite must have a radius of the order of 100 km or more and move on an inclined orbit. Corotation resonances are located at potential maxima. Thus, mechanical energy dissipated by interparticle collisions must be continually replenished to prevent the arcs from spreading. It is shown that each corotation resonance is associated with a nearby Lindblad resonance, which excites the ring particles' orbital eccentricity, thus supplying the energy required to maintain the arc. The ultimate energy reservoir is the satellite's orbital energy. Therefore, interaction with the arcs damps the satellite's orbital inclination. The self-gravity of the arcs limits their contraction and enforces a relation between arc length and mass. The estimated arc masses are so small, of the order of 10 to the 16th g, that the satellite's orbital inclination suffers negligible decay over the age of the solar system. The inferred surface mass densities are comparable to those found in the major rings of Saturn and Uranus.

Increasing Critical Thinking Skills To Improve Problem-Solving Ability in Mathematics.

ERIC Educational Resources Information Center

Jackson, Louise

This report investigated to what extent a curriculum designed to actively teach critical thinking skills resulted in students utilizing higher-order thinking skills (e.g., analysis, synthesis and evaluation). An intervention strategy was designed for a sixth grade class located in a diverse suburban community in northern Illinois. The intervention…

A Framework to Embed Communication Skills across the Curriculum: A Design-Based Research Approach

ERIC Educational Resources Information Center

Johnson, Steve; Veitch, Sarah; Dewiyanti, Silvia

2015-01-01

There is widespread recognition that universities are now delivering higher education to diverse student populations with very different needs and aspirations from the more traditional cohorts of the past. In order to prepare students for a broad range of employment opportunities, universities are also fostering the development of "graduate…

Building Capacity through International Student Affairs Exchange

ERIC Educational Resources Information Center

Roberts, Dennis C.; Roberts, Darbi L.

2012-01-01

In order to build local capacity in an international higher education setting, the Qatar Study Tour and Young Professionals Institute (QST and YPI) was created as an inquiry-based learning experience shared among diverse participants and designed to enhance learning at both the local and international levels. The intent of the QST and YPI model…

Fostering Higher Order Critical Thinking in 21st Century Teachers

ERIC Educational Resources Information Center

Taft, Mary Miller

2012-01-01

Teachers working with increasingly diverse student populations are expected, for the first time in American history, to bring all students to high levels of proficiency. American graduates must compete with graduates from other nations, given the realities of the 21st century global economy. American teachers must possess 21st century skills in…

A New Kind of Affirmative Action Can Ensure Diversity

ERIC Educational Resources Information Center

Kahlenberg, Richard D.

2012-01-01

After almost a half century, American higher education's use of racial preferences in admissions to selective colleges may well be coming to an end. The good news for people concerned about racial and economic justice is that in several states that have banned racial affirmative action by voter referendum or executive order, legislators and…

Real-World Reading and Writing through Project-Based Learning.

ERIC Educational Resources Information Center

Diffily, Deborah

Standards documents produced by professional educational organizations on the best ways to teach reading and writing have been synthesized by Zemelman, Daniels, and Hyde (1998). They recommend that teachers provide: more active learning in the classroom; more diverse roles for teachers; more emphasis on higher order thinking; more deep study of a…

Gender Differences in Career Satisfaction among Postsecondary Faculty in Stem Disciplines

ERIC Educational Resources Information Center

Martin, Cynthia L.

2011-01-01

While years of effort to attract more women into higher education careers in science, technology, engineering, and mathematics (collectively known as STEM disciplines) has shown some success, retaining women faculty once they are hired has been much less successful. Their retention is essential in order to maintain diversity among faculty.…

A Proposed Framework for Global Leadership Education: Learning Objectives and Curricula

ERIC Educational Resources Information Center

Brown, LeAnn M.; Whitaker, Brett L.; Brungardt, Curtis L.

2012-01-01

Many traditional leadership education paradigms are challenged by the transformational nature of globalization and are limited in application in diverse and complex contexts. In order to address these issues, a new framework must be adopted within higher education leadership programs to educate the next generation of global leaders. This paper…

Dynamics in microbial communities: Unraveling mechanisms to identify principles

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

Konopka, Allan; Lindemann, Stephen R.; Fredrickson, Jim K.

2015-07-01

Diversity begets higher order properties such as functional stability and robustness in microbial communities, but principles that inform conceptual (and eventually predictive) models of community dynamics are lacking. Recent work has shown that selection as well as dispersal and drift shape communities, but the mechanistic bases for assembly of communities and the forces that maintain their function in the face of environmental perturbation are not well understood. Conceptually, some interactions among community members could generate endogenous dynamics in composition, even in the absence of environmental changes. These endogenous dynamics are further perturbed by exogenous forcing factors to produce a richermore » network of community interactions, and it is this “system” that is the basis for higher order community properties. Elucidation of principles that follow from this conceptual model requires identifying the mechanisms that (a) optimize diversity within a community and (b) impart community stability. The network of interactions between organisms can be an important element by providing a buffer against disturbance beyond the effect of functional redundancy, as alternative pathways with different combinations of microbes can be recruited to fulfill specific functions.« less

The diversity of Klebsiella pneumoniae surface polysaccharides.

PubMed

Follador, Rainer; Heinz, Eva; Wyres, Kelly L; Ellington, Matthew J; Kowarik, Michael; Holt, Kathryn E; Thomson, Nicholas R

2016-08-01

Klebsiella pneumoniae is considered an urgent health concern due to the emergence of multi-drug-resistant strains for which vaccination offers a potential remedy. Vaccines based on surface polysaccharides are highly promising but need to address the high diversity of surface-exposed polysaccharides, synthesized as O-antigens (lipopolysaccharide, LPS) and K-antigens (capsule polysaccharide, CPS), present in K. pneumoniae . We present a comprehensive and clinically relevant study of the diversity of O- and K-antigen biosynthesis gene clusters across a global collection of over 500 K. pneumoniae whole-genome sequences and the seroepidemiology of human isolates from different infection types. Our study defines the genetic diversity of O- and K-antigen biosynthesis cluster sequences across this collection, identifying sequences for known serotypes as well as identifying novel LPS and CPS gene clusters found in circulating contemporary isolates. Serotypes O1, O2 and O3 were most prevalent in our sample set, accounting for approximately 80 % of all infections. In contrast, K serotypes showed an order of magnitude higher diversity and differ among infection types. In addition we investigated a potential association of O or K serotypes with phylogenetic lineage, infection type and the presence of known virulence genes. K1 and K2 serotypes, which are associated with hypervirulent K. pneumoniae , were associated with a higher abundance of virulence genes and more diverse O serotypes compared to other common K serotypes.

The diversity of Klebsiella pneumoniae surface polysaccharides

PubMed Central

Heinz, Eva; Wyres, Kelly L.; Ellington, Matthew J.; Kowarik, Michael; Holt, Kathryn E.; Thomson, Nicholas R.

2016-01-01

Klebsiella pneumoniae is considered an urgent health concern due to the emergence of multi-drug-resistant strains for which vaccination offers a potential remedy. Vaccines based on surface polysaccharides are highly promising but need to address the high diversity of surface-exposed polysaccharides, synthesized as O-antigens (lipopolysaccharide, LPS) and K-antigens (capsule polysaccharide, CPS), present in K. pneumoniae. We present a comprehensive and clinically relevant study of the diversity of O- and K-antigen biosynthesis gene clusters across a global collection of over 500 K. pneumoniae whole-genome sequences and the seroepidemiology of human isolates from different infection types. Our study defines the genetic diversity of O- and K-antigen biosynthesis cluster sequences across this collection, identifying sequences for known serotypes as well as identifying novel LPS and CPS gene clusters found in circulating contemporary isolates. Serotypes O1, O2 and O3 were most prevalent in our sample set, accounting for approximately 80 % of all infections. In contrast, K serotypes showed an order of magnitude higher diversity and differ among infection types. In addition we investigated a potential association of O or K serotypes with phylogenetic lineage, infection type and the presence of known virulence genes. K1 and K2 serotypes, which are associated with hypervirulent K. pneumoniae, were associated with a higher abundance of virulence genes and more diverse O serotypes compared to other common K serotypes. PMID:28348868

Analysis of the ecological water diversion project in Wenzhou City

NASA Astrophysics Data System (ADS)

Xu, Haibo; Fu, Lei; Lin, Tong

2018-02-01

As a developed city in China, Wenzhou City has been suffered from bad water quality for years. In order to improve the river network water quality, an ecological water diversion project was designed and executed by the regional government. In this study, an investigation and analysis of the regional ecological water diversion project is made for the purpose of examining the water quality improvements. A numerical model is also established, different water diversion flow rates and sewer interception levels are considered during the simulation. Simulation results reveal that higher flow rate and sewer interception level will greatly improve the river network water quality in Wenzhou City. The importance of the flow rate and interception level has been proved and future work will be focused on increasing the flow rate and upgrading the sewer interception level.

Moiré patterns in doubly differential electron-momentum distributions in atomic ionization by mid-infrared lasers

NASA Astrophysics Data System (ADS)

Dran, Martín; Arbó, Diego G.

2018-05-01

We analyze the doubly differential electron momentum distribution in above-threshold ionization of atomic hydrogen by a linearly polarized mid-infrared laser pulse. We reproduce side rings in the momentum distribution with forward-backward symmetry previously observed by Lemell et al. [Phys. Rev. A 87, 013421 (2013), 10.1103/PhysRevA.87.013421], whose origin, as far as we know, has not been explained so far. By developing a Fourier theory of moiré patterns, we demonstrate that such structures stem from the interplay between intra- and intercycle interference patterns which work as two separate grids in the two-dimensional momentum domain. We use a three-dimensional (3D) description based on the saddle-point approximation (SPA) to unravel the nature of these structures. When the periods of the two grids (intra- and intercycle) are similar, principal moiré patterns arise symmetrically as concentric rings in the forward and backward directions at high electron kinetic energy. Higher order moiré patterns are observed and characterized when the period of one grid is multiple of the other. We find a scale law for the position (in momentum space) of the center of the moiré rings in the tunneling regime. We verify the SPA predictions by comparison with time-dependent distorted-wave strong-field approximation calculations and the solutions of the full 3D time-dependent Schrödinger equation.

Athermal silicon optical add-drop multiplexers based on thermo-optic coefficient tuning of sol-gel material.

PubMed

Namnabat, Soha; Kim, Kyung-Jo; Jones, Adam; Himmelhuber, Roland; DeRose, Christopher T; Trotter, Douglas C; Starbuck, Andrew L; Pomerene, Andrew; Lentine, Anthony L; Norwood, Robert A

2017-09-04

Silicon photonics has gained interest for its potential to provide higher efficiency, bandwidth and reduced power consumption compared to electrical interconnects in datacenters and high performance computing environments. However, it is well known that silicon photonic devices suffer from temperature fluctuations due to silicon's high thermo-optic coefficient and therefore, temperature control in many applications is required. Here we present an athermal optical add-drop multiplexer fabricated from ring resonators. We used a sol-gel inorganic-organic hybrid material as an alternative to previously used materials such as polymers and titanium dioxide. In this work we studied the thermal curing parameters of the sol-gel and their effect on thermal wavelength shift of the rings. With this method, we were able to demonstrate a thermal shift down to -6.8 pm/°C for transverse electric (TE) polarization in ring resonators with waveguide widths of 325 nm when the sol-gel was cured at 130°C for 10.5 hours. We also achieved thermal shifts below 1 pm/°C for transverse magnetic (TM) polarization in the C band under different curing conditions. Curing time compared to curing temperature shows to be the most important factor to control sol-gel's thermo-optic value in order to obtain an athermal device in a wide temperature range.

Irrigation and Maize Cultivation Erode Plant Diversity Within Crops in Mediterranean Dry Cereal Agro-Ecosystems.

PubMed

Fagúndez, Jaime; Olea, Pedro P; Tejedo, Pablo; Mateo-Tomás, Patricia; Gómez, David

2016-07-01

The intensification of agriculture has increased production at the cost of environment and biodiversity worldwide. To increase crop yield in dry cereal systems, vast farmland areas of high conservation value are being converted into irrigation, especially in Mediterranean countries. We analyze the effect of irrigation-driven changes on the farm biota by comparing species diversity, community composition, and species traits of arable plants within crop fields from two contrasting farming systems (dry and irrigated) in Spain. We sampled plant species within 80 fields of dry wheat, irrigated wheat, and maize (only cultivated under irrigation). Wheat crops held higher landscape and per field species richness, and beta diversity than maize. Within the same type of crop, irrigated wheat hosted lower plant diversity than dry wheat at both field and landscape scales. Floristic composition differed between crop types, with higher frequencies of perennials, cosmopolitan, exotic, wind-pollinated and C4 species in maize. Our results suggest that irrigation projects, that transform large areas of dry cereal agro-ecosystems into irrigated crop systems dominated by maize, erode plant diversity. An adequate planning on the type and proportion of crops used in the irrigated agro-ecosystems is needed in order to balance agriculture production and biodiversity conservation.

Improved power steering with double and triple ring waveguide systems: the impact of the operating frequency.

PubMed

Kok, H P; de Greef, M; Borsboom, P P; Bel, A; Crezee, J

2011-01-01

Regional hyperthermia systems with 3D power steering have been introduced to improve tumour temperatures. The 3D 70-MHz AMC-8 system has two rings of four waveguides. The aim of this study is to evaluate whether T(90) will improve by using a higher operating frequency and whether further improvement is possible by adding a third ring. Optimised specific absorption rate (SAR) distributions were evaluated for a centrally located target in tissue-equivalent phantoms, and temperature optimisation was performed for five cervical carcinoma patients with constraints to normal tissue temperatures. The resulting T(90) and the thermal iso-effect dose (i.e. the number of equivalent min at 43°C) were evaluated and compared to the 2D 70-MHz AMC-4 system with a single ring of four waveguides. FDTD simulations were performed at 2.5 × 2.5 × 5 mm(3) resolution. The applied frequencies were 70, 100, 120, 130, 140 and 150 MHz. Optimised SAR distributions in phantoms showed an optimal SAR distribution at 140 MHz. For the patient simulations, an optimal increase in T(90) was observed at 130 MHz. For a two-ring system at 70 MHz the gain in T(90) was about 0.5°C compared to the AMC-4 system, averaged over the five patients. At 130 MHz the average gain in T(90) was ~1.5°C and ~2°C for a two and three-ring system, respectively. This implies an improvement of the thermal iso-effect dose with a factor ~12 and ~30, respectively. Simulations showed that a 130-MHz two-ring waveguide system yields significantly higher tumour temperatures compared to 70-MHz single-ring and double-ring waveguide systems. Temperatures were further improved with a 130-MHz triple-ring system.

Clinical features and course of refractory anemia with ring sideroblasts associated with marked thrombocytosis

PubMed Central

Broseus, Julien; Florensa, Lourdes; Zipperer, Esther; Schnittger, Susanne; Malcovati, Luca; Richebourg, Steven; Lippert, Eric; Cermak, Jaroslav; Evans, Jyoti; Mounier, Morgane; Raya, José Maria; Bailly, François; Gattermann, Norbert; Haferlach, Torsten; Garand, Richard; Allou, Kaoutar; Besses, Carlos; Germing, Ulrich; Haferlach, Claudia; Travaglino, Erica; Luno, Elisa; Pinan, Maria Angeles; Arenillas, Leonor; Rozman, Maria; Perez Sirvent, Maria Luz; Favre, Bernardine; Guy, Julien; Alonso, Esther; Ahwij, Nuhri; Jerez, Andrés; Hermouet, Sylvie; Maynadié, Marc; Cazzola, Mario; Girodon, François

2012-01-01

Background Refractory anemia with ring sideroblasts associated with marked thrombocytosis was proposed as a provisional entity in the 2001 World Health Organization classification of myeloid neoplasms and also in the 2008 version, but its existence as a single entity is contested. We wish to define the clinical features of this rare myelodysplastic/myeloproliferative neoplasm and to compare its clinical outcome with that of refractory anemia with ring sideroblasts and essential thrombocythemia. Design and Methods We conducted a collaborative retrospective study across Europe. Our database included 200 patients diagnosed with refractory anemia with ring sideroblasts and marked thrombocytosis. For each of these patients, each patient diagnosed with refractory anemia with ring sideroblasts was matched for age and sex. At the same time, a cohort of 454 patients with essential thrombocythemia was used to compare outcomes of the two diseases. Results In patients with refractory anemia with ring sideroblasts and marked thrombocytosis, depending on the Janus Kinase 2 V617F mutational status (positive or negative) or platelet threshold (over or below 600×109/L), no difference in survival was noted. However, these patients had shorter overall survival and leukemia-free survival with a lower risk of thrombotic complications than did patients with essential thrombocythemia (P<0.001) but better survival (P<0.001) and a higher risk of thrombosis (P=0.039) than patients with refractory anemia with ring sideroblasts. Conclusions The clinical course of refractory anemia with ring sideroblasts and marked thrombocytosis is better than that of refractory anemia with ring sideroblasts and worse than that of essential thrombocythemia. The higher risk of thrombotic events in this disorder suggests that anti-platelet therapy might be considered in this subset of patients. From a clinical point of view, it appears to be important to consider refractory anemia with ring sideroblasts and marked thrombocytosis as a distinct entity. PMID:22532522

Inference of higher-order relationships in the cycads from a large chloroplast data set.

PubMed

Rai, Hardeep S; O'Brien, Heath E; Reeves, Patrick A; Olmstead, Richard G; Graham, Sean W

2003-11-01

We investigated higher-order relationships in the cycads, an ancient group of seed-bearing plants, by examining a large portion of the chloroplast genome from seven species chosen to exemplify our current understanding of taxonomic diversity in the order. The regions considered span approximately 13.5 kb of unaligned data per taxon, and comprise a diverse range of coding sequences, introns and intergenic spacers dispersed throughout the plastid genome. Our results provide substantial support for most of the inferred backbone of cycad phylogeny, and weak evidence that the sister-group of the cycads among living seed plants is Ginkgo biloba. Cycas (representing Cycadaceae) is the sister-group of the remaining cycads; Dioon is part of the next most basal split. Two of the three commonly recognized families of cycads (Zamiaceae and Stangeriaceae) are not monophyletic; Stangeria is embedded within Zamiaceae, close to Zamia and Ceratozamia, and not closely allied to the other genus of Stangeriaceae, Bowenia. In contrast to the other seed plants, cycad chloroplast genomes share two features with Ginkgo: a reduced rate of evolution and an elevated transition:transversion ratio. We demonstrate that the latter aspect of their molecular evolution is unlikely to have affected inference of cycad relationships in the context of seed-plant wide analyses.

Invited review article: Large ring lasers for rotation sensing.

PubMed

Schreiber, Karl Ulrich; Wells, Jon-Paul R

2013-04-01

Over the last two decades a series of large ring laser gyroscopes have been built having an unparalleled scale factor. These upscaled devices have improved the sensitivity and stability for rotation rate measurements by six orders of magnitude when compared to previous commercial developments. This progress has made possible entirely new applications of ring laser gyroscopes in the fields of geophysics, geodesy, and seismology. Ring lasers are currently the only viable measurement technology, which is directly referenced to the instantaneous rotation axis of the Earth. The sensor technology is rapidly developing. This is evidenced by the first experimentally viable proposals to make terrestrial tests of general relativistic effects such as the frame dragging of the rotating Earth.

The occultation of 28 Sgr by Saturn - Saturn pole position and astrometry

NASA Technical Reports Server (NTRS)

Hubbard, W. B.; Porco, C. C.; Hunten, D. M.; Rieke, G. H.; Rieke, M. J.; Mccarthy, D. W.; Haemmerle, V.; Clark, R.; Turtle, E. P.; Haller, J.

1993-01-01

Saturn's ring plane-defined pole position is presently derived from the geometry of Saturn's July 3, 1989 occultation of 28 Sgr, as indicated by the timings of 12 circular edges in the Saturn C-ring as well as the edges of the Encke gap and the outer edge of the Keeler gap. The edge timings are used to solve for the position angle and opening angle of the apparent ring ellipses; the internal consistency of the data set and the redundancy of stations indicates an absolute error of the order of 5 km. The pole position thus obtained is consistent with the pole and ring radius scale derived from Voyager occultation observations.

Geometric and potential dynamics interpretation of the optic ring resonator bistability

NASA Astrophysics Data System (ADS)

Chiangga, S.; Chittha, T.; Frank, T. D.

2015-07-01

The optical bistability is a fundamental nonlinear feature of the ring resonator. A geometric and potential dynamics interpretation of the bistability is given. Accordingly, the bistability of the nonlinear system is shown to be a consequence of geometric laws of vector calculus describing the resonator ring. In contrast, the so-called transcendental relations that have been obtained in the literature in order to describe the optical wave are interpreted in terms of potential dynamical systems. The proposed novel interpretation provides new insights into the nature of the ring resonator optical bistability. The fundamental work by Rukhlenko, Premaratne and Agrawal (2010) as well as a more recent study by Chiangga, Pitakwongsaporn, Frank and Yupapin (2013) are considered.

Comparison of cycle control with a combined contraceptive vaginal ring and oral levonorgestrel/ethinyl estradiol.

PubMed

Bjarnadóttir, Ragnheidur I; Tuppurainen, Marjo; Killick, Stephen R

2002-03-01

The purpose of this study was to compare cycle control and tolerability of the NuvaRing (NV Organon, Oss, The Netherlands), a novel combined contraceptive vaginal ring, with a standard combined oral contraceptive pill. Healthy women aged 18 to 40 years who requested contraception received either NuvaRing or a combined oral contraceptive containing 30 microg ethinyl estradiol and 150 microg levonorgestrel for 6 cycles in 3 similarly designed studies. Each cycle comprised 3 weeks of ring or pill use, followed by 1 ring- or pill-free week. Two hundred forty-seven women began the studies, 121 women with NuvaRing and 126 women with the combined oral contraceptive. Withdrawal bleeding occurred in virtually all cycles in both groups. In the NuvaRing groups, the incidence of irregular bleeding was < or =5% in all cycles; this was lower than the combined oral contraceptive groups (5.4%-38.8%). Furthermore, the incidence of a normal intended bleeding pattern was significantly higher in the NuvaRing groups than in the combined oral contraceptive groups (P <.01). Both contraceptives were well tolerated. NuvaRing has excellent cycle control and is well tolerated.

Intravaginal ring delivery of the reverse transcriptase inhibitor TMC 120 as an HIV microbicide.

PubMed

Woolfson, A David; Malcolm, R Karl; Morrow, Ryan J; Toner, Clare F; McCullagh, Stephen D

2006-11-15

TMC 120 (Dapivirine) is a potent non-nucleoside reverse transcriptase inhibitor that is presently being developed as a vaginal HIV microbicide. To date, most vaginal microbicides under clinical investigation have been formulated as single-dose semi-solid gels, designed for application to the vagina before each act of intercourse. However, a clear rationale exists for providing long-term, controlled release of vaginal microbicides in order to afford continuous protection against heterosexually transmitted HIV infection and to improve user compliance. In this study we report on the incorporation of various pharmaceutical excipients into TMC 120 silicone, reservoir-type intravaginal rings (IVRs) in order to modify the controlled release characteristics of the microbicide. The results demonstrate that TMC 120 is released in zero-order fashion from the rings over a 28-day period and that release parameters could be modified by the inclusion of release-modifying excipients in the IVR. The hydrophobic liquid excipient isopropyl myristate had little effect on steady-state daily release rates, but did increase the magnitude and duration of burst release in proportion to excipient loading in the IVR. By comparison, the hydrophobic liquid poly(dimethylsiloxane) had little effect on TMC 120 release parameters. A hydrophilic excipient, lactose, had the surprising effect of decreasing TMC 120 burst release while increasing the apparent steady-state daily release in a concentration-dependent manner. Based on previous cell culture data and vaginal physiology, TMC120 is released from the various ring formulations in amounts potentially capable of maintaining a protective vaginal concentration. It is further predicted that the observed release rates may be maintained for at least a period of 1 year from a single ring device. TMC 120 release profiles and the mechanical properties of rings could be modified by the physicochemical nature of hydrophobic and hydrophilic excipients incorporated into the IVRs.

Pharmacological study of the mechanisms involved in the vasodilator effect produced by the acute application of triiodothyronine to rat aortic rings

PubMed Central

Lozano-Cuenca, J.; López-Canales, O.A.; Aguilar-Carrasco, J.C.; Villagrana-Zesati, J.R.; López-Mayorga, R.M.; Castillo-Henkel, E.F.; López-Canales, J.S.

2016-01-01

A relationship between thyroid hormones and the cardiovascular system has been well established in the literature. The present in vitro study aimed to investigate the mechanisms involved in the vasodilator effect produced by the acute application of 10-8–10-4 M triiodothyronine (T3) to isolated rat aortic rings. Thoracic aortic rings from 80 adult male Wistar rats were isolated and mounted in tissue chambers filled with Krebs-Henseleit bicarbonate buffer in order to analyze the influence of endothelial tissue, inhibitors and blockers on the vascular effect produced by T3. T3 induced a vasorelaxant response in phenylephrine-precontracted rat aortic rings at higher concentrations (10-4.5–10-4.0 M). This outcome was unaffected by 3.1×10-7 M glibenclamide, 10-3 M 4-aminopyridine (4-AP), 10-5 M indomethacin, or 10-5 M cycloheximide. Contrarily, vasorelaxant responses to T3 were significantly (P<0.05) attenuated by endothelium removal or the application of 10-6 M atropine, 10-5 M L-NG-nitroarginine methyl ester (L-NAME), 10-7 M 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), 10-6 M (9S,10R,12R)-2,3,9,10,11,12-Hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3′,2′,1′-kl]pyrrolo[3,4-i](1,6)benzodiazocine-10-carboxylic acid, methyl ester KT 5823, 10-2 M tetraethylammonium (TEA), or 10-7 M apamin plus 10-7 M charybdotoxin. The results suggest the involvement of endothelial mechanisms in the vasodilator effect produced by the acute in vitro application of T3 to rat aortic rings. Possible mechanisms include the stimulation of muscarinic receptors, activation of the NO-cGMP-PKG pathway, and opening of Ca2+-activated K+ channels. PMID:27464023

Binding of Alkali Metal Ions with 1,3,5-Tri(phenyl)benzene and 1,3,5-Tri(naphthyl)benzene: The Effect of Phenyl and Naphthyl Ring Substitution on Cation-π Interactions Revealed by DFT Study.

PubMed

Mirchi, Ali; Sizochenko, Natalia; Dinadayalane, Tandabany; Leszczynski, Jerzy

2017-11-22

The effect of substitution of phenyl and naphthyl rings to benzene was examined to elucidate the cation-π interactions involving alkali metal ions with 1,3,5-tri(phenyl)benzene (TPB) and 1,3,5-tri(naphthyl)benzene (TNB). Benzene, TPB, and four TNB isomers (with ααα, ααβ, αββ, and βββ types of fusion) and their complexes with Li + , Na + , K + , Rb + , and Cs + were optimized using DFT approach with B3LYP and M06-2X functionals in conjunction with the def2-QZVP basis set. Higher relative stability of β,β,β-TNB over α,α,α-TNB can be attributed to peri repulsion, which is defined as the nonbonding repulsive interaction between substituents in the 1- and the 8-positions on the naphthalene core. Binding energies, distances between ring centroid and the metal ions, and the distance to metal ions from the center of other six-membered rings were compared for all complexes. Our computational study reveals that the binding affinity of alkali metal cations increases significantly with the 1,3,5-trisubstitution of phenyl and naphthyl rings to benzene. The detailed computational analyses of geometries, partial charges, binding energies, and ligand organization energies reveal the possibility of favorable C-H···M + interactions when a α-naphthyl group exists in complexes of TNB structures. Like benzene-alkali metal ion complexes, the binding affinity of metal ions follows the order: Li + > Na + > K + > Rb + > Cs + for any considered 1,3,5-trisubstituted benzene systems. In case of TNB, we found that the strength of interactions increases as the fusion point changes from α to β position of naphthalene.

Near--Infrared Imaging of the Starburst Ring in UGC12815

NASA Astrophysics Data System (ADS)

Smith, D. A.; Herter, T.; Haynes, M. P.; Neff, S. G.

1995-05-01

Starburst galaxies define an enigmatic class of objects undergoing a brief, intense episode of star formation. In order to investigate the nature of nearby starbursts, we have analyzed the 20 starburst galaxies with the highest 4.85 GHz luminosities from the survey of Condon, Frayer, & Broderick (1991, AJ, 101, 362) at infrared and optical wavelengths. As part of our study, we recently used the Cassegrain Infrared Camera at the Hale 5 m telescope to obtain high spatial resolution near--infrared images of the cores of 17 of these galaxies in order to better understand the starburst triggering mechanism. We find that one galaxy, UGC12815 (NGC7771), possesses a nucleus surrounded by a bright starburst ring. We present 1.25, 1.65, and 2.2 microns (J, H, and K band) images of the nuclear region of UGC12815 and a preliminary analysis of the properties of the starburst ring. The resolution of our K band image is 0.6('') FWHM. The ring is ~ 1.6 kpc (6('') ) in diameter assuming H_0=75 km/s/Mpc; several knots are detected in the ring at 2.2 microns. The spatial distribution of these knots is compared to that observed at 6 cm. The luminosities of the ring and nucleus, as mapped in the near--infrared and radio, are also discussed. Color maps (H-K and J-H) constructed from the near--infrared images trace the relative roles of extinction, and emission from evolved red stars, blue stars, thermal gas, and hot dust in the nucleus and starburst ring. A comparison between UGC12815 and other systems with circumnuclear starbursts is also made.

Beam Loss Measurements at the Los Alamos Proton Storage Ring

NASA Astrophysics Data System (ADS)

Spickermann, Thomas

2005-06-01

During normal operation the Los Alamos Proton Storage Ring (PSR) accumulates up to 4ṡ1013 protons over 625μs with a repetition rate of 20 Hz, corresponding to a current of 125μA to the Lujan Neutron Science Center. Beam losses in the ring as well as in the extraction beam line and the subsequent activation of material are a limiting factor at these currents. Careful tuning of injection, ring and extraction line is paramount to limiting losses to acceptable levels. Losses are typically not uniform around the ring, but occur in significantly higher levels in certain "hot spots". Here I will report on losses related to the stripper foil which are the dominant source of losses in the ring. First results of a comparison with simulations will also be presented.

Quinoxaline-substituted chalcones as new inhibitors of breast cancer resistance protein ABCG2: polyspecificity at B-ring position

PubMed Central

Winter, Evelyn; Gozzi, Gustavo Jabor; Chiaradia-Delatorre, Louise Domeneghini; Daflon-Yunes, Nathalia; Terreux, Raphael; Gauthier, Charlotte; Mascarello, Alessandra; Leal, Paulo César; Cadena, Silvia M; Yunes, Rosendo Augusto; Nunes, Ricardo José; Creczynski-Pasa, Tania Beatriz; Di Pietro, Attilio

2014-01-01

A series of chalcones substituted by a quinoxaline unit at the B-ring were synthesized and tested as inhibitors of breast cancer resistance protein-mediated mitoxantrone efflux. These compounds appeared more efficient than analogs containing other B-ring substituents such as 2-naphthyl or 3,4-methylenedioxyphenyl while an intermediate inhibitory activity was obtained with a 1-naphthyl group. In all cases, two or three methoxy groups had to be present on the phenyl A-ring to produce a maximal inhibition. Molecular modeling indicated both electrostatic and steric positive contributions. A higher potency was observed when the 2-naphthyl or 3,4-methylenedioxyphenyl group was shifted to the A-ring and methoxy substituents were shifted to the phenyl B-ring, indicating preferences among polyspecificity of inhibition. PMID:24920885

Synthesis, reactivity and application studies for different biolubricants

PubMed Central

2014-01-01

Vegetable oils have different unique properties owing to their unique chemical structure. Vegetable oils have a greater ability to lubricate and have higher viscosity indices. Therefore, they are being more closely examined as base oil for biolubricants and functional fluids. In spite of their many advantages, vegetable oils suffer from two major drawbacks of inadequate oxidative stability and poor low-temperature properties, which hinder their utilization as biolubricant base oils. Transforming alkene groups in fatty acids to other stable functional groups could improve the oxidative stability, whereas reducing structural uniformity of the oil by attaching alkyl side chains could improve the low-temperature performance. In that light, the epoxidation of unsaturated fatty acids is very interesting as it can provide diverse side chains arising from the mono- or di-epoxidation of the unsaturated fatty acid. Oxirane ring opening by an acid-catalyzed reaction with a suitable reagent provides interesting polyfunctional compounds. PMID:24612780

Increased egg estradiol concentration feminizes digit ratios of male pheasants (Phasianus colchicus)

NASA Astrophysics Data System (ADS)

Saino, N.; Rubolini, D.; Romano, M.; Boncoraglio, G.

2007-03-01

The length ratio between individual digits differs between males and females in humans, other mammals, lizards, and one bird species. Sexual dimorphism in digit ratios and variation among individuals of the same sex may depend on differential exposure to androgens and estrogens during embryonic life. Organizational effects of sex hormones could cause the observed correlations between digit ratios and diverse phenotypic traits in humans. However, no study has investigated experimentally the effect of prenatal estrogens on digit ratios. We analyzed the effect of estradiol injection in ring-necked pheasant (Phasianus colchicus) eggs on digit ratios. Males from control eggs had higher ratios between the second or third and the fourth digit of the right foot compared to females. Estradiol-treated eggs produced males with lower (feminized) right foot second to fourth digit ratio. Thus, we provided the first experimental evidence that prenatal exposure to physiologically high estrogen levels affects bird digit ratios.

In situ measurements of Saturn's ionosphere show that it is dynamic and interacts with the rings.

PubMed

Wahlund, J-E; Morooka, M W; Hadid, L Z; Persoon, A M; Farrell, W M; Gurnett, D A; Hospodarsky, G; Kurth, W S; Ye, S-Y; Andrews, D J; Edberg, N J T; Eriksson, A I; Vigren, E

2018-01-05

The ionized upper layer of Saturn's atmosphere, its ionosphere, provides a closure of currents mediated by the magnetic field to other electrically charged regions (for example, rings) and hosts ion-molecule chemistry. In 2017, the Cassini spacecraft passed inside the planet's rings, allowing in situ measurements of the ionosphere. The Radio and Plasma Wave Science instrument detected a cold, dense, and dynamic ionosphere at Saturn that interacts with the rings. Plasma densities reached up to 1000 cubic centimeters, and electron temperatures were below 1160 kelvin near closest approach. The density varied between orbits by up to two orders of magnitude. Saturn's A- and B-rings cast a shadow on the planet that reduced ionization in the upper atmosphere, causing a north-south asymmetry. Copyright © 2018, American Association for the Advancement of Science.

Phylogenetically and Spatially Close Marine Sponges Harbour Divergent Bacterial Communities

PubMed Central

Hardoim, Cristiane C. P.; Esteves, Ana I. S.; Pires, Francisco R.; Gonçalves, Jorge M. S.; Cox, Cymon J.; Xavier, Joana R.; Costa, Rodrigo

2012-01-01

Recent studies have unravelled the diversity of sponge-associated bacteria that may play essential roles in sponge health and metabolism. Nevertheless, our understanding of this microbiota remains limited to a few host species found in restricted geographical localities, and the extent to which the sponge host determines the composition of its own microbiome remains a matter of debate. We address bacterial abundance and diversity of two temperate marine sponges belonging to the Irciniidae family - Sarcotragus spinosulus and Ircinia variabilis – in the Northeast Atlantic. Epifluorescence microscopy revealed that S. spinosulus hosted significantly more prokaryotic cells than I. variabilis and that prokaryotic abundance in both species was about 4 orders of magnitude higher than in seawater. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) profiles of S. spinosulus and I. variabilis differed markedly from each other – with higher number of ribotypes observed in S. spinosulus – and from those of seawater. Four PCR-DGGE bands, two specific to S. spinosulus, one specific to I. variabilis, and one present in both sponge species, affiliated with an uncultured sponge-specific phylogenetic cluster in the order Acidimicrobiales (Actinobacteria). Two PCR-DGGE bands present exclusively in S. spinosulus fingerprints affiliated with one sponge-specific phylogenetic cluster in the phylum Chloroflexi and with sponge-derived sequences in the order Chromatiales (Gammaproteobacteria), respectively. One Alphaproteobacteria band specific to S. spinosulus was placed in an uncultured sponge-specific phylogenetic cluster with a close relationship to the genus Rhodovulum. Our results confirm the hypothesized host-specific composition of bacterial communities between phylogenetically and spatially close sponge species in the Irciniidae family, with S. spinosulus displaying higher bacterial community diversity and distinctiveness than I. variabilis. These findings suggest a pivotal host-driven effect on the shape of the marine sponge microbiome, bearing implications to our current understanding of the distribution of microbial genetic resources in the marine realm. PMID:23300853

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

Paranin, V. D.

In work we investigated yttrium iron garnet epitaxial films with a thickness of 10 µm and 55 µm which were grown on the surface of garnet substrate. Using the polarizing microscopy method the branching domain structure of films was shown with the period of domains 21.5 µm and 42.5 µm. Disappearance of domains at presence of an external magnetic field up to 100 Oe was noted. The optical transmission of films for the polarized beam of HeNe laser is investigated and zero diffraction order and odd diffraction rings orders were shown. Interconnection of the period of chaotically oriented domains with angles of axially symmetricmore » diffraction rings orders was shown. Diffraction patterns at various longitudinal magnetic fields are investigated. Disappearance of odd diffraction orders and increasing in intensity of zero diffraction order were fixed. Optical transmission of epitaxial films was measured in range of 500 - 900 nm.« less

Evidence of van Hove singularities in ordered grain boundaries of graphene.

PubMed

Ma, Chuanxu; Sun, Haifeng; Zhao, Yeliang; Li, Bin; Li, Qunxiang; Zhao, Aidi; Wang, Xiaoping; Luo, Yi; Yang, Jinlong; Wang, Bing; Hou, J G

2014-06-06

It has long been under debate whether the electron transport performance of graphene could be enhanced by the possible occurrence of van Hove singularities in grain boundaries. Here, we provide direct experimental evidence to confirm the existence of van Hove singularity states close to the Fermi energy in certain ordered grain boundaries using scanning tunneling microscopy. The intrinsic atomic and electronic structures of two ordered grain boundaries, one with alternative pentagon and heptagon rings and the other with alternative pentagon pair and octagon rings, are determined. It is firmly verified that the carrier concentration and, thus, the conductance around ordered grain boundaries can be significantly enhanced by the van Hove singularity states. This finding strongly suggests that a graphene nanoribbon with a properly embedded ordered grain boundary can be a promising structure to improve the performance of graphene-based electronic devices.

Structuring of Bacterioplankton Diversity in a Large Tropical Bay

PubMed Central

Gregoracci, Gustavo B.; Nascimento, Juliana R.; Cabral, Anderson S.; Paranhos, Rodolfo; Valentin, Jean L.; Thompson, Cristiane C.; Thompson, Fabiano L.

2012-01-01

Structuring of bacterioplanktonic populations and factors that determine the structuring of specific niche partitions have been demonstrated only for a limited number of colder water environments. In order to better understand the physical chemical and biological parameters that may influence bacterioplankton diversity and abundance, we examined their productivity, abundance and diversity in the second largest Brazilian tropical bay (Guanabara Bay, GB), as well as seawater physical chemical and biological parameters of GB. The inner bay location with higher nutrient input favored higher microbial (including vibrio) growth. Metagenomic analysis revealed a predominance of Gammaproteobacteria in this location, while GB locations with lower nutrient concentration favored Alphaproteobacteria and Flavobacteria. According to the subsystems (SEED) functional analysis, GB has a distinctive metabolic signature, comprising a higher number of sequences in the metabolism of phosphorus and aromatic compounds and a lower number of sequences in the photosynthesis subsystem. The apparent phosphorus limitation appears to influence the GB metagenomic signature of the three locations. Phosphorus is also one of the main factors determining changes in the abundance of planktonic vibrios, suggesting that nutrient limitation can be observed at community (metagenomic) and population levels (total prokaryote and vibrio counts). PMID:22363639

Stress analysis in oral obturator prostheses, part II: photoelastic imaging

NASA Astrophysics Data System (ADS)

Pesqueira, Aldiéris Alves; Goiato, Marcelo Coelho; da Silva, Emily Vivianne Freitas; Haddad, Marcela Filié; Moreno, Amália; Zahoui, Abbas; dos Santos, Daniela Micheline

2014-06-01

In part I of the study, two attachment systems [O-ring; bar-clip (BC)] were used, and the system with three individualized O-rings provided the lowest stress on the implants and the support tissues. Therefore, the aim of this study was to assess the stress distribution, through the photoelastic method, on implant-retained palatal obturator prostheses associated with different attachment systems: BOC-splinted implants with a bar connected to two centrally placed O-rings, and BOD-splinted implants with a BC connected to two distally placed O-rings (cantilever). One photoelastic model of the maxilla with oral-sinus-nasal communication with three parallel implants was fabricated. Afterward, two implant-retained palatal obturator prostheses with the two attachment systems described above were constructed. Each assembly was positioned in a circular polariscope and a 100-N axial load was applied in three different regions with implants by using a universal testing machine. The results were obtained through photograph record analysis of stress. The BOD system exhibited the highest stress concentration, followed by the BOC system. The O-ring, centrally placed on the bar, allows higher mobility of the prostheses and homogeneously distributes the stress to the region of the alveolar ridge and implants. It can be concluded that the use of implants with O-rings, isolated or connected with a bar, to rehabilitate maxillectomized patients allows higher prosthesis mobility and homogeneously distributes the stress to the alveolar ridge region, which may result in greater chewing stress distribution to implants and bone tissue. The clinical implication of the augmented bone support loss after maxillectomy is the increase of stress in the attachment systems and, consequently, a higher tendency for displacement of the prosthesis.

Near-threshold photoionization of hydrogenlike uranium studied in ion-atom collisions via the time-reversed process.

PubMed

Stöhlker, T; Ma, X; Ludziejewski, T; Beyer, H F; Bosch, F; Brinzanescu, O; Dunford, R W; Eichler, J; Hagmann, S; Ichihara, A; Kozhuharov, C; Krämer, A; Liesen, D; Mokler, P H; Stachura, Z; Swiat, P; Warczak, A

2001-02-05

Radiative electron capture, the time-reversed photoionization process occurring in ion-atom collisions, provides presently the only access to photoionization studies for very highly charged ions. By applying the deceleration mode of the ESR storage ring, we studied this process in low-energy collisions of bare uranium ions with low- Z target atoms. This technique allows us to extend the current information about photoionization to much lower energies than those accessible for neutral heavy elements in the direct reaction channel. The results prove that for high- Z systems, higher-order multipole contributions and magnetic corrections persist even at energies close to the threshold.

Nonlinear Binormal Flow of Vortex Filaments

NASA Astrophysics Data System (ADS)

Strong, Scott; Carr, Lincoln

2015-11-01

With the current advances in vortex imaging of Bose-Einstein condensates occurring at the Universities of Arizona, São Paulo and Cambridge, interest in vortex filament dynamics is experiencing a resurgence. Recent simulations, Salman (2013), depict dissipative mechanisms resulting from vortex ring emissions and Kelvin wave generation associated with vortex self-intersections. As the local induction approximation fails to capture reconnection events, it lacks a similar dissipative mechanism. On the other hand, Strong&Carr (2012) showed that the exact representation of the velocity field induced by a curved segment of vortex contains higher-order corrections expressed in powers of curvature. This nonlinear binormal flow can be transformed, Hasimoto (1972), into a fully nonlinear equation of Schrödinger type. Continued transformation, Madelung (1926), reveals that the filament's square curvature obeys a quasilinear scalar conservation law with source term. This implies a broader range of filament dynamics than is possible with the integrable linear binormal flow. In this talk we show the affect higher-order corrections have on filament dynamics and discuss physical scales for which they may be witnessed in future experiments. Partially supported by NSF.

Forging the ring: from fungal septins' divergent roles in morphology, septation and virulence to factors contributing to their assembly into higher order structures.

PubMed

Vargas-Muñiz, Jose M; Juvvadi, Praveen R; Steinbach, William J

2016-09-01

Septins are a conserved family of GTP-binding proteins that are distributed across different lineages of the eukaryotes, with the exception of plants. Septins perform a myriad of functions in fungal cells, ranging from controlling morphogenetic events to contributing to host tissue invasion and virulence. One key attribute of the septins is their ability to assemble into heterooligomeric complexes that organizse into higher order structures. In addition to the established role of septins in the model budding yeast, Saccharomyces cerevisiae, their importance in other fungi recently emerges. While newer roles for septins are being uncovered in these fungi, the mechanism of how septins assemble into a complex and their regulation is only beginning to be comprehended. In this review, we summarize recent findings on the role of septins in different fungi and focus on how the septin complexes of different fungi are organized in vitro and in vivo. Furthermore, we discuss on how phosphorylation/dephosphorylation can serve as an important mechanism of septin complex assembly and regulation.

High resolution monochromator for the VUV radiation from the DORIS storage ring

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

Saile, V.; Gurtler, P.; Koch, E.E.

1976-10-01

The unique properties of the DORIS storage ring at DESY as a synchroton radiation source are exploited for high resolution spectroscopy in the vacuum ultraviolet. We describe a new experimental set up with a 3-m normal incidence monochromator for wavelengths between 3000 A and 300 A (4 < or = h..omega.. < or = 40 eV) using a vertical dispersion plane. The storage ring provides a light flux intense and stable enough for rapid photoelectrical scanning of the spectra with a resolution of 0.03 A in first order. (AIP)

Design Study of an MBA Lattice for the Advanced Photon Source

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

Decker, Glenn

2014-11-02

Recent interest in ultra-low-emittance designs for storage-ring-based synchrotron light sources has spurred a focused design effort on a multi-bend achromat (MBA) storage ring replacement for the Advanced Photon Source (APS). The APS is relatively large (1104 m circumference) and, as such, an upgrade to a fourth-generation storage ring holds the potential for a two to three order of magnitude enhancement of X-ray brightness due to the approximate inverse cubic scaling of emittance with the number of dipole bend magnets.

Four diterpenoid inhibitors of Cdc25B phosphatase from a marine anemone.

PubMed

Cao, Shugeng; Foster, Caleb; Lazo, John S; Kingston, David G I

2005-10-15

Three new diterpenoids and one known diterpenoid have been isolated from a sea anemone of the order Actiniara, and the structures of the new compounds, actiniarins A-C (1-3) were established on the basis of extensive 1D and 2D NMR spectroscopic data interpretation. Compound 1 has a six-membered ring hemiacetal ring, and the equilibrium of this ring is discussed. All the isolates were evaluated for their inhibition of Cdc25B and for cytotoxicity against the A2780 ovarian cancer cell line.

Little-Parks oscillations in superconducting ring with Josephson junctions

NASA Astrophysics Data System (ADS)

Sharon, Omri J.; Sharoni, Amos; Berger, Jorge; Shaulov, Avner; Yeshurun, Yosi

2018-03-01

Nb nano-rings connected serially by Nb wires exhibit, at low bias currents, the typical parabolic Little-Parks magnetoresistance oscillations. As the bias current increases, these oscillations become sinusoidal. This result is ascribed to the generation of Josephson junctions caused by the combined effect of current-induced phase slips and the non-uniformity of the order parameter along each ring due to the Nb wires attached to it. This interpretation is validated by further increasing the bias current, which results in magnetoresistance oscillations typical of a SQUID.

Ring Current Response to Different Storm Drivers. Van Allen Probes and Cluster Observations.

NASA Astrophysics Data System (ADS)

Bingham, S.; Mouikis, C.; Kistler, L. M.; Spence, H. E.; Gkioulidou, M.; Claudepierre, S. G.; Farrugia, C. J.

2015-12-01

The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), co-rotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure change the global magnetic field, which affects the transport of the radiation belts. In order to determine the field changes during a storm it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. The source population of the storm time ring current is the night side plasma sheet. However, it is not clear how these convecting particles affect the storm time ring current pressure development. We use Van Allen Probes and Cluster observations together with the Volland-Stern and dipole magnetic field models to determine the contribution in the ring current pressure of the plasma sheet particles convecting from the night side that are on open drift paths, during the storm evolution. We compare storms that are related to different interplanetary drivers, CME and CIR, as observed at different local times.

Optimal design and fabrication of ring resonator composed of Ge02-doped silica waveguides for IOG

NASA Astrophysics Data System (ADS)

Guo, Lijun; Shi, Bangren; Chen, Chen; Lv, Hao; Zhao, Zhenming; Zhao, Meng

2009-07-01

The ring resonator is the core sensing element in the resonant integration optical gyroscope (IOG) . Its performances influence the minimum resolution and the error items of gyroscope directly and it is the key of the design and manufacturing. This paper presents optimal design of ring resonator composed of Ge02 -doped silica waveguides fabricated on silicon substrates using wide angle beam propagation method (WA-BPM). The characteristic of the light propagating across the ring resonator is analyzed. According to the design results, we succeed in fabricating the ring resonator by Plasma Enhanced Chemical Vapor Deposition (PECVD) method and Reactive Ion Etching (RIE) technology. In order to characterize the ring resonator, an optical measurement setup is built, fiber laser line-width is 50 kHz, detector responsibility is 0.95A/W and integral time is 10s. By testing, propagation loss and total loss of ring resonator are 0.02dB/cm and 0.1dB/circuit respectively. Observed from the resonance curve, a finesse of 12.5.

Resonant circuit which provides dual-frequency excitation for rapid cycling of an electromagnet

DOEpatents

Praeg, W.F.

1982-03-09

Disclosed is a novel ring-magnet control circuit that permits synchrotron repetition rates much higher than the frequency of the sinusoidal guide field of the ring magnet during particle acceleration. The control circuit generates sinusoidal excitation currents of different frequencies in the half waves. During radio-frequency acceleration of the synchrotron, the control circuit operates with a lower frequency sine wave and, thereafter, the electromagnets are reset with a higher-frequency half sine wave.

Diversity and Biosynthetic Potential of Culturable Microbes Associated with Toxic Marine Animals

PubMed Central

Chau, Rocky; Kalaitzis, John A.; Wood, Susanna A.; Neilan, Brett A.

2013-01-01

Tetrodotoxin (TTX) is a neurotoxin that has been reported from taxonomically diverse organisms across 14 different phyla. The biogenic origin of tetrodotoxin is still disputed, however, TTX biosynthesis by host-associated bacteria has been reported. An investigation into the culturable microbial populations from the TTX-associated blue-ringed octopus Hapalochlaena sp. and sea slug Pleurobranchaea maculata revealed a surprisingly high microbial diversity. Although TTX was not detected among the cultured isolates, PCR screening identifiedsome natural product biosynthesis genes putatively involved in its assembly. This study is the first to report on the microbial diversity of culturable communities from H. maculosa and P. maculata and common natural product biosynthesis genes from their microbiota. We also reassess the production of TTX reported from three bacterial strains isolated from the TTX-containing gastropod Nassarius semiplicatus. PMID:23917066

Diversity and biosynthetic potential of culturable microbes associated with toxic marine animals.

PubMed

Chau, Rocky; Kalaitzis, John A; Wood, Susanna A; Neilan, Brett A

2013-08-02

Tetrodotoxin (TTX) is a neurotoxin that has been reported from taxonomically diverse organisms across 14 different phyla. The biogenic origin of tetrodotoxin is still disputed, however, TTX biosynthesis by host-associated bacteria has been reported. An investigation into the culturable microbial populations from the TTX-associated blue-ringed octopus Hapalochlaena sp. and sea slug Pleurobranchaea maculata revealed a surprisingly high microbial diversity. Although TTX was not detected among the cultured isolates, PCR screening identifiedsome natural product biosynthesis genes putatively involved in its assembly. This study is the first to report on the microbial diversity of culturable communities from H. maculosa and P. maculata and common natural product biosynthesis genes from their microbiota. We also reassess the production of TTX reported from three bacterial strains isolated from the TTX-containing gastropod Nassarius semiplicatus.

The Effect of n vs. iso Isomerization on the Thermophysical Properties of Aromatic and Non-aromatic Ionic Liquids.

PubMed

Rodrigues, Ana S M C; Almeida, Hugo F D; Freire, Mara G; Lopes-da-Silva, José A; Coutinho, João A P; Santos, Luís M N B F

2016-09-15

This work explores the n vs. iso isomerization effects on the physicochemical properties of different families of ionic liquids (ILs) with variable aromaticity and ring size. This study comprises the experimental measurements, in a wide temperature range, of the ILs' thermal behavior, heat capacities, densities, refractive indices, surface tensions, and viscosities. The results here reported show that the presence of the iso -alkyl group leads to an increase of the temperature of the glass transition, T g . The iso- pyrrolidinium (5 atoms ring cation core) and iso -piperidinium (6 atoms ring cation core) ILs present a strong differentiation in the enthalpy and entropy of melting. Non-aromatic ILs have higher molar heat capacities due to the increase of the atomic contribution, whereas it was not found any significant differentiation between the n and iso -alkyl isomers. A small increase of the surface tension was observed for the non-aromatic ILs, which could be related to their higher cohesive energy of the bulk, while the lower surface entropy observed for the iso isomers indicates a structural resemblance between the IL bulk and surface. The significant differentiation between ILs with a 5 and 6 atoms ring cation in the n -alkyl series (where 5 atoms ring cations have higher surface entropy) is an indication of a more efficient arrangement of the non-polar region at the surface in ILs with smaller cation cores. The ILs constituted by non-aromatic piperidinium cation, and iso -alkyl isomers were found to be the most viscous among the studied ILs due to their higher energy barriers for shear stress.

High energy efficient solid state laser sources

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1988-01-01

Recent progress in the development of highly efficient coherent optical sources is reviewed. This work focusses on nonlinear frequency conversion of the highly coherent output of the Non-Planar Ring Laser Oscillators developed earlier in the program, and includes high efficiency second harmonic generation and the operation of optical parametric oscillators for wavelength diversity and tunability.

Phenolics and compartmentalization in the sapwood of broad-leaved trees

Treesearch

Kevin T. Smith

1997-01-01

Tree survival depends on the chemistry of phenolic compounds, a broad class of chemicals characterized by a hydroxylated benzene ring. In trees, phenolics occur frequently as polymers, acids, or glycosylated esters and perform diverse functions. For example, lignin, a phenylpropane heteropolymer, provides structural strength to wood. The induced production of phenols...

Recent Progress on the Stereoselective Synthesis of Cyclic Quaternary α-Amino Acids

PubMed Central

Cativiela, Carlos; Ordóñez, Mario

2010-01-01

The most recent papers describing the stereoselective synthesis of cyclic quaternary α-amino acids are collected in this review. The diverse synthetic approaches are classified according to the size of the ring and taking into account the bond that is formed to complete the quaternary skeleton. PMID:20300486

Employing the promiscuity of lantibiotic biosynthetic machineries to produce novel antimicrobials.

PubMed

Montalbán-López, Manuel; van Heel, Auke J; Kuipers, Oscar P

2017-01-01

As the number of new antibiotics that reach the market is decreasing and the demand for them is rising, alternative sources of novel antimicrobials are needed. Lantibiotics are potent peptide antimicrobials that are ribosomally synthesized and stabilized by post-translationally introduced lanthionine rings. Their ribosomal synthesis and enzymatic modifications provide excellent opportunities to design and engineer a large variety of novel antimicrobial compounds. The research conducted in this area demonstrates that the modularity present in both the peptidic rings as well as in the combination of promiscuous modification enzymes can be exploited to further increase the diversity of lantibiotics. Various approaches, where the modifying enzymes and corresponding leader peptides are decoupled from their natural core peptide and integrated in designed plug-and-play production systems, enable the production of modified peptides that are either derived from vast genomic data or designed using functional parts from a wide diversity of core peptides. These approaches constitute a powerful discovery platform to develop novel antimicrobials with high therapeutic potential. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The tripartite motif coiled-coil is an elongated antiparallel hairpin dimer.

PubMed

Sanchez, Jacint G; Okreglicka, Katarzyna; Chandrasekaran, Viswanathan; Welker, Jordan M; Sundquist, Wesley I; Pornillos, Owen

2014-02-18

Tripartite motif (TRIM) proteins make up a large family of coiled-coil-containing RING E3 ligases that function in many cellular processes, particularly innate antiviral response pathways. Both dimerization and higher-order assembly are important elements of TRIM protein function, but the atomic details of TRIM tertiary and quaternary structure have not been fully understood. Here, we present crystallographic and biochemical analyses of the TRIM coiled-coil and show that TRIM proteins dimerize by forming interdigitating antiparallel helical hairpins that position the N-terminal catalytic RING domains at opposite ends of the dimer and the C-terminal substrate-binding domains at the center. The dimer core comprises an antiparallel coiled-coil with a distinctive, symmetric pattern of flanking heptad and central hendecad repeats that appear to be conserved across the entire TRIM family. Our studies reveal how the coiled-coil organizes TRIM25 to polyubiquitylate the RIG-I/viral RNA recognition complex and how dimers of the TRIM5α protein are arranged within hexagonal arrays that recognize the HIV-1 capsid lattice and restrict retroviral replication.

The tripartite motif coiled-coil is an elongated antiparallel hairpin dimer

PubMed Central

Sanchez, Jacint G.; Okreglicka, Katarzyna; Chandrasekaran, Viswanathan; Welker, Jordan M.; Sundquist, Wesley I.; Pornillos, Owen

2014-01-01

Tripartite motif (TRIM) proteins make up a large family of coiled-coil-containing RING E3 ligases that function in many cellular processes, particularly innate antiviral response pathways. Both dimerization and higher-order assembly are important elements of TRIM protein function, but the atomic details of TRIM tertiary and quaternary structure have not been fully understood. Here, we present crystallographic and biochemical analyses of the TRIM coiled-coil and show that TRIM proteins dimerize by forming interdigitating antiparallel helical hairpins that position the N-terminal catalytic RING domains at opposite ends of the dimer and the C-terminal substrate-binding domains at the center. The dimer core comprises an antiparallel coiled-coil with a distinctive, symmetric pattern of flanking heptad and central hendecad repeats that appear to be conserved across the entire TRIM family. Our studies reveal how the coiled-coil organizes TRIM25 to polyubiquitylate the RIG-I/viral RNA recognition complex and how dimers of the TRIM5α protein are arranged within hexagonal arrays that recognize the HIV-1 capsid lattice and restrict retroviral replication. PMID:24550273

Intermittent burst of a super rogue wave in the breathing multi-soliton regime of an anomalous fiber ring cavity.

PubMed

Lee, Seungjong; Park, Kyoungyoon; Kim, Hyuntai; Vazquez-Zuniga, Luis Alonso; Kim, Jinseob; Jeong, Yoonchan

2018-04-30

We report the intermittent burst of a super rogue wave in the multi-soliton (MS) regime of an anomalous-dispersion fiber ring cavity. We exploit the spatio-temporal measurement technique to log and capture the shot-to-shot wave dynamics of various pulse events in the cavity, and obtain the corresponding intensity probability density function, which eventually unveils the inherent nature of the extreme events encompassed therein. In the breathing MS regime, a specific MS regime with heavy soliton population, the natural probability of pulse interaction among solitons and dispersive waves exponentially increases owing to the extraordinarily high soliton population density. Combination of the probabilistically started soliton interactions and subsequently accompanying dispersive waves in their vicinity triggers an avalanche of extreme events with even higher intensities, culminating to a burst of a super rogue wave nearly ten times stronger than the average solitons observed in the cavity. Without any cavity modification or control, the process naturally and intermittently recurs within a time scale in the order of ten seconds.

Physical and functional connection between auxilin and dynamin during endocytosis

PubMed Central

Sever, Sanja; Skoch, Jesse; Newmyer, Sherri; Ramachandran, Rajesh; Ko, David; McKee, Mary; Bouley, Richard; Ausiello, Dennis; Hyman, Bradley T; Bacskai, Brian J

2006-01-01

During clathrin-mediated endocytosis, the GTPase dynamin promotes formation of clathrin-coated vesicles, but its mode of action is unresolved. We provide evidence that a switch in three functional states of dynamin (dimers, tetramers, rings/spirals) coordinates its GTPase cycle. Dimers exhibit negative cooperativity whereas tetramers exhibit positive cooperativity with respect to GTP. Our study identifies tetramers as the kinetically most stable GTP-bound conformation of dynamin, which is required to promote further assembly into higher order structures such as rings or spirals. In addition, using fluorescence lifetime imaging microscopy, we show that interactions between dynamin and auxilin in cells are GTP-, endocytosis- and tetramer-dependent. Furthermore, we show that the cochaperone activity of auxilin is required for constriction of clathrin-coated pits, the same early step in endocytosis known to be regulated by the lifetime of dynamin:GTP. Together, our findings support the model that the GTP-bound conformation of dynamin tetramers stimulates formation of constricted coated pits at the plasma membrane by regulating the chaperone activity of hsc70/auxilin. PMID:16946707

Response of a shell structure subject to distributed harmonic excitation

NASA Astrophysics Data System (ADS)

Cao, Rui; Bolton, J. Stuart

2016-09-01

Previously, a coupled, two-dimensional structural-acoustic ring model was constructed to simulate the dynamic and acoustical behavior of pneumatic tires. Analytical forced solutions were obtained and were experimentally verified through laser velocimeter measurement made using automobile tires. However, the two-dimensional ring model is incapable of representing higher order, in-plane modal motion in either the circumferential or axial directions. Therefore, in this paper, a three-dimensional pressurized circular shell model is proposed to study the in-plane shearing motion and the effect of different forcing conditions. Closed form analytical solutions were obtained for both free and forced vibrations of the shell under simply supported boundary conditions. Dispersion relations were calculated and different wave types were identified by their different speeds. Shell surface mobility results under various input distributions were also studied and compared. Spatial Fourier series decompositions were also performed on the spatial mobility results to give the forced dispersion relations, which illustrate clearly the influence of input force spatial distribution. Such a model has practical application in identifying the sources of noise and vibration problems in automotive tires.

Stable Isotope-Assisted Metabolic Profiling Reveals Growth Mode Dependent Differential Metabolism and Multiple Catabolic Pathways of l-Phenylalanine in Rubrivivax benzoatilyticus JA2.

PubMed

Mekala, Lakshmi Prasuna; Mohammed, Mujahid; Chintalapati, Sasikala; Chintalapati, Venkata Ramana

2018-01-05

Anoxygenic phototrophic bacteria are metabolically versatile and survive under different growth modes using diverse organic compounds, yet their metabolic diversity is largely unexplored. In the present study, we employed stable-isotope-assisted metabolic profiling to unravel the l-phenylalanine catabolism in Rubrivivax benzoatilyticus JA2 under varying growth modes. Strain JA2 grows under anaerobic and aerobic conditions by utilizing l-phenylalanine as a nitrogen source. Furthermore, ring-labeled 13 C 6 -phenylalanine feeding followed by liquid chromatography-mass spectrometry exometabolite profiling revealed 60 labeled metabolic features (M + 6, M + 12, and M + 18) derived solely from l-phenylalanine, of which 11 were identified, 7 putatively identified, and 42 unidentified under anaerobic and aerobic conditions. However, labeled metabolites were significantly higher in aerobic compared to anaerobic conditions. Furthermore, detected metabolites and enzyme activities indicated multiple l-phenylalanine catabolic routes mainly Ehrlich, homogentisate-dependent melanin, benzenoid, and unidentified pathways operating under anaerobic and aerobic conditions in strain JA2. Interestingly, the study indicated l-phenylalanine-dependent and independent benzenoid biosynthesis in strain JA2 and a differential flux of l-phenylalanine to Ehrlich and benzenoid pathways under anaerobic and aerobic conditions. Additionally, unidentified labeled metabolites strongly suggest the presence of unknown phenylalanine catabolic routes in strain JA2. Overall, the study uncovered the l-phenylalanine catabolic diversity in strain JA2 and demonstrated the potential of stable isotope-assisted metabolomics in unraveling the hidden metabolic repertoire.

Pooled versus separate tree-ring δD measurements, and implications for reconstruction of the Arctic Oscillation in northwestern China.

PubMed

Liu, Xiaohong; An, Wenling; Treydte, Kerstin; Wang, Wenzhi; Xu, Guobao; Zeng, Xiaomin; Wu, Guoju; Wang, Bo; Zhang, Xuanwen

2015-04-01

Stable hydrogen isotope ratios (δD) in tree rings are an attractive but still rarely explored terrestrial archive of past climatic information. Because the preparation of the cellulose nitrate for δD measurements requires more wood and a longer preparation time than preparation techniques for other isotopes in cellulose (δ18O or δ13C), it is challenging to obtain high-resolution records, especially for slow-growing trees at high elevations and in boreal regions. Here, we tested whether annually pooled samples of Qinghai spruce (Picea crassifolia Kom.) trees from northwestern China provided results similar to those derived as the mean of individual measurements of the same trees and whether the resulting chronologies recorded useful climate information. Inter-tree variability of δD was higher than that of measured ring width for the same trees. We found higher and significant coherence between pooled and mean isotope chronologies than that among the individual series. It showed a logarithmic relationship between ring mass and δD; however, accounting for the influence of ring mass on δD values only slightly improved the strength of climatic signals in the pooled records. Tree-ring δD was significantly positively correlated with the mean, maximum, and minimum temperatures during the previous winter and with maximum temperature during the current August, and significantly negatively correlated with precipitation in the previous November to January and the current July. The winter climate signal seems to dominate tree-ring δD through the influence of large-scale atmospheric circulation patterns, i.e. the Arctic Oscillation. These results will facilitate reconstruction of winter atmospheric circulation patterns over northwestern China based on a regional tree-ring δD networks. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of GIS-based models for delineating the UAV flight region to support Search and Rescue activities

NASA Astrophysics Data System (ADS)

Jurecka, Miroslawa; Niedzielski, Tomasz

2017-04-01

The objective of the approach presented in this paper is to demonstrate a potential of using the combination of two GIS-based models - mobility model and ring model - for delineating a region above which an Unmanned Aerial Vehicle (UAV) should fly to support the Search and Rescue (SAR) activities. The procedure is based on two concepts, both describing a possible distance/path that lost person could travel from the initial planning point (being either the point last seen, or point last known). The first approach (the ring model) takes into account the crow's flight distance traveled by a lost person and its probability distribution. The second concept (the mobility model) is based on the estimated travel speed and the associated features of the geographical environment of the search area. In contrast to the ring model covering global (hence more general) SAR perspective, the mobility model represents regional viewpoint by taking into consideration local impedance. Both models working together can serve well as a starting point for the UAV flight planning to strengthen the SAR procedures. We present the method of combining the two above-mentioned models in order to delineate UAVs flight region and increase the Probability of Success for future SAR missions. The procedure is a part of a larger Search and Rescue (SAR) system which is being developed at the University of Wrocław, Poland (research project no. IP2014 032773 financed by the Ministry of Science and Higher Education of Poland). The mobility and ring models have been applied to the Polish territory, and they act in concert to provide the UAV operator with the optimal search region. This is attained in real time so that the UAV-based SAR mission can be initiated quickly.

Properties of interstellar wind leading to shape morphology of the dust surrounding HD 61005

NASA Astrophysics Data System (ADS)

Pástor, P.

2017-08-01

Aims: A structure formed by dust particles ejected from the debris ring around HD 61005 is observed in the scattered light. The main aim here is to constrain interstellar wind parameters that lead to shape morphology in the vicinity of HD 61005 using currently available observational data for the debris ring. Methods: Equation of motion of 2 × 105 dust particles ejected from the debris ring under the action of the electromagnetic radiation, stellar wind, and interstellar wind is solved. A two-dimensional (2D) grid is placed in a given direction for accumulation of the light scattered on the dust particles in order to determine the shape morphology. The interaction of the interstellar wind and the stellar wind is considered. Results: Groups of unknown properties of the interstellar wind that create the observed morphology are determined. A relation between number densities of gas components in the interstellar wind and its relative velocity is found. Variations of the shape morphology caused by the interaction with the interstellar clouds of various temperatures are studied. When the interstellar wind velocity is tilted from debris ring axis a simple relation between the properties of the interstellar wind and an angle between the line of sight and the interstellar wind velocity exists. Dust particles that are most significantly influenced by stellar radiation move on the boundary of observed structure. Conclusions: Observed structure at HD 61005 can be explained as a result of dust particles moving under the action of the interstellar wind. Required number densities or velocities of the interstellar wind are much higher than that of the interstellar wind entering the solar system.

Application of the Collision-Imparted Velocity Method for Analyzing the Responses of Containment and Deflector Structures to Engine Rotor Fragment Impact

NASA Technical Reports Server (NTRS)

Collins, T. P.; Witmer, E. A.

1973-01-01

An approximate analysis, termed the Collision Imparted Velocity Method (CIVM), was employed for predicting the transient structural responses of containment rings or deflector rings which are subjected to impact from turbojet-engine rotor burst fragments. These 2-d structural rings may be initially circular or arbitrarily curved and may have either uniform or variable thickness; elastic, strain hardening, and strain rate material properties are accommodated. This approximate analysis utilizes kinetic energy and momentum conservation relations in order to predict the after-impact velocities of the fragment and the impacted ring segment. This information is then used in conjunction with a finite element structural response computation code to predict the transient, large deflection responses of the ring. Similarly, the equations of motion for each fragment are solved in small steps in time. Also, some comparisons of predictions with experimental data for fragment-impacted free containment rings are presented.

Chirally selective, intramolecular interaction observed in an aminoacyl adenylate anhydride

NASA Technical Reports Server (NTRS)

Lacey, J. C., Jr.; Hall, L. M.; Mullins, D. W., Jr.; Watkins, C. L.

1985-01-01

The interaction between amino acids and nucleotide bases is studied. The proton NMR spectrum of N-acetylphenylalanyl-AMP-anhydride is analyzed H8 and H2 signals, two upfield signals of equal size, and five phenylalanine ring proton signals are observed in the spectrum; the upfield movement of the proton and the racemization of the N-acetyl L-phenylalanine material are examined. The differences in the position of the signals due to the diastereoisomers are investigated. The separation of the D and L amino acyl adenylates using HPLC is described. H-1 NMR spectra of the isomers are examined in order to determine which isomer displays the strongest interaction between the phenyl ring and the adenine ring. The spectra reveal that the L isomer shows the highest upfield change of both H8 and H2 signals. It is noted that the phenyl ring lies over C2 of the adenine ring with the phenyl meta and para protons extended past the adenine ring and the phenyl ortho protons.

Toward improving the Laplacian estimation with novel multipolar concentric ring electrodes.

PubMed

Makeyev, Oleksandr; Ding, Quan; Kay, Steven M; Besio, Walter G

2013-01-01

Conventional electroencephalography with disc electrodes has major drawbacks including poor spatial resolution, selectivity and low signal-to-noise ratio that are critically limiting its use. Concentric ring electrodes are a promising alternative with potential to improve all of the aforementioned aspects significantly. In our previous work, the tripolar concentric ring electrode was successfully used in a wide range of applications demonstrating its superiority to conventional disc electrode, in particular, in accuracy of Laplacian estimation. This paper takes the first fundamental step toward further improving the Laplacian estimation of the novel multipolar concentric ring electrodes by proposing a general approach to estimation of the Laplacian for an (n + 1)-polar electrode with n rings using the (4n + 1)-point method for n ≥ 2 that allows cancellation of all the truncation terms up to the order of 2n. Examples of using the proposed approach to estimate the Laplacian for the cases of tripolar and, for the first time, quadripolar concentric ring electrode are presented.

B13+ : a photodriven molecular Wankel engine.

PubMed

Zhang, Jin; Sergeeva, Alina P; Sparta, Manuel; Alexandrova, Anastassia N

2012-08-20

Revved-up rotary: A molecular Wankel motor, the dual-ring structure B(13)(+), is driven by circularly-polarized infrared electromagnetic radiation. Calculations show that this illumination leads to a guided unidirectional rotation of the outer ring, which is achieved with rotational frequency of the order of 300 GHz. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Structure of Chariklo’s Rings from Stellar Occultations

NASA Astrophysics Data System (ADS)

Bérard, D.; Sicardy, B.; Camargo, J. I. B.; Desmars, J.; Braga-Ribas, F.; Ortiz, J.-L.; Duffard, R.; Morales, N.; Meza, E.; Leiva, R.; Benedetti-Rossi, G.; Vieira-Martins, R.; Gomes Júnior, A.-R.; Assafin, M.; Colas, F.; Dauvergne, J.-L.; Kervella, P.; Lecacheux, J.; Maquet, L.; Vachier, F.; Renner, S.; Monard, B.; Sickafoose, A. A.; Breytenbach, H.; Genade, A.; Beisker, W.; Bath, K.-L.; Bode, H.-J.; Backes, M.; Ivanov, V. D.; Jehin, E.; Gillon, M.; Manfroid, J.; Pollock, J.; Tancredi, G.; Roland, S.; Salvo, R.; Vanzi, L.; Herald, D.; Gault, D.; Kerr, S.; Pavlov, H.; Hill, K. M.; Bradshaw, J.; Barry, M. A.; Cool, A.; Lade, B.; Cole, A.; Broughton, J.; Newman, J.; Horvat, R.; Maybour, D.; Giles, D.; Davis, L.; Paton, R. A.; Loader, B.; Pennell, A.; Jaquiery, P.-D.; Brillant, S.; Selman, F.; Dumas, C.; Herrera, C.; Carraro, G.; Monaco, L.; Maury, A.; Peyrot, A.; Teng-Chuen-Yu, J.-P.; Richichi, A.; Irawati, P.; De Witt, C.; Schoenau, P.; Prager, R.; Colazo, C.; Melia, R.; Spagnotto, J.; Blain, A.; Alonso, S.; Román, A.; Santos-Sanz, P.; Rizos, J.-L.; Maestre, J.-L.; Dunham, D.

2017-10-01

Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned observations of several occultations by Chariklo’s system in order to better characterize the physical properties of the ring and main body. Here, we use 12 successful occulations by Chariklo observed between 2014 and 2016. They provide ring profiles (physical width, opacity, edge structure) and constraints on the radii and pole position. Our new observations are currently consistent with the circular ring solution and pole position, to within the ±3.3 km formal uncertainty for the ring radii derived by Braga-Ribas et al. The six resolved C1R profiles reveal significant width variations from ˜5 to 7.5 km. The width of the fainter ring C2R is less constrained, and may vary between 0.1 and 1 km. The inner and outer edges of C1R are consistent with infinitely sharp boundaries, with typical upper limits of one kilometer for the transition zone between the ring and empty space. No constraint on the sharpness of C2R’s edges is available. A 1σ upper limit of ˜20 m is derived for the equivalent width of narrow (physical width < 4 km) rings up to distances of 12,000 km, counted in the ring plane.

A node organization in the actomyosin contractile ring generates tension and aids stability.

PubMed

Thiyagarajan, Sathish; Wang, Shuyuan; O'Shaughnessy, Ben

2017-11-07

During cytokinesis, a contractile actomyosin ring constricts and divides the cell in two. How the ring marshals actomyosin forces to generate tension is not settled. Recently, a superresolution microscopy study of the fission yeast ring revealed that myosins and formins that nucleate actin filaments colocalize in plasma membrane-anchored complexes called nodes in the constricting ring. The nodes move bidirectionally around the ring. Here we construct and analyze a coarse-grained mathematical model of the fission yeast ring to explore essential consequences of the recently discovered ring ultrastructure. The model reproduces experimentally measured values of ring tension, explains why nodes move bidirectionally, and shows that tension is generated by myosin pulling on barbed-end-anchored actin filaments in a stochastic sliding-filament mechanism. This mechanism is not based on an ordered sarcomeric organization. We show that the ring is vulnerable to intrinsic contractile instabilities, and protection from these instabilities and organizational homeostasis require both component turnover and anchoring of components to the plasma membrane. © 2017 Thiyagarajan, Wang, and O’Shaughnessy. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Saturn's E Ring in Ultraviolet Light

NASA Technical Reports Server (NTRS)

2002-01-01

Visible from Earth only at times of ring plane crossing, Saturn's tenuous E Ring was discovered during the 1966 crossings and imaged again in 1980. From these observations, its color is known to be distinctively blue. The E Ring was captured in ultraviolet light for the first time in this image taken with HST's Wide Field and Planetary Camera on 9 August 1995. Five individual images taken with a broadband 3000 A filter were combined, amounting to a total exposure time of 2200 sec. Shorter exposure images were also obtained with blue, red and infrared filters in order to characterize the ring's color. The peak brightness of the E Ring occurs at 3.9 Saturn radii (235,000 km), coinciding with the orbit of Enceladus. In the HST images it can be traced out to a maximum distance of approximately 8 Rs (480,000 km). The vertical thickness of the ring, on the other hand, is smallest at Enceladus' orbit, with the ring puffing up noticeably at larger distances to 15,000 km or more thick. Also visible in this image, between the E Ring and the overexposed outermost part of the main rings near the lower edge of the frame, is the tenuous, thin, 6000 km-wide G Ring at 2.8 Rs (170,000 km). This is among the first earth-based observations of the G Ring, which was discovered by the Pioneer 11 spacecraft in 1979. Noticeably thinner than the E Ring and more neutral in color, the G Ring is thought to be composed of larger, macroscopic particles, and to pose a significant hazard to spacecraft. The faint diagonal band in the lower right part of the image is due to diffracted light from the heavily-overexposed planet. Credit: Phil Nicholson (Cornell University), Mark Showalter (NASA-Ames/Stanford) and NASA

Magnetic Property in Large Array Niobium Antidot Thin Films

NASA Astrophysics Data System (ADS)

Tinghui, Chen; Hsiang-Hsi, Kung; Wei-Li, Lee; Institute of Physics, Academia Sinica, Taipei, Taiwan Team

2014-03-01

In a superconducting ring, the total flux inside the ring is required to be an integer number of the flux quanta. Therefore, a supercurrent current can appear within the ring in order to satisfy this quantization rule, which gives rise to certain magnetic response. By using a special monolayer polymer/nanosphere hybrid we developed previously, we fabricated a series of superconducting niobium antidot thin films with different antidot diameters. The antidots form well-ordered triangular lattice with a lattice spacing about 200 nm and extend over an area larger than 1 cm2, which enables magnetic detections simply by a SQUID magnetometer. We observed magnetization oscillation with external magnetic field due to the supercurrent screening effect, where different features for large and small antidot thin films were found. Detailed size and temperature dependencies of the magnetization in niobium antidot nanostructures will be presented.

Manipulating electronic phase separation in strongly correlated oxides with an ordered array of antidots

DOE PAGES

Zhang, Kai; Du, Kai; Liu, Hao; ...

2015-07-20

The interesting transport and magnetic properties in manganites depend sensitively on the nucleation and growth of electronic phase-separated domains. In this paper, by fabricating antidot arrays in La 0.325Pr 0.3Ca 0.375MnO 3 (LPCMO) epitaxial thin films, we create ordered arrays of micrometer-sized ferromagnetic metallic (FMM) rings in the LPCMO films that lead to dramatically increased metal–insulator transition temperatures and reduced resistances. The FMM rings emerge from the edges of the antidots where the lattice symmetry is broken. Based on our Monte Carlo simulation, these FMM rings assist the nucleation and growth of FMM phase domains increasing the metal–insulator transition withmore » decreasing temperature or increasing magnetic field. Finally, this study points to a way in which electronic phase separation in manganites can be artificially controlled without changing chemical composition or applying external field.« less

An Instability in Narrow Planetary Rings

NASA Astrophysics Data System (ADS)

Weiss, J. W.; Stewart, G. R.

2003-08-01

We will present our work investigating the behavior of narrow planetary rings with low dispersion velocities. Such narrow a ring will be initially unstable to self-gravitational collapse. After the collapse, the ring is collisionally very dense. At this stage, it is subject to a new instability. Waves appear on the inner and outer edges of the ring within half of an orbital period. The ring then breaks apart radially, taking approximately a quarter of an orbital period of do so. As clumps of ring particles expand radially away from the dense ring, Kepler shear causes these clumps to stretch out azimuthally, and eventually collapse into a new set of dense rings. Small-scale repetitions of the original instability in these new rings eventually leads to a stabilized broad ring with higher dispersion velocities than the initial ring. Preliminary results indicate that this instability may be operating on small scales in broad rings in the wake-like features seen by Salo and others. Some intriguing properties have been observed during this instability. The most significant is a coherence in the epicyclic phases of the particles. Both self-gravity and collisions in the ring operated to create and enforce this coherence. The coherence might also be responsible for the instability to radial expansion. We also observe that guiding centers of the particles do not migrate to the center of the ring during the collapse phase of the ring. In fact, guiding centers move radially away from the core of the ring during this phase, consistent with global conservation of angular momentum. We will show the results of our simulations to date, including movies of the evolution of various parameters. (Audiences members wanting popcorn are advised to bring their own.) This work is supported by a NASA Graduate Student Research Program grant and by the Cassini mission.

Ionization of elements in medium power capacitively coupled argon plasma torch with single and double ring electrodes.

PubMed

Ponta, Michaela; Frentiu, Maria; Frentiu, Tiberiu

2012-06-01

A medium power, low Ar consumption capacitively coupled plasma torch (275 W, 0.4 L min-1) with molybdenum tubular electrode and single or two ring electrodes in non-local thermodynamic equilibrium (LTE) was characterized with respect to its ability to achieve element ionization. Ionization degrees of Ca, Mg, Mn and Cd were determined from ionic-to-atomic emission ratio and ionization equilibrium according to Saha's equation. The ionization degrees resulted from the Saha equation were higher by 9-32% than those obtained from spectral lines intensity in LTE regime and closer to reality. A linear decrease of ionization with increase of ionization energy of elements was observed. Plasma torch with two ring electrodes provided higher ionization degrees (85 ± 7% Ca, 79 ± 7% Mn, 80 ± 7% Mg and 73 ± 8% Cd) than those in single ring arrangement (70 ± 6% Ca, 57 ± 7% Mn, 57 ± 8% Mg and 42 ± 9% Cd). The Ca ionization decreased linearly by up to 79 ± 4% and 53 ± 6% in plasma with two ring electrodes and single ring respectively in the presence of up to 400 µg mL-1 Na as interferent. The studied plasma was effective in element ionization and could be a potential ion source in mass spectrometry.

Persistent organic pollutants in Alaskan ringed seal (Phoca hispida) and walrus (Odobenus rosmarus) blubber

USGS Publications Warehouse

Kucklick, John R.; Krahn, Margaret M.; Becker, Paul R.; Porter, Barbara J.; Schantz, Michele M.; York, Geoffrey S.; O'Hara, Todd M.; Wise, Stephen A.

2006-01-01

Since 1987, the Alaska Marine Mammal Tissue Archival Project (AMMTAP) has collected tissues from 18 marine mammal species. Specimens are archived in the National Institute of Standards and Technology's National Biomonitoring Specimen Bank (NIST-NBSB). AMMTAP has collected blubber, liver and/or kidney specimens from a number of ringed seals (Phoca hispida) from the areas near Nome and Barrow, Alaska and walruses (Odobenus rosmarus) from several locations in the Bering Sea. Thirty-three ringed seal and 15 walrus blubber samples from the NIST-NBSB were analyzed for persistent organic pollutants (POPs). The compounds determined included PCBs (28 congeners or congener groups), DDT and related compounds, hexachlorobenzene (HCB), hexachlorocyclohexane isomers (HCHs), chlordanes, dieldrin, and mirex. POP concentrations in ringed seal blubber were significantly higher in Barrow than in Nome when statistically accounting for the interaction of age and gender; HCB, however, was not statistically different between the two locations. Unlike males, POP concentrations and age were not significantly correlated in females probably as a result of lactational loss. POP concentrations in walrus blubber were lower than in ringed seal blubber for ΣPCBs, chlordanes, and HCHs, but higher for dieldrin and mirex. POP concentrations in ringed seals and walrus from Alaska provide further evidence that the western Arctic tends to have lower or similar POP concentrations compared to the eastern Canadian Arctic.

Variations in Ring Particle Cooling across Saturn's Rings with Cassini CIRS

NASA Astrophysics Data System (ADS)

Brooks, S. M.; Spilker, L. J.; Pilorz, S.; Edgington, S. G.; Déau, E.; Altobelli, N.

2010-12-01

Cassini's Composite Infrared Spectrometer has recorded over two million of spectra of Saturn's rings in the far infrared since arriving at Saturn in 2004. CIRS records far infrared radiation between 10 and 600 cm-1 ( 16.7 and 1000 μ {m} ) at focal plane 1 (FP1), which has a field of view of 3.9 mrad. Thermal emission from Saturn’s rings peaks in this wavelength range. Ring temperatures can be inferred from FP1 data. By tracking how ring temperatures vary, we can determine the thermal inertia of the rings. Previous studies have shown that the rings' thermal inertia, a measure of their response to changes in the thermal environment, varies from ring to ring. Thermal inertia can provide insight into the physical structure of Saturn's ring particles and their regoliths. Low thermal inertia and rapidly changing temperatures are suggestive of ring particles that have more porous or fluffy regoliths or that are riddled with cracks. Solid particles can be expected to have higher thermal inertias. Ferrari et al. (2005) fit thermal inertia values of 5218 {Jm)-2 {K}-1 {s}-1/2 to their B ring data and 6412 {Jm)-2 {K}-1 {s}-1/2 to their C ring data. In this work we focus on CIRS observations of the shadowed portion of Saturn's rings. The rings’ thermal budget is dominated by its absorption of solar radiation. As a result, ring particles abruptly cool as they traverse Saturn's shadow. From these shadow observations we can create cooling curves at specific locations across the rings. We will show that the rings' cooling curves and thus their thermal inertia vary not only from ring to ring, but by location within the individual rings. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. Copyright 2010 California Institute of Technology. Government sponsorship acknowledged.

Keeping the Edges Sharp I: Honing the Theory of Narrow Rings

NASA Astrophysics Data System (ADS)

Hamilton, Douglas P.; Rimlinger, Thomas; Hahn, Joseph M.

2016-05-01

Most of the rings that encircle Saturn, Uranus, and Neptune are very narrow structures with typical radial widths of just a few kilometers. Such extreme sharpness is surprising, as even slightly different orbital periods should allow ring particles to continually jostle one another in collisions that preserve angular momentum whileinexorably draining energy. Sharp edges should blur as rings spread in response to collisions and yet they do not. The generally accepted solution to this dilemma is to bracket each narrow ring with a pair of shepherding satellites that can pump energy back into the ring to replace that lost by collisions. But only a disappointing two of roughly twenty narrow rings actually have known attendant satellites. We present a compelling alternative in which the slight eccentricities and inclinations of narrow ringlets act as internal energy sources that can be tapped to prevent ring spreading. When unattended circular rings dissipate energy they must spread radially in order to preserve angular momentum. By contrast, eccentric or inclined rings have an extra degree of freedom that can be exploited to prevent radial spreading; energy is dissipated while keeping z-component of angular momentum, sqrt(a(1-e^2))cos(i), constant by simply decreasing the overall eccentricity (e) and/or inclination (i) of the entire ring. A real narrow ring moves inward as a unit, circularizes, and drops into the equatorial plane in a process that deters radial spreading for millions or billions of years. Using secular theory with dissipation (Zhang et al. 2013), we show that narrow rings are secular eigenstates in which ellipses are nested with pericenters almost, but not exactly aligned. The misalignment of pericenters is crucial in allowing energy dissipation to be shared evenly across the ring. We predict ring surface densities that are roughly constant across the ring's width, in contrast to profiles expected for shepherded rings. Rimlinger et al. (this meeting) present numerical simulations that critically test these findings.

Influencing factors on the size uniformity of self-assembled SiGe quantum rings grown by molecular beam epitaxy.

PubMed

Cui, J; Lv, Y; Yang, X J; Fan, Y L; Zhong, Z; Jiang, Z M

2011-03-25

The size uniformity of self-assembled SiGe quantum rings, which are formed by capping SiGe quantum dots with a thin Si layer, is found to be greatly influenced by the growth temperature and the areal density of SiGe quantum dots. Higher growth temperature benefits the size uniformity of quantum dots, but results in low Ge concentration as well as asymmetric Ge distribution in the dots, which induces the subsequently formed quantum rings to be asymmetric in shape or even broken somewhere in the ridge of rings. Low growth temperature degrades the size uniformity of quantum dots, and thus that of quantum rings. A high areal density results in the expansion and coalescence of neighboring quantum dots to form a chain, rather than quantum rings. Uniform quantum rings with a size dispersion of 4.6% and an areal density of 7.8×10(8) cm(-2) are obtained at the optimized growth temperature of 640°C.

Blue-detuned optical ring trap for Bose-Einstein condensates based on conical refraction.

PubMed

Turpin, A; Polo, J; Loiko, Yu V; Küber, J; Schmaltz, F; Kalkandjiev, T K; Ahufinger, V; Birkl, G; Mompart, J

2015-01-26

We present a novel approach for the optical manipulation of neutral atoms in annular light structures produced by the phenomenon of conical refraction occurring in biaxial optical crystals. For a beam focused to a plane behind the crystal, the focal plane exhibits two concentric bright rings enclosing a ring of null intensity called the Poggendorff ring. We demonstrate both theoretically and experimentally that the Poggendorff dark ring of conical refraction is confined in three dimensions by regions of higher intensity. We derive the positions of the confining intensity maxima and minima and discuss the application of the Poggendorff ring for trapping ultra-cold atoms using the repulsive dipole force of blue-detuned light. We give analytical expressions for the trapping frequencies and potential depths along both the radial and the axial directions. Finally, we present realistic numerical simulations of the dynamics of a ⁸⁷Rb Bose-Einstein condensate trapped inside the Poggendorff ring which are in good agreement with corresponding experimental results.

The KACST Heavy-Ion Electrostatic Storage Ring

NASA Astrophysics Data System (ADS)

Almuqhim, A. A.; Alshammari, S. M.; El Ghazaly, M. O. A.; Papash, A. I.; Welsch, C. P.

2011-10-01

A novel Electrostatic Storage Ring (ESR) for beams at energies up to 30keV/q is now being constructed at the National Centre for Mathematics and Physics (NCMP), King Abdul-Aziz City for Science and Technology (KACST). The ring is designed to be the core of a highly flexible experimental platform that will combine a large package of complementary beam techniques for atomic and molecular physics and related fields. The lattice design had to cover the different experimental techniques that the ring will be equipped with, such as e.g. Electron-Ion, Laser-Ion, Ion-Ion or Ion-Neutral beams, in both crossed and merged-beam configurations. The development of such an ESR is realized in a staged approach, in which a simple and early-run adaptation of the ring is built first, and then this basic version is upgraded to a higher symmetry of the ultimate version of the ring. Here, we report a general overview of this technical development with a focus on the layout of the first built stage of the ring.